1
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Faber MN, Sojan JM, Saraiva M, van West P, Secombes CJ. Development of a 3D spheroid cell culture system from fish cell lines for in vitro infection studies: Evaluation with Saprolegnia parasitica. J Fish Dis 2021; 44:701-710. [PMID: 33434302 DOI: 10.1111/jfd.13331] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
Understanding the ways in which pathogens infect host cells is essential to improve and develop new treatment strategies. This study aimed to generate a novel in vitro infection model by establishing a reproducible 3D spheroid cell culture system that may lead to a reduced need for animals in fish disease research. 2D models (commonly cell lines) cannot replicate many key conditions of in vivo infections, but 3D spheroids have the potential to provide bridging technology between in vivo and in vitro systems. 3D spheroids were generated using cells from rainbow trout (Oncorhynchus mykiss) cell lines, RTG-2 and RTS-11. The RTG-2 spheroids were tested for their potential to be infected upon exposure to Saprolegnia parasitica spores. Positive infiltration of mycelia into the spheroids was verified by confocal microscopy. As a closer analogue of in vivo conditions encountered during infection, the straightforward model developed in this study shows promise as an additional tool that can be used to further our understanding of host-pathogen interactions for Saprolegnia and possibly a variety of other fish pathogens.
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Affiliation(s)
- Marc N Faber
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Jerry M Sojan
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Marcia Saraiva
- Aberdeen Oomycete Laboratory, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, UK
| | - Pieter van West
- Aberdeen Oomycete Laboratory, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, UK
| | - Christopher J Secombes
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen, UK
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2
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Mehrabi Z, Firouzbakhsh F, Rahimi-Mianji G, Paknejad H. Immunity and growth improvement of rainbow trout (Oncorhynchus mykiss) fed dietary nettle (Urtica dioica) against experimental challenge with Saprolegnia parasitica. Fish Shellfish Immunol 2020; 104:74-82. [PMID: 32446965 DOI: 10.1016/j.fsi.2020.05.050] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 05/14/2020] [Accepted: 05/19/2020] [Indexed: 06/11/2023]
Abstract
In this study, effects of nettle (Urtica dioica) on growth, immunity, and gene expressions were examined in rainbow trout after an 8-week feeding period. A total of 264 juvenile rainbow trout (10.72 ± 0.55 g) were selected and stocked randomly in 12 aquaria. Nettle powder was added to the fish feed at three doses, 0.5,1 and 1.5% served as treatments. At the end of 8-week feeding period, the fish were exposed to Saprolegnia parasitica for 3 weeks. Results showed that all treatments fed with nettle diets exhibited significant increases in weight gain and SGR, and decreased FCR compared to the control. Feeding the fish with dietary nettle resulted in significant rises in blood indices and non-specific immunity in comparison with the control. Furthermore, fish fed 0.5% of dietary nettle showed significantly increased expressions of TNF-α, IL-1b, IL-6 and IL-8 genes following 8 weeks of feeding. A significant reduction in mortality rate was observed in the fish treated with 0.5% of nettle compared to the control following challenging with S. parasitica. Our observations indicate that the use of 0.5% nettle powder in rainbow trout diet can improve growth and immunity parameters as well as fish resistance against S. parasitica contamination.
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Affiliation(s)
- Zibandeh Mehrabi
- Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran
| | - Farid Firouzbakhsh
- Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.
| | - Ghodrat Rahimi-Mianji
- Department of Animal Science, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran
| | - Hamed Paknejad
- Department of Fisheries, Faculty of Fisheries and Environmental Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
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3
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Greeff-Laubscher MR, Christison KW, Smit NJ. First Record of the Water Mold Achlya bisexualis (Saprolegniaceae) Isolated from Ornamental Fish in South Africa. J Aquat Anim Health 2019; 31:354-363. [PMID: 31765509 DOI: 10.1002/aah.10088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
The order Saprolegniales (Class Oomycota) is a group of fungus-like eukaryotic microorganisms that have been associated with infections in fish and fish eggs. Infections with microorganisms from this order are clearly evident because they have a cotton wool-like appearance. The aim of this study was to characterize and identify an oomycete that was isolated from the eye of an Orange Blotched Peacock Cichlid Aulonacara sp. A sample of cotton wool-like mycelia was isolated and single-spore isolations were conducted. Molecular characterization and phylogenetic analysis of the ITS1-5.8-ITS2 rDNA region for all isolates were used for species identification. Following molecular identification, one isolate was used to culture and characterize the reproductive structures. Physiological characterization entailed incubating the isolate on potato dextrose agar (PDA) at five different temperatures, ranging from 5°C to 25°C, to monitor growth rates. A multiple sequence alignment showed 100% similarity between all of the single-spore isolates and alignment with other Achlya bisexualis strains. Long, coarse hyphae with zoosporangia and gemmae typical of the order Saprolegniales were observed with an optimal growth rate at 25°C. The oomycete that was isolated from an Orange Blotched Peacock Cichlid was identified as A. bisexualis, the first record of this species in South Africa.
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Affiliation(s)
- Mariska Riana Greeff-Laubscher
- Water Research Group, Unit for Environmental Sciences and Management, Potchefstroom Campus, North West University, Private Bag X6001, Potchefstroom, 2520, South Africa
| | - Kevin William Christison
- Department of Agriculture, Forestry and Fisheries, Directorate Aquaculture Research, Private Bag X2, Vlaeberg, Cape Town, 8018, South Africa
- Biodiversity and Conservation Biology, University of the Western Cape, Private Bag X7, Bellville, 7535, South Africa
| | - Nicholas Jacobus Smit
- Water Research Group, Unit for Environmental Sciences and Management, Potchefstroom Campus, North West University, Private Bag X6001, Potchefstroom, 2520, South Africa
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4
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Aller-Gancedo JM, Fregeneda-Grandes JM. Distribution patterns of saprolegniosis cutaneous lesions in wild and farmed brown trout (Salmo trutta L.) obtained using a geographic information system (GIS). J Fish Dis 2019; 42:1419-1424. [PMID: 31411735 DOI: 10.1111/jfd.13070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/10/2019] [Accepted: 07/15/2019] [Indexed: 06/10/2023]
Abstract
A retrospective study was conducted using 250 clinical records of brown trout (Salmo trutta L.) with saprolegniosis by Saprolegnia parasitica, which had been collected from 8 rivers and 1 fish farm in the province of León (Spain). A geographic information system (GIS) was used to obtain skin lesion distribution patterns in males and females. Lesions in wild brown trout affected 15.31 ± 13.33% of the body surface, with a mean of 12.76 ± 6.56 lesions per fish. In addition, 51.23% of wild trout presented lesions with necrosis of the skin or fins. The pattern obtained when not distinguishing between sexes indicated that saprolegniosis lesions are mainly located above the lateral line and most frequently affect the dorsal cephalic region, the adipose fin, the peduncle and the caudal fin. However, differences were observed between males and females. Farmed trout presented a lower percentage of affected body surface (2.06 ± 4.36) and a lower number of lesions with and without necrosis because they received preventive treatment for saprolegniosis.
