SALINITY STRESS PROTEINS IN EURYTEMORA-AFFINIS

Seasonal densities of Eurytemora affinis, a calanoid copepod in the Ch esapeake Bay, seem to be controlled by temperature and salinity. To ex amine the role of osmotic stress we analyzed protein synthesis under v arious conditions of temperature and osmotic stress. Adult females wer e exposed in groups for 5 hours to different temperature and salinity regimes in the presence of isotope-labelled amino acid. Newly synthesi zed (stress) proteins could be separated and identified using polyacry lamide gel electrophoresis and autoradiography. The protein profiles o ccurring in copepods experiencing osmotic shock alone were different f rom those of control animals. Copepods transferred to lower (2 and 5 p arts per thousand) and higher (15 and 20 parts per thousand) salinitie s showed differences in the up- and down-regulation of specific protei ns. Concurrent heat stress changed these protein patterns. Animals exp eriencing osmotic and heat shock at the same time exhibited enhanced e xpression of another set of proteins. Variation in induced proteins oc curred among individuals.