Том 53, № 4 (2017)

The role of different forms of natural selection in the evolution of genomes in root nodule bacteria (rhizobia) is analyzed for the first time. In these nitrogen-fixing symbionts of leguminous plants, two types of genome organization are revealed: (i) unitary type, where over 95% of genetic information is encoded by chromosomes (5.3–5.5 Mb in Azorhizobium, 7.0–7.8 Mb in Mesorhizobium, 7.3–10.1 Mb in Bradyrhizobium); (ii) multipartite type, where up to 50% of genetic information is allocated to plasmids or chromids which may exceed 2 Mb in size and usually control the symbiotic properties (pSyms) in fast-growing rhizobia (Rhizobium, Sinorhizobium, Neorhizobium). Emergence of fast-growing species with narrow host ranges are correlated to the extension of extrachromosomal parts of genomes, including the increase in pSyms sizes (in Sinorhizobium). An important role in this evolution is implemented by diversifying selection since the genomic diversity evolved in rhizobia owing to symbiotic interactions with highly divergent legumes. However, analysis of polymorphism in nod genes (encoding synthesis of lipo-chitooligosaccharide signaling Nod factors) suggests that the impacts of diversifying selection are restricted to the bacterial divergence for host specificity and do not influence the overall genome organization. Since the extension of rhizobia genome diversity results from the horizontal sym gene transfer occurring with low frequencies, we suggest that this extension is due to the frequency-dependent selection anchoring the rare genotypes in bacterial populations. It is implemented during the rhizobia competition for nodulation encoded by the functionally diverse cmp genes. Their location in different parts of bacterial genomes may be considered as an important factor of their adaptive diversification implemented in the host-associated microbial communities.

One of the features of transcriptional regulation in higher eukaryotes is the ability of enhancers to activate gene transcription, being at a distance, sometimes reaching several hundred kilobases away from the promoter. For several genes, it was demonstrated that cis-regulatory DNA sequences located near the core promoter sequences play an important role in the enhancer–promoter communication. In this study, we first showed that the sequence from–890 to–1620 bp relative to the yellow transcription start site, called a communicator, is required for the long-distance activation of the yellow promoter by the body and wing enhancers, as well as for their bypass of the Su(Hw)-dependent insulation. The communicator is a functional partner of a previously described regulatory element located between–69 and–100 bp in the upstream promoter region of the yellow gene. The results of this study demonstrate that specific regulatory elements in the promoter and enhancer regions may be involved in providing long-distance interactions between them.

A comparative analysis of the gene pool state in natural populations and planted stands of Norway spruce and the degree of their infestation by the bark beetle in the Moscow region was conducted taking into account the dynamic state of communities (4 populations, 148 samples, 24 isoenzyme loci). The degree of infestation by the bark beetle of conditionally native communities is 0%; for planted stands, it is 90–100%; and for a short-term community, it is 15–20%. The comparison of “healthy” populations and those infested with bark beetle by average values of observed heterozygosity (H_O) detected no significant differences. However, the test on allelic frequency heterogeneity demonstrated the difference of planted stands from conditionally native populations both by three loci (Fe-2, Idh-1, Mdh-3) and by the totality of 18 polymorphic isoenzyme loci; the short-term population differs from conditionally native population only by two loci. The value of the inbreeding coefficient by the Idh-1 locus is significantly higher in both populations infested with the bark beetle than in “healthy” populations. The results of conducted studies demonstrate the necessity of continuation of the study on the gene pool state in Norway spruce populations owing to the degree of their infestation by the bark beetle along with the study on the dynamic state of the communities; this can provide a key to solving the problem of the forest preservation from pests.

Grapevine Vitis amurensis Rupr. accumulates several valuable secondary metabolites; the most known is resveratrol—a key compound in biosynthesis of stilbenes. There is lack in the information of the regulation of the resveratrol biosynthesis in grapevin. For example, the grapevine MYB R2R3 (MYB) transcription factors (TFs) were found to modulate several branches of the flavonoid pathway. The flavonoid pathway is close to the stilbene pathway; therefore, we decided to investigate expression of the 22 MYB genes in the grape V. amurensis cell cultures and plant parts with different resveratrol content. Using real-time PCR, we showed that MYB9, 14, 15а, 60, 40, and 107 expression increased in several probes with the highest resveratrol content; therefore, probably, those genes are positive regulators of the stilbene biosynthesis. Also, we discussed the participation of the MYB transcription factors in the regulation of the stilbene biosynthesis in the grape cells.

