[The regression time of heat-shock puffs in the polytene chromosomes of Drosophila melanogaster as a criterion for assessing the effect of different stress exposures].

The time of regression of heat shock puffs was studied in the polytene chromosomes of Drosophila melanogaster larvae of mutant stock (1(1)ts403, defective in heat shock protein (HSP) system, and of the wild type stock Canton S after heat shock (37 degrees C), after placing of larvae to anaerobic conditions (dipping into physiological solution), and after combination of these treatments. It is shown that the time of regression of heat shock puffs depends on the specificity of the treatment (heat shock or anaerobic conditions), its duration (13 or 30 min), or on the peculiarity of functioning of HSP system in the cells of different stock larvae. Our results are in accordance with the idea of the HSP genes expression autoregulation, and allow to use the heat shock puff regression time as a criterion for estimation of damaging effects of stress factors.