Variation of cytochrome b gene in sympatric chars from Kronotsky Lake (Kamchatka oblast)

In previously identified sympatric char forms (species) from Kronotsky Lake (Kamchatka Peninsula) and a number of other chars from the genus Salvelinus, nucleotide sequences of the mtDNA cytochrome b gene were determined and phylogenetic analysis of these forms was performed. The divergence of the cytochrome b gene in the Kronotsky char group (0.48%) coincided with the interpopulation difference estimates in northern Dolly Varden, which indicates a relatively recent divergence of the chars from Kronotsky Lake. Haplotypes of each form of the Kronotsky Lake chars are divided into two groups, which belonged to two different phylogenetic mtDNA lineages of northern Dolly Varden from Chukotka and Kamchatka. The formation of the Kronotsky char forms proved to be unrelated to the observed variability of the mtDNA cytochrome b gene.     

On mechanism of allosteric modulation of NMDA receptor via amino-terminal domains

A possible mechanism of action of the allosteric modulators of NMDA (N-methyl-d-aspartate) receptors is proposed that involves the stabilization of the twisted closed-clamshell configuration of the amino-terminal domains of GluN1 and GluN2B subunits by negative modulators while positive modulators stabilize a roughly parallel tight arrangement of these domains. These respective motions may play an important role in the transition between the open-channel and closed-channel states of the receptor. In addition, some features of the negative modulator binding site found by means of the molecular dynamics study and pocket analysis can be used in the rational design of the allosteric NMDA receptor modulators.     

Growth and photosynthetic activity of diatom Thalassiosira weissflogii at decreasing salinity

The relative yield of variable chlorophyll fluorescence (F _v/F _m), rate of photosynthetic carbon fixation (P), growth rate, and production of extracellular photosynthates (P _ec) was studied in diatom T. weissflogii in seawater with salinity decreasing from 35 to 15 and 5‰. After incubation at 5‰ for 1 day, the diatom abundance (N) decreased as a result of death of a fraction of cells, while viable cells demonstrated decreased F _v/F _m and P, P _ec was detectable, and cell division was likely inhibited. After incubation for 2 days, population started to grow, while exponential growth rate and the abundance by day 8 were lower compared to 35‰. After incubation at 15‰ for 1 day, P was higher and F _v/F _m was lower compared to 35‰. No cell death was observed and exponential growth rate insignificantly differed from that at 5‰. The value of N by day 8 was lower compared to 35‰ but higher compared to 5‰. The dependence of photosynthetic parameters and population dynamics of T. weissflogii on the relative salinity is discussed.     

The protein complex Ppz1p/Hal3p and nonsense suppression efficiency in the yeast Saccharomyces cerevisiae

It is known that nonsense suppression efficiency in yeast is controlled both genetically and epigenetically. As many components of translation machinery are represented by phosphoproteins, it depends, in particular, on the activity of kinases and phosphatases. The Ppz1p/Hal3p complex is among them. In this complex, the Ppz1p phosphatase is a catalytic subunit and Hal3p negatively regulates its function. The aim of this work was to study mechanisms which relate the activity of Ppz1p/Hal3p complex to nonsense suppression efficiency. In this study we used a genetic approach consisting of the analysis of nonsense suppression phenotype of strains over-expressing HAL3 or PPZ1 genes and also bearing deletions or mutant alleles of genes which presumably could participate in the manifestation of these over-expressions. We have shown that Hal3p inhibits not only Ppz1p, but also the homologous phosphatase Ppz2p. Our data indicate that Ppz2p is also involved in the control of nonsense suppression efficiency. In the course of search for Ppz1p target protein, it was shown that Ppz1p dephosphorylates at least two proteins participating in translation. Moreover, Ppz1p affects nonsense suppression efficiency not only due to its phosphatase activity but also due to another mechanism triggered by its interaction with Hsp70 chaperones.     

Identification in the rat olfactory epithelium new subgroup YM-1 chitinase-like protein

Novel protein with a molecular mass of ~43 kDa from rat olfactory epithelium in pathophysiological conditions was discovered. Its amino acid sequence and affiliation with the family 18 glycohydrolase subgroup of chitinase-like proteins YM-1 were determined.     

Catalogue of the ants (Hymenoptera, Formicidae) of Bulgaria

The present catalogue of the ants (Hymenoptera, Formicidae) of Bulgaria is made on a base of critical reconsideration of literature (covering the period from 1892 till 2009 and part of 2010) as well as on examination of the authors' and several museum's collections. A lot of data were omitted in the previous Bulgarian monograph on ants, lots of new data were recently added and many important additions and alterations were made due to taxonomic revisions of Eurasian Formicidae during the last three decades. Two new species are reported for the country [Temnothorax graecus (Forel, 1911) and Temnothorax cf. korbi (Emery, 1924)].This catalogue contains a list of 163 ant species belonging to 40 genera of 6 subfamilies now known from Bulgaria. Synonyms and information on the previously reported names in relevant publications are given. Known localities of the species are grouped by geographic regions. Maps with concrete localities or regions for each species were prepared. The conservation status of 13 ant species is given as they are included in IUCN Red List of Threatened Species and Bulgarian Biodiversity Act. In comparison with adjacent Balkan regions the ant fauna of Bulgaria is quite rich and its core is composed of South European elements.     

Relationships of eelpouts of genus Zoarces (Zoarcidae, Pisces) inferred from molecular genetic and morphological data

Molecular genetic and morphological analysis of eelpouts of the genus Zoarces was carried out. Based on the mitochondrial DNA sequence variation, haplotypes of notched-fin eelpout, Z. elogatus, more closely related Fedorov eelpout, Z. fedorovi, and common eelpout, Z. viviparus, as well as of Andriyashev eelpout, Z. andriashevi, were grouped in one macrocluster. Haplotypes of American eelpout, Z. americanus, and blotched eelpout, Z. gillii, clustered separately from other species. The genetic differences between Z. gillii and the other eelpout species were very high for within-genus comparisons, constituting 7.62%. Species divergence in terms of morphological characters was generally consistent with molecular genetic data and confirmed distinct isolation of American eelpout, and especially of blotched eelpout.     

Comparative Restriction Enzyme Analysis of Mitochondrial DNA in Several Populations of Lake Resident Chars of the Genus Salvelinus

Restriction enzyme analysis was employed in studying the mitochondrial DNA (mtDNA) ATPase6/ND4L region in several Northeast Asian populations of resident lake char of the genus Salvelinus. On evidence of mitotypes, genetic similarity was assumed for populations of neiva (Ueginskoe Lake), lake resident char from the northern coast of the Sea of Okhotsk (Mak-Mak Lake and Elekchanskie lakes), and dolly varden. Mitotype AAAA proved to be common for these populations. Lake char populations of the Juliet and Maxi lakes (the basin of the Kolyma River) had mitotype DBAA, which is similar to mitotype DBAB observed earlier in Taranetz char from Chukotka. The divergence between mitotypes AAAA and DBAA was estimated at 0.3%. Different origins were assumed for the lake resident char populations from the basins of the Sea of Okhotsk and of the Kolyma River, the former originating in the Pacific and the latter, in the Arctic basins.