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Skern-Mauritzen R, Malde K, Eichner C, Dondrup M, Furmanek T, Besnier F, Komisarczuk AZ, Nuhn M, Dalvin S, Edvardsen RB, Klages S, Huettel B, Stueber K, Grotmol S, Karlsbakk E, Kersey P, Leong JS, Glover KA, Reinhardt R, Lien S, Jonassen I, Koop BF, Nilsen F. The salmon louse genome: Copepod features and parasitic adaptations. Genomics 2021; 113:3666-3680. [PMID: 34403763 DOI: 10.1016/j.ygeno.2021.08.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/06/2021] [Accepted: 08/03/2021] [Indexed: 12/13/2022]
Abstract
Copepods encompass numerous ecological roles including parasites, detrivores and phytoplankton grazers. Nonetheless, copepod genome assemblies remain scarce. Lepeophtheirus salmonis is an economically and ecologically important ectoparasitic copepod found on salmonid fish. We present the 695.4 Mbp L. salmonis genome assembly containing ≈60% repetitive regions and 13,081 annotated protein-coding genes. The genome comprises 14 autosomes and a ZZ-ZW sex chromosome system. Assembly assessment identified 92.4% of the expected arthropod genes. Transcriptomics supported annotation and indicated a marked shift in gene expression after host attachment, including apparent downregulation of genes related to circadian rhythm coinciding with abandoning diurnal migration. The genome shows evolutionary signatures including loss of genes needed for peroxisome biogenesis, presence of numerous FNII domains, and an incomplete heme homeostasis pathway suggesting heme proteins to be obtained from the host. Despite repeated development of resistance against chemical treatments L. salmonis exhibits low numbers of many genes involved in detoxification.
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Affiliation(s)
| | - Ketil Malde
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway; Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Christiane Eichner
- Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Michael Dondrup
- Computational Biology Unit, Department of Informatics, University of Bergen, Thormøhlens Gate 55, 5008 Bergen, Norway
| | - Tomasz Furmanek
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway
| | - Francois Besnier
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway
| | - Anna Zofia Komisarczuk
- Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Michael Nuhn
- EMBL-The European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, CB10 1SD, UK
| | - Sussie Dalvin
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway
| | - Rolf B Edvardsen
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway
| | - Sven Klages
- Sequencing Core Facility, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Bruno Huettel
- Max Planck Genome Centre Cologne, Carl von Linné Weg 10, D-50829 Köln, Germany
| | - Kurt Stueber
- Max Planck Genome Centre Cologne, Carl von Linné Weg 10, D-50829 Köln, Germany
| | - Sindre Grotmol
- Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Egil Karlsbakk
- Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Paul Kersey
- EMBL-The European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, CB10 1SD, UK; Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AE, UK
| | - Jong S Leong
- Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada
| | - Kevin A Glover
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway; Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Richard Reinhardt
- Max Planck Genome Centre Cologne, Carl von Linné Weg 10, D-50829 Köln, Germany
| | - Sigbjørn Lien
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Oluf Thesens vei 6, 1433 Ås, Norway
| | - Inge Jonassen
- Computational Biology Unit, Department of Informatics, University of Bergen, Thormøhlens Gate 55, 5008 Bergen, Norway
| | - Ben F Koop
- Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada
| | - Frank Nilsen
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway; Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway.
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Coates A, Johnsen IA, Dempster T, Phillips BL. Parasite management in aquaculture exerts selection on salmon louse behaviour. Evol Appl 2021; 14:2025-2038. [PMID: 34429746 PMCID: PMC8372093 DOI: 10.1111/eva.13255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/18/2021] [Accepted: 05/12/2021] [Indexed: 11/28/2022] Open
Abstract
The evolution of pest resistance to management strategies is a major challenge for farmed systems. Mitigating the effects of pest adaptation requires identifying the selective pressures imposed by these strategies. In Atlantic salmon (Salmo salar) aquaculture, barriers are used to prevent salmon louse (Lepeophtheirus salmonis) larvae (copepodids) from entering salmon cages. These barriers are effective against shallow-swimming copepodids, but those swimming deeper can pass underneath and infest salmon. Laboratory experiments suggest that depth regulation in copepodids is a variable behavioural trait with a genetic basis. We used biological-hydrodynamic dispersal models to assess how this trait variation alters the dispersion of lice through the ocean environment and into farms. The dispersal of copepodids with 3 behavioural phenotypes (deep, mean or shallow) was modelled over winter-spring and spring-summer periods in a Norwegian fjord system with intensive aquaculture. The infestation pressure of each phenotype on barrier cages was estimated from their modelled depth distributions: copepodids deeper than 10 m were predicted to successfully pass underneath barriers. The deep phenotype was the most abundant below 10 m and reached infestation pressures 3 times higher than that of the mean phenotype. In contrast, the shallow phenotype infestation pressure reached less than half that of the mean phenotype. These differences in relative fitness indicate that barriers can impose strong directional selection on the swimming behaviour of copepodids. The strength of this selection varied seasonally and geographically, with selection for the deep phenotype stronger in winter-spring and at coastal locations than in spring-summer and within fjords. These findings can be applied across farms to slow louse adaptation, by limiting barriers during situations of strong selection, although this must be balanced against trade-offs to short-term efficacy. More broadly, our study highlights new ways in which dispersal models can address evolutionary questions crucial for sustainable parasite management in aquaculture.
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Affiliation(s)
- Andrew Coates
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT)School of BioSciencesUniversity of MelbourneParkvilleVic.Australia
- Spatial Ecology and Evolution Lab (SPEEL)School of BioSciencesUniversity of MelbourneParkvilleVic.Australia
| | | | - Tim Dempster
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT)School of BioSciencesUniversity of MelbourneParkvilleVic.Australia
| | - Ben L. Phillips
- Spatial Ecology and Evolution Lab (SPEEL)School of BioSciencesUniversity of MelbourneParkvilleVic.Australia
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Oral Immunization of Larvae and Juvenile of Lumpfish ( Cyclopterus lumpus) against Vibrio anguillarum Does Not Influence Systemic Immunity. Vaccines (Basel) 2021; 9:vaccines9080819. [PMID: 34451944 PMCID: PMC8402551 DOI: 10.3390/vaccines9080819] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 12/31/2022] Open
Abstract
Vibrio anguillarum, a marine bacterial pathogen that causes vibriosis, is a recurrent pathogen of lumpfish (Cyclopterus lumpus). Lumpfish is utilized as a cleaner fish in the Atlantic salmon (Salmo salar) aquaculture in the North Atlantic region because of its ability to visualize and prey on the ectoparasite sea lice (Lepeophtheirus salmonis) on the skin of Atlantic salmon, and its performance in cold environments. Lumpfish immunity is critical for optimal performance and sea lice removal. Oral vaccine delivery at a young age is the desired method for fish immunization because is easy to use, reduces fish stress during immunization, and can be applied on a large scale while the fish are at a young age. However, the efficacy of orally delivered inactivated vaccines is controversial. In this study, we evaluated the effectiveness of a V. anguillarum bacterin orally delivered to cultured lumpfish and contrasted it to an intraperitoneal (i.p.) boost delivery. We bio-encapsulated V. anguillarum bacterin in Artemia salina live-feed and orally immunized lumpfish larvae. Vaccine intake and immune response were evaluated by microscopy and quantitative polymerase chain reaction (qPCR) analysis, respectively. qPCR analyses showed that the oral immunization of lumpfish larvae resulted in a subtle stimulation of canonical immune transcripts such as il8b, il10, igha, ighmc, ighb, ccl19, ccl20, cd8a, cd74, ifng, and lgp2. Nine months after oral immunization, one group was orally boosted, and a second group was both orally and i.p. boosted. Two months after boost immunization, lumpfish were challenged with V. anguillarum (7.8 × 105 CFU dose−1). Orally boosted fish showed a relative percentage of survival (RPS) of 2%. In contrast, the oral and i.p. boosted group showed a RPS of 75.5% (p < 0.0001). V. anguillarum bacterin that had been orally delivered was not effective in lumpfish, which is in contrast to the i.p. delivered bacterin that protected the lumpfish against vibriosis. This suggests that orally administered V. anguillarum bacterin did not reach the deep lymphoid tissues, either in the larvae or juvenile fish, therefore oral immunization was not effective. Oral vaccines that are capable of crossing the epithelium and reach deep lymphoid tissues are required to confer an effective protection to lumpfish against V. anguillarum
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Oliveira VHS, Dean KR, Qviller L, Kirkeby C, Bang Jensen B. Factors associated with baseline mortality in Norwegian Atlantic salmon farming. Sci Rep 2021; 11:14702. [PMID: 34282173 PMCID: PMC8289829 DOI: 10.1038/s41598-021-93874-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 06/30/2021] [Indexed: 12/12/2022] Open
Abstract
In 2019, it was estimated that more than 50 million captive Atlantic salmon in Norway died in the final stage of their production in marine cages. This mortality represents a significant economic loss for producers and a need to improve welfare for farmed salmon. Single adverse events, such as algal blooms or infectious disease outbreaks, can explain mass mortality in salmon cages. However, little is known about the production, health, or environmental factors that contribute to their baseline mortality during the sea phase. Here we conducted a retrospective study including 1627 Atlantic salmon cohorts put to sea in 2014-2019. We found that sea lice treatments were associated with Atlantic salmon mortality. In particular, the trend towards non-medicinal sea lice treatments, including thermal delousing, increases Atlantic salmon mortality in the same month the treatment is applied. There were differences in mortality among production zones. Stocking month and weight were other important factors, with the lowest mortality in smaller salmon stocked in August-October. Sea surface temperature and salinity also influenced Atlantic salmon mortality. Knowledge of what affects baseline mortality in Norwegian aquaculture can be used as part of syndromic surveillance and to inform salmon producers on farming practices that can reduce mortality.
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Affiliation(s)
| | | | - Lars Qviller
- Norwegian Veterinary Institute, 1433, Ås, Norway
| | - Carsten Kirkeby
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870, Frederiksberg, Denmark
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55
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Sviland Walde C, Bang Jensen B, Pettersen JM, Stormoen M. Estimating cage-level mortality distributions following different delousing treatments of Atlantic salmon (salmo salar) in Norway. JOURNAL OF FISH DISEASES 2021; 44:899-912. [PMID: 33606885 DOI: 10.1111/jfd.13348] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/22/2021] [Accepted: 01/24/2021] [Indexed: 06/12/2023]
Abstract
This retrospective descriptive study estimates cage-level mortality distributions after six immediate delousing methods: thermal, mechanical, hydrogen peroxide, medicinal, freshwater and combination of medicinal treatments. We investigated mortality patterns associated with 4 644 delousing treatment of 1 837 cohorts of farmed Atlantic salmon (Salmo salar) stocked in sea along the Norwegian coast between 2014 and 2017. The mortality is expressed as mortality rates. We found distributions of delta mortality rate within 1, 7 and 14 days after all six delousing treatments, using mortality rate within 7 days before treatments as baseline. The results show that we can expect increased mortality rates after all six delousing methods. The median delta mortality rates after thermal and mechanical delousing are 5.4 and 6.3 times higher than medicinal treatment, respectively, for the 2017 year-class. There is a reduction in the delta median mortality for thermal and freshwater delousing from 2015 to 2019. There is a wide variability in the mortality rates, in particular for thermal delousing. Our results suggest that the variability in delta mortality for thermal delousing has been reduced from the 2014 to 2017 year-class, indicating an improvement of the technique. However, a significant increase in the number of thermal treatments from 14 in 2015 to 738 in 2018 probably contributes to the overall increased mortality in Norwegian salmon farming.
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Affiliation(s)
| | | | | | - Marit Stormoen
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
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Alvarado-Flores C, Encina-Montoya F, Tucca F, Vega-Aguayo R, Nimptsch J, Oberti C, Carmona ER, Lüders C. Assessing the ecological risk of active principles used currently by freshwater fish farms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 775:144716. [PMID: 33631559 DOI: 10.1016/j.scitotenv.2020.144716] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
The global aquaculture industry has grown exponentially in recent years using to control of infections and diseases, a variety of veterinary drugs (VMP) are used, including antibiotics, antifungals and antiparasitics, which have different routes of emission, environmental persistence and side effects to aquatic organisms, becoming one of the main concerns in its use of veterinary drugs (VMP) and its potential toxicological impact on the environment, in this context, Chile is considered one of the main salmon producers. Ecological risk assessment of active principles used infreshwater fish farms worldwide and in Chile were investigated. We recollect a physical - chemical properties of active principles used by fish farms and we could estimate the relative hazard a priori. Later active principles grouped as antibiotics (n = 6), antiparasitics (n = 5), anesthetics (n = 3), and disinfectants (n = 7) were assessed using a mass balance model based on fugacity was developed for each active principle under treatments via immersion and food administration in fish, while a volumetric model for disinfectants and sodium chloride was used for estimating the predicted environmental concentration (PEC), under a real smolt farming scenario in fish farms. Ecotoxicological data were collected from open literature to predict the no-effect concentration (PNEC). The ecological risk assessment was characterized using a risk quotient (RQ = PEC/PNEC) based in two assessment tiers. Results revealed that 12 active ingredients showed a high risk (RQ ≥ 1), thus indicating that adverse effects could occur and further investigation with measured concentrations in the field are required to reduce exposure in surface waters.
