Abundance of the Transvolga Population of Great Bustard (Otis tarda L.)

We studied the abundance, spatial structure, and demographic parameters of the Transvolga population of the great bustard and the connections of this species to habitats during relocations preceding migration. The data were obtained by monitoring a test area of 1200000 hectares in 1998–2000. Time-related changes in the structure of great bustard habitats in the Saratov Transvolga Region in the 20th century are described, and the mechanisms underlying changes in the species connection to habitats under the influence of anthropogenic factors are proposed.     

Lotus corniculatus nodulation specificity is changed by the presence of a soybean lectin gene

Plant lectins have been implicated as playing an important role in mediating recognition and specificity in the Rhizobium-legume nitrogen-fixing symbiosis. To test this hypothesis, we introduced the soybean lectin gene Le1 either behind its own promoter or behind the cauliflower mosaic virus 35S promoter into Lotus corniculatus, which is nodulated by R. loti. We found that nodulelike outgrowths developed on transgenic L. corniculatus plant roots in response to Bradyrhizobium japonicum, which nodulates soybean and not Lotus spp. Soybean lectin was properly targeted to L. corniculatus root hairs, and although infection threads formed, they aborted in epidermal or hypodermal cells. Mutation of the lectin sugar binding site abolished infection thread formation and nodulation. Incubation of bradyrhizobia in the nodulation (nod) gene-inducing flavonoid genistein increased the number of nodulelike outgrowths on transgenic L. corniculatus roots. Studies of bacterial mutants, however, suggest that a component of the exopolysaccharide surface of B. japonicum, rather than Nod factor, is required for extension of host range to the transgenic L. corniculatus plants.     

Recent fauna of ground-nesting birds in Transvolga steppes and its dynamics in the 20th century

It is shown that the structure of the ground-nesting bird fauna in Transvolga steppes has changed during the 20th century. The complex of lark species characteristic of true and dry steppe has disappeared because of climate change and impact of economic activity (the establishment of windbreak and roadside forest strips), which has provided for a sharp increase in the abundance of corvid birds.     

Oxidation of thiamine on reaction with nitrogen dioxide generated by ferric myoglobin and hemoglobin in the presence of nitrite and hydrogen peroxide

It is shown that nitrogen dioxide oxidizes thiamine to thiamine disulfide, thiochrome, and oxodihydrothiochrome (ODTch). The latter is formed during oxidation of thiochrome by nitrogen dioxide. Nitrogen dioxide was produced by incubation of nitrite with horse ferric myoglobin and human hemoglobin in the presence of hydrogen peroxide. After addition of tyrosine or phenol to aqueous solutions containing oxoferryl forms of the hemoproteins, thiamine, and nitrite, the yield of thiochrome greatly increased, whereas the yield of ODTch decreased. In the presence of high concentrations of tyrosine or phenol compounds ODTch was not formed at all. The neutral form of thiamine with the closed thiazole cycle and minor tricyclic form of thiamine do not enter the heme pocket of the protein and do not interact with the oxoferryl heme complex Fe(IV=O) or porphyrin radical. The tricyclic form of thiamine is oxidized to thiochrome by tyrosyl radicals located on the surface of the hemoprotein. The thiol form of thiamine is oxidized to thiamine disulfide by both hemoprotein tyrosyl radicals and oxoferryl heme complexes. Nitrite and also tyrosine, tyramine, and phenol readily penetrate into the heme pocket of the protein and reduce the oxyferryl complex to ferric cation. These reactions yield nitrogen dioxide as well as tyrosyl and phenoxyl radicals of tyrosine molecules and phenol compounds, respectively. Tyrosyl and phenoxyl radicals of low molecular weight compounds oxidize thiamine only to thiochrome and thiamine disulfide. The effect of oxoferryl forms of myoglobin and hemoglobin, nitrogen dioxide, and phenol on thiamine oxidative transformation as well as antioxidant properties of the hydrophobic thiamine metabolites thiochrome and ODTch are discussed.     

Thiamine inhibits formation of dityrosine,a specific marker of oxidative injury,in reactions catalyzed by oxoferryl forms of hemoglobin

Effects of thiamine and its derivatives on inhibition of dityrosine formation were studied in reactions catalyzed by oxoferryl forms of hemoglobin. At high thiamine concentrations, a complete inhibition of dityrosine formation was observed due to interaction of tyrosyl radicals with thiamine tricyclic and thiol forms. In neutral and alkaline media, tyrosyl radicals oxidized thiamine to thiochrome, oxodihydrothiochrome, and thiamine disulfide. In the absence of tyrosine, oxoferryl forms of hemoglobin manifested peroxidase activity towards thiamine and its phosphate esters by inducing their oxidation to disulfide compounds, thiochrome, oxodihydrothiochrome, and their phosphate esters, respectively, in neutral media. Thiamine and its phosphate esters were oxidized by both oxoferryl forms of hemoglobin, viz., +*Hb(IV=O) (compound I with an additional radical on the globin) and Hb(IV=O) (compound II). Putative mechanisms of thiamine conversions under oxidative stress and the protective role of hydrophobic thiamine metabolites are discussed.     

An RNA folding method capable of identifying pseudoknots and base triples

MOTIVATION: Recently, we described a Maximum Weighted Matching (MWM) method for RNA structure prediction. The MWM method is capable of detecting pseudoknots and other tertiary base-pairing interactions in a computationally efficient manner (Cary and Stormo, Proceedings of the Third International Conference on Intelligent Systems for Molecular Biology, pp. 75-80, 1995). Here we report on the results of our efforts to improve the MWM method's predictive accuracy, and show how the method can be extended to detect base interactions formerly inaccessible to automated RNA modeling techniques. RESULTS: Improved performance in MWM structure prediction was achieved in two ways. First, new ways of calculating base pair likelihoods have been developed. These allow experimental data and combined statistical and thermodynamic information to be used by the program. Second, accuracy was improved by developing techniques for filtering out spurious base pairs predicted by the MWM program. We also demonstrate here a means by which the MWM folding method may be used to detect the presence of base triples in RNAs. AVAILABILITY: http://www.cshl.org/mzhanglab/tabaska/j axpage. html CONTACT: tabaska@cshl.org      

Antivitamin activity of O-acyloxythiamine disulfides

B1-antivitamin activity of symmetrical oxythiamine disulphide esters with succinic and o-phthalic acids has been studied in experiments on albino mice. It is shown that O-acyloxythiamine disulphides exert more profound and prolonged inhibitory effect on the transketolase activity in the animal body in comparison with the known antagonist of vitamin B1, oxythiamine, and the initial oxythiamine disulphide.     

Changes in the population structure of the red-tailed Libyan jird as affected by toxicants

The kind of the regulating agent for the quantitative control of the epidemically dangerous species depends on the concrete tasks. The poison of the critical action causes a strong, but short-time effect. The pesticide inhibiting the reproductive system of the rodents exerts long and profound influence on the population structure.