101
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Tarrant AM, Nilsson B, Hansen BW. Molecular physiology of copepods - from biomarkers to transcriptomes and back again. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2019; 30:230-247. [DOI: 10.1016/j.cbd.2019.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/14/2019] [Accepted: 03/16/2019] [Indexed: 12/31/2022]
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102
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Michaud DR, Poley JD, Fast MD. Sex-biased gene expression and evolution of candidate reproductive transcripts in adult stages of salmon lice (Lepeophtheirus salmonis). Facets (Ott) 2019. [DOI: 10.1139/facets-2018-0016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The salmon louse Lepeophtheirus salmonis (Krøyer 1837) displays numerous sexually dimorphic characteristics. Insights into their underlying molecular components have only recently been explored, which serve to better understand both the basic biology of the louse, associated impacts on drug sensitivity, and evolution of resistance. Expression of 16 L. salmonis genes putatively involved in sexual dimorphism and reproduction were used to determine differences between sexes and better understand responses to mating using RT-qPCR of pre-adult and adult lice. Analysis of these genes revealed the dynamic nature of sex-biased expression across stages. However, female reception of a spermatophore did not appear to impact the expression of these particular genes. Furthermore six of these transcripts and 84 others identified previously in a large-scale louse transcriptomics experiment were used to estimate differences in evolutionary rates and codon-usage bias of sex-related genes using phylogenetic analysis by maximum likelihood (PAML) and codonW. Results suggest male-biased genes are evolving at significantly greater rates than female-biased and unbiased genes as evidenced by higher rates of non-synonymous substitutions and lower codon-usage bias in these genes. These analyses expand our understanding of interactions of sex-biased expression across the pre-adult and adult life stages and provide foundations for better understanding evolutionary differences in sex-biased genes of L. salmonis.
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Affiliation(s)
- Dylan R. Michaud
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, UPEI, Charlottetown, PE C1A 4P3, Canada
| | - Jordan D. Poley
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, UPEI, Charlottetown, PE C1A 4P3, Canada
- Center for Aquaculture Technologies Canada, 20 Hope Street, Souris PE C0A 2B0, Canada
| | - Mark D. Fast
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, UPEI, Charlottetown, PE C1A 4P3, Canada
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103
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Komisarczuk AZ, Kongshaug H, Li M, Nilsen F. RNAi mediated myosuppressin deficiency affects muscle development and survival in the salmon louse (Lepeophtheirus salmonis). Sci Rep 2019; 9:6944. [PMID: 31061463 PMCID: PMC6502818 DOI: 10.1038/s41598-019-43515-w] [Citation(s) in RCA: 5] [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: 10/04/2018] [Accepted: 04/23/2019] [Indexed: 12/05/2022] Open
Abstract
Muscle activity is regulated by stimulatory and inhibitory neuropeptides allowing for contraction and relaxation. In Arthropods, one of the important myoinhibitors is Myosuppressin, belonging to FMRFamide-like peptides, that was shown to have inhibitory effects on visceral muscle contraction and to regulate vital physiological processes including reproduction or feeding. We have identified myosuppressin in salmon louse Lepeophtheirus salmonis (LsalMS) and systematically characterised its function and complex abnormalities emerging after LsalMS knockdown by RNAi in all developmental stages in this species. Immunohistochemistry analysis localized the LsalMS mainly to the central nervous system, but also to the vital organs within the alimentary tract and the reproductive system. The most striking feature of LsalMS deficiency during lice development was severe reduction of the muscle content, with abnormalities detected in both the visceral and skeletal muscles. Moreover, down-regulation of LsalMS affects moulting, spermatophore deposition and feeding by affecting development of the intestinal wall and increasing its contraction frequency.
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Affiliation(s)
- Anna Z Komisarczuk
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgate 53 A/B, 5008, Bergen, Norway.
| | - Heidi Kongshaug
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgate 53 A/B, 5008, Bergen, Norway
| | - Ming Li
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Frank Nilsen
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgate 53 A/B, 5008, Bergen, Norway
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104
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Sievers M, Oppedal F, Ditria E, Wright DW. The effectiveness of hyposaline treatments against host-attached salmon lice. Sci Rep 2019; 9:6976. [PMID: 31061506 PMCID: PMC6502938 DOI: 10.1038/s41598-019-43533-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 04/17/2019] [Indexed: 11/27/2022] Open
Abstract
Understanding how salinity affects marine parasites is vital to understanding their ecology and treatment, particularly for host-parasite systems that traverse marine and freshwater realms such as the globally important Atlantic salmon (Salmo salar), salmon louse (Lepeophtheirus salmonis) system. Growing concerns for wild fish populations, and decreased efficiencies and burgeoning costs of lice treatments for farmed fish has necessitated more environmentally and socially acceptable delousing procedures, such as hyposaline treatments. The effect of brackish water on L. salmonis following primary attachment is largely unknown, with experimental evidence derived mostly from unattached or newly attached copepodids, or adult stages. We aimed to understand how attached lice respond to hyposaline environments to assess effectiveness as a parasite management strategy and to help better define delousing areas used by wild fish. Louse development at 4, 12, 19 and 26 ppt, and survival at 4 ppt, decreased as exposure times increased, but survival was otherwise unaffected. Subjecting salmon to fluctuating, repeat exposures did not influence efficacy. We confirm that free-swimming stages are susceptible, and show that attached copepodids were more tolerant than previously predicted based on experiments on alternate development stages. These results improve our understanding of the utility of hyposaline treatments in aquaculture and self-treating in wild fish, and could apply to other fish-lice parasite systems. Further, these data are important for models predicting host-parasite interactions and can contribute to predictive models on the transmission dynamics of sea lice from farm to wild fish.
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Affiliation(s)
- Michael Sievers
- Institute of Marine Research, 5984, Matredal, Norway. .,Australian Rivers Institute - Coast and Estuaries, Griffith University, Gold Coast, 4222, Queensland, Australia. .,Australian Rivers Institute - Coast and Estuaries, Griffith University, Gold Coast, 4222, Queensland, Australia.
| | - Frode Oppedal
- Institute of Marine Research, 5984, Matredal, Norway
| | - Ellen Ditria
- Institute of Marine Research, 5984, Matredal, Norway.,Australian Rivers Institute - Coast and Estuaries, Griffith University, Gold Coast, 4222, Queensland, Australia.,Australian Rivers Institute - Coast and Estuaries, Griffith University, Gold Coast, 4222, Queensland, Australia
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105
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Junquera P, Hosking B, Gameiro M, Macdonald A. Benzoylphenyl ureas as veterinary antiparasitics. An overview and outlook with emphasis on efficacy, usage and resistance. Parasite 2019; 26:26. [PMID: 31041897 PMCID: PMC6492539 DOI: 10.1051/parasite/2019026] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/11/2019] [Indexed: 01/17/2023] Open
Abstract
Six benzoylphenyl ureas are currently used in formulations approved as veterinary medicines: diflubenzuron for fly control mainly on cattle, lice and blowfly strike control on sheep, and lice control on farmed salmonids; lufenuron for flea control on dogs and cats and for lice control on farmed salmonids; triflumuron for lice and blowfly strike control on sheep; fluazuron for tick control on cattle; teflubenzuron for lice control on farmed salmon; and novaluron for fly and tick control on cattle and for flea control on dogs. Resistance to diflubenzuron and triflumuron has already been reported for sheep body lice and blowflies, and to fluazuron in cattle ticks. These and other minor veterinary usages, as well as the current status of resistance, are reviewed and perspectives for future opportunities are discussed based on unexplored potentials and threats posed by future resistance development.
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Affiliation(s)
| | - Barry Hosking
-
Elanco Australasia Pty. Limited Kemps Creek 2178
NSW Australia
| | - Marta Gameiro
-
Elanco Canada Limited 150 Research Lane, Suite 120 Guelph ON
N1G 4T2 Canada
| | - Alicia Macdonald
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Elanco Canada Limited 150 Research Lane, Suite 120 Guelph ON
N1G 4T2 Canada
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106
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Heggland EI, Eichner C, Støve SI, Martinez A, Nilsen F, Dondrup M. A scavenger receptor B (CD36)-like protein is a potential mediator of intestinal heme absorption in the hematophagous ectoparasite Lepeophtheirus salmonis. Sci Rep 2019; 9:4218. [PMID: 30862948 PMCID: PMC6414551 DOI: 10.1038/s41598-019-40590-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 02/19/2019] [Indexed: 02/01/2023] Open
Abstract
Intestinal absorption of heme has remained enigmatic for years, even though heme provides the most bioavailable form of iron. The salmon louse, Lepeophtheirus salmonis, is a heme auxotrophic ectoparasite feeding on large quantities of blood from its host, the salmon. Here we show that a scavenging CD36-like receptor is a potential mediator of heme absorption in the intestine of the salmon louse. The receptor was characterized by a heme binding assay using recombinantly expressed protein, in situ hybridization and immunohistochemistry, as well as functional knockdown studies in the louse. A computational structural model of the receptor predicted a binding pocket for heme, as also supported by in silico docking. The mRNA and protein were expressed exclusively in the intestine of the louse. Further, knocking down the transcript resulted in lower heme levels in the adult female louse, production of shorter egg strings, and an overall lower hatching success of the eggs. Finally, starving the lice caused the transcript expression of the receptor to decrease. To our knowledge, this is the first time a CD36-like protein has been suggested to be an intestinal heme receptor.
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Affiliation(s)
- Erna Irene Heggland
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Christiane Eichner
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Svein Isungset Støve
- Department of Biomedicine & K.G. Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
| | - Aurora Martinez
- Department of Biomedicine & K.G. Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
| | - Frank Nilsen
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Michael Dondrup
- Department of Informatics & Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway.
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107
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Mancilla-Schulz J, Marín SL, Molinet C. Dynamics of Caligus rogercresseyi (Boxshall & Bravo, 2000) in farmed Atlantic salmon (Salmo salar) in southern Chile: Are we controlling sea lice? JOURNAL OF FISH DISEASES 2019; 42:357-369. [PMID: 30644118 DOI: 10.1111/jfd.12931] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/19/2018] [Accepted: 10/22/2018] [Indexed: 06/09/2023]
Abstract
Caligus rogercresseyi generates the greatest losses in the salmon industry in Chile. The relationship between salmon farming and sea lice is made up of various components: the parasite, host, environment and farming practices, which make it difficult to identify patterns in parasite population dynamics to define prevention and control strategies. The objectives of this study were to analyse and compare the effect of farming, sanitary practices and environmental variables on the abundance of gravid females (GF) and juveniles (JUV) of C. rogercresseyi on Salmo salar in three Salmon Neighborhood Areas (SNAs) in Region 10, south of Chile. Linear mixed-effects models of the negative binomial distribution were used to evaluate the effect of the different explanatory variables on GF and JUV. Productive variables were the key drivers explaining the abundance of GF and JUV. Results suggest that C. rogercresseyi is not controlled and JUV are persistent in the three SNAs, and sanitary practices do not control the dissemination of the parasite among sites. Environmental variables had a low impact on sea lice abundance. There is a need to perform analysis for modelling of parasite population dynamics to improve Integrated Pest Management, including changes in the governance to achieve an effective prevention and control.
