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O B Simonova

Publications and source records attributed to O B Simonova.

At least 19 recordsLinked to original sources
PubMed2005

[Overexpression of a novel gene toothrin in Drosophila].

A newly found locus of the Drosophila melanogaster genome, named toothrin (tth) has been used to study the role of the conserved domain 2/3 of genes from the d4 family. In contrast to the 2/3 domain of all vertebrates studied (including humans), which is always accompanied by the d4 domain, the tth gene contains the sequence encoding the 2/3 domain but lacks that encoding the d4 domain. The tth gene overexpression has been studied using the two-component system UAS-GAL4. It has been demonstrated that the tth overexpression at the third-instar larval (prepupal) stage decreases survival rate, simultaneously causing a substantial deceleration of development in Drosophila. It is known that the change of developmental stages in Drosophila is controlled by the rates of the expression of ecdysteroid and juvenile hormones (JHs). It is supposed that the overexpression of the tth gene causes either a shift in the ecdysterone-to-JH ratio (through a decreased JH decay rate or a delayed initiation of ecdysone synthesis) or a deceleration of the release of ecdysterones synthesized.

Animals↗
PubMed2003

[Use of a genetic system of the chimeric protein P-Ph in the repression of gene transcription of the leg-arista-wing complex in Drosophila].

Preliminary analysis of the leg-arista-wing complex (lawc) gene region in the corresponding mutants revealed P element insertion in the transcribed region of this locus. To demonstrate the main role of P element insertion in the complex pleiotropic phenotypic manifestation of the lawc gene, a system using P-Ph chimeric protein and based on the P-mediated repression of the lawc in vivo transcription was applied. As a result, extreme lawc-mutant phenotypes were obtained and examined. The P-Ph-mediated decrease of the level of the lawc gene transcription was also demonstrated.

Alleles↗
PubMed2001

Cerd4, third member of the d4 gene family: expression and organization of genomic locus.

Two members of the d4 family of presumptive transcription modulators, neuro-d4 (Neud4) and ubi-d4/Requiem (Req), have been characterized previously. We cloned and characterized the third member of this gene family, cer-d4 (Cerd4), from chicken and mouse cDNA libraries. The expression patterns of Cerd4 gene in both species are similar and more restricted than expression patterns of other two d4 genes. The main sites of Cerd4 expression are retina and cerebellum, where multiple transcripts could be detected. Two major types of Cerd4 proteins are a full-length isoform possessing all domains characteristic to the d4 family and truncated XZ isoform without C-terminal tandem of PHD fingers. The developmental kinetics of expression of these isoforms is different. The intron/exon structure of human Cerd4 gene is similar to that of neuro-d4 and ubi-d4/Requiem genes, but most introns of Cerd4 gene are much larger than the corresponding introns of the other two genes.

Amino Acid Sequence↗
PubMed2000

hobo-induced rearrangements are responsible for mutation bursts at the yellow locus in a natural population of Drosophila melanogaster.

In 1981 recurrent local bursts of mutability of the yellow gene were observed in a natural population of Drosophila melanogaster from Uman' (Ukraine). A series of y2-like mutations in the yellow gene were recovered during the period 1982 to 1991. Most of the mutants display the y2-phenotype, i.e. mutant yellow color of wings and body cuticle. Ninety-nine y2 mutants were shown to be generated by an inversion that occurred between two hobo elements, one located 129 bp from the start site of yellow transcription, and the other in the distal telomere region. The y2 phenotype was caused by the separation of the body and wing enhancers from the transcription unit. Many of the y2-like alleles were highly unstable and reverted to y+, which again, gave rise to y2-like mutants. We found that the y2-->y+-->y2 transitions were generated by repeated inversions between the two hobo elements mentioned. The y2 and y+ alleles lost their instability after deletion of the hobo element present at the tip of the X chromosome.

Alleles↗
PubMed2000

[Genomic organization of the murine neuro-d4 gene].

As the first step toward obtaining the null mutation or knock out of the neuro-d4 gene, we isolated phages containing fragments of the gene from a mouse genomic library. The nucleotide sequence of a region of the gene more than 10 kb in size was determined.

Amino Acid Sequence↗
PubMed2000

[Taste sensitivity in homeotic mutants of the drosophila leg-arista-wing complex].

It is well established that taste chemoreceptors in Drosophila are located on the tarsi of the first leg pair. In order to investigate the influence of the novel homeotic arista-tarsus transformation on behavior, an analysis of taste perception in the lawc-mutants, characterized by the transformation of the arista into tarsus elements, was carried out. The data were subjected to thorough statistical treatment. It was shown that elements of an additional leg that appeared as a result of homeotic transformation of the arista were sensitive to gustatory stimuli. Analysis of the innervation of the homeotic organs by means of cobalt staining of afferent projections showed that the afferents starting from the homeotic leg reached the thoracic ganglion.

Animals↗
PubMed2000

[A novel trans-regulatory locus in Drosophila].

