ArticleSchaer JC, Maurer U, Schindler R.
Exp Cell Biol. 1978;46(1-2):1-10.
Thymidine concentrations in serum used for cell culture media were determined with an assay based on isotope dilution. In this assay, incorporation of (3H)-thymidine into DNA of cultured cells was measured in the presence of 5 and 20% serum as a function of the concentration of unlabeled thymidine added to the medium. In three batches of horse serum, thymidine concentrations were 0--0.17 micron, while in fetal calf serum values of 0.75--2.1 micron were obtained. Dialysis of serum resulted in a reduction of thymidine levels by factors of at least 10.