Vol 12, No 1 (2014)

The present review summarizes data on 5-hydroxymethylcytosine - a modification of cytosine with a recently discovered epigenetic effect. The biochemical mechanisms of 5-hydroxymethylcytosine formation and further modification in the mammalian genome are discussed; the role of 5-hydroxymethylcytosine in the epigenetic reprogramming during mammalian gametogenesis and early embryogenesis as well as in the regulation of gene expression is analyzed; data on the diseases and the adverse environmental factors, linked to the DNA hydroxymethyaltion disruptions is shown.

Background: A disbalance of pro- and anti-inflammatory cytokines can negatively affect early stages of human embryogenesis. The association between polymorphism of cytokine genes (-31С-Т IL1B, -174G-C IL6, -308G-A TNFα and -592С-A, -819C-T IL10) and a pregnancy loss was studied. Materials and method: Study was performed on DNA samples from two groups of women with pregnancy loss: those with a missed abortion (MA) (n = 62) and those with a spontaneous abortion (SA) (n = 62). The control group included 114 women with normal pregnancy. Cytokine genotyping was performed using PCR with sequence-specific primers, with the “SNP-express” kit (Lytech, Russian Federation). Results: Increase in the frequency of heterozygotes for -31С-Т polymorphism of the IL1β gene among women with MA (58.1) if compared with those with SA (36.7%) was found. In the SA group the frequency of heterozygotes for -592С-Т of the IL10 gene was higher (56.7%) than in the control group) (32.5%). The frequency of the -819Т allele of IL10 gene among women with SA was higher than in the control group (0.33 vs 0.23). The -308A allele of the TNFα gene featured the lowest frequency in the SA group if compared with those in the MA and the control group). Conclusion: Our data show that the risk of spontaneous abortion increases if -592A and -819T IL-10, and -308G TNFα genes` alleles are present in the genotype.

Background. Alfalfa root nodule bacteria (Sinorhizobium meliloti) are among the most active symbiotic N2-fixers. Their symbiotic efficiency (SE) defined as an ability to enhance the productivity of inoculated host plants is the polygenic trait controlled by a complicated system of genes, inactivation of which can result in either decrease or increase of SE. Analysis of previously identified eff-genes, whose mutations result in SE increase, revealed their location in different parts of genome (chromosome or megaplasmids) and demonstrated that these genes are not involved in operation of nitrogenase system. Mutations in these genes have pleiotropic effects, changing various cultural-biochemical properties of bacteria. Materials and methods. The object of research were the laboratory S. meliloti strain CXM1-105 and its Tn5-mutants with Eff++ phenotype, which are able to grow in diagnostic media containing indicator of cell redox potential ТТC, herbicide 2М-4ХМ or the Congo Red dye. New eff-genes were identified using the modified method of “inverted” PCR. Results. We obtained three Tn5 mutants with an increased SE in which the symbiotic phenotypes are dependent on the host. Two-factor analysis of variance demonstrated that the genotypic difference between mutants is most pronounced under the salt stress, while in its absence SE is determined mostly by the host genotype. Molecular-biological analysis revealed that the T4 mutant harbours the Tn5 insertion in the mtaD gene, T795 - in the thiC gene, and M3 - in the gene which encodes a protein belonging to the GntR family of transcription regulators. Conclusion. We demonstrated firstly that mutations in genes involved in transcription regulation, phosphonate metabolism and thiamine biosynthesis may result in a SE increase. The “inverted” PCR method enabled us to rapidly extract DNA fragments flanking the transposon, which suggests applicability of this method for identification of new rhizobia genes marked by Tn5.

Background. Heavy metals are dangerous industrial pollutants. Phytoremediation technology is a promising way to detoxificate polluted territories. Heavy metals hyperaccumulating plants present the base for development of these technologies. Many hyperaccumulators belong to the family Brassicaceae (mostly to the Alysseae tribe). Results. Analysis of molecular phylogeny and distribution of hyperaccumulation ability within the tribe Alysseae has been performed using sequences of the ITS1-5.8S rDNA-ITS2 region. Neighbor-joining tree has been reconstructed to investigate affinity within Alysseae species. For the first time molecular characters (variable region of the ITS2 structures and compensatory nucleotide substitutions availability) have been used to analyze phylogenetic structure of the tribe. Conclusion. Most of the known hyperaccumulators among species of the Alysseae tribe belong to the Odontarrhena section. ITS2 primary and secondary structure analysis results in the partition of the tribe Alysseae into five clades.