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Ali SE, Songe MM, Skaar I. Colorimetric assay for the in vitro evaluation of Saprolegnia biofilm inhibitors. J Fish Dis 2019; 42:1119-1124. [PMID: 31099066 DOI: 10.1111/jfd.13017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 04/10/2019] [Accepted: 04/14/2019] [Indexed: 06/09/2023]
Abstract
A quantitative and reproducible 96-well microtiter method that is easily adaptable for the screening of Saprolegnia biofilm inhibitors is described. As opposed to other methods previously developed for the screening of Saprolegnia inhibitors on spore germination or mycelial growth, this technique is of particular significance as it investigates potential inhibitors against surface-attached mycelial mats of Saprolegnia spp. (biofilm). In this study, we have investigated the effects of propionic acid (PPA) on reducing the viability of induced Saprolegnia biofilms using colorimetric MTS assay based on the reduction of tetrazolium salts. Viability of Saprolegnia hyphae in treated biofilms was reduced significantly following treatment with different PPA concentrations. The effect was enhanced after combining each of the tested PPA concentrations with 500 mg/L of boric acid (BA). However, the percentage of non-viable hyphae was still higher in 200 mg L-1 bronopol-treated biofilms (positive control) following 6- and 12-hr exposure. Similar results were observed using other recently described fluorescence-based assays for viability.
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Affiliation(s)
- Shimaa E Ali
- Department of Hydrobiology, National Research Centre, Giza, Egypt
- WorldFish, Cairo, Egypt
| | - Mwansa M Songe
- Ministry of Fisheries and Livestock, Department of Veterinary Services, Central Veterinary Research Institute, Lusaka, Zambia
| | - Ida Skaar
- Norwegian Veterinary Institute, Oslo, Norway
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Bonansea M, Mancini M, Ledesma M, Ferrero S, Rodriguez C, Pinotti L. Remote sensing application to estimate fish kills by Saprolegniasis in a reservoir. Sci Total Environ 2019; 669:930-937. [PMID: 30970459 DOI: 10.1016/j.scitotenv.2019.02.442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 02/27/2019] [Accepted: 02/27/2019] [Indexed: 06/09/2023]
Abstract
Saprolegniasis is one of the most economical and ecologically harmful diseases in different species of fish. Low water temperature is one of the most important factors which increases stress and creates favourable conditions for the proliferation of Saprolegniasis. Therefore, the monitoring of water surface temperature (WST) is fundamental for a better understanding of Saprolegniasis. The objective of this study was to develop a predictive algorithm to estimate the probability of fish kills caused by Saprolegniasis in Río Tercero reservoir (Argentina). WST was estimated by Landsat 7 and 8 imagery using the Single-Channel method. Logistic regression was used to relate WST estimated from 2007 to 2017 with different episodes of fish kills by Saprolegniasis registered in the reservoir during this period of time. Results showed that the algorithm created with the first quartile (25th percentile) of the WST values estimated by Landsat sensors was the most suitable model to estimate Saprolegniasis in the studied reservoir.
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Affiliation(s)
- Matias Bonansea
- Instituto de Ciencias de la Tierra, Biodiversidad y Sustentabilidad Ambiental (ICBIA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ruta Nacional 36 Km 601, 5800 Río Cuarto, Córdoba, Argentina; Departamento de Estudios Básico y Agropecuarios, Facultad de Agronomía y Veterinaria (FAyV), Universidad Nacional de Río Cuarto (UNRC), Argentina.
| | - Miguel Mancini
- Departamento de Estudios Básico y Agropecuarios, Facultad de Agronomía y Veterinaria (FAyV), Universidad Nacional de Río Cuarto (UNRC), Argentina
| | - Micaela Ledesma
- Departamento de Estudios Básico y Agropecuarios, Facultad de Agronomía y Veterinaria (FAyV), Universidad Nacional de Río Cuarto (UNRC), Argentina
| | - Susana Ferrero
- Departamento Matemática, Facultad de Ciencias Exactas, Físico-Químicas y Naturales (FCEFQyN), UNRC, Argentina
| | - Claudia Rodriguez
- Departamento de Estudios Básico y Agropecuarios, Facultad de Agronomía y Veterinaria (FAyV), Universidad Nacional de Río Cuarto (UNRC), Argentina
| | - Lucio Pinotti
- Instituto de Ciencias de la Tierra, Biodiversidad y Sustentabilidad Ambiental (ICBIA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ruta Nacional 36 Km 601, 5800 Río Cuarto, Córdoba, Argentina
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7
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Yu W, Luo Y, Yu Y, Dong S, Yin Y, Huang Z, Xu Z. T cell receptor (TCR) α and β genes of loach (Misgurnus anguillicaudatus): Molecular cloning and expression analysis in response to bacterial, parasitic and fungal challenges. Dev Comp Immunol 2019; 90:90-99. [PMID: 30205126 DOI: 10.1016/j.dci.2018.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/06/2018] [Accepted: 09/06/2018] [Indexed: 06/08/2023]
Abstract
In vertebrates, the T cell receptor (TCR) plays a crucial role in immune system. To date, the roles of fish TCRs in response to pathogen infection are still poorly understood. In the present study, we firstly cloned and identified the TCRα and TCRβ from dojo loach (Misgurnus anguillicaudatus) by RACE approaches. The full-length cDNAs of Ma-TCRα and Ma-TCRβ include an open reading frame (ORF) of 723 and 879 bp encoding a polypeptide of 241 and 293 amino acids, respectively. Structural analysis indicated that Ma-TCRα and Ma-TCRβ had a signal peptide, IgV domain, IgC domain, a connecting peptide (CPS), a transmembrane region (TM) and a cytoplasmic (CYT), which are similar to their counterparts described in other teleost. Phylogenetic analysis supported that Ma-TCR Cα and Ma-TCR Cβ were closely related to the Cα and Cβ region of Cyprinidae family, respectively. Transcriptional expression analysis indicated that Ma-TCRα and Ma-TCRβ mRNAs were ubiquitously expressed in a wide array of tissues and most abundantly found in skin, brain, kidney, gill and spleen. The expression patterns of Ma-TCRα and Ma-TCRβ after bacteria (F. columnare G4), parasite (Ichthyophthirius multifiliis) and fungus (Saprolegnia) infection were detected by qRT-PCR. Additionally, the morphological changes of gill and skin following the three infection models were investigated. The results clearly indicated that Ma-TCRα and Ma-TCRβ was significant up-regulated not only in spleen and kidney, but also in skin and gill. In summary, our present findings suggested that Ma-TCRα and Ma-TCRβ might play significantly roles in the modulation of immune response and protect loach from different pathogens infection.
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Affiliation(s)
- Wei Yu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, Hubei, 430070, China
| | - Yanzhi Luo
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, Hubei, 430070, China
| | - Yongyao Yu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, Hubei, 430070, China
| | - Shuai Dong
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, Hubei, 430070, China
| | - Yaxing Yin
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, Hubei, 430070, China
| | - Zhenyu Huang
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, Hubei, 430070, China
| | - Zhen Xu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, Hubei, 430070, China; Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Changde, 415000, China.
