TOMANEK, Lars; Univ. of California, Davis: 2-DE comparison of the heat-shock protein complement in intertidal Tegula congeners.
Species of the genus Tegula occupy widely varying thermal habitats along the transition from the sub- to the intertidal zone and show distinct biogeographic distribution ranges. Separation of proteins using 1D gel-electrophoresis has shown that these congeners vary in their heat-shock response and its acclimatory plasticity. Transplant experiments have shown that this variation contributes to limiting the vertical height that a species can occupy in the intertidal zone. Here I present a high-resolution separation of the various heat-shock proteins of several molecular weight classes from three Tegula congeners following acclimation to 13�C and 23�C for three weeks. Using 35S-labelled amino acids, an exposure to 27�C induces the synthesis of six to nine low-molecular weight (LMW) isoforms of heat-shock protein 70 (Hsp70) of which up to four are strongly activated. There are an additional three clusters of high-molecular weight (HMW) Hsp70s with two to three isoforms. Hsp90 is represented with two isoforms. The number of small Hsps varies between one and three. For both, small Hsps and Hsp70, there is a greater number of isoforms in the mid-intertidal and heat-tolerant T. funebralis than in the subtidal and more heat-sensitive T. brunnea and T. montereyi. For T. funebralis I found few changes in the expression of Hsp isoforms with increasing acclimation temperature. In contrast, T. brunnea as well as T. montereyi changed the expression of several of their isoforms with acclimation to higher temperatures. This high-resolution comparison of Hsp synthesis patterns provides new insights into the evolutionary variation that separates snail species that occupy widely differing thermal environments.
