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Abstracts
Workgroup: Frontiers in Disease Research
An Investigation of the Stress Response Summer Mortality and Disease Resistance in Crassostrea gigas
Principal Investigator(s):
Carolyn S. Friedman and James S.Clegg, University of California at Davis, carolynf@u.washington.edu
Co-Investigator(s):
Gary N. Cherr, University of California at Davis
Funding Period: 1995-1998
This study characterized, for the first time, the stress response of the Pacific oyster, Crassostrea gigas. This species has the strongest stress response ever determined as evidenced by the production of stress or heat-shock proteins (hsp) and development of thermal tolerance (ITT) for up to 3 weeks.
- C. virginica has a shorter stress response (hsp production and ITT) than C. gigas.
- We developed a heat shock protocol and western blotting methods for the assessment of hsps in oysters.
- We demonstrated that using a sub-lethal heat shock on field-planted oysters shows promise to reduce mortalities in specific field situations.
- Oysters planted at high tidal heights (i.e. 3 ft above MLLW) experienced higher losses, failed to produce hsp 69.
- We characterized the hsp production of an oyster pathogen, Nocardia crassostreae, upon heat shock and determined that the hsp production lasted less than 1 hr. This information was used to test the stress response of Pacific oysters exposed to this bacterium.
- Using controlled laboratory studies, exposure to nocardiosis reduced survivorship. However, the oysters were still able to mount a stress response.
- We determined that exposure to hyposalinity delays the stress response: hsp production and ITT occur later than in ambient salinity cohorts. This response was independent of modulations in protein and moisture content.
- The cellular immune response of Pacific oysters was characterized under normal and stressed conditions (with nocardiosis and/or heat shock) and observed no significant effect in immune response upon exposure to nocardiosis or nocardiosis plus heat shock (p<0.05). However, we did observe significant alterations in immune cell function as a result of heat shock and reproductive maturation: immune capabilities were reduced.
IMPACTS and/or BENEFITS:
This research has had a tremendous impact on oyster culturists and researchers world-wide. Due to our studies, we understand the physiology of the oyster losses enough to better manage these losses. In addition, the tools we created are being used by researchers in many areas.
PROJECT PUBLICATIONS:
Friedman, C.S., Shamseldin, A., Olin, P.G., Robbins, T.T., and Cherr, G.N. In review. Investigation of a mass mortality of the Pacific oyster, Crassostrea gigas Thunberg, in Tomales Bay, California. Journal of Shellfish Research.
Hamdoun A M ; Cherr G. 2001. N. Phenotypic plasticity of HSP70 and HSP70 gene expression in the Pacific oyster (Crassostrea gigas): Implications for resting thermal limits and induction of thermal tolerance. American Zoologist. 41(6):1643-1644.
Hamdoun Amro M; Cheney Daniel; Elston Ralph; McDonald Brian; Cherr Gary N. 2000. Summer stress protein responses of cultured Pacific oysters: Does chronic stress
reduce tolerance? Journal of Shellfish Research. 19(1):599.
Friedman, C.S.,Cherr, G.N., Clegg, J.S., Hamdoun, A.H., Jacobsen, J.L., Jackson, S.A., and Uhlinger, K.R. 1999. Investigation of the stress response, summer mortality and disease resistance of oysters, Crassostrea spp. Journal of Shellfish Research 18(1):297.
Clegg, J.S., Uhlinger, K.R., Jackson, S.A., Cherr, G.N., Rifkin, E., and Friedman, C.S. 1998. Induced thermotolerance and the heat shock protein-70 family in the Pacific oyster, Crassostrea gigas. Molecular Marine Biology and Biotechnology 17(1):79-83.
Shamseldin Ally A; Clegg James S; Friedman Carolyn S; Cherr Gary N; Pillai Murali C. 1997. Induced thermotolerance in the Pacific oyster, Crassostrea gigas. Journal
of Shellfish Research. 16(2):487-491.
Friedman Carolyn S; Shamseldin Ally; Pillai Murali; Olin Paul G; Cherr Gary N; Jackson Susan A; Rifkin Erik; Uhlinger K R; Clegg James S. 1997. Summer mortality and the
stress response of the Pacific oyster, Crassostrea gigas Thunberg. Journal of Shellfish Research. 16(1): 335.
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