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Blindheim S, Andersen L, Trösse C, Karlsbakk E, Nylund A. Growth characteristics and morphology of Paramoeba perurans from Atlantic salmon Salmo salar L. and ballan wrasse Labrus bergylta in Norway. Parasit Vectors 2023; 16:112. [PMID: 36959596 PMCID: PMC10037839 DOI: 10.1186/s13071-023-05715-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/22/2023] [Indexed: 03/25/2023] Open
Abstract
BACKGROUND Paramoeba perurans is the causative agent of amoebic gill disease (AGD) in Atlantic salmon Salmo salar L. and many other farmed marine fish species worldwide. The first cases of AGD in Norway were reported in 2006, and it has subsequently become established as a significant gill disease that affects the country's salmonid aquaculture industry. Despite several decades of research on AGD, there is still a lack of knowledge of the biology of P. perurans and its interactions with its hosts and the environment. METHODS The growth and morphology of 10 clonal isolates of P. perurans were studied. The isolates were from farmed Atlantic salmon and ballan wrasse that had been obtained from different sites along the Norwegian coast between 2013 and 2015. The morphology and population growth patterns of these clonal amoeba isolates were examined in vitro using light microscopy and real-time reverse transcription polymerase chain reaction under a range of temperatures (4, 12, 15 and 21 °C) and salinities (20, 25, 30 and 34 ‰). RESULTS We found distinct morphological differences between both locomotive and floating forms of the amoeba isolates. The locomotive amoebae of the clonal isolates varied in size (area) from 453 µm2 to 802 µm2. There were differences in the growth patterns of the clonal amoeba isolates under similar conditions, and in their responses to variations in temperature and salinity. While most of the isolates grew well at salinities of 25-34 ‰, a significant reduction in growth was seen at 20 ‰. Most of the amoeba isolates grew well at 12 °C and 15 °C. At 4 °C, amoebae grew slower and, in contrast to the other temperatures, no extended pseudopodia could be seen in their floating form. The isolates seemed to reach a plateau phase faster at 21 °C, with a higher number of smaller, rounded amoebae. CONCLUSIONS The differences observed here between clonal isolates of P. perurans should be further examined in experimental in vivo challenge studies, as they may be of relevance to the virulence and proliferation potential of this amoeba on gills. Potential differences in virulence within P. perurans could have implications for management strategies for AGD.
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Affiliation(s)
- Steffen Blindheim
- Department of Biological Sciences, University of Bergen, 7803, 5020, Bergen, Norway
- The Industrial and Aquatic Laboratory, Thormøhlensgate 55, 5006, Bergen, Norway
| | - Linda Andersen
- The Industrial and Aquatic Laboratory, Thormøhlensgate 55, 5006, Bergen, Norway.
| | - Christiane Trösse
- Department of Biological Sciences, University of Bergen, 7803, 5020, Bergen, Norway
| | - Egil Karlsbakk
- Department of Biological Sciences, University of Bergen, 7803, 5020, Bergen, Norway
| | - Are Nylund
- Department of Biological Sciences, University of Bergen, 7803, 5020, Bergen, Norway
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Osmotic Gradient Is a Factor That Influences the Gill Microbiota Communities in Oryzias melastigma. BIOLOGY 2022; 11:biology11101528. [PMID: 36290431 PMCID: PMC9598346 DOI: 10.3390/biology11101528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/11/2022] [Accepted: 10/13/2022] [Indexed: 11/05/2022]
Abstract
Simple Summary This study was applied to the laboratory medaka to understand how the osmotic gradient could influence the composition of the gill microbiota communities. The data suggested that the shift of the gill microbiota community has relied on the first sense of osmolality differences, and such changes were accomplished by the enriched osmosensing and metabolic pathways. Abstract The fish gill is the first tissue that is exposed to the external media and undergoes continuous osmotic challenges. Recently, our group published an article entitled “Integrated Omics Approaches Revealed the Osmotic Stress-Responsive Genes and Microbiota in Gill of Marine Medaka” in the journal mSystems (e0004722, 2022), and suggested the possible host-bacterium interaction in the fish gill during osmotic stress. The previous study was performed by the progressive fresh water transfer (i.e., seawater to fresh water transfer via 50% seawater (FW)). Our group hypothesized that osmotic gradient could be a factor that determines the microbiota communities in the gill. The current 16S rRNA metagenomic sequencing study found that the direct transfer (i.e., seawater to fresh water (FWd)) could result in different gill microbiota communities in the same fresh water endpoints. Pseduomonas was the dominant bacteria (more than 55%) in the FWd gill. The Kyoto Encyclopedia of Genes and Genomes and MetaCyc analysis further suggested that the FWd group had enhanced osmosensing pathways, such as the ATP-binding cassette transporters, taurine degradation, and energy-related tricarboxylic acid metabolism compared to the FW group.
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Jellyfish as Food: A Narrative Review. Foods 2022; 11:foods11182773. [PMID: 36140901 PMCID: PMC9498191 DOI: 10.3390/foods11182773] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 09/03/2022] [Accepted: 09/06/2022] [Indexed: 11/28/2022] Open
Abstract
Studies toward a sustainable future conducted by international organizations uniformly agree about having to change some of our present consumer behaviors. Regarding food, suggestions include eating locally farmed, less industrialized and renewable food to promote health and circularity, and limiting waste. Jellyfish are frequently sorted and discarded after being caught with fish in fishing nets and gear. In contrast, we propose utilizing this by-catch as food. This review discusses the economic value and sustainability of jellyfish, the technologies used to prepare them for human consumption, their nutritional profile and health impacts and, finally, consumer acceptability and sensory evaluation of jellyfish food products. This discussion is critical for promoting jellyfish as an important aquatic resource to support blue and circular economies.
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Fernandez-Senac C, Monaghan SJ, Mascolo D, Baily JL, Betancor M, Chalmers L, Paladini G, Adams A, Fridman S, Bron JE. Investigating the impacts of H 2O 2 treatment on gills of healthy Atlantic salmon reveals potential changes to mucus production with implications on immune activity. FISH & SHELLFISH IMMUNOLOGY 2022; 128:74-81. [PMID: 35843527 DOI: 10.1016/j.fsi.2022.06.063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 06/21/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Current treatment strategies for relevant infectious diseases in Atlantic salmon (Salmo salar L.) include the use of low salinity or freshwater bathing. However, often availability is restricted, and hydrogen peroxide (H2O2) is used as an alternative. The potential impacts of H2O2 on fish mucosal tissues, especially the gills therefore need to be considered. In this study the mucosal and immunological effects of H2O2 treatment on the gills of healthy Atlantic salmon were examined by gene expression (qPCR) and immunohistochemistry (IHC) investigating T-cell, B-cell, and mucin activity. Healthy fish were treated with H2O2 and sampled at different times: 4 h, 24 h and 14 days post-H2O2 treatment (dpt) (total n = 18) to investigate the effect of holding time and H2O2 treatment. Treatment with H2O2 resulted in up-regulation of markers for T-cell activity and anti-inflammatory response and down-regulation of mucin expression in the gills at 14 dpt compared to fish sampled prior to treatment (0h; n = 5 fish). These findings were supported by IHC analysis, which despite being highly variable between samples, showed an increase in the number of CD3+ T cells at 14 dpt in 50% of treated fish compared to pre-treatment fish. The results from this study suggest that H2O2 treatment does not immune compromise healthy Atlantic salmon after 14 dpt (i.e., post-recovery) but modulates gill immune activity and disrupts the mucus covering of the gills. However, further studies are required to determine whether the effects observed are related to H2O2 treatment in isolation or other variables such as holding time or environmental factors.
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Affiliation(s)
| | - Sean J Monaghan
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
| | - Dario Mascolo
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
| | - Johanna L Baily
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
| | - Monica Betancor
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
| | - Lynn Chalmers
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
| | - Giuseppe Paladini
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
| | - Alexandra Adams
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
| | - Sophie Fridman
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
| | - James E Bron
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
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Østevik L, Stormoen M, Hellberg H, Kraugerud M, Manji F, Lie K, Nødtvedt A, Rodger H, Alarcón M. A cohort study of gill infections, gill pathology and gill-related mortality in sea-farmed Atlantic salmon (Salmo salar L.): A descriptive analysis. JOURNAL OF FISH DISEASES 2022; 45:1301-1321. [PMID: 35707921 PMCID: PMC9543555 DOI: 10.1111/jfd.13662] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 05/30/2023]
Abstract
Gill disease is an important cause of economic losses, fish mortality and reduced animal welfare in salmonid farming. We performed a prospective cohort study, following groups of Atlantic salmon in Western Norway with repeated sampling and data collection from the hatchery phase and throughout the 1st year at sea. The objective was to determine if variation in pathogen prevalence and load, and zoo- and phytoplankton levels had an impact on gill health. Further to describe the temporal development of pathogen prevalence and load, and gill pathology, and how these relate to each other. Neoparamoeba perurans appeared to be the most important cause of gill pathology. No consistent covariation and no or weak associations between the extent of gill pathology and prevalence and load of SGPV, Ca. B. cysticola and D. lepeophtherii were observed. At sea, D. lepeophtherii and Ca. B. cysticola persistently infected all fish groups. Fish groups negative for SGPV at sea transfer were infected at sea and fish groups tested negative before again testing positive. This is suggestive of horizontal transmission of infection at sea and may indicate that previous SGPV infection does not protect against reinfection. Coinfections with three or more putative gill pathogens were found in all fish groups and appear to be the norm in sea-farmed Atlantic salmon in Western Norway.
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Affiliation(s)
| | - Marit Stormoen
- Department of Production Animal Clinical Sciences, Faculty of Veterinary MedicineNorwegian University of Life SciencesÅsNorway
| | | | | | | | | | - Ane Nødtvedt
- Department of Production Animal Clinical Sciences, Faculty of Veterinary MedicineNorwegian University of Life SciencesÅsNorway
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Prospective Longitudinal Study of Putative Agents Involved in Complex Gill Disorder in Atlantic salmon ( Salmo salar). Pathogens 2022; 11:pathogens11080878. [PMID: 36014998 PMCID: PMC9415954 DOI: 10.3390/pathogens11080878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/11/2022] [Accepted: 07/28/2022] [Indexed: 01/27/2023] Open
Abstract
Complex gill disorder (CGD) is an important condition in Atlantic salmon aquaculture, but the roles of the putative aetiological agents in the pathogenesis are uncertain. A longitudinal study was undertaken on two salmon farms in Scotland to determine the variations in loads of CGD-associated pathogens (Desmozoon lepeophtherii, Candidatus Branchiomonas cysticola, salmon gill pox virus (SGPV) and Neoparamoeba perurans) estimated by quantitative PCR. In freshwater, Ca. B. cysticola and SGPV were detected in both populations, but all four pathogens were detected on both farms during the marine stage. Candidatus B. cysticola and D. lepeophtherii were detected frequently, with SGPV detected sporadically. In the marine phase, increased N. perurans loads associated significantly (p < 0.05) with increases in semi-quantitative histological gill-score (HGS). Increased Ca. B. cysticola load associated significantly (p < 0.05) with increased HGS when only Farm B was analysed. Higher loads of D. lepeophtherii were associated significantly (p < 0.05) with increased HGS on Farm B despite the absence of D. lepeophtherii-type microvesicles. Variations in SGPV were not associated significantly (p > 0.05) with changes in HSG. This study also showed that water temperature (season) and certain management factors were associated with higher HGS. This increase in histological gill lesions will have a deleterious impact on fish health and welfare, and production performance.
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Mocho JP, Collymore C, Farmer SC, Leguay E, Murray KN, Pereira N. FELASA-AALAS Recommendations for Monitoring and Reporting of Laboratory Fish Diseases and Health Status, with an Emphasis on Zebrafish ( Danio Rerio). Comp Med 2022; 72:127-148. [PMID: 35513000 PMCID: PMC9334007 DOI: 10.30802/aalas-cm-22-000034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/02/2022] [Indexed: 11/05/2022]
Abstract
The exchange of fish for research may expose an aquatic laboratory to pathogen contamination as incoming fish can introduce bacteria, fungi, parasites, and viruses capable of affecting both experimental results and fish and personnel health and welfare. To develop risk mitigation strategies, FELASA and AALAS established a joint working group to recommend good practices for health monitoring of laboratory fish. The recommendations address all fish species used for research, with a particular focus on zebrafish (Danio rerio). First, the background of the working group and key definitions are provided. Next, fish diseases of high impact are described. Third, recommendations are made for health monitoring of laboratory fishes. The recommendations emphasize the importance of daily observation of the fish and strategies to determine fish colony health status. Finally, report templates are proposed for historical screening data and aquatic facility description to facilitate biohazard risk assessment when exchanging fish.
