Cytogenic analysis in Chinese hamster cells chronically exposed to low doses of x rays

GÜERCI ALBA, DULOUT, FERNANDO N, AND SEOANE ANALIA I

INTERNATIONAL JOURNAL OF RADIATION BIOLOGY

Taylor and Francis Health Sciences

Lugar: Canadá; Año: 2003 vol. 79 p. 793 - 799

0955-3002

It should be important to develop simple experimental models to assess the induction of DNA damage inferring the different factors involved under controlled conditions. This paper describes the cytogenetic analysis carried out in Chinese hamster cells sequentially exposed to very low doses of X-rays. Materials and methods: Chinese hamster ovary (CHO) cells were cultured during 14 cycles. Irradiation treatment was performed once per cycle and three irradiation doses were employed: 2.5; 5.0 and 10.0 mSv. Results: Sequential irradiation of CHO cells did not increase the yield of chomatid- or chromosome-type aberrations. However, a significant increase of achromatic lesions (gaps) was found after the first or second X-ray hit with the three doses employed. Conclusions: Results obtained could be considered as an indication that gaps must be included in the analysis of chromosome aberrations by chronic exposure to low level ionizing radiation and that the effect of very low doses of this type of radiation cannot be explained by the same mechanisms involved in the effect of high radiation doses.  The variation in the frequency of gaps as well as the variation in the mitotic index along the fourteen cycles could be an indication of the induction of genomic instability. According to this, continuous rises and falls in the frequency of gaps as well as in the mitotic index can reflect the simultaneous induction of endogenous DNA damage, cell death and cell survival.