Consequences of accounting for isotopic dilution in thymidine incorporation assays

Rates of thymidine incorporation into DNA were corrected for isotope dilution by internal nucleotide pools and were compared with rates obtained from uncorrected data. Differences as large as 109% were observed between corrected and uncorrected estimates of thymidine incorporation. The degree of underestimation varied seasonally and, to a lesser extent, spatially.