[The temperature sensitivity of mutations in species of the virilis group of Drosophila. II. The effect of temperature on the maternal effect on the puffed marker following hybridization].

The influence of temperature (17 and 31 degrees) on the maternal effect of mutation Puffed (Pu) in Drosophila hybrids has been studied. In the hybrids female D. littoralis +/+ x male D. virilis Pu/Pu, the stage of formation of black ring on anterior spiracles in the 3rd larval instar is sensitive to 31 degrees. In the hybrids female D. virilis Pu/Pu x male D. littoralis +/+, the expression of Pu gene manifests the maternal effect and as a result, two temperature-sensitive stages are found. The first one--onset of embryogenesis (2 to 4 hrs). At the temperature 17 degrees, the penetrance of Pu increases. The second stage is sensitive to 31 degrees and coincides with the period of black rings formation on anterior spiracles in the 3rd laval instar. It has been shown that at least two genetic systems take part in the formation of this feature. One group of genes controls the maternal effect and is sensitive to low temperature in the early embryogenesis of the hybrids female D. virilis x male D. littoralis. The second one--Pu gene and its modifiers--is active during the 2nd half of the 3rd larval instar and is heat-sensitive.