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V N Bolshakov

Publications and source records attributed to V N Bolshakov.

9 recordsLinked to original sources
PubMed1997

One-hundred and five new potential Drosophila melanogaster genes revealed through STS analysis.

Complementation analysis had suggested that the Drosophila melanogaster genome contains approximately 5000 genes, but it is now generally accepted that the actual number is several times as high. We report here an analysis of 1788 anonymous sequence tagged sites (STSs) from the European Drosophila Genome Project (EDGP), totalling 463 kb. The data reveal a substantial number of previously undescribed potential genes, amounting to 6.1% of the number of Drosophila genes already in the sequence databases.

Amino Acid Sequence↗
PubMed1997

Antisense suppression of the putative ribosomal protein S3A gene disrupts ovarian development in Drosophila melanogaster.

The Drosophila melanogaster homologue of the Anopheles gambiae C3 cDNA has been isolated and characterized by sequence analysis. The encoded protein was localized by immunochemical and immunocytochemical methods. The Drosophila C3 protein is highly similar to homologues of disputed function, which have previously been identified in fungi, plants and animals. The protein is ubiquitous and localized in the cytoplasm. Cell fractionation followed by detection with a specific antibody preparation shows that the protein is associated with the 40S ribosomal subunit. The C3 gene is located in section 101F of chromosome 4. Antisense transgenic analysis shows that this gene is essential for oogenesis. The most prominent phenotype resulting from antisense depletion of C3 RNA is disappearance of the follicular cells of the ovary (where the concentration of C3 protein is normally high) and abnormalities of the associated germline derivatives, leading to failure of egg production.

Amino Acid Sequence↗
PubMed1997

P-element insertion alleles of essential genes on the third chromosome of Drosophila melanogaster: correlation of physical and cytogenetic maps in chromosomal region 86E-87F.

We have established a collection of 2460 lethal or semi-lethal mutant lines using a procedure thought to insert single P elements into vital genes on the third chromosome of Drosophila melanogaster. More than 1200 randomly selected lines were examined by in situ hybridization and 90% found to contain single insertions at sites that mark 89% of all lettered subdivisions of the Bridges' map. A set of chromosomal deficiencies that collectively uncover approximately 25% of the euchromatin of chromosome 3 reveal lethal mutations in 468 lines corresponding to 145 complementation groups. We undertook a detailed analysis of the cytogenetic interval 86E-87F and identified 87 P-element-induced mutations falling into 38 complementation groups, 16 of which correspond to previously known genes. Twenty-one of these 38 complementation groups have at least one allele that has a P-element insertion at a position consistent with the cytogenetics of the locus. We have rescued P elements and flanking chromosomal sequences from the 86E-87F region in 35 lines with either lethal or genetically silent P insertions, and used these as probes to identify cosmids and P1 clones from the Drosophila genome projects. This has tied together the physical and genetic maps and has linked 44 previously identified cosmid contigs into seven "super-contigs" that span the interval. STS data for sequences flanking one side of the P-element insertions in 49 lines has identified insertions in the alphagamma element at 87C, two known transposable elements, and the open reading frames of seven putative single copy genes. These correspond to five known genes in this interval, and two genes identified by the homology of their predicted products to known proteins from other organisms.

Alleles↗
PubMed1995

White as a reporter gene to detect transcriptional silencers specifying position-specific gene expression during Drosophila melanogaster eye development.

The white+ gene was used as a reporter to detect transcriptional silencer activity in the Drosophila genome. Changes in the spatial expression pattern of white were scored in the adult eye as nonuniform patterns of pigmentation. Thirty-six independent P[lacW] transposant lines were collected. These represent 12 distinct pigmentation patterns and probably 21 loci. The spatial pigmentation pattern is due to cis-acting suppression of white+ expression, and the suppression probably depends on cell position rather than cell type. The mechanism of suppression differs from inactivation by heterochromatin. In addition, activation of lacZ in P[lacW] occurs also in specific patterns in imaginal discs and embryos in many of the lines. The expression patterns of white+ and lacZ may reflect the activity of regulatory elements belonging to an endogenous gene near each P[lacW] insertion site. We speculate that these putative POSE (position-specific expression) genes may have a role in pattern formation of the eye as well as other imaginal structures. Three of the loci identified are optomotor-blind, engrailed and invected. teashirt is also implicated as a candidate gene. We propose that this "silencer trap"' may be an efficient way of identifying genes involved in imaginal pattern formation.

ATP-Binding Cassette Transporters↗
PubMed1991

The sources of genetic variability in highly inbred long-term selected strains of Drosophila melanogaster.

A highly inbred, long-term selected for low fitness strain LA of Drosophila melanogaster possesses a significant mutational load and unusually high rates of spontaneous mutability as revealed by CyL/Pm method. Our results indicate that during cross of CyL/Pm to LA strains, destabilization of copia-like and mobile elements and induction of H-E hybrid dysgenesis take place. The role of these processes in causing considerable genetic variability of LA strain is discussed.

Animals↗
PubMed1989

Position-effect variegation and intercalary heterochromatin: a comparative study.

The behaviour of IH (intercalary heterochromatin) regions of Drosophila melanogaster polytene chromosomes was compared with that of euchromatin condensed as a result of position-effect variegation. Normally replicating regions, when subject to such an effect, were found to become among the last regions in the genome to replicate. It is shown that the factors which enhance position effect (low temperature, the removal of the Y chromosome, genetic enhancers of position effect) increase the weak point frequency in the IH, i.e. enhance DNA underreplication in these regions. We suggest that the similarity in the properties of IH, CH (centromeric heterochromatin) and the dense blocks induced by position effect is due to strong genetic inactivation and supercondensation caused by specific proteins in early development. The primary DNA structure is not likely to play a key role in this process.

Animals↗
PubMed1988

Intercalary heterochromatin in Drosophila. III. Homology between DNA sequences from the Y chromosome, bases of polytene chromosome limbs, and chromosome 4 of D. melanogaster.

Molecular and cytogenetic characteristics are given of a 2846 bp DNA sequence from the YDm12 clone, previously derived from the long arm of the Drosophila melanogaster Y chromosome. Sequence analysis revealed within it a 1176 bp fragment with 37 bp terminal inverted repeats, flanked by 6 bp direct repeats. This fragment (called "element 1360") appeared to be A-T rich, and was saturated with short direct and inverted repeats of different degrees of homology and consensus sequences for transcription, potential Z-DNA transition and autonomous replication. After in situ hybridization to polytene chromosomes, the element 1360 exhibited variable, strain-specifics location in the euchromatic parts of the chromosome arms, but constant heavy labelling of the X chromosome region 12E1-2, autosomal regions 42B1-3, 52A1-2, 62A1-2, 75B, 82C1-3, chromosome bases, the chromocentre and numerous sites of chromosome 4. The possible role of element 1360 in heterochromatin organization is discussed.

Animals↗