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Affiliation(s)
| | - Chereen Collymore
- Veterinary Care and Services, Charles River Laboratories, Senneville, Quebec, Canada
| | - Susan C Farmer
- Zebrafish Research Facility, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | | - Katrina N Murray
- Zebrafish International Resource Center, University of Oregon, Eugene, Oregon, USA
| | - Nuno Pereira
- Chronic Diseases Research Center (CEDOC), Nova Medical School, Lisbon; Faculty of Veterinary Medicine, Lusophone University of Humanities and Technologies, Lisbon, Portugal; Gulbenkian Institute of Science, Oeiras. Portugal; ISPA - University Institute of Psychological, Social and Life Sciences, Lisbon, Portugal; Lisbon Oceanarium, Lisbon, Portugal
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8
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Emam M, Caballero-Solares A, Xue X, Umasuthan N, Milligan B, Taylor RG, Balder R, Rise ML. Gill and Liver Transcript Expression Changes Associated With Gill Damage in Atlantic Salmon ( Salmo salar). Front Immunol 2022; 13:806484. [PMID: 35418993 PMCID: PMC8996064 DOI: 10.3389/fimmu.2022.806484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/31/2022] [Indexed: 12/24/2022] Open
Abstract
Gill damage represents a significant challenge in the teleost fish aquaculture industry globally, due to the gill’s involvement in several vital functions and direct contact with the surrounding environment. To examine the local and systemic effects accompanying gill damage (which is likely to negatively affect gill function) of Atlantic salmon, we performed a field sampling to collect gill and liver tissue after several environmental insults (e.g., harmful algal blooms). Before sampling, gills were visually inspected and gill damage was scored; gill scores were assigned from pristine [gill score 0 (GS0)] to severely damaged gills (GS3). Using a 44K salmonid microarray platform, we aimed to compare the transcriptomes of pristine and moderately damaged (i.e., GS2) gill tissue. Rank Products analysis (5% percentage of false-positives) identified 254 and 34 upregulated and downregulated probes, respectively, in GS2 compared with GS0. Differentially expressed probes represented genes associated with functions including gill remodeling, wound healing, and stress and immune responses. We performed gill and liver qPCR for all four gill damage scores using microarray-identified and other damage-associated biomarker genes. Transcripts related to wound healing (e.g., neb and klhl41b) were significantly upregulated in GS2 compared with GS0 in the gills. Also, transcripts associated with immune and stress-relevant pathways were dysregulated (e.g., downregulation of snaclec 1-like and upregulation of igkv3) in GS2 compared with GS0 gills. The livers of salmon with moderate gill damage (i.e., GS2) showed significant upregulation of transcripts related to wound healing (i.e., chtop), apoptosis (e.g., bnip3l), blood coagulation (e.g., f2 and serpind1b), transcription regulation (i.e., pparg), and stress-responses (e.g., cyp3a27) compared with livers of GS0 fish. We performed principal component analysis (PCA) using transcript levels for gill and liver separately. The gill PCA showed that PC1 significantly separated GS2 from all other gill scores. The genes contributing most to this separation were pgam2, des, neb, tnnt2, and myom1. The liver PCA showed that PC1 significantly separated GS2 from GS0; levels of hsp70, cyp3a27, pparg, chtop, and serpind1b were the highest contributors to this separation. Also, hepatic acute phase biomarkers (e.g., serpind1b and f2) were positively correlated to each other and to gill damage. Gill damage-responsive biomarker genes and associated qPCR assays arising from this study will be valuable in future research aimed at developing therapeutic diets to improve farmed salmon welfare.
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Affiliation(s)
- Mohamed Emam
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | | | - Xi Xue
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | | | | | - Richard G Taylor
- Cargill Animal Nutrition and Health, Elk River, MN, United States
| | - Rachel Balder
- Cargill Animal Nutrition and Health, Elk River, MN, United States
| | - Matthew L Rise
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
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Boerlage AS, Ashby A, Eze J, Gunn G, Reeves A. Field evaluation of diagnostic sensitivity (DSe) and specificity (DSp) of common tests for amoebic gill disease (AGD) and complex gill disease (CGD) in cultured Atlantic salmon (Salmo salar) in Scotland using Bayesian latent class models. Prev Vet Med 2022; 204:105654. [DOI: 10.1016/j.prevetmed.2022.105654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/15/2022] [Accepted: 04/18/2022] [Indexed: 11/25/2022]
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10
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Integrated Omics Approaches Revealed the Osmotic Stress-Responsive Genes and Microbiota in Gill of Marine Medaka. mSystems 2022; 7:e0004722. [PMID: 35285678 PMCID: PMC9040874 DOI: 10.1128/msystems.00047-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This is the first study using the transcriptome and 16S rRNA gene sequencing to report the hypotonic responsive genes in gill cells and the compositions of gill microbiota in marine medaka. The overlapped glycosaminoglycan- and chitin-related pathways suggest host-bacterium interaction in fish gill during osmotic stress.
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Fridman S, Tsairidou S, Jayasuriya N, Sobolewska H, Hamilton A, Lobos C, Houston RD, Rodger H, Bron J, Herath T. Assessment of Marine Gill Disease in Farmed Atlantic Salmon ( Salmo salar) in Chile Using a Novel Total Gross Gill Scoring System: A Case Study. Microorganisms 2021; 9:microorganisms9122605. [PMID: 34946205 PMCID: PMC8706402 DOI: 10.3390/microorganisms9122605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 11/16/2022] Open
Abstract
Gill disorders have become more prevalent and widespread in finfish aquaculture in recent years. Their aetiology is often considered to be multifactorial. Effective diagnosis, control and prevention are hindered by the lack of standardised methodologies to characterise the aetiological agents, which produce an array of clinical and pathological presentations. The aim of this study was to define a novel gross pathological scoring system suitable for field-based macroscopic assessment of complex or multifactorial gill disease in farmed Atlantic salmon, using samples derived from a gill disease outbreak in Chile. Clinical assessment of gross gill morphology was performed, and gill samples were collected for qPCR and histology. A novel total gill scoring system was developed, which assesses gross pathological changes combining both the presumptive or healed amoebic gill disease (AGD) and the presence of other types of gill lesions. This scoring system offers a standardised approach to characterise the severe proliferative pathologies in affected gills. This total gill scoring system can substantially contribute to the development of robust mitigation strategies and could be used as an indicator trait for incorporating resistance to multifactorial gill disease into breeding goals.
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Affiliation(s)
- Sophie Fridman
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK;
- Correspondence:
| | - Smaragda Tsairidou
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH25 9RG, UK; (S.T.); (R.D.H.)
| | - Nilantha Jayasuriya
- Department of Animal Health, Behaviour and Welfare, Harper Adams University, Newport TF10 8NB, Shropshire, UK; (N.J.); (T.H.)
| | | | - Alastair Hamilton
- Hendrix Genetics, Villa ’de Körver’, Boxmeer, 695831 CK Spoorstraat, The Netherlands; (A.H.); (C.L.)
| | - Carlos Lobos
- Hendrix Genetics, Villa ’de Körver’, Boxmeer, 695831 CK Spoorstraat, The Netherlands; (A.H.); (C.L.)
- PHARMAQ Analytiq Spa, Bernardino, Puerto Montt 1978, Chile
| | - Ross D. Houston
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH25 9RG, UK; (S.T.); (R.D.H.)
| | | | - James Bron
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK;
| | - Tharangani Herath
- Department of Animal Health, Behaviour and Welfare, Harper Adams University, Newport TF10 8NB, Shropshire, UK; (N.J.); (T.H.)
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Slinger J, Wynne JW, Adams MB. Profiling Branchial Bacteria of Atlantic Salmon (Salmo salar L.) Following Exposure to Antimicrobial Agents. FRONTIERS IN ANIMAL SCIENCE 2021. [DOI: 10.3389/fanim.2021.756101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Microbial gill diseases caused by either opportunistic or specific pathogens are an emerging area of concern for aquaculture producers in part due to their sometimes complex and/or cryptic nature. Many antimicrobial treatments used in aquacultural settings are broad spectrum in nature. The effect of such therapeutics upon reduction and recolonization of commensal or pathogenic microbiota post-treatment has received little attention to date. Commensal bacteria are an integral component of the barrier function of mucosal surfaces in animals. This study evaluated the effect of several commercially relevant antimicrobial treatments upon the diversity and composition of branchial bacteria of Atlantic salmon. Here we exposed Atlantic salmon smolt to a number of commercially relevant antimicrobial treatments including chemotherapeutants (chloramine-t and hydrogen peroxide) and antibiotics (oxytetracycline and florfenicol) in vivo. Subsequently we examined the change in bacterial load, 16S rRNA gene expression, and taxonomic diversity post-treatment upon the gills. Results revealed a decrease in cultivable bacterial colonies after antimicrobial treatment, and a downstream decrease in bacterial richness and abundance post-treatment, with colonization of several prominent pathogenic taxa including Vibrio and Tenacibaculum. Temporal tracing over a 14-day period demonstrated that the bacteriome of gill mucus is sensitive to change, and altered by antimicrobial treatment and handling. This study identified candidate antimicrobial treatments which could be implemented in future studies to illustrate the effect of dysbiosis on microbial gill diseases.
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13
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Lima PC, Hartley-Tassell L, Wynne JW. The ability of Neoparamoeba perurans to bind to and digest non-fish-derived mucin: Insights into the amoeba's mechanism of action to overcome gill mucus production. JOURNAL OF FISH DISEASES 2021; 44:1355-1367. [PMID: 33990985 DOI: 10.1111/jfd.13394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 06/12/2023]
Abstract
Amoebic gill disease (AGD) is caused by the marine amoeba Neoparamoeba perurans, a facultative parasite. Despite the significant impact this disease has on production of Atlantic salmon worldwide, the mechanisms involved in host-parasite interaction remains unknown. Excessive gill mucus secretion is reported as a host defence mechanism to prevent microbial colonization in the gill epithelium. Despite this response, N. perurans still attaches and proliferates. The present study aimed to investigate the interaction between N. perurans and mucin, the most abundant component in mucus. An in vitro adhesion assay using bovine submaxillary mucin (BSM) demonstrated that amoeba binding to mucin-coated substrate was significantly higher than to the BSA control. This binding interaction is likely glycan-mediated as pre-incubation with galactose, galactosamine, N-acetylgalactosamine and fucose reduced mucin adhesion to control levels. The ability of N. perurans to secrete proteases that target mucin was also investigated. Protease activity was detected in the amoeba culture media in the presence of BSM, but not when protease inhibitor was added. Mucin degradation was visually assessed on protein gels. This study provides preliminary evidence that N. perurans has developed mechanisms to interact with and evade mucus by binding to mucin glycan receptors and secreting proteases with mucolytic activity.
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Affiliation(s)
- Paula C Lima
- CSIRO Livestock & Aquaculture Program, Queensland, Australia
| | | | - James W Wynne
- CSIRO Livestock & Aquaculture Program, Tasmania, Australia
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14
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Conforto E, Vílchez-Gómez L, Parrinello D, Parisi MG, Esteban MÁ, Cammarata M, Guardiola FA. Role of mucosal immune response and histopathological study in European eel (Anguilla anguilla L.) intraperitoneal challenged by Vibrio anguillarum or Tenacibaculum soleae. FISH & SHELLFISH IMMUNOLOGY 2021; 114:330-339. [PMID: 34015481 DOI: 10.1016/j.fsi.2021.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 05/07/2021] [Accepted: 05/12/2021] [Indexed: 06/12/2023]
Abstract
The external mucus layer that covers fish skin contains numerous immune substances scarcely studied that act as the first line of defence against a broad spectrum of pathogens. This study aimed to characterize and describe for the first time several humoral immune defence parameters in the skin mucus of the European eel (Anguilla anguilla) after intraperitoneal injection with Vibrio anguillarum or Tenacibaculum soleae. This study evaluated several immune-related enzymes and bactericidal activity against fish pathogenic bacteria in the skin mucus of European eels at 24, 48, and 72 h post-challenge. The results demonstrated that European eel skin mucus showed significant increments in peroxidase and lysozyme activity at 48 and 72 h after V. anguillarum challenge, compared to other experimental groups. In the case of antiprotease activity, an increase was observed at 24 h in the skin mucus of fish challenged with V. anguillarum compared to unchallenged fish, while this activity was undetected at 48 and 72 h. In contrast, protease activity had decreased at 48 and 72 h in the skin mucus of fish challenged with V. anguillarum compared to the unchallenged group. Regarding bactericidal activity, a high growth capacity of T. soleae was observed in the skin mucus of all experimental groups. Interestingly, the skin mucus from fish challenged with V. anguillarum exhibited increased bactericidal activity against this bacterium at 48 h, compared to unchallenged fish. Finally, severe histopathological alterations were observed in the gills and liver at the end of the trial (72 h), whereas the skin showed only an overspread presence of goblet cells in the challenged fish compared to unchallenged fish. The present results may give new insights into the mucosal immune system of this primitive species with potential applications in aquaculture.