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Affiliation(s)
- Claudia Alvarado-Flores
- Department of Agricultural, Livestock and Aquiculture Sciences, Faculty of Natural Resources, Universidad Católica de Temuco, P.O. Box 15-D, Temuco, Chile; Doctoral Program of Agricultural and Livestock Sciences, Faculty of Natural Resources, Universidad Católica de Temuco, P.O. Box 15-D, Temuco, Chile
| | - Francisco Encina-Montoya
- Nucleus of Environmental Sciences (NEA), Universidad Católica de Temuco, Temuco, Chile; Department of Environmental Sciences, Faculty of Natural Resources, Universidad Católica de Temuco, Temuco, Chile.
| | - Felipe Tucca
- Norwegian Institute for Water Research (NIVA), Puerto Varas, Chile
| | - Rolando Vega-Aguayo
- Department of Agricultural, Livestock and Aquiculture Sciences, Faculty of Natural Resources, Universidad Católica de Temuco, P.O. Box 15-D, Temuco, Chile; Nucleus of Food Production (NIPA) Universidad Católica de Temuco, Temuco, Chile
| | - Jorge Nimptsch
- Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Edificio Emilio Pugin, Campus Isla Teja, Valdivia, Chile
| | - Carlos Oberti
- Department of Environmental Sciences, Faculty of Natural Resources, Universidad Católica de Temuco, Temuco, Chile
| | - Erico R Carmona
- Faculty of Natural Resources, Universidad Arturo Prat, Av. Arturo Prat s/n Campus Huayquique, Iquique, Chile
| | - Carlos Lüders
- Department of Veterinary Sciences, Faculty of Natural Resources, Universidad Católica de Temuco, P.O. Box 15-D, Temuco, Chile
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Zhou W, Krogdahl Å, Sæle Ø, Chikwati E, Løkka G, Kortner TM. Digestive and immune functions in the intestine of wild Ballan wrasse (Labrus bergylta). Comp Biochem Physiol A Mol Integr Physiol 2021; 260:111011. [PMID: 34174428 DOI: 10.1016/j.cbpa.2021.111011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/25/2022]
Abstract
This study was carried out to profile key characteristics of intestinal functions and health in wild-caught Ballan wrasse. To describe functional variation along the intestine, samples were collected from four intestinal segments, named from the proximal to the distal segment: IN1, IN2, IN3 and IN4. The sections showed quite similar structure, i.e. regarding mucosal fold height and branching, lamina propria and submucosal width and cellular composition and thickness of the muscle layers. Leucine aminopeptidase and maltase capacity decreased from IN1 to IN4, suggesting a predominant role of IN1 in digestion. Gene expression levels of vitamin C transporter (slc23a1) and fatty acid transporters (cd36 and fabp2) were higher in IN1 than in IN4, indicating a more important role of the proximal intestine regarding transport of vitamins and fatty acids. Higher expression of the gene coding for IgM heavy chain constant region (ighm) was found in IN4 than in IN1, suggesting an important immune function of the distal intestine. Other immune related genes il1b, il6, cd40, showed similar expression in the proximal and the distal part of the intestine. Parasite infection, especially the myxozoan parasite Enteromyxum leei, coincided with infiltration of lymphocytic and eosinophilic granular cells in the submucosa and lamina propria. The present study established reference information necessary for interpretation of results of studies of intestinal functions and health in cultured Ballan wrasse.
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Affiliation(s)
- Weiwen Zhou
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
| | - Åshild Krogdahl
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
| | - Øystein Sæle
- Feed and Nutrition, Institute of Marine Research, Bergen, Norway.
| | - Elvis Chikwati
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
| | - Guro Løkka
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
| | - Trond M Kortner
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
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Fjørtoft HB, Nilsen F, Besnier F, Stene A, Tveten AK, Bjørn PA, Aspehaug VT, Glover KA. Losing the 'arms race': multiresistant salmon lice are dispersed throughout the North Atlantic Ocean. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210265. [PMID: 34084551 PMCID: PMC8150044 DOI: 10.1098/rsos.210265] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
Nothing lasts forever, including the effect of chemicals aimed to control pests in food production. As old pesticides have been compromised by emerging resistance, new ones have been introduced and turned the odds back in our favour. With time, however, some pests have developed multi-pesticide resistance, challenging our ability to control them. In salmonid aquaculture, the ectoparasitic salmon louse has developed resistance to most of the available delousing compounds. The discovery of genetic markers associated with resistance to organophosphates and pyrethroids made it possible for us to investigate simultaneous resistance to both compounds in approximately 2000 samples of salmon lice from throughout the North Atlantic in the years 2000-2016. We observed widespread and increasing multiresistance on the European side of the Atlantic, particularly in areas with intensive aquaculture. Multiresistant lice were also found on wild Atlantic salmon and sea trout, and also on farmed salmonid hosts in areas where delousing chemicals have not been used. In areas with intensive aquaculture, there are almost no lice left that are sensitive to both compounds. These results demonstrate the speed to which this parasite can develop widespread multiresistance, illustrating why the aquaculture industry has repeatedly lost the arms race with this highly problematic parasite.
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Affiliation(s)
- Helene Børretzen Fjørtoft
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
| | - Frank Nilsen
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
| | | | - Anne Stene
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
| | - Ann-Kristin Tveten
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
| | - Pål Arne Bjørn
- Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway
| | | | - Kevin Alan Glover
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
- Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway
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Taylor RS, Slinger J, Stratford C, Rigby M, Wynne JW. Evaluation of the Infectious Potential of Neoparamoeba perurans Following Freshwater Bathing Treatments. Microorganisms 2021; 9:microorganisms9050967. [PMID: 33947171 PMCID: PMC8145359 DOI: 10.3390/microorganisms9050967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/24/2021] [Accepted: 04/27/2021] [Indexed: 11/16/2022] Open
Abstract
Freshwater bathing for 2–3 h is the main treatment to control amoebic gill disease of marine-farmed Atlantic salmon. Recent in vitro studies have demonstrated that amoebae (Neoparamoeba perurans) detach when exposed to freshwater and that some eventually reattach to culture plates when returned to seawater. Here, we evaluated the potential for gill-detached N. perurans to survive a commercially relevant treatment and infect AGD-naïve fish and whether holding used bathwater for up to 6 h post treatment would lower infectivity. AGD-affected fish were bathed in freshwater for 2 h. Naïve salmon were exposed to aliquots of the used bathwater after 2, 4, 6 and 8 h. The inoculation was performed at 30 ppt for 2 h, followed by gradual dilution with seawater. Sampling at 20 days post inoculation (dpi) and 40 dpi confirmed rapid AGD development in fish inoculated in 2 h used bathwater, but a slower AGD development following exposure to 4 h bathwater. AGD signs were variable and reduced following longer bathwater holding times. These results suggest that viable amoebae are likely returned to seawater following commercial freshwater treatments, but that the risk of infection can be reduced by retention of bathwater before release.
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Affiliation(s)
- Richard S. Taylor
- CSIRO Agriculture and Food, Castray Esplanade, Hobart, TAS 7000, Australia; (M.R.); (J.W.W.)
- Correspondence: ; Tel.: +61-3-62-325-089
| | - Joel Slinger
- CSIRO Agriculture and Food, Bribie Island Research Centre, Woorim, QLD 4507, Australia; (J.S.); (C.S.)
- Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7250, Australia
| | - Chris Stratford
- CSIRO Agriculture and Food, Bribie Island Research Centre, Woorim, QLD 4507, Australia; (J.S.); (C.S.)
| | - Megan Rigby
- CSIRO Agriculture and Food, Castray Esplanade, Hobart, TAS 7000, Australia; (M.R.); (J.W.W.)
| | - James W. Wynne
- CSIRO Agriculture and Food, Castray Esplanade, Hobart, TAS 7000, Australia; (M.R.); (J.W.W.)
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Umasuthan N, Valderrama K, Vasquez I, Segovia C, Hossain A, Cao T, Gnanagobal H, Monk J, Boyce D, Santander J. A Novel Marine Pathogen Isolated from Wild Cunners ( Tautogolabrus adspersus): Comparative Genomics and Transcriptome Profiling of Pseudomonas sp. Strain J380. Microorganisms 2021; 9:812. [PMID: 33921528 PMCID: PMC8069873 DOI: 10.3390/microorganisms9040812] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 04/08/2021] [Accepted: 04/09/2021] [Indexed: 12/13/2022] Open
Abstract
Cunner (Tautogolabrus adspersus) is a cleaner fish being considered for utilized in the North Atlantic salmon (Salmo salar) aquaculture industry to biocontrol sea lice infestations. However, bacterial diseases due to natural infections in wild cunners have yet to be described. This study reports the isolation of Pseudomonas sp. J380 from infected wild cunners and its phenotypic, genomic, and transcriptomic characterization. This Gram-negative motile rod-shaped bacterium showed a mesophilic (4-28 °C) and halotolerant growth. Under iron-limited conditions, Pseudomonas sp. J380 produced pyoverdine-type fluorescent siderophore. Koch's postulates were verified in wild cunners by intraperitoneally (i.p.) injecting Pseudomonas sp. J380 at 4 × 103, 4 × 105, and 4 × 107 colony forming units (CFU)/dose. Host-range and comparative virulence were also investigated in lumpfish and Atlantic salmon i.p. injected with ~106 CFU/dose. Lumpfish were more susceptible compared to cunners, and Atlantic salmon was resistant to Pseudomonas sp. J380 infection. Cunner tissues were heavily colonized by Pseudomonas sp. J380 compared to lumpfish and Atlantic salmon suggesting that it might be an opportunistic pathogen in cunners. The genome of Pseudomonas sp. J380 was 6.26 megabases (Mb) with a guanine-cytosine (GC) content of 59.7%. Biochemical profiles, as well as comparative and phylogenomic analyses, suggested that Pseudomonas sp. J380 belongs to the P. fluorescens species complex. Transcriptome profiling under iron-limited vs. iron-enriched conditions identified 1159 differentially expressed genes (DEGs). Cellular metabolic processes, such as ribosomal and energy production, and protein synthesis, were impeded by iron limitation. In contrast, genes involved in environmental adaptation mechanisms including two-component systems, histidine catabolism, and redox balance were transcriptionally up-regulated. Furthermore, iron limitation triggered the differential expression of genes encoding proteins associated with iron homeostasis. As the first report on a bacterial infection in cunners, the current study provides an overview of a new marine pathogen, Pseudomonas sp. J380.
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Affiliation(s)
- Navaneethaiyer Umasuthan
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (N.U.); (K.V.); (I.V.); (C.S.); (A.H.); (T.C.); (H.G.)
| | - Katherinne Valderrama
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (N.U.); (K.V.); (I.V.); (C.S.); (A.H.); (T.C.); (H.G.)
| | - Ignacio Vasquez
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (N.U.); (K.V.); (I.V.); (C.S.); (A.H.); (T.C.); (H.G.)
| | - Cristopher Segovia
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (N.U.); (K.V.); (I.V.); (C.S.); (A.H.); (T.C.); (H.G.)
| | - Ahmed Hossain
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (N.U.); (K.V.); (I.V.); (C.S.); (A.H.); (T.C.); (H.G.)
| | - Trung Cao
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (N.U.); (K.V.); (I.V.); (C.S.); (A.H.); (T.C.); (H.G.)
| | - Hajarooba Gnanagobal
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (N.U.); (K.V.); (I.V.); (C.S.); (A.H.); (T.C.); (H.G.)
| | - Jennifer Monk
- Dr. Joe Brown Aquatic Research Building (JBARB), Department of Ocean Sciences, Memorial University of Newfoundland, Logy Bay, NL A1C 5S7, Canada; (J.M.); (D.B.)
| | - Danny Boyce
- Dr. Joe Brown Aquatic Research Building (JBARB), Department of Ocean Sciences, Memorial University of Newfoundland, Logy Bay, NL A1C 5S7, Canada; (J.M.); (D.B.)
| | - Javier Santander
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (N.U.); (K.V.); (I.V.); (C.S.); (A.H.); (T.C.); (H.G.)
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Delfosse C, Pageat P, Lafont‐Lecuelle C, Asproni P, Chabaud C, Cozzi A, Bienboire‐Frosini C. Effect of handling and crowding on the susceptibility of Atlantic salmon (Salmo salar L.) to Lepeophtheirus salmonis (Krøyer) copepodids. JOURNAL OF FISH DISEASES 2021; 44:327-336. [PMID: 33112458 PMCID: PMC7894147 DOI: 10.1111/jfd.13286] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/26/2020] [Accepted: 09/29/2020] [Indexed: 05/08/2023]
Abstract
Lepeophtheirus salmonis is an ectoparasite causing economic concerns in Atlantic salmon farming. Salmon lice infestation management methods can be stressful and impact fish welfare. This work investigated the stress effect on the attachment of L. salmonis copepodids to Atlantic salmon through two approaches: (a) handling by netting and air exposure (acute stress), and (b) crowding with restricted surface access in a tank (chronic stress). In the first experiment, we compared the number of attached L. salmonis and cortisol levels between a group of handled salmon and a control group. In the second experiment, a group of densely packed salmon was compared to a control group based on the number of attached copepodids, cortisol levels and neutrophil:lymphocyte ratios. Handled salmon showed significantly higher plasma cortisol levels (p < .001) and more attached copepodids (p = .01) than control salmon. Conversely, the cortisol level and number of attached copepodids were not significantly different between the densely packed and control salmon (p > .05). The neutrophil:lymphocyte ratio was significantly higher (p = .0014) in the densely packed salmon than in the control salmon. Handling salmon increased their risk of infestation by L. salmonis. This has implications for reinfestation rates following delousing treatments in commercial salmon aquaculture, which often involve crowding and handling salmon.
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Affiliation(s)
- Cyril Delfosse
- Research Institute in Semiochemistry and Applied Ethology (IRSEA)AptFrance
- IRSEA‐ARCDaugstadNorway
| | - Patrick Pageat
- Research Institute in Semiochemistry and Applied Ethology (IRSEA)AptFrance
- IRSEA‐ARCDaugstadNorway
| | | | - Pietro Asproni
- Research Institute in Semiochemistry and Applied Ethology (IRSEA)AptFrance
| | - Camille Chabaud
- Research Institute in Semiochemistry and Applied Ethology (IRSEA)AptFrance
- IRSEA‐ARCDaugstadNorway
| | - Alessandro Cozzi
- Research Institute in Semiochemistry and Applied Ethology (IRSEA)AptFrance
- IRSEA‐ARCDaugstadNorway
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62
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St-Hilaire S, Cheng TH, Chan SCH, Leung CF, Chan KM, Lim KZ, Furtado W, Bastos Gomes G. Emamectin Benzoate Treatment of Hybrid Grouper Infected With Sea Lice in Hong Kong. Front Vet Sci 2021; 8:646652. [PMID: 33644159 PMCID: PMC7907643 DOI: 10.3389/fvets.2021.646652] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 01/21/2021] [Indexed: 11/16/2022] Open
Abstract
Sea lice (Copepoda: Caligidae) are ectoparasites which negatively impact marine aquaculture species around the world. There are a limited number of treatments licensed for use against sea lice in tropical and semi-tropical farmed fish species. Emamectin benzoate (EB) was an effective pharmaceutical drug against sea lice infestations in several salmon industries before resistance to the product developed. This drug has not been extensively tested in marine fish within Asia. The objective of this study was to determine whether this drug could be used to treat oral infections with sea lice in hybrid grouper (Mycteroperca tigris × Epinephelus lanceolatus) cultured in saltwater net-pen sites in Hong Kong. We observed an overall reduction in sea lice infections over time, starting on the last day of the treatment up to the end of our study (i.e., 14 days after the last EB treatment). We also observed a large variation in concentrations of EB in fish on the last day of the treatment, which provides an explanation for the variation in response to the treatment. It also suggests that distribution of the medication to fish in saltwater net-pens is difficult, especially when medication is hand-mixed in the feed and possibly unevenly distributed in the daily rations. Overall, this study provides preliminary evidence that EB could be used to treat sea lice found in Hong Kong and potentially in other regions of SE Asia.
