chromosome
chromosome (with mu2PL00250)
mu21 and mu21/Df(3L)Aprt-1 mutants have a similar frequency of single-strand annealing repair (SSA) compared to controls in a P{wIw.FRT} hemizygous assay to study DNA double-stranded break repair when assayed at 38oC, but show an increased SSA frequency compared to controls when assayed at 32oC.
Homozygous larvae do not show higher sensitivity to killing by methyl methanesulfonate or radiation than wild type. mu21 shows a 6-fold increase in the frequency of total y- and f36a spots and a 17-fold increase in the frequency of twin spots in the abdomen of unirradiated y- + / + f36a females compared to controls. γ irradiation has no discernible effect on the frequency of spots in mu21 females in contrast to wild type.
Lesions induced by γ rays in sperm chromosomes are repaired after fertilisation, while lesions induced in oocyte chromosomes are shunted instead to a mechanism that stabilises broken chromosome ends.
Irradiation of females homozygous for mu21 with low doses of X rays produces substantial numbers of terminal deficiencies for all chromosome arms <up>see for example Df(1)yT</up>; irradiation of heterozygous females produces frequencies of deficiencies intermediate between those obtained from homozygous mu21 and wild-type females. Extents of deficiencies limited only by the ability to recover them in viable offspring. Incidence of terminal losses linear with dose; such deficiencies visible cytologically and can be shown by in situ hybridization to lack sequences characteristically present at the termini of chromosome arms. Irradiation of mu21 females does not increase the incidence of either interstitial deficiencies or sex-linked lethal mutations. Irradiation of mu21 males does not increase the frequency of deficiencies.
M.M. Green.
Df(3R)sbd105 fails to complement mu21.