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Abstract
The life span alteration after γ-irradiation and/or paraquat treatment in Drosophila in wild type strain Canton-S and strains with mutations of heat shock factor (1-4 alleles) and heat shock proteins (Hsp70Ba 304 , Hsp83 e6A , Hsp22 EY09909 , Hsp67Bb EY099099 ) was investigated. Chronic low-dose rate γ-irradiation (0.017 and 0.17 cGy/h) on pre-imago stages was used as a priming dose (absorbed doses were 4 and 40 cGy). Paraquat, a free radical inducing agent, was a challenging factor (20 mM for 1 day). It was shown that chronic irradiation led to adaptive response in both sexes except homozygous males and females with mutations of Hsf 4 and Hsp70Ba 304 . The gender-specific differences in stress response were discovered in wild type strain Canton-S, Hsp22 EY09909 Hsp67Bb EY09909 homozygotes and Hsp83 e6A heterozygotes: the adaptive response persisted in males, but not in females. Thus, Drosophila Hsp and Hsf mutation homozygotes did not demonstrate the adaptive response in the majority of cases, implying an important role of those genes in radiation hormesis and adaptation to stresses.