The
daf-21 (
p673) gene has been reported to encode the HSP90 homologue in C. elegans (Birnby DA et al., 2000). Not only does heat shock induce hsp genes, but also other environmental stresses have been found to do so. In the pathway of stress response to heat shock, two heat shock proteins, DAF-21 and HSP70, have been reported to restrain the activity of the heat shock transcription factor 1 (HSF1), which binds to heat shock elements and promotes hsp genes. The loss-of-function analysis for DAF-21 and HSP70 showed increased induction of hsp genes, thus indicating that DAF-21 and HSP70 function as negative regulators of HSF1. We previously reported that the mutation in
daf-21 resulted in a 1.5-fold overexpression of both
daf-21 and
hsp70 mRNA as shown by Northern blot analysis. Based on this observation, we now used RT-PCR analysis to quantify the mRNAs for both of these genes in N2 and Daf-21
(p673) and confirmed the previous results. As a new strategy, not only
hsp90 (
daf-21) but also other hsp genes, such as
hsp70,
hsp60, and
hsp16, were examined to establish a bioassay system by which we can detect and quantify chemical and physical stresses on C. elegans. We found that this group of hsp genes was induced in C. elegans exposed to chemicals such as Cadmium ion, alcohols, and aldehydes. We intend to develop this hsp assay system to be a general assay method to test, detect, and predict the toxicity of chemical compounds.