Abstract
A variant cell line was obtained from Syrian hamster BHK 21 (C-13) cells after twice treatments with EMS and cyclic and continuous selections with 10-2M 5-iodouridine for 5 months. The colony-forming activity, growth rates in the presence of 5-iodouridine, IUdR and BUdR, distribution of chromosome numbers, uptake of 3H-TdR and cell surface properties of the variant cell line were compared with those of the original BHK cell line.
The variant cells were highly resistant to 5-iodouridine and showed cross-resistances to IUdR and BUdR. They grew more slowly and showed a short lag phase in normal medium. They showed a higher growth rate and a shorter doubling time in the presence of 5-iodouridine than in its absence. The variant cells were more severely affected by short-term treatment with irradiated 5-iodouridine than the original BHK cells. Some cells of the variant line had double the chromosome number of the original cells. The variant cells also showed less uptake of 3H-TdR into the cold TCA insoluble fractions than the original cells and differed from the latter in morphology and mutual cohesion. This may be the first observation on the marked cross-resistances of the variant cell line to 5-iodouridine, IUdR and BUdR in cultured mammalian cells.
