CONTENT OF CYTOSKELETON PROTEINS IN OOCYTES OF THIRD GENERATION <i>DROSOPHILA MELANOGASTER</i> FRUIT FLIES OBTAINED AFTER A 44.5-DAY SPACE FLIGHT
Third-stage larvae of the third generation of Drosophila melanogaster Canton S fruit flies were obtained after a 44.5-day flight of spacecraft «Foton-М4» (Russia, 2014). In laboratory, the larvae grew into a third generation of flies. On the second day of emergence ovaries were extracted from female flies (group pF). Similarly, a third generation of flies (group C) was raised in the synchronous experiment. Real-time RT-PCR and Western blotting were used to determine the content of cytoskeletal proteins and mRNA of respective encoding genes. The content of mRNA genes encoding beta (Act57B and Act87E), gamma-actin (Act5C), acting-binding proteins (Arpc3, Tmod, Svil, Fim and Actn), and tubulin (Betatub85D) and tubulin-binding proteins (Msps, T-cp1, Cct5, T-cp1eta) was less in group pF but not in the control group. The relative content of actin cytoskeleton components reduced significantly both in membrane and cytoplasmic fractions in group pF as compared to group C; however, reduction of the cytoplasmic fraction was more dramatic. On the contrary, content of beta-tubilin, a component of the tubulin cytoskeleton, reduced more significantly in the membrane fraction in group pF but not in group C. However, the acetylated tubulin content of ovarian membrane or cytoplasmic protein fraction was found unchanged both in the pF and C groups. The data suggest the presence in animal cells, oocytes specifically, of a mechanism regulating segregation of these proteins depending on external mechanical factors.