Heat Shock Responses of Closely Related Species of Tropical and Desert Fish

Abstract

*Department of Molecular and Cell Biology and ^Department of Ecology and Evolutionary Biology,University of Connecticut, Storrs, Connecticut 06269-3044SYNOPSIS. Ove the pasrt twelve years w, e have studied heat shock protein ins twotropical species a, half dozen desert specie ansd a number of hemiclones of vivip-arous fishes in the genus Poeciliopsis. Heat shock protei (Hsp isofor)n m patternswere determined using high resolution two-dimensional polyacrylamid Two e gels.families of Hsps were studied in detail, the nucleocytoplasmic 70 kilodalton Hsp70family and the 30 kUodalton Hsp30 family relate tdo a-crystallin. The temperaturedependence of Hsp accumulatio wan s investigated using both intact fish and cul-tured cells. Whe thn e threshold temperatures were mapped onto thermal prefer-ence profiles it, wa s apparent tha tht e Hsp70 threshold (33°C wa)s closely linkedto the most frequently selected temperature and thse Hsp30 threshold (37°C wa)sclosely linke tdo high temperatures that fish rarely selected, indicating that fishdeploy thes twe o molecular chaperones differently On.e tropical species P. gradlisis a genetic reservoir for most of the Hsp70 isoforms of the desert species. Acquiredresistance to 41°C was strongly correlated with Hsp70 abundanc for gracilie s thatcontained Hsp70 isofor 3m whereas fish lacking this isoform showed similar levelsof acquired thermotolerance whic did noht correlat e with Hsp70 abundance, sug-gesting multiple, compensating mechanism of acquires d resistance. Isofor 3m wasdegraded in cultured cells from a desert species during several hour of recovers yat normal temperature following heat shoc two othek wherear Hsp70s isoformswere stable Th. e implications of this propert oyf isoform 3 are discussed.