Flow cytometric analysis of X-ray sensitivity in ataxia telangiectasia.
Flow cytometric analysis of 5-bromodeoxyuridine (BrdU) incorporation during DNA synthesis was used to characterize the effects of X-rays on cell-cycle kinetics in the DNA-repair deficiency disease ataxia telangiectasia (AT). Cultured fibroblasts from homozygotes (at/at), heterozygotes (at/+) and normal controls (+/+) were either: (1) irradiated, cultured, then pulsed with BrdU and harvested, or (2) pulsed with BrdU, irradiated, cultured and then harvested. Cells were then fixed and stained with both a fluoresceinated monoclonal antibody against BrdU to identify S-phase cells and with propidium diiodide to measure total DNA content. Irradiation of +/+ and at/+ cells induced a similar, transient G2/M arrest detectable within 8 h, which subsequently delayed by 6-8 h the passage of cells into G1 and depleted early S phase. In contrast, at/at cells failed to arrest in G2/M phase and entered the next cell cycle without pausing to repair radiation-induced damage. X-Rays also blocked entry of +/+ G1 cells into S phase, subsequently reducing the total S-phase population. This effect was not observed in at/at cells. These cell-cycle responses to radiation may be of diagnostic use and ultimately may help explain the basic defect in AT.
Rudolph
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NS
Division of Genetics and Mental Retardation Center, Children's Hospital, Boston, MA 02115.
Latt
S A
SA
D000293:Adolescent; D000328:Adult; D001260:Ataxia Telangiectasia / Q000235:genetics*; D001973:Bromodeoxyuridine; D002453:Cell Cycle / Q000528:radiation effects*; D002455:Cell Division / Q000528:radiation effects; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000528:radiation effects; D005434:Flow Cytometry; D005838:Genotype / Q000528:radiation effects; D006801:Humans; D007231:Infant, Newborn; D007399:Interphase / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D008938:Mitosis / Q000528:radiation effects
D004247:DNA; D001973:Bromodeoxyuridine