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Wayne A Oconnor - One of the best experts on this subject based on the ideXlab platform.
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dynamics of the sydney Rock Oyster microbiota before and during a qx disease event
Aquaculture, 2021Co-Authors: Viet Khue Nguyen, Wayne A Oconnor, Michael Dove, William L King, Nachshon Siboni, Khandaker Rayhan Mahbub, Justin R Seymour, Hafizur Rahman, Cheryl Jenkins, Maurizio LabbateAbstract:Abstract The Sydney Rock Oyster (SRO; Saccostrea glomerata) is the most intensively farmed Oyster species in Australia however, Queensland unknown (QX) disease has resulted in substantial losses and impeded productivity. QX disease is caused by infection with the parasite Marteilia sydneyi, and like other diseases, outbreaks are driven by a series of complex environmental and host factors such as seasonality, seawater salinity and Oyster genetics. A potential but understudied factor in QX disease is the SRO microbiota, which we sought to examine before and during a QX disease outbreak. Using 16S rRNA (V1 – V3 region) amplicon sequencing, we examined the microbiota of SROs deployed in an estuary where QX disease occurs, with sampling conducted fortnightly over 22 weeks. Marteilia sydneyi was detected in the SROs by PCR (QX-positive), 16 weeks after the first sampling event and sporonts were observed in the digestive gland two weeks later on. There were no apparent patterns observed between the microbiota of QX-positive SROs with and without digestive gland sporonts however, the microbiota of QX-positive SROs was significantly different from those sampled prior to detection of M. sydneyi and from those negative for M. sydneyi post detection. As a result, shifts in microbiota structure occurred before sporulation in the digestive gland and either before or shortly after pathogen colonisation. The microbiota shifts associated with QX-positive Oysters were principally driven by a relative abundance increase of operational taxonomic units (OTUs) assigned to unclassified species of the Borrelia and Candidatus Hepatoplasma genera and a relative abundance decrease in an OTU assigned to an unclassified species of the Mycoplasma genus. Since Mycoplasma species are common microbiota features of SROs and other Oysters, we propose that there may be an important ecological link between Mycoplasma species and the health state of SROs.
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the sydney Rock Oyster microbiota is influenced by location season and genetics
Aquaculture, 2020Co-Authors: Viet Khue Nguyen, Wayne A Oconnor, Michael Dove, William L King, Nachshon Siboni, Khandaker Rayhan Mahbub, Justin R Seymour, Maurizio LabbateAbstract:Abstract Queensland unknown (QX) disease is a significant cause of economic loss for the Sydney Rock Oyster (SRO) aquaculture industry. Evidence is emerging that QX disease is multi-factorial in nature, with a number of environmental and host factors contributing to disease dynamics. Efforts to mitigate the impacts of QX disease are primarily focused on breeding for disease resistance however, the mechanisms that drive disease resistance are poorly understood. One potential factor influencing disease resistance is the microbiota. To determine the influence of location, season and disease resistance on the SRO microbiota, we used 16S rRNA (V1 – V3 region) amplicon sequencing. The microbiota of six SRO families with two categorised as QX-resistant and four as QX-susceptible, deployed to two different locations (Port Stephens and Wallis Lake, NSW, Australia) and over two seasons (Austral summer and winter), were characterised. As expected, the SRO microbiota was distinct to the microbial community found in seawater. Further, the SRO microbiota was significantly influenced by location and season, with operational taxonomic units (OTUs) assigned to the Candidatus Hepatoplasma and Endozoicomonas genera identified as significant drivers of microbiota dissimilarity between locations and seasons. Disease resistance also significantly influenced the SRO microbiota but only at the winter time point which is before the typical QX disease period. Overall, OTUs assigned to the Mycoplasma, Borrelia and Endozoicomonas genera were over-represented in QX-resistant SRO microbiota, whereas members of the Pseudoalteromonas, Vibrio, and Candidatus Hepatoplasma genera were over-represented in QX-sensitive microbiota. These findings confirm the influencing role of location and season on the microbiota structure as evidenced in other molluscan species, but also provide preliminary evidence that the microbiota assemblage before the QX disease period may be important for resistance to disease and may provide new avenues for managing SRO aquaculture in the future.
