Ecologically relevant variation in induction and function of heat shock proteins in marine organisms

Ectothermic organisms often face dramatic traverses of environmental temper ature on a daily or seasonal basis; exemplars among this group are inverteb rates and fish of the rocky intertidal zone. Because of the extremes of tem perature exposure, intertidal animals have served as an excellent study sys tem to examine the expression of heat shock proteins (Hsps) in response to natural variation in environmental temperature. Ecologically relevant varia tion in Hsp expression has been observed with seasonal acclimatization, wit h small-scale temperature gradients that occur in microhabitats and between species with different intertidal distributions. The maturing understandin g of Hsp expression patterns in marine organisms has established a solid fo undation on which to build the nest set of questions. In this paper, I pres ent an overview of the variation of Hsp expression in intertidal animals in nature and then address two emerging areas of investigation in the ecologi cal physiology of Hsps. One area addresses the plasticity of Hsp expression in marine invertebrates and focuses on the mechanism of regulation of Hsp gene expression by environmental temperature. A second emerging area of inv estigation concerns whether Hsps as molecular chaperones display functional diversity that correlates with species' adaptation temperature.