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Affiliation(s)
- Jorge Mancilla-Schulz
- Aquaculture Sciences, Universidad Austral de Chile, Puerto Montt, Chile
- Marine Harvest Chile, Puerto Montt, Chile
| | - Sandra L Marín
- Institute of Aquaculture, Universidad Austral de Chile, Puerto Montt, Chile
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Puerto Montt, Chile
| | - Carlos Molinet
- Institute of Aquaculture, Universidad Austral de Chile, Puerto Montt, Chile
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108
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Aldrin M, Jansen P, Stryhn H. A partly stage-structured model for the abundance of salmon lice in salmonid farms. Epidemics 2019; 26:9-22. [DOI: 10.1016/j.epidem.2018.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/12/2018] [Accepted: 08/16/2018] [Indexed: 11/28/2022] Open
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109
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McEwan GF, Groner ML, Cohen AAB, Imsland AKD, Revie CW. Modelling sea lice control by lumpfish on Atlantic salmon farms: interactions with mate limitation, temperature and treatment rules. DISEASES OF AQUATIC ORGANISMS 2019; 133:69-82. [PMID: 31089004 DOI: 10.3354/dao03329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Atlantic salmon farming is one of the largest aquaculture sectors in the world. A major impact on farm economics, fish welfare and, potentially, nearby wild salmonid populations, is the sea louse ectoparasite Lepeophtheirus salmonis. Sea louse infestations are most often controlled through application of chemicals, but in most farming regions, sea lice have evolved resistance to the small set of available chemicals. Therefore, alternative treatment methodologies are becoming more widely used. One increasingly common alternative treatment involves the co-culture of farmed salmon with cleaner fish, which prey on sea lice. However, despite their wide use, little is understood about the situations in which cleaner fish are most effective. For example, previous work suggests that a low parasite density results in sea lice finding it difficult to acquire mates, reducing fecundity and population growth. Other work suggests that environmental conditions such as temperature and external sea louse pressure have substantial impact on this mate limitation threshold and may even remove the effect entirely. We used an Agent-Based Model (ABM) to simulate cleaner fish on a salmon farm to explore interactions between sea louse mating behaviour, cleaner fish feeding rate, temperature and external sea louse pressure. We found that sea louse mating has a substantial effect on sea louse infestations under a variety of environmental conditions. Our results suggest that cleaner fish can control sea louse infestations most effectively by maintaining the population below critical density thresholds.
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Affiliation(s)
- Gregor F McEwan
- Department of Health Management, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada
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110
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Núñez-Acuña G, Gallardo-Escárate C. Characterization of the salmon louse Lepeophtheirus salmonis miRNome: Sex-biased differences related to the coding and non-coding RNA interplay. Mar Genomics 2019; 45:38-47. [PMID: 30772247 DOI: 10.1016/j.margen.2019.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 01/21/2019] [Accepted: 01/21/2019] [Indexed: 12/12/2022]
Abstract
The salmon louse Lepeophtheirus salmonis is a marine ectoparasite that has a detrimental impact on salmon farms. Genomic knowledge of adult stages is critical to understand the reproductive success and lifecycle completion of this species. Here, we report a comprehensive characterization of the L. salmonis miRNome with emphasis on the sex-differences of the parasite. Small-RNA sequencing was conducted on males and females, and mRNA-sequencing was also conducted to identify miRNA-targets at these stages. Based on bioinformatics analyses, 3101 putative miRNAs were found in L. salmonis, including precursors and variants. The most abundant and over-expressed miRNAs belonged to the bantam, mir-100, mir-1, mir-263a and mir-276 families, while the most differentially expressed mRNAs corresponded to genes related to reproduction and other biological processes involved in cell-differentiation. Target analyses revealed that the most up-regulated miRNAs in males can act by inhibiting the expression of genes related to female differentiation such as vitellogenin genes. Target prediction and expression patterns suggested a pivotal role of miRNAs in the reproductive development of L. salmonis.
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Affiliation(s)
- Gustavo Núñez-Acuña
- Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, Concepción, Chile
| | - Cristian Gallardo-Escárate
- Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, Concepción, Chile.
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111
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Robledo D, Gutiérrez AP, Barría A, Lhorente JP, Houston RD, Yáñez JM. Discovery and Functional Annotation of Quantitative Trait Loci Affecting Resistance to Sea Lice in Atlantic Salmon. Front Genet 2019; 10:56. [PMID: 30800143 PMCID: PMC6375901 DOI: 10.3389/fgene.2019.00056] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/23/2019] [Indexed: 12/22/2022] Open
Abstract
Sea lice (Caligus rogercresseyi) are ectoparasitic copepods which have a large negative economic and welfare impact in Atlantic salmon (Salmo salar) aquaculture, particularly in Chile. A multi-faceted prevention and control strategy is required to tackle lice, and selective breeding contributes via cumulative improvement of host resistance to the parasite. While host resistance has been shown to be heritable, little is yet known about the individual loci that contribute to this resistance, the potential underlying genes, and their mechanisms of action. In this study we took a multifaceted approach to identify and characterize quantitative trait loci (QTL) affecting host resistance in a population of 2,688 Caligus-challenged Atlantic salmon post-smolts from a commercial breeding program. We used low and medium density genotyping with imputation to collect genome-wide SNP marker data for all animals. Moderate heritability estimates of 0.28 and 0.24 were obtained for lice density (as a measure of host resistance) and growth during infestation, respectively. Three QTL explaining between 7 and 13% of the genetic variation in resistance to sea lice (as represented by the traits of lice density) were detected on chromosomes 3, 18, and 21. Characterisation of these QTL regions was undertaken using RNA sequencing and pooled whole genome sequencing data. This resulted in the identification of a shortlist of potential underlying causative genes, and candidate functional mutations for further study. For example, candidates within the chromosome 3 QTL include a putative premature stop mutation in TOB1 (an anti-proliferative transcription factor involved in T cell regulation) and an uncharacterized protein which showed significant differential allelic expression (implying the existence of a cis-acting regulatory mutation). While host resistance to sea lice is polygenic in nature, the results of this study highlight significant QTL regions together explaining between 7 and 13 % of the heritability of the trait. Future investigation of these QTL may enable improved knowledge of the functional mechanisms of host resistance to sea lice, and incorporation of functional variants to improve genomic selection accuracy.
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Affiliation(s)
- Diego Robledo
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh, United Kingdom
| | - Alejandro P. Gutiérrez
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh, United Kingdom
| | - Agustín Barría
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
| | | | - Ross D. Houston
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh, United Kingdom
| | - José M. Yáñez
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
- Núcleo Milenio INVASAL, Concepción, Chile
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112
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Urbina MA, Cumillaf JP, Paschke K, Gebauer P. Effects of pharmaceuticals used to treat salmon lice on non-target species: Evidence from a systematic review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 649:1124-1136. [PMID: 30308884 DOI: 10.1016/j.scitotenv.2018.08.334] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/23/2018] [Accepted: 08/24/2018] [Indexed: 05/22/2023]
Abstract
Aquaculture is currently one of the best prospects to help meet the growing need for protein in the human diet. However, aquaculture development and production result in consequences for the environment and also impact other productive activities. Salmon and trout cage culture has required the use of large quantities of pharmaceuticals in order to control outbreaks and the persistence of different pathogens, including sea lice (parasitic copepods), which cause economic losses of around 0.39 € Kg-1 of salmon produced. The pharmaceuticals currently used for the control of sea lice (cypermethrin, deltamethrin, azamethiphos, hydrogen peroxide) are applied by in situ immersion treatments, enclosing net pens using tarpaulin and then bathing fish with the pharmaceutical. After treatment the pharmaceuticals are released into the surrounding environment, exposing non-target species. Although the effects of such pharmaceutical exposure has been studied in some species, to date a systematic and exhaustive review of these potential effects has not yet been performed. In this study, an exhaustive review of the literature evaluating lethal and sub-lethal effects of anti-sea lice pharmaceuticals on non-target crustaceans and bivalves was performed, in order to assess the extent of the effects, toxicity, variables affecting such toxicity and identify potential synergistic effects previously unexplored. Our results show clear negative effects at concentrations lower than those used in treatments against sea lice in all of the species studied. Likewise, this study demonstrates knowledge gaps that need to be addressed in order to improve our understanding of the effects of these pharmaceuticals on non-target species, ecosystems in general and other productive activities.
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Affiliation(s)
- M A Urbina
- Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Chile.
| | - J P Cumillaf
- Instituto de Acuicultura, Universidad Austral de Chile, Casilla 1327, Puerto Montt, Chile; Programa de Doctorado en Ciencias de la Acuicultura, Universidad Austral de Chile, Los Pinos s/n, Balneario Pelluco, Puerto Montt, Chile
| | - K Paschke
- Instituto de Acuicultura, Universidad Austral de Chile, Casilla 1327, Puerto Montt, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Chile
| | - P Gebauer
- Centro i~mar, Universidad de Los Lagos, Camino Chinquihue Km 6, Puerto Montt, Chile
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113
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Carmona-Antoñanzas G, Helgesen KO, Humble JL, Tschesche C, Bakke MJ, Gamble L, Bekaert M, Bassett DI, Horsberg TE, Bron JE, Sturm A. Mutations in voltage-gated sodium channels from pyrethroid resistant salmon lice (Lepeophtheirus salmonis). PEST MANAGEMENT SCIENCE 2019; 75:527-536. [PMID: 30062864 DOI: 10.1002/ps.5151] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 06/22/2018] [Accepted: 07/19/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Parasitic salmon lice (Lepeophtheirus salmonis) cause high economic losses in Atlantic salmon farming. Pyrethroids, which block arthropod voltage-gated sodium channels (Nav 1), are used for salmon delousing. However, pyrethroid resistance is common in L. salmonis. The present study characterized Nav 1 homologues in L. salmonis in order to identify channel mutations associated to resistance, called kdr (knockdown) mutations. RESULTS Genome scans identified three L. salmonis Nav 1 homologues, LsNav 1.1, LsNav 1.2 and LsNav 1.3. Arthropod kdr mutations map to specific Nav 1 regions within domains DI-III, namely segments S5 and S6 and the linker helix connecting S4 and S5. The above channel regions were amplified by RT-PCR and sequenced in deltamethrin-susceptible and deltamethrin-resistant L. salmonis. While LsNav 1.1 and LsNav 1.2 lacked nucleotide polymorphisms showing association to resistance, LsNav 1.3 showed a non-synonymous mutation in S5 of DII occurring in deltamethrin-resistant parasites. The mutation is homologous to a previously described kdr mutation (I936V, numbering according to Musca domestica Vssc1) and was present in two pyrethroid-resistant L. salmonis strains (allele frequencies of 0.800 and 0.357), but absent in two pyrethroid-susceptible strains. CONCLUSIONS The present study indicates that a kdr-mutation in LsNaV 1.3 may contribute to deltamethrin resistance in L. salmonis. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Greta Carmona-Antoñanzas
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
- Imegen, Parc Científic de la Universitat de València, Paterna, Spain
| | - Kari O Helgesen
- Department of Epidemiology, Norwegian Veterinary Institute, Oslo, Norway
| | - Joseph L Humble
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - Claudia Tschesche
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - Marit J Bakke
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Sea Lice Research Centre, Oslo, Norway
| | - Louise Gamble
- 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
| | - Tor E Horsberg
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Sea Lice Research Centre, Oslo, Norway
| | - 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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114
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Samsing F, Johnsen I, Treml EA, Dempster T. Identifying 'firebreaks' to fragment dispersal networks of a marine parasite. Int J Parasitol 2019; 49:277-286. [PMID: 30660636 DOI: 10.1016/j.ijpara.2018.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 11/02/2018] [Accepted: 11/03/2018] [Indexed: 10/27/2022]
Abstract
Marine ecosystems are beset by disease outbreaks, and efficient strategies to control dispersal of pathogens are scarce. We tested whether introducing no-farming areas or 'firebreaks' could disconnect dispersal networks of a parasitic disease affecting the world's largest marine fish farming industry (∼1000 farms). Larval salmon lice (Lepeophtheirus salmonis) are released from and transported among salmon farms by ocean currents, creating inter-farm networks of louse dispersal. We used a state-of-the-art biophysical model to predict louse movement along the Norwegian coastline and network analysis to identify firebreaks to dispersal. At least one firebreak that fragmented the network into two large unconnected groups of farms was identified for all seasons. During spring, when wild salmon migrate out into the ocean, and louse levels per fish at farms must be minimised, two effective firebreaks were created by removing 13 and 21 farms (1.3% and 2.2% of all farms in the system) at ∼61°N and 67°N, respectively. We have demonstrated that dispersal models coupled with network analysis can identify no-farming zones that fragment dispersal networks. Reduced dispersal pathways should lower infection pressure at farms, slow the evolution of resistance to parasite control measures, and alleviate infection pressure on wild salmon populations.