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bioavailability of polycyclic aromatic compounds pacs to the sydney Rock Oyster saccostrea glomerata from sediment matrices of an economically important australian estuary
Science of The Total Environment, 2020Co-Authors: Oluyoye Idowu, Wayne A Oconnor, Thi Kim Anh Tran, Phil Baker, Hazel Farrel, Anthony Zammit, Kirk T Semple, Palanisami ThavamaniAbstract:Improving risk assessment and remediation rests on better understanding of contaminant bioavailability. Despite their strong toxicological attributes, little is known about the partitioning behaviour and bioavailability of polar polycyclic aromatic hydrocarbons (PAHs) in aquatic environments. The present study provides an insight into the bioavailable fractions of polar PAHs and their parent analogues in the tissues of the Sydney Rock Oyster, Saccostrea glomerata, a model aquatic bio-indicator organism. The concentration and distribution patterns of parent and polar PAHs including oxygenated PAHs (oxyPAHs), nitrated PAHs (NPAHs) and heterocyclic PAHs (HPAHs) were determined in water, sediment and Oysters from an ecologically and economically important estuary of New South Wales, Australia. Total concentrations of PAHs, oxyPAHs, NPAHs and HPAHs were higher in sediments compared to Oyster tissue and water. For most polar PAHs, total concentrations for water, sediment and Oyster samples were 1). BSAF individual computation showed that bioaccumulation of nine investigated HPAHs in Oyster tissues were relatively low and only 2-EAQ (oxyPAH) and 1N-NAP (NPAH) showed high levels of accumulation in Oyster tissues, similar to parent PAHs. To the best of our knowledge, this is the first known study on the bioavailability of polar and non-polar PAHs in an Australian aquatic environment. The outcome of this study might be a useful indicator of the potential risks of polar PAHs to humans and other living organisms.
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parental exposure to the synthetic estrogen 17α ethinylestradiol ee2 affects offspring development in the sydney Rock Oyster saccostrea glomerata
Environmental Pollution, 2020Co-Authors: Rafiquel Islam, Wayne A Oconnor, Thi Kim Anh Tran, Megan Andrewpriestley, Frederic D L Leusch, Geoff R MacfarlaneAbstract:Very little is currently known regarding the effects of estrogenic endocrine disrupting chemicals on embryonic and larval development in molluscs, nor the potential effects of parental (F0) exposure on resultant F1 offspring. In this study, we assessed the embryotoxic impacts of exposure to environmentally relevant concentrations of the synthetic estrogen, 17α-ethinylestradiol (EE2), to male and female parents (50 ng/L) and their offspring (5 and 50 ng/L) in the native Australian Sydney Rock Oyster, Saccostrea glomerata. There were no detectable effects of parental exposure on fertilisation success, proportions of early larval (F1) morphs and unfertilised eggs. Offspring impacts were evidenced in terms of developmental delays, with decreased percentages of D-veligers retained by 45 μm mesh, along with a reduction of swimming capabilities of larvae at 2 days post-fertilisation (dpf) when both parents had been exposed to 50 ng/L EE2. Although no significant parental effects were found on the survival of F1 larvae at 9 dpf, retardation of shell growth was observed on F1 larvae in treatments where both parents had been exposed to 50 ng/L EE2. Subsequent larval exposure from 2 to 9 dpf caused declines in survival and reduction of shell length in F1 larvae at both 5 and 50 ng/L EE2 across all parental exposure treatments. Collectively, parental EE2 imparts effects on offspring in terms of retardation of larval development, and subsequent offspring exposure to EE2 further exacerbates impacts to development. Future research should aim to understand the potential mechanisms of EE2 induced toxicity and its transmission resulting in altered phenotypes of the F1 generation.
