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V A Gvozdev

Publications and source records attributed to V A Gvozdev.

At least 55 records · Page 3Linked to original sources
PubMed1987

[Transposition of mobile dispersed genes (MDG) after substitution of various chromosome pairs in inbred Drosophila melanogaster strains].

Transpositions of MDG-1, MDG-3 and copia were detected as a result of crosses of the inbred maladaptive LA stock with laboratory stocks, in order to construct the genomes carrying different combinations of the LA or non-La chromosomal pairs. Changes of the mobile gene distributions were revealed in chromosomes of hybrid genotypes, as compared to parental chromosomal pairs. A trivial source of variability of chromosomal molecular structure ensured by crossing over was excluded by inversions which serve as suppressors of crossing over in corresponding crosses. Multiple transpositions of mobile genes in definite chromosomal sites were detected in genotypes carrying chromosomal pair 2 originated from the LA stock. No such transpositions were observed, when the pair 2 was substituted by the chromosome 2 originated from the Swedish-b line or in control crosses, where the LA stock was not involved. Both LA chromosomes 2 and 3 were shown to be the targets of transpositions. Comparison of hot spot transposition sites of MDG-1, as a result of crosses, with the earlier described rare events of spontaneous transpositions in the LA stock, coupled with its fitness increase, revealed that the hot spot sites were shared in both series of experiments. The data obtained show that transpositions of mobile genetic elements may change the genetic and molecular structure of the chromosome involved in crosses, in spite of suppression of crossing over by inversions usually suggested as a tool for keeping chromosomal genetic structure intact.

Animals↗
PubMed1986

Concerted transpositions of mobile genetic elements coupled with fitness changes in Drosophila melanogaster.

In an inbred low-activity (LA) strain of Drosophila melanogaster with a low level of fitness and a complex of inadaptive characters, in situ hybridization reveals an invariant pattern of distribution of three copia-like elements (mdg-1, mdg-3, and copia). Rare, spontaneous, multiple transpositions of mobile elements in the LA strain were shown to be coupled with a drastic increase of fitness. A changed pattern of various types of mobile elements was also observed on selecting the LA strain for higher fitness. High-fitness strains show transpositions of mobile elements to definite chromosomal sites ("hot spots"). Concerted changes in the location of three different mobile elements were found to be coupled with an increase of fitness. The mdg-1 distribution patterns were also examined in two low-fitness strains independently selected from the high-fitness ones. Fitness decrease was accompanied by mdg-1 excision from the hot spots of their location usually detected in the high-fitness strains. The results suggest the existence of a system of adaptive transpositions of mobile elements that takes part in fitness control.

Animals↗
PubMed1982

Transpositions of mobile dispersed genes in Drosophila melanogaster and fitness of stocks.

In situ hybridization with polytene chromosomes was used to demonstrate the transposition of mobile dispersed genes (mdg)-1 and 3 following the selection of flies from low reproductive activity and viability (LA stock) for high reproductive activity, viability and fitness (LA+ and HA stocks). The inbred LA stock is continuously selected for low reproductive activity and viability and maintains at least for twenty-five generations a characteristic pattern of mdg-1 distribution in 14-15 sites. Inbred LA+ and HA stocks exhibit a changed pattern of mdg-1 locations and the number of sites reaches 21-25. Parallel and independent selection for higher viability may lead to similar characteristic changes in the localization of mdg-1. In several independent experiments we observed, within one generation, a spontaneous and saltatory growth of viability and fitness in the mass-bred LA stock. In these cases new mdg-1 and mdg-3 sites reproducibly appeared to within several bands, some of them characteristic of LA+ and HA stocks. We discuss the possible role of mdg in determining the quantitative characters of individuals and their fitness.

Animals↗
PubMed1981

[Glucose-6-phosphate dehydrogenase of Drosophila melanogaster: purification and some properties of normal and mutant enzyme forms].

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.

Alleles↗
PubMed1980

Transcription of intercalary heterochromatin regions in Drosophila melanogaster cell culture.

Labelled RNA preparations (total newly synthesized RNA, as well as stable cytoplasmic RNA) isolated from a cell culture of D. melanogaster were hybridized in situ with polytene chromosomes. Apart from the nucleolus, in all cases the regions adjacent to the chromocentre in the polytene chromosomes and the intercalary heterochromatin regions in the X chromosome and the autosomes are the most intensively labelled. In the case of asynapsis of polytene chromosomes in heterozygotes the label is detected in a number of intercalary heterochromatin sites in one homologue only ("the asymmetrical label"). The same kind of radioactivity distribution in intercalary heterochromatin regions was observed after a hybridization of polytene chromosomes with cloned DNA fragments (Ananiev et al., 1978, 1979) coding for the abundant classes of messenger RNA (Ilyin et al., 1978) in a cultured D. melanogaster cells. In some regions of intercalary heterochromatin which do not contain these fragments the "'asymmetrical" type of label distribution is observed after hybridization with cell RNA. - These results lead one to regard the intercalary heterochromatin regions as "nests" comprising different types of actively transcribable genes, the composition of each nest varying in different stocks of D. melanogaster.

Animals↗
PubMed1980

[Transcription of portions of chromosomes corresponding to regions of intercalary heterochromatin in Drosophila melanogaster cell cultures].

Labelled RNA preparations (total newly synthesized RNA, as well as stable cytoplasmic RNA) isolated from a cell culture of Drosophila melanogaster were hybridized in situ with polytene chromosomes. Apart from the nucleolus, in all cases the regions adjacent to he chromocentre in the polytene chromosomes and the intercalary heterochromatin regions in the X chromosome and the autosomes are the most intensively labelled. In the case of asynapsis of polytene chromosomes in heterozygotes the label is detected in a number of intercalary heterochromatin sites in one homologous only ("the asymmetrical label"). The same kind of radioactivity distribution in intercalary heterochromatin regions was observed after a hybridization of polytene chromosomes with cloned DNA fragments (Ananiev et al.,, 1978, 1979) coding for the abundant classes of messenger RNA (Ilyin et al., 1978) in cultured D. melanogaster cells. In some regions of intercalary heterochromatin which do not contain these fragments the "asymmetrical" type of labelled distribution is observed after hybridization with cell RNA. These results lead one to regard the intercalary heterochromatin regions as "nests" comprising different types of actively transcribable genes, the composition of each nest varying in different stocks of D. melanogaster.

Animals↗
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↗