Genetika最新文献

It is known that in Azospirillum brasilense strains Sp245 and SR75 included in serogroup I, the repeat units of their O-polysaccharides consist of five residues of D-rhamnose, and in strain SR15, of four; and the heteropolymeric O-polysaccharide of A. brasilense type strain Sp7 from serogroup II contains not less than five types of repeat units. In the present work, a complex of nondegenerate primers to the genes of A. brasilense Sp245 plasmids AZOBR_p6, AZOBR_p3, and AZOBR_p2, which encode putative enzymes for the biosynthesis of core oligosaccharide and O-polysaccharide of lipopolysaccharide, capsular polysaccharides, and exopolysaccharides, was proposed. By using the designed primers, products of the expected sizes were synthesized in polymerase chain reactions on genomic DNA of A. brasilense Sp245, SR75, SR15, and Sp7 in 36, 29, 23, and 12 cases, respectively. As a result of sequencing of a number of amplicons, a high (86–99%) level of identity of the corresponding putative polysaccharide biosynthesis genes in three A. brasilense strains from serogroup I was detected. In a blotting-hybridization reaction with the biotin-labeled DNA of the A. brasilense gene AZOBR_p60122 coding for putative permease of the ABC transporter of polysaccharides, localization of the homologous gene in ~120-MDa plasmids of the bacteria A. brasilense SR15 and SR75 was revealed.

Transgenic Nicotiana tabacum L. cv. SR1 plants, characterized by an increase in the level of dsRNA-specific hydrolytic activity after induction by wounding, were obtained. The Solanum lycopersicum anionic peroxidase gene promoter (new for plant genetic engineering) was for the first time used for the induced expression of the target Serratia marcescens RNase III gene. Upon infection with the tobacco mosaic virus (TMV), the transgenic plants of the obtained lines did not differ significantly from the control group in the level of TMV capsid protein accumulation. In general, no delay in the development of the infection symptoms was observed in transgenic plants as compared with the control group. The obtained transgenic plants represent a new model for the study of the biological role of endoribonucleases from the RNase III family, including in molecular mechanisms of resistance to pathogens.

The insulin/insulin-like growth factor signaling pathway is involved in the regulation of the synthesis of insect gonadotropic hormones, juvenile (JH) and 20-hydroxyecdysone (20E). We carried out the immunohistochemical analysis of the insulin receptor (InR) expression in the corpus allatum (the JH-producing gland) and in the ovarian follicular cells (a site for the synthesis of 20E precursor, ecdysone) in the process of sexual maturation of D. melanogaster females and examined the influence of exogenous JH on the InR expression in these tissues. For the first time, it was demonstrated that InR was expressed in follicular cells and that its expression in corpus allatum and follicular cells of Drosophila females was stage-specific, i.e., the expression intensity in young females greatly exceeded that in mature individuals. We also found a negative feedback loop in the regulation of JH levels by the insulin signaling pathway in Drosophila adults: the experimental increase in the JH titers in young females dramatically reduced the InR expression intensity in corpus allatum and follicular cells.

The dependence of expression of miRNAs and their precursors (pre-miRNAs) on the DNA methylation level in HeLa cells 8 days after mitomycin C treatment was studied. A massive parallel DNA sequencing method was applied to analyze miRNA expression. 5-Azacytidine (DNA methylation inhibitor) was added to the medium 6 days after mutagenic agent exposure. The results indicated that the change in expression for some mature miRNAs (39 of 61) was accompanied by the change in the expression of their pre-miRNAs, while there were no significant changes in the expression of pre-miRNA for other mature miRNAs (22 of 61). The aberrant expression was maintained by 8 of 61 mature miRNAs and 6 of 55 pre-miRNAs in the induced HeLa cells after 5-azacytidine treatment. In addition, the expression of more than 90% of miRNAs, which indicated a significant change in expression after mitomycin C treatment, does not depend or depends slightly on the DNA methylation level in HeLa cells without mitomycin C treatment. The results suggest that mitomycin C induces aberrant DNA methylation which affects maintenance of changes in the miRNA expression in cell generations after mutagen treatment.

