Isotopic effects in the electronic spectra of tryptophan

Summary. No influence of isotopic substitution in deuterium-substituted tryptophan on the florescence excitation spectrum has previously been found out. Here, the isotopic effects of electronic excitation of deuterium-substituted tryptophan were experimentally and theoretically analyzed for first time. It was shown a short-wave shift of the UV-absorption maximum at 220 nm corresponding to the 360 cal/mol and short-wave shift for fluorescence spectrum corresponding to the 210 cal/mol. To account for this effect, the quantum chemical calculations of the geometric and electron structure, frequencies of normal vibrations and transition energies have been performed. The isotopic effects originate from the zero-point energies of ground and excited states. It was found that isotopic shifts depend on the position of isotope in the molecule and kind of transition. So, it can be utilized in the analysis of proteins structure and complexation.     

Ecological niches of species of the genus Ischnura (Odonata, Coenagrionidae) in oases of the Pamir-Alai Mountains

With development of irrigation and oases, new habitats suitable for dragonflies appeared, and unique assemblages of dragonflies were formed in artificial reservoirs. In the oases zone of the Pamir-Alai Mts., species of the genus Ischnura predominate among Zygoptera. The co-occurrence of Ischnura fountainei, I, evansi, I. elegans, I. forcipata, and I. pumilio was investigated. Divergence of ecological niches of these species is due to their adaptation to different habitats. Co-dominating species demonstrate complementation, i.e., they use the same habitat in different time intervals. The hygrothermal preferences of species determine the differences in their daily rhythms and microspatial distribution of adults.     

Cytochrome bd oxidase and nitric oxide: from reaction mechanisms to bacterial physiology

Experimental evidence suggests that the prokaryotic respiratory cytochrome bd quinol oxidase is responsible for both bioenergetic functions and bacterial adaptation to different stress conditions. The enzyme, phylogenetically unrelated to the extensively studied heme-copper terminal oxidases, is found in many commensal and pathogenic bacteria. Here, we review current knowledge on the catalytic intermediates of cytochrome bd and their reactivity towards nitric oxide (NO). Available information is discussed in the light of the hypothesis that, owing to its high NO dissociation rate, cytochrome bd confers resistance to NO-stress, thereby providing a strategy for bacterial pathogens to evade the NO-mediated host immune attack.     

The polymorphism and distribution of B chromosomes in germline and somatic cells of Tscherskia triton de Winton (Rodentia, Cricetinae)

The karyotypes of 13 greater long-tailed hamsters (Tscherskia triton de Winton, 1899) (eight males and five females) from Primorskii krai (Russia), including six males and one female from the vicinity of the city of Ussuriisk and two males and four females from the vicinity of the village of Pogranichnyi, have been studied. The karyotypes of five males (four from the vicinity of Ussuriisk and one from the vicinity of Pogranichnyi) have been found to contain one or two small acrocentric B chromosomes each. In males with B chromosomes, each germline cell contains one or two B chromosomes. The proportion of somatic cells carrying B chromosomes varies from 34.9 to 55.9% in these males. Karyological study of a total of 45 Tscherskia triton (30 males and 15 females) from Primorskii krai has been performed, B chromosomes being found in only five males (11.1%). In T. triton populations of Korea and China, also only a few animals have been found to carry one or two B chromosomes. The greater long-tailed hamster belongs to the monotypic genus Tscherskia; the animals described earlier under the names T. (Cricettilus) triton albipes Ognev, 1914 and T. (Cricettilus) triton nestor Thomas, 1907 belong to the only species in the genus, T. triton de Winton, 1899.     

New data on birds and mammals population of the Sette-Daban Mountain Ridge

Original materials on the fauna of the northern macroslope of the Sette-Daban Mountain Ridge are presented. Birds and mammals population in different habitats in the basin of the Allakh-Yun River are characterized.     

NODULE ROOT and COCHLEATA Maintain Nodule Development and Are Legume Orthologs of Arabidopsis BLADE-ON-PETIOLE Genes

During their symbiotic interaction with rhizobia, legume plants develop symbiosis-specific organs on their roots, called nodules, that house nitrogen-fixing bacteria. The molecular mechanisms governing the identity and maintenance of these organs are unknown. Using Medicago truncatula nodule root (noot) mutants and pea (Pisum sativum) cochleata (coch) mutants, which are characterized by the abnormal development of roots from the nodule, we identified the NOOT and COCH genes as being necessary for the robust maintenance of nodule identity throughout the nodule developmental program. NOOT and COCH are Arabidopsis thaliana BLADE-ON-PETIOLE orthologs, and we have shown that their functions in leaf and flower development are conserved in M. truncatula and pea. The identification of these two genes defines a clade in the BTB/POZ-ankyrin domain proteins that shares conserved functions in eudicot organ development and suggests that NOOT and COCH were recruited to repress root identity in the legume symbiotic organ.     

Distribution of cryptic shrew species of the genus Sorex (Mammalia) on the plain between the Don and Kuban rivers as inferred by molecular markers

Microsatellite and mtDNA markers have been used to identify two pairs of cryptic species Sorex araneus L. (Sorex satunini Ogn.) and Sorex minutus L. (S. volnuchini Ogn.). The new data were obtained on the distribution of these species on the plain between the Don and Kuban rivers. The shrew S. volnuchini and Caucasian mole are distributed on the plain areas up to the Eya River. The endemic species of the Caucasus, the shrews S. satunini and S. volnuchini, are widely distributed across the valleys alongside small streams on the steppe plain. Both species are most abundant on thick grasslands, bushy scrub, and deciduous woodlands. They don??t show any clear differences in habitat preferences.     

Diversity and individuality of variants of the system of B chromosomes in mice <Emphasis Type="Italic">Apodemus peninsulae</Emphasis>

A complicated population system of B chromosomes has been revealed in the karyotypes of the East-Asian mouse Apodemus peninsulae over the whole range. Based on our previous data for mice from Altai, Siberia, Pribaikal’e, and Mongolia and on the results of the present work, we infer that most of animals studied (196 out of 312, or 63%) have an individual variant of the B chromosome system. Only three mice lacked B chromosomes. New data for 44 A. peninsulae mice caught in 2000–2005 in 16 localities of seven regions of Altai, Siberia, and Pribaikal’e showed that all of them had individual variants of the system of B chromosomes due to different combinations (from 2 to 18 B chromosomes) of five classes of B macro- and microchromosomes.     

Interaction of bd-type quinol oxidase from Escherichia coli and carbon monoxide: Heme d binds CO with high affinity

Comparative studies on the interaction of the membrane-bound and detergent-solubilized forms of the enzyme in the fully reduced state with carbon monoxide at room temperature have been carried out. CO brings about a bathochromic shift of the heme d band with a maximum at 644 nm and a minimum at 624 nm, and a peak at 540 nm. In the Soret band, CO binding to cytochrome bd results in absorption decrease and minima at 430 and 445 nm. Absorption perturbations in the Soret band and at 540 nm occur in parallel with the changes at 630 nm and reach saturation at 3-5 microM CO. The peak at 540 nm is probably either beta-band of the heme d-CO complex or part of its split alpha-band. In both forms of cytochrome bd, CO reacts predominantly with heme d. Addition of high CO concentrations to the solubilized cytochrome bd results in additional spectral changes in the gamma-band attributable to the reaction of the ligand with 10-15% of low-spin heme b558. High-spin heme b595 does not bind CO even at high concentrations of the ligand. The apparent dissociation constant values for the heme d-CO complex of the membrane-bound and detergent-solubilized forms of the fully reduced enzyme are about 70 and 80 nM, respectively.