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8
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Kulatunga DCM, Dananjaya SHS, Nikapitiya C, Godahewa GI, Cho J, Kim CH, Lee J, De Zoysa M. Stress-immune responses and DNA protection function of thioredoxin domain containing 12 in zebrafish (Danio rerio). Fish Shellfish Immunol 2019; 84:1030-1040. [PMID: 30359749 DOI: 10.1016/j.fsi.2018.10.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/16/2018] [Accepted: 10/22/2018] [Indexed: 06/08/2023]
Abstract
Proteins with dithiol-disulfide oxidoreductase catalytic domain are well known for their capacity in the cellular redox homeostasis. In this study, we characterized the zebrafish thioredoxin domain containing 12 (Zftxndc12) gene, analyzed the transcriptional responses and studied the functional properties of its recombinant protein. Full-length cDNA of Zftxndc12 consists 519 bp coding region encoding 172 amino acids (AA) including the signal peptide. Highly consensus active motif (65WCGAC69) and probable ER retrieval motif (169GDEL172) were identified. Ubiquitous expression of Zftxndc12 mRNA was observed from one cell to juvenile stage as well as different organs of adult zebrafish. Moreover, whole mount in situ hybridization (WISH) results showed a higher expression of Zftxndc12 in primordial gills, central nerves system and eye. The tissue specific expression analysis (by qRT-PCR) also showed the highest expression in gills followed by brain in adult zebrafish. In larvae, up-regulated Zftxndc12 mRNA expression upon exposure to H2O2,Edwardsiella tarda and Saprolegnia parasitica suggests that it may involve in both stress and immune responses. Moreover, transcriptional expression of Zftxndc12 was up-regulated upon Streptococcus iniae challenge in gills of adult zebrafish. The recombinant ZfTxndc12 (rZfTxndc12) was overexpressed, purified and tested for its biological activities. Results revealed that rZfTxndc12 is able to reduce the DNA damage and detoxify the H2O2 toxicity in concentration dependent manner. Overall results suggest that Zftxndc12 is important antioxidant and immune functional member of the host defense system in zebrafish.
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Affiliation(s)
- D C M Kulatunga
- College of Veterinary Medicine, Chungnam National University, Yuseong-gu, Daejeon, 34134, Republic of Korea
| | - S H S Dananjaya
- College of Veterinary Medicine, Chungnam National University, Yuseong-gu, Daejeon, 34134, Republic of Korea
| | - Chamilani Nikapitiya
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea
| | - G I Godahewa
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea
| | - Jongki Cho
- College of Veterinary Medicine, Chungnam National University, Yuseong-gu, Daejeon, 34134, Republic of Korea
| | - Cheol-Hee Kim
- Department of Biology, Chungnam National University, Yuseong-gu, Daejeon, 34134, Republic of Korea
| | - Jehee Lee
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea
| | - Mahanama De Zoysa
- College of Veterinary Medicine, Chungnam National University, Yuseong-gu, Daejeon, 34134, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea.
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9
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Trusch F, Loebach L, Wawra S, Durward E, Wuensch A, Iberahim NA, de Bruijn I, MacKenzie K, Willems A, Toloczko A, Diéguez-Uribeondo J, Rasmussen T, Schrader T, Bayer P, Secombes CJ, van West P. Cell entry of a host-targeting protein of oomycetes requires gp96. Nat Commun 2018; 9:2347. [PMID: 29904064 PMCID: PMC6002402 DOI: 10.1038/s41467-018-04796-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 05/11/2018] [Indexed: 12/02/2022] Open
Abstract
The animal-pathogenic oomycete Saprolegnia parasitica causes serious losses in aquaculture by infecting and killing freshwater fish. Like plant-pathogenic oomycetes, S. parasitica employs similar infection structures and secretes effector proteins that translocate into host cells to manipulate the host. Here, we show that the host-targeting protein SpHtp3 enters fish cells in a pathogen-independent manner. This uptake process is guided by a gp96-like receptor and can be inhibited by supramolecular tweezers. The C-terminus of SpHtp3 (containing the amino acid sequence YKARK), and not the N-terminal RxLR motif, is responsible for the uptake into host cells. Following translocation, SpHtp3 is released from vesicles into the cytoplasm by another host-targeting protein where it degrades nucleic acids. The effector translocation mechanism described here, is potentially also relevant for other pathogen-host interactions as gp96 is found in both animals and plants.
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Grants
- BB/E007120/1 Biotechnology and Biological Sciences Research Council
- BB/G012075/1 Biotechnology and Biological Sciences Research Council
- Biotechnology and Biological Sciences Research Council (BBSRC)
- Deutsche Forschungsgemeinschaft (German Research Foundation)
- Our work is supported by the [European Community's] Seventh Framework Programme [FP7/2007-2013] under grant agreement no [238550] (LL, JDU, CJS, PvW); BBSRC [BBE007120/1, BB/J018333/1 and BB/G012075/1] (FT, IdB, CJS, SW, PvW); Newton Global partnership Award [BB/N005058/1] (FT, PvW), the University of Aberdeen (ADT, TR, CJS, PvW) and Deutsche Forschungsgemeinschaft [CRC1093] (PB, TS). We would like to acknowledge the Ministry of Higher Education Malaysia for funding INA. We would like to thank Brian Haas for his bioinformatics support. We would like to acknowledge Neil Gow and Johannes van den Boom for critical reading of the manuscript. We would like to acknowledge Svetlana Rezinciuc for technical help with pH-studies.
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Affiliation(s)
- Franziska Trusch
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
- International Centre for Aquaculture Research and Development (ICARD), University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | - Lars Loebach
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | - Stephan Wawra
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
- Botanical Institute, Genetical Institute, University of Cologne, Cologne, 50674, Germany
| | - Elaine Durward
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
- International Centre for Aquaculture Research and Development (ICARD), University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | - Andreas Wuensch
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
- International Centre for Aquaculture Research and Development (ICARD), University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | - Nurul Aqilah Iberahim
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
- International Centre for Aquaculture Research and Development (ICARD), University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
- School of Fisheries and Aquaculture Sciences, Universiti Malaysia Terengganu, 21030, Kuala Terengganu, Terengganu, Malaysia
| | - Irene de Bruijn
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
- Netherlands Institute for Ecology (NIOO), Wageningen, 6708 PB, Netherlands
| | - Kevin MacKenzie
- Microscopy and Histology Facility, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | - Ariane Willems
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | - Aleksandra Toloczko
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | | | - Tim Rasmussen
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
| | - Thomas Schrader
- Organic Chemistry, University of Duisburg-Essen, Essen, 45117, Germany
| | - Peter Bayer
- Structural and Medicinal Biochemistry, Centre for Medical Biotechnology (ZMB), University of Duisburg-Essen, Essen, 45117, Germany
| | - Chris J Secombes
- International Centre for Aquaculture Research and Development (ICARD), University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK
- Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, Scotland, UK
| | - Pieter van West
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK.
- International Centre for Aquaculture Research and Development (ICARD), University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, UK.
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Khan MIR, Saha RK, Saha H. Muli bamboo (Melocanna baccifera) leaves ethanolic extract a non-toxic phyto-prophylactic against low pH stress and saprolegniasis in Labeo rohita fingerlings. Fish Shellfish Immunol 2018; 74:609-619. [PMID: 29183812 DOI: 10.1016/j.fsi.2017.11.047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 11/22/2017] [Accepted: 11/24/2017] [Indexed: 06/07/2023]
Abstract
Bamboo (Melocanna baccifera) plant plays a significant role in traditional Asian medicine and it can be used as an alternative to various chemo-therapeutics or prophylactic agents used in aquaculture. In the present study, the 1st experiment was done for the preparation of extracts from bamboo leaves by using 90% alcohol as a solvent. In the 2nd experiment, toxicity study was carried on Labeo rohita fingerlings (average length of 10.3 ± 1.5 cm and weight 18.5 ± 1.5 g) using BLAL (Bamboo Leaf Alcoholic) extract and it did not show any mortalities in fish even at the dose of 20 g kg-1 body weight, which can be regarded as virtually non-toxic with minimal effect. The 3rd experiment was conducted to find out the effect of BLAL extract based isocaloric and isonitrogenous feed (doses: control- 0.0%, diet T1-0.01%, diet T2-0.1%, diet T3-1% BLAL extract kg-1 feed) on the haemato-immuno-biochemical parameters of L. rohita fingerlings (average length 15.7 ± 1.5 cm and weight 20.2 ± 1.5 g). Regular sampling was done (on 7th, 15th, 30th and 60th day of feeding) for different haematological, immunological and biochemical parameters. The study revealed that the best response occurred within 7 days of feeding with BLAL extract and long-term feeding have shown immunosuppressive condition in the fish. In the 4th experiment, fish were exposed to multiple stressors like low pH stress, and Saprolegnia parastica infection after feeding with BLAL extract (0.1%) based feed for 7 days. The study showed that the BLAL extract can make fish resistant to single stress however, not able to reduce the fish mortality under multiple stresses (S. parastica infection under low pH). Thus, it can be concluded that the BLAL has the potentiality to be used as a non-toxic phyto-prophylactic which can induce non-specific immune response, reduces the low pH stress responses and increases the resistance against saprolegniasis under neutral pH condition in rohu fingerlings.
