BERGER, M.S.: Inducible heat-shock protein expression in two barnacle species, Balanus glandula and Balanus crenatus

In the intertidal, body temperatures of sessile marine organisms can reach 25-30 °C for extended periods of time during low tide. I examined the response to thermal stress in two barnacle congeners, Balanus glandula and Balanus crenatus, by measuring (1) the expression patterns of protein synthesis and (2) the difference in expression patterns between species. In addition, I measured the relative concentrations of ubiquitin conjugates to determine the extent of protein damage caused by thermal stress. Both species have different vertical distributions, with B. glandula distributed in the high intertidal and B. crenatus in the low intertidal/subtidal. Using metabolic labeling techniques, total protein synthesis in non-acclimated B. glandula suggested a trend for temperature induced protein expression to occur in the 90 and 50 kDa region, at 23 °C and 28 °C, with synthesis decreasing at 33 °C. Induction patterns were highly variable between individuals and therefore were not typical of published information on mussels and gastropods. In comparison, B. glandula acclimated at 12 °C for 5 weeks, displayed elevated protein synthesis in the 90 and 70 kDa region only at 33 °C. No significant increase in ubiquitin conjugates occurred as a function of thermal stress for non-acclimated or acclimated B. glandula, suggesting irreversible protein damage did not occur. Protein expression patterns in B. crenatus were similar to the non-acclimated B. glandula patterns. Relative ubiquitin conjugate levels for B. crenatus were significantly higher at 26 °C, compared to 12 °C and 23 °C, indicating that irreversible protein damage had occurred.