ONTOGENY OF DROSOPHILA-MELANOGASTER IN A SYSTEM OF DYSGENIC CROSSES

Three families of mobile elements that induce P-M, H-E, and I-R hybrid dysgenesis in Drosophila melanogaster were activated by crossing flie s of different cytotypes. Manifestation of gonadal sterility in F-1 hy brid progeny was dependent on the temperature of development. The syst ems differed significantly in lethality of F-2 hybrids at various stag es of ontogeny (embryos, larvae, pupae, and adult flies). The highest embryo lethality was found in the P-M system at the cleavage stage. In the I-R and H-E systems, the peak of embryonic death corresponded to the stages of blastoderm and organogenesis, respectively. Experimental results are discussed in view of molecular and cytological characteri stics of interacting strains and existing hypotheses for regulation of transposition of P, hobo, and I mobile elements.