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Andrea C. Alfaro - One of the best experts on this subject based on the ideXlab platform.
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Metabolomics investigation of summer mortality in New Zealand Greenshell™ mussels (Perna canaliculus).
Fish & shellfish immunology, 2020Co-Authors: Thao V. Nguyen, Andrea C. AlfaroAbstract:Abstract Increasing water temperatures due to climate change have resulted in more frequent high mortality events of New Zealand Greenshell™ mussels (Perna canaliculus Gmelin 1791). These events have significant impacts within mussel farms which support a major shellfish industry for New Zealand. The present study investigates metabolic responses of farmed mussels during a summer mortality event in order to identify health impacts and elucidate mechanistic effects of external stressors on mussels. A gas chromatography–mass spectrometry (GC–MS)-based metabolomics approach was used to identify metabolic perturbations and flow cytometry assays were used to assess viability, oxidative stress and apoptosis of haemocytes from healthy and unhealthy mussels during a summer mortality event. The results showed significantly higher mortality and apoptosis of haemocytes in unhealthy mussels compared to healthy mussels. Reactive oxygen species (ROS) production, which is an indicator of oxidative stress was very high in both mussel groups, but no differences were observed between the two mussel groups. Metabolomics revealed alterations of many metabolites in both haemolymph and hepatopancreas (digestive gland) of unhealthy mussels compared to healthy mussels, reflecting perturbations in several molecular pathways, including energy metabolism, amino acid metabolism, protein degradation/tissue damage and oxidative stress. An increased level of itaconic acid which is an antimicrobial metabolite and biomarker of pathogen infection was observed in haemolymph, but not in hepatopancreas samples. This investigation provides the first detailed metabolic characterization of mussel immune responses to a summer mortality event and illustrates the benefits of using an integrated metabolomics and flow cytometry workflow for mussel health assessment and biomarker identification for summer mortality early detection.
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Development stage of cryopreserved mussel (Perna canaliculus) larvae influences post-thaw impact on shell formation, organogenesis, neurogenesis, feeding ability and survival.
Cryobiology, 2020Co-Authors: Adam B. Rusk, Tim Young, Ellie Watts, Andrea C. Alfaro, Serean L. AdamsAbstract:Abstract Cryopreservation of genetic material from farmed aquatic species is a valuable technique to advance selective breeding programs for stock improvement. In this study, effects of cryopreservation on development of trochophore and D-stage larvae of Greenshell™ mussel (Perna canaliculus) were evaluated through histology, light microscopy, scanning electron microscopy, and confocal microscopy. Larvae of both life stages were motile immediately post-thawing, but survival declined rapidly from 4 days post-fertilisation (dpf). At 18 dpf, ~23% of non-cryopreserved control larvae had progressed to the pediveliger stage, while
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In vitro study of apoptosis in mussel (Perna canaliculus) haemocytes induced by lipopolysaccharide
Aquaculture, 2019Co-Authors: Thao V. Nguyen, Andrea C. Alfaro, Fabrice Merien, Tim YoungAbstract:Abstract Apoptosis or programmed cell death is a fundamental process essential for an organism's development and homeostasis in the immune system of both vertebrates and invertebrates. However, little is known about apoptotic processes in marine bivalves which require further investigation to elucidate mechanisms and identify molecular effectors of cell death pathways. In this study, we characterized cellular and molecular mechanisms of apoptosis induced by lipopolysaccharide (LPS) in New Zealand Greenshell™ mussel (Perna canaliculus) haemocytes. Mussel haemocyte samples were exposed to different LPS concentrations (0, 50 and 100 μg ml−1) and incubated at 19 °C for 3 h prior to assessment of various cell health parameters via flow cytometry assays and GC/MS-based metabolomic analyses. Flow cytometry results showed slightly higher, but non-significant differences in production of reactive oxygen species between LPS-exposed and control (no LPS) samples. However, percentages of apoptotic cells determined via depolarization of the mitochondrial membrane potential and caspase-3/7 activity in LPS-exposed samples were significantly higher than in control samples, providing mechanistic information regarding initiation and progression of the apoptotic cascade. The metabolite profile of LPS-exposed haemocytes showed elevated levels of 11 metabolites compared to that of the control. These metabolites may be involved in protein and lipid degradation as a consequence of apoptosis and other immune or physiological responses. This study demonstrates that LPS could trigger apoptosis in mussel haemocytes and provides insights into apoptotic processes in mussel haemocytes. Such knowledge could be useful for understanding the immune responses of farmed bivalves to waterborne pathogens and identification of molecular biomarkers for disease management in aquaculture.
