The purpose of this investigation was to study the effect of acute γ-irradiation of parent adults on the endoreduplication of giant chromosomes in F1 generation of Drosophila melanogaster Meig. A wild-type Oregon-R strain was used as the material. Virgin females and males of Drosophila adults at the age of 3 days were irradiated with doses of 8, 16 and 25 Gy. Giant chromosomes were studied by cytomorphometry on squashed preparations of Drosophila salivary glands stained with acetoorsein. The preparations were obtained at late third instar larvae. The mean values of the polyteny degree of chromosomes (PDC) in males increased after 8 Gy by 10.6%, after 25 Gy by 7.4%, and did not change after the dose of 16 Gy. In females, the PDC did not differ from the control irrespective of the irradiation dose. An increase in endoreduplication was also evidenced by the accelerated development of offsprings of both sexes after irradiation of parents with 25 Gy, and in males also at a dose of 16 Gy. The statistical impact of power of radiation on polyteny was 26.8%, while the impact of sex was 4.9%. The impact of power of radiation on the developmental rate of offspring was 4.4% in males and 7.5% in females. The enhancement of endoreduplication is considered as a consequence of increasing selection pressure after irradiation. The possible involvement of epigenetic effects in the effect of ionizing radiation on endoreduplication is discussed.

中文翻译：

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果蝇暴露于急性γ射线后，果蝇后代的核内复制。

这项研究的目的是研究对成年果蝇进行急性γ射线照射对果蝇F1代中巨大染色体的核内复制的影响。使用野生型Oregon-R菌株作为材料。用8、16和25 Gy的剂量辐照3天大的果蝇成年雌性和雄性。通过细胞形态测定法对用丙酮精染色的果蝇唾液腺的压榨制品进行巨染色体研究。该制剂是在第三龄幼虫幼虫时获得的。男性的染色体多态性（PDC）平均值在8 Gy后增加了10.6％，在25 Gy之后增加了7.4％，并且在16 Gy剂量后没有变化。在女性中，无论辐照剂量如何，PDC与对照都没有差异。父母对25 Gy的辐照后，以及在雄性也对16 Gy辐照后，两性后代的发育加快也证明了核内复制的增加。辐射强度对多态性的统计影响为26.8％，而性别的影响为4.9％。辐射功率对后代发育速度的影响，男性为4.4％，女性为7.5％。核内复制的增强被认为是照射后选择压力增加的结果。讨论了表观遗传效应可能参与电离辐射对核内复制的影响。而性别的影响为4.9％。辐射功率对后代发育速度的影响，男性为4.4％，女性为7.5％。核内复制的增强被认为是照射后选择压力增加的结果。讨论了表观遗传效应可能参与电离辐射对核内复制的影响。而性别的影响为4.9％。辐射功率对后代发育速度的影响，男性为4.4％，女性为7.5％。核内复制的增强被认为是照射后选择压力增加的结果。讨论了表观遗传效应可能参与电离辐射对核内复制的影响。