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Affiliation(s)
- Sophie St-Hilaire
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong
| | - Tzu Hsuan Cheng
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong
| | - Stephen Chi Ho Chan
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong
| | - Chi Fai Leung
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong
| | - Ka Man Chan
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong
| | - Kwok Zu Lim
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong
| | - William Furtado
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong
| | - Giana Bastos Gomes
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, Singapore
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63
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Tschesche C, Bekaert M, Bassett DI, Mitchell C, North B, Boyd S, Carmona-Antoñanzas G, Bron JE, Sturm A. Investigation of deltamethrin resistance in salmon lice (Lepeophtheirus salmonis) provides no evidence for roles of mutations in voltage-gated sodium channels. PEST MANAGEMENT SCIENCE 2021; 77:1052-1060. [PMID: 33001569 DOI: 10.1002/ps.6120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/24/2020] [Accepted: 10/01/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The pyrethroid deltamethrin is used to treat infestations of farmed salmon by parasitic salmon lice, Lepeophtheirus salmonis (Krøyer). However, the efficacy of deltamethrin for salmon delousing is threatened by resistance development. In terrestrial arthropods, knockdown resistance (kdr) mutations of the voltage-gated sodium channel (Nav ), the molecular target for pyrethroids, can cause deltamethrin resistance. A putative kdr mutation of an L. salmonis sodium channel homologue (LsNav 1.3 I936V) has been identified previously. At the same time, deltamethrin resistance of L. salmonis has been shown to be inherited maternally and to be associated with mitochondrial DNA (mtDNA) mutations. This study assessed potential roles of the above putative kdr mutation as a determinant of deltamethrin resistance in laboratory strains and field populations of L. salmonis. RESULTS The deltamethrin-resistant L. salmonis strain IoA-02 expresses the LsNav 1.3 I936V mutation but was susceptible to the non-ester pyrethroid etofenprox, a compound against which pyrethroid-resistant arthropods are usually cross-resistant if resistance is caused by Nav mutations. In a family derived from a cross between an IoA-02 male and a drug-susceptible female lacking the kdr mutation, deltamethrin resistance was not associated with the genotype at the LsNav 1.3 locus (P > 0.05). Similarly, in Scottish field populations of L. salmonis, LsNav 1.3 I936V showed no association with deltamethrin resistance. By contrast, genotypes at the mtDNA loci A14013G and A9030G were significantly associated with deltamethrin resistance (P < 0.001). CONCLUSION In the studied L. salmonis isolates, deltamethrin resistance was unrelated to the LsNav 1.3 I936V mutation, but showed close association with mtDNA mutations.
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Affiliation(s)
- Claudia Tschesche
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - Michaël Bekaert
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - David I Bassett
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | | | | | - Sally Boyd
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - Greta Carmona-Antoñanzas
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
- Imegen, Parc Cientific de la Universitat de Valencia, Valencia, Spain
| | - James E Bron
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - Armin Sturm
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
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Harðardóttir HM, Male R, Nilsen F, Dalvin S. Chitin Synthases Are Critical for Reproduction, Molting, and Digestion in the Salmon Louse ( Lepeophtheirus salmonis). Life (Basel) 2021; 11:life11010047. [PMID: 33450932 PMCID: PMC7828418 DOI: 10.3390/life11010047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 11/30/2022] Open
Abstract
Chitin synthase (CHS) is a large transmembrane enzyme that polymerizes Uridine diphosphate N-acetylglucosamine into chitin. The genomes of insects often encode two chitin synthases, CHS1 and CHS2. Their functional roles have been investigated in several insects: CHS1 is mainly responsible for synthesizing chitin in the cuticle and CHS2 in the midgut. Lepeophtheirus salmonis is an ectoparasitic copepod on salmonid fish, which causes significant economic losses in aquaculture. In the present study, the tissue-specific localization, expression, and functional role of L. salmonis chitin synthases, LsCHS1 and LsCHS2, were investigated. The expressions of LsCHS1 and LsCHS2 were found in oocytes, ovaries, intestine, and integument. Wheat germ agglutinin (WGA) chitin staining signals were detected in ovaries, oocytes, intestine, cuticle, and intestine in adult female L. salmonis. The functional roles of the LsCHSs were investigated using RNA interference (RNAi) to silence the expression of LsCHS1 and LsCHS2. Knockdown of LsCHS1 in pre-adult I lice resulted in lethal phenotypes with cuticle deformation and deformation of ovaries and oocytes in adult lice. RNAi knockdown of LsCHS2 in adult female L. salmonis affected digestion, damaged the gut microvilli, reduced muscular tissues around the gut, and affected offspring. The results demonstrate that both LsCHS1 and LsCHS2 are important for the survival and reproduction in L. salmonis.
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Affiliation(s)
- Hulda María Harðardóttir
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, P.O. Box 7803, N-5020 Bergen, Norway; (R.M.); (F.N.)
- Correspondence:
| | - Rune Male
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, P.O. Box 7803, N-5020 Bergen, Norway; (R.M.); (F.N.)
| | - Frank Nilsen
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, P.O. Box 7803, N-5020 Bergen, Norway; (R.M.); (F.N.)
| | - Sussie Dalvin
- Sea Lice Research Centre, Institute of Marine Research, P.O. Box 1870, Nordnes, N-5817 Bergen, Norway;
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Herrmann B, Sistiaga M, Jørgensen T. Size-dependent escape risk of lumpfish (Cyclopterus lumpus) from salmonid farm nets. MARINE POLLUTION BULLETIN 2021; 162:111904. [PMID: 33321307 DOI: 10.1016/j.marpolbul.2020.111904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/25/2020] [Accepted: 11/29/2020] [Indexed: 06/12/2023]
Abstract
In the last decade, the salmon aquaculture industry has considerably increased the use of lumpfish juveniles as cleaner fish. Potential escape of reared lumpfish into the wild may spread diseases or genetically contaminate wild stocks. The guidelines for minimum sizes of cleaner fish to use in aquaculture cages are currently based on simple mesh penetration tests. However, these guidelines do not consider the potential compressibility of fish or changes in mesh state due to factors such as sea conditions and maintenance operations. This study shows that the industry-recommended minimum stocking sizes for a given mesh size may result in escape risk and that ignoring fish compressibility and mesh state can lead to underestimation of the lumpfish sizes that are able to escape. Our results can be used to develop new guidelines that will contribute to reduced escape of lumpfish from salmonid farms and lessen the potential environmental consequences.
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Affiliation(s)
- Bent Herrmann
- SINTEF Ocean, Brattørkaia 17C, N-7010 Trondheim, Norway; The Arctic University of Norway, UiT, Breivika, N-9037 Tromsø, Norway; DTU Aqua, Technical University of Denmark, Hirtshals, Denmark.
| | - Manu Sistiaga
- Institute of Marine Research, Postbox 1870, Nordnes, N-5817 Bergen, Norway; Norwegian University of Science and Technology, Otto Nielsens veg 10, N-7491 Trondheim, Norway
| | - Terje Jørgensen
- Institute of Marine Research, Postbox 1870, Nordnes, N-5817 Bergen, Norway
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Etayo A, Le HTMD, Araujo P, Lie KK, Sæle Ø. Dietary Lipid Modulation of Intestinal Serotonin in Ballan Wrasse ( Labrus bergylta)- In Vitro Analyses. Front Endocrinol (Lausanne) 2021; 12:560055. [PMID: 33833735 PMCID: PMC8021958 DOI: 10.3389/fendo.2021.560055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 03/01/2021] [Indexed: 12/28/2022] Open
Abstract
Serotonin (5-HT) is pivotal in the complex regulation of gut motility and consequent digestion of nutrients via multiple receptors. We investigated the serotonergic system in an agastric fish species, the ballan wrasse (Labrus bergylta) as it represents a unique model for intestinal function. Here we present evidence of the presence of enterochromaffin cells (EC cells) in the gut of ballan wrasse comprising transcriptomic data on EC markers like adra2a, trpa1, adgrg4, lmxa1, spack1, serpina10, as well as the localization of 5-HT and mRNA of the rate limiting enzyme; tryptophan hydroxylase (tph1) in the gut epithelium. Second, we examined the effects of dietary marine lipids on the enteric serotonergic system in this stomach-less teleost by administrating a hydrolyzed lipid bolus in ex vivo guts in an organ bath system. Modulation of the mRNA expression from the tryptophan hydroxylase tph1 (EC cells isoform), tph2 (neural isoform), and other genes involved in the serotonergic machinery were tracked. Our results showed no evidence to confirm that the dietary lipid meal did boost the production of 5-HT within the EC cells as mRNA tph1 was weakly regulated postprandially. However, dietary lipid seemed to upregulate the post-prandial expression of tph2 found in the serotonergic neurons. 5-HT in the intestinal tissue increased 3 hours after "exposure" of lipids, as was observed in the mRNA expression of tph2. This suggest that serotonergic neurons and not EC cells are responsible for the substantial increment of 5-HT after a lipid-reach "meal" in ballan wrasse. Cells expressing tph1 were identified in the gut epithelium, characteristic for EC cells. However, Tph1 positive cells were also present in the lamina propria. Characterization of these cells together with their implications in the serotonergic system will contribute to broad the scarce knowledge of the serotonergic system across teleosts.
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67
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Bateman AW, Peacock SJ, Krkošek M, Lewis MA. Migratory hosts can maintain the high-dose/refuge effect in a structured host-parasite system: The case of sea lice and salmon. Evol Appl 2020; 13:2521-2535. [PMID: 33294006 PMCID: PMC7691465 DOI: 10.1111/eva.12984] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 01/13/2023] Open
Abstract
Migration can reduce parasite burdens in migratory hosts, but it connects populations and can drive disease dynamics in domestic species. Farmed salmon are infested by sea louse parasites, often carried by migratory wild salmonids, resulting in a costly problem for industry and risk to wild populations when farms amplify louse numbers. Chemical treatment can control lice, but resistance has evolved in many salmon-farming regions. Resistance has, however, been slow to evolve in the north-east Pacific Ocean, where large wild-salmon populations harbour large sea louse populations. Using a mathematical model of host-macroparasite dynamics, we explored the roles of domestic, wild oceanic and connective migratory host populations in maintaining treatment susceptibility in associated sea lice. Our results show that a large wild salmon population, unexposed to direct infestation by lice from farms; high levels of on-farm treatment; and a healthy migratory host population are all critical to slowing or stopping the evolution of treatment resistance. Our results reproduce the "high-dose/refuge effect," from the agricultural literature, with the added requirement of a migratory host population to maintain treatment susceptibility. This work highlights the role that migratory hosts may play in shared wildlife/livestock disease, where evolution can occur in ecological time.
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Affiliation(s)
- Andrew W. Bateman
- Pacific Salmon FoundationVancouverBCCanada
- Salmon Coast Field StationSimoom SoundBCCanada
| | - Stephanie J. Peacock
- Salmon Coast Field StationSimoom SoundBCCanada
- Department of Biological SciencesUniversity of CalgaryCalgaryABCanada
| | - Martin Krkošek
- Salmon Coast Field StationSimoom SoundBCCanada
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Mark A. Lewis
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
- Department of Mathematical and Statistical SciencesUniversity of AlbertaEdmontonABCanada
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68
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Myhre Jensen E, Horsberg TE, Sevatdal S, Helgesen KO. Trends in de-lousing of Norwegian farmed salmon from 2000-2019-Consumption of medicines, salmon louse resistance and non-medicinal control methods. PLoS One 2020; 15:e0240894. [PMID: 33119627 PMCID: PMC7595418 DOI: 10.1371/journal.pone.0240894] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 10/01/2020] [Indexed: 12/02/2022] Open
Abstract
The salmon louse Lepeophtheirus salmonis has been a substantial obstacle in Norwegian farming of Atlantic salmon for decades. With a limited selection of available medicines and frequent delousing treatments, resistance has emerged among salmon lice. Surveillance of salmon louse sensitivity has been in place since 2013, and consumption of medicines has been recorded since the early 80’s. The peak year for salmon lice treatments was 2015, when 5.7 times as many tonnes of salmonids were treated compared to harvested. In recent years, non-medicinal methods of delousing farmed fish have been introduced to the industry. By utilizing data on the annual consumption of medicines, annual frequency of medicinal and non-medicinal treatments, the aim of the current study was to describe the causative factors behind salmon lice sensitivity in the years 2000–2019, measured through toxicity tests–bioassays. The sensitivity data from 2000–2012 demonstrate the early emergence of resistance in salmon lice along the Norwegian coast. Reduced sensitivity towards azamethiphos, deltamethrin and emamectin benzoate was evident from 2009, 2009 and 2007, respectively. The annual variation in medicine consumption and frequency of medicinal treatments correlated well with the evolution in salmon louse sensitivity. The patterns are similar, with a relatively small response delay from the decline in the consumption of medicines in Norway (2016 and onward) to the decline in measured resistance among salmon louse (2017 and onward). 2017 was the first year in which non-medicinal treatments outnumbered medicinal delousing treatments as well as the peak year in numbers of cleanerfish deployed. This study highlights the significance of avoiding heavy reliance on a few substance groups to combat ectoparasites, this can be a potent catalyst for resistance evolution. Further, it demonstrates the importance of transparency in the global industry, which enables the industry to learn from poor choices in the past.
