[Influence of hairpin RNA, specific to the gene lawc, on expression of overlapping genes of the lawc/Trf2 complex in D. melanogaster].

We used a genetic system of the gene complex leg-arista-wing complex/TBP related factor 2 (lawc/Trf2) as a suitable model for in vivo study of operational characteristics of divergent overlapping genes. We established lines of transgenic fruit flies carrying constructs capable of expressing hairpin RNA directed at post-transcriptional suppression of the mRNA gene lawc by way of RNA-interference. The attempt to artificially suppress lawc-transcripts caused a rise in the level of expression of the gene lawc by several times. It is shown that change in the concentration of lawc-transcripts can affect the concentration of Trf2 transcripts. Possible mechanisms of regulation of expression of the overlapping genes studied are discussed.

[Recovery of genomic regions affecting lawc/Trf2 expression during Drosophila melanogaster development].

Leg-arista-wing complex (lawc) mutations affect the expression of D. melanogaster proteins homologous to a human basic transcription factor, TBP (TATA-box binding protein) Related Factor 2 (TRF2), specifically involved in development. The paper for the first time reports the application of genetic screens for various genomic regions to recover genetic interactions between the lawc/Trf2 gene and other genes and genetic loci by using Deficiency Kit lines with small deletions in total providing maximal coverage of the genome. The deletion mapping allowed us to recover 26 genomic regions that, when deleted, are lethal or modify the mutant phenotype due to a decreased TRF2 expression level. These deletions could be useful in identifying both novel TRF2 targets and its positive and negative regulators. There is evidence that TRF2 can be a component of high molecular DNA Replication-related Element Factor (DREF)- and Nucleosome Remodeling Factor (NURF)-containing complexes. The present study for the first time reports new genetic interactions of lawc/Trf2 with genes that encode basic and specific transcription factors. In most cases, if mutated, those genes caused developmental defects or death of progeny. However, in the case of the e(y) 1 gene, coding for the Taf9 transcription factor, only the male reproductive system is impaired when the lawc/Trf2 phenotype is associated with a e(y)l gene mutation. Mutant lawc(p1)e(y)1(u1) males become infertile due to primary spermatocyte maturation arrest and impaired premeiotic chromosome condensation in germ cells.

[Gene expression modulation is an evolutionary resource of adaptive alterations in the morphogenesis of insect limbs].

Hypomorphic mutations have been investigated of the genes spineless (ss), Distal-less (Dll), leg-arista-wing complex/TBP-related factor 2(lawc/Trf2), CG5017, and hsp 70 in order to explore the effects of their expression level on the formation of distal structures of antenna and legs of Drosophila melanogaster. We demonstrated the effect of the CG5017, hsp 70, Dll, and lawc gene transcription level on phenotypic manifestation of the ss gene mutation and the involvement of these genes into morphogenesis regulation of Drosophila melanogaster limbs. The total decrease in the level of the CG5017, hsp 70, Dll, and laws gene expression level was shown to promote a loss of the segmented pattern of distal structures of legs and antennae and a reversion of Drosophila limb morphogenesis to the evolutionarily earlier progenitors of insects. A hypothesis is proposed considering limb morphogenesis of insects as an evolutionary ancient process of formation of amorphous-crystal chitin structures with catalytically modifying participation of gene expression products.

[Interaction of the ss and CG5017 genes in the regulation of morphogensis of limbs in Drosophila melanogaster].

The influence of the P-element built into the area of the CG5017 gene on the mutation of the spineless (ss) gene was studied. It was shown that the insertion of the P-element decreased the level of transcription of CG5017 approximately twofold. Modulation of the level of transcription of the CG5017 gene helped demonstrate, for the first time, its influence on the phenotypic manifestation of the mutation of the ss gene, which shows their interaction in the process of regulation of morphogenesis of limbs in Drosophila melanogaster.

[Source of asymmetry in ontogeny: early polarization of the germline cyst and oocyte in Drosophila].

One or more body axes are already formed in the egg in many vertebrates and invertebrates. In Drosophila, the anteroposterior and dorsoventral axes are determined during oogenesis owing to the asymmetric localization of the bicoid, oskar, and gurken mRNAs in the oocyte (prospective egg). The localization of these transcripts depends on the polarized organization of the oocyte cytoskeleton and, consequently, the oocyte polarity. Initial asymmetry, leading to the oocyte polarity, is established in early ontogeny, during oocyte determination. The review considers the steps of early polarization and oocyte differentiation in Drosophila, the genetic control of these processes, and the findings that suggest an early oocyte polarity for vertebrates.