Infrequent chromosome aberrations in Syrian hamster cells following partial synchrony by amino-acid deprivation

Incubation of Syrian hamster embryo secondary cell cultures in isoleucine or arginine deficient medium inhibited cell multiplication; 4-7% of the cells were synthesizing DNA compared to approximately 40% for cells in complete medium. After the deficient medium was replaced with complete medium, cells resumed multiplication and within 12 hours 65--70% of the cells entered into the S phase. A second peak of labeled cells, approximately 55%, occurred 24 hours after addition of complete medium. Chromosomal damage characteristic for cell lines grown in amino acid deficient medium did not occur with these Syrian hamster cells. Isoleucine or arginine deprivation resulted in chromosomal or chromatid aberrations in only 2-5% of the cells, whereas chromosomes of control cells in complete medium occasionally exhibit chromatid gaps (less than 1% of the cells).