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Affiliation(s)
- Emanuele Conforto
- Marine Immunobiology Laboratory, Department of Earth and Marine Sciences, University of Palermo, Viale delle Scienze, Ed.16, 90128, Palermo, Italy
| | - Luciano Vílchez-Gómez
- Department of Cellular Biology and Histology, Faculty of Biology, University of Murcia, Campus of International Excellence, Campus Mare Nostrum, 30100, Murcia, Spain
| | - Daniela Parrinello
- Marine Immunobiology Laboratory, Department of Earth and Marine Sciences, University of Palermo, Viale delle Scienze, Ed.16, 90128, Palermo, Italy
| | - Maria Giovanna Parisi
- Marine Immunobiology Laboratory, Department of Earth and Marine Sciences, University of Palermo, Viale delle Scienze, Ed.16, 90128, Palermo, Italy
| | - María Ángeles Esteban
- Department of Cellular Biology and Histology, Faculty of Biology, University of Murcia, Campus of International Excellence, Campus Mare Nostrum, 30100, Murcia, Spain
| | - Matteo Cammarata
- Marine Immunobiology Laboratory, Department of Earth and Marine Sciences, University of Palermo, Viale delle Scienze, Ed.16, 90128, Palermo, Italy.
| | - Francisco A Guardiola
- Department of Cellular Biology and Histology, Faculty of Biology, University of Murcia, Campus of International Excellence, Campus Mare Nostrum, 30100, Murcia, Spain; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Porto, Portugal.
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15
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Comparative proteomic profiling of newly acquired, virulent and attenuated Neoparamoeba perurans proteins associated with amoebic gill disease. Sci Rep 2021; 11:6830. [PMID: 33767232 PMCID: PMC7994405 DOI: 10.1038/s41598-021-85988-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/02/2021] [Indexed: 12/25/2022] Open
Abstract
The causative agent of amoebic gill disease, Neoparamoeba perurans is reported to lose virulence during prolonged in vitro maintenance. In this study, the impact of prolonged culture on N. perurans virulence and its proteome was investigated. Two isolates, attenuated and virulent, had their virulence assessed in an experimental trial using Atlantic salmon smolts and their bacterial community composition was evaluated by 16S rRNA Illumina MiSeq sequencing. Soluble proteins were isolated from three isolates: a newly acquired, virulent and attenuated N. perurans culture. Proteins were analysed using two-dimensional electrophoresis coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). The challenge trial using naïve smolts confirmed a loss in virulence in the attenuated N. perurans culture. A greater diversity of bacterial communities was found in the microbiome of the virulent isolate in contrast to a reduction in microbial community richness in the attenuated microbiome. A collated proteome database of N. perurans, Amoebozoa and four bacterial genera resulted in 24 proteins differentially expressed between the three cultures. The present LC-MS/MS results indicate protein synthesis, oxidative stress and immunomodulation are upregulated in a newly acquired N. perurans culture and future studies may exploit these protein identifications for therapeutic purposes in infected farmed fish.
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16
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Lima PC, Hartley-Tassell L, Cooper O, Wynne JW. Searching for the sweet spot of amoebic gill disease of farmed Atlantic salmon: the potential role of glycan-lectin interactions in the adhesion of Neoparamoeba perurans. Int J Parasitol 2021; 51:545-557. [PMID: 33675796 DOI: 10.1016/j.ijpara.2020.11.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/04/2020] [Accepted: 11/15/2020] [Indexed: 01/25/2023]
Abstract
One of the first critical steps in the pathogenesis of amoebic gill disease (AGD) of farmed salmon is the adhesion of the causative amoeba to the host. The current study aimed to investigate the potential involvement of glycan-binding proteins expressed on the extracellular surface of Neoparamoeba perurans in gill tissue recognition and binding. The glycan-binding properties of the surface membrane of N. perurans and the carbohydrate binding profile of Atlantic salmon gill-derived epithelial cells were identified through the use of glycan and lectin microarrays, respectively. The occurrence of specific carbohydrate-mediated binding was then further assessed by in vitro attachment assays using microtitre plates pre-coated with the main glycan candidates. Adhesion assays were also performed in the presence of exogenous saccharides with the aim of blocking glycan-specific binding activity. Comparative analysis of the results from both lectin and glycan arrays showed significant overlap, as some glycans to which binding by the amoeba was seen were reflected as being present on the gill epithelial cells. The two main candidates proposed to be involved in amoeba attachment to the gills are mannobiose and N-acetylgalactosamine (GalNAc). Adhesion of amoebae significantly increased by 33.5 and 23% when cells were added to α1,3-Mannobiose-BSA and GalNAc-BSA coated plates. The observed increased in attachment was significantly reduced when the amoebae were incubated with exogenous glycans, further demonstrating the presence of mannobiose- and GalNAc-binding sites on the surfaces of the cells. We believe this study provides the first evidence for the presence of a highly specific carbohydrate recognition and binding system in N. perurans. These preliminary findings could be of extreme importance given that AGD is an external parasitic infestation and much of the current research on the development of alternative treatment strategies relies on either instant amoeba detachment or blocking parasite attachment.
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Affiliation(s)
- P C Lima
- CSIRO Agriculture and Food, Livestock & Aquaculture, Queensland Biosciences Precinct, 306 Carmody Road, Brisbane, QLD 4067, Australia.
| | - L Hartley-Tassell
- Institute for Glycomics, Griffith University, Gold Coast Campus, Gold Coast, QLD 4222, Australia
| | - O Cooper
- Institute for Glycomics, Griffith University, Gold Coast Campus, Gold Coast, QLD 4222, Australia
| | - J W Wynne
- CSIRO Agriculture and Food, Livestock & Aquaculture, Castray Esplanade, Battery Point, TAS 7004, Australia
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17
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English CJ, Lima PC. Defining the aetiology of amoebic diseases of aquatic animals: trends, hurdles and best practices. DISEASES OF AQUATIC ORGANISMS 2020; 142:125-143. [PMID: 33269724 DOI: 10.3354/dao03537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Disease caused by parasitic amoebae impacts a range of aquatic organisms including finfish, crustaceans, echinoderms and molluscs. Despite the significant economic impact caused in both aquaculture and fisheries, the aetiology of most aquatic amoebic diseases is uncertain, which then affects diagnosis, treatment and prevention. The main factors hampering research effort in this area are the confusion around amoeba taxonomy and the difficulty proving that a particular species causes specific lesions. These issues stem from morphological and genetic similarities between cryptic species and technical challenges such as establishing and maintaining pure amoeba cultures, scarcity of Amoebozoa sequence data, and the inability to trigger pathogenesis under experimental conditions. This review provides a critical analysis of how amoebae are commonly identified and defined as aetiological agents of disease in aquatic animals and highlights gaps in the available knowledge regarding determining pathogenic Amoebozoa.
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Affiliation(s)
- Chloe J English
- CSIRO Agriculture and Food, Livestock and Aquaculture, Queensland Bioscience Precinct, St. Lucia, QLD 4067, Australia
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18
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Alix M, Gasset E, Bardon-Albaret A, Noel J, Pirot N, Perez V, Coves D, Saulnier D, Lignot JH, Cucchi PN. Description of the unusual digestive tract of Platax orbicularis and the potential impact of Tenacibaculum maritimum infection. PeerJ 2020; 8:e9966. [PMID: 33024633 PMCID: PMC7520087 DOI: 10.7717/peerj.9966] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/26/2020] [Indexed: 12/11/2022] Open
Abstract
Background Ephippidae fish are characterized by a discoid shape with a very small visceral cavity. Among them Platax orbicularis has a high economic potential due to its flesh quality and flesh to carcass ratio. Nonetheless, the development of its aquaculture is limited by high mortality rates, especially due to Tenacibaculum maritimum infection, occurring one to three weeks after the transfer of fishes from bio-secure land-based aquaculture system to the lagoon cages for growth. Among the lines of defense against this microbial infection, the gastrointestinal tract (GIT) is less studied. The knowledge about the morphofunctional anatomy of this organ in P. orbicularis is still scarce. Therefore, the aims of this study are to characterize the GIT in non-infected P. orbicularis juveniles to then investigate the impact of T. maritimum on this multifunctional organ. Methods In the first place, the morpho-anatomy of the GIT in non-infected individuals was characterized using various histological techniques. Then, infected individuals, experimentally challenged by T. maritimum were analysed and compared to the previously established GIT reference. Results The overlapped shape of the GIT of P. orbicularis is probably due to its constrained compaction in a narrow visceral cavity. Firstly, the GIT was divided into 10 sections, from the esophagus to the rectum. For each section, the structure of the walls was characterized, with a focus on mucus secretions and the presence of the Na+/K+ ATPase pump. An identification key allowing the characterization of the GIT sections using in toto histology is given. Secondly, individuals challenged with T. maritimum exhibited differences in mucus type and proportion and, modifications in the mucosal and muscle layers. These changes could induce an imbalance in the trade-off between the GIT functions which may be in favour of protection and immunity to the disadvantage of nutrition capacities.
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Affiliation(s)
- Maud Alix
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France.,Institute of Marine Research, Bergen, Norway
| | - Eric Gasset
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Agnes Bardon-Albaret
- Ifremer, UMR Ecosystèmes Insulaires Océaniens, UPF, ILM, IRD, Tahiti, French Polynesia
| | - Jean Noel
- BCM, Université de Montpellier, CNRS, INSERM, Montpellier, France.,IRCM, Université de Montpellier, ICM, INSERM, Montpellier, France
| | - Nelly Pirot
- BCM, Université de Montpellier, CNRS, INSERM, Montpellier, France.,IRCM, Université de Montpellier, ICM, INSERM, Montpellier, France
| | - Valérie Perez
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Denis Coves
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Denis Saulnier
- Ifremer, UMR Ecosystèmes Insulaires Océaniens, UPF, ILM, IRD, Tahiti, French Polynesia
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19
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Oldham T, Dempster T, Crosbie P, Adams M, Nowak B. Cyclic Hypoxia Exposure Accelerates the Progression of Amoebic Gill Disease. Pathogens 2020; 9:pathogens9080597. [PMID: 32707755 PMCID: PMC7460382 DOI: 10.3390/pathogens9080597] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/15/2020] [Accepted: 07/20/2020] [Indexed: 12/23/2022] Open
Abstract
Amoebic gill disease (AGD), caused by the amoeba Neoparamoeba perurans, has led to considerable economic losses in every major Atlantic salmon producing country, and is increasing in frequency. The most serious infections occur during summer and autumn, when temperatures are high and poor dissolved oxygen (DO) conditions are most common. Here, we tested if exposure to cyclic hypoxia at DO saturations of 40–60% altered the course of infection with N. perurans compared to normoxic controls maintained at ≥90% DO saturation. Although hypoxia exposure did not increase initial susceptibility to N. perurans, it accelerated progression of the disease. By 7 days post-inoculation, amoeba counts estimated from qPCR analysis were 1.7 times higher in the hypoxic treatment than in normoxic controls, and cumulative mortalities were twice as high (16 ± 4% and 8 ± 2%), respectively. At 10 days post-inoculation, however, there were no differences between amoeba counts in the hypoxic and normoxic treatments, nor in the percentage of filaments with AGD lesions (control = 74 ± 2.8%, hypoxic = 69 ± 3.3%), or number of lamellae per lesion (control = 30 ± 0.9%, hypoxic = 27.9 ± 0.9%) as determined by histological examination. Cumulative mortalities at the termination of the experiment were similarly high in both treatments (hypoxic = 60 ± 2%, normoxic = 53 ± 11%). These results reveal that exposure to cyclic hypoxia in a diel pattern, equivalent to what salmon are exposed to in marine aquaculture cages, accelerated the progression of AGD in post-smolts.
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Affiliation(s)
- Tina Oldham
- Institute of Marine Research, 5984 Matre, Norway
- Aquatic Animal Health Group, Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7248, Australia; (P.C.); (M.A.); (B.N.)