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Affiliation(s)
- Md Idrish Raja Khan
- Department of Aquatic Health and Environment, College of Fisheries, CAU, Lembucherra, Agartala, Tripura-799210, India
| | - Ratan Kumar Saha
- Department of Aquatic Health and Environment, College of Fisheries, CAU, Lembucherra, Agartala, Tripura-799210, India
| | - Himadri Saha
- Department of Aquatic Health and Environment, College of Fisheries, CAU, Lembucherra, Agartala, Tripura-799210, India.
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11
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Stewart A, Hablützel PI, Brown M, Watson HV, Parker-Norman S, Tober AV, Thomason AG, Friberg IM, Cable J, Jackson JA. Half the story: Thermal effects on within-host infectious disease progression in a warming climate. Glob Chang Biol 2018; 24:371-386. [PMID: 28746785 DOI: 10.1111/gcb.13842] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 07/12/2017] [Indexed: 06/07/2023]
Abstract
Immune defense is temperature dependent in cold-blooded vertebrates (CBVs) and thus directly impacted by global warming. We examined whether immunity and within-host infectious disease progression are altered in CBVs under realistic climate warming in a seasonal mid-latitude setting. Going further, we also examined how large thermal effects are in relation to the effects of other environmental variation in such a setting (critical to our ability to project infectious disease dynamics from thermal relationships alone). We employed the three-spined stickleback and three ecologically relevant parasite infections as a "wild" model. To generate a realistic climatic warming scenario we used naturalistic outdoors mesocosms with precise temperature control. We also conducted laboratory experiments to estimate thermal effects on immunity and within-host infectious disease progression under controlled conditions. As experimental readouts we measured disease progression for the parasites and expression in 14 immune-associated genes (providing insight into immunophenotypic responses). Our mesocosm experiment demonstrated significant perturbation due to modest warming (+2°C), altering the magnitude and phenology of disease. Our laboratory experiments demonstrated substantial thermal effects. Prevailing thermal effects were more important than lagged thermal effects and disease progression increased or decreased in severity with increasing temperature in an infection-specific way. Combining laboratory-determined thermal effects with our mesocosm data, we used inverse modeling to partition seasonal variation in Saprolegnia disease progression into a thermal effect and a latent immunocompetence effect (driven by nonthermal environmental variation and correlating with immune gene expression). The immunocompetence effect was large, accounting for at least as much variation in Saprolegnia disease as the thermal effect. This suggests that managers of CBV populations in variable environments may not be able to reliably project infectious disease risk from thermal data alone. Nevertheless, such projections would be improved by primarily considering prevailing thermal effects in the case of within-host disease and by incorporating validated measures of immunocompetence.
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Affiliation(s)
| | - Pascal I Hablützel
- IBERS, Aberystwyth University, Aberystwyth, UK
- Flanders Marine Institute, Oostende, Belgium
- Laboratory of Biodiversity and Evolutionary Genomics, Biology Department, University of Leuven, Leuven, Belgium
| | | | - Hayley V Watson
- IBERS, Aberystwyth University, Aberystwyth, UK
- School of Environmental Sciences, University of Hull, Hull, UK
| | | | - Anya V Tober
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Anna G Thomason
- School of Environment and Life Sciences, University of Salford, Salford, UK
| | - Ida M Friberg
- School of Environment and Life Sciences, University of Salford, Salford, UK
| | - Joanne Cable
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Joseph A Jackson
- School of Environment and Life Sciences, University of Salford, Salford, UK
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Derevnina L, Petre B, Kellner R, Dagdas YF, Sarowar MN, Giannakopoulou A, De la Concepcion JC, Chaparro-Garcia A, Pennington HG, van West P, Kamoun S. Emerging oomycete threats to plants and animals. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150459. [PMID: 28080985 PMCID: PMC5095538 DOI: 10.1098/rstb.2015.0459] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2016] [Indexed: 12/31/2022] Open
Abstract
Oomycetes, or water moulds, are fungal-like organisms phylogenetically related to algae. They cause devastating diseases in both plants and animals. Here, we describe seven oomycete species that are emerging or re-emerging threats to agriculture, horticulture, aquaculture and natural ecosystems. They include the plant pathogens Phytophthora infestans, Phytophthora palmivora, Phytophthora ramorum, Plasmopara obducens, and the animal pathogens Aphanomyces invadans, Saprolegnia parasitica and Halioticida noduliformans For each species, we describe its pathology, importance and impact, discuss why it is an emerging threat and briefly review current research activities.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'.
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Affiliation(s)
- Lida Derevnina
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Benjamin Petre
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Ronny Kellner
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne 50829, Germany
| | - Yasin F Dagdas
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Mohammad Nasif Sarowar
- Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | | | | | | | | | - Pieter van West
- International Centre for Aquaculture Research and Development, Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Sophien Kamoun
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
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13
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Pereira-Torres D, Gonçalves AT, Ulloa V, Martínez R, Carrasco H, Olea AF, Espinoza L, Gallardo-Escárate C, Astuya A. In vitro modulation of Drimys winteri bark extract and the active compound polygodial on Salmo salar immune genes after exposure to Saprolegnia parasitica. Fish Shellfish Immunol 2016; 59:103-108. [PMID: 27777106 DOI: 10.1016/j.fsi.2016.10.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/11/2016] [Accepted: 10/18/2016] [Indexed: 06/06/2023]
Abstract
The rapid development of the aquaculture industry has global concerns with health management and control strategies to prevent and/or treat diseases and increase sustainability standards. Saprolegniosis is a disease caused by Saprolegnia parasitica, and is characterized by promoting an immunosuppression in the host. This study evaluated in vitro the extract and one active compound (polygodial) of Drimys winteri, a Chilean medicinal tree as a potential early immunostimulatory aid in Saprolegniosis control. Atlantic salmon (Salmo salar) head kidney cells (ASK-1) were incubated with both extract and pure polygodial before exposure to S. parasitica mycelium, and the expression of the immune-related genes interleukin 1β (IL-1β), interferon α (IFNα), and major histocompatibility complex II (MHCII) was evaluated. Both evidenced immunomodulatory capacities by increasing gene expressions. This immunomodulation related to a mitigatory action counteracting the immunosuppressing effects of S. parasitica. Despite that most immune-related genes were up-regulated, the down-regulation of MHCII, characteristic of S. parasitica infection, was lessened by pre-incubation with the compounds. This study provides the first insight on the potential of D. winteri bark extract as a possible immunomodulatory and defensive strategy against this oomycete infection in fish.