A new trans-regulatory gene, leg-arista-wing complex (lawc), was earlier identified in a system of prolonged genetic instability induced by transpositions of structurally different mobile genetic elements, the P element and MDG Stalker. Mutations of this gene alter expression of many loci, including the achaete and scute proneural genes and the cut locus coding for a homeobox-containing protein. A product of lawc is involved in regulating expression of white. This role is played in cooperation with the product of Zeste which provides for a contact between the white promoter and enhancer. A possible role of the new locus in organogenesis, neurogenesis, and embryonic development is discussed on the basis of experimental findings.

ATP-Binding Cassette Transporters↗
PubMed2000

[Study of the olfactory response in the Drosophila homeotic mutant leg-aristae-wing complex gene].

Antennae are known to be olfactory organs in Drosophila. The leg-aristae-wing complex (lawc) mutation causes a homeotic transformation of the arista (the fifth element of antenna) into tarsal elements. To test how the homeotic transformation of the arista into the tarsus can affect behavior, we studied the olfactory response in the lawc mutants. The data were carefully processed by statistical methods. In spite of a low penetrance of the trait of arista transformation, the mutant flies were found to be approximately half as perceptible to attractant odors than the wild-type flies.

Animals↗
PubMed1998

[Role of the lawc(p1) mutation in the regulation of the white locus expression in Drosophila].

The lawcp1 mutation of the leg-arista-wing complex (lawc) gene alters expression of three proneural loci: achaete, scute, and cut. In combination with the product of the zeste (z) gene, the product of the lawc gene regulates expression of the white (w) gene. The -w B3 mutation was genetically analyzed in compounds with various z and w mutations and dominant mutations modifying the z-w interaction. The results showed that lawcp1 can enhance the transvection effect. The lawc gene was assumed to regulate expression of the white locus at the level of chromatin condensation.

Animals↗
PubMed1996

[Differential characteristics of the temperature-sensitive period of the lawcp1 mutation on the basis of macrochaetae overexpression in Drosophila].

Temperature-sensitive periods (TSPs) of lawcpl mutations were studied via the frequencies of arising of extras macrochaetae for each macrochaetae type separately. TSPs for the formation of extras macrochaetae of original classes were unevenly distributed within larval instars II and III. It was found that macrochaetae of different types differed from one another in their temperature sensitivity. The TSP of development of macrochaetae belonging to new ectopic classes was multiphase, with the first phase at larval instar II, and the second phase, at the prepupal to early pupal stage. It is assumed that in Drosophila, the products of the lawc gene participate, along with other genes, in the development of the nervous system through regulation of ac-sc expression, both in proneural clusters and outside them.

Alleles↗
PubMed1996

[Genetic analysis of the lawc(p1) mutation in combination with different alleles of AS-C genes in Drosophila].

Phenotypic expression of mutations within the leg-aristal-wing complex (lawc) locus involves alteration of the number and location of macrochaetae. In Drosophila, development of macrochaetae depends on products of the two proneural genes, achaete (ac) and scute (sc), constituents of the approximately 90-kb ac-sc gene complex (AS-C). Untranscribed regions of AS-C involve enhancer-like cis-elements that are responsible for the local combination of some factors specifically determining expression of the ac-sc genes in larval imaginal discs of Drosophila. In the present work, the frequency of appearance of additional macrochaetae was tested to analyze phenotypic exhibition of the temperature-sensitive lawcp1 allele. This mutation was also genetically analyzed in combination with various AS-C alleles involving alterations of transcribed or cis-regulatory regions of this gene complex. A hypothesis that the lawc gene encodes a factor determining the specific expression of the ac-sc genes is discussed.

Alleles↗
PubMed1995

[Determination of a temperature-sensitive period of the new mutation lawc(P1) in Drosophila melanogaster].

Determination of the period of temperature sensitivity in the temperature-sensitive allele of the regulatory lawc(P1) mutation was performed. Homeotic transformation of arista into tarsus, frequency of leg deformation, and bristle superexpression were examined. The sensitive periods were detected using reciprocal changes of cultivation temperature from 28 to 17 degrees C and from 17 to 28 degrees C. The temperature-sensitive period (TSP) for arista transformation was shown to manifest polyphasic expression and sexual dimorphism. In females, it occurred in late third instar larvae (the first phase) and prepupae (the second stage); in males, it includes the whole period from the late third instar larva upto and including prepupa. TSP for the frequency of deformed legs was polyphasic and took place during the third larval instar (the first phase) and prepupa stage (the second one). TSP for bristle superexpression occurred during a single interval from the late third larval instar until the early prepupa stage. The products of the lawc gene are assumed to play a role both in the cell proliferation in the legs of antennal and imaginal discs and in the control of bristle expression at the final stages of Drosophila ontogeny.

Alleles↗
PubMed1992

Intragenic suppression: Stalker, a retrovirus-like transposable element, can compensate for a deficiency at the cut locus of Drosophila melanogaster.

