In situ hybridization with polytene chromosomes was used to demonstrate the transposition of mobile dispersed genes (mdg)-1 and 3 following the selection of flies from low reproductive activity and viability (LA stock) for high reproductive activity, viability and fitness (LA+ and HA stocks). The inbred LA stock is continuously selected for low reproductive activity and viability and maintains at least for twenty-five generations a characteristic pattern of mdg-1 distribution in 14-15 sites. Inbred LA+ and HA stocks exhibit a changed pattern of mdg-1 locations and the number of sites reaches 21-25. Parallel and independent selection for higher viability may lead to similar characteristic changes in the localization of mdg-1. In several independent experiments we observed, within one generation, a spontaneous and saltatory growth of viability and fitness in the mass-bred LA stock. In these cases new mdg-1 and mdg-3 sites reproducibly appeared to within several bands, some of them characteristic of LA+ and HA stocks. We discuss the possible role of mdg in determining the quantitative characters of individuals and their fitness.

Salivary gland polytene chromosomes demonstrate banding pattern, genetic meaning of which is an enigma for decades. Till now it is not known how to mark the band/interband borders on physical map of DNA and structures of polytene chromosomes are not characterized in molecular and genetic terms. It is not known either similar banding pattern exists in chromosomes of regular diploid mitotically dividing nonpolytene cells. Using the newly developed approach permitting to identify the interband material and localization data of interband-specific proteins from modENCODE and other genomewide projects, we identify physical limits of bands and interbands in small cytological region 9F13-10B3 of the X chromosome in D. melanogaster, as well as characterize their general molecular features. Our results suggests that the polytene and interphase cell line chromosomes have practically the same patterns of bands and interbands reflecting, probably, the basic principle of interphase chromosome organization. Two types of bands have been described in chromosomes, early and late-replicating, which differ in many aspects of their protein and genetic content. As appeared, origin recognition complexes are located almost totally in the interbands of chromosomes.

SummaryThe radius incompletus mutation (ri) causes a gap in the radial wing vein, L2. A control line (riC) of the mutation ri was selected for increase and decrease of radial vein. In the riSN strain, extreme expression of this quantitative character is almost complete elimination of L2 (negative selection : SN). In the riSP strain, the L2 vein is almost restored (positive selection : SP

A cluster of genes corresponding to the early ecdysone stimulated puff 2B of the Drosophila melanogaster X chromosome has been localized using in situ hybridization in eight Drosophila species. Genes ecs, dor and swi from this cluster have been mapped in D. funebris, D. virilis, D. hydei, D. repleta, D. mercatorum and D. paranaensis to the telomeric region of the X chromosome, in D. kanekoi to the distal region, and in D. pseudoobscura, to the proximal region of the X chromosome. It is assumed that organization of this cluster in these species is conserved. In D. hydei, multiple hybridization sites of certain DNA probes from this region were found.