Taxonomic composition and distribution of soft-walled monothalamid foraminifera in the area of Zernov’s Phyllophora Field (NW Black Sea)

We studied assemblages of soft-walled, single-chambered foraminifera (monothalamids) at eight stations in the area of Zernov's Phyllophora Field (ZPF) on the NW continental shelf of the Black Sea. This work is based on samples collected during Cruise 70 of the RV Professor Vodyanitsky and provides the first analysis of the taxonomic composition of monothalamids from this region. These delicate, poorly known foraminifera were found at all stations in the studied area. They were represented by nine forms that are identified to species or genus level as well as 14 undescribed species, nine of which are found in the Black Sea for the first time. Four species, Psammophaga sp., Vellaria pellucida, Goodayia rostellata and Krymia fusiformis, were most abundant, with Psammophaga sp. being the dominant species overall. Previous studies have suggested a link between members of this genus and eutrophication. There are a number of taxonomic parallels between these ZPF assemblages and those from the Adriatic Sea, e.g. the occurrence of the genera Goodayia, Psammophaga and Vellaria, although it is possible that some other taxa are endemic to the Black Sea.     

Primary mono- and bis-sulfonamides obtained via regiospecific sulfochlorination of N-arylpyrazoles: inhibition profile against a panel of human carbonic anhydrases

A diverse set of mono- and bis-sulfonamide was obtained via a direct, chemoselective sulfochlorination of readily available yet hitherto unexplored N-arylpyrazole template. Biochemical profiling of compounds thus obtained against a panel of human carbonic anhydrases (hCA I, hCA II, hCA IV and hCA VII) revealed a number of leads that are promising from the isoform selectivity prospective and exhibit potent inhibition profile (from nanomolar to micromolar range). The observed SAR trends have been rationalized by in silico docking of selected compounds into the active site of all four isoforms. The results reported in this paper clearly attest to the power of direct sulfochlorination as the means to create carbonic anhydrase focused sets in order to identify isoform selective inhibitors of closely related enzymes.     

Trophic resource partitioning by sympatric ecomorphs of Schizopygopsis (Cyprinidae) in a young Pamir Mountain lake: preliminary results

Ichthyological Research - Four sympatric ecomorphs – detritivorous, predator, benthivorous, and phytophagous – of the cyprinid fish Schizopygopsis stolickai were recorded in a young...     

Synthesis of 1,2-cis- and 1,2-trans-glycosides of 2-acetamido-4,6-O-benzylidene-2-deoxy-d-glucopyranose by anomeric O-alkylation

The reaction of a partially protected 1-hydroxy derivative of N-acetyl-d-glucosamine with benzyl bromide under conditions of anomeric O-alkylation was studied. It was found that the stereoselectivity of the reaction depended on the nature of the alkali metal cation constituent of a transient ion pair. The substitution of the Li⁺ cation for K⁺ or complexation with a crown ether allowed the steric outcome to be shifted from β- to α-selectivity.     

Ultrastructural patterns of photoacclimation and photodamage to photosynthetic algae cell under environmental stress

In oxygenic phototrophs including unicellular algae, acclimation to and damage by diverse environmental stresses induce profound changes in the ultrastructural organization of the cell. These alterations reflect acclimation of the photosynthetic apparatus to unfavorable conditions (mainly reduction of the chloroplast and its membranal system) and rewiring of the photo‐fixed carbon fluxes in the cell. These changes, eventually pursuing mitigation of the photooxidative damage risk, are manifested by the formation of diverse carbon‐rich inclusions. Although the physiological and molecular basis of these processes are well understood, the ultrastructural manifestations of the stress responses are often fragmented and frequently controversial. This minireview attempts to generalize on the ultrastructural patterns accompanying stresses in the photosynthetic cell, involving the concerted rearrangements of its assimilatory and storage compartments. The changes characteristic of normal functioning and emergency reduction of the chloroplast thylakoids under harsh stress are also addressed. Special attention is paid to the manifestations of the engagement of photoprotection via active (energy‐dependent non‐photochemical quenching) and passive mechanisms (e.g. optical shielding by secondary carotenoids). We also underline the potentially important role of autophagy‐like processes and provide a more integral view of ultrastructural rearrangements under stress.     

Intranasal insulin affects adenyl cyclase system in rat tissues in neonatal diabetes

The changes in hormone-regulated adenylyl cyclase (AC) signaling system implicated in control of the nervous, cardiovascular and reproductive systems may contribute to complications of diabetes mellitus (DM). We investigated the functional state of AC system in the brain, myocardium, ovary and uterus of rats with neonatal DM and examined the influence of intranasally administered insulin on the sensitivity of this system to biogenic amines and polypeptide hormones. The regulatory effects of somatostatin and 5-HT_1BR-agonist 5-nonyloxytryptamine acting via G_i protein-coupled receptors were significantly decreased in DM and partially restored in insulin-treated rats. The effects of hormones, activators of AC, are changed in tissue- and receptorspecific manner, and intranasal insulin restored the effects rather close to the level in control. In insulin-treated non-diabetic rats, AC stimulating effects of isoproterenol and relaxin in the myocardium and of human chorionic gonadotropin in the ovaries were decreased, while the effects of hormones, inhibitors of AC, were increased. These data indicate that with intranasal insulin, Gi protein-mediated signaling pathways continue to gain strength. The obtained data on the influence of hormones on AC system in the brain, myocardium, ovary and uterus allow looking anew into the mechanisms of therapeutic effects of intranasal insulin.     