- Correspondence:
| | - Tim Dempster
- Sustainable Aquaculture Laboratory–Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Parkville, VIC 3010, Australia;
| | - Philip Crosbie
- Aquatic Animal Health Group, Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7248, Australia; (P.C.); (M.A.); (B.N.)
| | - Mark Adams
- Aquatic Animal Health Group, Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7248, Australia; (P.C.); (M.A.); (B.N.)
| | - Barbara Nowak
- Aquatic Animal Health Group, Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7248, Australia; (P.C.); (M.A.); (B.N.)
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20
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Marcos‐López M, Rodger HD. Amoebic gill disease and host response in Atlantic salmon (
Salmo salar
L.): A review. Parasite Immunol 2020; 42:e12766. [DOI: 10.1111/pim.12766] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 04/13/2020] [Accepted: 06/16/2020] [Indexed: 12/16/2022]
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21
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Król E, Noguera P, Shaw S, Costelloe E, Gajardo K, Valdenegro V, Bickerdike R, Douglas A, Martin SAM. Integration of Transcriptome, Gross Morphology and Histopathology in the Gill of Sea Farmed Atlantic Salmon ( Salmo salar): Lessons From Multi-Site Sampling. Front Genet 2020; 11:610. [PMID: 32636874 PMCID: PMC7316992 DOI: 10.3389/fgene.2020.00610] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 05/19/2020] [Indexed: 12/11/2022] Open
Abstract
The gill of teleost fish is a multifunctional organ involved in many physiological processes such as gas exchange, osmotic and ionic regulation, acid-base balance and excretion of nitrogenous waste. Due to its extensive interface with the environment, the gill plays a key role as a primary mucosal defense tissue against pathogens, as manifested by the presence of the gill-associated lymphoid tissue (GIALT). In recent years, the prevalence of multifactorial gill pathologies has increased significantly, causing substantial losses in Atlantic salmon aquaculture. The transition from healthy to unhealthy gill phenotypes and the progression of multifactorial gill pathologies, such as proliferative gill disease (PGD), proliferative gill inflammation (PGI) and complex gill disorder (CGD), are commonly characterized by epithelial hyperplasia, lamellar fusion and inflammation. Routine monitoring for PGD relies on visual inspection and non-invasive scoring of the gill tissue (gross morphology), coupled with histopathological examination of gill sections. To explore the underlying molecular events that are associated with the progression of PGD, we sampled Atlantic salmon from three different marine production sites in Scotland and examined the gill tissue at three different levels of organization: gross morphology with the use of PGD scores (macroscopic examination), whole transcriptome (gene expression by RNA-seq) and histopathology (microscopic examination). Our results strongly suggested that the changes in PGD scores of the gill tissue were not associated with the changes in gene expression or histopathology. In contrast, integration of the gill RNA-seq data with the gill histopathology enabled us to identify common gene expression patterns associated with multifactorial gill disease, independently from the origin of samples. We demonstrated that the gene expression patterns associated with multifactorial gill disease were dominated by two processes: a range of immune responses driven by pro-inflammatory cytokines and the events associated with tissue damage and repair, driven by caspases and angiogenin.
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Affiliation(s)
- Elżbieta Król
- School of Biological Sciences, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Patricia Noguera
- Fish Health and Welfare, Marine Scotland Science, Aberdeen, United Kingdom
| | - Sophie Shaw
- Centre for Genome-Enabled Biology and Medicine, University of Aberdeen, Aberdeen, United Kingdom
| | - Eoin Costelloe
- School of Biological Sciences, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | | | | | | | - Alex Douglas
- School of Biological Sciences, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Samuel A. M. Martin
- School of Biological Sciences, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom
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22
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Xin L, Huang B, Zhang H, Li C, Bai C, Wang C. OsHV-1 infection leads to mollusc tissue lesion and iron redistribution, revealing a strategy of iron limitation against pathogen. Metallomics 2020; 11:822-832. [PMID: 30843573 DOI: 10.1039/c9mt00018f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The mass mortality of molluscs caused by OsHV-1 infection has frequently occurred worldwide in recent years. Meanwhile the interaction between OsHV-1 and its host is largely unknown. Innate immunity mainly makes up the mollusc defense system, due to the lack of adaptive immunity in invertebrates. The iron limitation strategy is an indispensable facet of innate immunity across vertebrate and invertebrate species. In this study, an iron limitation strategy was interestingly found to contribute to mollusc innate immune responses against OsHV-1 infection. Firstly, ark clams, Scapharca broughtonii, were experimentally infected with OsHV-1, and serious hyperaemia in hepatopancreases and the erosion of gills were observed post OsHV-1 infection according to a histology assay. Meanwhile, based on quantification and Prussian blue staining, the process of iron efflux from ark clams was described post OsHV-1 infection. Secondly, ferritin, as an important iron storage protein, was characterized in ark clams and showed significant iron binding activity. According to the results of an immunohistochemistry assay, ferritin was supposed to be responsible for the iron translocation in ark clams post OsHV-1 infection. Its expression level was significantly fluctuant in response to OsHV-1 infection. Finally, oxidative stress was assessed by the analyses of H2O2 content, total antioxidant capacity and MDA level post OsHV-1 infection. Supplementary iron was found to promote ROS generation and death of hemocytes in vivo. These results highlighted that microenvironment changes in the essential nutrient iron should be an important aspect of the pathogenesis of OsHV-1 disease.
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Affiliation(s)
- Lusheng Xin
- Qingdao Key Laboratory of Mariculture Epidemiology and Biosecurity, Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, P. R. China.
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23
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Genome-wide association mapping and accuracy of predictions for amoebic gill disease in Atlantic salmon (Salmo salar). Sci Rep 2020; 10:6435. [PMID: 32296114 PMCID: PMC7160127 DOI: 10.1038/s41598-020-63423-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 03/30/2020] [Indexed: 11/09/2022] Open
Abstract
Amoebic gill disease (AGD) is a parasitic disease caused by the amoeba Paramoeba perurans, which colonizes the gill tissues and causes distress for the host. AGD can cause high morbidity and mortalities in salmonid and non-salmonid fish species. To understand the genetic basis of AGD and improve health status of farmed A. salmon, a population of ~ 6,100 individuals belonging to 150 full-sib families was monitored for development of AGD in the sea of Ireland. The population was followed for two rounds of AGD infections, and fish were gill scored to identify severity of disease in first (N = 3,663) and the second (N = 3,511) infection with freshwater treatment after the first gill-scoring. A subset of this gill-scored population (N = 1,141) from 119 full-sib families were genotyped with 57,184 SNPs using custom-made Affymetrix SNP-chip. GWAS analyses were performed which resulted in five significantly associated SNP variants distributed over chromosome 1, 2 and 5. Three candidate genes; c4, tnxb and slc44a4 were found within QTL region of chromosome 2. The tnxb and c4 genes are known to be a part of innate immune system, and may play a role in resistance to AGD. The gain in prediction accuracy obtained by involving genomic information was 9–17% higher than using traditional pedigree information.
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24
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Robledo D, Hamilton A, Gutiérrez AP, Bron JE, Houston RD. Characterising the mechanisms underlying genetic resistance to amoebic gill disease in Atlantic salmon using RNA sequencing. BMC Genomics 2020; 21:271. [PMID: 32228433 PMCID: PMC7106639 DOI: 10.1186/s12864-020-6694-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 03/24/2020] [Indexed: 12/16/2022] Open
Abstract
Background Gill health is one of the main concerns for Atlantic salmon aquaculture, and Amoebic Gill Disease (AGD), attributable to infection by the amoeba Neoparamoeba perurans, is a frequent cause of morbidity. In the absence of preventive measures, increasing genetic resistance of salmon to AGD via selective breeding can reduce the incidence of the disease and mitigate gill damage. Understanding the mechanisms leading to AGD resistance and the underlying causative genomic features can aid in this effort, while also providing critical information for the development of other control strategies. AGD resistance is considered to be moderately heritable, and several putative QTL have been identified. The aim of the current study was to improve understanding of the mechanisms underlying AGD resistance, and to identify putative causative genomic factors underlying the QTL. To achieve this, RNA was extracted from the gill and head kidney of AGD resistant and susceptible animals following a challenge with N. perurans, and sequenced. Results Comparison between resistant and susceptible animals primarily highlighted differences mainly in the local immune response in the gill, involving red blood cell genes and genes related to immune function and cell adhesion. Differentially expressed immune genes pointed to a contrast in Th2 and Th17 responses, which is consistent with the increased heritability observed after successive challenges with the amoeba. Five QTL-region candidate genes showed differential expression, including a gene connected to interferon responses (GVINP1), a gene involved in systemic inflammation (MAP4K4), and a positive regulator of apoptosis (TRIM39). Analyses of allele-specific expression highlighted a gene in the QTL region on chromosome 17, cellular repressor of E1A-stimulated genes 1 (CREG1), showing allelic differential expression suggestive of a cis-acting regulatory variant. Conclusions In summary, this study provides new insights into the mechanisms of resistance to AGD in Atlantic salmon, and highlights candidate genes for further functional studies that can further elucidate the genomic mechanisms leading to resistance and contribute to enhancing salmon health via improved genomic selection.
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Affiliation(s)
- Diego Robledo
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK.
| | - Alastair Hamilton
- Landcatch Natural Selection Ltd., Roslin Innovation Centre, University of Edinburgh, Midlothian, EH25 9RG, UK.,Hendrix Genetics Aquaculture BV/ Netherlands, Villa 'de Körver', Spoorstraat 69, 5831 CK, Boxmeer, Netherlands
| | - Alejandro P Gutiérrez
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK
| | - James E Bron
- Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Ross D Houston
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK.
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25
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Jia B, Delphino MKVC, Awosile B, Hewison T, Whittaker P, Morrison D, Kamaitis M, Siah A, Milligan B, Johnson SC, Gardner IA. Review of infectious agent occurrence in wild salmonids in British Columbia, Canada. JOURNAL OF FISH DISEASES 2020; 43:153-175. [PMID: 31742733 DOI: 10.1111/jfd.13084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/22/2019] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
Wild Pacific salmonids (WPS) are economically and culturally important to the Pacific North region. Most recently, some populations of WPS have been in decline. Of hypothesized factors contributing to the decline, infectious agents have been postulated to increase the risk of mortality in Pacific salmon. We present a literature review of both published journal and unpublished data to describe the distribution of infectious agents reported in wild Pacific salmonid populations in British Columbia (BC), Canada. We targeted 10 infectious agents, considered to potentially cause severe economic losses in Atlantic salmon or be of conservation concern for wild salmon in BC. The findings indicated a low frequency of infectious hematopoietic necrosis virus, piscine orthoreovirus, viral haemorrhagic septicaemia virus, Aeromonas salmonicida, Renibacterium salmoninarum, Piscirickettsia salmonis and other Rickettsia-like organisms, Yersinia ruckeri, Tenacibaculum maritimum and Moritella viscosa. No positive results were reported for infestations with Paramoeba perurans in peer-reviewed papers and the DFO Fish Pathology Program database. This review synthesizes existing information, as well as gaps therein, that can support the design and implementation of a long-term surveillance programme of infectious agents in wild salmonids in BC.
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Affiliation(s)
- Beibei Jia
- Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Marina K V C Delphino
- Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Babafela Awosile
- Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Tim Hewison
- Grieg Seafood BC Ltd., Campbell River, BC, Canada
| | | | | | | | - Ahmed Siah
- British Columbia Centre for Aquatic Health Sciences, Campbell River, BC, Canada
| | | | - Stewart C Johnson
- Pacific Biological Station, Fisheries and Oceans Canada (DFO), Nanaimo, BC, Canada
| | - Ian A Gardner
- Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
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26
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Teffer AK, Carr J, Tabata A, Schulze A, Bradbury I, Deschamps D, Gillis CA, Brunsdon EB, Mordecai G, Miller KM. A molecular assessment of infectious agents carried by Atlantic salmon at sea and in three eastern Canadian rivers, including aquaculture escapees and North American and European origin wild stocks. Facets (Ott) 2020. [DOI: 10.1139/facets-2019-0048] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Infectious agents are key components of animal ecology and drivers of host population dynamics. Knowledge of their diversity and transmission in the wild is necessary for the management and conservation of host species like Atlantic salmon ( Salmo salar). Although pathogen exchange can occur throughout the salmon life cycle, evidence is lacking to support transmission during population mixing at sea or between farmed and wild salmon due to aquaculture exposure. We tested these hypotheses using a molecular approach that identified infectious agents and transmission potential among sub-adult Atlantic salmon at marine feeding areas and adults in three eastern Canadian rivers with varying aquaculture influence. We used high-throughput qPCR to quantify infection profiles and next generation sequencing to measure genomic variation among viral isolates. We identified 14 agents, including five not yet described as occurring in Eastern Canada. Phylogenetic analysis of piscine orthoreovirus showed homology between isolates from European and North American origin fish at sea, supporting the hypothesis of intercontinental transmission. We found no evidence to support aquaculture influence on wild adult infections, which varied relative to environmental conditions, life stage, and host origin. Our findings identify research opportunities regarding pathogen transmission and biological significance for wild Atlantic salmon populations.
