Analysis of hsp 30, hsp 70 and ubiquitin gene expression in Xenopus laevis tadpoles.

Heat-induced accumulation of hsp 30 mRNA (1.1 kb) during early development of Xenopus laevis was first detectable at the tailbud stage (stage 30-34). This contrasts with heat-induced accumulation of hsp 70 mRNA (2.7 kb) and ubiquitin mRNA (size range = 1.7-3.1 kb), which was first detectable at the mid- to late-blastula stage. Continuous exposure of tadpoles to a 33 degrees C heat shock resulted in a coordinate, transient accumulation of hsp 30, hsp 70 and ubiquitin mRNA. A coordinate, temporal pattern was also observed for the decay of hsp 30, hsp 70 and ubiquitin mRNA in tadpoles recovering at 22 degrees C following a 1 h heat shock at 33 degrees C. Thus, while hsp 30 genes are regulated differently during development compared with hsp 70 and ubiquitin genes, these genes all exhibit a coordinate heat-inducible pattern of expression at the tadpole stage. Levels of alpha-cardiac actin mRNA remained unchanged during continuous heat shock and recovery experiments.