Vol 518, No 1 (2024)

PCID2 protein is a component of the eukaryotic TREX-2 complex responsible for mRNA export from the nucleus to the cytoplasm. Previously, we showed that PCID2 of D. melanogaster is involved in specific mRNA recognition and identified key amino acids responsible for interaction with the RNA of the ras2 gene. In this work, we show that point mutations of these amino acids disrupt the interaction of the protein with cellular RNA and the export of polyA-containing mRNA from the nucleus to the cytoplasm in Drosophila cells.

The article describes the first find of a bird from the Paleogene of Siberia. A tibiotarsus fragment from the Eocene Tavda Formation of the Tyumen Region (Western Siberia) is referred to Procellariiformes. The described bird is morphologically closer to Procellariidae, but comparable in size to albatrosses (Diomedeidae) and, apparently, represents the stem representatives of this family. The find indicates for the first time that either stem albatrosses or large Procellariiformes similar to them could have had a worldwide distribution already in the Eocene.

The new site of Tip-Tugai Cave (52°59’28.6”N, 57°00’22.3”E) is described. The bone-bearing layer is dated at MIS 3 isotope stage based in the fauna of small mammals. Finds of abundant remains of Crocuta spelaea individuals of different ages and the presence of large herbivores bones with hyena gnaw marks indicate that the Tip-Tugai Cave was used as a hyena den in the Late Pleistocene. This is the first described cave hyena den in the Urals.

In humans mutations in the LEPR gene, encoding leptin hormone receptor, are associated with the development of morbid obesity, lipid metabolism dysregulation, defects of fertility. In rodents spontaneous mutations in Lepr gene have been described. Lepr knock-out (KO) animals have been generated using classical KO technology or CRISPR/Cas9 system. In rodents lipid metabolism is significantly different from that in humans or rabbits, therefore rabbits are considered as the most relevant model of morbid obesity and lipid metabolism dysregulation in humans, but so far LEPR knock-out rabbits have not been reported. Here using CRISPR/Cas9 system we generated LEPR knock-out rabbit by introducing a deletion of the region around exon 10 of the LEPR gene. We showed that the body weight of the knock-out rabbit was significantly higher than an average body weight of the wild type rabbits. CRISPR/Cas9-mediated technology for the generation of the LEPR knock-out rabbits will allow for the development of the model of morbid obesity and endocrine defects in humans due to leptin receptor mutations.

For the first time in Russia, a study of the intraspecific structure of the brown rat (Rattus norvegicus) was carried out using the mitochondrial marker of the control region (D-loop) of mtDNA. MtDNA sequences of brown rats from 8 regions of the European and Asian parts of Russia were analyzed. Three clades of rats have been identified: in the European part of Russia –1, in the Asian part – 2. Synanthropic subspecies – R. n. norvegicus is represented by european and asian lineages. The european lineage included haplotypes from the regions of central and southern Russia, and the Asian lineage included haplotypes from Eastern Siberia and the Far East. The previously described free living subspecies, R. n. caraco from the Russian Far East was represented as separate genetic lineage.

A new genus and species of fossil swallows, Miochelidon eschata gen. et sp. nov., are described from the Lower Miocene of the Baikal region. This is the only Miocene representative of the Hirundinidae and the oldest fossil record of the group. The coracoid of Miochelidon combines generalized and specialized features, suggesting a basal position in the family for the genus. The ulna has a more advanced morphology, like in modern swallow. The find indicates a widespread distribution of basal swallows in the Early Miocene.

The composition of fatty acids in the muscle tissue of the unique Central Asian carp-like fish of the Potanin Altai osman Oreoleuciscus potanini was studied for the first time. The populations of these fish in the reservoirs of the semi-desert zone (Durgun and Taishir) during the period of their formation are considered. It was shown that the content of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in O. potanini corresponds to the median value of this value in the order Cypriniformes. It has been established that the basis of the food web of the herbivorous form of this species consists of microalgae: diatoms, euglens and, possibly, chrysophytes, as well as bacteria. At the same time, the levels of bacterial biomarkers, 15–17BFA and 17:0 were significantly higher in fish in the Durgun reservoir, and the level of EPA (diatom biomarker) in O. potanini in the Taishir reservoir. The established higher values of the heavy nitrogen isotope content in the muscles of O. potanini from the Taishir reservoir are most likely associated with not yet formed benthic communities and with the incomplete diversification of the river form of the Potanin Altai Osman into lacustrine forms.

Radiosensitivity to low and medium doses of X-ray radiation (XR) and the ability to induce a radiation adaptive response (RAR) of lymphocytes during in vitro irradiation of peripheral blood of patients with cancer were studied. The criterion for cytogenetic damage was the frequency of micronuclei (MN) in cytochalasin-blocked binucleate lymphocytes in culture. It was found that the spontaneous level of cytogenetic damage in the lymphocytes of patients was 2.6 times higher than in healthy volunteers, and there was also significant interindividual variability in values compared to the control cohort. There were no differences in mean values for radiosensitivity to low and medium doses of XR between the study groups. There was no correlation between the spontaneous level of MN in lymphocytes and the radiosensitivity of individuals in both groups. RAR was induced with the same frequency and to the same extent in lymphocytes from both patients and healthy individuals.

The TREX-2 complex of eukaryotes is responsible for the export of a wide range of mRNAs from the nucleus to the cytoplasm. Previously, we showed that a subunit of the D. melanogaster TREX-2 complex, the PCID2 protein, has a domain that specifically interacts with RNA. However, it remains unknown whether other components of the complex are involved in interaction with and recognition of the target mRNA. In the present work, we determined the role of Xmas-2, the core structural subunit of the complex, in the specific recognition of ras2 mRNA fragments. In this work, we showed that Xmas-2, interacts with ras2 mRNA independently of other subunits of the complex. We showed that RNA-binding domains are located in both the N-terminal domain and the C-terminal domain of Xmas-2. However, the interaction of the protein with ras2 mRNA fragments is independent of RNA sequence and structure and is nonspecific. Thus, the Xmas-2 subunit is not involved in the recognition of specific RNA sequences by the complex.

The circadian dynamics of the expression of key genes of carotenoid metabolism (PSY2, LCYE, CrtRB1, and NCED1) in the photosynthetic tissue of tomato Solanum lycopersicum L. (cultivar Korneevsky) plants was characterized. An in silico analysis of the gene expression pattern was carried out and a high level of their transcripts was detected in the leaf tissue. qRT-PCR analysis of gene expression was performed at six time points during the day and found the highest levels of PSY2, LCYE and NCED1 transcripts in the second half of the light phase, and CrtRB1 – at the end of the dark phase. The content and composition of carotenoids in leaf tissue in the middle of the day was determined and it was shown that the leaf accumulates 1.5 times more compounds of the ɛ/β-branch of carotenoid biosynthesis pathway than compounds of the β/β-branch.