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Affiliation(s)
- Elena Myhre Jensen
- Faculty of Veterinary Medicine, Sea Lice Research Center, Norwegian University of Life Sciences (NMBU), Oslo, Norway
- * E-mail:
| | - Tor Einar Horsberg
- Faculty of Veterinary Medicine, Sea Lice Research Center, Norwegian University of Life Sciences (NMBU), Oslo, Norway
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69
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Increasing temperatures accentuate negative fitness consequences of a marine parasite. Sci Rep 2020; 10:18467. [PMID: 33116171 PMCID: PMC7595087 DOI: 10.1038/s41598-020-74948-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 10/07/2020] [Indexed: 12/31/2022] Open
Abstract
Infectious diseases are key drivers of wildlife populations and agriculture production, but whether and how climate change will influence disease impacts remains controversial. One of the critical knowledge gaps that prevents resolution of this controversy is a lack of high-quality experimental data, especially in marine systems of significant ecological and economic consequence. Here, we performed a manipulative experiment in which we tested the temperature-dependent effects on Atlantic salmon (Salmo salar) of sea lice (Lepeophtheirus salmonis)—a parasite that can depress the productivity of wild-salmon populations and the profits of the salmon-farming industry. We explored sea-louse impacts on their hosts across a range of temperatures (10, 13, 16, 19, and 22 °C) and infestation levels (zero, ‘low’ (mean abundance ± SE = 1.6 ± 0.1 lice per fish), and ‘high’ infestation (6.8 ± 0.4 lice per fish)). We found that the effects of sea lice on the growth rate, condition, and survival of juvenile Atlantic salmon all worsen with increasing temperature. Our results provide a rare empirical example of how climate change may influence the impacts of marine disease in a key social-ecological system. These findings underscore the importance of considering climate-driven changes to disease impacts in wildlife conservation and agriculture.
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70
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Swain JK, Carpio Y, Johansen LH, Velazquez J, Hernandez L, Leal Y, Kumar A, Estrada MP. Impact of a candidate vaccine on the dynamics of salmon lice (Lepeophtheirus salmonis) infestation and immune response in Atlantic salmon (Salmo salar L.). PLoS One 2020; 15:e0239827. [PMID: 33006991 PMCID: PMC7531828 DOI: 10.1371/journal.pone.0239827] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 09/14/2020] [Indexed: 11/19/2022] Open
Abstract
Infection with parasitic copepod salmon louse Lepeophtheirus salmonis, represents one of the most important limitations to sustainable Atlantic salmon (Salmo salar L.) farming today in the North Atlantic region. The parasite exerts negative impact on health, growth and welfare of farmed fish as well as impact on wild salmonid populations. It is therefore central to ensure continuous low level of salmon lice with the least possible handling of the salmon and drug use. To address this, vaccination is a cost-effective and environmentally friendly control approach. In this study, efficacy of a vaccine candidate, containing a peptide derived from ribosomal protein P0, was validated post infestation with L. salmonis, at the lab-scale. The sampling results showed good potential of the vaccine candidate when administered intraperitoneally in the host, in reducing the ectoparasite load, through reduction of adult female lice counts and fecundity and with greater presumptive effect in F1 lice generation. The sampling results correlated well with the differential modulation of pro-inflammatory, Th1, Th2 and T regulatory mediators at the transcript level at different lice stages. Overall, the results supports approximately 56% efficacy when administered by intraperitoneal injection. However, additional validation is necessary under large-scale laboratory trial for further application under field conditions.
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Affiliation(s)
- Jaya Kumari Swain
- Nofima—The Food Research Institute, Tromsø, Norway
- * E-mail: (JKS); (YC); (MPE)
| | - Yamila Carpio
- Animal Biotechnology Division, Center for Genetic Engineering and Biotechnology, Havana, Cuba
- * E-mail: (JKS); (YC); (MPE)
| | | | - Janet Velazquez
- Animal Biotechnology Division, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Liz Hernandez
- Animal Biotechnology Division, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Yeny Leal
- Animal Biotechnology Division, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Ajey Kumar
- Symbiosis Centre for Information Technology, Symbiosis International (Deemed University), Pune, Maharashtra, India
| | - Mario Pablo Estrada
- Animal Biotechnology Division, Center for Genetic Engineering and Biotechnology, Havana, Cuba
- * E-mail: (JKS); (YC); (MPE)
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Dalvin S, Jørgensen LVG, Kania PW, Grotmol S, Buchmann K, Øvergård AC. Rainbow trout Oncorhynchus mykiss skin responses to salmon louse Lepeophtheirus salmonis: From copepodid to adult stage. FISH & SHELLFISH IMMUNOLOGY 2020; 103:200-210. [PMID: 32422189 DOI: 10.1016/j.fsi.2020.05.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 05/01/2020] [Accepted: 05/05/2020] [Indexed: 06/11/2023]
Abstract
The marine crustacean Lepeophtheirus salmonis (salmon louse) is a common ectoparasite of wild and farmed salmonids. The parasite has a complex ontogeny comprising eight instars. The planktonic copepodid stage settles on host skin and pass through five instars to reach the adult stage. The present study comprises an experimental infestation of Oncorhynchus mykiss (rainbow trout) with salmon lice and describes histopathology and host immune responses in skin beneath the louse at multiple time points encompassing all louse developmental stages. Each fish was exposed to 80 infective copepodids, a mean no. of 32 parasites reached the preadult I stage whereas a mean no. of 11 parasites reached the adult stage. A progression in the severity of cutaneous lesions was observed, and levels of immune gene transcripts at the attachment site revealed a dynamic response, initially related to innate immunity. Later, immune cells accumulated in the dermis concomitant with a moderate decrease in levels of transcripts characteristic of both innate and adaptive immune responses. The present study also demonstrates that the cutaneous immune response was mainly induced at lice affected sites, while non-affected skin resembled the skin of untreated control. This indicates that the skin cannot be regarded as a uniform organ and requires careful sampling at all salmon louse stages.
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Affiliation(s)
- Sussie Dalvin
- SLRC - Sea Lice Research Centre, Institute of Marine Research, 5817, Bergen, Norway; SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway
| | - Louise V G Jørgensen
- Laboratory of Aquatic Pathobiology, Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, 1870 Frb. C, Denmark
| | - Per W Kania
- Laboratory of Aquatic Pathobiology, Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, 1870 Frb. C, Denmark
| | - Sindre Grotmol
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway
| | - Kurt Buchmann
- Laboratory of Aquatic Pathobiology, Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, 1870 Frb. C, Denmark
| | - Aina-Cathrine Øvergård
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
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72
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Identification of critical enzymes in the salmon louse chitin synthesis pathway as revealed by RNA interference-mediated abrogation of infectivity. Int J Parasitol 2020; 50:873-889. [PMID: 32745476 DOI: 10.1016/j.ijpara.2020.06.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/10/2020] [Accepted: 06/18/2020] [Indexed: 12/12/2022]
Abstract
Treatment of infestation by the ectoparasite Lepeophtheirus salmonis relies on a small number of chemotherapeutant treatments that currently meet with limited success. Drugs targeting chitin synthesis have been largely successful against terrestrial parasites where the pathway is well characterised. However, a comparable approach against salmon lice has been, until recently, less successful, likely due to a poor understanding of the chitin synthesis pathway. Post-transcriptional silencing of genes by RNA interference (RNAi) is a powerful method for evaluation of protein function in non-model organisms and has been successfully applied to the salmon louse. In the present study, putative genes coding for enzymes involved in L. salmonis chitin synthesis were characterised after knockdown by RNAi. Nauplii I stage L. salmonis were exposed to double-stranded (ds) RNA specific for several putative non-redundant points in the pathway: glutamine: fructose-6-phosphate aminotransferase (LsGFAT), UDP-N-acetylglucosamine pyrophosphorylase (LsUAP), N-acetylglucosamine phosphate mutase (LsAGM), chitin synthase 1 (LsCHS1), and chitin synthase 2 (LsCHS2). Additionally, we targeted three putative chitin deacetylases (LsCDA4557, 5169 and 5956) by knockdown. Successful knockdown was determined after moulting to the copepodite stage by real-time quantitative PCR (RT-qPCR), while infectivity potential (the number of attached chalimus II compared with the initial number of larvae in the system) was measured after exposure to Atlantic salmon and subsequent development on their host. Compared with controls, infectivity potential was not compromised in dsAGM, dsCHS2, dsCDA4557, or dsCDA5169 groups. In contrast, there was a significant effect in the dsUAP-treated group. However, of most interest was the treatment with dsGFAT, dsCHS1, dsCHS1+2, and dsCDA5956, which resulted in complete abrogation of infectivity, despite apparent compensatory mechanisms in the chitin synthesis pathway as detected by qPCR. There appeared to be a common phenotypic effect in these groups, characterised by significant aberrations in appendage morphology and an inability to swim. Ultrastructurally, dsGFAT showed a significantly distorted procuticle without distinct exo/endocuticle and intermittent electron dense (i.e. chitin) inclusions, and together with dsUAP and dsCHS1, indicated delayed entry to the pre-moult phase.
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73
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Tackling the Molecular Drug Sensitivity in the Sea Louse Caligus rogercresseyi Based on mRNA and lncRNA Interactions. Genes (Basel) 2020; 11:genes11080857. [PMID: 32726954 PMCID: PMC7464394 DOI: 10.3390/genes11080857] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/21/2020] [Accepted: 07/24/2020] [Indexed: 01/05/2023] Open
Abstract
Caligus rogercresseyi, commonly known as sea louse, is an ectoparasite copepod that impacts the salmon aquaculture in Chile, causing losses of hundreds of million dollars per year. This pathogen is mainly controlled by immersion baths with delousing drugs, which can lead to resistant traits selection in lice populations. Bioassays are commonly used to assess louse drug sensitivity, but the current procedures may mask relevant molecular responses. This study aimed to discover novel coding genes and non-coding RNAs that could evidence drug sensitivity at the genomic level. Sea lice samples from populations with contrasting sensitivity to delousing drugs were collected. Bioassays using azamethiphos, cypermethrin, and deltamethrin drugs were conducted to evaluate the sensitivity and to collect samples for RNA-sequencing. Transcriptome sequencing was conducted on samples exposed to each drug to evaluate the presence of coding and non-coding RNAs associated with the response of these compounds. The results revealed specific transcriptome patterns in lice exposed to azamethiphos, deltamethrin, and cypermethrin drugs. Enrichment analyses of Gene Ontology terms showed specific biological processes and molecular functions associated with each delousing drug analyzed. Furthermore, novel long non-coding RNAs (lncRNAs) were identified in C. rogercresseyi and tightly linked to differentially expressed coding genes. A significant correlation between gene transcription patterns and phenotypic effects was found in lice collected from different salmon farms with contrasting drug treatment efficacies. The significant correlation among gene transcription patterns with the historical background of drug sensitivity suggests novel molecular mechanisms of pharmacological resistance in lice populations.
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74
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Coates A, Phillips BL, Oppedal F, Bui S, Overton K, Dempster T. Parasites under pressure: salmon lice have the capacity to adapt to depth-based preventions in aquaculture. Int J Parasitol 2020; 50:865-872. [PMID: 32652129 DOI: 10.1016/j.ijpara.2020.05.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/04/2020] [Accepted: 05/12/2020] [Indexed: 10/23/2022]
Abstract
The evolution of pesticide resistance has driven renewed interest in non-chemical pest controls in agriculture. Spatial manipulations (physical barriers and fallowing, for example) can be an effective method of prevention, but these too might impose selection and cause rapid adaptation in pests. In salmon aquaculture, various non-chemical approaches have emerged to combat parasitic salmon lice (Lepeophtheirus salmonis) - a major pest with clear signs of evolved chemical resistance. 'Depth-based' preventions, now widely implemented, reduce infestation rates by physically segregating salmon from lice in their infective copepodid stage occurring in surface waters. Copepodids distributed deeper in the water column, however, can bypass these barriers and infest farms. If swimming depth is a heritable trait, we may see rapid evolutionary shifts in response to widespread depth-based prevention. We collected lice from Norwegian salmon farms and assayed more than 11,250 of their laboratory-reared offspring across 37 families. The vertical distributions of copepodids were measured using experimental water columns pressurised to simulate conditions at 0, 5 and 10 m depths. We demonstrated that lice respond strongly to hydrostatic pressure: an increase in pressure doubled the number of lice that migrated to the top of columns. There was also a large effect of family on this response, with the percentage of lice ascending to the top of pressurised columns ranging from 17 to 79% across families. Families with a weak swimming response to pressure are expected to occur deeper in the water column and so be more likely to infest farms employing depth-based preventions. If this between-family variation reflects genetic variation, then the parasite population may have the capacity to adapt to preventative measures. Such adaptation would have important commercial and ecological implications.
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Affiliation(s)
- Andrew Coates
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia; Spatial Ecology and Evolution Lab (SpEEL), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Ben L Phillips
- Spatial Ecology and Evolution Lab (SpEEL), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Frode Oppedal
- Institute of Marine Research, Matre Aquaculture Research Station, 5984 Matredal, Norway
| | - Samantha Bui
- Institute of Marine Research, Matre Aquaculture Research Station, 5984 Matredal, Norway
| | - Kathy Overton
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia.