Phylogeography of Asian sockeye salmon (Oncorhynchus nerka) based on analysis of mtDNA control region polymorphism

Analysis of the contemporary geographic distributions of mtDNA haplotypic diversity of sockeye salmon (Oncorhynchus nerka Walbaum) on the Asian part of its range and consideration of possible scenarios for microevolution of the species were performed. In total, 172 specimens of sockeye salmon from different rivers of Kamchatka, Chukotka, north coast of the Sea of Okhotsk, and from the Kuril Islands were analyzed using the entire mtDNA control region (1,010 bp) sequencing. After multiple alignments of the sequences 16 polymorphic sites were identified. Most of substitutions were detected in the first and the last thirds of the D-loop sequence, as well as one insertion was registered in the poly-T region. Two mass haplotypes (Hap_1_10T and Hap_2_13T) were revealed; they were present in most samples and differed by three substitutions and two indels. All the sequence variants were distributed among two haplogroups in compliance with the mass haplotypes. The star-shaped topology of the MST-tree points to a rapid increase in the diversity of groups, indicating a rapid expansion of the species after its number reducing in the past. The diversity of the first haplogroup was higher, but its main fraction fell on the samples from the middle reach of Kamchatka River, which seems to be a refugium during the Late Pleistocene glaciation. Presence of both haplogroups in most populations in approximately equal proportions indicates that the entire Asian part of the sockeye salmon range is a zone of secondary contact. We hypothesize that Hap_2_13T had more ancient origin and the Hap_1_10T was formed somewhat later, apparently in Asia, because almost all transitional forms between the haplogroups were found in Iturup Island populations.     

MPM motifs of the yeast SKT protein Trk1 can assemble to form a functional K+-translocation system

The yeast Trk1 polypeptide, like other members of the Superfamily of K Transporters (SKT proteins) consists of four Membrane-Pore-Membrane motifs (MPMs A-D) each of which is homologous to a single K-channel subunit. SKT proteins are thought to have evolved from ancestral K-channels via two gene duplications and thus single MPMs might be able to assemble when located on different polypeptides. To test this hypothesis experimentally we generated a set of partial gene deletions to create alleles encoding one, two, or three MPMs, and analysed the cellular localisation and interactions of these Trk1 fragments using GFP tags and Bimolecular Fluorescence Complementation (BiFC). The function of these partial Trk1 proteins either alone or in combinations was assessed by expressing the encoding genes in a K⁺-uptake deficient strain lacking also the K-channel Tok1 (trk1,trk2,tok1Δ) and (i) analysing their ability to promote growth in low [K⁺] media and (ii) by ion flux measurements using “microelectrode based ion flux estimation” (MIFE). We found that proteins containing only one or two MPM motifs can interact with each other and assemble with a polypeptide consisting of the rest of the Trk system to form a functional K⁺-translocation system.     

Blood pressure and survival of a Chromosome 7 congenic strain bred from Dahl rats

11β-hydroxylase (Cyp11b1) mutations were previously linked to altered steroid biosynthesis and blood pressure in Dahl salt-resistant (R) and Dahl salt-sensitive (S) rats. In the present work, interval mapping identified a putative blood pressure quantitative trait locus (QTL) near Cyp11b1 in an F₁(S×R)×S population (LOD = 2.0). Congenic rats (designated S.R-Cyp11b) were constructed by introgressing the R-rat Cyp11b1 allele into the S strain. S.R-Cyp11b rats had significantly lower blood pressure and heart weight compared with S rats, proving the existence of a blood pressure QTL on Chromosome (Chr) 7 despite the fact that QTL linkage analysis of blood pressure never achieved stringent statistical criteria for significance. To test the effects of the introgressed region on blood pressure and survival, S.R.-Cyp11b and S rats were maintained on a 4% NaCl diet until they died or became moribund. Analysis of variance (ANOVA) indicated significant strain differences in blood pressure and days survived (P < 0.0001 for both) as well as gender differences in days survived (P = 0.0003). Kaplan-Meier survival analysis also found significant strain (P < 0.0001) and gender (P = 0.007) differences in days survived. However, when the effects of blood pressure were removed, significant strain differences in survival essentially disappeared. This suggests that the increased survival of S.R-Cyp11b rats was largely due to their decreased blood pressure and thus strongly corroborates the existence of a blood pressure QTL on Chr 7 near or at Cyp11b1. Received: 7 April 1997 / Accepted: 10 August 1997