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characterisation of the metallothionein gene in the sydney Rock Oyster and its expression upon metal exposure in Oysters with different prior metal exposure histories
Marine Environmental Research, 2019Co-Authors: Thanvapon Yingprasertchai, Wayne A Oconnor, Thi Kim Anh Tran, Richard Y C Kong, Geoff R MacfarlaneAbstract:The metal-binding protein metallothionein (MT) is widely used as a biomarker of metal contamination. In this study, we cloned a MT gene (sgMT) from the Sydney Rock Oyster Saccostrea glomerata. The gene encodes a MT-I protein with a classical αβ domain structure and is expressed as two transcripts resulting from alternative polyadenylation. The gene promoter contains two putative metal-responsive elements (MREs) which are known to be required for metal-inducible transcription. A specific and efficient qPCR assay was developed to quantify sgMT mRNA expression. Further, we assessed whether prior metal exposure history influences sgMT mRNA expression upon subsequent metal exposure. Oysters with varying prior metal exposure histories (contaminated and reference) were exposed to Cu, Cd and Zn. Expression of sgMT generally increased with metal dose, and Oysters with an elevated past metal exposure history exhibited higher sgMT expression under Cd and Zn stress, representing a potential acclimatory response to prior metal exposure.
John A. Nell - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the progeny of the fourth generation sydney Rock Oyster saccostrea glomerata gould 1850 breeding lines for resistance to qx disease marteilia sydneyi and winter mortality bonamia roughleyi
Aquaculture Research, 2006Co-Authors: Michael Dove, John A. Nell, Wayne A OconnorAbstract:A breeding program for Sydney Rock Oysters Saccostrea glomerata (Gould, 1850) has been selecting Oysters for resistance to QX disease (Marteilia sydneyi) and winter mortality (Bonamia roughleyi) for three generations at three sites in Georges River, New South Wales, Australia. The experimental sites are located at the upper, middle and lower reaches of Oyster growing areas in the estuary. QX disease mainly occurs in the middle and upper reaches and is most severe at the latter. Winter mortality on the other hand occurs mainly at the lower and middle reaches and is most severe at the former. Progeny of third-generation Sydney Rock Oyster breeding lines were evaluated for resistance to both QX disease and winter mortality against a non-selected control. Line 1, selected for QX disease resistance at the upper estuary site, had excellent resistance to one season of exposure to disease, but suffered high mortality during the second season of exposure. However, these Oysters had already reached market size of 50 g whole weight, with low mortality at 2 years of age, before the second episode of QX disease. Line 2 showed good improvement in resistance to both diseases, whereas Line 3, was the most resistant to winter mortality. Selection for resistance to QX disease did not appear to confer resistance to winter mortality and the converse also applied.
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Evaluation of progeny of fourth generation Sydney Rock Oyster Saccostrea glomerata (Gould, 1850) breeding lines
Aquaculture Research, 2005Co-Authors: John A. Nell, Ben PerkinsAbstract:The progeny of four 4th generation Sydney Rock Oyster Saccostrea glomerata (Gould, 1850) breeding lines that were selected for fast growth were compared in a 3-year farming experiment. Oysters of the most improved breeding line (line 2) reached market size (≥50-g whole weight) 15 months earlier than non-selected control Oysters (3 years and 5 months). The average reduction in time to market size for Oysters of all four breeding lines was 12.5 months.
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evaluation of the progeny of second generation sydney Rock Oyster saccostrea glomerata gould 1850 breeding lines for resistance to qx disease marteilia sydneyi
Aquaculture, 2003Co-Authors: John A. Nell, Rosalind E. HandAbstract:Abstract The progeny of second-generation Sydney Rock Oyster Saccostrea glomerata (Gould, 1850) breeding lines were tested for resistance to QX disease Marteilia sydneyi against a non-selected control. Mortality was reduced from 85.7±1.5% for the controls to 63.5±1.2% for the most improved breeding line. This is a reduction in mortality of 22% after only two generations of selection. These partially QX disease-resistant Oysters in which M. sydneyi was found were also 21% heavier than controls. Selection for resistance to M. sydneyi is feasible and may be improved through further selection.
