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V A Gvozdev

Publications and source records attributed to V A Gvozdev.

13 recordsLinked to original sources
PubMed1978

Reiterated genes with varying location in intercalary heterochromatin regions of Drosophila melanogaster polytene chromosomes.

The localization of two cloned D. melanogaster DNA fragments in polytene chromosomes was determined by means of in situ hybridization. These different fragments (Dm 225 and Dm 234B) are present in the genome in hundreds copies and contain genes whose transcription yields two different classes in abundant mRNA (Ilyin et al., 1976, 1977; Tchurikov et al., 1978). About 20--30 sites of these genes are demonstrable in the polytene chromosomes of a given stock. There are small but significant variations in the number and localization of these sites among individuals of the same stock. On the other hand, different stocks of D. melanogaster have an utterly different distribution of revealed hybridization sites in the polytene chromosomes. The location of both fragments (Dm 225 and Dm 234) was found to be virtually identical within any given stock of D. melanogaster. 69 sites for localization of Dm 225 or Dm 234 genes were detected in the chromosomes of 11 individuals studied. At least 50 (and up to 62) of them coincide with intercalary heterochromatin regions which are known to be characterized by ectopic pairing, late replication and the presence of "weak spots" in the chromosome. The ability of Dm225 and Dm 234 to code for the "abundant" classes of messenger RNA (Ilyin et al., 1976) and the fact that their location may coincide with the histone and ribosomal genes suggest that intercalary heterochromatin regions are "nests" containing various types of actively transcribable tandem-repeated genes coding for common "household" cell functions.

Animals↗
PubMed1977

Investigations on the organization of genetic loci in Drosophila melanogaster: lethal mutations affecting 6-phosphogluconate dehydrogenase and their suppression.

The molecular nature of lethal and semilethal mutations in the Pgd locus of D. melanogaster coding for 6-phosphogluconate dehydrogenase (6PGD) was studied. All the 11 mutations affect the structural gene of the Pgd locus: 3 semilethal mutations resulted in altered 6PGD molecules with decreased catalytic activities; the rest 8 lethals were "null" alleles characterized by mutant polypeptides capable of reacting with antisera against highly purified 6PGD. "Null" or low activity alleles for glucose-6-phosphate dehydrogenase induced by ethyl methanesulfonate were shown to be suppressores 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 suppression of the Pgd-lethals and their location in the structural gene coding for 6PGD.

Animals↗
PubMed1977

Isolation of eukaryotic DNA fragments containing structural genes and the adjacent sequences.

In Drosophila melanogaster structural genes are located close to moderately reiterated sequences. One of the clones obtained contains the DNA related to intercalary heterochromatin of D. melanogaster. These are individual differences in the distribution of genetic material in polytenic chromosomes of different stocks of D. melanogaster. The techniques that allow isolation of DNA fragments containing structural genes at the beginning, in the middle, or the end of the coding strand have been elaborated.

Animals↗
PubMed1975

Fine genetic structure of the 2D3-2F5 region of the X-chromosome of Drosophila melanogaster.

97 lethal and semilethal mutations were induced by ethyl methanesulfonate, nitrosomethyl urea and gamma-irradiation in the 2D3-F5 region of the X-chromosome of D. melanogaster. Approximately 1 per cent of the tested X-chromosomes carried a lethal in the 2D3-2F5 region. The mutation frequencies per band or DNA content in the region and the whole X-chromosome are equal. Complementation analysis revealed at least 10 functionally independent essential loci in this region including about 10 bands. The data presented in this study support the one band--one gene hypothesis. The Pgd locus coding for 6-phosphogluconate dehydrogenase (6PGD) is mapped in the 2D3 (OR 2D4) band. Isolation of 11 lethal or semilethal point mutations with null or reduced 6PGD activity shows that the Pgd locus is a vital one.

Chromosome Mapping↗
PubMed1975

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. The action of ecdysterone is eliminated when it is removed within 24 h, but after 48 h the inhibiting influence of the hormone becomes irreversible. The diploid line, triploid and tetraploid sublines are sensitive to ecdysterone. The diploid subline with a spontaneously arisen translocation of an X-chromosome to an autosome of the third pair is substantially more resistant to ecdysterone. At 24 h after the addition of ecdysterone, there is a 2-5-fold suppression of the synthesis of total RNA; DNA synthesis is lowered to the same degree only after 48 h. The gross synthesis of proteins, measured according to the incorporation of C 14-lysine, was not suppressed even after 48 h.

Animals↗
PubMedDate not supplied

A new type of organization of the genetic material in eukaryotes.

An investigation of the properties of a number of genes of Drosophila, obtained by cloning recombinant DNAs, led to the detection of a new type of organization of genetic material. It was found that a number of actively working structural genes of Drosophila are represented by a large number of copies, scattered over its chromosomes. Their localization in the chromosomes is variable, although they are always detected in regions of intercalary heterochromatin. The latter evidently is a site of accumulation of various multiple genes.

Alleles↗
PubMedDate not supplied

[Genome organization in eukaryotes].

The review discussed problems of genome organization in the chromosomes of eukaryotes based on the data of genetical and molecular-biological studies. Particular attention is paid to the peculiarities of organization of genetic material in Drosophila. The main (euchromatic) part of the genome is considered as the totality of separate functional units (chromomere, gene loci), which have in the average a higher excess of DNA compared to the sized of the structural gene. The possible ways of internal organization of these units and the role of different types of DNA sequences in their function are discussed. The features of organization and function of the heterochromatic regions of chromosomes consisting of simple sequences of satellite DNA and tandemly repeated genes (polygenes), that code for general cellular functions (similar to the ribosomal genes) are considered. The instability of the number and even the sites of localization of polygenes in the chromosome, which can be determined by the peculiarities of their functions during differentiation of somatic cells is notes.

Animals↗
PubMedDate not supplied

[Purification and various biochemical and immunological properties of wild and mutant forms of Drosophila melanogaster 6-phosphogluconate dehydrogenase].

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.

Animals↗
PubMedDate not supplied

[Nature of mutations disrupting the formation of 6-phosphogluconate dehydrogenase in Drosophila melanogaster, and their suppression].

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.

Alleles↗