Vol 53, No 2 (2017)

Combinatorial expression of the genes in multicellular organisms leads to the development of different cell types. The important epigenetic regulators of higher eukaryotes are the Polycomb group (PcG) and Trithorax group (TrxG) proteins. These factors control the transcription of a large number of genes involved in various cellular processes. Dysregulation of PcG and TrxG systems leads to developmental abnormalities and cancer. This review focuses on the main characteristics and properties of the Drosophila PRE elements. Furthermore, we summarize the information on the protein components of the PcG and TrxG groups and their functional activities and discuss the main aspects of competition between the proteins of these classes as well as their possible mechanisms of action.

The objective of this study was to identify transcriptional coactivators participating in transcription elongation of the hsp70 gene induced by heat shock. We found that all investigated coactivator complexes participate in transcription of this gene, as significant level of them were present at the gene promoter in its active state. For most of the coactivators (except for p300/CBP, Set2, and Mediator complex), we also observed a considerable increase of their binding level at the coding region of the gene after activation of its transcription by heat shock. We assume that coactivators CHD1, ISWI, Brm, Kismet-L, INO80, Mi-2, Gcn5, Lid/KDM5, Set1, DART1, DART4, SSRP1, PAF1, and Fs(1)h/Brd4 bind to the promoter of the active hsp70 gene and migrate to its coding region together with elongating RNA polymerase II. It can be suggested that some of these coactivators play an important role in stimulating the transition of the RNA polymerase II complex from transcription initiation to elongation stage.

The effects of histone-like protein H-NS on transcription of promoters of the Quorum Sensing regulated operons from marine luminescent mesophilic bacterium Aliivibrio fischeri and psychrophilic Aliivibrio logei, as well as from pathogenic Pseudomonas aeruginosa, are studied. In the present work, the plasmids carrying DNA fragments with the promoters Pr1f (upstream of the luxICDABEG operon from A. fischeri), P_r1l (upstream of the luxCDABEG operon from A. logei), P_r2l (upstream of luxI gene from A. logei), P_luxCf (upstream of luxC gene from A. fischeri), and P_lasI (upstream of lasI gene from P. aerugenosa) are used. In these plasmids, promoter-operator regions are transcriptionally fused to the reporter genes cassette luxCDABE from Photorhabdus luminescens. Here we have shown that the transcription of the QS-regulated promoters in E. coli hns::kan cells increases 100 to 1000 times. Furthermore, transcription of the QS-regulated promoters in E. coli hns⁺ cells increases 10 to 100 times in the cells transformed with the plasmid carrying gene ardA ColIb-P9 encoding DNA mimic antirestriction protein ArdA, inhibitor of the type I restriction-modification systems.

Region ITS1–5.8S rDNA–ITS2 is sequenced in 27 varieties of cultivated ornamental peonies, ten of which presumably originate from Paeonia lactiflora, one from P. officinalis, 13 from hybridization of P. lactiflora and P. peregrina, or P. officinalis, and three are Itoh hybrids. Comparative analysis of distribution patterns of polymorphic sites (PS) for the obtained DNA sequences and data from GenBank is carried out. Hypotheses of origin of the studied varieties, except for two, which, as previously assumed, originate from hybridization of P. lactiflora and P. peregrina, are confirmed. It is shown that the sequence ITS1–5.8S rDNA–ITS2 is a good genetic marker for cultivars of the P. lactiflora group and Itoh hybrids, and that the PS distribution patterns in these sequences can provide valuable information on the kinship and origin of individual varieties. However, insufficient knowledge of wild species from the P. officinalis kinship group limits the use of this marker in the study of varieties obtained through interspecific hybridization within the Paeonia section.

Comparison of coding nucleotide sequences of the paralogous GH1 and GH2 genes, as well as of the growth hormone amino acid sequences, in the species of closely related salmonid genera Salvelinus, Oncorhynchus, and Salmo was performed. It was demonstrated that, in different groups of salmonids, the amino acid substitution rates were considerably different. In some cases, an obvious discrepancy between the divergence of growth hormone genes and phylogenetic schemes based on other methods and approaches was revealed. These findings suggest that the reason may be multidirectional selection at duplicated genes at different stages of evolution.

We study 117 Pacific walrus samples from three rookeries within the western part of Chukchi Sea (Cape Vankarem, Cape Serdtse-Kamen, and Kolyuchin Island). We analyze the variability of nuclear (20 microsatellite loci) and mitochondrial DNA (three fragments). Two microsatellite loci which are described as microsatellites for the first time are used in this study: repeated sequences within introns of Coro1c and Plod2 genes. A high degree of genetic diversity is demonstrated for both nuclear and mitochondrial markers compared to Atlantic walrus. A high degree of genetic diversity is preserved within populations of Pacific walrus, despite a strong decline in the recent past. We discover the absence of significant differentiation for microsatellite loci and the presence of weak differentiation for mtDNA (mainly for a D-loop fragment). Walrus specimens that use the rookeries of the western part of Chukchi Sea are thought to belong to a single reproductive group.

On the basis of inter-simple sequence repeat (ISSR) loci and the nucleotide sequences of nuclear (18S and ITS-1) and mitochondrial genes (COI and 16S), a phylogenetic analysis of the three species of terrestrial mollusks of the family Bradybaenidae (Mollusca, Pulmonata), Bradybaena fruticum Müll., Bradybaena schrencki Midd., and Bradybaena transbaicalia Shileyko, was conducted to clarify their taxonomic status. The analysis showed that Br. fruticum was far apart from the other two species (Br. schrencki and Br. transbaicalia). The genetic distance between the latter puts in doubt their status as distinct species. It is suggested that the species Br. transbaicalia can be treated as a form of Br. schrencki var. transbaicalia.

For the Republic of Belarus, development of a forensic reference database on the basis of 18 autosomal microsatellites (STR) using a population dataset (N = 1040), “familial” genotypic dataset (N = 2550) obtained from expertise performance of paternity testing, and a dataset of genotypes from a criminal registration database (N = 8756) is described. Population samples studied consist of 80% ethnic Belarusians and 20% individuals of other nationality or of mixed origin (by questionnaire data). Genotypes of 12346 inhabitants of the Republic of Belarus from 118 regional samples studied by 18 autosomal microsatellites are included in the sample: 16 tetranucleotide STR (D2S1338, TPOX, D3S1358, CSF1PO, D5S818, D8S1179, D7S820, THO1, vWA, D13S317, D16S539, D18S51, D19S433, D21S11, F13B, and FGA) and two pentanucleotide STR (Penta D and Penta E). The samples studied are in Hardy–Weinberg equilibrium according to distribution of genotypes by 18 STR. Significant differences were not detected between discrete populations or between samples from various historical ethnographic regions of the Republic of Belarus (Western and Eastern Polesie, Podneprovye, Ponemanye, Poozerye, and Center), which indicates the absence of prominent genetic differentiation. Statistically significant differences between the studied genotypic datasets also were not detected, which made it possible to combine the datasets and consider the total sample as a unified forensic reference database for 18 “criminalistic” STR loci. Differences between reference database of the Republic of Belarus and Russians and Ukrainians by the distribution of the range of autosomal STR also were not detected, corresponding to a close genetic relationship of the three Eastern Slavic nations mediated by common origin and intense mutual migrations. Significant differences by separate STR loci between the reference database of Republic of Belarus and populations of Southern and Western Slavs were observed. The necessity of using original reference database for support of forensic expertise practice in the Republic of Belarus was demonstrated.