[The dominant lethal mutation test in the study of genetic risks of continuous exposure to low-dose ionizing radiation].
BACKGROUND
Dissension in data on the effectivity of ionizing radiation at a low-dose rate do not enable to judge the extent of the genetic risk of such exposition. This estimation, however, is especially important in cases of irradiation of female germ cells in which the lesions can cumulate and persist for a long period.


OBJECTIVE
The aim of this study is to judge the mutagenic effectivity of continuous irradiation on the basis of a model experiment founded on the test of dominantly lethal mutations.


METHODS
Sexually mature female ICR mice were continuously irradiated by gama rays at daily dose rates 0.01 and 0.05 Gy to a total accumulated dose of 1 Gy. The frequency of genetic lesions induced by irradiation in dictyotene oocytes was evaluated by means of the test of dominantly lethal mutations within the periods of 1-2 and 21-22 weeks after the ultimation of irradiation.


RESULTS
Continuous irradiation significantly increased the frequency of dominantly lethal mutations in germ cells of female mice. Induced lesions manifest themselves mostly in form of increased values of preimplantation lethality. The level of dominantly lethal mutations persists on a significantly increased level also in the period of 21-22 weeks after the ultimation of irradiation.


CONCLUSIONS
Continuous irradiation of female mice represents a significant risk factor which induces a long-term increase in frequency of genetic lesions in germ cells. The negative selection of lesions in the preimplantation period can be subsequently the cause of decreased reproductive abilities of irradiated animals. (Tab. 1, Fig. 2, Ref. 13.).
Brezáni
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Ustav lekárskej biológie Lekárskej fakulty Univerzity P.J. Safárika, Kosice, Slovakia. salagov@kosice.upjs.sk
D000818:Animals; D005260:Female; D005720:Gamma Rays; D006801:Humans; D051379:Mice; D008813:Mice, Inbred ICR; D009152:Mutagenicity Tests; D009865:Oocytes / Q000528:radiation effects*; D011829:Radiation Dosage