A number of mutations at the cut locus were induced by non-precise excision of a silent P-element insertion which resulted in deletions at the regulatory region of the locus. Unexpectedly, a reversion of one of these mutations was found, which appears as a result of insertion of Stalker (a retrovirus-like mobile element) near the 1.3 kb deletion. Thus an insertion of a retrovirus-like mobile element can suppress the deficiency at the regulatory region of a gene.

Animals↗
PubMed1992

[Participation of mobile element hobo in transposition events in the long-term instability system of Drosophila melanogaster].

The lines with an active hobo elements as well as those without any hobo fragments were hybridized with the y2sc1waG line. This resulted in the appearance of a number of mutations at the white, miniature, and some other loci. The authors analysed, in which way the hobo transposable elements take part in mutagenesis in these crosses. Most of the white mutants obtained were analysed and transpositions of hobo and Stalker elements were demonstrated. Both independent and simultaneous transpositions were found. It was shown by means of the Southern blot analysis that additional hobo or Stalker insertion into or close to the parental unknown waG insertion resulted in mutant white phenotype's shift toward both extreme and partial reversion. Possible participation in mutagenesis of other mobile elements is also under debate.

Animals↗
PubMed1990

A novel transposition system in Drosophila melanogaster depending on the Stalker mobile genetic element.

Crosses between the Drosophila melanogaster y2sc1waG strain or some of its derivatives and the FM4 strain yielded insertional mutagenesis with a frequency of 10(-3)-10(-4). The system differs in several respects from the known cases of hybrid dysgenesis: (i) it does not depend on the direction of a cross; (ii) destabilization continues for a long time after initial crosses; (iii) mutations may occur at different stages of development. The mutation in the yellow locus has been cloned and found to depend on insertion into the coding region of the gene of a novel mobile genetic element designated as Stalker. The sequencing of Stalker termini reveals 405 bp direct repeats (LTRs) and a target 3 bp duplication, as well as some other sequences typical of retrovirus-like retrotransposons. The number of Stalker copies per genome and chromosomal localization vary among D. melanogaster strains. Before crosses, the location of Stalker on chromosomes is fairly stable in a particular strain but thereafter numerous changes in Stalker distribution take place. Most novel substrains are internally heterogenous which is indicative of the continuing Stalker transposition. Other mobile elements tested do not move. Possibly, only Stalker is mobilized in the system. Many known and novel mutations have been obtained. Comparison of their genetic localization with Stalker distribution suggests that the majority of them have been induced by the Stalker insertion.

Animals↗
PubMed1990

[Superunstable systems in Drosophila melanogaster. Analysis of mutations in signed and cut loci].

The lines of the M'-cytotype characterized by a long-term instability (which was shown to be conditioned by transpositions of the new mobile element, Stalker) were hybridized with the P-line. This resulted in the appearance of a number of superunstable mutations at the yellow, white, singed, ocelliless and some other loci. The authors analyzed four independently obtained families of superunstable mutations at the singed locus. A wide spectrum of derivatives and high frequency of mutations were demonstrated, as well as the regularities of allelic transitions. Besides this, mutagenesis at the cut locus was observed in the chromosomes carrying sn mutations with frequency of 5.05 x 10(4). By means of the blot analysis it has been shown that most of ct mutations are intragenic deficiencies, ranging from 1.3 to 3 Kb, whose appearance is, conceivably, attributed to the inaccuracy of the insertion excision (the insertion is present but fails to alter the phenotype) at the cut locus of the chromosomes with the superunstable sn-alleles. In the lines with the sn- and ct-mutations the transpositions of the P-element and the Stalker were found, which indicates their involvement in mutagenesis. The authors discuss possible effects of inserting the complicated constructions, based on the combinations of P-element and the Stalker, on the induction of superinstability.

Alleles↗
PubMed1989

Mobile genetic elements in Drosophila melanogaster (recent experiments).

Recent data obtained in the authors' laboratories concerning the behaviour of mobile genetic elements of Drosophila melanogaster are reviewed. It was found that the mobile element jockey represents the typical LINE element. It is efficiently transcribed in D. melanogaster cells in flies and in culture. Transcription is initiated from the +1 nucleotide of jockey and depends on an internal promoter. This is the first case of an internal promoter being used by RNA polymerase II. Several events which take place during the transposition bursts in ctMR2 family of strains were described. Among them are the removal of mobile dispersed genetics (mdg) elements (with solo long terminal repeat (LTR) remaining at the site of excision), complete removal of an mdg element, and reinsertion of the same mdg to the same place either in the presence or in absence of solo LTR sequence. Finally, the formation of deletions was observed. A 462-bp deletion destroying the white locus can be further repaired (w+ reversion). Thus, transposition bursts include many different genetic events. A novel system of prolonged genome destabilization was described. It depends on mobilization of a new mobile element called Stalker. After certain crosses Stalker actively moves for dozens of generations giving rise to large numbers of insertion mutations. Several novel genes were detected using mobilized Stalker. They include a modifier of mdg4 and six enhancers of yellow mutations.

Animals↗