Meeting Abstract

46.5  Monday, Jan. 5  Proteomic response of the Pacific oyster, Crassostrea gigas, to nitrate and salinity fluctuations HITT, Lauren R*; TOMANEK, Lars; California Polytechnic State University, San Luis Obispo lhitt@calpoly.edu

Pacific oysters, Crassostrea gigas, are commonly grown in California estuaries where they experience great fluctuations in nitrate and salinity. Nitrate enters the marine environment through freshwater run-off during heavy winter rains, often from agricultural areas and sewage effluent, and therefore it is important to study the response of oysters to hyposaline conditions. To investigate the global changes in protein expression that accompany nitrate and salinity stress in C. gigas, we applied a proteomics approach using two-dimensional gel electrophoresis and mass spectrometry. Gill tissues were exposed to a range of nitrate levels (0 mg/L, 5 mg/L, 25mg/L, 50mg/L and 100mg/L NaNO3) for six hours. Subsequently tissues were homogenized to prepare proteins for separation according to their isoelectric point (pI) and molecular mass using two-dimensional gel electrophoresis. The analysis yielded twenty-two proteins that changed expression when compared to the control (p-value< 0.05). We also exposed gill tissues to changing levels of salinity (100%, 90%, 80% and 70% filtered seawater) for 6 hours and analyzed their protein expression. We found a total of eighteen proteins that were significantly (p-value< 0.05) different. The proteins of interest were excised and digested with trypsin. A matrix-assisted laser desorption ionization (MALDI) tandem time-of-flight mass spectrometer was used to produce peptide fingerprints for each protein. Preliminary results show that several stress proteins are up-regulated with nitrate exposure. Other proteins are currently being analyzed to establish their identity in order to describe the physiological response of oysters to nitrate and hyposaline conditions.