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75
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Candidate genes for monitoring hydrogen peroxide resistance in the salmon louse, Lepeophtheirus salmonis. Parasit Vectors 2020; 13:344. [PMID: 32650825 PMCID: PMC7350588 DOI: 10.1186/s13071-020-04211-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 07/02/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Hydrogen peroxide (H2O2) is one of the delousing agents used to control sea lice infestations in salmonid aquaculture. However, some Lepeophtheirus salmonis populations have developed resistance towards H2O2. An increased gene expression and activity of catalase, an enzyme that breaks down H2O2, have been detected in resistant lice, being therefore introduced as a resistance marker in the salmon industry. In the present study the aim was to validate the use of catalase expression as a marker and to identify new candidate genes as additional markers to catalase, related to H2O2 resistance in L. salmonis. METHODS A sensitive and an H2O2 resistant laboratory strain (P0 generation, not exposed to H2O2 for several years) were batch crossed to generate a cohort with a wide range of H2O2 sensitivities (F2 generation). F2 adult females were then exposed to H2O2 to separate sensitive and resistant individuals. Those F2 lice, the P0 lice and field-collected resistant lice (exposed to H2O2 in the field) were used in an RNA sequencing study. RESULTS Catalase was upregulated in resistant lice exposed to H2O2 compared to sensitive lice. This was, however, not the case for unexposed resistant P0 lice. Several other genes were found differentially expressed between sensitive and resistant lice, but most of them seemed to be related to H2O2 exposure. However, five genes were consistently up- or downregulated in the resistant lice independent of exposure history. The upregulated genes were: one gene in the DNA polymerase family, one gene encoding a Nesprin-like protein and an unannotated gene encoding a small protein. The downregulated genes encoded endoplasmic reticulum resident protein 29 and an aquaporin (Glp1_v2). CONCLUSIONS Catalase expression seems to be induced by H2O2 exposure, since it was not upregulated in unexposed resistant lice. This may pose a challenge for its use as a resistance marker. The five new genes associated with resistance are put forward as complementary candidate genes. The most promising was Glp1_v2, an aquaglyceroporin that may serve as a passing channel for H2O2. Lower channel number can reduce the influx or distribution of H2O2 in the salmon louse, being directly involved in the resistance mechanism.
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76
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Lennox RJ, Salvanes AGV, Barlaup BT, Stöger E, Madhun A, Helle TM, Vollset KW. Negative impacts of the sea lice prophylactic emamectin benzoate on the survival of hatchery released salmon smolts in rivers. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 224:105519. [PMID: 32502848 DOI: 10.1016/j.aquatox.2020.105519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/07/2020] [Accepted: 05/10/2020] [Indexed: 06/11/2023]
Abstract
Emamectin benzoate (EB) is a prophylactic pharmaceutical used to protect Atlantic salmon (Salmo salar) smolts migrating out of rivers and into the ocean against sea lice parasites. Randomized control trials comparing the marine survival of smolts treated with EB to a control group is used to calculate the fraction of marine mortality attributable to sea lice parasitism. However, it is assumed that there is no baseline difference in survival induced by the application of EB treatment. We used a combined laboratory and field study approach to investigate the potential impacts of EB treatment on behaviour and survival of hatchery-reared Atlantic salmon in western Norway. In aquaria experiments, EB-treated salmon smolts did not differ significantly in exploratory behaviour. Fish from treated groups responded similarly to simulated predator attack with spontaneous escape and elevated gill beat rate. Three rivers in the Osterfjord system of western Norway were selected for field experiments, Dale, Vosso, and Modalen. Dale River smolts were treated with intraperitoneal EB injections and had lower probability of detection in a wolf trap downstream of the release site than control smolts. Salmon smolts raised in the Vosso River hatchery were treated with EB delivered in their food and were detected on PIT antennas at the rivermouth of Vosso and Modalen at lower rates than control fish, but only when released at downstream sites. Calculation of risk ratios suggested that the bias in mortality caused by treatment with EB decreased the estimated survival of treated fish from an expected 18%to 46%, reducing the observable negative impact of sea lice on Atlantic salmon smolts in randomized control trials. The results suggest that estimates of the fraction of mortality attributable to sea lice may be underestimated due to lower baseline survival of treated fish caused by treatment and bring urgent attention towards a potential systematic underestimation of the impacts of sea lice on wild salmon.
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Affiliation(s)
- Robert J Lennox
- NORCE Norwegian Research Centre, Laboratory for Freshwater Ecology and Inland Fisheries (LFI), Nygårdsporten 112, 5008 Bergen, Norway.
| | | | - Bjørn T Barlaup
- NORCE Norwegian Research Centre, Laboratory for Freshwater Ecology and Inland Fisheries (LFI), Nygårdsporten 112, 5008 Bergen, Norway
| | - Elisabeth Stöger
- NORCE Norwegian Research Centre, Laboratory for Freshwater Ecology and Inland Fisheries (LFI), Nygårdsporten 112, 5008 Bergen, Norway
| | | | - Turid M Helle
- NORCE Norwegian Research Centre, Laboratory for Freshwater Ecology and Inland Fisheries (LFI), Nygårdsporten 112, 5008 Bergen, Norway
| | - Knut Wiik Vollset
- NORCE Norwegian Research Centre, Laboratory for Freshwater Ecology and Inland Fisheries (LFI), Nygårdsporten 112, 5008 Bergen, Norway
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77
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Braden LM, Monaghan SJ, Fast MD. Salmon immunological defence and interplay with the modulatory capabilities of its ectoparasite Lepeophtheirus salmonis. Parasite Immunol 2020; 42:e12731. [PMID: 32403169 DOI: 10.1111/pim.12731] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 03/13/2020] [Accepted: 05/06/2020] [Indexed: 12/16/2022]
Abstract
The salmon louse Lepeophtheirus salmonis (Lsal) is an ectoparasitic copepod that exerts immunomodulatory and physiological effects on its host Atlantic salmon. Over 30 years of research on louse biology, control, host responses and the host-parasite relationship has provided a plethora of information on the intricacies of host resistance and parasite adaptation. Atlantic salmon exhibit temporal and spatial impairment of the immune system and wound healing ability during infection. This immunosuppression may render Atlantic salmon less tolerant to stress and other confounders associated with current management strategies. Contrasting susceptibility of salmonid hosts exists, and early pro-inflammatory Th1 type responses are associated with resistance. Rapid cellular responses to larvae appear to tip the balance of the host-parasite relationship in favour of the host, preventing severe immune-physiological impacts of the more invasive adults. Immunological, transcriptomic, genomic and proteomic evidence suggests pathological impacts occur in susceptible hosts through modulation of host immunity and physiology via pharmacologically active molecules. Co-evolutionary and farming selection pressures may have incurred preference of Atlantic salmon as a host for Lsal reflected in their interactome. Here, we review host-parasite interactions at the primary attachment/feeding site, and the complex life stage-dependent molecular mechanisms employed to subvert host physiology and immune responses.
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Affiliation(s)
- Laura M Braden
- AquaBounty Canada, Bay Fortune, PEI, Canada.,Department of Pathology and Microbiology, Atlantic Veterinary College-UPEI, Charlottetown, PEI, Canada
| | - Sean J Monaghan
- Institute of Aquaculture, University of Stirling, Stirling, UK
| | - Mark D Fast
- Department of Pathology and Microbiology, Atlantic Veterinary College-UPEI, Charlottetown, PEI, Canada
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78
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Bui S, Geitung L, Oppedal F, Barrett LT. Salmon lice survive the straight shooter: A commercial scale sea cage trial of laser delousing. Prev Vet Med 2020; 181:105063. [PMID: 32593083 DOI: 10.1016/j.prevetmed.2020.105063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 06/10/2020] [Accepted: 06/10/2020] [Indexed: 10/24/2022]
Abstract
Ectoparasitic salmon louse (Lepeophtheirus salmonis) infestations are costly for Atlantic salmon (Salmo salar) farmers in Norway. As a result, there is a strong desire for solutions to prevent and control infestations, and new technologies are typically developed and commercialised rapidly, without rigorous validation. Here, we tested the efficacy of a new commercially available control measure-delousing by underwater lasers-using a replicated design at full commercial scale. Laser delousing was used in combination with a preventive method (snorkel cages), with laser nodes deployed in 3 of the 6 sea cages at the site. The trial ran for 54 days, after which time there was no difference in infestation density of mobile salmon louse stages (pre-adult, adult male or adult female) in cages with or without laser nodes installed. By the end of the trial, adult female lice numbers in all cages were close to the legislated trigger for mandatory delousing (0.5 adult female lice per fish). The laser nodes delivered a large number of pulses relative to the number of lice in the cages, indicating that a lack of lethality rather than a lack of target detection was the limiting factor. If all pulses had been effective, they should have removed between 4-38 % of mobile lice each day. There was no effect on salmon welfare indicators such as skin condition or eye status. Our results highlight the importance of rigorous validation of new technologies across a range of conditions before widespread implementation by industry.
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Affiliation(s)
- Samantha Bui
- Animal Welfare Research Group, Institute of Marine Research, Matredal 5984, Norway.
| | - Lena Geitung
- Bremnes Seashore AS, Øklandsvegen 90, 5430 Bremnes, Norway; Department of Biology, University of Bergen, 5006 Bergen, Norway
| | - Frode Oppedal
- Animal Welfare Research Group, Institute of Marine Research, Matredal 5984, Norway
| | - Luke T Barrett
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
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Heggland EI, Dondrup M, Nilsen F, Eichner C. Host gill attachment causes blood-feeding by the salmon louse (Lepeophtheirus salmonis) chalimus larvae and alters parasite development and transcriptome. Parasit Vectors 2020; 13:225. [PMID: 32375890 PMCID: PMC7201535 DOI: 10.1186/s13071-020-04096-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/24/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Blood-feeding is a common strategy among parasitizing arthropods, including the ectoparasitic salmon louse (Lepeophtheirus salmonis), feeding off its salmon host's skin and blood. Blood is rich in nutrients, among these iron and heme. These are essential molecules for the louse, yet their oxidative properties render them toxic to cells if not handled appropriately. Blood-feeding might therefore alter parasite gene expression. METHODS We infected Atlantic salmon with salmon louse copepodids and sampled the lice in two different experiments at day 10 and 18 post-infestation. Parasite development and presence of host blood in their intestines were determined. Lice of similar instar age sampled from body parts with differential access to blood, namely from gills versus lice from skin epidermis, were analysed for gene expression by RNA-sequencing in samples taken at day 10 for both experiments and at day 18 for one of the experiments. RESULTS We found that lice started feeding on blood when becoming mobile preadults if sitting on the fish body; however, they may initiate blood-feeding at the chalimus I stage if attached to gills. Lice attached to gills develop at a slower rate. By differential expression analysis, we found 355 transcripts elevated in lice sampled from gills and 202 transcripts elevated in lice sampled from skin consistent in all samplings. Genes annotated with "peptidase activity" were among the ones elevated in lice sampled from gills, while in the other group genes annotated with "phosphorylation" and "phosphatase" were pervasive. Transcripts elevated in lice sampled from gills were often genes relatively highly expressed in the louse intestine compared with other tissues, while this was not the case for transcripts elevated in lice sampled from skin. In both groups, more than half of the transcripts were from genes more highly expressed after attachment. CONCLUSIONS Gill settlement results in an alteration in gene expression and a premature onset of blood-feeding likely causes the parasite to develop at a slower pace.
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Affiliation(s)
- Erna Irene Heggland
- Department of Biological Sciences and Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Michael Dondrup
- Department of Informatics and Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Frank Nilsen
- Department of Biological Sciences and Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Christiane Eichner
- Department of Biological Sciences and Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway.
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Bechmann RK, Arnberg M, Bamber S, Lyng E, Westerlund S, Rundberget JT, Kringstad A, Seear PJ, Burridge L. Effects of exposing shrimp larvae (Pandalus borealis) to aquaculture pesticides at field relevant concentrations, with and without food limitation. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 222:105453. [PMID: 32112997 DOI: 10.1016/j.aquatox.2020.105453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/11/2020] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
Anti-parasitic drugs used in the aquaculture industry are discharged to the sea after treatment of salmon. In this study, the effects of azamethiphos (AZA) in the Salmosan® formulation and deltamethrin (DEL) in the Alpha Max® formulation, have been assessed in Northern shrimp larvae (Pandalus borealis) when administered both separately and in combination. The exposure concentrations were 100 ng/L for AZA and 2 ng/L for DEL, each representing a 1000-fold dilution of the prescribed concentrations for salmon. These two chemicals were combined at these concentrations to give a third treatment (AZA + DEL). When larvae were exposed for two hours on the first, second and third days post hatch (dph), significantly increased mortality and reduced swimming activity were observed for larvae from the DEL and combined AZA + DEL treatments 4 dph, though not in larvae from the AZA treatment. A single pulse exposure, delivered on the first day post hatch, caused similar effects on mortality and swimming activity 4 dph as the three-pulse exposure. Mortality was driven by the presence of DEL in both experiments, with no amplification or reduction of effects observed when DEL and AZA were combined. Larvae were observed for 13 days following the single pulse exposure, with food limitation introduced as an additional stressor on day 4. In the DEL and AZA + DEL treatments mortality continued to increase regardless of food level, with no larvae completing development to stage II. The overriding toxicity of DEL masked any potential effects the reduced food ration may have exerted. Swimming activity was lower for AZA treated larvae than Control larvae 13 dph, when both groups were fed daily, though no other significant changes to mortality, development to stage II, feeding rate or gene expression were observed. Food limited Control and AZA larvae had lower swimming activity and feeding rate than daily fed Control larvae, with expression of pyruvate kinase and myosin genes also downregulated. However, there was no negative effect on survival or successful development to stage II in these treatments. In addition, mesencephalic astrocyte-derived neurotropic factor was downregulated in food limited Control larvae when compared with the daily fed Controls. Results from this study together with reported estimates of dispersion plume concentrations of discharged pesticides indicate that toxic concentrations of deltamethrin could reach shrimp larvae several kilometers from a treated salmon farm.
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Affiliation(s)
| | - Maj Arnberg
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | - Shaw Bamber
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | - Emily Lyng
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | - Stig Westerlund
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | - Jan Thomas Rundberget
- The Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo, Norway.
| | - Alfhild Kringstad
- The Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo, Norway.
| | - Paul J Seear
- Department of Genetics and Genome Biology, Adrian Building, University Road, University of Leicester, LE1 7RH, Leicester, UK.
| | - Les Burridge
- Burridge Consulting Inc., 61 Emmalee Dr Stratford PE, Canada C1B 0B5, Canada.