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Affiliation(s)
- Francisca Samsing
- School of BioSciences, University of Melbourne, 3010 Victoria, Australia; CSIRO, Castray Esplanade, Hobart 7004 TAS, Australia.
| | - Ingrid Johnsen
- Institute of Marine Research, P.O. Box 1870 Nordnes, N-5817 Bergen, Norway
| | - Eric A Treml
- School of BioSciences, University of Melbourne, 3010 Victoria, Australia; School of Life and Environmental Sciences, Deakin University, Victoria 3220, Australia
| | - Tim Dempster
- School of BioSciences, University of Melbourne, 3010 Victoria, Australia
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115
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Harðardóttir HM, Male R, Nilsen F, Eichner C, Dondrup M, Dalvin S. Chitin synthesis and degradation in Lepeophtheirus salmonis: Molecular characterization and gene expression profile during synthesis of a new exoskeleton. Comp Biochem Physiol A Mol Integr Physiol 2019; 227:123-133. [DOI: 10.1016/j.cbpa.2018.10.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023]
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116
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Guðmundsdóttir S, Vendramin N, Cuenca A, Sigurðardóttir H, Kristmundsson A, Iburg TM, Olesen NJ. Outbreak of viral haemorrhagic septicaemia (VHS) in lumpfish (Cyclopterus lumpus) in Iceland caused by VHS virus genotype IV. JOURNAL OF FISH DISEASES 2019; 42:47-62. [PMID: 30397920 PMCID: PMC7379627 DOI: 10.1111/jfd.12910] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 08/31/2018] [Accepted: 09/05/2018] [Indexed: 06/01/2023]
Abstract
A novel viral haemorrhagic septicaemia virus (VHSV) of genotype IV was isolated from wild lumpfish (Cyclopterus lumpus), brought to a land-based farm in Iceland, to serve as broodfish. Two groups of lumpfish juveniles, kept in tanks in the same facility, got infected. The virus isolated was identified as VHSV by ELISA and real-time RT-PCR. Phylogenetic analysis, based on the glycoprotein (G) gene sequences, may indicate a novel subgroup of VHSV genotype IV. In controlled laboratory exposure studies with this new isolate, there was 3% survival in the I.P. injection challenged group while there was 90% survival in the immersion group. VHSV was not re-isolated from fish challenged by immersion. In a cohabitation trial, lumpfish infected I.P. (shedders) were placed in tanks with naïve lumpfish as well as naïve Atlantic salmon (Salmo salar L.). 10% of the lumpfish shedders and 43%-50% of the cohabiting lumpfish survived after 4 weeks. 80%-92% of the Atlantic salmon survived, but no viral RNA was detected by real-time RT-PCR nor VHSV was isolated from Atlantic salmon. This is the first isolation of a notifiable virus in Iceland and the first report of VHSV of genotype IV in European waters.
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Affiliation(s)
- Sigríður Guðmundsdóttir
- Fish Disease LaboratoryInstitute for Experimental PathologyUniversity of IcelandReykjavíkIceland
| | - Niccoló Vendramin
- European Union Reference Laboratory for Fish DiseasesNational Institute for Aquatic ResourcesTechnical University of DenmarkCopenhagenDenmark
| | - Argelia Cuenca
- European Union Reference Laboratory for Fish DiseasesNational Institute for Aquatic ResourcesTechnical University of DenmarkCopenhagenDenmark
| | - Heiða Sigurðardóttir
- Fish Disease LaboratoryInstitute for Experimental PathologyUniversity of IcelandReykjavíkIceland
| | - Arni Kristmundsson
- Fish Disease LaboratoryInstitute for Experimental PathologyUniversity of IcelandReykjavíkIceland
| | - Tine Moesgaard Iburg
- European Union Reference Laboratory for Fish DiseasesNational Institute for Aquatic ResourcesTechnical University of DenmarkCopenhagenDenmark
| | - Niels Jørgen Olesen
- European Union Reference Laboratory for Fish DiseasesNational Institute for Aquatic ResourcesTechnical University of DenmarkCopenhagenDenmark
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117
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Dessen J, Mørkøre T, Bildøy JI, Johnsen SN, Poppe LT, Hatlen B, Thomassen MS, Rørvik K. Increased dietary protein-to-lipid ratio improves survival during naturally occurring pancreas disease in Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2019; 42:21-34. [PMID: 30311660 PMCID: PMC6988130 DOI: 10.1111/jfd.12904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 08/30/2018] [Accepted: 09/05/2018] [Indexed: 06/08/2023]
Abstract
This study demonstrated that increased dietary protein-to-lipid ratio (P/L-ratio) improved survival of farmed Atlantic salmon naturally affected by pancreas disease (PD). In addition to diet, body weight (BW) and delousing mortality prior to the PD outbreak also contributed significantly (p < 0.05) to explain the observed variation in PD-associated mortality. Subsequent to the PD outbreak, large amount of fish failed to grow and caused thin fish with poor condition (runts). At the end of the trial, significantly (p < 0.05) lower amounts of runt fish and increased amount of superior graded fish where detected among fish fed increased P/L-ratio and within the fish with the largest BWs prior to PD. Diet, BW and delousing mortality contributed significantly (p < 0.05) to explain the variation in the amount of superior graded fish, whereas BW and diet explained the variation in the amount of runt fish. A significant (p < 0.01) negative linear relationship was observed between the amount of superior graded fish and the total mortality, whereas a positive linear relationship was detected between percentage of fillets with melanin and the total mortality. Thus, increased dietary P/L-ratio seem to reduce the mortality and impaired slaughter quality associated with PD.
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Affiliation(s)
- Jens‐Erik Dessen
- NofimaÅsNorway
- Department of Animal and Aquaculture SciencesNorwegian University of Life SciencesÅsNorway
| | - Turid Mørkøre
- NofimaÅsNorway
- Department of Animal and Aquaculture SciencesNorwegian University of Life SciencesÅsNorway
| | | | | | | | | | - Magny S. Thomassen
- Department of Animal and Aquaculture SciencesNorwegian University of Life SciencesÅsNorway
| | - Kjell‐Arne Rørvik
- NofimaÅsNorway
- Department of Animal and Aquaculture SciencesNorwegian University of Life SciencesÅsNorway
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118
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Danzmann RG, Norman JD, Rondeau EB, Messmer AM, Kent MP, Lien S, Igboeli O, Fast MD, Koop BF. A genetic linkage map for the salmon louse (Lepeophtheirus salmonis): evidence for high male:female and inter-familial recombination rate differences. Mol Genet Genomics 2018; 294:343-363. [PMID: 30460550 DOI: 10.1007/s00438-018-1513-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 10/15/2018] [Indexed: 01/28/2023]
Abstract
A salmon louse (Lepeophtheirus salmonis salmonis) genetic linkage map was constructed to serve as a genomic resource for future investigations into the biology of this important marine parasitic copepod species, and to provide insights into the inheritance patterns of genetic markers in this species. SNP genotyping of 8 families confirmed the presence of 15 linkage groups based upon the assignment of 93,773 markers. Progeny sample size weight adjusted map sizes in males (with the exception of SL12 and SL15) ranged in size from 96.50 cM (SL11) to 134.61 cM (SL06), and total combined map steps or bins ranged from 143 (SL09) to 203 (SL13). The SL12 male map was the smallest linkage group with a weight-averaged size of 3.05 cM with 6 recombination bins. Male:female specific recombination rate differences are 10.49:1 and represent one of the largest reported sex-specific differences for any animal species. Recombination ratio differences (M:F) ranged from 1.0 (SL12) to 29:1 (SL15). The number of markers exhibiting normal Mendelian segregation within the sex linkage group SL15 was extremely low (N = 80) in comparison to other linkage groups genotyped [range: 1459 (SL12)-10206 markers (SL05)]. Re-evaluation of Mendelian inheritance patterns of markers unassigned to any mapping parent according to hemizygous segregation patterns (models presented) identified matches for many of these markers to hemizygous patterns. The greatest proportion of these markers assigned to SL15 (N increased to 574). Inclusion of the hemizygous markers revised SL15 sex-specific recombination rate differences to 28:1. Recombination hot- and coldspots were identified across all linkage groups with all linkage groups possessing multiple peaks. Nine of 13 linkage groups evaluated possessed adjacent domains with hot-coldspot transitional zones. The most common pattern was for one end of the linkage to show elevated recombination in addition to internal regions. For SL01 and SL06, however, a terminal region with high recombination was not evident while a central domain possessing extremely high-recombination levels was present. High levels of recombination were weakly coupled to higher levels of SNP variation within domains, but this association was very strong for the central domains of SL01 and SL06. From the pooled paternal half-sib lots (several virgin females placed with 1 male), only 1 or two surviving family lots were obtained. Surviving families possessed parents where both the male and female possessed either inherently low or high recombination rates. This study provides insight into the organization of the sea louse genome, and describes large differences in recombination rate that exist among individuals of the same sex, and between the sexes. These differences in recombination rate may be coupled to the capabilities of this species to adapt to environmental and pharmaceutical treatments, given that family survivorship appears to be enhanced when parents have similar recombination levels.
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Affiliation(s)
- Roy G Danzmann
- Department of Integrative Biology, College of Biological Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
| | - Joseph D Norman
- Department of Integrative Biology, College of Biological Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.,The Hospital for Sick Children, 686 Bay St., Toronto, ON, M5G 0A4, Canada
| | - Eric B Rondeau
- Department of Biology, Centre for Biomedical Research, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8W 3N5, Canada
| | - Amber M Messmer
- Department of Biology, Centre for Biomedical Research, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8W 3N5, Canada
| | - Matthew P Kent
- Department of Animal and Aquacultural Sciences, Centre for Integrative Genetics (CIGENE), Norwegian University of Life Sciences, 1432, As, Norway
| | - Sigbjørn Lien
- Department of Animal and Aquacultural Sciences, Centre for Integrative Genetics (CIGENE), Norwegian University of Life Sciences, 1432, As, Norway
| | - Okechukwu Igboeli
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, PEI, C1A 4P3, Canada
| | - Mark D Fast
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave., Charlottetown, PEI, C1A 4P3, Canada
| | - Ben F Koop
- Department of Biology, Centre for Biomedical Research, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8W 3N5, Canada
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119
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Whittaker BA, Consuegra S, Garcia de Leaniz C. Genetic and phenotypic differentiation of lumpfish ( Cyclopterus lumpus) across the North Atlantic: implications for conservation and aquaculture. PeerJ 2018; 6:e5974. [PMID: 30498640 PMCID: PMC6251346 DOI: 10.7717/peerj.5974] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/19/2018] [Indexed: 11/20/2022] Open
Abstract
Demand for lumpfish (Cyclopterus lumpus) has increased exponentially over the last decade, both for their roe, which is used as a caviar substitute, and increasingly also as cleaner fish to control sea lice in salmon farming. The species is classified as Near Threatened by the IUCN and there are growing concerns that over-exploitation of wild stocks and translocation of hatchery-reared lumpfish may compromise the genetic diversity of native populations. We carried out a comparative analysis of genetic and phenotypic variation across the species' range to estimate the level of genetic and phenotypic differentiation, and determined patterns of gene flow at spatial scales relevant to management. We found five genetically distinct groups located in the West Atlantic (USA and Canada), Mid Atlantic (Iceland), East Atlantic (Faroe Islands, Ireland, Scotland, Norway and Denmark), English Channel (England) and Baltic Sea (Sweden). Significant phenotypic differences were also found, with Baltic lumpfish growing more slowly, attaining a higher condition factor and maturing at a smaller size than North Atlantic lumpfish. Estimates of effective population size were consistently low across the North East Atlantic (Iceland, Faroe Islands and Norway), the area where most wild lumpfish are fished for their roe, and also for the aquaculture industry. Our study suggests that some lumpfish populations are very small and have low genetic diversity, which makes them particularly vulnerable to over-exploitation and genetic introgression. To protect them we advocate curtailing fishing effort, closing the breeding cycle of the species in captivity to reduce dependence on wild stocks, restricting the translocation of genetically distinct populations, and limiting the risk of farm escapes.
