Effect of ethanol pretreatment on genetic damage induced by X-rays in Drosophila melanogaster sperm

Drosophila melanogaster males were treated with 96% ethanol for 45 min by means of soaked tissue paper placed at the bottom of regular culture vials before being exposed to 2 krad of X-rays. The use of ethanol was dictated by its high efficiency to scavenge hydroxyl radicals that play a substantial role in the indirect effect of ionizing radiation. The data obtained show that the frequency of sex-linked recessive lethals, reciprocal translocations and chromosome losses induced in postmeiotic cells were not reduced by ethanol pretreatment. Rather, in the combined treatments a significant increase in II-III translocations was observed in sperm. This effect declined in late and mid spermatids. Treatment with ethanol alone did not modify the frequencies of the genetic endpoints tested. It is tentatively suggested that: (i) ethanol or ethanol radicals impair the restitution of broken chromosome ends, thereby increasing the chances for rearrangement formation in the egg, or (ii) ethanol given prior to irradiation acts as a weak dose-modifying factor. If so, a slight increase in the effective dose could have resulted in a detectably higher frequency of translocations whose induction, unlike the other genetic damages investigated that increase linearly with dose, follows the slope of a 2-hit kinetic curve.