The relationship between radiation-induced and transposon-induced genetic damage during Drosophila spermatogenesis

In this paper the authors report a study of the combined effect of X-irradiation and P element transposition on X-linked recessive lethal mutation rate and on dominant lethality induced in the germ line of F1 dysgenic males. The effect on both recessive and dominant lethals was compared in genetically identical dysgenic and nondysgenic hybrids and clusters of mutations were treated statistically by the unweighted method of Engels. The first two broods of sperm tested exhibited a purely additive effect when X-rays and dysgenesis were combined. The third brood showed a somewhat less than additive effect, but no synergism was found. In contrast, the incidence of dominant lethals was synergistic in the last two broods of sperm tested, represented predominantly by spermatids and spermatocytes respectively. In the first brood, that of mature spermatozoa, X-rays had a negative effect in the presence of dysgenesis, showing less damage than expected. 44 refs.; 3 tabs