[Cytogenetic and cytobiophysical study of temperature adaptation and heterosis mechanisms in Drosophila melanogaster Meig].

The degree of polyteny of giant chromosomes and electrokinetic properties of cell nuclei salivary glands of Drosophila melanogaster were studied in relation to genotype and rearing temperature. Inbred and selected Drosophila lines and interlinear F1 hybrids were used. The experiments were conducted in three temperature regimes: 25 (control), 18, and 28 degrees C. At low (18 degrees C) and high (28 degrees C) temperatures, the degree of polyteny and number of electronegative nuclei was respectively higher and lower than in the control. The correlation of these parameters with a number of adaptive traits was studied. The results suggest that chromosome polyteny and nuclear electrokinetic potential play a significant role in heterosis and adaptation of Drosophila melanogaster to adverse temperatures.