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Bøhn T, Gjelland KØ, Serra‐Llinares RM, Finstad B, Primicerio R, Nilsen R, Karlsen Ø, Sandvik AD, Skilbrei OT, Elvik KMS, Skaala Ø, Bjørn PA. Timing is everything: Survival of Atlantic salmon
Salmo salar
postsmolts during events of high salmon lice densities. J Appl Ecol 2020. [DOI: 10.1111/1365-2664.13612] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | - Bengt Finstad
- Norwegian Institute for Nature Research (NINA) Trondheim Norway
- Department of Biology NTNU Center of Fisheries and Aquaculture Trondheim Norway
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Montory JA, Chaparro OR, Averbuj A, Salas-Yanquin LP, Büchner-Miranda JA, Gebauer P, Cumillaf JP, Cruces E. The filter-feeding bivalve Mytilus chilensis capture pelagic stages of Caligus rogercresseyi: A potential controller of the sea lice fish parasites. JOURNAL OF FISH DISEASES 2020; 43:475-484. [PMID: 32057114 DOI: 10.1111/jfd.13141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 06/10/2023]
Abstract
The copepod Caligus rogercresseyi is an ectoparasite of several salmonid species. The pumping activity of filter-feeding molluscs could reduce the abundance of copepod dispersive larval stages in the water column. In this research, nauplius II and copepodid larvae of C. rogercresseyi were exposed to filtering mussels (Mytilus chilensis) of different sizes. These mussels were able to filter both larval stages, although they were more efficient in catching nauplius II. The fact that nauplius II were ingested more efficiently could be explained by their smaller size, lower swimming velocity (escape) and longer resting times between movements, when they were exposed to the influx of water around the inhalant area of the mussels. Larger mussels were more effective filtering C. rogercresseyi larvae due to their larger inhalant area and the related water influx. Additionally, the results suggest that larvae captured by the mussels can be incorporated into pseudofaeces or ingested and then released as part of the faeces. Thus, high concentrations of M. chilensis surrounding salmon farms may act as biological barriers, reducing the density of copepod dispersive larval stages and, thus, salmon infestations.
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Affiliation(s)
| | - Oscar R Chaparro
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile
| | - Andres Averbuj
- Laboratorio de reproducción y biología integrativa de invertebrados marinos (LARBIM) - IBIOMAR, CCT CONICET - CENPAT, Puerto Madryn, Argentina
| | - Luis P Salas-Yanquin
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile
| | | | | | - Juan P Cumillaf
- Programa de Doctorado en Ciencias de la Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile
| | - Edgardo Cruces
- Centro de Investigaciones Costeras, Universidad de Atacama (CIC-UDA), Universidad de Atacama, Chile
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83
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Van AP, Álvarez de Haro N, Bron JE, Desbois AP. Chromatin extracellular trap release in rainbow trout, Oncorhynchus mykiss (Walbaum, 1792). FISH & SHELLFISH IMMUNOLOGY 2020; 99:227-238. [PMID: 31988016 DOI: 10.1016/j.fsi.2020.01.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/15/2020] [Accepted: 01/22/2020] [Indexed: 05/22/2023]
Abstract
Neutrophils release nuclear chromatin decorated with antimicrobial proteins into the extracellular milieu as an innate immune defence mechanism to counter invading microbes. These chromatin structures, called extracellular traps (ETs) and released by a process called NETosis, have been detected in mammals, certain invertebrates and some fish species, including fathead minnow, zebrafish, common carp, turbot, sole and barramundi. However, there have been no previous studies of ETs in the Salmonidae. ETs are released in response to chemical and biological stimuli, but observations from different fish species are inconsistent, particularly regarding the potency of various inducers and inhibitors. Thus, this present study aimed to describe ET release in a salmonid (rainbow trout, Oncorhynchus mykiss (Walbaum, 1792)) and uncover the inducers and inhibitors that can control this response. Highly enriched suspensions of polymorphonuclear cells (PMNs; mainly neutrophils) were prepared from head kidney tissues by a triple-layer Percoll gradient technique. ET structures were visualised in PMN-enriched suspensions through staining of the chromatin with nucleic acid-specific dyes and immunocytochemical probing of characteristic proteins expected to decorate the structure. ET release was quantified after incubation with inducers and inhibitors known to affect this response in other organisms. Structures resembling ETs stained positively with SYTOX Green (a stain specific for nucleic acid) while immunocytochemistry was used to detect neutrophil elastase, myeloperoxidase and H2A histone in the structures, which are diagnostic proteinaceous markers of ETs. Consistent with other studies on mammals and some fish species, calcium ionophore and flagellin were potent inducers of ETs, while cytochalasin D inhibited NETosis. Phorbol 12-myristate 13-acetate (PMA), used commonly to induce ETs, exerted only weak stimulatory activity, while heat-killed bacteria and lipopolysaccharide did not induce ET release. Unexpectedly, the ET-inhibitor diphenyleneiodonium chloride acted as an inducer of ET release, an observation not reported elsewhere. Taken together, these data confirm for the first time that ETs are released by salmonid PMNs and compounds useful for manipulating NETosis were identified, thus providing a platform for further studies to explore the role of this mechanism in fish immunity. This new knowledge provides a foundation for translation to farm settings, since manipulation of the innate immune response offers a potential alternative to the use of antibiotics to mitigate against microbial infections, particularly for pathogens where protection by vaccination has yet to be realised.
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Affiliation(s)
- Andre P Van
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom
| | - Neila Álvarez de Haro
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom
| | - James E Bron
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom
| | - Andrew P Desbois
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom.
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84
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Umasuthan N, Xue X, Caballero-Solares A, Kumar S, Westcott JD, Chen Z, Fast MD, Skugor S, Nowak BF, Taylor RG, Rise ML. Transcriptomic Profiling in Fins of Atlantic Salmon Parasitized with Sea Lice: Evidence for an Early Imbalance Between Chalimus-Induced Immunomodulation and the Host's Defense Response. Int J Mol Sci 2020; 21:E2417. [PMID: 32244468 PMCID: PMC7177938 DOI: 10.3390/ijms21072417] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/27/2020] [Indexed: 01/08/2023] Open
Abstract
Parasitic sea lice (e.g., Lepeophtheirus salmonis) cause costly outbreaks in salmon farming. Molecular insights into parasite-induced host responses will provide the basis for improved management strategies. We investigated the early transcriptomic responses in pelvic fins of Atlantic salmon parasitized with chalimus I stage sea lice. Fin samples collected from non-infected (i.e. pre-infected) control (PRE) and at chalimus-attachment sites (ATT) and adjacent to chalimus-attachment sites (ADJ) from infected fish were used in profiling global gene expression using 44 K microarrays. We identified 6568 differentially expressed probes (DEPs, FDR < 5%) that included 1928 shared DEPs between ATT and ADJ compared to PRE. The ATT versus ADJ comparison revealed 90 DEPs, all of which were upregulated in ATT samples. Gene ontology/pathway term network analyses revealed profound changes in physiological processes, including extracellular matrix (ECM) degradation, tissue repair/remodeling and wound healing, immunity and defense, chemotaxis and signaling, antiviral response, and redox homeostasis in infected fins. The QPCR analysis of 37 microarray-identified transcripts representing these functional themes served to confirm the microarray results with a significant positive correlation (p < 0.0001). Most immune/defense-relevant transcripts were downregulated in both ATT and ADJ sites compared to PRE, suggesting that chalimus exerts immunosuppressive effects in the salmon's fins. The comparison between ATT and ADJ sites demonstrated the upregulation of a suite of immune-relevant transcripts, evidencing the salmon's attempt to mount an anti-lice response. We hypothesize that an imbalance between immunomodulation caused by chalimus during the early phase of infection and weak defense response manifested by Atlantic salmon makes it a susceptible host for L. salmonis.
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Affiliation(s)
- Navaneethaiyer Umasuthan
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (X.X.); (A.C.-S.); (S.K.)
| | - Xi Xue
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (X.X.); (A.C.-S.); (S.K.)
| | - Albert Caballero-Solares
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (X.X.); (A.C.-S.); (S.K.)
| | - Surendra Kumar
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (X.X.); (A.C.-S.); (S.K.)
| | - Jillian D. Westcott
- Fisheries and Marine Institute, Memorial University of Newfoundland, P.O. Box 4920, St. John’s, NL A1C 5R3, Canada; (J.D.W.); (Z.C.)
| | - Zhiyu Chen
- Fisheries and Marine Institute, Memorial University of Newfoundland, P.O. Box 4920, St. John’s, NL A1C 5R3, Canada; (J.D.W.); (Z.C.)
| | - Mark D. Fast
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada;
| | - Stanko Skugor
- Cargill Aqua Nutrition, Cargill, Sea Lice Research Center (SLRC), Hanaveien 17, 4327 Sandnes, Norway;
| | - Barbara F. Nowak
- Institute of Marine and Antarctic Studies, University of Tasmania, Locked Bag 1370, Launceston 7250, TAS, Australia;
| | - Richard G. Taylor
- Cargill Animal Nutrition, 10383 165th Avenue NW, Elk River, MN 55330, USA;
| | - Matthew L. Rise
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (X.X.); (A.C.-S.); (S.K.)
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85
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Barrett LT, Pert CG, Bui S, Oppedal F, Dempster T. Sterilization of sea lice eggs with ultraviolet C light: towards a new preventative technique for aquaculture. PEST MANAGEMENT SCIENCE 2020; 76:901-906. [PMID: 31441192 DOI: 10.1002/ps.5595] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/19/2019] [Accepted: 08/20/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Sea lice infestations on Atlantic salmon (Salmo salar) farms are a considerable burden on the industry and put wild salmonid populations at risk. Frequent delousing treatments are necessary to keep lice densities below allowable limits, but currently viable treatments have drawbacks in terms of financial cost, animal welfare, or environmental impacts. We tested if 254 nm ultraviolet C light (UVC) could function as a new preventative method to suppress reproduction of salmon lice (Lepeophtheirus salmonis) by sterilizing fertilized eggs. We exposed salmon lice eggstrings to a range of UVC intensities and durations to identify effective doses. RESULTS A cumulative dose of 0.008 J cm-2 induced 5% egg mortality, while 95% egg mortality occurred at 0.09 J cm-2 , indicating that UVC can be effective as a preventative treatment. The total cumulative dose appeared to be more important than the duration or number of individual exposures by which the total dose was achieved. CONCLUSION UVC treatment has immediate applications for the salmon aquaculture industry, including for the treatment of wastewater from delousing or other operations. Future work will assess the feasibility of UVC dose delivery on host salmon in sea cage environments that involves little or no fish handling and creates negligible environmental impacts. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Luke T Barrett
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria, Australia
| | - Cassandra G Pert
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria, Australia
| | - Samantha Bui
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Frode Oppedal
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria, Australia
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86
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Flores-Kossack C, Montero R, Köllner B, Maisey K. Chilean aquaculture and the new challenges: Pathogens, immune response, vaccination and fish diversification. FISH & SHELLFISH IMMUNOLOGY 2020; 98:52-67. [PMID: 31899356 DOI: 10.1016/j.fsi.2019.12.093] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 11/29/2019] [Accepted: 12/30/2019] [Indexed: 06/10/2023]
Abstract
In Chile, the salmon and trout farmed fishing industries have rapidly grown during the last years, becoming one of the most important economic sources for the country. However, infectious diseases caused by bacteria, virus, mycoses and parasites, result in losses of up to 700 million dollars per year for the Chilean aquaculture production with the consequent increase of antibiotic and antiparasitic usage. After 30 years of its first appearance, the main salmon health problem is still the salmonid rickettsial septicaemia (SRS), which together with other disease outbreaks, reveal that vaccines do not provide acceptable levels of long-lasting immune protection in the field. On the other hand, due to the large dependence of the industry on salmonids production, the Chilean government promoted the Aquaculture diversification program by 2009, which includes new species such as Merluccius australis, Cilus gilberti and Genypterus chilensis, however, specific research regarding the immune system and vaccine development are issues that still need to be addressed and must be considered as important as the farm production technologies for new fish species. Based on the experience acquired from the salmonid fish farming, should be mandatory an effort to study the immune system of the new species to develop knowledge for vaccination approaches, aiming to protect these aquaculture species before diseases outbreaks may occur. This review focuses on the current status of the Chilean aquaculture industry, the challenges related to emerging and re-emerging microbial pathogens on salmonid fish farming, and the resulting needs in the development of immune protection by rational designed vaccines. We also discussed about what we have learn from 25 years of salmonid researches and what can be applied to the new Chilean farmed species on immunology and vaccinology.
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Affiliation(s)
- C Flores-Kossack
- Laboratorio de Inmunología Comparativa, Centro de Biotecnología Acuícola (CBA), Universidad de Santiago de Chile, Alameda, 3363, Santiago, Chile
| | - R Montero
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - B Köllner
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - K Maisey
- Laboratorio de Inmunología Comparativa, Centro de Biotecnología Acuícola (CBA), Universidad de Santiago de Chile, Alameda, 3363, Santiago, Chile.
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87
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Gonçalves AT, Collipal-Matamal R, Valenzuela-Muñoz V, Nuñez-Acuña G, Valenzuela-Miranda D, Gallardo-Escárate C. Nanopore sequencing of microbial communities reveals the potential role of sea lice as a reservoir for fish pathogens. Sci Rep 2020; 10:2895. [PMID: 32076035 PMCID: PMC7031262 DOI: 10.1038/s41598-020-59747-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 02/03/2020] [Indexed: 12/11/2022] Open
Abstract
Caligus rogercresseyi is a copepod ectoparasite with a high prevalence in salmon farms in Chile, causing severe welfare and economic concerns to the sector. Information on the parasite's underpinning mechanisms to support its life strategy is recently being investigated. Due to the critical role of microbiota, this study aimed to characterize the microbiota community associated with C. rogercresseyi from different regions with salmon aquaculture in Chile. Using third-generation sequencing with Nanopore technology (MinION) the full 16S rRNA gene from sea lice obtained from 8 areas distributed over the three main aquaculture regions were sequenced. Microbiota of the parasite is mainly comprised of members of phyla Proteobacteria and Bacteroidetes, and a core microbiota community with 147 taxonomical features was identified, and it was present in sea lice from the three regions. This community accounted for 19% of total identified taxa but more than 70% of the total taxonomical abundance, indicating a strong presence in the parasite. Several taxa with bioactive compound secretory capacity were identified, such as members of genus Pseudoalteromonas and Dokdonia, suggesting a possible role of the lice microbiota during the host infestation processes. Furthermore, the microbiota community was differentially associated with the salmon production, where several potential pathogens such as Vibrio, Tenacibaculum, and Aeromonas in Los Lagos, Aysén, and Magallanes region were identified. Notably, the Chilean salmon industry was initially established in the Los Lagos region but it's currently moving to the south, where different oceanographic conditions coexist with lice populations. The results originated by this study will serve as foundation to investigate putative role of sea lice as vectors for fish pathogens and also as reservoirs for antibiotic-resistant genes.
