[The phenomenon of RNA interference and development of organism]. / Iavlenie RNK-interferentsii i razvitie organizma.

RNA interference consists in specific mRNA degradation in response to introduction of a double-stranded RNA, homologous in nucleotide sequence. RNA interference was found in eukaryotes and is used in genomics as a powerful method to determine the functions of genes with known nucleotide sequences. RNA interference is considered as a tool of protection against viruses and harmful consequences of mobile elements' transposals. The involvement of the components of RNA interference is considered in spermatogenesis of Drosophila melanogaster and regulation of the expression of genes in Caenorhabditis elegans responsible for temporal patterns of development. The role of RNQA interference in stem cell formation and functioning is also considered.

[Role of double-stranded RNA in eukaryotic gene silencing]. / Rol' dvukhtsepochechnoi RNK v podavlenii ékspressii genov éukariot.

Data on RNA interference, that is, posttranscriptional gene silencing by homologous double-stranded (ds) RNA, are reviewed. Gene silencing caused by exogenous dsRNA in artificial systems and observed in transgenic organisms carrying additional gene copies is considered. Data are summarized on the mechanism that arose during evolution of the Drosophila melanogaster genome to suppress repetitive genes with the use of dsRNA and thereby to prevent male sterility. The role of dsRNA in inhibiting expression and transposition of mobile elements is discussed on the basis of authors own and published findings.

[Inhibition of gene expression by administration of homologous double-stranded RNA in Drosophila melanogaster cell culture]. / Podavlenie ékspressii genov vvedeniem gomologichnoi dvutsepochechnoi RNK v kul'ture kletok Drosophila melanogaster.

Specific inhibition of gene expression by exogenous homologous double-stranded RNA (dsRNA) in invertebrates and in the early development of vertebrates is termed RNA interference. Cultured cells were cotransfected with reporter plasmids and dsRNA. The inhibitor effect on reporter gene expression depended on the extent of homology between dsRNA and the target gene. RNA interference was also studied in cells cotransfected with plasmids directing synthesis of sense and antisense RNAs. Production of antisense RNA only slightly inhibited expression of the reporter gene. Simultaneous expression of both sense and antisense RNAs from a special plasmid did not inhibit expression of the reporter construct.

[The tissue localization and secretion of mucin-D in Drosophila melanogaster]. / Tkanevaia lokalizatsiia i sekretsiia mutsina-D Drosophila melanogaster.

Glycoprotein with biochemical characteristics that allow us to classify it as a glycoprotein of mucin-type was isolated from cultured embryonic cells of Drosophila melanogaster. This is the first finding of mucin-type glycoprotein in insects. Using high-affinity monoclonal antibodies against a carbohydrate epitope, we demonstrated that the accumulation of this glycoprotein in the culture fluid of Drosophila cell line and cultured cells of other insects was inhibited by secretion inhibitors. 20-hydroxyecdysone, a hormone responsible for molting and metamorphosis in insects, inhibits the accumulation of this glycoprotein in the culture fluid, as well as in cells of Drosophila Dm cell line. In another cell line (Schneider-2), where there was practically no secretion of this glycoprotein, the hormone induced its increased accumulation in the cells. Mucin glycoproteins recognized by monoclonal antibodies have been found in embryos, imaginal disc, fat body, testicles, and ovaries, but not in salivary glands or muscles of Drosophila.

[Glycoproteins from Drosophila melanogaster cell culture contains O-bound carbohydrate chains of the Gal(beta1-3)GalNAc type]. / Glikoprotein iz kul'tury kletok Drosophila melanogaster soderzhit O-sviazannye uglevodnye tsepi tipa Gal(beta1-3)GalNAc.

The glycoprotein from cultured cells of D. melanogaster, also detected in various insect tissues as a component of the extracellular matrix, was characterized as a mucin-type glycoprotein not yet described in invertebrates. This glycoprotein with an apparent molecular mass of approximately 90 kDa contains about 40% of carbohydrates, largely represented mainly by GalNAc and Gal; its polypeptide moiety is enriched with Thr, Ser, Pro and Gly. An analysis of oligosaccharides liberated by treatment of the glycoprotein with alkaline NaBH4 or O-glycanase (endo-alpha-N-acetylgalactosaminidase) revealed Gal(beta 1-3)GalNAc as the major type of the sugar chains. About half of the Thr + Ser residues in the glycoprotein were estimated as O-glycosidically linked with the disaccharide units.