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Tissue-specific immune responses to Vibrio sp. infection in mussels (Perna canaliculus): A metabolomics approach
Aquaculture, 2019Co-Authors: Thao V. Nguyen, Tim Young, Andrea C. Alfaro, Fabrice MerienAbstract:Abstract While tissue-specific immune responses are well-understood in mammals, such studies are lacking for marine bivalves. In this study, we investigated immune responses in gill, hepatopancreas and haemolymph of mussels (Perna canaliculus Gmelin, 1791) following experimental infection with Vibrio sp. DO1 (V. coralliilyticus/neptunius-like isolate). Significant differences in metabolite profiles and metabolic responses between tissues were observed. Overall, haemolymph and gills shared common metabolic responses characterized by increases in itaconic acid and decreases in other amino acids (e.g., BCAAs, lysine, tryptophan) and fatty acids (e.g., DHA, EPA, palmitoleic acid). Increases in itaconic acid, decreases in fatty acids, and increases in amino acids were found in hepatopancreas tissues. The alterations of these metabolites suggest osmotic stress, oxidative stress, changes in amino acid metabolism and protein synthesis in the immune system of P. canaliculus caused by Vibrio sp. infection. Interestingly, the accumulation of itaconic acid in all three tissues of infected mussels suggests that this metabolite has an important role in the mediation of bivalve antimicrobial activities and immune responses. These results indicate that careful consideration should be given to tissue sampling choices for immunological and metabolomics studies. In addition, further investigations are needed to elucidate mechanistic responses across different tissues associated with pathophysiological processes in bivalves.
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Copper-induced immunomodulation in mussel (Perna canaliculus) haemocytes.
Metallomics : integrated biometal science, 2018Co-Authors: Thao V. Nguyen, Andrea C. Alfaro, Fabrice Merien, Ronald Lulijwa, Tim YoungAbstract:Copper is a common contaminant in aquatic environments, which may cause physiological dysfunction in marine organisms. However, the toxicity mechanisms of copper in marine bivalves is not fully understood. In this study, we applied an integrated approach that combines flow cytometry and Gas Chromatography-Mass Spectrometry (GC-MS)-based metabolomics to characterize cellular and molecular mechanisms of copper immunotoxicity in New Zealand Greenshell™ mussel (Perna canaliculus) haemolymph. Flow cytometric results showed significant increases in haemocyte mortality, production of reactive oxygen species and apoptosis (via alteration of caspase 3/7 and mitochondrial membrane potential) of haemocytes exposed to increasing total concentrations of Cu2+ (62.5, 125.0 and 187.5 μM) compared to a low Cu2+ concentration (25.0 μM) and control (0.0 μM). In addition to flow cytometric data, our metabolomics results showed alterations of 25 metabolites within the metabolite profile of Cu2+-exposed haemolymph (125 μM) compared to those of control samples. Changes in levels of these metabolites may be considered important signatures of oxidative stress (e.g., glutathione) and apoptosis processes (e.g., alanine, glutamic acid). This study provides insights into the cellular and molecular mechanisms of oxidative stress and apoptosis in marine bivalves and highlights the applicability and reliability of metabolomic techniques for immunotoxicological studies in marine organisms.
Andrew Jeffs - One of the best experts on this subject based on the ideXlab platform.
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The value of EDTA treatment of hatchery water to rear Greenshell™ mussel (Perna canaliculus) larvae
Aquaculture International, 2020Co-Authors: Daniel R. Mcdougall, Norman L. C. Ragg, Andrew Jeffs, Julien Vignier, Bridget Finnie, Serean AdamsAbstract:The chelating agent ethylenediaminetetraacetic acid (EDTA) is used throughout the world to improve the yield of early stage D-larvae during bivalve hatchery production. Adding EDTA (12 μM) to seawater significantly increases the survival of Greenshell™ mussel ( Perna canaliculus ) larvae during their first 48 h of development. However, whether there are benefits of continuing to use EDTA beyond this first stage of larval development remain unknown and were tested in this study. After rearing for 48 h in the presence of EDTA, P. canaliculus larvae were experimentally raised to 22-day post-fertilisation in seawater with and without 12 μM EDTA. The survival, shell length growth, algal ingestion rate, swimming activity and potential toxic metal accumulation by the larvae were compared over this period. There were minimal benefits from continuing addition of EDTA. However, significant changes in metal concentrations within the larvae were observed. Zinc, cadmium and mercury were detected at significantly lower concentrations in 22-day-old larvae reared with EDTA versus those without EDTA. Collectively, the results indicate that the use of EDTA is critical only during the first 48 h of larval development, during which time larval shell formation is initiated and appears highly vulnerable to interference by heavy metal ions.
