Subphases of DNA replication in Drosophila cells.
Exponentially growing Drosophila S2 cells in suspension culture were synchronized at low- and high-resolution centrifugal elutriation, and DNA synthesis was measured by [(3)H]-thymidine incorporation throughout the S phase. At low resolution, one repair peak at the G(1)/G(0) border and two replication peaks known as early and late S subphases were observed. At high resolution, six chronologic compartments were distinguished. The distribution of these peaks indicated one repair peak at 2.05 C value, one minor replication peak at 2.43C, and four major subphases of replication corresponding to 2.64C, 2.89C, 3.32C, and 3.60C, representing 6.7%, 3.4%, 15.3%, 20.4%, 32.1%, and 22.0% of the synthetic activity, respectively. The five major peaks of cell growth with 2.32C, 2.56C, 2.85C, 3.18C, and 3.58C values consistently preceded those of replication subphases.
Rehak
M
M
Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
Csuka
I
I
Szepessy
E
E
Banfalvi
G
G
D000818:Animals; D002452:Cell Count; D002455:Cell Division; D002460:Cell Line; D002469:Cell Separation / Q000379:methods; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication; D004330:Drosophila / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D016196:S Phase / Q000235:genetics*; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D014316:Tritium; D004247:DNA; D013936:Thymidine