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Affiliation(s)
- D Pereira-Torres
- Laboratory of Cell Culture and Marine Genomics, Department of Oceanography and COPAS Sur-Austral, University of Concepción, Casilla 160-C, Concepción, Chile
| | - A T Gonçalves
- Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, Casilla 160-C, Concepción, Chile
| | - V Ulloa
- Laboratory of Cell Culture and Marine Genomics, Department of Oceanography and COPAS Sur-Austral, University of Concepción, Casilla 160-C, Concepción, Chile
| | - R Martínez
- Departamento de Química, Facultad de Ciencias Exactas, Universidad Andrés Bello, Quillota 910, Viña del Mar, Chile
| | - H Carrasco
- Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, Llano Subercaseaux 2801, San Miguel, Santiago, Chile
| | - A F Olea
- Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, Llano Subercaseaux 2801, San Miguel, Santiago, Chile
| | - L Espinoza
- Departamento de Química, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso, Chile
| | - C Gallardo-Escárate
- Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, Casilla 160-C, Concepción, Chile
| | - A Astuya
- Laboratory of Cell Culture and Marine Genomics, Department of Oceanography and COPAS Sur-Austral, University of Concepción, Casilla 160-C, Concepción, Chile.
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14
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Saha H, Pal AK, Sahu NP, Saha RK. Feeding pyridoxine prevents Saprolegnia parasitica infection in fish Labeo rohita. Fish Shellfish Immunol 2016; 59:382-388. [PMID: 27670085 DOI: 10.1016/j.fsi.2016.09.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 09/14/2016] [Accepted: 09/22/2016] [Indexed: 06/06/2023]
Abstract
A 60-day experiment was carried out to delineate the role of dietary pyridoxine (DP) in Labeo rohita fingerlings in modulating immunity and prevention of fungal infection. Two hundred and seventy fingerlings were randomly distributed into three treatments in triplicates. Three iso-caloric and iso-nitrogenous purified diets were prepared with graded levels of pyridoxine. Three experimental groups were C (0.0% DP), T1 (0.01% DP) and T2 (0.02% DP). The role of dietary pyridoxine in modulating immunity and prevention of fungal infection was assessed by haemato-immunological parameters like erythrocyte counts (EC), leucocyte counts (LC), haemoglobulin (Hb), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), nitro-blue tetrazolium (NBT), phagocytic activity, albumin, globulin, total plasma protein, albumin/globulin and by challenge study with Saprolegnia parasitica, where relative percentage survival (RPS) were recorded. Hb, PCV, MCV, MCH, NBT, total plasma protein, albumin, globulin contents, lysozyme and phagocytic activity was significantly (P < 0.05) higher in DP fed group. Significantly (P < 0.05) higher RPS was recorded from T2 group fed with 0.02% DP for 45 days. Hence, DP has the capacity to stimulate nonspecific immunity and increase resistance to S. parasitica infection in L. rohita fingerlings.
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Affiliation(s)
- Himadri Saha
- Division of Fish Nutrition, Biochemistry and Physiology, Central Institute of Fisheries Education, Mumbai, Maharashtra, 400061, India; Department of Aquatic Health and Environment, College of Fisheries, CAU, Lembucherra, Agartala, Tripura, 799210, India.
| | - Asim Kumar Pal
- Division of Fish Nutrition, Biochemistry and Physiology, Central Institute of Fisheries Education, Mumbai, Maharashtra, 400061, India
| | - Narottam Prasad Sahu
- Division of Fish Nutrition, Biochemistry and Physiology, Central Institute of Fisheries Education, Mumbai, Maharashtra, 400061, India.
| | - Ratan Kumar Saha
- Department of Aquatic Health and Environment, College of Fisheries, CAU, Lembucherra, Agartala, Tripura, 799210, India
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15
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Zahran E, Manning B, Seo JK, Noga EJ. The effect of Ochratoxin A on antimicrobial polypeptide expression and resistance to water mold infection in channel catfish (Ictalurus punctatus). Fish Shellfish Immunol 2016; 57:60-67. [PMID: 27539704 DOI: 10.1016/j.fsi.2016.08.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 08/08/2016] [Accepted: 08/13/2016] [Indexed: 06/06/2023]
Abstract
Mycotoxin contamination of agricultural commodities poses a serious risk to animal health, including aquaculture species. Ochratoxin A (OA) is the most immunotoxic ochratoxin, yet little is known about its effect on immune function in fish. Antimicrobial polypeptides (AMPPs) are one of the most potent, innate, host defense factors, yet very little is known about what types of chronic stressors affect their expression. Among the most prevalent and potent AMPPs in fish are histone-like proteins (HLPs). In this study, fish were fed 2, 4, or 8 mg OA/kg diet. Skin antibacterial activity and HLP-1 levels were measured on Days 0, 28 and 56. Feeding 2, 4 or 8 mg OA/kg diet resulted in significant growth depression, but higher levels (4 or 8 mg OA/kg diet) resulted in lowering feed intake (FI) and impaired feed conversion ratio. In addition, feeding 8 mg OA/kg diet increased susceptibility to experimental water mold (Saprolegnia) challenge, suggesting that OA toxicity might contribute to some saprolegnosis outbreaks. However, there were no changes in AMPP expression in any treatment group. Our data suggests that the increased disease susceptibility of channel catfish due to OA is probably due to mechanisms other than a direct effect on antimicrobial polypeptide expression.
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Affiliation(s)
- Eman Zahran
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA, 27606.
| | - Bruce Manning
- National Warmwater Aquaculture Center, Mississippi State University, Stoneville, MS, 38776, USA
| | - Jung-Kil Seo
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA, 27606
| | - Edward J Noga
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA, 27606
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16
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Songe MM, Willems A, Sarowar MN, Rajan K, Evensen Ø, Drynan K, Skaar I, van West P. A thicker chorion gives ova of Atlantic salmon (Salmo salar L.) the upper hand against Saprolegnia infections. J Fish Dis 2016; 39:879-888. [PMID: 26644366 DOI: 10.1111/jfd.12421] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 08/31/2015] [Accepted: 09/03/2015] [Indexed: 06/05/2023]
Abstract
Since the ban of malachite green in the fish farming industry, finding alternative ways of controlling Saprolegnia infections has become of utmost importance. Much effort has been made to elucidate the mechanisms by which Saprolegnia invades fish eggs. Little is known about the defence mechanisms of the hosts, making some eggs more prone to infection than others. One clue might lie in the composition of the eggs. As the immune system in the embryos is not developed yet, the difference in infection levels could be explained by factors influenced by the mother herself, by either transferring passive immunity, influencing the physical aspects of the eggs or both. One of the physical aspects that could be influenced by the female is the chorion, the extracellular coat surrounding the fish egg, which is in fact the first major barrier to be overcome by Saprolegnia spp. Our results suggest that a thicker chorion in eggs from Atlantic salmon gives a better protection against Saprolegnia spp. In addition to the identification of differences in sensitivity of eggs in a fish farm set-up, we were able to confirm these results in a laboratory-controlled challenge experiment.
