title: Features of the structure of replicating and non-replicating chromatin in chicken erythroblasts.
abstract: The digestion by DNAase I of DNA synthesised by isolated chicken erythroblasts was examined in isolated nuclei. It was found that newly synthesised DNA was susceptible to DNAase I but matured to a relatively resistant form with increasing time after replication as observed in mammalian systems. The presence of trypsin in the digestion exposed all of the DNA to DNAase I action. Examination of the digestion products showed that the newly replicated DNA differed little from the more mature form in the structure of the DNA-protein complex but that the difference in susceptibility was probably a result of a differential rate of access of the DNAase to the new and old DNA.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002645:Chickens; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004261:DNA Replication; D003851:Deoxyribonucleases / Q000378:metabolism*; D004900:Erythroblasts / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D014357:Trypsin
chemical_list: D002843:Chromatin; D004247:DNA; D003851:Deoxyribonucleases; D014357:Trypsin; D008274:Magnesium; D002118:Calcium; D013936:Thymidine