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Affiliation(s)
- Ana Teresa Gonçalves
- Interdisciplinary Center for Aquaculture Research, University of Concepción, Concepción, Chile.,Laboratory of Biotechnology and Aquatic Genomics, Center of Biotechnology, University of Concepción, Concepción, Chile
| | - Rayen Collipal-Matamal
- Laboratory of Biotechnology and Aquatic Genomics, Center of Biotechnology, University of Concepción, Concepción, Chile
| | - Valentina Valenzuela-Muñoz
- Interdisciplinary Center for Aquaculture Research, University of Concepción, Concepción, Chile.,Laboratory of Biotechnology and Aquatic Genomics, Center of Biotechnology, University of Concepción, Concepción, Chile
| | - Gustavo Nuñez-Acuña
- Interdisciplinary Center for Aquaculture Research, University of Concepción, Concepción, Chile.,Laboratory of Biotechnology and Aquatic Genomics, Center of Biotechnology, University of Concepción, Concepción, Chile
| | - Diego Valenzuela-Miranda
- Interdisciplinary Center for Aquaculture Research, University of Concepción, Concepción, Chile.,Laboratory of Biotechnology and Aquatic Genomics, Center of Biotechnology, University of Concepción, Concepción, Chile
| | - Cristian Gallardo-Escárate
- Interdisciplinary Center for Aquaculture Research, University of Concepción, Concepción, Chile. .,Laboratory of Biotechnology and Aquatic Genomics, Center of Biotechnology, University of Concepción, Concepción, Chile.
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88
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Barrett LT, Overton K, Stien LH, Oppedal F, Dempster T. Effect of cleaner fish on sea lice in Norwegian salmon aquaculture: a national scale data analysis. Int J Parasitol 2020; 50:787-796. [PMID: 32035989 DOI: 10.1016/j.ijpara.2019.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/25/2019] [Accepted: 12/03/2019] [Indexed: 11/24/2022]
Abstract
The salmon aquaculture industry has adopted the use of invertivorous 'cleaner fishes' (CF) for biological control of sea louse infestations on farmed salmon. At present, ~50 million CF are used annually in Norway alone, with variable success in experimental and industrial contexts. We used a national scale database of louse counts, delousing treatments and CF stocking events on Norwegian salmon farms to test for evidence of CF efficacy at 488 sites that completed a grow-out cycle within 2016-2018. Our analysis revealed that sites using more CF over the duration of a grow-out cycle did not have fewer lice on average, likely because CF use is reactive and in proportion to the scale of the louse problem. Over time within sites, we found that (i) sites using more CF early in the grow-out cycle were able to wait slightly longer (conservatively, a 5.2 week delay with 5000 CF stocked week-1) before conducting the first delousing treatment, and (ii) CF stocking events were followed, on average, by a small reduction in louse population growth rates. However, both effects were small and highly variable, and louse population growth rates remained positive on average, even when large numbers of CF were used (tens of thousands per site). Moreover, effects of CF on louse density tended to be short-lived, likely reflecting mortality and escape of stocked CF. Overall, the data indicate that while some sites consistently obtain good results from CF, there is also widespread suboptimal use. A better understanding of factors affecting CF efficacy in commercial sea cages is required to inform legislation and drive more efficient and ethical use of CF by the salmon aquaculture industry.
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Affiliation(s)
- Luke T Barrett
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia.
| | - Kathy Overton
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Lars H Stien
- Institute of Marine Research, Matre Research Station, 5984 Matredal, Norway
| | - Frode Oppedal
- Institute of Marine Research, Matre Research Station, 5984 Matredal, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
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89
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Sea lice exposure to non-lethal levels of emamectin benzoate after treatments: a potential risk factor for drug resistance. Sci Rep 2020; 10:932. [PMID: 31969584 PMCID: PMC6976678 DOI: 10.1038/s41598-020-57594-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 01/03/2020] [Indexed: 11/24/2022] Open
Abstract
The avermectin derivative emamectin benzoate (EMB) has been widely used by salmon industries around the world to control sea lice infestations. Resistance to this anti-parasitic drug is also commonly reported in these industries. The objective of this study was to quantify the number of sea lice potentially exposed to sub-lethal concentrations of EMB while fish clear the drug after treatments. We assessed juvenile sea lice abundance after 38 EMB treatments on six Atlantic salmon farms, in a small archipelago in British Colombia, Canada, between 2007 and 2018. We fitted a standard EMB pharmacokinetic curve to determine the time when fish treated with this product would have EMB tissue concentrations below the recommended target therapeutic level. During the study, we estimated that for each sea lice treatment there was, on average, an abundance of 0.12 juvenile sea lice per fish during the time period when the concentrations of EMB would have been lower than 60ppb, the recommended therapeutic treatment level for sea lice. The findings from this study on metaphylactic anti-parasitic treatments identify a potential driver for drug resistance in sea lice that should be further explored.
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90
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Contreras M, Karlsen M, Villar M, Olsen RH, Leknes LM, Furevik A, Yttredal KL, Tartor H, Grove S, Alberdi P, Brudeseth B, de la Fuente J. Vaccination with Ectoparasite Proteins Involved in Midgut Function and Blood Digestion Reduces Salmon Louse Infestations. Vaccines (Basel) 2020; 8:vaccines8010032. [PMID: 31963779 PMCID: PMC7157638 DOI: 10.3390/vaccines8010032] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/16/2020] [Accepted: 01/17/2020] [Indexed: 11/16/2022] Open
Abstract
Infestation with the salmon louse Lepeophtheirus salmonis (Copepoda, Caligidae) affects Atlantic salmon (Salmo salar L.) production in European aquaculture. Furthermore, high levels of salmon lice in farms significantly increase challenge pressure against wild salmon populations. Currently, available control methods for salmon louse have limitations, and vaccination appears as an attractive, environmentally sound strategy. In this study, we addressed one of the main limitations for vaccine development, the identification of candidate protective antigens. Based on recent advances in tick vaccine research, herein, we targeted the salmon louse midgut function and blood digestion for the identification of candidate target proteins for the control of ectoparasite infestations. The results of this translational approach resulted in the identification and subsequent evaluation of the new candidate protective antigens, putative Toll-like receptor 6 (P30), and potassium chloride, and amino acid transporter (P33). Vaccination with these antigens provided protection in Atlantic salmon by reducing adult female (P33) or chalimus II (P30) sea lice infestations. These results support the development of vaccines for the control of sea lice infestations.
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Affiliation(s)
- Marinela Contreras
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain; (M.C.); (M.V.); (P.A.)
| | - Marius Karlsen
- Pharmaq AS, P.O. Box 267, Skoyen, N-0213 Oslo, Norway; (M.K.); (R.H.O.); (L.M.L.); (A.F.); (K.L.Y.)
| | - Margarita Villar
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain; (M.C.); (M.V.); (P.A.)
- Biochemistry Section, Faculty of Science and Chemical Technologies, and Regional Centre for Biomedical Research (CRIB), University of Castilla-La Mancha, 13071 Ciudad Real, Spain
| | - Rolf Hetlelid Olsen
- Pharmaq AS, P.O. Box 267, Skoyen, N-0213 Oslo, Norway; (M.K.); (R.H.O.); (L.M.L.); (A.F.); (K.L.Y.)
| | - Lisa Marie Leknes
- Pharmaq AS, P.O. Box 267, Skoyen, N-0213 Oslo, Norway; (M.K.); (R.H.O.); (L.M.L.); (A.F.); (K.L.Y.)
| | - Anette Furevik
- Pharmaq AS, P.O. Box 267, Skoyen, N-0213 Oslo, Norway; (M.K.); (R.H.O.); (L.M.L.); (A.F.); (K.L.Y.)
| | - Karine Lindmo Yttredal
- Pharmaq AS, P.O. Box 267, Skoyen, N-0213 Oslo, Norway; (M.K.); (R.H.O.); (L.M.L.); (A.F.); (K.L.Y.)
| | - Haitham Tartor
- Norwegian Veterinary Institute, 0106 Oslo, Norway; (H.T.); (S.G.)
| | - Soren Grove
- Norwegian Veterinary Institute, 0106 Oslo, Norway; (H.T.); (S.G.)
- Institute of Marine Research, 5005 Bergen, Norway
| | - Pilar Alberdi
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain; (M.C.); (M.V.); (P.A.)
| | - Bjorn Brudeseth
- Pharmaq AS, P.O. Box 267, Skoyen, N-0213 Oslo, Norway; (M.K.); (R.H.O.); (L.M.L.); (A.F.); (K.L.Y.)
- Correspondence: (B.B.); (J.d.l.F.)
| | - José de la Fuente
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain; (M.C.); (M.V.); (P.A.)
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
- Correspondence: (B.B.); (J.d.l.F.)
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91
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Harrington PD, Lewis MA. A Next-Generation Approach to Calculate Source-Sink Dynamics in Marine Metapopulations. Bull Math Biol 2020; 82:9. [PMID: 31932972 DOI: 10.1007/s11538-019-00674-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 12/02/2019] [Indexed: 11/26/2022]
Abstract
In marine systems, adult populations confined to isolated habitat patches can be connected by larval dispersal. Source-sink theory provides effective tools to quantify the effect of specific habitat patches on the dynamics of connected populations. In this paper, we construct the next-generation matrix for a marine metapopulation and demonstrate how it can be used to calculate the source-sink dynamics of habitat patches. We investigate the effect of environmental variables on the source-sink dynamics and demonstrate how the next-generation matrix can provide useful biological insight into transient as well as asymptotic dynamics of the model.
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Affiliation(s)
- Peter D Harrington
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada.
| | - Mark A Lewis
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada
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92
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Major KM, Brander SM. The Ecological and Evolutionary Implications of Pyrethroid Exposure: A New Perspective on Aquatic Ecotoxicity. THE HANDBOOK OF ENVIRONMENTAL CHEMISTRY 2020. [DOI: 10.1007/698_2019_432] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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93
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Humble JL, Carmona-Antoñanzas G, McNair CM, Nelson DR, Bassett DI, Egholm I, Bron JE, Bekaert M, Sturm A. Genome-wide survey of cytochrome P450 genes in the salmon louse Lepeophtheirus salmonis (Krøyer, 1837). Parasit Vectors 2019; 12:563. [PMID: 31775848 PMCID: PMC6880348 DOI: 10.1186/s13071-019-3808-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 11/15/2019] [Indexed: 11/24/2022] Open
Abstract
Background The salmon louse (Lepeophtheirus salmonis) infests farmed and wild salmonid fishes, causing considerable economic damage to the salmon farming industry. Infestations of farmed salmon are controlled using a combination of non-medicinal approaches and veterinary drug treatments. While L. salmonis has developed resistance to most available salmon delousing agents, relatively little is known about the molecular mechanisms involved. Members of the cytochrome P450 (CYP) superfamily are typically monooxygenases, some of which are involved in the biosynthesis and metabolism of endogenous compounds, while others have central roles in the detoxification of xenobiotics. In terrestrial arthropods, insecticide resistance can be based on the enhanced expression of CYPs. The reported research aimed to characterise the CYP superfamily in L. salmonis and assess its potential roles in drug resistance. Methods Lepeophtheirus salmonis CYPs were identified by homology searches of the genome and transcriptome of the parasite. CYP transcript abundance in drug susceptible and multi-resistant L. salmonis was assessed by quantitative reverse transcription PCR, taking into account both constitutive expression and expression in parasites exposed to sublethal levels of salmon delousing agents, ecdysteroids and environmental chemicals. Results The above strategy led to the identification of 25 CYP genes/pseudogenes in L. salmonis, making its CYP superfamily the most compact characterised for any arthropod to date. Lepeophtheirus salmonis possesses homologues of a number of arthropod CYP genes with roles in ecdysteroid metabolism, such as the fruit fly genes disembodied, shadow, shade, spook and Cyp18a1. CYP transcript expression did not differ between one drug susceptible and one multi-resistant strain of L. salmonis. Exposure of L. salmonis to emamectin benzoate or deltamethrin caused the transcriptional upregulation of certain CYPs. In contrast, neither ecdysteroid nor benzo[a]pyrene exposure affected CYP transcription significantly. Conclusions The parasite L. salmonis is demonstrated to possess the most compact CYP superfamily characterised for any arthropod to date. The complement of CYP genes in L. salmonis includes conserved CYP genes involved in ecdysteroid biosynthesis and metabolism, as well as drug-inducible CYP genes. The present study does not provide evidence for a role of CYP genes in the decreased susceptibility of the multiresistant parasite strain studied. ![]()
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Affiliation(s)
- Joseph L Humble
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | | | - Carol M McNair
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - David R Nelson
- Department of Microbiology, University of Tennessee, Memphis, TN, 38163, USA
| | - David I Bassett
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Ingibjørg Egholm
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - James E Bron
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Michaël Bekaert
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Armin Sturm
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
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94
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Pietrak M, Rosser TG. Morphologic and molecular characterization of Gyrodactylus cyclopteri Scyborskaja, 1948, from Cyclopterus lumpus L., 1758. Parasitol Res 2019; 119:879-884. [PMID: 31768683 DOI: 10.1007/s00436-019-06542-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 11/06/2019] [Indexed: 11/25/2022]
Abstract
Interest and use of the lumpfish Cyclopterus lumpus L., 1758, as a cleaner fish in salmon aquaculture has grown significantly over the past 10 years. This has resulted in an explosion of new hatcheries to supply juveniles to the salmon industry. Until recently, these hatcheries have utilized a significant amount of wild broodstock to source the eggs required. Importation of wild fish into aquaculture systems brings an inherent risk of introducing pathogens into the culture systems. Gyrodactylus cyclopteri Scyborskaja, 1948, was found on local wild collected lumpfish that were brought in to start a captive lumpfish aquaculture program in Maine. Little information on the identification or description of G. cyclopteri was available. A re-description of the parasite, supplemented with molecular data, was undertaken to facilitate future identification and support research on this parasite of an emerging, economically significant new aquaculture species.
