DNAase I digestion of early, middle, and late S phase replicating DNA in murine leukemia L5178Y cells.
Cellular DNA from a synchronized population of cultured mouse L5178Y cells was labeled with [3H]thymidine at three times during the S stage: early, middle and late S phases. The deoxyribonuclease I digestability of DNA from these three periods in the subsequent cell cycle indicated that the early S phase replicating DNA had higher enzymatic susceptibility at G1 and early S phases than at middle and late S phases, while the middle and late S phase replicating DNA demonstrated a low susceptibility throughout the cell cycle. This suggests that most, if not all, of transcriptionally active DNA is replicated very early in the S phase.
D000818:Animals; D002478:Cells, Cultured; D004261:DNA Replication; D003850:Deoxyribonuclease I; D003851:Deoxyribonucleases; D004720:Endonucleases; D007399:Interphase; D007942:Leukemia, Experimental / Q000378:metabolism*; D051379:Mice; D014158:Transcription, Genetic
D003851:Deoxyribonucleases; D004720:Endonucleases; D003850:Deoxyribonuclease I