Localization by Q-banding of mitotic chiasmata in cases of Bloom's syndrome.
The distribution of mitotic chiasmata from the lymphocytes of three patients with Bloom's syndrome was studied by Q-banding. An estimate was made of the average brightness of the human chromosomes and of the brightness and length of the Q-regions. A strong relationship was found between the average darkness of a chromosome and its chiasma density. The shorter and darker Q-regions contained more chiasmata, with the exception of the chromosome tips which had lower chiasma densities. A few "hot spots" had particularly high chiasma densities. Centric regions contained 17% of the chiasmata. The data are consistent with the assumptions that chiasmata are favored in darker regions and at borders between light and dark regions.
D000015:Abnormalities, Multiple / Q000473:pathology*; D004392:Dwarfism / Q000473:pathology; D005148:Facial Dermatoses / Q000473:pathology*; D005260:Female; D006801:Humans; D008214:Lymphocytes; D008297:Male; D008938:Mitosis; D013577:Syndrome; D013684:Telangiectasis / Q000473:pathology*