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Food value of live yeasts and dry yeast-based diets fed to Sydney Rock Oyster Saccostrea commercialis spat
Aquaculture, 1996Co-Authors: John A. Nell, John A. Diemar, Mike HeasmanAbstract:Abstract Six yeast species, cultured on both glucose and acetate as carbon sources, and three dry yeast-based diets (Microfeast ® ) were compared as potential algae substitutes for feeding Sydney Rock Oyster spat. At the 80% substitution level, two of the dry yeast-based diets containing 7.6 and 21.5% total lipid gave 72 and 76%, respectively, of the dry spat weight gain obtained with the algae-fed control. Weight gains of 58–67% of that of the algae-fed control were also obtained with the following live yeast diets: Dipodascus capitatus and Candida utilis cultured on either glucose or acetate, and Saccharomyces cerevisiae cultured on glucose. There was a negative correlation between the increase in spat dry weight and nitrogen free extract ( r = −0.58; y = 30.34 − 0.26 x ; P r = 0.51; y = 6.10 + 0.31 x ; P
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the effect of bis tributyltin oxide tbto and copper on the growth of juvenile sydney Rock Oysters saccostrea commercialis iredale and roughley and pacific Oysters crassostrea gigas thunberg
Science of The Total Environment, 1992Co-Authors: John A. Nell, Ramon ChvojkaAbstract:The growth of juvenile (spat) (1.25–2.62 mg dry wt) Pacific Oysters C. gigas and Sydney Rock Oysters S. commercialis was reduced by only 5 ng bis-tributyltin oxide (TBTO) l−1 seawater. The reduction in growth of the Pacific Oysters was more severe than that of the Sydney Rock Oysters. When Sydney Rock Oyster spat were exposed to both copper and TBTO they suffered a greater reduction in growth than those exposed to only one toxicant. There was no significant interaction (P > 0.05) between the two toxicants, but an additive effect instead. Copper accumulation in Sydney Rock Oyster spat increased significantly (P < 0.05) 1.2-times in the presence of 20 ng TBTO l−1.
David A Raftos - One of the best experts on this subject based on the ideXlab platform.
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Progress on the Genome Characterisation of the Sydney Rock Oyster (Saccostrea glomerata)
2017Co-Authors: Daniel Powell, Wayne A. O'connor, David A Raftos, Abigail ElizurAbstract:The Sydney Rock Oyster (Saccostrea glomerata) is considered a delicacy in restaurants worldwide and is an economically important cultured marine species in Australia. For the last century, Oyster farming has been the most valuable aquaculture industry in the state of New South Wales, where the production of S. glomerata can reach over USD$26 million per year. Contending with disease and environmental stress are considerable challenges to Oyster culture and the manipulation of reproductive condition is vital for production and marketing. However, like many other shellfish, little is known of the molecular mechanisms underpinning these traits. The generation of a high quality draft genome can offer insights into these mechanisms, however, it also presents difficulties due to the high levels of heterozygosity and repetitiveness seen in Oysters. Here we present a draft S. glomerata genome using over 300X coverage of illumina small insert paired-end and mate-pair libraries with an additional Chicago library and HiRise scaffolding from Dovetail Genomics. The draft assembly has a total sequence length of 788 Mb, a scaffold number of 10,107 with an N50 of 804 Kb. Ongoing efforts include refining gene models using RNA-Seq data from a range of different tissues. The draft genome will serve as a platform to support genetic breeding programs and has already begun to facilitate further research investigating the influence of neuropeptides in the regulation of reproduction.
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a proteomic analysis of the effects of metal contamination on sydney Rock Oyster saccostrea glomerata haemolymph
Aquatic Toxicology, 2011Co-Authors: Emma L Thompson, Sham V Nair, G F Birch, Daisy A Taylor, Paul A Haynes, David A RaftosAbstract:The current study uses proteomics to assess the effects of metal contamination on Sydney Rock Oyster haemolymph. Saccostrea glomerata were exposed in aquaria for four days to three environmentally relevant metals (copper, lead or zinc). Oyster haemolymph proteins from metal-exposed Oysters were then compared to haemolymph from non-exposed controls using 2-dimensional electrophoresis to identify proteins that differed significantly in intensity. These proteins were then subjected to tandem mass spectrometry so that putative protein identities could be assigned. The data suggest that there are unique protein expression profiles for each metal. Exposure to 100 μg/l of copper, lead or zinc yielded a total of 25 differentially expressed proteins. However, only one of these protein spots exhibited altered intensities in response to all three metals. Eighteen of the 25 spots were significantly affected by just one of the three metals. Differentially expressed proteins were assigned to five different categories of biological function. Proteins affecting shell properties were the most common functional group accounting for 34% of the identified proteins. Cytoskeletal activities and metabolism/stress responses each accounted for a further 25% of the proteins.
