[Time of gene activity in ontogenesis of Drosophila. 2. Temperature-sensitive period of SSa-40a mutation in Drosophila melanogaster].

In the mutants aristapedia (ssa-40a) of D. melanogaster, the temperature-sensitive period (TSP) was determined for the effects observed in the thoracic legs (fusion of tarsal segments). The TSP began in the middle of the first and finished in the end of the second quarter of the 3rd larval instar. The TSP for ssa-40a overlapped the TSP for homoeotic transformation of aristae into tarsi but did not overlap the TSP for spineless effects. An attempt is undertaken to consider the state of determinantion on the basis of the hypothesis of autogenous regulation of gene activity.