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Affiliation(s)
- Amy K. Teffer
- Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Jonathan Carr
- Atlantic Salmon Federation, Chamcook, NB E5B 3A9, Canada
| | - Amy Tabata
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, Canada
| | - Angela Schulze
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, Canada
| | - Ian Bradbury
- Salmonids Section, Fisheries and Oceans Canada, St. John’s, NF A1C 5X1, Canada
| | - Denise Deschamps
- Ministère des Forêts, de la Faune et des Parcs du Québec, Direction de l’expertise sur la faune aquatique, Quebec, QC G1S 4X4, Canada
| | | | | | - Gideon Mordecai
- Department of Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
| | - Kristina M. Miller
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, Canada
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Gjessing MC, Steinum T, Olsen AB, Lie KI, Tavornpanich S, Colquhoun DJ, Gjevre AG. Histopathological investigation of complex gill disease in sea farmed Atlantic salmon. PLoS One 2019; 14:e0222926. [PMID: 31581255 PMCID: PMC6776330 DOI: 10.1371/journal.pone.0222926] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/10/2019] [Indexed: 12/24/2022] Open
Abstract
Various agents including Ca. Piscichlamydia salmonis, Ca. Branchiomonas cysticola, Desmozoon lepeophtherii, Paramoeba perurans and salmon gill poxvirus may be associated with complex gill disease in Atlantic salmon. Co-infections involving two or more of these agents are common and histopathological interpretation of lesions is therefore challenging. In this study, we developed a semi-quantitative scoring system for examination of histopathological gill lesions in sea-farmed Atlantic salmon suffering from gill disease. Following qPCR analysis of gills sampled for Ca. P. salmonis, Ca. B. cysticola, D. lepeophtherii and P. perurans from 22 geographically spread outbreaks, five cases representing different infectious loads and combinations of agents were chosen for histopathological scoring. Twenty-eight histological features were evaluated and potential associations between individual pathological changes and the occurrence of individual agents studied. The inter-observer agreement in interpretation of histological parameters between the three pathologists involved, was calculated to validate robustness of the scoring scheme. Seventeen histological parameters met the criteria for inter-observer agreement analysis and were included in the calculation. The three most frequent findings were identification of subepithelial leukocytes, epithelial cell hyperplasia and mucus cell hyperplasia. While few findings could be specifically related to particular agents, necrosis in hyperplastic lesions, pustules and necrosis of subepithelial cells appeared to be associated with the presence of Ca. B. cysticola. Further, lesion profiles clearly support the previously identified association between P. perurans and pathological changes associated with AGD. Very few pathological changes were observed in the single case in which Ca. P. salmonis was the dominating agent. Some lesions were only very rarely observed e.g. chloride cell necrosis, epithelial cell apoptosis, lamellar deposition of melanin and haemophagocytosis. The scoring scheme developed and applied was robust and sensitive. A less extensive scheme for routine diagnostic use is proposed.
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Harmful Fouling Communities on Fish Farms in the SW Mediterranean Sea: Composition, Growth and Reproductive Periods. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2019. [DOI: 10.3390/jmse7090288] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Biological fouling organisms on fish cages represent a major issue and costly factor in marine finfish aquaculture. Cnidarians have been identified as one of the most problematical groups, contributing significantly to the occlusion and structural stress of the cage nets, but also dramatically affecting farmed species health in aquaculture facilities worldwide. Recently, significant relationships were established in different Spanish aquaculture facilities between hydrozoans and juvenile fish affected by gill injuries and mortality episodes. Community composition, growth rate and reproductive potential of biofouling were monitored on fish cages over two seasonal periods of fry cages farming, located in southern Spain (SW Alboran Sea), with a special focus on cnidarians. Biomass and community composition of biofouling changed with time and between studied periods, with a marked seasonality in colonization periods and taxonomic composition, particularly for the colonial hydrozoans. The hydroids Ectopleura larynx and Pennaria disticha were found at the highest densities. P. disticha was responsible for major biomass contribution to total hydroid biomass with the fastest growth rates. In addition, actinulae larvae of E. larynx were identified in zooplankton samples at high densities especially during periods of fry introduction in sea cages (when fish are highly vulnerable). These results corroborate evidence of the detrimental influence of fouling cnidarians in Mediterranean finfish aquaculture due to a direct harmful impact on fish health. Investigations on population dynamics, reproductive biology and envenomation potential of fouling hydrozoans should be regarded as key component of best monitoring practices to ensure good farmed fish welfare, maximization of aquaculture production and overall marine spatial planning.
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Tinta T, Kogovšek T, Klun K, Malej A, Herndl GJ, Turk V. Jellyfish-Associated Microbiome in the Marine Environment: Exploring Its Biotechnological Potential. Mar Drugs 2019; 17:E94. [PMID: 30717239 PMCID: PMC6410321 DOI: 10.3390/md17020094] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 01/25/2019] [Accepted: 01/29/2019] [Indexed: 12/25/2022] Open
Abstract
Despite accumulating evidence of the importance of the jellyfish-associated microbiome to jellyfish, its potential relevance to blue biotechnology has only recently been recognized. In this review, we emphasize the biotechnological potential of host⁻microorganism systems and focus on gelatinous zooplankton as a host for the microbiome with biotechnological potential. The basic characteristics of jellyfish-associated microbial communities, the mechanisms underlying the jellyfish-microbe relationship, and the role/function of the jellyfish-associated microbiome and its biotechnological potential are reviewed. It appears that the jellyfish-associated microbiome is discrete from the microbial community in the ambient seawater, exhibiting a certain degree of specialization with some preferences for specific jellyfish taxa and for specific jellyfish populations, life stages, and body parts. In addition, different sampling approaches and methodologies to study the phylogenetic diversity of the jellyfish-associated microbiome are described and discussed. Finally, some general conclusions are drawn from the existing literature and future research directions are highlighted on the jellyfish-associated microbiome.
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Affiliation(s)
- Tinkara Tinta
- Department of Limnology and Bio-Oceanography, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
- Marine Biology Station Piran, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia.
| | - Tjaša Kogovšek
- Marine Biology Station Piran, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia.
| | - Katja Klun
- Marine Biology Station Piran, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia.
| | - Alenka Malej
- Marine Biology Station Piran, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia.
| | - Gerhard J Herndl
- Department of Limnology and Bio-Oceanography, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
- NIOZ, Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research, Utrecht University, 1790 AB Den Burg, The Netherlands.
| | - Valentina Turk
- Marine Biology Station Piran, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia.
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30
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LeBlanc F, Ditlecadet D, Arseneau JR, Steeves R, Boston L, Boudreau P, Gagné N. Isolation and identification of a novel salmon gill poxvirus variant from Atlantic salmon in Eastern Canada. JOURNAL OF FISH DISEASES 2019; 42:315-318. [PMID: 30511390 DOI: 10.1111/jfd.12922] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 10/12/2018] [Accepted: 10/12/2018] [Indexed: 06/09/2023]
Affiliation(s)
- Francis LeBlanc
- Gulf Fisheries Centre, Fisheries& Oceans Canada, Moncton, New Brunswick, Canada
| | - Delphine Ditlecadet
- Gulf Fisheries Centre, Fisheries& Oceans Canada, Moncton, New Brunswick, Canada
| | - Jean-René Arseneau
- Gulf Fisheries Centre, Fisheries& Oceans Canada, Moncton, New Brunswick, Canada
| | - Royce Steeves
- Gulf Fisheries Centre, Fisheries& Oceans Canada, Moncton, New Brunswick, Canada
| | - Linda Boston
- Gulf Fisheries Centre, Fisheries& Oceans Canada, Moncton, New Brunswick, Canada
| | - Pascal Boudreau
- Gulf Fisheries Centre, Fisheries& Oceans Canada, Moncton, New Brunswick, Canada
| | - Nellie Gagné
- Gulf Fisheries Centre, Fisheries& Oceans Canada, Moncton, New Brunswick, Canada
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31
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Neave MJ, Apprill A, Aeby G, Miyake S, Voolstra CR. Microbial Communities of Red Sea Coral Reefs. CORAL REEFS OF THE RED SEA 2019. [DOI: 10.1007/978-3-030-05802-9_4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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32
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Marcos-López M, Calduch-Giner JA, Mirimin L, MacCarthy E, Rodger HD, O'Connor I, Sitjà-Bobadilla A, Pérez-Sánchez J, Piazzon MC. Gene expression analysis of Atlantic salmon gills reveals mucin 5 and interleukin 4/13 as key molecules during amoebic gill disease. Sci Rep 2018; 8:13689. [PMID: 30209326 PMCID: PMC6135806 DOI: 10.1038/s41598-018-32019-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 08/20/2018] [Indexed: 12/19/2022] Open
Abstract
Amoebic gill disease (AGD) is one of the main diseases affecting Atlantic salmon (Salmo salar L.) mariculture. Hallmarks of AGD are hyperplasia of the lamellar epithelium and increased production of gill mucus. This study investigated the expression of genes involved in mucus secretion, cell cycle regulation, immunity and oxidative stress in gills using a targeted 21-gene PCR array. Gill samples were obtained from experimental and natural Neoparamoeba perurans infections, and sampling points included progressive infection stages and post-freshwater treatment. Up-regulation of genes related to mucin secretion and cell proliferation, and down-regulation of pro-inflammatory and pro-apoptotic genes were associated with AGD severity, while partial restoration of the gill homeostasis was detected post-treatment. Mucins and Th2 cytokines accoun ted for most of the variability observed between groups highlighting their key role in AGD. Two mucins (muc5, muc18) showed differential regulation upon disease. Substantial up-regulation of the secreted muc5 was detected in clinical AGD, and the membrane bound muc18 showed an opposite pattern. Th2 cytokines, il4/13a and il4/13b2, were significantly up-regulated from 2 days post-infection onwards, and changes were lesion-specific. Despite the differences between experimental and natural infections, both yielded comparable results that underline the importance of the studied genes in the respiratory organs of fish, and during AGD progression.
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Affiliation(s)
- Mar Marcos-López
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Co., Galway, H91 T8NW, Ireland. .,FishVet Group Ireland, Unit 7b Oranmore Business Park, Oranmore, Co, Galway, H91 XP3F, Ireland.
| | - Josep A Calduch-Giner
- Nutrigenomics and Fish Growth Endocrinology Group, Instituto de Acuicultura Torre de la Sal (IATS-CSIC), Castellón, 12595, Spain
| | - Luca Mirimin
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Co., Galway, H91 T8NW, Ireland
| | - Eugene MacCarthy
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Co., Galway, H91 T8NW, Ireland
| | - Hamish D Rodger
- FishVet Group Ireland, Unit 7b Oranmore Business Park, Oranmore, Co, Galway, H91 XP3F, Ireland
| | - Ian O'Connor
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Co., Galway, H91 T8NW, Ireland
| | - Ariadna Sitjà-Bobadilla
- Fish Pathology Group, Instituto de Acuicultura Torre de la Sal (IATS-CSIC), Castellón, 12595, Spain
| | - Jaume Pérez-Sánchez
- Nutrigenomics and Fish Growth Endocrinology Group, Instituto de Acuicultura Torre de la Sal (IATS-CSIC), Castellón, 12595, Spain
| | - M Carla Piazzon
- Fish Pathology Group, Instituto de Acuicultura Torre de la Sal (IATS-CSIC), Castellón, 12595, Spain.
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33
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Herrero A, Thompson KD, Ashby A, Rodger HD, Dagleish MP. Complex Gill Disease: an Emerging Syndrome in Farmed Atlantic Salmon (Salmo salar L.). J Comp Pathol 2018; 163:23-28. [PMID: 30213370 DOI: 10.1016/j.jcpa.2018.07.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 07/05/2018] [Accepted: 07/18/2018] [Indexed: 11/19/2022]
Abstract
Gill disorders have become a significant problem during the marine phase of farming Atlantic salmon (Salmo salar L.). The term complex gill disease (CGD) includes a wide range of clinical gill disease presentations generally occurring from the end of summer to early winter on marine Atlantic salmon farms. The gross and histological lesions observed are the resultant culmination of exposure to a mixture of environmental insults, pathogenic organisms and farm management practices. None of the three principal agents purportedly associated with CGD (Desmozoon lepeophtherii, salmon gill poxvirus or Candidatus Branchiomonas cysticola) have been cultured successfully in-vitro, so individual in-vivo challenge studies to identify their pathogenesis have not been possible. Studies of cohabitation of single pathogen-infected fish with naïve fish, and epidemiological investigations are required urgently to elucidate the roles of these pathogens and other factors in CGD.