[Glucose-6-phosphate dehydrogenase of Drosophila melanogaster: purification and some properties of normal and mutant enzyme forms]. / Gliukozo-6-fosfatdegidrogenaza Drosophila melanogaster: ochistka i nekotorye svoistva fermenta v norme i pri mutatsiiakh.

Two isozymes of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) (G6PD) of Drosophila melanogaster encoded by allelic genes were purified 3000-fold by biospecific phosphocellulose chromatography, using NADP as the enzyme eluent. Electrophoretically fast isozyme A and slow isozyme B variants prove to contain identical subunits with molecular weight of 54000-55000. G6PD is shown to be a dimer. An antiserum directed to highly purified isozyme A does not inhibit the activity of both isozymes. The mutant forms of G6PD restoring the viability of flies without 6-phosphogluconate dehydrogenase show drastically increased Km values for NADP and/or glucose-6-phosphate. It was demonstrated for two mutations that a sharp (200-fold) magnification of Km value for the substrate followed by a considerable increase in the enzyme thermostability might not exert any essential influence on the Km value for NADP.

[Purification and various biochemical and immunological properties of wild and mutant forms of Drosophila melanogaster 6-phosphogluconate dehydrogenase]. / Ochistka i nekotorye biokhimicheskie i immunologicheskie svoistva 6-fosfogliukonatdegidrogenazy Drosophila melanogaster v norme i v sluchae mutatsii.

A 1500--2000-fold purification procedure using substrate elution from phosphocellulose is described for two isozymes of 6-phosphogluconate dehydrogenase (6PGD) coded for by the corresponding allelic genes. Taking into account the data of gel filtration and of SDS polyacrylamide gel electrophoresis both isozymes are shown to be dimers containing identical polypeptides of mol. weight 50 000. Antisera against the highly purified sample of 6PGD, inactivated by lyophilization completely inhibited the enzyme activity. Antigens reacting to antisera were revealed by Ouchterlony immunodiffusion tests in extracts of flies carrying the wild type or mutant Pgd allele, coding for 6PGD. In addition to 6PGD antigen (antigen 1) another protein (antigen 2) which shared no common antigenic precipitative determinants with the antigen 1 was revealed in extracts of the normal flies. Antigen 2 was demonstrated also in the six different mutants which expressed zero level of 6PGD activity and had no antigen 1. Mol weight of a 6PGD subunit and of antigen 2 purified by immobilized antibodies were shown to be identical by SDS-polyacrilamide gel electrophoresis. A transformation of "antigen 2" to "antigen 1" was performed by treatment of the former in 2% SDS-mercaptoethanol solution. As a result of SDS treatment no changes of antigenic properties of the inactivated and dissociated 6PGD dimers were observed in immunodiffusion tests.

[Nature of mutations disrupting the formation of 6-phosphogluconate dehydrogenase in Drosophila melanogaster, and their suppression]. / Priroda mutatsii, narushaiushchikh obrazovanie 6-fosfogliukonatdegidrogenazy u Drosophila melanogaster, i ikh supressiia.

Molecular nature of lethal and semilethal mutations in the Pgd locus of D. melanogaster coding for 6-phosphogluconate dehydrogenase (6tpgd) was studied. All these mutations affect the structural gene of the Pgd locus: 3 semilethal mutations resulted in altered 6PGD molecules with the decreased catalytic activity; the remaining 8 lethals were "zero" alleles possessing mutant polypeptides inactive but capable to react with antisera against highly purified 6PGD. "Zero" or low activity alleles for glucose-6-phosphate dehydrogenase induced by ethyl methansulfonate were shown to be supressors for the lethal mutations in the Pgd locus. A monocistronic type of organization of the Pgd locus is suggested taking into account the biochemical mechanism of supression of the Pgd-lethals and their location in the structural gene coding for 6GPD.