A key issue in the study of unisexual (parthenogenetic) vertebrate species is the determination of their genetic and clonal diversity. In pursuing this aim, various markers of nuclear and mitochondrial genomes can be used. The most effective genetic markers include microsatellite DNA, characterized by high variability. The development and characterization of such markers is a necessary step in the genetic studies of parthenogenetic species. In the present study, using locus-specific PCR, for the first time, an analysis of allelic polymorphism of four microsatellite loci is performed in the populations of parthenogenetic species Darevskia armeniaca. In the studied populations, allelic variants of each locus are identified, and the nucleotide sequences of each allele are determined. It is demonstrated that allele differences are associated with the variation in the structure of microsatellite clusters and single nucleotide substitutions at fixed distances in flanking DNA regions. Structural allele variations form haplotype markers that are specific to each allele and are inherited from their parental bisexual species. It is established which of the parental alleles of each locus were inherited by the parthenogenetic species. The characteristics of the distribution and frequency of the alleles of microsatellite loci in the populations of D. armeniaca determining specific features of each population are obtained. The observed heterozygosity of the populations at the studied loci and the mutation rates in genome regions, as well as Nei’s genetic distances between the studied populations, are determined, and the phylogenetic relationships between them are established.

The one of the key pigment genes, the melanocortin 1 receptor (MC1R) gene, plays a fundamental role in the determination of coat color in a variety of mammals. However, so far there has been no report regarding the genetic variants of the MC1R promoter region and the potential association of its mutations with coat color in foxes. This work aimed to characterize 5'-flanking region of the MC1R gene and its mutations associated with coat color variations in foxes. A total of 76 individuals including 64 red foxes (Vulpes vulpes), representing 11 color morphs, and 12 arctic foxes (Vulpes lagopus), representing 2 color morphs were studied. To explore the potential cause of coat color variation in foxes, an 1105 bp region located upstream of the MC1R gene coding region was sequenced in 76 foxes. In the present study, a 1267 bp 5'-flanking region of fox MC1R gene was obtained using a PCR-mediated chromosome-walking technique and a 1105 bp segment was sequenced. A total of 8 novel SNPs and an insertion/deletion of 4 nucleotides were detected. The results of mutations analysis indicated that SNPs g.-52G>A, g.-266A>G, g.-297T>C, g.-300G>A and the insertion/deletion spaning positions g.-382~-379 were important in distinguishing V. vulpes and V. lagopus. This work, for the first time, described and confirmed the different variants existed in the 5'-flanking region of MC1R gene between red foxes and arctic foxes. These findings may be extremely helpful for further exploring the alternative splicings or promoter activity of MC1R gene for different coat-colored foxes.

The structure and diversity of mitochondrial DNA (mtDNA) macrohaplogroup U lineages in Russians from Eastern Europe are studied on the basis of analysis of variation of nucleotide sequences of complete mitochondrial genomes. In total, 132 mitochondrial genomes belonging to haplogroups U1, U2e, U3, U4, U5, U7, U8a, and K are characterized. Results of phylogeographic analysis show that the mitochondrial gene pool of Russians contains mtDNA haplotypes belonging to subhaplogroups that are characteristic only of Russians and other Eastern Slavs (13.7%), Slavs in general (11.4%), Slavs and Germans (17.4%), and Slavs, Germans, and Baltic Finns (9.8%). Results of molecular dating show that ages of mtDNA subhaplogroups to which Russian mtDNA haplotypes belong vary in a wide range, from 600 to 17000 years. However, molecular dating results for Slavic and Slavic-Germanic mtDNA subhaplogroups demonstrate that their formation mainly occurred in the Bronze and Iron Ages (1000–5000 years ago). Only some instances (for subhaplogroups U5b1a1 and U5b1e1a) are characterized by a good agreement between molecular dating results and the chronology of Slavic ethnic history based on historical and archaeological data.

Phylogenetic relationships of the nine Lake Baikal endemic caddisfly species with the representatives of the genus Apatania (Apataniidae) were reconstructed on the basis on nucleotide sequences of the mitochondrial COI gene. The results of Bayesian analysis pointed to the relationships of the endemics with the North American Apatania incerta (Banks, 1897) and A. sorex (Ross, 1941). The divergence of the genetic lineages of the Baikalian and Nearctic apataniids occurred in the Late Oligocene–Early Miocene. On the dendrogram, endemic species formed two monophyletic clades corresponding to the tribes Thamastini and Baicalinini. It was also found that the genus Protobaicalina was polyphyletic, while the genus Baicalina was a species flock. Our analysis showed that the nearest common ancestor of the studied Baikal caddisfly species existed about 21 Mya, while the modern species composition of endemic fauna dates back to Pliocene–Pleistocene age (2.5–0.7 million years).