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Affiliation(s)
- A Herrero
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland, United Kingdom
| | - K D Thompson
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland, United Kingdom
| | - A Ashby
- Fish Vet Group Ltd., 22 Carsegate Road, Inverness, Scotland, UK
| | - H D Rodger
- Fish Vet Group Ireland, Unit 7b Oranmore Business Park, Oranmore, Co. Galway, Ireland
| | - M P Dagleish
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland, United Kingdom.
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34
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Bloecher N, Powell M, Hytterød S, Gjessing M, Wiik-Nielsen J, Mohammad SN, Johansen J, Hansen H, Floerl O, Gjevre AG. Effects of cnidarian biofouling on salmon gill health and development of amoebic gill disease. PLoS One 2018; 13:e0199842. [PMID: 29979703 PMCID: PMC6034824 DOI: 10.1371/journal.pone.0199842] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 06/14/2018] [Indexed: 01/22/2023] Open
Abstract
This study examines the potential implications of biofouling management on the development of an infectious disease in Norwegian farmed salmon. The hydroid Ectopleura larynx frequently colonises cage nets at high densities (thousands of colonies per m2) and is released into the water during regular in-situ net cleaning. Contact with the hydroids’ nematocysts has the potential to cause irritation and pathological damage to salmon gills. Amoebic gill disease (AGD), caused by the amoeba Paramoeba perurans, is an increasingly international health challenge in Atlantic salmon farming. AGD often occurs concomitantly with other agents of gill disease. This study used laboratory challenge trials to: (1) characterise the gill pathology resulting from the exposure of salmon to hydroids, and (2) investigate if such exposure can predispose the fish to secondary infections–using P. perurans as an example. Salmon in tanks were exposed either to freshly ‘shredded’ hydroids resembling waste material from net cleaning, or to authentic concentrations of free-living P. perurans, or first to ‘shredded’ hydroids and then to P. perurans. Gill health (AGD gill scores, non-specific gill scores, lamellar thrombi, epithelial hyperplasia) was monitored over 5 weeks and compared to an untreated control group. Nematocysts of E. larynx contained in cleaning waste remained active following high-pressure cleaning, resulting in higher non-specific gill scores in salmon up to 1 day after exposure to hydroids. Higher average numbers of gill lamellar thrombi occurred in fish up to 7 days after exposure to hydroids. However, gill lesions caused by hydroids did not affect the infection rates of P. perurans or the disease progression of AGD. This study discusses the negative impacts hydroids and current net cleaning practices can have on gill health and welfare of farmed salmon, highlights existing knowledge gaps and reiterates the need for alternative approaches to net cleaning.
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Affiliation(s)
| | - Mark Powell
- Norwegian Institute for Water Research, Bergen, Norway
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35
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Downes JK, Yatabe T, Marcos-Lopez M, Rodger HD, MacCarthy E, O'Connor I, Collins E, Ruane NM. Investigation of co-infections with pathogens associated with gill disease in Atlantic salmon during an amoebic gill disease outbreak. JOURNAL OF FISH DISEASES 2018; 41:1217-1227. [PMID: 29806080 DOI: 10.1111/jfd.12814] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/13/2018] [Accepted: 03/14/2018] [Indexed: 06/08/2023]
Abstract
Gill diseases are a complex and multifactorial challenge for marine farmed Atlantic salmon. Co-infections with putative pathogens are common on farms; however, there is a lack of knowledge in relation to the potential effect co-infections may have on pathology. The objective of this study was to determine the prevalence and potential effects of Neoparamoeba perurans, Desmozoon lepeophtherii, Candidatus Branchiomonas cysticola, Tenacibaculum maritimum and salmon gill poxvirus (SGPV) during a longitudinal study on a marine Atlantic salmon farm. Real-time PCR was used to determine the presence and sequential infection patterns of these pathogens on gill samples collected from stocking until harvest. A number of multilevel models were used to determine the effect of these putative pathogens on gill health (measured as gill histopathology score), while adjusting for the effect of water temperature and time since the last freshwater treatment. Results indicate that between 12 and 16 weeks post-seawater transfer (wpst), colonization of the gills by all pathogens had commenced and by week 16 of marine production each of the pathogens had been detected. D. lepeophtherii and Candidatus B. cysticola were by far the most prevalent of the potential pathogens detected during this study. Detections of T. maritimum were found to be significantly correlated with temperature showing distinct seasonality. Salmon gill poxvirus was found to be highly sporadic and detected in the first sampling point, suggesting a carryover from the freshwater stage of production. Finally, the model results indicated no clear effect between any of the pathogens. Additionally, the models showed that the only variable which had a consistent effect on the histology score was N. perurans.
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Affiliation(s)
- J K Downes
- Fish Health Unit, Marine Institute, Oranmore, Galway, Ireland
- Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Galway, Ireland
| | - T Yatabe
- Department Medicine & Epidemiology, School Veterinary Medicine, Center for Animal Disease Modeling and Surveillance (CADMS), University of California, Davis, Davis, CA, USA
| | - M Marcos-Lopez
- Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Galway, Ireland
- Fish Vet Group, Unit 7b, Oranmore, Galway, Ireland
| | - H D Rodger
- Fish Vet Group, Unit 7b, Oranmore, Galway, Ireland
| | - E MacCarthy
- Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Galway, Ireland
| | - I O'Connor
- Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Galway, Ireland
| | - E Collins
- Fish Health Unit, Marine Institute, Oranmore, Galway, Ireland
| | - N M Ruane
- Fish Health Unit, Marine Institute, Oranmore, Galway, Ireland
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Sood N, Pradhan PK, Verma DK, Yadav MK, Dev AK, Swaminathan TR, Sood NK. Candidatus Actinochlamydia pangasiae sp. nov. (Chlamydiales, Actinochlamydiaceae), a bacterium associated with epitheliocystis in Pangasianodon hypophthalmus. JOURNAL OF FISH DISEASES 2018; 41:281-290. [PMID: 28940578 DOI: 10.1111/jfd.12711] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 06/07/2023]
Abstract
Chlamydial infections are recognised as causative agent of epitheliocystis, reported from over 90 fish species. In the present study, the farmed striped catfish Pangasianodon hypophthalmus (14-15 cm, 70-90 g) with a history of cumulative mortality of about 23% during June and July 2015, were brought to the laboratory. The histopathological examination of gills from the affected fish revealed presence of granular basophilic intracellular inclusions, mostly at the base of the interlamellar region and in gill filaments. A concurrent infection with Trichodina spp., Ichthyobodo spp. and Dactylogyrus spp. was observed in the gills. The presence of chlamydial DNA in the gills of affected fish was confirmed by amplification and sequencing of 16S rRNA gene. BLAST-n analysis of these amplicons revealed maximum similarity (96%) with Candidatus Actinochlamydia clariae. On the basis of phylogenetic analysis, it was inferred that the epitheliocystis agents from striped catfish were novel and belonged to the taxon Ca. Actinochlamydia. It is proposed that epitheliocystis agents from striped catfish will be named as Ca. Actinochlamydia pangasiae. The 16S rRNA gene amplicons from novel chlamydiae were labelled and linked to inclusions by in situ hybridisation. This is the first report of epitheliocystis from India in a new fish host P. hypophthalmus.
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Affiliation(s)
- N Sood
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - P K Pradhan
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - D K Verma
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - M K Yadav
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - A K Dev
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, India
| | - T R Swaminathan
- Peninsular and Marine Fish Genetic Resources Centre, ICAR-NBFGR, Kochi, Kerala
| | - N K Sood
- Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India
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Can biosecurity and local network properties predict pathogen species richness in the salmonid industry? PLoS One 2018; 13:e0191680. [PMID: 29381760 PMCID: PMC5790274 DOI: 10.1371/journal.pone.0191680] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 01/09/2018] [Indexed: 01/08/2023] Open
Abstract
Salmonid farming in Ireland is mostly organic, which implies limited disease treatment options. This highlights the importance of biosecurity for preventing the introduction and spread of infectious agents. Similarly, the effect of local network properties on infection spread processes has rarely been evaluated. In this paper, we characterized the biosecurity of salmonid farms in Ireland using a survey, and then developed a score for benchmarking the disease risk of salmonid farms. The usefulness and validity of this score, together with farm indegree (dichotomized as ≤ 1 or > 1), were assessed through generalized Poisson regression models, in which the modeled outcome was pathogen richness, defined here as the number of different diseases affecting a farm during a year. Seawater salmon (SW salmon) farms had the highest biosecurity scores with a median (interquartile range) of 82.3 (5.4), followed by freshwater salmon (FW salmon) with 75.2 (8.2), and freshwater trout (FW trout) farms with 74.8 (4.5). For FW salmon and trout farms, the top ranked model (in terms of leave-one-out information criteria, looic) was the null model (looic = 46.1). For SW salmon farms, the best ranking model was the full model with both predictors and their interaction (looic = 33.3). Farms with a higher biosecurity score were associated with lower pathogen richness, and farms with indegree > 1 (i.e. more than one fish supplier) were associated with increased pathogen richness. The effect of the interaction between these variables was also important, showing an antagonistic effect. This would indicate that biosecurity effectiveness is achieved through a broader perspective on the subject, which includes a minimization in the number of suppliers and hence in the possibilities for infection to enter a farm. The work presented here could be used to elaborate indicators of a farm’s disease risk based on its biosecurity score and indegree, to inform risk-based disease surveillance and control strategies for private and public stakeholders.
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Zhou QJ, Chai FC, Chen J. First record of Glugea plecoglossi (Takahashi & Egusa, 1977), a microsporidian parasite of ayu (Plecoglossus altivelis altivelis Temminck & Schlegel, 1846) in Mainland China. JOURNAL OF FISH DISEASES 2018; 41:165-169. [PMID: 28707704 DOI: 10.1111/jfd.12674] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/27/2017] [Accepted: 05/29/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Q J Zhou
- Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo, China
| | - F C Chai
- Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo, China
| | - J Chen
- Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo, China
- Key Laboratory of Applied Marine Biotechnology of Ministry of Education, Ningbo University, Ningbo, China
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39
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Hvas M, Karlsbakk E, Mæhle S, Wright DW, Oppedal F. The gill parasite Paramoeba perurans compromises aerobic scope, swimming capacity and ion balance in Atlantic salmon. CONSERVATION PHYSIOLOGY 2017; 5:cox066. [PMID: 29218225 PMCID: PMC5710617 DOI: 10.1093/conphys/cox066] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/24/2017] [Accepted: 11/06/2017] [Indexed: 05/27/2023]
Abstract
The parasitic amoeba Paramoeba perurans is an aetiological agent of amoebic gill disease (AGD), a serious problem in seawater salmonid aquaculture globally. Other finfish species are also infected and infection events may be associated with periods of unusual high temperatures. Currently little is known about the impact of AGD on wild fish, but in a time with global warming and increasing aquaculture production this potential threat could be on the rise. A better understanding of the pathophysiology of infected fish is therefore warranted. In this study, groups of Atlantic salmon with and without AGD were tested in a large swim tunnel respirometer in seawater at 13°C to assess oxygen uptake, swimming capacity and blood parameters. Standard metabolic rates were similar between groups, but the maximum rate of oxygen uptake was drastically reduced in infected fish, which resulted in a smaller aerobic scope (AS) of 203 mg O2 kg-1 h-1 compared to 406 mg O2 kg-1 h-1 in healthy fish. The critical swimming speed was 2.5 body lengths s-1 in infected fish and 3.0 body lengths s-1 in healthy ones. Furthermore, AGD fish had lower haematocrit and [haemoglobin], but similar condition factor compared to healthy fish. Prior to swim trials infected fish had higher plasma osmolality, elevated plasma [Na+], [Cl-] and [cortisol], indicating reduced capacity to maintain ionic homoeostasis as well as chronic stress during routine conditions. These results demonstrate that AGD compromises gill function both in terms of gas exchange and ion regulation, and consequently the capacity for aerobic activity is reduced. Reduced AS due to the P. perurans infections is likely to interfere with appetite, growth and overall survival, even more so in the context of a warmer and more hypoxic future.