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Disease prevention strategies for QX disease (Marteilia sydneyi) of Sydney Rock Oysters (Saccostrea glomerata)
Journal of Shellfish Research, 2011Co-Authors: Timothy J Green, Wayne A. O'connor, David A Raftos, Robert D. Adlard, Andrew C. BarnesAbstract:The Sydney Rock Oyster (Saccostrea glomerata) forms the basis of an important aquaculture industry on the east coast of Australia. During the 1970s, production of S. glomerata began to decline, in part as a result of mortalities arising from Queensland unknown (QX) disease. Histological studies implicated the paramyxean parasite Marteilia sydneyi in the disease outbreaks. Disease zoning was implemented to prevent the spread of M. sydneyi-infected Oysters. This control measure hindered Rock Oyster farming, which historically has relied on transferring wild-caught spat between estuaries for on-growing to market size and has not prevented the subsequent occurrence of QX disease in the Georges and Hawkesbury rivers in central New South Wales. Management of QX disease has been hampered by the complicated life cycle of M. sydneyi, with outbreaks of QX disease likely to be regulated by a combination of the abundance of intermediate host of M. sydneyi, environmental stressors, and the immunocompetence of S. glomerata. The future of the Sydney Rock Oyster industry relies on understanding these factors and progressing the industry from relying on farming wild-caught seed to the successful commercialization of hatchery-produced QX-resistant S. glomerata.
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The proteomic response of larvae of the Sydney Rock Oyster, Saccostrea glomerata to elevated pCO2
The Australian zoologist, 2011Co-Authors: Laura M. Parker, Pauline M. Ross, David A Raftos, E. T Thompson, Wayne A. O'connorAbstract:The acidification of oceans is predicted to fundamentally alter marine ecosystems. Previous studies have found that elevated CO2 has an effect on adult calcification, fertilisation and larval development, perhaps because of the organisms' inability to regulate acid-base status, but little is known about the mechanisms that underlie such responses. This study investigated the growth response of larvae of a wild and selectively bred line of the Sydney Rock Oyster, Saccostrea glomerata, to elevated CO2 and measured the pattern of expression of proteins. Overall exposure to elevated CO2 caused a significant reduction in the shell length of D-veliger larvae of the wild, but not in the selectively bred line. Prior to this study, differences in growth between selectively bred and wild Oysters have only been found following settlement. Proteome analysis of D-veliger larvae using two-dimensional gel electrophoresis detected a significantly greater number of protein spots in selectively bred compared to wild Oyster...
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phagocytosis of the protozoan parasite marteilia sydneyi by sydney Rock Oyster saccostrea glomerata hemocytes
Journal of Invertebrate Pathology, 2010Co-Authors: Rhiannon P. Kuchel, Debra Birch, Saleem Aladaileh, Nicole G F Vella, David A RaftosAbstract:QX disease is a fatal disease in Sydney Rock Oysters caused by the protozoan parasite Marteilia sydneyi. The current study investigates the phagocytosis of M. sydneyi by Sydney Rock Oyster hemocytes. It also compares the in vitro phagocytic activities of hemocytes from Oysters bred for QX disease resistance (QXR) with those of wild-type Oysters. After ingestion of M. sydneyi, hemocyte granules fused with phagosome membranes and the pH of phagosomes decreased. Significantly (p = <0.05) more phagosomes in QXR hemocytes showed obvious changes in pH within 40 min of phagocytosis, when compared with wild-type hemocytes. Phenoloxidase deposition was also evident in phagosomes after in vitro phagocytosis. Most importantly, ingested and melanised M. sydneyi were detected in vivo among hemocytes from infected Oysters. Overall, the data suggest that Sydney Rock Oyster hemocytes can recognise and phagocytose M. sydneyi, and that resistance against QX disease may be associated with enhanced phagolysosomal activity in QXR Oysters.
