Tandem and interspersed repeats contribute to the mosaic structure of segmented duplications in the human genome

Intrachromosomal and interchromosomal segmental duplications account for more than 5% of the human genome. To analyze the processes resulting in the complex mosaic structure of duplicons, a draft human genome sequence was searched for duplicated segments of a genomic fragment of the pericentric region of the chromosome 21 short arm. The duplicons found consist of modules having paralogs in various genome regions. Module ends are flanked with various tandem or interspersed repeats, which are more unstable as compared with unique sequences. In most cases, the boundaries of duplicated segments exactly coincide with or are in close proximity to hot spots of various rearrangements within repeats or boundaries between repeats and unique sequences or between two different repeats. Homologous recombination between repetitive elements was assumed to be the major mechanism contributing to the mosaic structure of duplicons.     

Influence of physical loading on the content of intestinal microflora endotoxin in blood plasma and immunity indices to endotoxin

The content of endotoxin of Gram-negative bacteria and humoral and granulocytic immunity indices to endotoxin in sportsmen and untrained persons before and after undergoing physical load were studied. The study revealed that prior to physical load the content of intestinal microflora endotoxin in the blood stream of volunteer students increased and the humoral immunity indices to endotoxin decreased. Judging by the content of cortisol in the blood, the state of stress increased after a physical load. In the groups with good adaptation a decreased endotoxin content in the blood stream was noted, especially 24 hours after load. On the contrary, in the groups with dysadaptation the content of endotoxin in blood plasma increased after a load and was accompanied by a decrease in antibody titers and in the reserve of leukocytes capable of binding endotoxin.     

Localization and Organization of the Translational Apparatus in Mitochondrial Membranes of Astasia longa

In isolated mitochondrial membranes of Astasia longa, large and small circular substructures were observed with diameters of 1.30 and 0.35 m and thickness of 0.08 and 0.03 m, respectively. Such substructures were isolated by membrane treatment with proteolytic enzymes (proteinase K, trypsin) or by lipid solubilization with Triton X-100. After the removal of surface protein layer, we uncovered circular polyribosomes with similar diameters as those of original substructures. Polyribosomes were identified on the basis of their morphology, positive staining with uranyl acetate, a capacity for chloramphenicol-sensitive incorporation of ¹⁴C-amino acids into polypeptides, and from their buoyant density as estimated by equilibrium centrifugation in the CsCl density gradient. The conclusion is that, in mitochondrial membranes of A. longa, the translational apparatus is organized similarly to that in the membranes of chloroplasts and cyanobacteria, e.g., large and small circular polyribosomes situated within the membrane ring-shaped substructures are the basics for the formation of the latter.     

Factors causing long-term dynamics in the abundance of the Trans-Volga Great bustard (Otis tarda L.) population

The results of our survey of bustards in the southern part of the Saratov Trans-Volga region over an area of 12000 sq. km in 1990–2010 are presented; analysis of the abundance dynamics is performed; and the factors causing it are revealed. Data on the distribution of bustards over their biotopes in the period of premigration roaming are studied, and the demographic and spatial structure of the population is analyzed.     

Prevalent function of genome loci associated with development of multiple sclerosis as revealed by GWAS and eQTL analysis

We studied genome distribution of single-nucleotide polymorphisms (SNP) associated with development of multiple sclerosis and identified genome segments enriched in such polymorphisms. Some SNPs observed in identified segments are also local or distal eQTLs (expression quantitative trait loci) for a number of genes expressed in the blood or the nervous system. We analyzed lists of genes expression of which depends on these eQTLs, separately for the blood and the nervous system, and identified GO functions overrepresented in such gene lists. An antigen processing and presentation via MHC class II appeared to be the main gene functions either in the blood or in the nervous system. We identified a set of SNPs genetically linked with at least three SNPs associated with multiple sclerosis in GWAS, which includes eQTLs for all overrepresented functions. These SNPs and genes are located in a rather short locus on chromosome 14 presumably containing IGHG genes. SNPs from this genome segment affect expression of the HLA-DOB, HLA-DQA1, HLA-DQA2, and HLA-DQB1 genes both in the blood and in the nervous system. The results we obtained made it possible to suggest the mechanisms of multiple sclerosis development.     

Dynamics of the mammal fauna in steppes of the Volga-Ural interfluve over the past century

The steppe theriofauna of the Volga-Ural interfluve has been changing during the past century under the effect of both natural and anthropogenic factors. These changes have manifested themselves most clearly in the desert Caspian steppes and the dry steppes of the Transvolga Syrt Plain. A total of 66 mammal species are listed for this region. Some of them have disappeared while others have appeared anew, with their abundance ratio fluctuating significantly. Over the past 50 years, 15 new species have been recorded in the Transvolga fauna. One-third of them have come from the south and represent the desert faunal assemblage, while two-thirds are representatives of the forest assemblage that have come from the north.     

State of Birch Outliers in the Southern Trans-Urals in the Zone of High Anthropogenic Load on Natural Ecosystems

Biology Bulletin - Abstract—The results of our study of the ecosystem diversity and state of forest outliers located in the Shchuchanskii district of the Kurgan region are presented. The...