The Threshold Induction Temperature of the 90-kDa Heat Shock Protein is Subject to Acclimatization in Eurythermal Goby Fishes (Genus Gillichthys)

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 89; no. 8; pp. 3389 - 3393
• Main Authors: Dietz, Thomas J., Somero, George N.
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 15.04.1992; National Acad Sciences; National Academy of Sciences
• Subjects: Acclimatization; Animals; Biological and medical sciences; Blotting, Western; Brain - physiology; Fish; Fishes - physiology; Freshwater; Fundamental and applied biological sciences. Psychology; Gels; Gillichthys mirabilis; Gillichthys seta; Heat shock proteins; Heat shock response; Heat-Shock Proteins - biosynthesis; Heat-Shock Proteins - isolation & purification; HSP90 protein; Molecular Weight; Proteins; Radioactive decay; seasonal variations; Seasons; Shock heating; Species Specificity; Temperature; Temperature control; Thermoregulation. Hibernation. Estivation. Ecophysiology and environmental effects; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Water temperature; Winter; Brackish water environment; Vertebrata; Temperature; Induction; Pisces; Heat shock protein; Environmental factor; Biosynthesis; Adaptation; Quantitative analysis; Brain (vertebrata)
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.89.8.3389

Two extremely eurythermal goby fishes, Gillichthys mirabilis and Gillichthys seta, which encounter habitat temperature variations of ≈30⚬C, showed seasonal acclimatization of endogenous levels and of onset temperatures for enhanced synthesis of a 90-kDa-class heat shock protein (HSP90). Summer-acclimatized fishes had higher levels of HSP90 in brain tissue than winter-acclimatized specimens, as shown by Western blot analysis. For winter-acclimatized fishes, increased synthesis of HSP90 was observed when the temperature was raised from a control temperature (18⚬C) to 28⚬C. For summer-acclimatized fish, no significantly increased synthesis of HSP90 occurred until the experimental temperature was raised to 32⚬C. These data suggest that the threshold temperature at which enhanced expression of HSP-encoding genes occurs is not hard-wired genetically but may be subject to acclimatization. A causal relationship between seasonal changes in steady-state levels of HSP90 and the threshold temperature for enhanced HSP90 synthesis is discussed in terms of existing models for the regulation of HSP gene expression.