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Magnitude and timing of seed losses in mussel (Perna canaliculus) aquaculture
Aquaculture, 2020Co-Authors: Paul M. South, Oliver Floerl, Andrew JeffsAbstract:Abstract Losses of juvenile mussels seeded into aquaculture systems are a major constraint on the stability and growth of the New Zealand green-lipped mussel (Perna canaliculus) industry. Yet, the timing and magnitude of losses following seeding and during grow-out are unknown. In this study, losses of wild-sourced juvenile mussels were assessed 19, 40, and 89 days following deployment onto a mussel farm. In New Zealand, these wild juvenile mussels are attached to a variety of substrates, mostly macroalgae, hydroids or terrestrially derived material, when they are seeded into aquaculture systems. This study examined juvenile losses over time from coarse, fine and mixed macroalgae and unmanipulated substrate. Secondary settlement of mussels from their position at seeding to adjacent un-seeded sections of rope was followed to estimate migration. The number of dead mussels was quantified to assess the relative contributions of mortality and migration to mussel losses. In addition, small-scale variations in water quality that might be associated with the breakdown of the macroalgal substrates, such as dissolved oxygen and nutrient concentrations, were determined. Losses of mussels were initially very high (52.8–72.9% of the starting density at 19 days) and continued throughout the aquaculture nursery stage (40 days = 69.6–76.7%, 89 days = 74.4–84.9%). Overall retention was greatest for mussels deployed on coarse macroalgae (24.6%), but there were no consistent differences among substrates across deployment durations. At the end of the experiment, at least 20% of the estimated starting number of mussels had moved from their initial position at seeding. There were also high numbers (8.1% of the initial seeding density) of small dead mussels found soon after deployment. However, around 40% of the initial seeding density of juvenile mussels remained unaccounted for at the end of the experiment. These results highlight the immense scale of post-seeding losses in mussel aquaculture and the complexity of underlying processes driving these losses.
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Optimising environmental conditions for nursery culture of juvenile Greenshell™ mussels (Perna canaliculus)
Aquaculture, 2019Co-Authors: D. Sanjayasari, Andrew JeffsAbstract:Abstract The nursery culture of early juvenile bivalves is costly, requiring the provision of optimal environmental conditions for efficient production. Nursery production of mussels is particularly challenging because of their innate secondary settlement behaviour which can be triggered by unfavourable environmental conditions, resulting in mass migration of juveniles off aquaculture structures. This is a pronounced problem for the aquaculture of the Greeenshell™ mussel (Perna canaliculus) where losses of over 80% of juveniles are typical. Consequently, we examined the growth, survival and retention of juvenile mussels of this species in relation to four key environmental conditions (i.e., photoperiod, aeration, water flow, and oxygen levels) over 25 days in nursery holding conditions. Maintaining vigorous aeration and high dissolved oxygen (100%) both resulted in higher growth (126.1 and 89% respectively), survival (92.5 and 89% respectively) and retention (97.7 and 83.8% respectively). In contrast, photoperiod had minimal effect on juvenile mussel performance. This study suggests that providing suitable key environmental conditions has the potential to greatly improve the efficiency of production of P. canaliculus during commercial nursery aquaculture production.
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Understanding the ontogenetic changes in particle processing of the greenshell™ mussel, Perna canaliculus, in order to improve hatchery feeding practices
Aquaculture, 2016Co-Authors: Y. Gui, Brendon Dunphy, Leonardo N. Zamora, Andrew JeffsAbstract:Abstract Despite the commercial aquaculture importance of the Greenshell™ mussel, Perna canaliculus , the morphological development of gill structure (ctenidial filaments) in relation to potential particle feeding abilities have not been described. Scanning electron microscopy (SEM) and light microscopy were used to examine the ontogenetic changes across five size classes of mussels from post-settlement larvae to adults ranging from 300 μm to > 100 mm in shell height. Key morphological characteristics were measured including filament width, the eulatero-frontal cirri (ELF) length, interfilamentary space (IFS) and the mean distance between adjacent ELF, d ELF . Overall the development of the ctenidial filaments in P. canaliculus , shared some similarities to other homorhabdic filibranch bivalves with differences in the timing of development. Filament width and ELF length followed sigmoidal growth curves in relation to increasing shell height of mussels. The morphological changes of the ctenidia, reflected in changes in the ELF/IFS ratios, together with the development of cilia in the ELF may help explain the differences in the capture efficiency of small particles between small individuals ( Statement of relevance –This article provides information regarding the gill ontogenetic development of the commercially important Greenshell™ mussel, Perna canaliculus . –The information given will help improve hatchery practices, especially regarding the selection of adequate particle size for feeding post-settlement P. canaliculus . –Considering that mussel aquaculture is a global phenomenon, these results could be used worldwide in order to help the industry find economically feasible alternatives for mussel juvenile supply. The New Zealand Greenshell™ industry has recently invested $20 M to build a large scale hatchery/nursery to address an on-going shortage with seed supply which has been constraining the growth of the industry. Shortages of mussel seed, caused by poor feeding and starvation, have resulted in seed shortages in the industry for the last three years, shaving off almost 20% production of the entire industry, in the order of $30 M lost production a year. Hence there is intense interest in better understanding the feeding biology of juvenile mussels and using this knowledge to resolve the major production issues faced by this aquaculture industry. From our international contacts, we understand that other countries with significant mussel farming industries face similar issues, such as Chile. Therefore, we believe that there is strong reader interest and value in the publication of this fundamental research.