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Affiliation(s)
- Michael Pietrak
- Agricultural Research Service, National Cold Water Marine Aquaculture Center, United States Department of Agriculture, Franklin, ME, 04634, USA.
| | - Thomas Graham Rosser
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, 39762, USA
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95
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Thompson CRS, Fields DM, Bjelland RM, Chan VBS, Durif CMF, Mount A, Runge JA, Shema SD, Skiftesvik AB, Browman HI. The planktonic stages of the salmon louse ( Lepeophtheirus salmonis) are tolerant of end-of-century pCO 2 concentrations. PeerJ 2019; 7:e7810. [PMID: 31632848 PMCID: PMC6796963 DOI: 10.7717/peerj.7810] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/01/2019] [Indexed: 01/13/2023] Open
Abstract
The copepod Lepeophtheirus salmonis is an obligate ectoparasite of salmonids. Salmon lice are major pests in salmon aquaculture and due to its economic impact Lepeophtheirus salmonis is one of the most well studied species of marine parasite. However, there is limited understanding of how increased concentration of pCO2 associated with ocean acidification will impact host-parasite relationships. We investigated the effects of increased pCO2 on growth and metabolic rates in the planktonic stages, rearing L. salmonis from eggs to 12 days post hatch copepodids under three treatment levels: Control (416 µatm), Mid (747 µatm), and High (942 µatm). The pCO2 treatment had a significant effect on oxygen consumption rate with the High treatment animals exhibiting the greatest respiration. The treatments did not have a significant effect on the other biological endpoints measured (carbon, nitrogen, lipid volume, and fatty acid content). The results indicate that L. salmonis have mechanisms to compensate for increased concentration of pCO2and that populations will be tolerant of projected future ocean acidification scenarios. The work reported here also describes catabolism during the lecithotrophic development of L. salmonis, information that is not currently available to parameterize models of dispersal and viability of the planktonic free-living stages.
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Affiliation(s)
| | - David M Fields
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States of America
| | - Reidun M Bjelland
- Austevoll Research Station, Institute of Marine Research, Storebø, Norway
| | - Vera B S Chan
- LEMAR, Institut Français de Recherche pour l'Exploitation de la Mer, UMR 6539 (UBO/CNRS/IRD/Ifremer), Plouzané, France
| | - Caroline M F Durif
- Austevoll Research Station, Institute of Marine Research, Storebø, Norway
| | - Andrew Mount
- Department of Biological Sciences, Clemson University, Clemson, SC, United States of America
| | - Jeffrey A Runge
- School of Marine Sciences, University of Maine, Orono, ME, United States of America.,Gulf of Maine Research Institute, Portland, ME, United States of America
| | - Steven D Shema
- Austevoll Research Station, Institute of Marine Research, Storebø, Norway
| | | | - Howard I Browman
- Austevoll Research Station, Institute of Marine Research, Storebø, Norway
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96
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Bechmann RK, Arnberg M, Gomiero A, Westerlund S, Lyng E, Berry M, Agustsson T, Jager T, Burridge LE. Gill damage and delayed mortality of Northern shrimp (Pandalus borealis) after short time exposure to anti-parasitic veterinary medicine containing hydrogen peroxide. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 180:473-482. [PMID: 31121554 DOI: 10.1016/j.ecoenv.2019.05.045] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 06/09/2023]
Abstract
Hydrogen peroxide (H2O2) is used as anti-parasitic veterinary medicine in salmon farms worldwide. In the period from 2009 to 2018 a total of 135 million kg of H2O2 was used in Norway, the world's largest producer of Atlantic salmon. Since the treatment water is discharged to the sea, concerns have been raised about effects of H2O2 on the coastal ecosystem. In the present study, Northern shrimp (Pandalus borealis) have been exposed to short pulses of H2O2 in the PARAMOVE® formulation, followed by a recovery period in clean seawater. The exposure concentrations represented 100, 1000 and 10 000 times dilutions of the prescribed treatment concentration for salmon; 15 mg/L, 1.5 mg/L and 0.15 mg/L H2O2. Significantly increased mortality was observed after 2 h exposure to 15 mg/L H2O2 (50%) and after 2 h exposure to 1.5 mg/L H2O2 on 3 consecutive days (33%), but no mortality was observed after 2 h exposure to 0.15 mg/L. The mortality occurred 2-4 days after the first pulse of exposure. The patterns of acute effects (immobility and death) could be captured with a toxicokinetic-toxicodynamic model (GUTS), which allows extrapolations to LC50s for constant exposure, or thresholds for effects given untested exposure profiles. Effects of H2O2 were also detected in shrimp that survived until the end of the recovery period. The feeding rate was 66% lower than in the control after 12 days of recovery for the three-pulse 1.5 mg/L exposure. Furthermore, dose dependent tissue damage was detected in the gills and evidence of lipid peroxidation in the hepatopancreas in shrimp exposed for 1 h to 1.5 mg/L and 15 mg/L and kept in recovery for 8 days. Fluorescence intensity in the hepatopancreas of treated shrimp increased 47% and 157% at 1.5 mg/L and 15 mg/L, respectively, compared to the control. Local hydrodynamic conditions will determine how fast the concentration of H2O2 will be diluted and how far it will be transported horizontally and vertically. Results from dispersion modelling (literature data) together with the current experiments indicate that treatment water with toxic concentrations of H2O2 (1.5 mg/L) could reach P. borealis living more than 1 km from a treated salmon farm.
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Affiliation(s)
| | - Maj Arnberg
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | - Alessio Gomiero
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | - Stig Westerlund
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | - Emily Lyng
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | - Mark Berry
- NORCE Norwegian Research Centre, Mekjarvik 12, 4072, Randaberg, Norway.
| | | | | | - Les E Burridge
- Burridge Consulting Inc., 61 Emmalee Dr Stratford PE, Canada, C1B 0B5, Canada.
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97
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Effects of chitin synthesis inhibitor treatment on Lepeophtheirus salmonis (Copepoda, Caligidae) larvae. PLoS One 2019; 14:e0222520. [PMID: 31545833 PMCID: PMC6756749 DOI: 10.1371/journal.pone.0222520] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 09/02/2019] [Indexed: 01/30/2023] Open
Abstract
The salmon louse (Lepeophtheirus salmonis) is an ectoparasite infecting Atlantic salmon (Salmo salar), which causes substantial problems to the salmon aquaculture and threatens wild salmon. Chitin synthesis inhibitors (CSIs) are used to control L. salmonis in aquaculture. CSIs act by interfering with chitin formation and molting. In the present study, we investigated the action of four CSIs: diflubenzuron (DFB), hexaflumuron (HX), lufenuron (LF), and teflubenzuron (TFB) on larval molt. As the mode of action of CSIs remains unknown, we selected key enzymes in chitin metabolism and investigated if CSI treatment influenced the transcriptional level of these genes. All four CSIs interfered with the nauplius II molt to copepodids in a dose-dependent manner. The EC50 values were 93.2 nM for diflubenzuron, 1.2 nM for hexaflumuron, 22.4 nM for lufenuron, and 11.7 nM for teflubenzuron. Of the investigated genes, only the transcriptional level of L. salmonis chitin synthase 1 decreased significantly in hexaflumuron and diflubenzuron-treated larvae. All the tested CSIs affected the molt of nauplius II L. salmonis larvae but at different concentrations. The larvae were most sensitive to hexaflumuron and less sensitive to diflubenzuron. None of the CSIs applied had a strong impact on the transcriptional level of chitin synthesis or chitinases genes in L. salmonis. Further research is necessary to get more knowledge of the nature of the inhibition of CSI and may require methods such as studies of protein structure and enzymological studies.
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98
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Chakraborty S, Cao T, Hossain A, Gnanagobal H, Vasquez I, Boyce D, Santander J. Vibrogen-2 vaccine trial in lumpfish (Cyclopterus lumpus) against Vibrio anguillarum. JOURNAL OF FISH DISEASES 2019; 42:1057-1064. [PMID: 31087342 DOI: 10.1111/jfd.13010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/04/2019] [Accepted: 04/06/2019] [Indexed: 06/09/2023]
Abstract
Lumpfish (Cyclopterus lumpus), a native fish of the North Atlantic Ocean, is utilized as cleaner fish to biocontrol sea lice infestations in Atlantic salmon aquaculture. However, bacterial infections are affecting cleaner fish performance. Vibrio anguillarum, the aetiological agent of vibriosis, is one of the most frequent bacterial infections in lumpfish, and effective vaccine programmes against this pathogen have been identified as a high priority for lumpfish. Vibrogen-2 is a commercial polyvalent bath vaccine that contains formalin-inactivated cultures of V. anguillarum serotypes O1 and O2, and Vibrio ordalii. In this study, we evaluated Vibrogen-2 efficacy in lumpfish against a local isolated V. anguillarum strain. Two groups of 125 lumpfish were bath-immunized, bath-boost-immunized at four weeks post-primary immunization, and intraperitoneally (i.p.) boost-immunized at eight weeks post-primary immunization. The control groups were i.p. mock-immunized with PBS. Twenty-seven weeks post-primary immunization, the fish were i.p. challenged with 10 or 100 times the V. anguillarum J360 LD50 dose. After the challenge, survival was monitored daily, and samples of tissues were collected at ten days post-challenge. Commercial vaccine Vibrogen-2 reduced V. anguillarum tissue colonization and delayed mortality but did not confer immune protection to C. lumpus against the V. anguillarum i.p. challenge.
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Affiliation(s)
- Setu Chakraborty
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Faculty of Science, Memorial University of Newfoundland, St John's, Newfoundland, Canada
| | - Trung Cao
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Faculty of Science, Memorial University of Newfoundland, St John's, Newfoundland, Canada
| | - Ahmed Hossain
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Faculty of Science, Memorial University of Newfoundland, St John's, Newfoundland, Canada
| | - Hajarooba Gnanagobal
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Faculty of Science, Memorial University of Newfoundland, St John's, Newfoundland, Canada
| | - Ignacio Vasquez
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Faculty of Science, Memorial University of Newfoundland, St John's, Newfoundland, Canada
| | - Danny Boyce
- Dr. Joe Brown Aquatic Research Building, Department of Ocean Sciences, Memorial University of Newfoundland, St John's, Newfoundland, Canada
| | - Javier Santander
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Faculty of Science, Memorial University of Newfoundland, St John's, Newfoundland, Canada
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99
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Pietrak M, Jensen A, Barbin Zydlewski G, Bricknell I. The Three-spined Stickleback, Gasterosteus aculeatus Linnaeus 1758, plays a minor role as a host of Lepeophtheirus salmonis (Krøyer 1837) in the Gulf of Maine. JOURNAL OF FISH DISEASES 2019; 42:985-989. [PMID: 31044445 DOI: 10.1111/jfd.12998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
The sea louse, Lepeophtheirus salmonis (Krøyer 1837), is a significant parasite of farmed salmon throughout the Northern Hemisphere. Management of on-farm louse populations can be improved by understanding the role that wild fish play in sustaining and providing refuge for the local population of sea lice. In this study, 1,064 sticklebacks were captured. Of these animals, 176 individuals were carrying a total of 238 sea lice, yielding a prevalence and intensity of 16.5% and 1.4 lice per fish, respectively. Detailed examination of the sea lice on the three-spined sticklebacks captured in Cobscook Bay found two L. salmonis individuals using three-spined sticklebacks as hosts. A 2012 survey of wild fish in Cobscook Bay, Maine, found multiple wild hosts for Caligus elongatus (von Nordmann 1832), including three-spined sticklebacks (Gasterosteus aculeatus L.), but no L. salmonis were found in this earlier study.
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Affiliation(s)
- Michael Pietrak
- USDA, Agricultural Research Service, National Cold Water Marine Aquaculture Center, Franklin, Maine
| | - Alexander Jensen
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan
- School of Marine Sciences, University of Maine, Orono, Maine
| | | | - Ian Bricknell
- School of Marine Sciences, University of Maine, Orono, Maine
- USA Aquaculture Research Institute, University of Maine, Orono, Maine
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100
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Heggland EI, Tröße C, Eichner C, Nilsen F. Heavy and light chain homologs of ferritin are essential for blood-feeding and egg production of the ectoparasitic copepod Lepeophtheirus salmonis. Mol Biochem Parasitol 2019; 232:111197. [PMID: 31251953 DOI: 10.1016/j.molbiopara.2019.111197] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 06/13/2019] [Accepted: 06/19/2019] [Indexed: 12/21/2022]
Abstract
The salmon louse, Lepeophtheirus salmonis, is a hematophagous ectoparasite of salmonid fish. Due to its blood-feeding activity, the louse is exposed to great amounts of iron, which is an essential, yet potentially toxic mineral. The major known iron storage protein is ferritin, which the salmon louse encodes four genes of (LsFer1-4). Two of the ferritins are predicted to be secreted. These are one of the heavy chain homologs (LsFer1) and the light chain homolog (LsFer2). Here, we perform functional studies and characterize the two secreted ferritins. Our results show that knocking down LsFer1 and LsFer2 both negatively affect the parasite's physiology, as it is not able to properly feed and reproduce. In a starvation experiment, the transcript levels of both LsFer1 and LsFer2 decrease during the starvation period. Combined, these results demonstrate the importance of these genes for the normal parasite biology, and they could thus potentially be targets for pest management.
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Affiliation(s)
- Erna Irene Heggland
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Norway.
| | | | - Christiane Eichner
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Norway
| | - Frank Nilsen
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Norway
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