[The characteristics of the expression of temperature-dependent dominant lethal mutations in Drosophila melanogaster].

The results of a series of investigations on obtaining and analysing dominant temperature-sensitive lethals (DTS-lethals) are summarized. Using EMS, both cold- and heat sensitive mutations of this type were induced in large autosomes. The cold-sensitive mutations of chromosome 3 were revealed for the first time. The effect of genetic phone on DTS lethal penetrance and expressivity was studied. The character of expression of two mutations possessing a pleiotropic action was examined. The heat-sensitive 1(2)M90DTS mutation disturbed the structure of abdominal tergites in all imago and, besides, caused an abrupt decrease in the female reproductive period. The pattern of alterations observed in oogenesis along with the result of phenogenetic analysis suggest that this gene takes part in the genetic control over the proliferation of stem oogonial cells. The cold-sensitive 1(2)M66DCS mutation caused a number of disturbances in imago thoracic structures: inability to flight, raised up wings, extremity fracture, etc. Mutant flies showed serious disorders of indirect flight muscles both at morphological and at ultrastructural levels. It was established that this mutation was a cold-sensitive allele of Mhc gene which controls the synthesis of myosine heavy chains in drosophila.