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Recruitment of the parasitic pea crab Nepinnotheres novaezelandiae into green-lipped mussels Perna canaliculus
Diseases of aquatic organisms, 2015Co-Authors: Oliver Trottier, Andrew JeffsAbstract:Pea crab species are globally ubiquitous parasites of marine bivalves including several major aquaculture species. However, little is known about the environmental factors that affect their recruitment into aquacultured mussels. The effect of depth and distance from shore on the recruitment of the parasitic pea crab Nepinnotheres novaezelandiae into New Zealand green-lipped mussels Perna canaliculus was examined with a field experiment. The incidence of pea crab infection of mussels over 295 d was nearly double when deployed at 5-10 m depth (1.97%) compared to 20-30 m depth (0.96%), although it was not significantly different due to the overall low period prevalence in the experimental population. The sex ratio of crabs recovered was significantly skewed towards females with a ratio of 1:14 (χ = 11.3, p < 0.001). Infection with pea crabs was found to significantly reduce final mussel shell height on average by 28% (21.0 mm) over 295 d (Mann-Whitney U = 6.0, p < 0.0001). This study confirms that parasitism of green-lipped mussels by pea crabs has a significant impact on the growth of the mussels and suggests that the incidence of pea crabs will be higher in shallower water and when mussels are in closer proximity to the shore. With no control methods available for preventing pea crab infection, these results suggest that moving mussel farms offshore has the potential to reduce the incidence of pea crabs in mussels and warrants larger-scale assessment.
Tim Young - One of the best experts on this subject based on the ideXlab platform.
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Development stage of cryopreserved mussel (Perna canaliculus) larvae influences post-thaw impact on shell formation, organogenesis, neurogenesis, feeding ability and survival.
Cryobiology, 2020Co-Authors: Adam B. Rusk, Tim Young, Ellie Watts, Andrea C. Alfaro, Serean L. AdamsAbstract:Abstract Cryopreservation of genetic material from farmed aquatic species is a valuable technique to advance selective breeding programs for stock improvement. In this study, effects of cryopreservation on development of trochophore and D-stage larvae of Greenshell™ mussel (Perna canaliculus) were evaluated through histology, light microscopy, scanning electron microscopy, and confocal microscopy. Larvae of both life stages were motile immediately post-thawing, but survival declined rapidly from 4 days post-fertilisation (dpf). At 18 dpf, ~23% of non-cryopreserved control larvae had progressed to the pediveliger stage, while
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The Effects of Aragonite Saturation State on Hatchery-Reared Larvae of the Greenshell Mussel Perna canaliculus
Journal of Shellfish Research, 2019Co-Authors: Norman L. C. Ragg, Zoë Hilton, Samantha L. Gale, Nicola A. Hawes, David J. Burritt, Tim Young, Jessica A. Ericson, Ellie Watts, Jolene BerryAbstract:The major cultured mussel species Perna canaliculus is now supported by hatchery production, providing the opportunity to explore and optimize environmental parameters to enhance production. Other cultured bivalve larvae have demonstrated performance that is directly correlated to the aragonite saturation state (Ωar) of their tank water, with low or undersaturated water being detrimental and artificially elevated Ωar enhancing productivity. Trials were, therefore, designed to specifically explore Ωar sensitivity in preveliger (0–2 days old, prodissoconch I = “PD1″) and veliger (2–21 days old, prodissoconch II = “PD2″) stages of P. canaliculus separately. For the PD1 experiment, commercial incubation tanks (control Ωar 1.9) were modified to target Ωar 0.5 or 0.8 by elevating pCO2, or 2.9, 4.5, and ∼7 by the addition of sodium carbonate. In the control environment, 72.8% ± 2.9% of fertilized eggs formed viable “D” veligers within two days; an increased yield of 82.6% ± 3.8% in Ωar 4.5 was found to be nonsignificant. In comparison, only 12.7% of the Ωar ∼7 and
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Tissue-specific immune responses to Vibrio sp. infection in mussels (Perna canaliculus): A metabolomics approach
Aquaculture, 2019Co-Authors: Thao V. Nguyen, Tim Young, Andrea C. Alfaro, Fabrice MerienAbstract:Abstract While tissue-specific immune responses are well-understood in mammals, such studies are lacking for marine bivalves. In this study, we investigated immune responses in gill, hepatopancreas and haemolymph of mussels (Perna canaliculus Gmelin, 1791) following experimental infection with Vibrio sp. DO1 (V. coralliilyticus/neptunius-like isolate). Significant differences in metabolite profiles and metabolic responses between tissues were observed. Overall, haemolymph and gills shared common metabolic responses characterized by increases in itaconic acid and decreases in other amino acids (e.g., BCAAs, lysine, tryptophan) and fatty acids (e.g., DHA, EPA, palmitoleic acid). Increases in itaconic acid, decreases in fatty acids, and increases in amino acids were found in hepatopancreas tissues. The alterations of these metabolites suggest osmotic stress, oxidative stress, changes in amino acid metabolism and protein synthesis in the immune system of P. canaliculus caused by Vibrio sp. infection. Interestingly, the accumulation of itaconic acid in all three tissues of infected mussels suggests that this metabolite has an important role in the mediation of bivalve antimicrobial activities and immune responses. These results indicate that careful consideration should be given to tissue sampling choices for immunological and metabolomics studies. In addition, further investigations are needed to elucidate mechanistic responses across different tissues associated with pathophysiological processes in bivalves.
