Mitochondrial DNA polymorphism of atlantic cod of the Barents and White seas

High level of intraspecific polymorphism of the mtDNA cytochrome b gene in the Atlantic cod Gadus morhua L. from the northeastern part of the species range (Barents and White seas) is detected. The absence of genetic differentiation between the samples from different areas of the Norwegian and Barents seas is shown, and the fact that these samples belong to the same population of Northeast Arctic cod is confirmed. Significant differences in the frequences of mitochondrial DNA haplotypes between the cod from the Barents and White seas, as well as from the northwestern part of the range, are found. The cod Gadus morhua kildinensis Derjugin, 1920 from Mogilnoye Lake and Gadus morhua marisalbi Derjugin, 1920 from the White Sea were revealed to have common haplotypes with the cod from the Barents Sea, confirming the recent origin of these forms from the Atlantic cod G. morhua.     

Study of the formation,stability, and X-ray emission of the Z-pinch formed during implosion of fiber arrays at the Angara-5-1 facility

Results from experimental studies on the implosion of arrays made of kapron fibers coated with different metals (Al, In, Sn, and Bi) are presented. It is shown that the power, total energy, and spectrum of radiation emitted by the imploding array depend on the number of metallized fibers and the mass of the metal layer deposited on them but are independent of the metal characteristics (density, atomic number, etc.). Analysis of frame X-ray images shows that the Z-pinches formed in the implosion of metallized kapron fiber arrays are more stable than those formed in wire arrays and that MHD perturbations in them develop at a slower growth rate. Due to the lower rate of plasma production from kapron fibers, the plasma formed at the periphery of the array forms a layer that plays the role of a hohlraum wall partially trapping soft X-ray emission of the Z-pinch formed in the implosion of the material of the deposited metal layer. The closure of the anode aperture doubles the energy of radiation emitted in the radial direction.     

Characterization of the mitochondrial genome of the MAX1 type of cytoplasmic male-sterile sunflower

Background

More than 70 cytoplasmic male sterility (CMS) types have been identified in Helianthus, but only for less than half of them, research of mitochondrial organization has been conducted. Moreover, complete mitochondrion sequences have only been published for two CMS sources – PET1 and PET2. It has been demonstrated that other sunflower CMS sources like MAX1, significantly differ from the PET1 and PET2 types. However, possible molecular causes for the CMS induction by MAX1 have not yet been proposed. In the present study, we have investigated structural changes in the mitochondrial genome of HA89 (MAX1) CMS sunflower line in comparison to the fertile mitochondrial genome.

Results

Eight significant major reorganization events have been determined in HA89 (MAX1) mtDNA: one 110 kb inverted region, four deletions of 439 bp, 978 bp, 3183 bp and 14,296 bp, respectively, and three insertions of 1999 bp, 5272 bp and 6583 bp. The rearrangements have led to functional changes in the mitochondrial genome of HA89 (MAX1) resulting in the complete elimination of orf777 and the appearance of new ORFs - orf306, orf480, orf645 and orf1287. Aligning the mtDNA of the CMS sources PET1 and PET2 with MAX1 we found some common reorganization features in their mitochondrial genome sequences.

Conclusion

The new open reading frame orf1287, representing a chimeric atp6 gene, may play a key role in MAX1 CMS phenotype formation in sunflower, while the contribution of other mitochondrial reorganizations seems to appear negligible for the CMS development.

     

Genetic drift in range expansions is very sensitive to density dependence in dispersal and growth

Theory predicts rapid genetic drift during invasions, yet many expanding populations maintain high genetic diversity. We find that genetic drift is dramatically suppressed when dispersal rates increase with the population density because many more migrants from the diverse, high‐density regions arrive at the expansion edge. When density dependence is weak or negative, the effective population size of the front scales only logarithmically with the carrying capacity. The dependence, however, switches to a sublinear power law and then to a linear increase as the density dependence becomes strongly positive. We develop a unified framework revealing that the transitions between different regimes of diversity loss are controlled by a single, universal quantity: the ratio of the expansion velocity to the geometric mean of dispersal and growth rates at expansion edge. Our results suggest that positive density dependence could dramatically alter evolution in expanding populations even when its contribution to the expansion velocity is small.     