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Affiliation(s)
- Benjamin Alexander Whittaker
- Department of Biosciences, Centre for Sustainable Aquatic Research, Swansea University, Swansea, Wales, United Kingdom
| | - Sofia Consuegra
- Department of Biosciences, Centre for Sustainable Aquatic Research, Swansea University, Swansea, Wales, United Kingdom
| | - Carlos Garcia de Leaniz
- Department of Biosciences, Centre for Sustainable Aquatic Research, Swansea University, Swansea, Wales, United Kingdom
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120
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Ruane NM, Swords D, Morrissey T, Geary M, Hickey C, Collins EM, Geoghegan F, Swords F. Isolation of salmonid alphavirus subtype 6 from wild-caught ballan wrasse, Labrus bergylta (Ascanius). JOURNAL OF FISH DISEASES 2018; 41:1643-1651. [PMID: 30051469 DOI: 10.1111/jfd.12870] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/25/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
The use of cleaner fish as a biological control for sea lice in Atlantic salmon aquaculture has increased in recent years. Wild-caught wrasse are commonly used as cleaner fish in Europe. In Ireland, samples of wrasse from each fishing area are screened for potential pathogens prior to their deployment into sea cages. Salmonid alphavirus was isolated from a pooled sample of ballan wrasse, showing no signs of disease, caught from the NW of Ireland. Partial sequencing of the E2 and nsP3 genes showed that it was closely related to the previously reported SAV subtype 6. This represents only the second isolation of this subtype and the first from a wild fish species, namely ballan wrasse.
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Affiliation(s)
- Neil M Ruane
- Fish Health Unit, Marine Institute, County Galway, Ireland
| | - David Swords
- Fish Health Unit, Marine Institute, County Galway, Ireland
| | | | - Michelle Geary
- Fish Health Unit, Marine Institute, County Galway, Ireland
| | - Cathy Hickey
- Fish Health Unit, Marine Institute, County Galway, Ireland
| | | | | | - Fiona Swords
- Fish Health Unit, Marine Institute, County Galway, Ireland
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121
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Agusti-Ridaura C, Dondrup M, Horsberg TE, Leong JS, Koop BF, Bravo S, Mendoza J, Kaur K. Caligus rogercresseyi acetylcholinesterase types and variants: a potential marker for organophosphate resistance. Parasit Vectors 2018; 11:570. [PMID: 30376873 PMCID: PMC6208076 DOI: 10.1186/s13071-018-3151-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/14/2018] [Indexed: 12/17/2022] Open
Abstract
Background Control of the sea louse Caligus rogercresseyi in the Chilean salmonid industry is reliant on chemical treatments. Azamethiphos was introduced in 2013, although other organophosphates were previously used. In 2014, reduced sensitivity to azamethiphos was detected in the Los Lagos Region using bioassays. The main target of organophosphates is the enzyme acetylcholinesterase (AChE). Mutations in the AChE gene are the main cause of organophosphate resistance in arthropods, including other sea lice. In the present study, we aimed to characterize C. rogercresseyi AChE(s) gene(s) and to study the association between AChE variants and azamethiphos resistance in this sea louse species. Methods Samples of adult male and female C. rogercresseyi were collected in the Los Lagos Region in 2014. Twenty-four hour exposure bioassays with azamethiphos were performed to select sensitive and resistant lice. The full-length cDNA coding sequences encoding for two AChEs in C. rogercresseyi were molecularly characterized. One of the AChE genes was screened by direct sequencing in the azamethiphos-selected lice to search for variants. An additional louse sampling was performed before and after an azamethiphos treatment in the field in 2017 to validate the findings. Results The molecular analysis revealed two putative AChEs in C. rogercresseyi. In silico analysis and 3D modelling of the protein sequences identified both of them as invertebrate AChE type 1; they were named C. rogercresseyi AChE1a and 1b. AChE1a had the characteristics of the main synaptic AChE, while AChE1b lacked some of the important amino acids of a typical AChE. A missense change found in the main synaptic AChE (1a), F318F/V (F290 in Torpedo californica), was associated with survival of C. rogercresseyi at high azamethiphos concentrations (bioassays and field treatment). The amino acid change was located in the acyl pocket of the active-site gorge of the protein. Conclusions The present study demonstrates the presence of two types of AChE1 genes in C. rogercresseyi. Although enzymatic assays are needed, AChE1a is most probably the main synaptic AChE. The function of AChE1b is unknown, but evidence points to a scavenger role. The AChE1a F/V318 variant is most probably involved in organophosphate resistance, and can be a good marker for resistance monitoring. Electronic supplementary material The online version of this article (10.1186/s13071-018-3151-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Celia Agusti-Ridaura
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Sea Lice Research Centre, Postboks 369 Sentrum, Oslo, NO-0102, Norway.
| | - Michael Dondrup
- Department of Informatics, University of Bergen, Sea Lice Research Centre, Thormøhlensgate 55, N-5008, Bergen, Norway
| | - Tor E Horsberg
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Sea Lice Research Centre, Postboks 369 Sentrum, Oslo, NO-0102, Norway
| | - Jong S Leong
- Biology Department, Centre for Biomedical Research, University of Victoria, Station CSC, PO Box 1700, Victoria, BC, V8W 2Y2, Canada
| | - Ben F Koop
- Biology Department, Centre for Biomedical Research, University of Victoria, Station CSC, PO Box 1700, Victoria, BC, V8W 2Y2, Canada
| | - Sandra Bravo
- Universidad Austral de Chile, Casilla 1327, Puerto Montt, Chile
| | - Julio Mendoza
- Cermaq Chile, Diego Portales 2000, Puerto Montt, Chile
| | - Kiranpreet Kaur
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Sea Lice Research Centre, Postboks 369 Sentrum, Oslo, NO-0102, Norway
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122
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Cantrell DL, Rees EE, Vanderstichel R, Grant J, Filgueira R, Revie CW. The Use of Kernel Density Estimation With a Bio-Physical Model Provides a Method to Quantify Connectivity Among Salmon Farms: Spatial Planning and Management With Epidemiological Relevance. Front Vet Sci 2018; 5:269. [PMID: 30425996 PMCID: PMC6218437 DOI: 10.3389/fvets.2018.00269] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/08/2018] [Indexed: 01/08/2023] Open
Abstract
Connectivity in an aquatic setting is determined by a combination of hydrodynamic circulation and the biology of the organisms driving linkages. These complex processes can be simulated in coupled biological-physical models. The physical model refers to an underlying circulation model defined by spatially-explicit nodes, often incorporating a particle-tracking model. The particles can then be given biological parameters or behaviors (such as maturity and/or survivability rates, diel vertical migrations, avoidance, or seeking behaviors). The output of the bio-physical models can then be used to quantify connectivity among the nodes emitting and/or receiving the particles. Here we propose a method that makes use of kernel density estimation (KDE) on the output of a particle-tracking model, to quantify the infection or infestation pressure (IP) that each node causes on the surrounding area. Because IP is the product of both exposure time and the concentration of infectious agent particles, using KDE (which also combine elements of time and space), more accurately captures IP. This method is especially useful for those interested in infectious agent networks, a situation where IP is a superior measure of connectivity than the probability of particles from each node reaching other nodes. Here we illustrate the method by modeling the connectivity of salmon farms via sea lice larvae in the Broughton Archipelago, British Columbia, Canada. Analysis revealed evidence of two sub-networks of farms connected via a single farm, and evidence that the highest IP from a given emitting farm was often tens of kilometers or more away from that farm. We also classified farms as net emitters, receivers, or balanced, based on their structural role within the network. By better understanding how these salmon farms are connected to each other via their sea lice larvae, we can effectively focus management efforts to minimize the spread of sea lice between farms, advise on future site locations and coordinated treatment efforts, and minimize any impact of farms on juvenile wild salmon. The method has wide applicability for any system where capturing infectious agent networks can provide useful guidance for management or preventative planning decisions.
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Affiliation(s)
- Danielle L Cantrell
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Erin E Rees
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada.,Land and Sea Systems Analysis, Granby, QC, Canada
| | - Raphael Vanderstichel
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Jon Grant
- Department of Oceanography, Dalhousie University, Halifax, NS, Canada
| | - Ramón Filgueira
- Marine Affairs Program, Dalhousie University, Halifax, NS, Canada
| | - Crawford W Revie
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
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123
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Chalmers L, Vera LM, Taylor JF, Adams A, Migaud H. Comparative ploidy response to experimental hydrogen peroxide exposure in Atlantic salmon (Salmo salar). FISH & SHELLFISH IMMUNOLOGY 2018; 81:354-367. [PMID: 30012493 PMCID: PMC6115329 DOI: 10.1016/j.fsi.2018.07.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 06/04/2018] [Accepted: 07/10/2018] [Indexed: 05/05/2023]
Abstract
While research into the growth, survival, nutrition and, more recently, disease susceptibility of triploid Atlantic salmon has expanded, there remains an overall lack of studies assessing the response of triploids to chemical treatments. It is essential that the response of triploids to disease treatments be characterised to validate their suitability for commercial production. This study aimed to investigate and compare the stress and immune responses of triploid and diploid Atlantic salmon following an experimental treatment with hydrogen peroxide (H2O2). A dose response test was first undertaken to determine a suitable test dose for both diploid and triploid Atlantic salmon. Following this, diploids and triploids were exposed to H2O2 (1800 ppm) for 20 min, as per commercial practices, after which blood glucose and lactate, and plasma cortisol and lysozyme were measured, along with the expression of oxidative stress and immune-related genes. In the first 6 h post-exposure to H2O2, comparable mortalities occurred in both diploid and triploid Atlantic salmon. Cortisol, glucose and lactate were not significantly influenced by ploidy suggesting that, physiologically, triploid Atlantic salmon are able to cope with the stress associated with H2O2 exposure as well as their diploid counterparts. Exposure to H2O2 significantly elevated the expression of cat and sod2 in diploid livers and gr, il1β and crp/sap1b in diploid gills, while it significantly decreased the expression of saa5 and crp/sap1a in diploid gills. In triploids, the expression levels of cat, hsp70, sod1, saa5, crp/sap1a and crp/sap1b in liver was significantly higher in fish exposed to H2O2 compared to control fish. The expression of gr, sod1 and il1β in triploid gills was also elevated in response to H2O2 exposure. This study represents the first experimental evidence of the effects of H2O2 exposure on triploid Atlantic salmon and continues to support their application into commercial production.