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In vitro study of apoptosis in mussel (Perna canaliculus) haemocytes induced by lipopolysaccharide
Aquaculture, 2019Co-Authors: Thao V. Nguyen, Andrea C. Alfaro, Fabrice Merien, Tim YoungAbstract:Abstract Apoptosis or programmed cell death is a fundamental process essential for an organism's development and homeostasis in the immune system of both vertebrates and invertebrates. However, little is known about apoptotic processes in marine bivalves which require further investigation to elucidate mechanisms and identify molecular effectors of cell death pathways. In this study, we characterized cellular and molecular mechanisms of apoptosis induced by lipopolysaccharide (LPS) in New Zealand Greenshell™ mussel (Perna canaliculus) haemocytes. Mussel haemocyte samples were exposed to different LPS concentrations (0, 50 and 100 μg ml−1) and incubated at 19 °C for 3 h prior to assessment of various cell health parameters via flow cytometry assays and GC/MS-based metabolomic analyses. Flow cytometry results showed slightly higher, but non-significant differences in production of reactive oxygen species between LPS-exposed and control (no LPS) samples. However, percentages of apoptotic cells determined via depolarization of the mitochondrial membrane potential and caspase-3/7 activity in LPS-exposed samples were significantly higher than in control samples, providing mechanistic information regarding initiation and progression of the apoptotic cascade. The metabolite profile of LPS-exposed haemocytes showed elevated levels of 11 metabolites compared to that of the control. These metabolites may be involved in protein and lipid degradation as a consequence of apoptosis and other immune or physiological responses. This study demonstrates that LPS could trigger apoptosis in mussel haemocytes and provides insights into apoptotic processes in mussel haemocytes. Such knowledge could be useful for understanding the immune responses of farmed bivalves to waterborne pathogens and identification of molecular biomarkers for disease management in aquaculture.
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Copper-induced immunomodulation in mussel (Perna canaliculus) haemocytes.
Metallomics : integrated biometal science, 2018Co-Authors: Thao V. Nguyen, Andrea C. Alfaro, Fabrice Merien, Ronald Lulijwa, Tim YoungAbstract:Copper is a common contaminant in aquatic environments, which may cause physiological dysfunction in marine organisms. However, the toxicity mechanisms of copper in marine bivalves is not fully understood. In this study, we applied an integrated approach that combines flow cytometry and Gas Chromatography-Mass Spectrometry (GC-MS)-based metabolomics to characterize cellular and molecular mechanisms of copper immunotoxicity in New Zealand Greenshell™ mussel (Perna canaliculus) haemolymph. Flow cytometric results showed significant increases in haemocyte mortality, production of reactive oxygen species and apoptosis (via alteration of caspase 3/7 and mitochondrial membrane potential) of haemocytes exposed to increasing total concentrations of Cu2+ (62.5, 125.0 and 187.5 μM) compared to a low Cu2+ concentration (25.0 μM) and control (0.0 μM). In addition to flow cytometric data, our metabolomics results showed alterations of 25 metabolites within the metabolite profile of Cu2+-exposed haemolymph (125 μM) compared to those of control samples. Changes in levels of these metabolites may be considered important signatures of oxidative stress (e.g., glutathione) and apoptosis processes (e.g., alanine, glutamic acid). This study provides insights into the cellular and molecular mechanisms of oxidative stress and apoptosis in marine bivalves and highlights the applicability and reliability of metabolomic techniques for immunotoxicological studies in marine organisms.
Thao V. Nguyen - One of the best experts on this subject based on the ideXlab platform.
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Metabolomics investigation of summer mortality in New Zealand Greenshell™ mussels (Perna canaliculus).
