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

Abstract

The X chromosome region 9F12-10A7 (7 bands removed by Df(1)VL3) was saturated with lethal, semi-lethal, visible and male sterile mutations A total of 11 complementation groups were found. In the more narrow interval of Df()1)VL1 which removes 3 bands (10A1-2, 10A3, 10A4-5) 6 loci were localised. - The band 10A1-2 consists of a sereis of 5 different subunits: (i) silent DNA where no functions were found - at the distal edge of the band; (ii) and (iii) two genes: v and 1(1)BP4; (iv) silent DNA in middle of the band, (v) locus sev on the proximal edge of the band. About 70% of the band's DNA was found to be silent. - Using the set of chromosome rearrangements removing different parts of the band it was shown that these five sequences may function independently from each other.

Identical Functional Organization of Nonpolytene and Polytene Chromosomes in Drosophila melanogaster

“…Under the light microscope, in the context of a normal X chromosome, the band 10A1–2 appears as a “single large dense body even if the chromosome is well-stretched” [57], [58], however according to the EM data [4], [55] this region in fact harbors five distinct bands. There is one prominent band 10A1–2, and four medium-sized bands, two found distal (9F12 and 9F13, Fig.…”

“…According to the combined cytogenetic and molecular-genetic analysis, the region of polytene chromosome band 10A1–2 is marked with two genes, vermilion which is located at its distal end [55], [57], [58], and sevenless , at its proximal side [4], [55]. Therefore, we used positions of these two genes on the physical map as starting points for mapping the region in nonpolytene chromosomes.…”

“…Here, we perform analysis of bands and interbands in the region 10A1–2 – 10B1–2, very well characterized cytology- and genetics-wise before [4], [55], in polytene chromosomes from salivary gland cells and interphase chromosomes of mitotically dividing cells. Our results demonstrate high similarity of the banding patterns in both polytene and non-polytene chromosomes.…”

Chromomeric organization of polytene chromosomes

“…Kozlova, E.B. Kokoza, I. Tretyakova, manuscript in preparation) seen as 7 bands in which 12 genes have been revealed (Zhimulev et al, 1981b. Moreover, in 7 DNA fragments in which genes have not been revealed by mutation tests, complementation has been found to poly(A)+RNA or cDNA clones.…”

“…The smallest size of the transformed DNA which is still seen as a band is 5kb. Zhimulev et al, 1981Zhimulev et al, , 1987. Dp (1) The degree of DNA packing in the inactive band was close to the superbead level and corresponds to that of a fibril of 30 nm in diameter.…”