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Affiliation(s)
- M M Songe
- Norwegian Veterinary Institute, Oslo, Norway
| | - A Willems
- Aberdeen Oomycete Laboratory, College of Life Sciences and Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - M N Sarowar
- Aberdeen Oomycete Laboratory, College of Life Sciences and Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - K Rajan
- Landcatch Natural Selection Ltd, Ormsary Fish Farm, Lochgilphead, Argyll, UK
| | - Ø Evensen
- Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway
| | - K Drynan
- Landcatch Natural Selection Ltd, Ormsary Fish Farm, Lochgilphead, Argyll, UK
| | - I Skaar
- Norwegian Veterinary Institute, Oslo, Norway
| | - P van West
- Aberdeen Oomycete Laboratory, College of Life Sciences and Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
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17
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Songe MM, Willems A, Wiik‐Nielsen J, Thoen E, Evensen Ø, van West P, Skaar I. Saprolegnia diclina IIIA and S. parasitica employ different infection strategies when colonizing eggs of Atlantic salmon, Salmo salar L. J Fish Dis 2016; 39:343-52. [PMID: 25846807 PMCID: PMC4973706 DOI: 10.1111/jfd.12368] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/20/2015] [Accepted: 02/09/2015] [Indexed: 05/23/2023]
Abstract
Here, we address the morphological changes of eyed eggs of Atlantic salmon, Salmo salar L. infected with Saprolegnia from a commercial hatchery and after experimental infection. Eyed eggs infected with Saprolegnia spp. from 10 Atlantic salmon females were obtained. Egg pathology was investigated by light and scanning electron microscopy. Eggs from six of ten females were infected with S. parasitica, and two females had infections with S. diclina clade IIIA; two Saprolegnia isolates remained unidentified. Light microscopy showed S. diclina infection resulted in the chorion in some areas being completely destroyed, whereas eggs infected with S. parasitica had an apparently intact chorion with hyphae growing within or beneath the chorion. The same contrasting pathology was found in experimentally infected eggs. Scanning electron microscopy revealed that S. parasitica grew on the egg surface and hyphae were found penetrating the chorion of the egg, and re-emerging on the surface away from the infection site. The two Saprolegnia species employ different infection strategies when colonizing salmon eggs. Saprolegnia diclina infection results in chorion destruction, while S. parasitica penetrates intact chorion. We discuss the possibility these infection mechanisms representing a necrotrophic (S. diclina) vs. a facultative biotrophic strategy (S. parasitica).
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Affiliation(s)
- M M Songe
- Norwegian Veterinary InstituteOsloNorway
| | - A Willems
- Aberdeen Oomycete LaboratoryCollege of Life Sciencesand Medicine, Institute of Medical SciencesUniversity of AberdeenAberdeenUK
| | | | - E Thoen
- Norwegian Veterinary InstituteOsloNorway
| | - Ø Evensen
- Faculty of Veterinary Medicine and BiosciencesNorwegian University of Life SciencesOsloNorway
| | - P van West
- Aberdeen Oomycete LaboratoryCollege of Life Sciencesand Medicine, Institute of Medical SciencesUniversity of AberdeenAberdeenUK
| | - I Skaar
- Norwegian Veterinary InstituteOsloNorway
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18
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Ali SE, Thoen E, Evensen Ø, Wiik-Nielsen J, Gamil AAA, Skaar I. Mitochondrial dysfunction is involved in the toxic activity of boric acid against Saprolegnia. PLoS One 2014; 9:e110343. [PMID: 25354209 PMCID: PMC4212911 DOI: 10.1371/journal.pone.0110343] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 09/20/2014] [Indexed: 12/23/2022] Open
Abstract
There has been a significant increase in the incidence of Saprolegnia infections over the past decades, especially after the banning of malachite green. Very often these infections are associated with high economic losses in salmonid farms and hatcheries. The use of boric acid to control the disease has been investigated recently both under in vitro and in vivo conditions, however its possible mode of action against fish pathogenic Saprolegnia is not known. In this study, we have explored the transformation in Saprolegnia spores/hyphae after exposure to boric acid (1 g/L) over a period 4-24 h post treatment. Using transmission electron microscopy (TEM), early changes in Saprolegnia spores were detected. Mitochondrial degeneration was the most obvious sign observed following 4 h treatment in about 20% of randomly selected spores. We also investigated the effect of the treatment on nuclear division, mitochondrial activity and function using confocal laser scanning microscopy (CLSM). Fluorescence microscopy was also used to test the effect of treatment on mitochondrial membrane potential and formation of reactive oxygen species. Additionally, the viability and proliferation of treated spores that correlated to mitochondrial enzymatic activity were tested using an MTS assay. All obtained data pointed towards changes in the mitochondrial structure, membrane potential and enzymatic activity following treatment. We have found that boric acid has no effect on the integrity of membranes of Saprolegnia spores at concentrations tested. It is therefore likely that mitochondrial dysfunction is involved in the toxic activity of boric acid against Saprolegnia spp.
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Affiliation(s)
| | - Even Thoen
- Norwegian Veterinary Institute, Oslo, Norway
- Norwegian University of Life Sciences, Oslo, Norway
| | | | | | | | - Ida Skaar
- Norwegian Veterinary Institute, Oslo, Norway
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19
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Ali SE, Thoen E, Evensen Ø, Skaar I. Boric acid inhibits germination and colonization of Saprolegnia spores in vitro and in vivo. PLoS One 2014; 9:e91878. [PMID: 24699283 PMCID: PMC3974685 DOI: 10.1371/journal.pone.0091878] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 02/17/2014] [Indexed: 11/18/2022] Open
Abstract
Saprolegnia infections cause severe economic losses among freshwater fish and their eggs. The banning of malachite green increased the demand for finding effective alternative treatments to control the disease. In the present study, we investigated the ability of boric acid to control saprolegniosis in salmon eggs and yolk sac fry. Under in vitro conditions, boric acid was able to decrease Saprolegnia spore activity and mycelial growth in all tested concentrations above 0.2 g/L, while complete inhibition of germination and growth was observed at a concentration of 0.8 g/L. In in vivo experiments using Atlantic salmon eyed eggs, saprolegniosis was controlled by boric acid at concentrations ranging from 0.2-1.4 g/L during continuous exposure, and at 1.0-4.0 g/L during intermittent exposure. The same effect was observed on salmon yolk sac fry exposed continuously to 0.5 g/L boric acid during the natural outbreak of saprolegniosis. During the experiments no negative impact with regard to hatchability and viability was observed in either eggs or fry, which indicate safety of use at all tested concentrations. The high hatchability and survival rates recorded following the in vivo testing suggest that boric acid is a candidate for prophylaxis and control of saprolegniosis.
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Affiliation(s)
| | - Even Thoen
- Norwegian Veterinary Institute, Oslo, Norway
- Norwegian School of Veterinary Science, Oslo, Norway
| | | | - Ida Skaar
- Norwegian Veterinary Institute, Oslo, Norway
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20
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Kiseleva M, Balabanova L, Elyakova L, Rasskazov V, Zvyagintseva T. Effect of treatment of chum salmon Oncorhynchus keta (Walbaum) eggs with 1,3;1,6-β-D-glucans on their development and susceptibility to Saprolegnia infection. J Fish Dis 2014; 37:3-10. [PMID: 24205970 DOI: 10.1111/jfd.12043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 09/26/2008] [Accepted: 03/06/2009] [Indexed: 06/02/2023]
Abstract
The effects of six 1,3;1,6-β-D-glucooligo- and polysaccharides with different structures (ranging from 1 to 10 kDa in molecular mass and containing 10-25% of β-1,6-linked glucose residues) from brown algae, Saccharina cichorioides, on development of the chum salmon, Oncorhynchus keta (Walbaum), were evaluated. Exposure of chum salmon eggs to 1,3;1,6-β-D-glucans with a molecular mass of more than 2 kDa increased the survival of embryos and juveniles and their resistance to Saprolegnia infection by up to 2.5-fold, leading to a weight gain in juveniles of 40-55% compared with The control chum salmons. The 1,3;1,6-β-D-glucans with molecular mass of 6-8 kDa and used at a at concentration of 0.5 mg mL(-1) rendered the best stimulative effect.
