Fine cytogenetical analysis of the band 10A1-2 and the adjoining regions in the Drosophila melanogaster X chromosome

Abstract

Focuses of the l(1)BP4, vermilion and sevenless genes located in the same band 10A1-2 of Drosophila melanogaster X-chromosome, have been compared. For this purpose first the fate map of the blastoderm for 60 pairs of adult cuticular landmarks has been built based on scoring 612 gynandromorphs. The location of the legs and antenna primordia has been defined more exactly as compared to analogous maps by other authors. The location of new landmarks has been carried out: mesosternal bristle, sex-comb and first tergite primordia. The focus of the l(1)BP4 gene has been determined with the help of this map on the basis of analysis of 321 mosaics. The data obtained show that the lethal focus of the gene belongs to the "bilateral domineering" type and is located in the blastula area giving rise to the nervous system, behind the region of the third thoracic ganglia origin. Beside, there is a pair of autonomous nonlethal focuses of the same gene limited by the wings' zone. The focuses of the l(1)BP4 gene do not coincide with the known focuses of vermilion and sevenless genes, which means that all three genes are active in different tissues.

Chromomeric organization of polytene chromosomes

“…ii) In the experiments on focusing the gene action to the map of the blastoderm, genes lying in the same band proved to function independently (Bgatov et al, 1984). iii) In the in situ hybridization experiments of DNA clones from the D. melanogaster 10A1-2 band to the chromosomes of other species, it has been found that in Drosophila of the virilis group they are located in at least two distant bands (Umbetova et al, 1988;Kokoza et al, 1990).…”