Vol 59, No 12 (2023)

Nonsuicidal self-injury (NSSI), or self-harm is widely spread, especially among the young people. However, despite the problem’s relevance, NSSI was investigated mainly from the psychological and social perspective, while a fairly small number of biological studies of NSSI have been published to date. The aim of this narrative review was to analyze all the currently available publications on the genetics and epigenetics of NSSI – one of the most promising areas in biological research. We discussed and analyzed all stages of genetic research of NSSI: from twin studies and studies of self-harm in the framework of hereditary diseases to candidate genes, genome-wide, epigenetic and gene-environment interactions studies. We demonstrated data indicating significant contribution of genetic and epigenetic factors to the development of NSSI, discussed advantages and limitations of analyzed studies, outlined prospects for further research in this area.

Drosophila melanogaster is a common genetic object for research of RNA-interference pathways and mobile elements regulation. Nowadays taking a part in control of retrotransposon expression the system of piRNA-interfecence well studied in ovary tissues. It is strongly believed that D. melanogaster piRNA-interference is used for retrotransposon suppression only in gonads, and two distinct pathways of piRNA biogenesis exist. Both mechanisms use transcripts of piRNA-clusters (accumulations of truncated and defect mobile elements copies): from unstrand clusters in the first case and from dualstrand clusters in the second, transcribed with one or both DNA chains correspondingly. It is well-known that proper dualstrand clusters function depends on the gene rhino, while unistrand clusters are transcribed rhino-independent and transcripts are spliced. In this paper we show that rhino participates in unistrand flamenco transcripts splicing and the piRNA-interference significance for regulation of several retrotransposons not only in gonads, but in other organs.

Antimicrobial peptides (AMPs) are major components of innate immunity in plants and animals. AMP genes have significant intra- and interspecific polymorphism, the role of which is poorly understood. Previously, by high throughput transcriptome sequencing of wheat plants, we identified defensin genes up-regulated upon infection with the pathogenic fungus Fusarium oxysporum and/or treatment with resistance inducers. In the present work, a bioinformatic search in NCBI databases for peptide homologues of these defensins was carried out using the sequences of their γ-cores, the sites of the molecules responsible for antimicrobial activity. DEFL1-16 homologues were identified in 95 species of angiosperms belonging to 48 families and 30 orders of monocotyledonous and dicotyledonous plants. The ubiquitous distribution of this defensin in angiosperms suggests its involvement not only in defense, but also in other processes in flowering plants. Homologues of other defensins induced by infection were found only in plants of the Poaceae family, which suggests the existence of a Poaceae-specific defense mechanism associated with the expression of these defensins. Among the γ-core variants of wild plant defensins identified in the study, the peptides with better antimicrobial activity compared to wheat, might be present, which are of considerable interest for the development of new antibiotics for medicine and agriculture.

Population genetic structure in polar bear (Ursus maritimus) from model areas in the Russian Arctic is considered based on materials collected in the period 2010–2021. Data on polymorphism of 17 microsatellite loci of nuclear DNA and a 610 nucleotide long mtDNA D-loop fragment were obtained for 93 animals. For the studied sample of adult polar bears, a high genetic diversity of nuclear DNA and a low value of nucleotide variability π for mitochondrial DNA were found. For all genetic markers, differentiation of bears from the southern part of the Barents Sea from animals from the north of the Barents and Kara seas was found. These groups differ in the distribution of the mitochondrial marker (θ_st = 0.270) and are weakly differentiated by nuclear loci (R_st = 0.018).

Miscarriage is potentially associated with abnormal epigenetic regulation of genes responsible for the development of the embryo and placenta. The aim of this work was to analyze the methylation level of various subfamilies of the LINE-1 retrotransposon, which makes up about 17% of the entire genome, in chorionic villi of spontaneous abortions of the first trimester of pregnancy with different karyotypes, including the most common aneuploidies. The methylation profile in the LINE-1 retrotransposon promoter was analyzed using targeted bisulfite massive parallel sequencing in chorionic villi of induced abortions (n = 39), spontaneous abortions with normal karyotype (n = 173), trisomy 16 (n = 62) and monosomy X (n = 46), and peripheral blood lymphocytes of healthy volunteers (n = 17). The level of methylation of the LINE-1 retrotransposon subfamilies in the control groups of adult lymphocytes and chorionic villi of induced abortions was the highest for evolutionarily young L1HS subfamilies, lower for the more ancient L1PA2 and L1PA3 subfamilies, and the lowest for the even more ancient L1PA4 subfamily. In the groups of spontaneous abortions, an increased level of LINE-1 methylation was observed, and this effect was more pronounced for the older LINE-1 subfamilies. The revealed patterns indicate less control over the older subfamilies of the LINE-1 retrotransposon in the human genome, which can potentially be used as regulatory elements for nearby genes involved in embryonic development. An increase in the level of methylation of such sequences can disrupt the development of the placenta and embryo and make a certain contribution to miscarriage.

The hierarchical structure of metapopulations characteristic of humans with their subdivision into parts (subpopulations), usually classified on the basis of administrative-territorial division, principles of biological systematics, etc., is considered. Attention is focused on the description of surname divergence of subpopulations. The surname inbreeding coefficient Fs is expressed through the divergence indices, which is similar to the traditional inbreeding coefficient in population genetics. Its expansion by hierarchy levels into the sum of increments of the surname inbreeding coefficient corresponding to separate levels is obtained. The relationship between the found decomposition and the decomposition of the dispersion of the distribution of the surname concentration by subpopulations is demonstrated. With an additional assumption about the independence of the concentration of the surname and Fs, the factorization of Fs by hierarchy levels is found in line with the ideas of S. Wright. It is simplified with a small surname divergence of subpopulations when the Fs coefficient of the entire metapopulation is equal to the sum of the average Fs values at individual levels of the hierarchy. The underestimation of surname inbreeding was obtained, when subpopulations of a higher rank serve as units of observation instead of undivided subpopulations of the first level of the hierarchy. These results are statistical characteristics of the hierarchical structure, and not a feature of a particular population system, and do not follow from one or another model of microevolution. They are computationally independent of the hierarchical system under study, but allow characterizing their heterogeneity quantitatively. The results obtained refer to rural and urban hierarchical metapopulations as separate components of the entire population. In an appendix that can be read independently, genetic analogues of the properties found are given without proof in respect to the genetic structure of a metapopulation.

The polytypic species of nodule bacteria Rhizobium leguminosarum (includes biovars viciae and trifolii) and Neorhizobium galegae (biovars orientalis and officinalis) differ in the nucleotide polymorphism of housekeeping genes (hkg) and of symbiotically specialized genes (sym) that control the formation of N₂-fixing nodules in leguminous plants. In R. leguminosarum, p-distance values for sym genes are higher than for hkg genes in strains from the same and from different biovars. In N. galegae, differences between biovars in sym genes are higher than in hkg genes while within biovars, polymorphism in sym genes is lower than in hkg genes. Coefficients of biovar differentiation for both groups of genes are higher in N. galegae than in R. leguminosarum, possibly reflecting the spatial isolation of N. galegae biovars. In these species of rhizobia, the phylogenetic congruence of sym and hkg genes is more pronounced in N. galegae than in R. leguminosarum. This difference indicates an active transfer of sym genes in R. leguminosarum populations possibly representing an important factor of the deep diversification for symbiotic traits in this rhizobia species.