New data on the hereditary adaptive increase in thermostability in the forked mutant of Drosophila melanogaster under repeated thermal shock.

It was confirmed that forked mutants of D. melanogaster strain C(I)RM developing after a single intrauterine heating of oocytes in females at 39 degrees for 30 and 45 min exhibited changes in the average number of anomalous thoracic macrochaetae on females: heating for 30 min caused a decrease (normalization of the phenotype), while heating for 45 min caused an increase (intensification of mutation expression). It was established that these changes are inherited maternally, in the same manner as long-term Jollos modifications. Evaluation of the number of anomalous thoracic macrochaetae in parallel strains of flies after heating of the oocytes during the critical periods of macrochaeta development (seven days before egg laying), i.e., the stage of oocyte formation in the germarium. Heating of oocytes in F2t1 females "preliminarily heated in the F1 generation showed that the stability curve for the oocytes after "preliminary" heating during the critical developmental period exhibited an abrupt decrease rather than the anticipated rise, which can only be attributed to an adaptive increase in oocyte thermostability as a result of preliminary heating.