Meeting Abstract
P1.43 Saturday, Jan. 4 15:30 The effects of fluctuating salinity on protein profiles in echinoderm larvae of Dendraster excentricus and Pisaster ochraceus BASHEVKIN, S*; WESSEL, G; GEORGE, S.B.; Tufts University, Medford, Massachusetts; Brown University, Providence, Rhode Island; Georgia Southern University, Statesboro, Georgia georges@georgiasouthern.edu
Salinity fluctuations are common in the Salish Sea of the Pacific Northwest and are expected to become more common as global warming continues to increase the rate of glacial melting. Increased freshwater into the Salish Sea via rivers can cause the salinity to drop to 20 ppt from the normal level of 30. This occurs during the summer months when many marine invertebrates are reproducing. Echinoderms are especially affected since they cannot osmo- or ion- regulate. In this study we investigated the effects of fluctuating salinity on protein expression in larvae of 2 ecologically important echinoderms: the sand dollar Dendraster excentricus and the seastar Pisaster ochraceus. Larvae were reared in 2 treatments: control (constant salinity of 29-30 ppt) and fluctuating salinity (salinity dropped to 21 ppt for 2 days every ~7 days). Larvae were sampled periodically, analyzed for protein content by the Bradford Assay, and proteins separated by SDS-PAGE. Pisaster larvae exposed to fluctuating salinity expressed more large molecular weight proteins (301-310 and 240 kDa) than those in the controls. Dendraster larvae exposed to fluctuating salinity expressed more small molecular weight proteins (48, 74, 34, and 15 kDa) while those in the controls expressed more of a 97 kDa protein. Several proteins remained unchanged regardless of treatment, including 180, 98, and 81-82 kDa proteins in P. ochraceus and a 46-47 kDa protein in D. excentricus larvae. This is the first study to report the effects of low salinity on protein expression in echinoderm larvae. Future studies will identify these proteins and determine whether they function in metabolism, skeletogenesis, ion-transport or muscle development.
