Characterization of the heat shock response in mature zebrafish (Danio rerio)

Heat shock proteins (Hsps) are involved in many physiological and pathological processes and are diminished with age in a variety of species. As zebrafish embryos have proven to be excellent models for studying Hsp response during development, we sought to characterize the response in mature zebrafish to demonstrate the utility of the zebrafish model in studying late-life diseases and the biology of aging. Accordingly, mature zebrafish were exposed to a 37 degrees C heat stress and mRNA was isolated from various tissues and subjected to analysis by RT-PCR. We found that Hsp70 was upregulated in brain, liver, and muscle, while Hsp47 was upregulated in brain, but not liver or muscle. Hsp90alpha, Hsp90beta, and heat shock factor 1a (Hsf1a) were expressed in all three tissues, but were not upregulated in response to heat stress. A comparison of Hsp expression in young versus mature zebrafish revealed decreased basal levels of Hsp70 and increased levels of Hsf1a in mature fish. These results indicate that the heat shock response is detectable in mature zebrafish and that there are age differences in their heat shock response, suggesting that mature zebrafish may be a useful model for studying Hsp response during the aging process.