Rosalind E. Hand - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the progeny of second generation sydney Rock Oyster saccostrea glomerata gould 1850 breeding lines for resistance to qx disease marteilia sydneyi
Aquaculture, 2003Co-Authors: John A. Nell, Rosalind E. HandAbstract:Abstract The progeny of second-generation Sydney Rock Oyster Saccostrea glomerata (Gould, 1850) breeding lines were tested for resistance to QX disease Marteilia sydneyi against a non-selected control. Mortality was reduced from 85.7±1.5% for the controls to 63.5±1.2% for the most improved breeding line. This is a reduction in mortality of 22% after only two generations of selection. These partially QX disease-resistant Oysters in which M. sydneyi was found were also 21% heavier than controls. Selection for resistance to M. sydneyi is feasible and may be improved through further selection.
Michael Dove - One of the best experts on this subject based on the ideXlab platform.
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dynamics of the sydney Rock Oyster microbiota before and during a qx disease event
Aquaculture, 2021Co-Authors: Viet Khue Nguyen, Wayne A Oconnor, Michael Dove, William L King, Nachshon Siboni, Khandaker Rayhan Mahbub, Justin R Seymour, Hafizur Rahman, Cheryl Jenkins, Maurizio LabbateAbstract:Abstract The Sydney Rock Oyster (SRO; Saccostrea glomerata) is the most intensively farmed Oyster species in Australia however, Queensland unknown (QX) disease has resulted in substantial losses and impeded productivity. QX disease is caused by infection with the parasite Marteilia sydneyi, and like other diseases, outbreaks are driven by a series of complex environmental and host factors such as seasonality, seawater salinity and Oyster genetics. A potential but understudied factor in QX disease is the SRO microbiota, which we sought to examine before and during a QX disease outbreak. Using 16S rRNA (V1 – V3 region) amplicon sequencing, we examined the microbiota of SROs deployed in an estuary where QX disease occurs, with sampling conducted fortnightly over 22 weeks. Marteilia sydneyi was detected in the SROs by PCR (QX-positive), 16 weeks after the first sampling event and sporonts were observed in the digestive gland two weeks later on. There were no apparent patterns observed between the microbiota of QX-positive SROs with and without digestive gland sporonts however, the microbiota of QX-positive SROs was significantly different from those sampled prior to detection of M. sydneyi and from those negative for M. sydneyi post detection. As a result, shifts in microbiota structure occurred before sporulation in the digestive gland and either before or shortly after pathogen colonisation. The microbiota shifts associated with QX-positive Oysters were principally driven by a relative abundance increase of operational taxonomic units (OTUs) assigned to unclassified species of the Borrelia and Candidatus Hepatoplasma genera and a relative abundance decrease in an OTU assigned to an unclassified species of the Mycoplasma genus. Since Mycoplasma species are common microbiota features of SROs and other Oysters, we propose that there may be an important ecological link between Mycoplasma species and the health state of SROs.
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the sydney Rock Oyster microbiota is influenced by location season and genetics
Aquaculture, 2020Co-Authors: Viet Khue Nguyen, Wayne A Oconnor, Michael Dove, William L King, Nachshon Siboni, Khandaker Rayhan Mahbub, Justin R Seymour, Maurizio LabbateAbstract:Abstract Queensland unknown (QX) disease is a significant cause of economic loss for the Sydney Rock Oyster (SRO) aquaculture industry. Evidence is emerging that QX disease is multi-factorial in nature, with a number of environmental and host factors contributing to disease dynamics. Efforts to mitigate the impacts of QX disease are primarily focused on breeding for disease resistance however, the mechanisms that drive disease resistance are poorly understood. One potential factor influencing disease resistance is the microbiota. To determine the influence of location, season and disease resistance on the SRO microbiota, we used 16S rRNA (V1 – V3 region) amplicon sequencing. The microbiota of six SRO families with two categorised as QX-resistant and four as QX-susceptible, deployed to two different locations (Port Stephens and Wallis Lake, NSW, Australia) and over two seasons (Austral summer and winter), were characterised. As expected, the SRO microbiota was distinct to the microbial community found in seawater. Further, the SRO microbiota was significantly influenced by location and season, with operational taxonomic units (OTUs) assigned to the Candidatus Hepatoplasma and Endozoicomonas genera identified as significant drivers of microbiota dissimilarity between locations and seasons. Disease resistance also significantly influenced the SRO microbiota but only at the winter time point which is before the typical QX disease period. Overall, OTUs assigned to the Mycoplasma, Borrelia and Endozoicomonas genera were over-represented in QX-resistant SRO microbiota, whereas members of the Pseudoalteromonas, Vibrio, and Candidatus Hepatoplasma genera were over-represented in QX-sensitive microbiota. These findings confirm the influencing role of location and season on the microbiota structure as evidenced in other molluscan species, but also provide preliminary evidence that the microbiota assemblage before the QX disease period may be important for resistance to disease and may provide new avenues for managing SRO aquaculture in the future.