Fish & shellfish immunology, 2020Co-Authors: Thao V. Nguyen, Andrea C. AlfaroAbstract:Abstract Increasing water temperatures due to climate change have resulted in more frequent high mortality events of New Zealand Greenshell™ mussels (Perna canaliculus Gmelin 1791). These events have significant impacts within mussel farms which support a major shellfish industry for New Zealand. The present study investigates metabolic responses of farmed mussels during a summer mortality event in order to identify health impacts and elucidate mechanistic effects of external stressors on mussels. A gas chromatography–mass spectrometry (GC–MS)-based metabolomics approach was used to identify metabolic perturbations and flow cytometry assays were used to assess viability, oxidative stress and apoptosis of haemocytes from healthy and unhealthy mussels during a summer mortality event. The results showed significantly higher mortality and apoptosis of haemocytes in unhealthy mussels compared to healthy mussels. Reactive oxygen species (ROS) production, which is an indicator of oxidative stress was very high in both mussel groups, but no differences were observed between the two mussel groups. Metabolomics revealed alterations of many metabolites in both haemolymph and hepatopancreas (digestive gland) of unhealthy mussels compared to healthy mussels, reflecting perturbations in several molecular pathways, including energy metabolism, amino acid metabolism, protein degradation/tissue damage and oxidative stress. An increased level of itaconic acid which is an antimicrobial metabolite and biomarker of pathogen infection was observed in haemolymph, but not in hepatopancreas samples. This investigation provides the first detailed metabolic characterization of mussel immune responses to a summer mortality event and illustrates the benefits of using an integrated metabolomics and flow cytometry workflow for mussel health assessment and biomarker identification for summer mortality early detection.
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Tissue-specific immune responses to Vibrio sp. infection in mussels (Perna canaliculus): A metabolomics approach
Aquaculture, 2019Co-Authors: Thao V. Nguyen, Tim Young, Andrea C. Alfaro, Fabrice MerienAbstract:Abstract While tissue-specific immune responses are well-understood in mammals, such studies are lacking for marine bivalves. In this study, we investigated immune responses in gill, hepatopancreas and haemolymph of mussels (Perna canaliculus Gmelin, 1791) following experimental infection with Vibrio sp. DO1 (V. coralliilyticus/neptunius-like isolate). Significant differences in metabolite profiles and metabolic responses between tissues were observed. Overall, haemolymph and gills shared common metabolic responses characterized by increases in itaconic acid and decreases in other amino acids (e.g., BCAAs, lysine, tryptophan) and fatty acids (e.g., DHA, EPA, palmitoleic acid). Increases in itaconic acid, decreases in fatty acids, and increases in amino acids were found in hepatopancreas tissues. The alterations of these metabolites suggest osmotic stress, oxidative stress, changes in amino acid metabolism and protein synthesis in the immune system of P. canaliculus caused by Vibrio sp. infection. Interestingly, the accumulation of itaconic acid in all three tissues of infected mussels suggests that this metabolite has an important role in the mediation of bivalve antimicrobial activities and immune responses. These results indicate that careful consideration should be given to tissue sampling choices for immunological and metabolomics studies. In addition, further investigations are needed to elucidate mechanistic responses across different tissues associated with pathophysiological processes in bivalves.
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In vitro study of apoptosis in mussel (Perna canaliculus) haemocytes induced by lipopolysaccharide
Aquaculture, 2019Co-Authors: Thao V. Nguyen, Andrea C. Alfaro, Fabrice Merien, Tim YoungAbstract:Abstract Apoptosis or programmed cell death is a fundamental process essential for an organism's development and homeostasis in the immune system of both vertebrates and invertebrates. However, little is known about apoptotic processes in marine bivalves which require further investigation to elucidate mechanisms and identify molecular effectors of cell death pathways. In this study, we characterized cellular and molecular mechanisms of apoptosis induced by lipopolysaccharide (LPS) in New Zealand Greenshell™ mussel (Perna canaliculus) haemocytes. Mussel haemocyte samples were exposed to different LPS concentrations (0, 50 and 100 μg ml−1) and incubated at 19 °C for 3 h prior to assessment of various cell health parameters via flow cytometry assays and GC/MS-based metabolomic analyses. Flow cytometry results showed slightly higher, but non-significant differences in production of reactive oxygen species between LPS-exposed and control (no LPS) samples. However, percentages of apoptotic cells determined via depolarization of the mitochondrial membrane potential and caspase-3/7 activity in LPS-exposed samples were significantly higher than in control samples, providing mechanistic information regarding initiation and progression of the apoptotic cascade. The metabolite profile of LPS-exposed haemocytes showed elevated levels of 11 metabolites compared to that of the control. These metabolites may be involved in protein and lipid degradation as a consequence of apoptosis and other immune or physiological responses. This study demonstrates that LPS could trigger apoptosis in mussel haemocytes and provides insights into apoptotic processes in mussel haemocytes. Such knowledge could be useful for understanding the immune responses of farmed bivalves to waterborne pathogens and identification of molecular biomarkers for disease management in aquaculture.
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Copper-induced immunomodulation in mussel (Perna canaliculus) haemocytes.