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Affiliation(s)
- Malthe Hvas
- Institute of Marine Research, 5984 Matredal, Norway
| | - Egil Karlsbakk
- Institute of Marine Research, 5984 Matredal, Norway
- Department of Biology, University of Bergen, 5020 Bergen, Norway
| | - Stig Mæhle
- Institute of Marine Research, 5984 Matredal, Norway
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40
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Småge SB, Brevik ØJ, Frisch K, Watanabe K, Duesund H, Nylund A. Concurrent jellyfish blooms and tenacibaculosis outbreaks in Northern Norwegian Atlantic salmon (Salmo salar) farms. PLoS One 2017; 12:e0187476. [PMID: 29095885 PMCID: PMC5667831 DOI: 10.1371/journal.pone.0187476] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/22/2017] [Indexed: 11/18/2022] Open
Abstract
Tenacibaculosis is an increasing problem in the Norwegian Atlantic salmon aquaculture industry causing significant economic losses. In September 2015, two separate outbreaks of suspected tenacibaculosis occurred at two Atlantic salmon farms in Finnmark County in Northern Norway. The events resulted in major losses of smolts newly transferred into seawater. Prior to, and during the outbreaks, large numbers of small jellyfish, identified as Dipleurosoma typicum (Boeck) were observed in the vicinity of the farms and inside the net-pens. This study investigates the possible link between the jellyfish, Tenacibaculum spp. and the tenacibaculosis outbreaks. Bacteriology, histology, scanning and transmission electron microscopy, and real-time RT-PCR screening were performed on both fish and jellyfish samples. Based on the findings, Tenacibaculum finnmarkense was found to be the dominant bacteria associated with the tenacibaculosis outbreaks at both sites and that D. typicum is unlikely to be a vector for this fish pathogenic bacterium. However, results do show that the jellyfish caused direct damage to the fish's skin and may have exacerbated the bacterial infection by allowing an entry point for bacteria.
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Affiliation(s)
- Sverre Bang Småge
- Cermaq Group AS, Dronning Eufemiasgate 16, Oslo, Norway
- Fish Disease Research Group, Department of Biology, University of Bergen, Thormøhlensgate 55, Bergen, Norway
- * E-mail:
| | - Øyvind Jakobsen Brevik
- Cermaq Group AS, Dronning Eufemiasgate 16, Oslo, Norway
- Fish Disease Research Group, Department of Biology, University of Bergen, Thormøhlensgate 55, Bergen, Norway
| | - Kathleen Frisch
- Cermaq Group AS, Dronning Eufemiasgate 16, Oslo, Norway
- Fish Disease Research Group, Department of Biology, University of Bergen, Thormøhlensgate 55, Bergen, Norway
| | - Kuninori Watanabe
- Fish Disease Research Group, Department of Biology, University of Bergen, Thormøhlensgate 55, Bergen, Norway
| | | | - Are Nylund
- Fish Disease Research Group, Department of Biology, University of Bergen, Thormøhlensgate 55, Bergen, Norway
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41
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Tengs T, Rimstad E. Emerging pathogens in the fish farming industry and sequencing-based pathogen discovery. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 75:109-119. [PMID: 28167074 DOI: 10.1016/j.dci.2017.01.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/27/2017] [Accepted: 01/31/2017] [Indexed: 06/06/2023]
Abstract
The use of large scale DNA/RNA sequencing has become an integral part of biomedical research. Reduced sequencing costs and the availability of efficient computational resources has led to a revolution in how problems concerning genomics and transcriptomics are addressed. Sequencing-based pathogen discovery represents one example of how genetic data can now be used in ways that were previously considered infeasible. Emerging pathogens affect both human and animal health due to a multitude of factors, including globalization, a shifting environment and an increasing human population. Fish farming represents a relevant, interesting and challenging system to study emerging pathogens. This review summarizes recent progress in pathogen discovery using sequence data, with particular emphasis on viruses in Atlantic salmon (Salmo salar).
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Affiliation(s)
- Torstein Tengs
- Department of Chemistry, Biotechnology and Food Sciences, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, 1430 Aas, Norway.
| | - Espen Rimstad
- Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, 0033 Oslo, Norway
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42
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Wiik-Nielsen J, Gjessing M, Solheim HT, Litlabø A, Gjevre AG, Kristoffersen AB, Powell MD, Colquhoun DJ. Ca. Branchiomonas cysticola, Ca. Piscichlamydia salmonis and Salmon Gill Pox Virus transmit horizontally in Atlantic salmon held in fresh water. JOURNAL OF FISH DISEASES 2017; 40:1387-1394. [PMID: 28261804 DOI: 10.1111/jfd.12613] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/27/2016] [Accepted: 12/28/2016] [Indexed: 05/27/2023]
Abstract
Elucidation of the role of infectious agents putatively involved in gill disease is commonly hampered by the lack of culture systems for these organisms. In this study, a farmed population of Atlantic salmon pre-smolts, displaying proliferative gill disease with associated Candidatus Branchiomonas cysticola, Ca. Piscichlamydia salmonis and Atlantic salmon gill pox virus (SGPV) infections, was identified. A subpopulation of the diseased fish was used as a source of waterborne infection towards a population of naïve Atlantic salmon pre-smolts. Ca. B. cysticola infection became established in exposed naïve fish at high prevalence within the first month of exposure and the bacterial load increased over the study period. Ca. P. salmonis and SGPV infections were identified only at low prevalence in exposed fish during the trial. Although clinically healthy, at termination of the trial the exposed, naïve fish displayed histologically visible pathological changes typified by epithelial hyperplasia and subepithelial inflammation with associated bacterial inclusions, confirmed by fluorescent in situ hybridization to contain Ca. B. cysticola. The results strongly suggest that Ca. B. cysticola infections transmit directly from fish to fish and that the bacterium is directly associated with the pathological changes observed in the exposed, previously naïve fish.
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Affiliation(s)
| | - M Gjessing
- Norwegian Veterinary Institute, Oslo, Norway
| | - H T Solheim
- Norwegian Institute of Public Health, Oslo, Norway
| | | | - A-G Gjevre
- Norwegian Veterinary Institute, Oslo, Norway
| | | | - M D Powell
- Norwegian Institute for Water Research, Bergen, Norway
- University of Bergen, Bergen, Norway
| | - D J Colquhoun
- Norwegian Veterinary Institute, Oslo, Norway
- University of Bergen, Bergen, Norway
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43
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Tanifuji G, Cenci U, Moog D, Dean S, Nakayama T, David V, Fiala I, Curtis BA, Sibbald SJ, Onodera NT, Colp M, Flegontov P, Johnson-MacKinnon J, McPhee M, Inagaki Y, Hashimoto T, Kelly S, Gull K, Lukeš J, Archibald JM. Genome sequencing reveals metabolic and cellular interdependence in an amoeba-kinetoplastid symbiosis. Sci Rep 2017; 7:11688. [PMID: 28916813 PMCID: PMC5601477 DOI: 10.1038/s41598-017-11866-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 08/31/2017] [Indexed: 01/12/2023] Open
Abstract
Endosymbiotic relationships between eukaryotic and prokaryotic cells are common in nature. Endosymbioses between two eukaryotes are also known; cyanobacterium-derived plastids have spread horizontally when one eukaryote assimilated another. A unique instance of a non-photosynthetic, eukaryotic endosymbiont involves members of the genus Paramoeba, amoebozoans that infect marine animals such as farmed fish and sea urchins. Paramoeba species harbor endosymbionts belonging to the Kinetoplastea, a diverse group of flagellate protists including some that cause devastating diseases. To elucidate the nature of this eukaryote-eukaryote association, we sequenced the genomes and transcriptomes of Paramoeba pemaquidensis and its endosymbiont Perkinsela sp. The endosymbiont nuclear genome is ~9.5 Mbp in size, the smallest of a kinetoplastid thus far discovered. Genomic analyses show that Perkinsela sp. has lost the ability to make a flagellum but retains hallmark features of kinetoplastid biology, including polycistronic transcription, trans-splicing, and a glycosome-like organelle. Mosaic biochemical pathways suggest extensive ‘cross-talk’ between the two organisms, and electron microscopy shows that the endosymbiont ingests amoeba cytoplasm, a novel form of endosymbiont-host communication. Our data reveal the cell biological and biochemical basis of the obligate relationship between Perkinsela sp. and its amoeba host, and provide a foundation for understanding pathogenicity determinants in economically important Paramoeba.
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Affiliation(s)
- Goro Tanifuji
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Zoology, National Museum of Nature and Science, Tsukuba, Japan
| | - Ugo Cenci
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Daniel Moog
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada.,Laboratory for Cell Biology, Philipps University, Marburg, Germany
| | - Samuel Dean
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Takuro Nakayama
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Japan.,Graduate School of Life Sciences, Tohoku University, Tohoku, Japan
| | - Vojtěch David
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada.,Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Ivan Fiala
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Bruce A Curtis
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Shannon J Sibbald
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Naoko T Onodera
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada.,National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Morgan Colp
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Pavel Flegontov
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.,Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Jessica Johnson-MacKinnon
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada.,Institute for Marine and Antarctic Sciences, University of Tasmania, Launceston, Australia
| | - Michael McPhee
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Yuji Inagaki
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tetsuo Hashimoto
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Steven Kelly
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.,Faculty of Sciences, University of South Bohemia, České Budějovice, Czech Republic.,Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Toronto, Canada
| | - John M Archibald
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada. .,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada. .,Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Toronto, Canada.
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44
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Apablaza P, Frisch K, Brevik ØJ, Småge SB, Vallestad C, Duesund H, Mendoza J, Nylund A. Primary Isolation and Characterization of Tenacibaculum maritimum from Chilean Atlantic Salmon Mortalities Associated with a Pseudochattonella spp. Algal Bloom. JOURNAL OF AQUATIC ANIMAL HEALTH 2017; 29:143-149. [PMID: 28613984 DOI: 10.1080/08997659.2017.1339643] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This study presents the first isolation of Tenacibaculum maritimum from farmed Atlantic Salmon Salmo salar in Chile. The isolate, designated T. maritimum Ch-2402, was isolated from gills of Atlantic Salmon at a farm located in region X, Los Lagos, Chile, during the harmful algal bloom caused by Pseudochattonella spp. in February 2016. The algal bloom is reported to have caused 40,000 metric tons of mortality in this salmon farming area. The bacterium T. maritimum, which causes tenacibaculosis, is recognized as an important pathogen of marine fish worldwide. Genetic, phylogenetic, and phenotypic characterizations were used to describe the T. maritimum Ch-2402 isolate. The isolate was similar to the type strain of T. maritimum but was genetically unique. Tenacibaculum dicentrarchi isolates were also recovered during sampling from the same farm. Based on the fact that T. maritimum has been shown to cause disease in Atlantic Salmon in other regions, the presence of this bacterium poses a potential risk of disease to fish in the Chilean aquaculture industry. Received November 6, 2016; accepted May 29, 2017.
