[Ecdysone-dependent changes in the activity of ontogenetic puffs in the salivary glands of Drosophila cultivated in vitro as regards the effect of heterosis and selection of adaptively significant characters]. / Ekdizonzavisimye izmeneniia aktivnosti pufov ontogeneza v sliunnykh zhelezakh Drozofily, kul'tiviruemykh in vitro, v sviazi s éffektom geterozisa i otborom po adaptivno vazhnym priznakam.

Regression of 4 intermolt and induction of 14 early ecdysone puffs in two inbred stocks of Drosophila with high (HA) and low (LA) activity and hybrid F1 HA x LA were studied. Experiments were performed in vitro with ecdysone-containing media. Differences in developmental rate and fitness of stocks HA, LA and their hybrid were shown to correlate with the rate of change in polythene chromosomes puffing activity. Adaptive heterosis and ontogenetic homeostasis mechanisms are under discussion in connection with the results obtained.

[Parallel changes in the puffing of polytene chromosomes and bioelectric properties of salivary gland cell nuclei in Drosophila melanogaster after heat shock]. / Parallel'nye izmeneniia pufinga politennykh khromosom i bioélektricheskikh svoistv kletochnykh iader v sliunnykh zhelezakh Drosophila melanogaster posle teplovogo shoka.

The dynamics of heat-shock puff activity and cell nuclei electrophoretic mobility in the larvae salivary glands of normal and temperature-sensitive mutant stocks of Drosophila melanogaster after heat shock (37 degrees C) were studied. The parallel changes of these characters and interlinear differences affected by ts mutation were found. Positive correlation between heat shock puff size and cell nuclei electrophoretic mobility was detected.

[Dynamics of heat shock puffs in highly-inbred strains and heterosis hybrids of Drosophila melanogaster]. / Osobennosti dinamiki pufov teplovogo shoka u vysokoinbrednykh linii i geterozisnykh gibridov Drosophila melanogaster.

This study is aimed at elucidating the mechanisms of high heat resistance of heterosis hybrids. For this purpose, the dynamics of heat shock puffs of the high-inbred HA and BA lines as well as the HAxBA heterosis hybrids has been studied. Inadaptive properties of the HA line were observed to be expressed at the organism and cell levels, which is reflected by later induction of heat shock puffs. In the hybrids, these puffs occur considerably quicker, when heated, than with the high-inbred lines. Our conclusion is that the dynamics peculiarities of heat shock puffs reflect the differences in line and hybrid heat resistance. The higher heat resistance of the hybrid manifests itself in an earlier induction of heat shock puffs.