Alterations in the pattern of gene expression following heat shock in the nematode Caenorhabditis elegans

Exposure of the nematode Caenorhabditis elegans to elevated temperatures induces the preferential synthesis of eight major polypeptides of approximate molecular weights 81 000, 70 000, 41 000, 38 000, 29 000, 19 000, 18 000, and 16 000. In pulse-labelled worms these peptides first appear at 29 degrees C and continue to be synthesized up to lethal temperatures. They are heat inducible at every stage of development. While temperature elevation induces the synthesis of the heat-shock polypeptides, the in vivo synthesis of most other proteins present before heat shock is suppressed. In contrast, in vitro translation of mRNA from heat-shocked worms shows no alteration from the pattern of normal 20 degrees C mRNAs except for the appearance of the heat-shock mRNAs. An in vitro study of RNA from control and heat-shocked dauer larvae shows that this developmental variant possesses little translatable mRNA but, upon heat shock, synthesizes a set of messages corresponding to the heat-shock polypeptides. The low background of this system will be especially useful in the analysis and purification of heat-shock mRNA for molecular cloning experiments. Extensive similarities between the Drosophila and C. elegans heat-shock responses are shown, including homology between the 70-kdalton heat-shock genes of the two organisms.