Phylogeography and origin of freshwater populations of tubenose gobies of genus Proterorhinus (Gobiidae: Pisces) in Ponto-Caspian Basin

Representatives of the genus Proterorhinus (tubenose gobies) from the water bodies of the Ponto-Caspian Basin were examined for sequence polymorphism of the mitochondrial DNA fragment containing the cytochrome b (Cyt-b) gene. A total of ten haplotypes were discovered, which formed two groups. Thus, the data obtained indicated the existence of only two taxonomically valid phylogenetic lineages, represented by (1) marine and brackish-water populations of the Black Sea and (2) freshwater populations of the whole Ponto-Caspian Basin, along with the brackish-water population of the Caspian Sea. Based on an analysis of the tubenose goby haplotype distribution patterns, the colonization patterns of this group of fishes (phylogeography) in the freshwater drainages of Ponto-Caspian Basin are examined. It was established that the basin of the ancient Caspian Sea was the major donor area for the formation of the freshwater and brackish-water populations. In the Ponto-Caspian Basin, two centers of the tubenose gobies speciation and distribution are distinguished. One of these centers is associated with the modern northwestern part of the Black Sea, and another one is confined to the Caspian Sea. It is suggested that the modern colonization of the Volga River by tubenose goby occurred from the Caspian Sea.     

Structure Determination and Improved Model of Plant Photosystem I

Photosystem I functions as a sunlight energy converter, catalyzing one of the initial steps in driving oxygenic photosynthesis in cyanobacteria, algae, and higher plants. Functionally, Photosystem I captures sunlight and transfers the excitation energy through an intricate and precisely organized antenna system, consisting of a pigment network, to the center of the molecule, where it is used in the transmembrane electron transfer reaction. Our current understanding of the sophisticated mechanisms underlying these processes has profited greatly from elucidation of the crystal structures of the Photosystem I complex. In this report, we describe the developments that ultimately led to enhanced structural information of plant Photosystem I. In addition, we report an improved crystallographic model at 3.3-Å resolution, which allows analysis of the structure in more detail. An improved electron density map yielded identification and tracing of subunit PsaK. The location of an additional ten β-carotenes as well as five chlorophylls and several loop regions, which were previously uninterpretable, are now modeled. This represents the most complete plant Photosystem I structure obtained thus far, revealing the locations of and interactions among 17 protein subunits and 193 non-covalently bound photochemical cofactors. Using the new crystal structure, we examine the network of contacts among the protein subunits from the structural perspective, which provide the basis for elucidating the functional organization of the complex.     

An essential saccharide binding domain for the mAb 2C7 established for Neisseria gonorrhoeae LOS by ES-MS and MSn

A study of bacterial surface oligosaccharides were investigated among different strains of Neisseria gonorrhoeae to correlate structural features essential for binding to the MAb 2C7. This epitope is widely expressed and conserved in gonococcal isolates, characteristics essential to an effective candidate vaccine antigen. Sample lipooligosaccharides (LOS), was prepared by a modification of the hot phenol-water method from which de-O-acetylated LOS and oligosaccharide (OS) components were analyzed by ES-MS-CID-MS and ES-MSnin a triple quadrupole and an ion trap mass spectrometer, respectively. Previously documented natural heterogeneity was apparent from both LOS and OS preparations which was admixed with fragments induced by hydrazine and mild acid treatment. Natural heterogeneity was limited to phosphorylation and antenni extensions to the alpha-chain. Mild acid hydrolysis to release OS also hydrolyzed the beta(1-->6) glycosidic linkage of lipid A. OS structures were determined by collisional and resonance excitation combined with MS and multistep MSn which provided sequence information from both neutral loss, and nonreducing terminal fragments. A comparison of OS structures, with earlier knowledge of MAb binding, enzyme treatment, and partial acid hydrolysis indicates a generic overlapping domain for 2C7 binding. Reoccurring structural features include a Hepalpha(1-->3)Hepbeta(1-->5)KDO trisaccharide core branched on the nonreducing terminus (Hep-2) with an alpha(1-->2) linked GlcNAc (gamma-chain), and an alpha-linked lactose (beta-chain) residue. From the central heptose (Hep-1), a beta(1-->4) linked lactose (alpha-chain), moiety is required although extensions to this residue appear unnecessary.      

Proteolytic Activity of Chymotrypsin Immobilized on Selenium Nanoparticles

Chymotrypsin was immobilized as a part of hybrid organo-inorganic nanocomplexes on selenium nanoparticles in the reduction reaction of selenious acid with ascorbic acid. Chymotrypsin stabilized the selenium nanoparticles in the solution. The spectral characteristics of synthesized nanocomplexes and the proteolytic activity of immobilized chymotrypsin were studied. It was shown that the immobilized enzyme had increased proteolytic activity in an alkaline medium.     

Morphological and Genetic Diversity of Two Forms of Muksun Coregonus muksun (Salmonidae) of the Khatanga River Basin as a Key for Understanding the Phylogenetic Relationships between Muksun and Whitefish C. lavaretus

Journal of Ichthyology - Morphological analysis of muksun Coregonus muksun of the Khatanga River basin revealed that along with its typical high-density-rakered form, individuals of the...     

Effect of insulin and taurine on the potassium content of the perfused liver in irradiated rats

Effect of insulin (0.4 units/l) and taurine (0.4 g/l) on potassium transport to a perfusate was studied using perfusing rat liver isolated on the 1st and 3d days following irradiation (18.06.10(-2) C/kg). Both preparations were shown to diminish reliably the release of potassium ions from cellular structures of irradiated rat liver.     

Special traits of the genetic structure and origin of the population of vendace <Emphasis Type="Italic">Coregonus albula</Emphasis> of Pleshcheyevo Lake

Nucleotide sequences of two regions of mitochondrial DNA are analyzed, that of the ND1-fragment and that of the fragment comprising a part of the cytochrome c oxidase gene. In the population of the vendace Coregonus albula from Pleshcheyevo Lake, there are specimens possessing haplotypes considerably differing from common variants of sequences represented both in the water body under consideration and in other water bodies of the European part of Russia. The level of intrapopulation polymorphism exceeds the level between species.