Operator-constitutive mutation in the <Emphasis Type="Italic">recA</Emphasis> gene enhances radiation resistance of <Emphasis Type="Italic">Escherichia coli</Emphasis>

Plasmid pUC19-recAo^c carrying a mutant allele of the recA gene, which plays the key role in the control of the SOS repair system and homologous recombinational repair, causes a 1.5-fold increase in radiation resistance of Escherichia coli ΔrecA cells, as compared to the wild-type recA ⁺ cells. The protective effect of this plasmid is drastically reduced in mutant lexA3 recAΔ21 deficient in the LexA protein and in induction of the SOS regulon. Plasmid pUC19-recAo^c effectively suppresses UV sensitivity of the ΔrecA mutant. Mutation recAo20 allows constitutive high-level synthesis of the RecA protein. This mutation impairs the SOS box in the operator site of the recA gene and enhances heterology of the dimer LexA binding site. These data confirm that high level of the RecA protein synthesis per se is not sufficient for the expression of γ-inducible functions and that the derepression of lexA-dependent genes, other than recA gene, is necessary for the complete induction of the SOS repair system.     

Recent evolutionary history of the bluethroat (Luscinia svecica) across Eurasia

We analysed mitochondrial DNA (mtDNA) sequences from 154 bluethroats (Luscinia svecica) sampled at 21 sites throughout much of their Eurasian range. A previously reported, single base-pair mtDNA difference between L. s. svecica and L. s. namnetum was inconsistent upon expanded geographical sampling. A significant FST value (0.29) and an isolation-by-distance effect show the existence of geographical differentiation. Phylogenetic analysis of haplotypes revealed northern and southern groups, although lineage sorting is incomplete. There was no geographical structure to the haplotype tree within groups, and currently recognized subspecies were not supported. A minimum evolution tree based on pairwise mtDNA genetic distances among average samples showed the same two broadly distributed northern and southern groups. These groups abut in the centre of the latitudinal range, and were possibly isolated by forest that developed and spread westward over the last 15 000 years. Pairwise FST values averaged 0.16 in the southern group, 0.04 in the northern group, and 0.42 between groups. Mismatch distributions suggested population growth in each group, with that in the south being more recent. In the northern group, the geographical pattern in tau suggested northward and eastward expansion. Analysis of nucleotide diversity suggested westward expansion in the southern group. The northern group had higher nucleotide diversity than the southern group, consistent with a larger current population size in the north. Given the significant FST, incompletely sorted haplotype tree, and broadly patterned minimum evolution tree, L. svevica appears to represent a species at an intermediate stage of differentiation between panmixia and reciprocal monophyly.     

Evaluation of the system for controlling the quality of the HBsAg detection in the system of screening laboratories

The two-stage control system, ensuring the high quality of serological investigations in the network of screening laboratories in Moscow was developed and introduced into practice. At the first stage the entry control of the quality of the test system for the detection of HbsAg, coming to the screening laboratories, is made in the reference laboratory with the use of specially developed "representative" panels, as well as the test systems for comparison ("reference" test systems). Then "minipanels" are formed from specimens included into the "representative" panels, which are used for the evaluation of the quality of laboratory investigations made in the screening laboratories. The high quality of such system for controlling the quality of the detection of HBsAg in the screening laboratories of Moscow is shown.     

The calcium-phosphate-induced fusion of human erythrocytes

The calcium-phosphate-induced fusion of normal human erythrocytes with those having increased (above physiological) levels of intracellular ATP was studied. Fusion of erythrocytes was markedly enhanced in the case of increased content of intracellular ATP. Fusion of such erythrocytes results in formation of giant cells up to 130 microm in diameter. Dithiothreitol practically completely inhibited fusion of erythrocytes with normal ATP content and markedly lowered it between those with increased ATP content.     

Entropy and GC Content in the beta-esterase gene cluster of the Drosophila melanogaster subgroup

We perform spectral entropy and GC content analyses in the beta-esterase gene cluster, including the Est-6 gene and the psiEst-6 putative pseudogene, in seven species of the Drosophila melanogaster species subgroup. psiEst-6 combines features of functional and nonfunctional genes. The spectral entropies show distinctly lower structural ordering for psiEst-6 than for Est-6 in all species studied. Our observations agree with previous results for D. melanogaster and provide additional support to our hypothesis that after the duplication event Est-6 retained the esterase-coding function and its role during copulation, while psiEst-6 lost that function but now operates in conjunction with Est-6 as an intergene. Entropy accumulation is not a completely random process for either gene. Structural entropy is nucleotide dependent. The relative normalized deviations for structural entropy are higher for G than for C nucleotides. The entropy values are similar for Est-6 and psiEst-6 in the case of A and T but are lower for Est-6 in the case of G and C. The GC content in synonymous positions is uniformly higher in Est-6 than in psiEst-6, which agrees with the reduced GC content generally observed in pseudogenes and nonfunctional sequences. The observed differences in entropy and GC content reflect an evolutionary shift associated with the process of pseudogenization and subsequent functional divergence of psiEst-6 and Est-6 after the duplication event.     