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Affiliation(s)
- Lynn Chalmers
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK
| | - Luisa M Vera
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK
| | - John F Taylor
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK
| | - Alexandra Adams
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK
| | - Herve Migaud
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
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124
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Cleaner shrimp are a sustainable option to treat parasitic disease in farmed fish. Sci Rep 2018; 8:13959. [PMID: 30228312 PMCID: PMC6143594 DOI: 10.1038/s41598-018-32293-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 08/31/2018] [Indexed: 12/02/2022] Open
Abstract
Chemical use is widespread in aquaculture to treat parasitic diseases in farmed fish. Cleaner fish biocontrols are increasingly used in fish farming as an alternative to medicines. However, cleaner fish are susceptible to some of their clients’ parasites and their supply is largely dependent on wild harvest. In comparison, cleaner shrimp are not susceptible to fish ectoparasites and they can be reliably bred in captivity. The effectiveness of shrimp in reducing parasites on farmed fish remained unexplored until now. We tested four cleaner shrimp species for their ability to reduce three harmful parasites (a monogenean fluke, a ciliate protozoan, and a leech) on a farmed grouper. All shrimp reduced parasites on fish and most reduced the free-living early-life environmental stages – a function not provided by cleaner fish. Cleaner shrimp are sustainable biocontrol candidates against parasites of farmed fish, with the peppermint cleaner shrimp reducing parasites by up to 98%.
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125
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Øvergård AC, Hamre LA, Grotmol S, Nilsen F. Salmon louse rhabdoviruses: Impact on louse development and transcription of selected Atlantic salmon immune genes. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 86:86-95. [PMID: 29747070 DOI: 10.1016/j.dci.2018.04.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 04/27/2018] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
Recently, it has been shown that the salmon louse (Lepeophtheirus salmonis) is commonly infected by one or two vertically transmitted Lepeophtheirus salmonis rhabdoviruses (LsRVs). As shown in the present study, the viruses have limited effect on louse survival, developmental rate and fecundity. Since the LsRVs were confirmed to be present in the louse salivary glands, the salmon cutaneous immune response towards LsRV positive and negative lice was analyzed. In general, L. salmonis increased the expression of IL1β, IL8 and IL4/13A at the attachment site, in addition to the non-specific cytotoxic cell receptor protein 1 (NCCRP-1). Interestingly, LsRV free lice induced a higher skin expression of IL1β, IL8, and NCCRP-1 than the LsRV infected lice. The inflammatory response is important for louse clearance, and the present results suggest that the LsRVs can be beneficial for the louse by dampening inflammation. Further research is, however; needed to ascertain whether this is a direct modulatory effect of secreted virions, or if virus replication is altering the level of louse salivary gland proteins.
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Affiliation(s)
- Aina-Cathrine Øvergård
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
| | - Lars Are Hamre
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
| | - Sindre Grotmol
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
| | - Frank Nilsen
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
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126
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Guarracino M, Qviller L, Lillehaug A. Evaluation of aquaculture management zones as a control measure for salmon lice in Norway. DISEASES OF AQUATIC ORGANISMS 2018; 130:1-9. [PMID: 30154267 DOI: 10.3354/dao03254] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We evaluated the use of coordinated fallowing as a means to control salmon lice Lepeophtheirus salmonis infestation in farmed Atlantic salmon Salmo salar. In discrete management zones, aquaculture operations such as stocking, fallowing, treatments and harvesting are synchronized at all sites in coordinated areas within the zones. The expected benefit of synchronized generations is to reduce the presence of salmon lice larvae after a period of fallowing, as well as to minimize external infestation pressure from surrounding aquaculture sites. A regression analysis was used to evaluate the effectiveness of coordinated fallowing on the progression of external salmon lice infestation pressure and abundance in Atlantic salmon farming sites in 2 areas (zones) in Norway. The overall results show that external infestation pressure was higher inside than outside the management zones, and the external infestation pressure increased with increasing biomass throughout the production cycle. However, within the zones, the external infestation pressure at the beginning of a production cycle was high and in many cases even higher than the general external infestation pressure in the non-coordinated areas. This suggests that external infestation pressure from the neighboring areas has a considerable effect on the fallowed area. Higher numbers of salmon lice were recorded within the zones than outside and, as the production cycle progressed, this phenomenon became more evident. We conclude that the high infestation pressure from salmon lice at the beginning of the grow-out period after fallowing raises severe doubts about the effectiveness of coordinated fallowing practices.
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Affiliation(s)
- Mario Guarracino
- Norwegian Veterinary Institute, PO Box 750 Sentrum, 0106 Oslo, Norway
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127
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Robledo D, Gutiérrez AP, Barría A, Yáñez JM, Houston RD. Gene Expression Response to Sea Lice in Atlantic Salmon Skin: RNA Sequencing Comparison Between Resistant and Susceptible Animals. Front Genet 2018; 9:287. [PMID: 30123239 PMCID: PMC6086009 DOI: 10.3389/fgene.2018.00287] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/11/2018] [Indexed: 12/27/2022] Open
Abstract
Sea lice are parasitic copepods that cause large economic losses to salmon aquaculture worldwide. Frequent chemotherapeutic treatments are typically required to control this parasite, and alternative measures such as breeding for improved host resistance are desirable. Insight into the host-parasite interaction and mechanisms of host resistance can lead to improvements in selective breeding, and potentially novel treatment targets. In this study, RNA sequencing was used to study the skin transcriptome of Atlantic salmon (Salmo salar) parasitized with sea lice (Caligus rogercresseyi). The overall aims were to compare the transcriptomic profile of skin at louse attachment sites and "healthy" skin, and to assess differences in gene expression response between animals with varying levels of resistance to the parasite. Atlantic salmon pre-smolts were challenged with C. rogercresseyi, growth and lice count measurements were taken for each fish. 21 animals were selected and RNA-Seq was performed on skin from a louse attachment site, and skin distal to attachment sites for each animal. These animals were classified into family-balanced groups according to the traits of resistance (high vs. low lice count), and growth during infestation. Overall comparison of skin from louse attachment sites vs. healthy skin showed that 4,355 genes were differentially expressed, indicating local up-regulation of several immune pathways and activation of tissue repair mechanisms. Comparison between resistant and susceptible animals highlighted expression differences in several immune response and pattern recognition genes, and also myogenic and iron availability factors. Components of the pathways involved in differential response to sea lice may be targets for studies aimed at improved or novel treatment strategies, or to prioritize candidate functional polymorphisms to enhance genomic selection for host resistance in commercial salmon breeding programs.
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Affiliation(s)
- Diego Robledo
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh, United Kingdom
| | - Alejandro P. Gutiérrez
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh, United Kingdom
| | - Agustín Barría
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
| | - José M. Yáñez
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
- Aquainnovo S.A., Puerto Montt, Chile
| | - Ross D. Houston
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh, United Kingdom
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128
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Poley JD, Braden LM, Messmer AM, Igboeli OO, Whyte SK, Macdonald A, Rodriguez J, Gameiro M, Rufener L, Bouvier J, Wadowska DW, Koop BF, Hosking BC, Fast MD. High level efficacy of lufenuron against sea lice (Lepeophtheirus salmonis) linked to rapid impact on moulting processes. Int J Parasitol Drugs Drug Resist 2018; 8:174-188. [PMID: 29627513 PMCID: PMC6039351 DOI: 10.1016/j.ijpddr.2018.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 02/26/2018] [Accepted: 02/28/2018] [Indexed: 11/29/2022]
Abstract
Drug resistance in the salmon louse Lepeophtheirus salmonis is a global issue for Atlantic salmon aquaculture. Multiple resistance has been described across most available compound classes with the exception of the benzoylureas. To target this gap in effective management of L. salmonis and other species of sea lice (e.g. Caligus spp.), Elanco Animal Health is developing an in-feed treatment containing lufenuron (a benzoylurea) to be administered prior to seawater transfer of salmon smolts and to provide long-term protection of salmon against sea lice infestations. Benzoylureas disrupt chitin synthesis, formation, and deposition during all moulting events. However, the mechanism(s) of action are not yet fully understood and most research completed to date has focused on insects. We exposed the first parasitic stage of L. salmonis to 700 ppb lufenuron for three hours and observed over 90% reduction in survival to the chalimus II life stage on the host, as compared to vehicle controls. This agrees with a follow up in vivo administration study on the host, which showed >95% reduction by the chalimus I stage. Transcriptomic responses of salmon lice exposed to lufenuron included genes related to moulting, epithelial differentiation, solute transport, and general developmental processes. Global metabolite profiles also suggest that membrane stability and fluidity is impacted in treated lice. These molecular signals are likely the underpinnings of an abnormal moulting process and cuticle formation observed ultrastructurally using transmission electron microscopy. Treated nauplii-staged lice exhibited multiple abnormalities in the integument, suggesting that the coordinated assembly of the epi- and procuticle is impaired. In all cases, treatment with lufenuron had rapid impacts on L. salmonis development. We describe multiple experiments to characterize the efficacy of lufenuron on eggs, larvae, and parasitic stages of L. salmonis, and provide the most comprehensive assessment of the physiological responses of a marine arthropod to a benzoylurea chemical.
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Affiliation(s)
- Jordan D Poley
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Laura M Braden
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Amber M Messmer
- Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria BC, V8W 3N5, Canada.
| | - Okechukwu O Igboeli
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Shona K Whyte
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Alicia Macdonald
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Jose Rodriguez
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Marta Gameiro
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Lucien Rufener
- Elanco Centre de Recherche Santé Animale SA, CH-1566 St.-Aubin, Switzerland; INVENesis LLC, Chemin de Belleroche 14, 2000 Neuchâtel, Switzerland.
| | - Jacques Bouvier
- Elanco Centre de Recherche Santé Animale SA, CH-1566 St.-Aubin, Switzerland; INVENesis LLC, Chemin de Belleroche 14, 2000 Neuchâtel, Switzerland.
| | - Dorota W Wadowska
- Electron Microscopy Laboratory, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PEI, C1A 4P3, Canada.
| | - Ben F Koop
- Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria BC, V8W 3N5, Canada.
| | - Barry C Hosking
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Mark D Fast
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
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129
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Marín SL, Mancilla J, Hausdorf MA, Bouchard D, Tudor MS, Kane F. Sensitivity assessment of sea lice to chemotherapeutants: Current bioassays and best practices. JOURNAL OF FISH DISEASES 2018; 41:995-1003. [PMID: 29251354 DOI: 10.1111/jfd.12768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/27/2017] [Accepted: 11/15/2017] [Indexed: 06/07/2023]
Abstract
Traditional bioassays are still necessary to test sensitivity of sea lice species to chemotherapeutants, but the methodology applied by the different scientists has varied over time in respect to that proposed in "Sea lice resistance to chemotherapeutants: A handbook in resistance management" (2006). These divergences motivated the organization of a workshop during the Sea Lice 2016 conference "Standardization of traditional bioassay process by sharing best practices." There was an agreement by the attendants to update the handbook. The objective of this article is to provide a baseline analysis of the methodology for traditional bioassays and to identify procedures that need to be addressed to standardize the protocol. The methodology was divided into the following steps: bioassay design; material and equipment; sea lice collection, transportation and laboratory reception; preparation of dilution; parasite exposure; response evaluation; data analysis; and reporting. Information from the presentations of the workshop, and also from other studies, allowed for the identification of procedures inside a given step that need to be standardized as they were reported to be performed differently by the different working groups. Bioassay design and response evaluation were the targeted steps where more procedures need to be analysed and agreed upon.
