[The absence of DNA methylase activity in Drosophila cells].

DNA methylase activity has been studied in partially purified extracts from cultured cells, embryos, and adult Drosophila flies. No significant level of transfer of methyl groups from S-adenosylmethionine with formation of 5-methylcytosine and 6-methyladenine was observed. Methylase activity in Drosophila cells as compared to bovine lymphocytes and rat liver is either absent or at least 5000-15,000 times lower and hence cannot be detected using the present method.

[Intensification of lymphocyte blast transformation inhibition by chorionic gonadotropin in combination with glucocorticoids].

The effect of chorionic gonadotropic hormone (CGH) alone or combined with glucocorticoids (prednisolone, hydrocortisone, urbasone and dexasone), applied in clinical practice as immunodepressants, on lymphocyte transformation was studied in vitro during lymphocyte stimulation by phytohemagglutinin (PHA). The synthesis of DNA was estimated from 3H-thymidine incorporation. The results obtained were expressed in per cent of the label incorporation into the test cultures compared to non-stimulated control.

[The effect of alpha- and beta-ecdysone on differentiation of imaginal disks of Drosophila melanogaster cultivated in vitro].

The effect of alpha- and beta-ecdysone was studied upon differentiation of eye and leg imaginal discs of Drosophila cultivated together with neural ganglia in the medium C-39. In the medium without hormone, eye and leg imaginal discs from larvae of the early 3rd instar are not capable of differentiation. In these conditions, eye imaginal discs from larvae of the late 3rd instar become pigmented in 5 weeks and leg imaginal discs form sometimes segmented limbs on the 4th week of cultivation.

Influence of ecdysterone on the growth of cells and synthesis of macromolecules in established cell lines of Drosophila melanogaster.

Ecdysterone (beta-ecdysone) and 2-deoxy-alpha-ecdysone specifically inhibit the growth of established embryonic cells of D. melanogaster. A preparation of alpha-ecdysone is 100 times less active than ecdysterone.