Release of nucleic acids by eukaryotic cells in tissue culture

Extracellular nucleic acids in cultures of A431 and HeLa cells were investigated. The data obtained demonstrate the presence of high weight DNA and RNA in the extracellular medium. Temporal changes of extracellular nucleic acids levels in growth medium were investigated.     

Elite athletes’ genetic predisposition for altered risk of complex metabolic traits

Background

Genetic variants may predispose humans to elevated risk of common metabolic morbidities such as obesity and Type 2 Diabetes (T2D). Some of these variants have also been shown to influence elite athletic performance and the response to exercise training. We compared the genotype distribution of five genetic Single Nucleotide Polymorphisms (SNPs) known to be associated with obesity and obesity co-morbidities (IGF2BP2 rs4402960, LPL rs320, LPL rs328, KCJN rs5219, and MTHFR rs1801133) between athletes (all male, n = 461; endurance athletes n = 254, sprint/power athletes n = 207), and controls (all male, n = 544) in Polish and Russian samples. We also examined the association between these SNPs and the athletes’ competition level (‘elite’ and ‘national’ level). Genotypes were analysed by Single-Base Extension and Real-Time PCR. Multinomial logistic regression analyses were conducted to assess the association between genotypes and athletic status/competition level.

Results

IGF2BP2 rs4402960 and LPL rs320 were significantly associated with athletic status; sprint/power athletes were twice more likely to have the IGF2BP2 rs4402960 risk (T) allele compared to endurance athletes (OR = 2.11, 95% CI = 1.03-4.30, P <0.041), and non-athletic controls were significantly less likely to have the T allele compared to sprint/power athletes (OR = 0.62, 95% CI =0.43-0.89, P <0.0009). The control group was significantly more likely to have the LPL rs320 risk (G) allele compared to endurance athletes (OR = 1.26, 95% CI = 1.05-1.52, P <0.013). Hence, endurance athletes were the “protected” group being significantly (p < 0.05) less likely to have the risk allele compared to sprint/power athletes (IGF2BP2 rs4402960) and significantly (p < 0.05) less likely to have the risk allele compared to controls (LPL rs320). The other 3 SNPs did not show significant differences between the study groups.

Conclusions

Male endurance athletes are less likely to have the metabolic risk alleles of IGF2BP2 rs4402960 and LPL rs320, compared to sprint/power athletes and controls, respectively. These results suggest that some SNPs across the human genome have a dual effect and may predispose endurance athletes to reduced risk of developing metabolic morbidities, whereas sprint/power athletes might be predisposed to elevated risk.     

Sub-fossil beetle assemblages associated with the "mammoth fauna" in the Late Pleistocene localities of the Ural Mountains and West Siberia

The distribution of beetles at the end of the Middle Pleninglacial (=terminal Quaternary) was examined based on sub-fossil material from the Ural Mountains and Western Siberia, Russia. All relevant localities of fossil insects have similar radiocarbon dates, ranging between 33,000 and 22,000 C14 years ago. Being situated across the vast territory from the southern Ural Mountains in the South to the middle Yamal Peninsula in the North, they allow latitudinal changes in beetle assemblages of that time to be traced. These beetles lived simultaneously with mammals of the so-called "mammoth fauna" with mammoth, bison, and wooly rhinoceros, the often co-occurring mega-mammalian bones at some of the sites being evidence of this. The beetle assemblages found between 59° and 57°N appear to be the most interesting. Their bulk is referred to as a "mixed" type, one which includes a characteristic combination of arcto-boreal, boreal, steppe and polyzonal species showing no analogues among recent insect complexes. These peculiar faunas seem to have represented a particular zonal type, which disappeared since the end of the Last Glaciation to arrive here with the extinction of the mammoth biota. In contrast, on the sites lying north of 60°N, the beetle communities were similar to modern sub-arctic and arctic faunas, yet with the participation of some sub-boreal steppe components, such as Poecilus ravus Lutshnik and Carabus sibiricus Fischer-Waldheim. This information, when compared with our knowledge of synchronous insect faunas from other regions of northern Eurasia, suggests that the former distribution of beetles in this region could be accounted for both by palaeo-environmental conditions and the impact of grazing by large ruminant mammals across the so-called "mammoth savannas".     

Computer System for Analysis of Molecular Evolution Modes (SAMEM): analysis of molecular evolution modes at deep inner branches of the phylogenetic tree

SAMEM (System for Analysis of Molecular Evolution Modes), a web-based pipeline system for inferring modes of molecular evolution in genes and proteins (http://pixie.bionet.nsc.ru/samem/), is presented. Pipeline 1 performs analyses of protein-coding gene evolution; pipeline 2 performs analyses of protein evolution; pipeline 3 prepares datasets of genes and/or proteins, performs their primary analysis, and builds BLOSUM matrices; pipeline 4 checks if these genes really are protein-coding. Pipeline 1 has an all-new feature, which allows the user to obtain K(R)/K(C) estimates using several different methods. An important feature of pipeline 2 is an original method for analyzing the rates of amino acid substitutions at the branches of a phylogenetic tree. The method is based on Markov modeling and a non-parametric permutation test, which compares expected and observed frequencies of amino acid substitutions, and infers the modes of molecular evolution at deep inner branches.