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Affiliation(s)
- S L Marín
- Institute of Aquaculture, Universidad Austral de Chile, Puerto Montt, Chile
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Puerto Montt, Chile
| | - J Mancilla
- PhD Aquaculture Sciences, Universidad Austral de Chile, Puerto Montt, Chile
| | | | - D Bouchard
- University of Maine Animal Health Laboratory, University of Maine, Orono, ME, USA
| | - M S Tudor
- University of Maine Animal Health Laboratory, University of Maine, Orono, ME, USA
| | - F Kane
- Aquaculture Section, Marine Institute, Galway, Ireland
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130
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Salama NKG, Dale AC, Ivanov VV, Cook PF, Pert CC, Collins CM, Rabe B. Using biological-physical modelling for informing sea lice dispersal in Loch Linnhe, Scotland. JOURNAL OF FISH DISEASES 2018; 41:901-919. [PMID: 28782801 DOI: 10.1111/jfd.12693] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 05/31/2017] [Accepted: 06/29/2017] [Indexed: 06/07/2023]
Abstract
Sea lice are a constraint on the sustainable growth of Scottish marine salmonid aquaculture. As part of an integrated pest management approach, farms coordinate procedures within spatial units. We present observations of copepodids being at relatively greater density than nauplii in upper waters, which informs the development of surface layer sea lice transmission modelling of Loch Linnhe, Scotland, for informing farm parasite management. A hydrodynamic model is coupled with a biological particle-tracking model, with characteristics of plankton sea lice. Simulations are undertaken for May and October 2011-2013, forced by local wind data collected for those periods. Particles are continually released from positions representing farm locations, weighted by relative farm counts, over a 2-week period and tracked for a further 5 days. A comparison is made between modelled relative concentrations against physical and biological surveys to provide confidence in model outputs. Connectivity between farm locations is determined in order to propose potential coordination areas. Generally, connectivity depends on flow patterns in the loch and decreases with increased farm separation. The connectivity indices are used to estimate the origins of the sea lice population composition at each site, which may influence medicinal regimens to avoid loss of efficacy.
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Affiliation(s)
- N K G Salama
- Marine Scotland Science, Marine Laboratory, Aberdeen, UK
| | - A C Dale
- Scottish Marine Institute, The Scottish Association for Marine Science, Oban, UK
| | - V V Ivanov
- Arctic and Antarctic Research Institute, St. Petersburg, Russia
| | - P F Cook
- Marine Scotland Science, Marine Laboratory, Aberdeen, UK
| | - C C Pert
- Marine Scotland Science, Marine Laboratory, Aberdeen, UK
| | - C M Collins
- Marine Scotland Science, Marine Laboratory, Aberdeen, UK
| | - B Rabe
- Marine Scotland Science, Marine Laboratory, Aberdeen, UK
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131
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Eichner C, Dondrup M, Nilsen F. RNA sequencing reveals distinct gene expression patterns during the development of parasitic larval stages of the salmon louse (Lepeophtheirus salmonis). JOURNAL OF FISH DISEASES 2018; 41:1005-1029. [PMID: 29368347 DOI: 10.1111/jfd.12770] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 11/08/2017] [Accepted: 11/10/2017] [Indexed: 06/07/2023]
Abstract
The salmon louse (Lepeophtheirus salmonis), an ectoparasitic copepod on salmonids, has become a major threat for the aquaculture industry. In search for new drugs and vaccines, transcriptome analysis is increasingly used to find differently regulated genes and pathways in response to treatment. However, the underlying gene expression changes going along with developmental processes could confound such analyses. The life cycle of L. salmonis consists of eight stages divided by moults. The developmental rate of salmon lice on the host is not uniform. Individual- and sex-related differences are found leading to individuals of unlike developmental status at same sampling time point after infection. In this study, we analyse L. salmonis from a time series by RNA sequencing applying a method of separating individuals of different instar age independent of sampling time point. Lice of four stages divided into up to four age groups within the stage were analysed in triplicate (total of 66 samples). Gene expression analysis shows that the method for sorting individuals was successful. Many genes show cyclic expression patterns over the moulting cycles. Overall gene expression differs more between lice of different age within the same stage than between lice of different stage but same instar age.
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Affiliation(s)
- C Eichner
- Sea Lice Research Centre, Department of Molecular Biology, University of Bergen, Bergen, Norway
| | - M Dondrup
- Sea Lice Research Centre, Department of Informatics, University of Bergen, Bergen, Norway
| | - F Nilsen
- Sea Lice Research Centre, Department of Biology, University of Bergen, Bergen, Norway
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132
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Fields DM, Skiftesvik AB, Browman HI. Behavioural responses of infective-stage copepodids of the salmon louse (Lepeophtheirus salmonis, Copepoda:Caligidae) to host-related sensory cues. JOURNAL OF FISH DISEASES 2018; 41:875-884. [PMID: 28921570 DOI: 10.1111/jfd.12690] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/23/2017] [Accepted: 06/26/2017] [Indexed: 05/04/2023]
Abstract
The salmon louse (Lepeophtheirus salmonis [Krøyer]) is an ectoparasitic copepod that causes disease in farmed Atlantic salmon (Salmo salar) and may play a role in the decline of some wild salmonid populations. Controlling lice infestations is a major cost for the salmon industry; this has stimulated the pursuit of alternative approaches to controlling them. One such approach involves determining, and then disrupting, the sensory cues used by the parasite to find its host. In this context, we examined the behavioural responses of lice copepodids to light flicker-simulating light reflecting from the sides of the salmon host and/or the shadows cast by fish passing overhead-and water-soluble chemicals released from the skin of the salmon. From these observations, we estimate that visual cues such as those presented here would operate at relatively long range (metres to tens of metres). A diffuse host-related olfactory cue stimulated swimming, however, it remains unclear whether olfactory cues provide directional information. The observations presented herein could be used to disrupt the link between the parasite and host fish, using a large number of traps deployed at a distance from a salmon farm, for example, thereby reducing sea lice infestation pressure.
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Affiliation(s)
- D M Fields
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, USA
| | - A B Skiftesvik
- Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - H I Browman
- Institute of Marine Research, Austevoll Research Station, Storebø, Norway
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133
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Jackson D, Moberg O, Stenevik Djupevåg EM, Kane F, Hareide H. The drivers of sea lice management policies and how best to integrate them into a risk management strategy: An ecosystem approach to sea lice management. JOURNAL OF FISH DISEASES 2018; 41:927-933. [PMID: 29027681 DOI: 10.1111/jfd.12705] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/20/2017] [Accepted: 07/23/2017] [Indexed: 06/07/2023]
Abstract
The control of sea lice infestations on cultivated Atlantic salmon is a major issue in many regions of the world. The numerous drivers which shape the priorities and objectives of the control strategies vary for different regions/jurisdictions. These range from the animal welfare and economic priorities of the producers, to the mitigation of any potential impacts on wild stocks. Veterinary ethics, environmental impacts of therapeutants, and impacts for organic certification of the produce are, amongst others, additional sets of factors which should be considered. Current best practice in both EU and international environmental law advocates a holistic ecosystem approach to assessment of impacts and risks. The issues of biosecurity and ethics, including the impacts on the stocks of species used as cleaner fish, are areas for inclusion in such a holistic ecosystem assessment. The Drivers, Pressures, State, Impacts, Responses (DPSIR) process is examined as a decision-making framework and potential applications to sea lice management are outlined. It is argued that this is required to underpin any integrated sea lice management (ISLM) strategy to balance pressures and outcomes and ensure a holistic approach to managing the issue of sea lice infestations on farmed stock on a medium to long-term basis.
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Affiliation(s)
| | - O Moberg
- Fisheries Directorate, Oslo, Norway
| | | | - F Kane
- Marine Institute, Galway, Ireland
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134
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Deltamethrin resistance in the salmon louse, Lepeophtheirus salmonis (Krøyer): Maternal inheritance and reduced apoptosis. Sci Rep 2018; 8:8450. [PMID: 29855496 PMCID: PMC5981211 DOI: 10.1038/s41598-018-26420-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 05/08/2018] [Indexed: 01/15/2023] Open
Abstract
Resistance towards deltamethrin (DMT) in the crustacean ectoparasite Lepeophtheirus salmonis (Caligidae) is a problem on fish farms lining the North Atlantic Ocean. Two Norwegian strains with different susceptibility towards DMT were crossed in the parental generation (P0), females from a sensitive strain were crossed with males from a resistant strain and vice versa. Individual susceptibility towards DMT was assessed in the second filial generation (F2). DMT resistance was only found in F2 descendants when the P0 females were from the resistant strain, pointing to maternal inheritance. Since maternal inheritance might be linked to the mitochondrial (mt) genome, the nucleotide sequences and the gene expressions of mt-genes were analysed. Twenty non-synonymous single nucleotide polymorphisms (SNPs) were identified in mt-transcripts from resistant F2 parasites, including SNPs in two cytochrome C oxidase subunits (COX1 and COX3) and two subunits of the NADH dehydrogenase complex (ND1 and ND5) previously linked to DMT resistance in the salmon louse. Differential expression analysis between the sensitive and resistant strain revealed strain effect in seven out of twelve mt-genes. The current study also show that DNA fragmentation (indicating apoptosis) was affected by DMT exposure in skeletal muscle tissue and that resistant parasites undergo less apoptosis than sensitive parasites.
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135
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Johannesen A, Joensen NE, Magnussen E. Shelters can negatively affect growth and welfare in lumpfish if feed is delivered continuously. PeerJ 2018; 6:e4837. [PMID: 29844984 PMCID: PMC5971831 DOI: 10.7717/peerj.4837] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/04/2018] [Indexed: 11/20/2022] Open
Abstract
Due to the socioeconomic importance of salmon farming in the North Atlantic and the economic impact of sea lice in this industry, there is high demand for novel pest control methods. One such method is the use of cleaner fish to remove the lice from the salmon. A cleaner fish that has recently gained in popularity due to its ability to work in cold water, is the lumpfish (Cyclopterus lumpus). This fish varies in efficiency, but when mortality is low and cleaning optimal, the fish are successful in keeping parasite burdens low. However, there is some concern for the welfare of lumpfish in the industry, because mortality is often high. This is sometimes attributed to inadequate feeding and shelter. Here we compare growth, body condition, and fin health of fish reared for four weeks in a crossed treatment design crossing shelter availability (shelter vs none) and feed delivery method (manual meal time feeds and continuous automated feeding). In terms of weight gain, shelter availability interacted with feeding method, with fish that had access to shelters and were fed using automated feeders gaining less weight than other fish. Fin health was not affected, but body condition was lowered both by access to shelter and being fed continuously. The results indicate a need to carefully consider how feeding method and shelter use is combined, both in cages and during rearing on land.
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Affiliation(s)
- Asa Johannesen
- Nesvik Marine Centre, Fiskaaling, Hvalvik, Faroe Islands
| | - Nakita E Joensen
- Department of Science and Technology, University of the Faroe Islands, Tórshavn, Faroe Islands
| | - Eyðfinn Magnussen
- Department of Science and Technology, University of the Faroe Islands, Tórshavn, Faroe Islands
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136
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Borchel A, Nilsen F. A novel gene-family involved in spermatophore generation in the economically important salmon louse Lepeophtheirus salmonis. Mol Reprod Dev 2018; 85:478-489. [PMID: 29633415 DOI: 10.1002/mrd.22984] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 11/06/2022]
Abstract
The salmon louse (Lepeophtheirus salmonis) is an important parasite of Atlantic salmon (Salmo salar). It is widely spread in aquaculture facilities and leads to economic losses every year. As it has developed resistances against many common treatments, new control methods must be established. Here we characterize a novel gene family of the salmon louse, consisting of two genes, which has not been described in other species before. We analyzed temporal expression patterns of both genes, the localization of mRNA and protein. An RNAi mediated gene knockdown lead to information about the function of the protein. Overall, these two genes are expressed only in sperm ducts of male sea lice. The mucin-like proteins can additionally be found in the wall of spermatophores, which are responsible for sperm transfer to females. Knockdown showed that both genes are essential for successful fertilization of females. Overall, all results indicate that the two analyzed genes are necessary for reproduction in sea lice as they are essential for the formation of a wall surrounding the spermatophores, which is needed for fertilization. Therefore, we name them Mucin-like spermatophore wall protein 1 & 2 (MLSWP1 & MLSWP2). Analysis of sequence data from other copepod species suggests that MLSWPs are present in many copepod species and may also play a similar role in reproduction in those species.
