Genetics of esterases in Drosophila. V. Characteristics of the "pupal" esterase in D. virilis

Genetics of esterases in Drosophila. IX. Characterization of the JH-esterase in D. virilis

The kinetic characteristics of the main isozymes of Drosophila virilis esterase were studied and Km values of esterase-2, -4, and -6 and p-esterase for alpha- and beta-naphthyl acetate were obtained. Juvenile hormone (JH) was shown to inhibit the p-esterase activity when in competition with beta-naphthyl acetate and the general esterase inhibitor, diisopropylphosphofluoridate (DFP), was shown to inhibit all the components of the D. virilis esterase patterns except p-esterase. While studying the changes of p-esterase activity in D. virilis ontogenesis, the increase in p-esterase activity in the wandering larvae, prepupae, and early pupae was found to correlate with a decrease in JH titer at these stages. The decrease in JH level in a temperature-sensitive lethal mutant larvae of D. virilis at high temperatures was shown to correlate with increased p-esterase activity. These results confirm that p-esterase of D. virilis is JH-esterase.

The genetics of esterases in Drosophila. VIII. The gene regulating the activity of JH-esterase in D. virilis

The content of JH-esterase was assayed by radial immunodiffusion in Drosophila virilis pupae under normal conditions and under the effects of extreme factors. It was found that JH-esterase content is the same (not different from the control) in pupae showing a high activity of the enzyme and in those not showing it. These data are evidence for a gene controlling JH-esterase activity. It was also shown that a regulatory factor converts inactive into active JH-esterase when homogenates of pupae, with active and inactive forms, were mixed and incubated together. It was demonstrated that the source of the activating factor is the larval brain. Sublines 147-R and 147-I were produced by introducing the second chromosome pair of stocks 103 and 101, which are heat resistant, into the genome of individuals of stock 147, which is heat sensitive. Sublines 160-III, 160-IV, 160-V, and 160-VI were produced by introducing the third, fourth, fifth, and sixth chromosome pairs of stock 147 into the genome of stock 160S, which is heat-resistant. The results of analysis of JH-esterase activity and the viability of individuals of these sublines at high temperatures indicated that the gene regulating the activity of JH-esterase is located in the sixth chromosome of D. virilis.

Genetics of esterases in Drosophila. VII. Genetic control of the activity level of juvenile hormone (JH)-esterase and heat resistance in D. virilis at high temperatures

The heat-resistant subline 147S was obtained in Drosophila virilis by selecting for viability individuals of heat-sensitive stock 147. It was shown that in the heat-treated 147S pupae the activity of juvenile hormone (JH)-esterase is decreased and, consequently, the titer of juvenile hormone is increased compared with those in the control pupae. These changes are consistent with those observed earlier for resistant stock 101. Heat-resistant stocks 101 and 147S were crossed with heat-sensitive stock 147, whose heat-treated larvae show earlier activation and higher activity of JH-esterase than control larvae. The viability and electrophoretic esterase patterns were analyzed in the F1 and F2 hybrids at different temperatures. It was found that the F1 hybrid is resistant to the effect of high temperature and its activity level of JH-esterase is lower compared with controls. In the F2 hybrid, there was a 3:1 segregation of viability and a 1:2:1 segregation of the activity level of JH-esterase at high temperatures. It is concluded that the activity level of JH-esterase and heat resistance in D. virilis are monogenically controlled at high temperatures.