Human NORs show correlation between transcriptional activity, DNase I sensitivity, and hypomethylation.
Active human ribosomal gene clusters (NORs) are distinguishable from inactive ones by silver staining. By sequentially applying deoxyribonuclease I (DNase I)-directed in situ nick-translation and silver staining to fixed chromosome preparations, we found that active NORs are more sensitive to DNase I than inactive ones. Use of the two restriction isoschizomeres MspI and HpaII to modify the nick-translation technique showed that active NORs are significantly less methylated than inactive ones. Taken as a whole, our results indicate that ribosomal gene activity, DNase I sensitivity, and DNA methylation are closely interrelated.
D004262:DNA Restriction Enzymes; D019003:Deoxyribonuclease HpaII; D003850:Deoxyribonuclease I / Q000494:pharmacology; D006801:Humans; D008745:Methylation; D009697:Nucleolus Organizer Region / Q000378:metabolism / Q000648:ultrastructure; D012335:RNA, Ribosomal / Q000096:biosynthesis / Q000235:genetics; D012834:Silver; D013194:Staining and Labeling; D014158:Transcription, Genetic
D012335:RNA, Ribosomal; D012834:Silver; D004262:DNA Restriction Enzymes; D019003:Deoxyribonuclease HpaII; D003850:Deoxyribonuclease I