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Affiliation(s)
- Andreas Borchel
- SLRC-SeaLiceResearch Centre, Department of Biology, University of Bergen, Bergen, Norway
| | - Frank Nilsen
- SLRC-SeaLiceResearch Centre, Department of Biology, University of Bergen, Bergen, Norway
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137
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Sandlund L, Kongshaug H, Nilsen F, Dalvin S. Molecular characterization and functional analysis of components of the TOR pathway of the salmon louse, Lepeophtheirus salmonis (Krøyer, 1838). Exp Parasitol 2018; 188:83-92. [PMID: 29625096 DOI: 10.1016/j.exppara.2018.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/16/2018] [Accepted: 04/02/2018] [Indexed: 11/27/2022]
Abstract
The salmon louse Lepeophtheirus salmonis (Copepods, Caligida) is a marine ectoparasite infecting salmonid fishes in the northern hemisphere. At present, salmon lice infections are the most severe disease problem in the salmon farming industry causing significant economic losses. Due to development of resistance towards available chemotherapeutants, it is clear that new chemotherapeutants or non-chemical control methods are essential to manage the parasite in the future. The TOR signaling pathway is present in all metazoans and is a major regulator of cellular activity according to nutrient availability. In this study, we identified the TOR pathway genes in salmon louse; LsTSC1, LsTSC2, LsRheb, LsTOR, LsRaptor and LsRictor. RNA interference mediated gene silencing was performed to elucidate the functional role of each member of the pathway. Our results show that interference of the TOR signaling pathway either directly or indirectly inhibits many biological processes including egg maturation. In addition, the effect of gene knock-down results in more comprehensive physiological defects when targeting TORC1 and the upstream regulator Rheb. This is the first report on the TOR pathway in the salmon louse and that our research contributes to the basic knowledge of the parasite that could lead to development of novel treatment methods.
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Affiliation(s)
- Liv Sandlund
- SLRC-Sea Lice Research Center, Institute of Marine Research, 5817 Bergen, Norway
| | - Heidi Kongshaug
- SLRC-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Frank Nilsen
- SLRC-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Sussie Dalvin
- SLRC-Sea Lice Research Center, Institute of Marine Research, 5817 Bergen, Norway.
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138
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Overton K, Samsing F, Oppedal F, Stien LH, Dempster T. Lowering treatment temperature reduces salmon mortality: a new way to treat with hydrogen peroxide in aquaculture. PEST MANAGEMENT SCIENCE 2018; 74:535-540. [PMID: 28980393 DOI: 10.1002/ps.4751] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 09/20/2017] [Accepted: 09/27/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Hydrogen peroxide (H2 O2 ) baths are widely used to reduce numbers of salmon lice on farmed Atlantic salmon. Fish mortalities often occur after baths, with warmer temperatures increasing lethality. We tested whether mortality could be reduced and lice removal efficacy maintained by lowering bath temperatures relative to ambient temperatures. Post-smolt salmon infected with lice were held at 10, 13 or 16 °C, and treated with 1.5 g/L H2 O2 for 20 min at equal or lower bath temperatures of 7, 10 or 13 °C. RESULTS Salmon mortality decreased as ambient and bath temperatures decreased. No mortality occurred when fish at 13 °C were treated at 7 °C. For ambient temperatures of 16 °C, the number of lice remaining was reduced by four-fold when treated at 7 °C compared with 13 °C. All treatments in which mortality was zero had similar efficacies regardless of bath temperature. CONCLUSION We took salmon from warmer to colder temperatures to determine the optimum bathing temperature to prevent mortality. A temperature of 7 °C was optimal when treating with 1.5 g/L of H2 O2 , as mortality was zero and pre-adult lice removal was unchanged. By manipulating temperature, we developed a new method of H2 O2 bathing that reduces mortality. When ambient temperatures are >10 °C, we recommend that the industry decrease H2 O2 bath temperatures. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Kathy Overton
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), University of Melbourne, Parkville, Australia
| | - Francisca Samsing
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), University of Melbourne, Parkville, Australia
| | | | | | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), University of Melbourne, Parkville, Australia
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139
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Chance RJ, Allcock Z, Secombes CJ, Collet B, Collins C. Effect of repeated exposure to AQUI-S ® on the viability and growth of Neoparamoeba perurans. JOURNAL OF FISH DISEASES 2018; 41:291-298. [PMID: 28944485 PMCID: PMC5813168 DOI: 10.1111/jfd.12712] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 06/07/2023]
Abstract
There have been recent efforts amongst immunologists to develop approaches for following individual fish during challenges with viral and bacterial pathogens. This study contributes to assessing the feasibility of using such approaches to study amoebic gill disease (AGD). Neoparamoeba perurans, agent of AGD, has been responsible for widespread economic and fish loss in salmonid aquaculture. With the emergence of AGD in Europe, research into infection dynamics and host response has increased. This study investigated the effect of repeat exposure to anaesthesia, a necessary requirement when following disease progression in individual fish, on N. perurans. In vitro cultures of N. perurans were exposed every 4 days over a 28-day period to AQUI-S® (isoeugenol), a popular anaesthetic choice for AGD challenges, at a concentration and duration required to sedate post-smolt salmonids. Population growth was measured by sequential counts of amoeba over the period, while viability of non-attached amoeba in the culture was assessed with a vital stain. AQUI-S® was found to be a suitable choice for in vivo ectoparasitic challenges with N. perurans during which repetitive anaesthesia is required for analysis of disease progression.
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Affiliation(s)
- R J Chance
- Scottish Fish Immunology Research CentreUniversity of AberdeenAberdeenScotland
- Marine Laboratory, Marine ScotlandAberdeenScotland
| | - Z Allcock
- Marine Laboratory, Marine ScotlandAberdeenScotland
| | - C J Secombes
- Scottish Fish Immunology Research CentreUniversity of AberdeenAberdeenScotland
| | - B Collet
- Marine Laboratory, Marine ScotlandAberdeenScotland
| | - C Collins
- Marine Laboratory, Marine ScotlandAberdeenScotland
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140
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Gene silencing reveals multiple functions of Na +/K +-ATPase in the salmon louse (Lepeophtheirus salmonis). Exp Parasitol 2018; 185:79-91. [PMID: 29339143 DOI: 10.1016/j.exppara.2018.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 10/23/2017] [Accepted: 01/03/2018] [Indexed: 11/20/2022]
Abstract
Na+/K+-ATPase has a key function in a variety of physiological processes including membrane excitability, osmoregulation, regulation of cell volume, and transport of nutrients. While knowledge about Na+/K+-ATPase function in osmoregulation in crustaceans is extensive, the role of this enzyme in other physiological and developmental processes is scarce. Here, we report characterization, transcriptional distribution and likely functions of the newly identified L. salmonis Na+/K+-ATPase (LsalNa+/K+-ATPase) α subunit in various developmental stages. The complete mRNA sequence was identified, with 3003 bp open reading frame encoding a putative protein of 1001 amino acids. Putative protein sequence of LsalNa+/K+-ATPase revealed all typical features of Na+/K+-ATPase and demonstrated high sequence identity to other invertebrate and vertebrate species. Quantitative RT-PCR analysis revealed higher LsalNa+/K+-ATPase transcript level in free-living stages in comparison to parasitic stages. In situ hybridization analysis of copepodids and adult lice revealed LsalNa+/K+-ATPase transcript localization in a wide variety of tissues such as nervous system, intestine, reproductive system, and subcuticular and glandular tissue. RNAi mediated knock-down of LsalNa+/K+-ATPase caused locomotion impairment, and affected reproduction and feeding. Morphological analysis of dsRNA treated animals revealed muscle degeneration in larval stages, severe changes in the oocyte formation and maturation in females and abnormalities in tegmental glands. Thus, the study represents an important foundation for further functional investigation and identification of physiological pathways in which Na+/K+-ATPase is directly or indirectly involved.
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141
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Borchel A, Komisarczuk AZ, Rebl A, Goldammer T, Nilsen F. Systematic identification and characterization of stress-inducible heat shock proteins (HSPs) in the salmon louse (Lepeophtheirus salmonis). Cell Stress Chaperones 2018; 23:127-139. [PMID: 28695332 PMCID: PMC5741587 DOI: 10.1007/s12192-017-0830-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 06/21/2017] [Accepted: 06/23/2017] [Indexed: 02/06/2023] Open
Abstract
Salmon lice (Lepeophtheirus salmonis) are parasitic copepods, living mainly on Atlantic salmon and leading to large economical losses in aquaculture every year. Due to the emergence of resistances to several drugs, alternative treatments are developed, including treatment with hydrogen peroxide, freshwater or thermal treatment. The present study gives a first overview of the thermotolerance and stress response of salmon lice. Sea lice nauplii acclimated to 10 °C can survive heat shocks up to 30 °C and are capable of hardening by a sublethal heat shock. We searched in the genome for heat shock protein (HSP) encoding genes and tested their inducibility after heat shock, changes in salinity and treatment with hydrogen peroxide, employing microfluidic qPCRs. We assessed 38 candidate genes, belonging to the small HSP, HSP40, HSP70 and HSP90 families. Nine of these genes showed strong induction after a non-lethal heat shock. In contrast, only three and two of these genes were induced after changes in salinity and incubation in hydrogen peroxide, respectively. This work provides the basis for further work on the stress response on the economically important parasite L. salmonis.
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Affiliation(s)
- Andreas Borchel
- SLRC-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008, Bergen, Norway.
| | - Anna Z Komisarczuk
- SLRC-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008, Bergen, Norway
| | - Alexander Rebl
- Leibniz Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany
| | - Tom Goldammer
- Leibniz Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany
| | - Frank Nilsen
- SLRC-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008, Bergen, Norway
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142
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Where Is the Breakthrough Innovation for Parasite Control? Trends Parasitol 2017; 34:99-101. [PMID: 29191558 DOI: 10.1016/j.pt.2017.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 11/10/2017] [Accepted: 11/13/2017] [Indexed: 11/21/2022]
Abstract
The need to improve parasite control to overcome drug-resistant parasite populations, and to improve compliance by more convenient drug application methods, is evident. While a number of incremental stepwise improvements are visible, the big disruptive innovation, an iPhone-equivalent breakthrough, has been hard to find. Why?
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143
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Øvergård AC, Hamre LA, Kongshaug H, Nilsen F. RNAi-mediated treatment of two vertically transmitted rhabdovirus infecting the salmon louse (Lepeophtheirus salmonis). Sci Rep 2017; 7:14030. [PMID: 29070796 PMCID: PMC5656668 DOI: 10.1038/s41598-017-14282-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/06/2017] [Indexed: 12/21/2022] Open
Abstract
Rhabdoviruses are a family of enveloped negative-sense single-stranded RNA viruses infecting a variety of hosts. Recently, two vertically transmitted salmon louse (Lepeophtheirus salmonis) rhabdoviruses (LsRV) have been identified. The prevalence of these viruses was measured along the Norwegian coast and found to be close to 100%, and with the present lack of suitable cell lines to propagate these viruses, it is challenging to obtain material to study their host impact and infection routes. Thus, virus free lice strains were established from virus infected lice carrying one or both LsRVs by treating them with N protein dsRNA twice during development. The viral replication of the N protein was specifically down-regulated following introduction of virus-specific dsRNA, and virus-free lice strains were maintained for several generations. A preliminary study on infection routes suggested that the LsRV-No9 is maternally transmitted, and that the virus transmits from males to females horizontally. The ability to produce virus free strains allows for further studies on transmission modes and how these viruses influences on the L.salmonis interaction with its salmonid host. Moreover, this study provides a general fundament for future studies on how vertically transmitted rhabdoviruses influence the biology of their arthropod hosts.
