| Abstract: | The thermosensitivity and thermosensitive period of the genes controlling the elimination of the 6th chromosome of D. littoralis in the hybrids male D. virillis X female D. littoralis were studied. The appearance of flies with the mutation glossy (mosaics and haplo-6-flies) served as a criterion of chromosome elimination. The genes under study were shown to be cold-sensitive, monophasic. The thermosensitive period lasts 2.5 hrs after egg laying--from the 1st cleavage division till the beginning of migration of the nuclei in the egg cortex. The appearance of almost 100% of haplo-6-flies at at 17 degrees is accounted for by the synchronous elimination of the 6th chromosome of D. littoralis during the first 3 cleavage divisions. The appearance of mosaics at 25 degrees is accounted for by the asynchronous chromosome elimination. |
