Radiation induced deletions in spermatids and spermatocytes ofDrosophila

Summary Males of the composition X^C2/B^S Yy⁺ were collected as prepupae, aged an additional 48 hours, then irradiated with 1000 r and brooded individually for eight days with three virginy w f females each day. Analysis suggests that brood days 1–3 represent the recovery of cells which were predominantly spermatids at the time of treatment, those from brood days 4–6 predominantly spermatocytes, and those from brood days 7–8 predominantly spermatogonia. The highest frequency of loss of individual Y markers and X0 males, as well as the smallest F₁ population size was found in broods 5 and 6, and especially in brood 6. Further analysis suggests that the vast majority of individual Y-marker losses recovered from diploid cells (spermatocytes, spermatogonia) arose independent of inter-Y arm exchange and Y-autosome translocations. In general, the data confirm the suggestive results of other investigators that deletions are recovered most readily from spermatocytes than from any other stage in spermatogenesis.