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Affiliation(s)
- Aina-Cathrine Øvergård
- SLCR-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, Pb. 7803, NO-5020, Bergen, Norway.
| | - Lars Are Hamre
- SLCR-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, Pb. 7803, NO-5020, Bergen, Norway
| | - Heidi Kongshaug
- SLCR-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, Pb. 7803, NO-5020, Bergen, Norway
| | - Frank Nilsen
- SLCR-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, Pb. 7803, NO-5020, Bergen, Norway
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144
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McEwan GF, Groner ML, Burnett DL, Fast MD, Revie CW. Managing aquatic parasites for reduced drug resistance: lessons from the land. J R Soc Interface 2017; 13:rsif.2016.0830. [PMID: 28003529 DOI: 10.1098/rsif.2016.0830] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 11/28/2016] [Indexed: 11/12/2022] Open
Abstract
Atlantic salmon farming is one of the largest aquaculture industries in the world. A major problem in salmon farms is the sea louse ectoparasite Lepeophtheirus salmonis, which can cause stress, secondary infection and sometimes mortality in the salmon host. Sea lice have substantial impacts on farm economics and potentially nearby wild salmonid populations. The most common method of controlling sea louse infestations is application of chemicals. However, most farming regions worldwide have observed resistance to the small set of treatment chemicals that are available. Despite this, there has been little investigation of treatment strategies for managing resistance in aquaculture. In this article, we compare four archetypical treatment strategies inspired by agriculture, where the topic has a rich history of study, and add a fifth strategy common in aquaculture. We use an agent-based model (ABM) to simulate these strategies and their varying applications of chemicals over time and space. We analyse the ABM output to compare how the strategies perform in controlling louse abundance, number of treatments required and levels of resistance in the sea louse population. Our results indicated that among the approaches considered applying chemicals in combination was the most effective over the long term.
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Affiliation(s)
- Gregor F McEwan
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Maya L Groner
- Departments of Fisheries Management and Aquatic Health Sciences, Virginia Institute of Marine Science, 1375 Greate Road, Gloucester Point, VA 23062-1346, USA
| | - Danielle L Burnett
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Mark D Fast
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Crawford W Revie
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
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145
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Gebauer P, Paschke K, Vera C, Toro JE, Pardo M, Urbina M. Lethal and sub-lethal effects of commonly used anti-sea lice formulations on non-target crab Metacarcinus edwardsii larvae. CHEMOSPHERE 2017; 185:1019-1029. [PMID: 28763937 DOI: 10.1016/j.chemosphere.2017.07.108] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 07/10/2017] [Accepted: 07/19/2017] [Indexed: 05/28/2023]
Abstract
The pesticides used by the salmon industry to treat sea lice, are applied in situ via a bath solution and are subsequently discharged into the surrounding medium. The effects of cypermethrin, deltamethrin, azamethiphos and hydrogen peroxide were assessed on the performance of Metacarcinus edwardsii larvae, an important crab for Chilean fishery. All larvae were dead or dying after 30 min of exposure to cypermethrin and after 40 min to deltamethrin at concentrations 100 and 20 times lower (0.15 and 0.1 μg L-1, respectively) than the concentrations and exposure times recommended by the manufacturers (CRM) to treat sea lice. Azamethiphos affected all larvae at a concentration 10 times lower than CRM. Hydrogen peroxide had the lowest detrimental effects, but at the CRM, 100% of the larvae were affected. Sub-lethal effects, i.e prolonged developmental time, were observed at concentrations lower than CRM. Repeated exposure to azamethiphos (0.0625-0.5 μg L-1) and hydrogen peroxide (188-1500 mg L-1) had effects on survival. In conclusion, the pesticides used against parasitic copepod tested here, negatively affect non-target crustacean larvae. Due to the product's characteristics, the lethal effects of the pyrethroids probably are restricted to the time and area of application, while the action of azamethiphos may extend to a wider area. Current data are insufficient to accurately dimension the effects of these compounds in the field. More research is required to evaluate the consequences of prolonged developmental times and/or reduction in appendage mobility, so as the effects of these compounds on the pelagic and benthic communities.
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Affiliation(s)
- Paulina Gebauer
- Centro i∼mar, Universidad de Los Lagos, Casilla 557 Puerto Montt, Chile.
| | - Kurt Paschke
- Instituto de Acuicultura, Universidad Austral de Chile, Casilla 1327, Puerto Montt, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Chile
| | - Claudia Vera
- Instituto de Acuicultura, Universidad Austral de Chile, Casilla 1327, Puerto Montt, Chile
| | - Jorge E Toro
- Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Miguel Pardo
- Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Chile
| | - Mauricio Urbina
- Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Chile
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146
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Martin SAM, Król E. Nutrigenomics and immune function in fish: new insights from omics technologies. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 75:86-98. [PMID: 28254621 PMCID: PMC5495911 DOI: 10.1016/j.dci.2017.02.024] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 02/24/2017] [Accepted: 02/26/2017] [Indexed: 05/29/2023]
Abstract
The interplay between nutrition and immune system is well recognised, however the true integration of research between nutrition, animal energy status and immune function is still far from clear. In fish nutrition, especially for species maintained in aquaculture, formulated feeds are significantly different from the natural diet with recent changes in nutrient sources, especially with protein and oil sources now being predominated by terrestrial derived ingredients. Additionally, many feeds are now incorporated to health management and termed functional feeds, which are believed to improve fish health, reduce disease outbreaks and/or improve post-infection recovery. Using new omics technologies, including transcriptomics (microarray and RNA-seq) and proteomics, the impacts of nutrition on the immune system is becoming clearer. By using molecular pathway enrichment analysis, modules of genes can indicate how both local (intestinal) and systemic immune function are being altered. Although great progress has been made to define the changes in host immune function, understanding the interplay between fish nutrition, intestinal microbiome and immune system is only just beginning to emerge.
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Affiliation(s)
- Samuel A M Martin
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK.
| | - Elżbieta Król
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
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147
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The mechanism (Phe362Tyr mutation) behind resistance in Lepeophtheirus salmonis pre-dates organophosphate use in salmon farming. Sci Rep 2017; 7:12349. [PMID: 28955050 PMCID: PMC5617835 DOI: 10.1038/s41598-017-12384-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 09/07/2017] [Indexed: 11/29/2022] Open
Abstract
The salmon louse is an ectoparasitic copepod of salmonids in the marine environment, and represents a global challenge to salmon aquaculture. A major issue is the reliance of the industry on a limited number of chemicals to delouse salmonids on farms, and the high levels of resistance that lice have developed to all of these agents. However, for most of these chemicals, resistance and dispersal mechanisms are unknown. We recently demonstrated that the Phe362Tyr mutation is the primary cause of organophosphate resistance in lice collected on Norwegian farms. In the present study, we genotyped >2000 lice collected throughout the entire North Atlantic in the period 1998–2016, using Phe362Tyr and nine tightly linked SNPs. Our results showed that the Phe362Tyr mutation is strongly linked to lice survival following chemical treatment on farms located throughout the North Atlantic, demonstrating for the first time, that this mutation represents the primary mechanism for organophosphate resistance in salmon lice across the North Atlantic. Additionally, we observed multiple and diverse high frequency haplotypes linked with the allele conveying resistance to organophosphate. We, therefore, conclude that Phe362Tyr is not a de novo mutation, but probably existed in salmon lice before the introduction of organophosphates in commercial aquaculture.
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148
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Kreitzman M, Ashander J, Driscoll J, Bateman AW, Chan KMA, Lewis MA, Krkosek M. Wild Salmon Sustain the Effectiveness of Parasite Control on Salmon Farms: Conservation Implications from an Evolutionary Ecosystem Service. Conserv Lett 2017. [DOI: 10.1111/conl.12395] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Maayan Kreitzman
- Institute for Resources, Environment, and Sustainability; University of British Columbia; 429-2202 Main Mall (4th floor) Vancouver BC V6T 1Z4 Canada
| | - Jaime Ashander
- Department of Environmental Science & Policy; University of California; One Shields Ave Davis Davis CA 95616 USA
| | - John Driscoll
- Institute for Resources, Environment, and Sustainability; University of British Columbia; 429-2202 Main Mall (4th floor) Vancouver BC V6T 1Z4 Canada
| | - Andrew W Bateman
- Department of Biological Sciences, University of Alberta CW 405; Biological Sciences Bldg.; Edmonton AB T6G 2E9 Canada
- Salmon Coast Field Station; General Delivery, Simoom Sound BC V0P 1S0 Canada
| | - Kai M. A. Chan
- Institute for Resources, Environment, and Sustainability; University of British Columbia; 429-2202 Main Mall (4th floor) Vancouver BC V6T 1Z4 Canada
| | - Mark A. Lewis
- Department of Biological Sciences, University of Alberta CW 405; Biological Sciences Bldg.; Edmonton AB T6G 2E9 Canada
- Department of Mathematical and Statistical Sciences; University of Alberta; 545B CAB Edmonton AB T6G 2G1 Canada
| | - Martin Krkosek
- Salmon Coast Field Station; General Delivery, Simoom Sound BC V0P 1S0 Canada
- Department of Ecology and Evolutionary Biology; University of Toronto; 25 Willcocks Street Toronto Ontario M5S 3B2 Canada
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149
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Aldrin M, Huseby R, Stien A, Grøntvedt R, Viljugrein H, Jansen P. A stage-structured Bayesian hierarchical model for salmon lice populations at individual salmon farms – Estimated from multiple farm data sets. Ecol Modell 2017. [DOI: 10.1016/j.ecolmodel.2017.05.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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150
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Oppedal F, Samsing F, Dempster T, Wright DW, Bui S, Stien LH. Sea lice infestation levels decrease with deeper 'snorkel' barriers in Atlantic salmon sea-cages. PEST MANAGEMENT SCIENCE 2017; 73:1935-1943. [PMID: 28247541 DOI: 10.1002/ps.4560] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/13/2017] [Accepted: 02/22/2017] [Indexed: 05/04/2023]
Abstract
BACKGROUND Salmon lice (Lepeophtheirus salmonis) are the most important parasites of farmed salmon. Infective larvae position themselves in the upper part of the water column to increase encounter probabilities with potential hosts. Previous studies have shown that a 'snorkel' sea-cage technology protects salmon from infection in surface waters. We tested whether deep snorkels would more effectively reduce lice infestation than shallow snorkels and still uphold adequate conditions for the fish. Five sea-cages (12 m × 12 m) each holding approximately 3000 Atlantic salmon (Salmo salar) (53 ± 10 g) were fitted with snorkels that gave protection from infection for 0, 4, 8, 12 or 16 m. We tested whether reductions in the settlement of new salmon lice copepodids were consistent among four separate infection periods. RESULTS Lice infestation decreased exponentially with depth in all time periods. Infection levels in shallow snorkels (0 and 4 m) were consistently 4-10 times higher than those in deep snorkels (12 and 16 m). Key welfare and production performance indices were similar across all snorkel depths. CONCLUSION Deeper snorkels dramatically and consistently reduced infection levels of salmon lice compared with shallow snorkels, without consequences for fish welfare and production performance. Therefore, reducing salmon sea lice encounters using a depth-based barrier is a powerful management tool for salmon farming. © 2017 Society of Chemical Industry.
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Affiliation(s)
| | - Francisca Samsing
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Victoria, Australia
| | - Tim Dempster
- Institute of Marine Research, Matredal, Norway
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Victoria, Australia
| | - Daniel W Wright
- Institute of Marine Research, Matredal, Norway
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Victoria, Australia
| | - Samantha Bui
- Institute of Marine Research, Matredal, Norway
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Victoria, Australia
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