Dynamic evaluation of blood flow microcirculation by combined use of the laser Doppler flowmetry and high‐speed videocapillaroscopy methods

The dynamic light scattering methods are widely used in biomedical diagnostics involving evaluation of blood flow. However, there exist some difficulties in quantitative interpretation of backscattered light signals from the viewpoint of diagnostic information. This study considers the application of the high‐speed videocapillaroscopy (VCS) method that provides the direct measurement of the red blood cells (RBCs) velocity into a capillary. The VCS signal presents true oscillation nature of backscattered light caused by moving RBCs. Thus, the VCS signal can be assigned as a reference one with respect to more complicated signals like in laser Doppler flowmetry (LDF). An essential correlation between blood flow velocity oscillations in a separate human capillary and the integral perfusion estimate obtained by the LDF method has been found. The observation of blood flow by the VCS method during upper arm occlusion has shown emergence of the reverse blood flow effect in capillaries that corresponds to the biological zero signal in the LDF. The reverse blood flow effect has to be taken into account in interpretation of LDF signals.      

Antiamoebin I in methanol solution: rapid exchange between right-handed and left-handed 3(10)-helical conformations

Antiamoebin I (Aam-I) is a membrane-active peptaibol antibiotic isolated from fungal species belonging to the genera Cephalosporium, Emericellopsis, Gliocladium, and Stilbella. Antiamoebin I has the amino acid sequence: Ac-Phe(1)-Aib-Aib-Aib-Iva-Gly-Leu-Aib(8)-Aib-Hyp-Gln-Iva-Hyp-Aib-Pro-Phl(16). By using the uniformly (13)C,(15)N-labeled sample of Aam-I, the set of conformationally dependent J couplings and (3h)J(NC) couplings through H-bonds were measured. Analysis of these data along with the data on magnetic nonequivalence of the (13)C(beta) nuclei (Deltadelta((13)C(beta))) in Aib and Iva residues allowed us to draw the univocal conclusion that the N-terminal part (Phe(1)-Gly(6)) of Aam-I in MeOH solution is in fast exchange between the right-handed and left-handed 3(10)-helical conformations, with an approximately equal population of both states. An additional conformational exchange process was found at the Aib(8) residue. The (15)N-NMR-relaxation and CD-spectroscopy measurements confirmed these findings. Molecular modeling and Monte Carlo simulations revealed that both exchange processes are correlated and coupled with significant hinge-bending motions around the Aib(8) residue. Our results explain relatively low activity of Aam-I with respect to other 15-amino acid residue peptaibols (for example, zervamicin) in functional and biological tests. The high dynamic 'propensity' possibly prevents both initial binding of the antiamoebin to the membrane and subsequent formation of stable ionic channels according to the barrel-stave mechanism.     

N-terminal extension of Saccharomyces cerevisiae translation termination factor eRF3 influences the suppression efficiency of sup35 mutations

The eukaryotic translation termination factor eRF3 stimulates release of nascent polypeptides from the ribosome in a GTP-dependent manner. In most eukaryotes studied, eRF3 consists of an essential, conserved C-terminal domain and a nonessential, nonconserved N-terminal extension. However, in some species, this extension is required for efficient termination. Our data show that the N-terminal extension of Saccharomyces cerevisiae eRF3 also participates in regulation of termination efficiency, but acts as a negative factor, increasing nonsense suppression efficiency in sup35 mutants containing amino acid substitutions in the C-terminal domain of the protein.     

Effect of bedaquiline on the functions of rat liver mitochondria

The paper considers the effects of bedaquiline (BDQ), an antituberculous preparation of the new generation, on rat liver mitochondria. It was shown that 50?μM BDQ inhibited mitochondrial respiration measured with substrates of complexes I and II (glutamate/malate and succinate/rotenone systems respectively) in the states V₃ and V_DNP. At the same time, at concentrations below 50?μM, BDQ slightly stimulated respiration with substrates of complex I in the state V₂. BDQ was also found to suppress, in a dose-dependent manner, the activity of complex II and the total activity of complexes II?+?III of the mitochondrial transport chain. It was discovered that at concentrations up to 10?μM, BDQ inhibited H₂O₂ production in mitochondria. BDQ (10–50?μM) suppressed the opening of Ca²⁺-dependent CsA-sensitive mitochondrial permeability transition pore. The latter was revealed experimentally as the inhibition of Ca²⁺/P_i-dependent swelling of mitochondria, suppression of cytochrome c release, and an increase in the Ca²⁺ capacity of the organelles. BDQ also decreased the rate of mitochondrial energy-dependent K⁺ transport, which was evaluated by the energy-dependent swelling of mitochondria in a K⁺ buffer and DNP-induced K⁺ efflux from the organelles. The possible mechanisms of BDQ effect of rat liver mitochondria are discussed.     

Inter- and Intra-Species Relationships of Greenland Halibut Reinhardtius hippoglossoides (Pleuronectidae) Based on the Analysis of Nuclear and Mitochondrial Genetic Markers

Journal of Ichthyology - Samples of Greenland halibut Reinhardtius hippoglossoides (Jordan and Snyder, 1901) from the Atlantic, Arctic, and Pacific Oceans were compared using eight microsatellite...