Metallomics : integrated biometal science, 2018Co-Authors: Thao V. Nguyen, Andrea C. Alfaro, Fabrice Merien, Ronald Lulijwa, Tim YoungAbstract:Copper is a common contaminant in aquatic environments, which may cause physiological dysfunction in marine organisms. However, the toxicity mechanisms of copper in marine bivalves is not fully understood. In this study, we applied an integrated approach that combines flow cytometry and Gas Chromatography-Mass Spectrometry (GC-MS)-based metabolomics to characterize cellular and molecular mechanisms of copper immunotoxicity in New Zealand Greenshell™ mussel (Perna canaliculus) haemolymph. Flow cytometric results showed significant increases in haemocyte mortality, production of reactive oxygen species and apoptosis (via alteration of caspase 3/7 and mitochondrial membrane potential) of haemocytes exposed to increasing total concentrations of Cu2+ (62.5, 125.0 and 187.5 μM) compared to a low Cu2+ concentration (25.0 μM) and control (0.0 μM). In addition to flow cytometric data, our metabolomics results showed alterations of 25 metabolites within the metabolite profile of Cu2+-exposed haemolymph (125 μM) compared to those of control samples. Changes in levels of these metabolites may be considered important signatures of oxidative stress (e.g., glutathione) and apoptosis processes (e.g., alanine, glutamic acid). This study provides insights into the cellular and molecular mechanisms of oxidative stress and apoptosis in marine bivalves and highlights the applicability and reliability of metabolomic techniques for immunotoxicological studies in marine organisms.
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metabolomics study of immune responses of new zealand greenshell mussels Perna canaliculus infected with pathogenic vibrio sp
Marine Biotechnology, 2018Co-Authors: Thao V. Nguyen, Tim Young, Andrea C. Alfaro, Sridevi Ravi, Fabrice MerienAbstract:Vibrio coralliilyticus is a bacterial pathogen which can affect a range of marine organisms, such as corals, fish and shellfish, with sometimes devastating consequences. However, little is known about the mechanisms involved in the host-pathogen interaction, especially within molluscan models. We applied gas chromatography-mass spectrometry (GC-MS)-based metabolomics to characterize the physiological responses in haemolymph of New Zealand Greenshell™ mussels (Perna canaliculus) injected with Vibrio sp. DO1 (V. coralliilyticus/neptunius-like isolate). Univariate data analyses of metabolite profiles in Vibrio-exposed mussels revealed significant changes in 22 metabolites at 6 h post-infection, compared to non-exposed mussels. Among them, 10 metabolites were up-regulated, while 12 metabolites were down-regulated in infected mussels. Multivariate analyses showed a clear distinction between infected and non-infected mussels. In addition, secondary pathway analyses indicated perturbations of the host innate immune system following infection, including oxidative stress, inflammation and disruption of the TCA cycle, change in amino acid metabolism and protein synthesis. These findings provide new insights into the pathogenic mechanisms of Vibrio infection of mussels and demonstrate our ability to detect detailed and rapid host responses from haemolymph samples using a metabolomics approach.
Fabrice Merien - One of the best experts on this subject based on the ideXlab platform.
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Tissue-specific immune responses to Vibrio sp. infection in mussels (Perna canaliculus): A metabolomics approach
Aquaculture, 2019Co-Authors: Thao V. Nguyen, Tim Young, Andrea C. Alfaro, Fabrice MerienAbstract:Abstract While tissue-specific immune responses are well-understood in mammals, such studies are lacking for marine bivalves. In this study, we investigated immune responses in gill, hepatopancreas and haemolymph of mussels (Perna canaliculus Gmelin, 1791) following experimental infection with Vibrio sp. DO1 (V. coralliilyticus/neptunius-like isolate). Significant differences in metabolite profiles and metabolic responses between tissues were observed. Overall, haemolymph and gills shared common metabolic responses characterized by increases in itaconic acid and decreases in other amino acids (e.g., BCAAs, lysine, tryptophan) and fatty acids (e.g., DHA, EPA, palmitoleic acid). Increases in itaconic acid, decreases in fatty acids, and increases in amino acids were found in hepatopancreas tissues. The alterations of these metabolites suggest osmotic stress, oxidative stress, changes in amino acid metabolism and protein synthesis in the immune system of P. canaliculus caused by Vibrio sp. infection. Interestingly, the accumulation of itaconic acid in all three tissues of infected mussels suggests that this metabolite has an important role in the mediation of bivalve antimicrobial activities and immune responses. These results indicate that careful consideration should be given to tissue sampling choices for immunological and metabolomics studies. In addition, further investigations are needed to elucidate mechanistic responses across different tissues associated with pathophysiological processes in bivalves.
