Heat-induced lethality and chromosomal damage in synchronized Chinese hamster cells treated with 5-bromodeoxyuridine.

Abstract

SummarySynchronous Chinese hamster cells exposed to heat treatments of 45·5°c were very sensitive during S phase when chromosomal damage could account for cell killing, i.e. as for x-irradiated cells, the 37 per cent survival value for heated cells was observed when there was about one aberration per cell. However, the aberration frequency was very low and could not account for cell killing when the cells were heated, either during mitosis when they were most sensitive in terms of lethality, or during G1 when they were most resistant. Furthermore, about 50 per cent of the deletions in these cells heated in mitosis or G, occurred at the secondary constriction of the X chromosome. Incorporation of BUdR into DNA prior to synchronizing the cells had only an additive interaction with heat administered during G1 or S. This interaction was characterized by a reduction in the shoulder of the dose-response curves observed for both chromosomal aberrations and cell killing.These findings contrast greatly with those ...