Stilbenes are valuable plant phytoalexins, the biosynthesis of which is characteristic of different groups of phylogenetically unrelated plants. It is believed that all the stilbenes are the derivatives of resveratrol (3,5,4'-trihydroxy-trans-stilbene) or compounds close to it (pinosylvin or piceatannol). The last stage of the resveratrol biosynthesis takes place with the involvement of stilbene synthase or resveratrol synthase (STS). The family Pinaceae is characterized by the presence of the derivatives of pinosylvin (genus Pinus) and piceatannol (genus Picea), the biosynthetic pathways of which are scarcely examined. Previously, in different species of the genus Picea, only two stilbene synthase genes were described. On the basis of RNA isolated from the needles of spruce Picea jezoensis, the full-length cDNAs of the four stilbene synthase genes, PjSTS1a, PjSTS1b, PjSTS2, and PjSTS3, were obtained. Then, using the clone frequency analysis and real-time PCR, expression of the PjSTS1a, PjSTS1b, PjSTS2, and PjSTS3 genes was examined in the needles of P. jezoensis accessions of different age and sampled in different seasons (spring, summer, autumn, winter). Among the analyzed transcripts, the PjSTS1a and PjSTS1b genes were the most frequent, indicating their higher level of expression compared to other STS genes. The highest level of PjSTS1a and PjSTS1b expression was observed in autumn, while the level of PjSTS2 and PjSTS3 expression was the highest in spring and winter. Moreover, the highest PjSTS expression was detected in the young tissues of P. jezoensis in autumn, which may indicate a higher level of stilbene biosynthesis in these tissues.

Somatic mitotic and meiotic chromosomes at the pachytene and at the metaphase I of the males of the viviparous lizard, Zootoca vivipara (Lichtenstein, 1823), from northwestern Russia, belonging to the Russian form of Z. v. vivipara, are examined. The spreading of synaptonemal complexes (SC) of their chromosomes are obtained and analyzed for the first time. Eighteen SC are observed, including SC of the Z1Z1 (pairs 5 or 6) and the Z2Z2 (pair 13) sex chromosomes. Characteristics of SC are compared with the number and the shape of bivalents and with those of the karyotype structure. In the studied Russian form of Z. v. vivipara, the length ratios of bivalents correlate with that of mitotic chromosomes (2n = 36); however, some specificity in the morphology of SC of the Z1Z1 sex chromosomes is reported in this article.

The value of chromatin diminution (CD) in different species of freshwater cyclopoid copepods can differ significantly. The biological and evolutionary roles of these differences remain unclear. To expand the knowledge on CD distribution and magnitude in this group of copepods, a quick method for its evaluation was required. This study proposes a simple approach for CD assessment in copepods using quantitative realtime PCR (qPCR). The magnitude of changes in the genome size was assessed by comparing fluorescence curves of qPCR fragments of target genes for pre- and post-diminution materials. The method was tested on four cyclopoid copepods species. In Cyclops kolensis, CD was assessed as 95.3 ± 1.2; in Acanthocyclops vernalis it was assessed at 94.6 ± 0.8%; at C. insignis, it was 82.3 ± 5.2%; and for the first time, CD was found in Megacyclops viridis at 91.1 ± 2.6%. The advantages of our approach are its rapidity, simplicity and minimal requirements of materials studied.

Nucleotide sequences of the mitochondrial DNA cytochrome b (CytB) gene fragment and the control region (D-loop) of Dolly Varden (Salvelinus malma) from the Commander Islands and the Kol River of the Kamchatka Peninsula were examined. A high level of genetic variability of island populations comparable to that of the mainland population of western Kamchatka was demonstrated. The belonging of the Commander Islands chars to the genetic lineage of northern Dolly Varden Salvelinus malma malma was confirmed.

In meiotic prophase I, chromatin fibrils attached to the lateral elements of the synaptonemal complexes (SC) form loops. SCAR DNA (synaptonemal complex associated regions of DNA) is a family of genomic DNA tightly associated with the SC and located at the chromatin loop basements. Using the hybridization technique, it was demonstrated that localization of SCAR DNA was evolutionarily conserved in the isochore compositional fractions of the three examined genomes of warm-blooded vertebrates—human, chicken, and golden hamster. The introduction of the concept of the comparative loops (CL) of DNA that form of chromatin attach to SC in the isochore compositional fractions provided the calculation of their length. An inverse proportional relationship between the length of CL DNA and the GC level in the isochore compartments of the studied warm-blooded vertebrate genomes was revealed. An exception was the GCpoorest L1 isochore family. For different compositional isochores of the human and chicken genomes, the number of genes in the CL DNA was evaluated. A model of the formation of GC-rich isochores in vertebrate genomes, according to which there was not only an increase in the GC level but also the elimination of functionally insignificant noncoding DNA regions, as well as joining of isochores decreasing in size, was suggested.

The nucleotide sequence of cryptic plasmid (designated as pBL90) detected in the cells of Brevibacterium lactofermentum DSM 1412 was determined. The length of plasmid DNA is 67826 bp. Comparison of the nucleotide sequence of pBL90 with known plasmid sequences showed no long regions of significant homology. Computer analysis of the plasmid DNA revealed 29 open reading frames (ORFs). The amino acid sequences of 15 ORFs (approximately 25% of plasmid length) have a high (>70%) level of identity to proteins from different plasmids of Corynebacterium representatives, including replicative proteins. Unusual in pBL90 is the presence of replicative genes from two different families and types of replication.