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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC CHARACTERIZATION AND IMPROVEMENT OF SHELLFISH BREEDING STOCKS FOR THE PACIFIC NORTHWEST Title: Use of laboratory assays to predict subsequent growth and survival of Pacific oyster (Crassostrea gigas) families planted in coastal waters

Authors
item Lang, R -
item Langdon, Christopher -
item Taris, Nicolas
item Camara, Mark

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 25, 2010
Publication Date: May 5, 2010
Citation: Lang, R.P., Langdon, C.J., Taris, N.G., Camara, M.D. 2010. Use of laboratory assays to predict subsequent growth and survival of Pacific oyster (Crassostrea gigas) families planted in coastal waters. Aquaculture. 306:68-79.

Interpretive Summary: Selective breeding programs for improving Pacific oyster (Crassostrea gigas) stocks are expensive, labor-intensive, and rely on lengthy field trials that are subject to stochastic outbreaks of Summer Mortality Syndrome. Laboratory assays that identify and eliminate poor-performing families prior to planting could improve selection efficiency. We examined whether it is possible to predict the growth and survival of oyster families in the field based on tests performed on juveniles before plant-out into subtidal and intertidal growout areas. We tried both family-specific mortality after laboratory heat shock assay and measurements of gene expression (messenger RNA or mRNA) for 14 candidate genes identified by previous research both before and after a non-lethal heat shock. We found no significant family-level correlations between juvenile survival after heat shock and subsequent survival, yield, or average individual weight at the subtidal site or the intertidal site. The mRNA concentration of galectin was greater in low-surviving families before heat shock, whereas cystatin B expression was higher in high-surviving families before and after heat chock and expression of glutathione S-transferase omega greater in high-surviving families only after heat shock. The pre-stress differences in expresseion suggest that survival of stress may be related to being prepared before stress rather than responding after stress occurs. The concentrations of heat shock protein 27, catalase, prostaglandin E receptor, and superoxide dismutase mRNA were significantly correlated with survival and average weight at the intertidal or subtidal sites. Additionally, the concentrations of galectin and an unidentified mRNA BQ426658 were correlated with average weight at either the intertidal or subtidal site, and concentrations of tissue inhibitor of metalloprotease mRNA were correlated with yield at both sites. We conclude that assays measuring gene transcription in whole bodies of juveniles hold promise for predicting performance of C. gigas families planted in coastal waters.

Technical Abstract: Selective breeding programs for improving Pacific oyster (Crassostrea gigas) stocks are expensive, labor-intensive, and rely on lengthy field trials that are subject to stochastic outbreaks of Summer Mortality Syndrome. Laboratory assays that identify and eliminate poor-performing families prior to planting could improve selection efficiency. We tested the hypotheses that survival after heat shock or gene transcription before or after heat shock in juveniles is predictive of the field performance of adult hatchery-produced full-sib families of the Pacific oyster. We heat-shocked (41°C for 1h) juveniles from each of 46 families, monitored their survival for 6 d and classified families with > 69% survival as high-surviving and those with < 31% survival as low-surviving. We deployed unstressed siblings from all 46 families at one subtidal and one intertidal site in Yaquina Bay, Newport, OR. In a separate experiment, we heat-shocked (39 °C, 1 h) another 25 juveniles from four low-surviving and four high-surviving families from the same cohort, extracted mRNA from whole bodies collected before and at 6 h and 24 h after heat shock, and measured the mRNA concentrations of 14 genes relative to a housekeeping gene (elongation factor 1) using real-time quantitative PCR. Oysters from the 46 families deployed were harvested after two years, and we estimated family-specific average survival (%), average individual weight (g), and yield (kg per bag). There were no significant family-level correlations between juvenile survival after heat shock and subsequent survival, yield, or average individual weight at the subtidal site or the intertidal site (P > 0.05). The mRNA concentration of galectin was greater in low-surviving families before heat shock, whereas those of cystatin B at all sampling times and of glutathione S-transferase omega at 24 h after heat shock were greater in high-surviving families. The pre-stress differences in transcription between the family types suggest that survival of stress may be related to constitutive differences in transcription between family types in addition to induced responses to heat shock. The concentrations of heat shock protein 27, catalase, prostaglandin E receptor, and superoxide dismutase mRNA were significantly correlated with survival and average weight at the intertidal or subtidal sites. Additionally, the concentrations of galectin and an unidentified mRNA BQ426658 were correlated with average weight at either the intertidal or subtidal site, and concentrations of tissue inhibitor of metalloprotease mRNA were correlated with yield at both sites. We conclude that assays measuring gene transcription in whole bodies of juveniles hold promise for predicting performance of C. gigas families planted in coastal waters.

Last Modified: 10/31/2014
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