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Fine-structure analysis and gentic organization at the base of the x chromosome in Drosophila melanogaster. [X-ray-induced chromosome breakage analysis]

Journal Article · · Genetics; (United States)
OSTI ID:7090225
Genetic organization at the base of the X chromosome was studied through the analysis of x-ray-induced deficiencies. Deficiencies were recovered so as to have a preselected right end anchored in the centric heterochromatin to the right of the su(f) locus. Free ends of deficiencies occurred at any of 22 intervals in Section 20 and in the proximal portion of Section 19 of Bridges' (1938) polytene chromosome map. The distribution of 130 such free ends of deficiencies induced in normal, In(1)sc/sup 8/, and In(1)w/sup m4/ chromosomes suggests that on the single section level, genes are flanked by hot or cold sites for x-ray-induced breaks, and that occurrence of the hot spots is dependent on their interaction with the fixed-end sites in the centric heterochromatin. In the light of these results, it is argued that long heterochromatic sequences separate the relatively few genes in Section 20, and thus endow it with several characteristics typical of heterochromatic regions. Section 20 is considered to be a transition region between the mostly heterochromatic and mostly euchromatic regions of the X chromosome; the differences between them are suggested as being merely quantitative.
Research Organization:
Technion-Israel Inst. of Technology, Haifa, Israel
OSTI ID:
7090225
Journal Information:
Genetics; (United States), Journal Name: Genetics; (United States) Vol. 88:3; ISSN GENTA
Country of Publication:
United States
Language:
English