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Affiliation(s)
- Patricia Apablaza
- a Fish Disease Research Group, Department of Biology , University of Bergen , Thormøhlensgate 55, Bergen N-5020 , Norway
- b Cermaq Group AS , Dronning Eufemias Gate 16, Post Office Box 144, Sentrum , Oslo N-0102 , Norway
| | - Kathleen Frisch
- a Fish Disease Research Group, Department of Biology , University of Bergen , Thormøhlensgate 55, Bergen N-5020 , Norway
- b Cermaq Group AS , Dronning Eufemias Gate 16, Post Office Box 144, Sentrum , Oslo N-0102 , Norway
| | - Øyvind Jakobsen Brevik
- b Cermaq Group AS , Dronning Eufemias Gate 16, Post Office Box 144, Sentrum , Oslo N-0102 , Norway
| | - Sverre Bang Småge
- a Fish Disease Research Group, Department of Biology , University of Bergen , Thormøhlensgate 55, Bergen N-5020 , Norway
- b Cermaq Group AS , Dronning Eufemias Gate 16, Post Office Box 144, Sentrum , Oslo N-0102 , Norway
| | - Camilla Vallestad
- a Fish Disease Research Group, Department of Biology , University of Bergen , Thormøhlensgate 55, Bergen N-5020 , Norway
| | - Henrik Duesund
- b Cermaq Group AS , Dronning Eufemias Gate 16, Post Office Box 144, Sentrum , Oslo N-0102 , Norway
| | - Julio Mendoza
- c Cermaq Chile , Diego Portales 2000, Piso 10, Puerto Montt , Chile
| | - Are Nylund
- a Fish Disease Research Group, Department of Biology , University of Bergen , Thormøhlensgate 55, Bergen N-5020 , Norway
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45
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Weli SC, Dale OB, Hansen H, Gjessing MC, Rønneberg LB, Falk K. A case study of Desmozoon lepeophtherii infection in farmed Atlantic salmon associated with gill disease, peritonitis, intestinal infection, stunted growth, and increased mortality. Parasit Vectors 2017; 10:370. [PMID: 28764744 PMCID: PMC5540559 DOI: 10.1186/s13071-017-2303-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 07/20/2017] [Indexed: 11/25/2022] Open
Abstract
Background In September 2008, a disease outbreak characterized by acute, severe gill pathology and peritonitis, involving the gastrointestinal tract, was observed in an Atlantic salmon (Salmo salar L.) farm in north-western Norway. During subsequent sampling in November 2008 and January 2009, chronic proliferative gill inflammation and peritonitis was observed. Cumulative mortalities of 5.6–12.8% and severe growth retardation were observed. Routine diagnostic analysis revealed no diseases known to salmon at the time, but microsporidian infection of tissues was observed. Methods To characterize the disease outbreak, a combination of histopathology, in situ hybridization (ISH), chitin, calcofluor-white (CFW) staining, and real-time PCR were used to describe the disease progression with visualization of the D. lepeophtherii stages in situ. Results The presence of the microsporidian Desmozoon lepeophtherii was confirmed with real-time PCR, DNA sequencing and ISH, and the parasite was detected in association with acute lesions in the gills and peritoneum. ISH using a probe specific to small subunit 16S rRNA gene provided an effective tool for demonstrating the distribution of D. lepeophtherii in the tissue. Infection in the peritoneum seemed localized in and around pre-existing vaccine granulomas, and in the gastrointestinal walls. In the heart, kidney and spleen, the infection was most often associated with mononuclear leucocytes and macrophages, including melanomacrophages. Desmozoon lepeophtherii exospores were found in the nuclei of the gastrointestinal epithelium for the first time, suggesting a role of the gastrointestinal tract in the spread of spores to the environment. Conclusions This study describes the progression of D. lepeophtherii disease outbreak in an Atlantic salmon farm without any other known diseases present. Using different methods to examine the disease outbreak, new insight into the pathology of D. lepeophtherii was obtained. The parasite was localized in situ in association with severe tissue damage and inflammation in the gills, peritoneal cavity and in the gastrointestinal (GI) tract that links the parasite directly to the observed pathology.
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Affiliation(s)
- Simon Chioma Weli
- Norwegian Veterinary Institute, P.O.Box 750 Dep., N-0106, Oslo, Norway
| | - Ole Bendik Dale
- Norwegian Veterinary Institute, P.O.Box 750 Dep., N-0106, Oslo, Norway.
| | - Haakon Hansen
- Norwegian Veterinary Institute, P.O.Box 750 Dep., N-0106, Oslo, Norway
| | | | - Liv Birte Rønneberg
- Present address: Fiske-liv AS, Marine Harvest Apotekergt. 9A, 6004, Ålesund, Norway
| | - Knut Falk
- Norwegian Veterinary Institute, P.O.Box 750 Dep., N-0106, Oslo, Norway
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46
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Lima PC, Taylor RS, Cook M. Pseudocyst formation in the marine parasitic amoeba Neoparamoeba perurans: a short-term survival strategy to abrupt salinity variation. JOURNAL OF FISH DISEASES 2017; 40:1109-1113. [PMID: 28000922 DOI: 10.1111/jfd.12588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 10/20/2016] [Accepted: 10/20/2016] [Indexed: 06/06/2023]
Affiliation(s)
- P C Lima
- Integrated Sustainable Aquaculture Production, CSIRO Agriculture and Food, Woorim, QLD, Australia
| | - R S Taylor
- Integrated Sustainable Aquaculture Production, CSIRO Agriculture and Food, Hobart, TAS, Australia
| | - M Cook
- Integrated Sustainable Aquaculture Production, CSIRO Agriculture and Food, St Lucia, QLD, Australia
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47
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Marcos-López M, Espinosa Ruiz C, Rodger HD, O'Connor I, MacCarthy E, Esteban MÁ. Local and systemic humoral immune response in farmed Atlantic salmon (Salmo salar L.) under a natural amoebic gill disease outbreak. FISH & SHELLFISH IMMUNOLOGY 2017; 66:207-216. [PMID: 28501445 DOI: 10.1016/j.fsi.2017.05.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 05/05/2017] [Accepted: 05/09/2017] [Indexed: 06/07/2023]
Abstract
Amoebic gill disease (AGD), caused by the protozoan parasite Neoparamoeba perurans, is one of the most significant infectious diseases for Atlantic salmon (Salmo salar L.) mariculture. The present study investigated the humoral immune response (both local in gill mucus and systemic in serum) of farmed Atlantic salmon naturally infected with N. perurans in commercial sea pens, at two different stages of the disease and after freshwater treatment. Parameters analysed included activity of immune related enzymes (i.e. lysozyme, peroxidase, protease, anti-protease, esterase, alkaline phosphatase), IgM levels, and the terminal carbohydrate profile in the gill mucus. Overall, greater variations between groups were noted in the immune parameters determined in gill mucus than the equivalent in the serum. In gill mucus, IgM levels and peroxidase, lysozyme, esterase and protease activities were decreased in fish showing longer exposure time to the infection and higher disease severity, then showed a sequential increase after treatment. Results obtained highlight the capacity of gills to elicit a local response to the infection, indicate an impaired immune response at the later stages of the disease, and show partial reestablishment of the host immune status after freshwater treatment. In addition to providing data on the humoral response to AGD, this study increases knowledge on gill mucosal humoral immunity, since some of the parameters were analysed for the first time in gill mucus.
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Affiliation(s)
- Mar Marcos-López
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Co. Galway, Ireland; FishVet Group Ireland, Unit 7b Oranmore Business Park, Oranmore, Co. Galway, Ireland.
| | - Cristóbal Espinosa Ruiz
- Department of Cell Biology and Histology, Faculty of Biology, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", University of Murcia, Murcia, Spain
| | - Hamish D Rodger
- FishVet Group Ireland, Unit 7b Oranmore Business Park, Oranmore, Co. Galway, Ireland
| | - Ian O'Connor
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Co. Galway, Ireland
| | - Eugene MacCarthy
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Co. Galway, Ireland
| | - M Ángeles Esteban
- Department of Cell Biology and Histology, Faculty of Biology, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", University of Murcia, Murcia, Spain
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48
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A comparison of disease susceptibility and innate immune response between diploid and triploid Atlantic salmon (Salmo salar) siblings following experimental infection with Neoparamoeba perurans, causative agent of amoebic gill disease. Parasitology 2017; 144:1229-1242. [PMID: 28492111 PMCID: PMC5647666 DOI: 10.1017/s0031182017000622] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Few studies have focussed on the health and immunity of triploid Atlantic salmon and therefore much is still unknown about their response to commercially significant pathogens. This is important if triploid stocks are to be considered for full-scale commercial production. This study aimed to investigate and compare the response of triploid and diploid Atlantic salmon to an experimental challenge with Neoparamoeba perurans, causative agent of amoebic gill disease (AGD). This disease is economically significant for the aquaculture industry. The results indicated that ploidy had no significant effect on gross gill score or gill filaments affected, while infection and time had significant effects. Ploidy, infection and time did not affect complement or anti-protease activities. Ploidy had a significant effect on lysozyme activity at 21 days post-infection (while infection and time did not), although activity was within the ranges previously recorded for salmonids. Stock did not significantly affect any of the parameters measured. Based on the study results, it can be suggested that ploidy does not affect the manifestation or severity of AGD pathology or the serum innate immune response. Additionally, the serum immune response of diploid and triploid Atlantic salmon may not be significantly affected by amoebic gill disease.
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49
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Kim WS, Kong KH, Kim JO, Jung SJ, Kim JH, Oh MJ. Amoebic gill disease outbreak in marine fish cultured in Korea. J Vet Diagn Invest 2017; 29:357-361. [DOI: 10.1177/1040638717690783] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In 2015, 6.7–60% mortality was observed in black seabream ( Acanthopagrus schlegelii), rock bream ( Oplegnathus fasciatus), and gray mullet ( Mugil cephalus) farmed in the southern coast of Korea. On examination, numerous amoebae were found on the gills of these 3 fish species with detection rate of 100%. Some rock bream and gray mullet were coinfected with bacteria ( Pseudomonas anguilliseptica, Vibrio tapetis, or Vibrio anguillarum). Histologic examination revealed extensive hyperplastic epithelium and lamellar fusion in the gills. Numerous amoebae were seen between gill filaments. The amoebae collected from the 3 fish species had specific 630 bp of a partial 18S rRNA gene fragment for Neoparamoeba perurans. Phylogenetic analysis based on partial 18S rRNA gene nucleotide sequences revealed that these Korean amoeba isolates belonged to the N. perurans group. Based on our results, black seabream, rock bream, and gray mullet were added as new hosts for N. perurans.
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Affiliation(s)
- Wi-Sik Kim
- Department of Aqualife Medicine, College of Fisheries and Ocean Science, Chonnam National University, Yeosu, Korea (W-S Kim, Kong, J-O Kim, Jung)
- Faculty of Marine Bioscience and Technology, Gangneung-Wonju National University, Gangneung, Korea (J-H Kim)
| | - Kyoung-Hui Kong
- Department of Aqualife Medicine, College of Fisheries and Ocean Science, Chonnam National University, Yeosu, Korea (W-S Kim, Kong, J-O Kim, Jung)
- Faculty of Marine Bioscience and Technology, Gangneung-Wonju National University, Gangneung, Korea (J-H Kim)
| | - Jong-Oh Kim
- Department of Aqualife Medicine, College of Fisheries and Ocean Science, Chonnam National University, Yeosu, Korea (W-S Kim, Kong, J-O Kim, Jung)
- Faculty of Marine Bioscience and Technology, Gangneung-Wonju National University, Gangneung, Korea (J-H Kim)
| | - Sung-Ju Jung
- Department of Aqualife Medicine, College of Fisheries and Ocean Science, Chonnam National University, Yeosu, Korea (W-S Kim, Kong, J-O Kim, Jung)
- Faculty of Marine Bioscience and Technology, Gangneung-Wonju National University, Gangneung, Korea (J-H Kim)
| | - Jeong-Ho Kim
- Department of Aqualife Medicine, College of Fisheries and Ocean Science, Chonnam National University, Yeosu, Korea (W-S Kim, Kong, J-O Kim, Jung)
- Faculty of Marine Bioscience and Technology, Gangneung-Wonju National University, Gangneung, Korea (J-H Kim)
| | - Myung-Joo Oh
- Department of Aqualife Medicine, College of Fisheries and Ocean Science, Chonnam National University, Yeosu, Korea (W-S Kim, Kong, J-O Kim, Jung)
- Faculty of Marine Bioscience and Technology, Gangneung-Wonju National University, Gangneung, Korea (J-H Kim)
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Wiik-Nielsen J, Mo TA, Kolstad H, Mohammad SN, Hytterød S, Powell MD. Morphological diversity of Paramoeba perurans trophozoites and their interaction with Atlantic salmon, Salmo salar L., gills. JOURNAL OF FISH DISEASES 2016; 39:1113-1123. [PMID: 26775899 DOI: 10.1111/jfd.12444] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 11/04/2015] [Accepted: 11/04/2015] [Indexed: 06/05/2023]
Abstract
Amoebic gill disease (AGD) caused by the ectoparasite Paramoeba perurans affects several cultured marine fish species worldwide. In this study, the morphology and ultrastructure of P. perurans in vitro and in vivo was investigated using scanning and transmission electron microscopy (SEM and TEM, respectively). Amoebae cultures contained several different morphologies ranging from a distinct rounded cell structure and polymorphic cells with pseudopodia of different lengths and shapes. SEM studies of the gills of AGD-affected Atlantic salmon, Salmo salar L., revealed the presence of enlarged swellings in affected gill filaments and fusion of adjacent lamellae. Spherical amoebae appeared to embed within the epithelium, and subsequently leave hemispherical indentations with visible fenestrations in the basolateral surface following their departure. These fenestrated structures corresponded to the presence of pseudopodia which could be seen by TEM to penetrate into the epithelium. The membrane-membrane interface contained an amorphous and slightly fibrous matrix. This suggests the existence of cellular glycocalyces and a role for extracellular products in mediating pathological changes in amoebic gill disease.
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Affiliation(s)
| | - T A Mo
- Norwegian Veterinary Institute, Oslo, Norway
| | - H Kolstad
- Imaging Centre, Norwegian University of Life Sciences, Ås, Norway
| | | | - S Hytterød
- Norwegian Veterinary Institute, Oslo, Norway
| | - M D Powell
- Norwegian Institute for Water Research, Bergen, Norway
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