Low pH leads to sister-chromatid exchanges and chromosomal aberrations, and its clastogenicity is S-dependent.
The effect of low pH on sister-chromatid exchanges (SCE), chromosomal aberrations (CA), and the cell cycle were investigated in Chinese hamster cells. The cells were treated in media over the pH range 7.2-5.4 during 24-h continuous or 3-h pulse treatments. In Chinese hamster ovary K1 cells, slight increases in SCE frequency were induced by 3-h pulse treatment with a 28-h recovery time. In Chinese hamster V79 379A cells, similar slight increases in SCE frequency were observed with both treatments. A severe delay in the cell cycle was noted in both cell types. DNA analysis with flow cytometry indicated that the cell cycle delay occurred in S phase. CA were observed in the first metaphase. Multiple fixation times over a 27-h period were used to determine whether or not CA could be induced in cells exposed to low pH medium in more than one part of the cell cycle. Only a few chromatid gaps were induced when the cells were fixed at 0-9 h after the 3-h treatment, most probably representing cells that were treated in their G2 or late S phase. CA were induced in cells fixed between 12 and 27 h after the 3-h treatment. These cells were most probably treated in early S phase, in G1, or in the previous G2/M. These results suggest that low pH clastogenicity is S-dependent.
Morita
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Tsukuba Research Laboratories, Nippon Glaxo Ltd., Ibaraki, Japan.
D000818:Animals; D016466:CHO Cells; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D002869:Chromosome Aberrations; D006224:Cricetinae; D003470:Culture Media; D005434:Flow Cytometry; D005821:Genetic Techniques; D006863:Hydrogen-Ion Concentration; D016296:Mutagenesis; D016196:S Phase / Q000235:genetics*; D012854:Sister Chromatid Exchange
D003470:Culture Media