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Affiliation(s)
- M Kiseleva
- Pacific Institute of Bioorganic Chemistry, Far-Eastern Branch of the Academy of Sciences, Vladivostok, Russia
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de Bruijn I, Belmonte R, Anderson VL, Saraiva M, Wang T, van West P, Secombes CJ. Immune gene expression in trout cell lines infected with the fish pathogenic oomycete Saprolegnia parasitica. Dev Comp Immunol 2012; 38:44-54. [PMID: 22522286 DOI: 10.1016/j.dci.2012.03.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 03/30/2012] [Accepted: 03/30/2012] [Indexed: 05/31/2023]
Abstract
The oomycete Saprolegnia parasitica causes significant losses in the aquaculture industry, mainly affecting salmon, trout and catfish. Since the ban of malachite green, effective control measures are currently not available prompting a re-evaluation of the potential for immunological intervention. In this study, the immune response of salmonid cells is investigated at the transcript level, by analysis of a large set of immune response genes in four different rainbow trout cell lines (RTG-2, RTGill, RTL and RTS11) upon infection with S. parasitica. Proinflammatory cytokine transcripts were induced in all four cell lines, including IL-1β1, IL-8, IL-11, TNF-α2, as well as other components of the innate defences, including COX-2, the acute phase protein serum amyloid A and C-type lectin CD209a and CD209b. However, differences between the four cell lines were found. For example, the fold change of induction was much higher in the epithelial RTL and macrophage-like RTS11 cell lines compared to the fibroblast cell lines RTG-2 and RTGill. Several antimicrobial peptides (AMPs) were also up-regulated in response to Saprolegnia infection, including hepcidin and cathelicidin 1 (rtCATH1) and 2 (rtCATH2). An rtCATH2 peptide was synthesised and tested for activity and whilst it showed no killing activity for zoospores, it was able to delay sporulation of S. parasitica. These results demonstrate that particular immune genes are up-regulated in response to S. parasitica infection and that AMPs may play a crucial role in the first line of defence against oomycetes in fish.
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Affiliation(s)
- Irene de Bruijn
- Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
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22
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Das SK, Murmu K, Das A, Shakuntala I, Das RK, Ngachan SV, Majhi SK. Studies on the identification and control of pathogen Saprolegnia in selected Indian major carp fingerlings at mid hill altitude. J Environ Biol 2012; 33:545-549. [PMID: 23029901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The Indian major carp cultured in ponds in the North Eastern hilly states of India frequently suffer from fungal disease during winter months resulting in mass mortality. This study examined the pathogenic fungi isolated from farmed raised Indian major carp fingerlings and identified as Saprolegnia. For treatment, the diseased fish were exposed to 4g salt per litre of water for 2 min followed by dip treatment with 5ppm KMnO4 for 10 min, thrice every week for a period of 6 weeks. The treatment resulted in recovery from the disease after 6 weeks from the beginning of treatment. Soon after recovery, the pond management practices such as removal of pond bottom soil, application of lime and replenishment with freshwater were followed in the infected ponds. Our study concluded that rapid decrease in pond water temperature from 22 to 8 degrees C that remains low for months together coupled with increased water pH (9) and decreas dissolved oxygen (4ppm) causes saprolegniasis to the fingerlings of Indian major carps.
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Affiliation(s)
- S K Das
- ICAR Complex for North Eastern Hill Region, Barapani-793 103, India
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23
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Carbajal-González MT, Fregeneda-Grandes JM, Suárez-Ramos S, Rodríguez Cadenas F, Aller-Gancedo JM. Bacterial skin flora variation and in vitro inhibitory activity against Saprolegnia parasitica in brown and rainbow trout. Dis Aquat Organ 2011; 96:125-135. [PMID: 22013752 DOI: 10.3354/dao02391] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Variations in the number and diversity of bacteria from the skin of brown trout Salmo trutta L. and rainbow trout Oncorhynchus mykiss Walbaum were surveyed from different rivers and fish farms in northern Spain. In addition to determining bacterial populations in skin samples of healthy fish, bacterial populations were determined from skin lesions (of brown trout only) infected with Saprolegnia parasitica, the causal agent of saprolegniosis. Mean bacterial counts from skin lesions of brown trout suffering from saprolegniosis were nearly 1000 times greater than from the skin of uninfected brown and rainbow trout. More than 20 different genera of bacteria were identified, with isolates of Aeromonas and Iodobacter being the predominant genera associated with saprolegniosis lesions. The in vitro inhibitory activity of 72 of these skin isolates was tested against S. parasitica using 3 different assays. These included (1) assessing the inhibition by bacteria of colony growth on agar media, (2) the inhibition of colony growth from colonized hemp seeds in liquid media and (3) the inhibition of cyst germination in liquid media. Finally, the fungicidal effect of the 24 most inhibitory bacterial species, and the inhibitory activity of their culture supernatants, was tested in the same way. Isolates identified as Aeromonas piscicola, A. sobria, Pantoea agglomerans and Pseudomonas fluorescens achieved the highest inhibition against S. parasitica. Many of these inhibitory isolates were obtained primarily from skin lesions of fish with saprolegniosis. It is suggested that some of these isolates might be useful in the biological control of saprolegniosis.
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Affiliation(s)
- M T Carbajal-González
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de León, 24071 León, Spain
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Romansic JM, Diez KA, Higashi EM, Johnson JE, Blaustein AR. Effects of the pathogenic water mold Saprolegnia ferax on survival of amphibian larvae. Dis Aquat Organ 2009; 83:187-193. [PMID: 19402452 DOI: 10.3354/dao02007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Infectious diseases are a significant threat to worldwide biodiversity. Amphibian declines, a significant part of current biodiversity losses, are in many cases associated with infectious disease. Water molds are one group of pathogens affecting amphibians on a worldwide basis. Although water molds have been studied extensively for their effects on host embryos, little information is available about how they affect post-embryonic amphibians. We tested the effects of one species of water mold, Saprolegnia ferax, in a comparative study of larvae of 4 amphibian species: Pseudacris regilla (Pacific treefrog), Rana cascadae (Cascades frog), Ambystoma macrodactylum (long-toed salamander), and R. aurora (red-legged frog). S. ferax can kill amphibians at the embryonic and juvenile life history stages, depending on the amphibian species. In the present study, a 1 wk exposure to S. ferax killed P. regilla larvae and a 2 wk exposure killed R. aurora larvae. Larvae of the other host species were unaffected after 1 wk of exposure to S. ferax. Our results suggest that S. ferax can kill amphibian larvae and further suggest that evaluation of how pathogens affect amphibians at the population level requires investigation at various life stages.
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Affiliation(s)
- John M Romansic
- Department of Zoology, 3029 Cordley Hall, Oregon State University, Corvallis, Oregon 97331, USA.
