Genotypical Features in the Expression of Allozymes of β-Specific Hydrolase of Carboxylic Esters in Wild-Type Drosophila melanogaster

The expression level of electrophoretically separated S- and F-allozymes of beta-specific esterase (EC 3.1.1.2) in genotypes of wild-type Drosophila melanogaster (males and females) that are monozygous or heterozygous with respect to the locus beta-Est is determined by means of computerized densitometry; alpha-naphthylacetate, beta-naphthylacetate, and alpha-naphthylpropionate are used as the substrates. The intensity of the expression of the esterase is judged from the quantity of reaction product created as a result of simultaneous azo coupling between naphthol and diazonium in 4, 24, 44, and 64 min incubation times. Reliable differences in the expressions of the S- and F-allozymes as a function of the structure of the beta-Est locus of genotypically distinct individuals are established. In all the variant experiments, a higher level of summary activity of the S- and F-allozymes of the beta-esterase of the heterozygotes by comparison with the individual activity of the F-and S-allozymes of the corresponding homozygotes was demonstrated, independently of the sex of the Drosophila individual. A comparative estimate of the temporal dynamics of the expression of in vitro allozymes of the dominant homozygotes (beta-Est(S)/beta-Est(S)), heterozygotes (beta-Est(S)/beta-Est(F)), and recessive homozygotes (beta-Est(F)/beta-Est(F)) is performed. Possible mechanisms for the occurrence of heterosis according to the character of expression of S- and F-allozymes of beta-esterase on the basis of the theory of biochemical enrichment of heterozygote genotypes are considered.