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can genetic diversity be maintained across multiple mass selection lines of sydney Rock Oyster saccostrea glomerata despite loss within each
Aquaculture, 2016Co-Authors: Wayne A Oconnor, Michael Dove, Wayne KnibbAbstract:This study assesses the genetic diversity of four different hatchery bred lines of Sydney Rock Oyster, Saccosstrea glomerata (SRO) after three, five and seven generations of mass selection using microsatellite DNA markers and mitochondrial cytochrome C oxidase subunit 1 sequences (COX1). This was achieved using seven newly developed microsatellite markers, along with three published loci. Considering the same number of samples in each line, the number of different alleles in each of the four hatchery lines ranged from 49 to 70 alleles from 10 loci, which was approximate 50% less than the 120 alleles found in the samples from the wild population. However, if we pool all our four hatchery lines together, then their total number of alleles was not significantly different from the wild population. Similar to the patterns found for the DNA microsatellite alleles, mtDNA haplotype numbers were considerably lower in each of the hatchery lines than in the samples from the wild population. Again, pooling the hatchery lines gave a total haplotype number not statistically significantly different from that in the samples from the wild. Considering together the DNA microsatellite alleles and the mtDNA haplotypes, we conclude that there was a substantial loss of genetic diversity within all lines separately over generations of mass selection, and that such mass selection was not sustainable in the long term. However, importantly, these data indicate that for Oysters, if multiple independent mass selection lines are kept, then their combined genetic diversity may approach that of the ancestral line or wild population even after many generations of mass selection. These results for Oysters, finding preservation of diversity among lines yet loss within them, are similar to recent findings for multiple banana shrimp lines; considering both species together it suggests that one relatively simple option suitable for some farms and industry to maintain genetic diversity during mass selection over many generations of selection is to subdivide their breeding nucleus and keep multiple different and independent lines over generations. It remains to be tested if this approach is general across many aquaculture species and circumstances.
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evaluation of the progeny of the fourth generation sydney Rock Oyster saccostrea glomerata gould 1850 breeding lines for resistance to qx disease marteilia sydneyi and winter mortality bonamia roughleyi
Aquaculture Research, 2006Co-Authors: Michael Dove, John A. Nell, Wayne A OconnorAbstract:A breeding program for Sydney Rock Oysters Saccostrea glomerata (Gould, 1850) has been selecting Oysters for resistance to QX disease (Marteilia sydneyi) and winter mortality (Bonamia roughleyi) for three generations at three sites in Georges River, New South Wales, Australia. The experimental sites are located at the upper, middle and lower reaches of Oyster growing areas in the estuary. QX disease mainly occurs in the middle and upper reaches and is most severe at the latter. Winter mortality on the other hand occurs mainly at the lower and middle reaches and is most severe at the former. Progeny of third-generation Sydney Rock Oyster breeding lines were evaluated for resistance to both QX disease and winter mortality against a non-selected control. Line 1, selected for QX disease resistance at the upper estuary site, had excellent resistance to one season of exposure to disease, but suffered high mortality during the second season of exposure. However, these Oysters had already reached market size of 50 g whole weight, with low mortality at 2 years of age, before the second episode of QX disease. Line 2 showed good improvement in resistance to both diseases, whereas Line 3, was the most resistant to winter mortality. Selection for resistance to QX disease did not appear to confer resistance to winter mortality and the converse also applied.