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Pelizza SA, López Lastra CC, Becnel JJ, Bisaro V, García JJ. Effects of temperature, pH and salinity on the infection of Leptolegnia chapmanii Seymour (Peronosporomycetes) in mosquito larvae. J Invertebr Pathol 2007; 96:133-7. [PMID: 17521667 DOI: 10.1016/j.jip.2007.04.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Revised: 02/26/2007] [Accepted: 04/02/2007] [Indexed: 11/25/2022]
Abstract
The effects of temperature, pH, and NaCl concentrations on the infectivity of zoospores of Leptolegnia chapmanii (Argentine isolate) were determined for Aedes aegypti and Culex pipiens under laboratory conditions. Zoospores of L. chapmanii were infectious at temperatures between 10 and 35 degrees C but not at 5 or 40 degrees C. At the permissive temperatures, mortality rates in young instars were much higher than in older instars and larvae of Ae. aegypti were more susceptible to L. chapmanii than larvae of Cx. pipiens. At 25 degrees C, Ae. aegypti larvae challenged with L. chapmanii zoospores resulted in 100% infection at pH levels ranging from 4 to 10. Larvae of Cx. pipiens exposed to similar pH and zoospore concentrations resulted in increasing mortality rates from 62% to 99% at pH 4 to 7, respectively, and then decreased to 71% at pH 10. Aedes aegypti larvae exposed to L. chapmanii zoospores in NaCl concentrations ranging from 0 to 7 parts per thousand (ppt) at 25 degrees C resulted in 100% mortality while mortality rates for Cx. pipiens decreases from 96% in distilled water to 31.5% in water with 6 ppt NaCl. Control Cx. pipiens larvae died when exposed at a NaCl concentration of 7 ppt. Vegetative growth of L. chapmanii was negatively affected by NaCl concentrations. These results have demonstrated that the Argentinean isolate of L. chapmanii tolerated a wide range of temperatures, pH, and salinity, suggesting that it has the potential to adapt to a wide variety of mosquito habitats.
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Affiliation(s)
- S A Pelizza
- Centro de Estudios Parasitológicos y de Vectores-CEPAVE (UNLP-CONICET), 2 No 584, La Plata, Argentina
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26
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Diéguez-Uribeondo J, Fregeneda-Grandes JM, Cerenius L, Pérez-Iniesta E, Aller-Gancedo JM, Tellería MT, Söderhäll K, Martín MP. Re-evaluation of the enigmatic species complex Saprolegnia diclina–Saprolegnia parasitica based on morphological, physiological and molecular data. Fungal Genet Biol 2007; 44:585-601. [PMID: 17446097 DOI: 10.1016/j.fgb.2007.02.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 02/28/2007] [Accepted: 02/28/2007] [Indexed: 11/28/2022]
Abstract
The phylogenetic relationships among isolates of the Saprolegnia diclina-Saprolegnia parasitica complex were investigated based on ITS rDNA sequences, and correlated with morphological and physiological characters. The isolates studied belong to five phylogenetically separate clades. The majority of presumed parasitic isolates, mostly isolated from fish lesions, fell within a clade that comprises isolates which has been variously named as S. diclina Type 1, S. parasitica, Saprolegnia salmonis or just as unnamed Saprolegnia sp. Presence of bundles of long-hooked hairs on secondary cysts, high frequency of retracted germination, and oogonia production at 7 degrees C (when occurring) were characteristic of this clade. A single isolate identified as S. diclina Type 2 clustered in a clade along with Saprolegnia ferax isolates. The isolates identified as S. diclina s. str. (S. diclina Type 3) distributed in two clades and appeared closely related to Saprolegnia multispora and to a number of Chilean isolates identified as Saprolegnia australis. The ITS sequences of clade I were almost identical even though the isolates were of diverse geographical origins and showed physiological and morphological differences and variations in their pathogenicity. This suggest these species reproduces clonally even in apparently sexually competent isolates. Adaptation to parasitism in Saprolegnia might have occurred at spore level by the development of long-hooked hairs to facilitate host attachment and selection of a retracting germination. The use of the name S. parasitica should be assigned to isolates of clade I that contained isolates forming cysts with bundles of long-hooked hairs.
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Kales SC, DeWitte-Orr SJ, Bols NC, Dixon B. Response of the rainbow trout monocyte/macrophage cell line, RTS11 to the water molds Achlya and Saprolegnia. Mol Immunol 2007; 44:2303-14. [PMID: 17204328 DOI: 10.1016/j.molimm.2006.11.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 10/20/2006] [Accepted: 11/06/2006] [Indexed: 10/23/2022]
Abstract
The Saprolegniales are responsible for various fish mycoses worldwide and considered the most important fungi afflicting fresh water fish. Saprolegniosis leads to massive epidermal destruction and macrophage recruitment, yet little is known regarding the cytological response of their piscine hosts. The objective of this study was to explore the response of fish macrophage to members of the Saprolegniales using the rainbow trout monocyte/macrophage cell line, RTS11. After 48 h in co-culture, RTS11 demonstrated chemotaxis, adherence and homotypic aggregation to both live and heat-killed fungal spores and mycelia. This aggregation was enhanced when using conditioned media from co-cultured RTS11 and Achlya, suggesting the presence of synergistic effectors of aggregation. Although fungal toxins were not evident, as cells remained viable throughout fungal overgrowth, phagocytosis was inhibited due to large fungal spore size, allowing these molds to evade macrophage defenses. Although class I MH and other viral response genes showed no significant change in expression, calreticulin and interleukin-8 were moderately up-regulated implicating calcium modulation and chemotactic response, respectively. Cyclooxygenase (COX-2) and the cytokines IL-1beta and TNFalpha were strongly up-regulated in the presence of Achlya, while gene expression of the class II major histocompatibility (MH II) receptor and associated molecules appeared down-regulated, suggesting fungal interference of immune function. Previous studies have shown an increased dependence of macrophage in immune function at low temperatures; based upon data presented here, this reduction of macrophage MH II receptor expression and inability to phagocytose spores may limit host response thereby providing increased susceptibility to these opportunistic pathogens.
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Affiliation(s)
- Stephen C Kales
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
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Stueland S, Hatai K, Skaar I. Morphological and physiological characteristics of Saprolegnia spp. strains pathogenic to Atlantic salmon, Salmo salar L. J Fish Dis 2005; 28:445-53. [PMID: 16159362 DOI: 10.1111/j.1365-2761.2005.00635.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Seventeen strains of Saprolegnia spp. were examined for morphological and physiological characteristics, and seven were examined for their pathogenicity to Atlantic salmon, Salmo salar L. Two of the Saprolegnia strains tested caused 89 and 31% cumulative mortality in challenged salmonids and were significantly more pathogenic than the other strains tested. The positive control (Saprolegnia parasitica ATCC 90213) caused 18% mortality, but this was not significantly higher than non-pathogenic strains (0-3% cumulative mortality). All the pathogenic Saprolegnia strains and two non-pathogenic strains had secondary cysts with long, hooked hairs, a characteristic which is claimed to be typical of S. parasitica. This characteristic is apparently necessary, but does not in itself determine the ability to cause mortality in Atlantic salmon. However, all the pathogenic Saprolegnia strains in the present study showed a significantly higher initial growth rate of cysts in sterilized tap water than did non-pathogenic strains. The results of the present study suggest that initial growth rate of germinating cysts in pure water, together with the presence of long hooked hairs on the secondary cysts, may be indicators of pathogenicity of Saprolegnia strains to Atlantic salmon.
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Affiliation(s)
- S Stueland
- National Veterinary Institute, Oslo, Norway
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