Abstract
Biochemical analysis of a number of related unstable Drosophila melanogaster strains was carried out. These strains have been shown to undergo mutational transformations caused by insertion/excision of transposable elements (Gerasimova, 1985). Activity and mobility variants of alpha-GPDH, ADH, SOD, G6PD, 6PGD and EST-6 were analysed. Two loci controlling SOD and 6PGD proved to be invariable, the loci alpha-Gpdh and Est-6 causing reduced activity of their products in the initial strain ctMR2. The direct and reversed transformations analogous to the mutational passages of morphological characters were traced in two loci controlling ADH and G6PD. The data obtained are discussed in terms of up-to-date views on the functional role of transposable elements, in relation to the genetic stability of the strains studied, under the multiple transpositions of mobile elements.