Hypersensitivity of DNA in transcriptionally active chromatin to ionizing radiation.
We have examined the size distribution of single-strand fragments of total 3H-labeled DNA and of DNA sequences complementary to specific probes in gamma-irradiated and unirradiated mouse L929 cells. Those DNA sequences which hybridize to rDNA or to poly(A+)RNA have lower number average molecular weights and sustain 5--6-times the number of single-strand breaks as do satellite DNA sequences or the bulk DNA. We therefore conclude that transcriptionally active DNA sequences are more susceptible to ionizing radiation-induced damage than are inactive sequences, and suggest that these differential susceptibilities are a likely consequence of differences in their chromatin organization.
D000818:Animals; D002843:Chromatin / Q000378:metabolism / Q000528:radiation effects*; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004275:DNA, Ribosomal; D004276:DNA, Satellite / Q000235:genetics; D004277:DNA, Single-Stranded / Q000528:radiation effects*; D005260:Female; D007739:L Cells / Q000378:metabolism / Q000528:radiation effects; D051379:Mice; D010957:Plasmids; D011061:Poly A / Q000235:genetics; D012313:RNA / Q000235:genetics; D012333:RNA, Messenger; D014158:Transcription, Genetic / Q000528:radiation effects*; D014981:Xenopus
D002843:Chromatin; D004275:DNA, Ribosomal; D004276:DNA, Satellite; D004277:DNA, Single-Stranded; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D004247:DNA