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In vitro study of apoptosis in mussel (Perna canaliculus) haemocytes induced by lipopolysaccharide
Aquaculture, 2019Co-Authors: Thao V. Nguyen, Andrea C. Alfaro, Fabrice Merien, Tim YoungAbstract:Abstract Apoptosis or programmed cell death is a fundamental process essential for an organism's development and homeostasis in the immune system of both vertebrates and invertebrates. However, little is known about apoptotic processes in marine bivalves which require further investigation to elucidate mechanisms and identify molecular effectors of cell death pathways. In this study, we characterized cellular and molecular mechanisms of apoptosis induced by lipopolysaccharide (LPS) in New Zealand Greenshell™ mussel (Perna canaliculus) haemocytes. Mussel haemocyte samples were exposed to different LPS concentrations (0, 50 and 100 μg ml−1) and incubated at 19 °C for 3 h prior to assessment of various cell health parameters via flow cytometry assays and GC/MS-based metabolomic analyses. Flow cytometry results showed slightly higher, but non-significant differences in production of reactive oxygen species between LPS-exposed and control (no LPS) samples. However, percentages of apoptotic cells determined via depolarization of the mitochondrial membrane potential and caspase-3/7 activity in LPS-exposed samples were significantly higher than in control samples, providing mechanistic information regarding initiation and progression of the apoptotic cascade. The metabolite profile of LPS-exposed haemocytes showed elevated levels of 11 metabolites compared to that of the control. These metabolites may be involved in protein and lipid degradation as a consequence of apoptosis and other immune or physiological responses. This study demonstrates that LPS could trigger apoptosis in mussel haemocytes and provides insights into apoptotic processes in mussel haemocytes. Such knowledge could be useful for understanding the immune responses of farmed bivalves to waterborne pathogens and identification of molecular biomarkers for disease management in aquaculture.
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Copper-induced immunomodulation in mussel (Perna canaliculus) haemocytes.
Metallomics : integrated biometal science, 2018Co-Authors: Thao V. Nguyen, Andrea C. Alfaro, Fabrice Merien, Ronald Lulijwa, Tim YoungAbstract:Copper is a common contaminant in aquatic environments, which may cause physiological dysfunction in marine organisms. However, the toxicity mechanisms of copper in marine bivalves is not fully understood. In this study, we applied an integrated approach that combines flow cytometry and Gas Chromatography-Mass Spectrometry (GC-MS)-based metabolomics to characterize cellular and molecular mechanisms of copper immunotoxicity in New Zealand Greenshell™ mussel (Perna canaliculus) haemolymph. Flow cytometric results showed significant increases in haemocyte mortality, production of reactive oxygen species and apoptosis (via alteration of caspase 3/7 and mitochondrial membrane potential) of haemocytes exposed to increasing total concentrations of Cu2+ (62.5, 125.0 and 187.5 μM) compared to a low Cu2+ concentration (25.0 μM) and control (0.0 μM). In addition to flow cytometric data, our metabolomics results showed alterations of 25 metabolites within the metabolite profile of Cu2+-exposed haemolymph (125 μM) compared to those of control samples. Changes in levels of these metabolites may be considered important signatures of oxidative stress (e.g., glutathione) and apoptosis processes (e.g., alanine, glutamic acid). This study provides insights into the cellular and molecular mechanisms of oxidative stress and apoptosis in marine bivalves and highlights the applicability and reliability of metabolomic techniques for immunotoxicological studies in marine organisms.
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metabolomics study of immune responses of new zealand greenshell mussels Perna canaliculus infected with pathogenic vibrio sp
Marine Biotechnology, 2018Co-Authors: Thao V. Nguyen, Tim Young, Andrea C. Alfaro, Sridevi Ravi, Fabrice MerienAbstract:Vibrio coralliilyticus is a bacterial pathogen which can affect a range of marine organisms, such as corals, fish and shellfish, with sometimes devastating consequences. However, little is known about the mechanisms involved in the host-pathogen interaction, especially within molluscan models. We applied gas chromatography-mass spectrometry (GC-MS)-based metabolomics to characterize the physiological responses in haemolymph of New Zealand Greenshell™ mussels (Perna canaliculus) injected with Vibrio sp. DO1 (V. coralliilyticus/neptunius-like isolate). Univariate data analyses of metabolite profiles in Vibrio-exposed mussels revealed significant changes in 22 metabolites at 6 h post-infection, compared to non-exposed mussels. Among them, 10 metabolites were up-regulated, while 12 metabolites were down-regulated in infected mussels. Multivariate analyses showed a clear distinction between infected and non-infected mussels. In addition, secondary pathway analyses indicated perturbations of the host innate immune system following infection, including oxidative stress, inflammation and disruption of the TCA cycle, change in amino acid metabolism and protein synthesis. These findings provide new insights into the pathogenic mechanisms of Vibrio infection of mussels and demonstrate our ability to detect detailed and rapid host responses from haemolymph samples using a metabolomics approach.