title: Subclassification of cells in S phase in a partially synchronized cell system.
abstract: A circadian dependent delay in the incorporation of [3H]TdR into DNA, presumably due to variations in the intracellular pool of [3H]TdR derivatives, was found. It seems reasonable to relate this effect to a circadianally varying age distribution of cells in S phase. At any given time the S phase cells showed large variations in DNA synthesis rate, but it was still possible to identify a mean diurnal variation in the DNA synthesis rate. Differences in the ability of S phase cells to incorporate [3H]TdR are also discussed in relation to flow cytometrical measurements, and this contributes to the understanding of the commonly observed phenomenon that flow cytometry estimates of S-fractions are higher than those obtained with autoradiography.
mesh_terms: D000818:Animals; D001345:Autoradiography; D002610:Cheek / Q000166:cytology; D002940:Circadian Rhythm; D006224:Cricetinae; D004247:DNA / Q000096:biosynthesis; D004847:Epithelial Cells; D005434:Flow Cytometry; D007399:Interphase; D007700:Kinetics; D008297:Male; D008647:Mesocricetus; D013936:Thymidine / Q000378:metabolism*
chemical_list: D004247:DNA; D013936:Thymidine