[Esterase-6 gene-enzyme system and resistance of Drosophila to increased temperature].

The effect of the gene-enzyme system of esterase-6 (EST-6) on the expression of viability traits in Drosophila melanogaster was studied at normal and high temperatures. Interline, ontogenetic, and sexual differences of beta-esterase activity in tissue extracts were found. The differences were not correlated with the viability parameters of the flies.

[Expressivity of the gene-enzymatic system and viability indicators in the ontogenesis of Drosophila inbred lines and hybrids].

The activity, physico-chemical properties and multiple molecular forms of enzymes (alcohol dehydrogenase, superoxide dismutase, nonspecific alpha- and beta-esterases, hydroxide peptidohydrolase) were studied in ontogenesis of Drosophila inbred lines and their hybrids under conditions of high temperature (37-41 degrees C) and the presence in food of 10% ethanol. It was established that resistance of individuals to the effect of high temperature and alcohol, including manifestation of adaptive heterosis in hybrids not always depends on the level of the activity of enzymes analysed and is rather determined by allelic state of the appropriate structural genes. So, in conditions of the alcohol stress the individuals containing highly active F form of alcohol dehydrogenase have selective advantage and flie with hybrid F/S enzyme of higher activity and heat stability are more stable to the effect of high temperature.