Investigation of the possibility of exceeding the Greenwald density limit during ECRH in T-10

In T-10 experiments, attempts were made to significantly exceed the Greenwald limit $\bar n_{Gr} $ during high-power (P _ab=750 kW) electron-cyclotron resonance heating (ECRH) and gas puffing. Formally, the density limit $(\bar n_e )_{\lim } $ exceeding the Greenwald limit $({{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }} = 1.8)$ was achieved for q _L=8.2. However, as q _L decreased, the ratio ${{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }}$ also decreased, approaching unity at q _L≈3. It was suggested that the “current radius” (i.e., the radius of the magnetic surface enclosing the bulk of the plasma current I _p), rather than the limiter radius, was the parameter governing the value of $(\bar n_e )_{\lim } $ . In the ECRH experiments, no substantial degradation of plasma confinement was observed up to $\bar n_e \sim 0.9(\bar n_e )_{\lim } $ regardless of the ratio ${{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }}$ . In different scenarios of the density growth up to $(\bar n_e )_{\lim } $ , two types of disruptions related to the density limit were observed.     

Living planktonic foraminifera in the Fram Strait (Arctic): absence of diel vertical migration during the midnight sun

The timing of vertical migration in planktonic foraminifera (ex. ontogenetic, diel) is still an open debate. This work aims to investigate the diel vertical migration (DVM) of Neogloboquadrina pachyderma (N. pachyderma) and Turborotalita quinqueloba (T. quinqueloba) in the Arctic during the midnight sun. N. pachyderma and T. quinqueloba dominate the total assemblage in the cold Polar Water and warmer North Atlantic Water masses, respectively. Foraminifera were collected at several depths along the Fram Strait. Afterwards sampling was performed at the same station for 24 h at continuous and discrete time intervals. Results show no evidence of planktonic foraminifera DVM since there was no significant variability in the abundance and size distribution during the 24-h collection period. This finding provides information to improve the interpretation of foraminifera in paleoclimatic works. This is especially relevant in the Fram Strait as paleoclimatic studies in this region are fundamental to investigating the history of the Atlantic water inflow into the Arctic Ocean.     

Hydrodynamic properties of cyclodextrin molecules in dilute solutions

Three well-known representatives of the cyclodextrin family were completely characterized by molecular hydrodynamics methods in three different solvents. For the first time the possibility of an estimation of velocity sedimentation coefficients s between 0.15 and 0.5 S by the numerical solution of the Lamm equation is shown. Comparison of the experimental hydrodynamic characteristics of the cyclodextrins with theoretical calculations for toroidal molecules allows an estimation of the thickness of the solvent layers on the surface of cyclodextrin molecules.     

Screening of population genetic SCAR markers for mykiss <Emphasis Type="Italic">Parasalmo</Emphasis> (<Emphasis Type="Italic">Oncorhynchus</Emphasis>) <Emphasis Type="Italic">mykiss</Emphasis> from Kamchatka

Using AP-PCR, the genome of Kamchatka mykiss (Parasalmo (O.) mykiss) was examined. Polymorphic fragments, implying geographic differences among the samples, were selected, cloned, and sequenced. Based on these sequences, longer, specific SCAR primers were selected and constructed. Using the BLAST software program, the sequences were analyzed for analogy to those from the GenBank database. It seemed likely that all sequences obtained belonged to earlier unexamined repeated sequences, variable in the populations of the species of interest. A total of seven SCAR markers, characterized by population-significant variability of the DNA products in Kamchatka geographic group of rainbow trout were constructed. These markers can be used for further investigation of the species Parasalmo (O.) mykiss. The SCAR marker sequences were deposited in GenBank under the accession numbers EU805500 to EU805506.     

Biological and Structural Basis for Aha1 Regulation of Hsp90 ATPase Activity in Maintaining Proteostasis in the Human Disease Cystic Fibrosis

The activator of Hsp90 ATPase 1, Aha1, has been shown to participate in the Hsp90 chaperone cycle by stimulating the low intrinsic ATPase activity of Hsp90. To elucidate the structural basis for ATPase stimulation of human Hsp90 by human Aha1, we have developed novel mass spectrometry approaches that demonstrate that the N- and C-terminal domains of Aha1 cooperatively bind across the dimer interface of Hsp90 to modulate the ATP hydrolysis cycle and client activity in vivo. Mutations in both the N- and C-terminal domains of Aha1 impair its ability to bind Hsp90 and stimulate its ATPase activity in vitro and impair in vivo the ability of the Hsp90 system to modulate the folding and trafficking of wild-type and variant (ΔF508) cystic fibrosis transmembrane conductance regulator (CFTR) responsible for the inherited disease cystic fibrosis (CF). We now propose a general model for the role of Aha1 in the Hsp90 ATPase cycle in proteostasis whereby Aha1 regulates the dwell time of Hsp90 with client. We suggest that Aha1 activity integrates chaperone function with client folding energetics by modulating ATPase sensitive N-terminal dimer structural transitions, thereby protecting transient folding intermediates in vivo that could contribute to protein misfolding systems disorders such as CF when destabilized.     

Volatile metabolic profiles of cell suspension cultures of Lavandula vera,Nicotiana tabacum and Helianthus annuus,cultivated under different regimes

Cell suspension cultures of Lavandula vera (Lamiaceae), Nicotiana tabacum (Solanaceae), and Helianthus annuus (Asteraceae) were cultivated in three different ways: in shake flasks both as free suspensions and in two‐phase systems (in the presence of Amberlite XAD‐4 resin as a second phase), as well as in 3‐L stirred tank reactor, and their volatile metabolic profiles were studied using GC‐MS. A number of compounds, some of them having allelochemical and biological activities, were identified in all the three cell suspension cultures under study. Also the presence of some compounds, unusual for the intact plants, was observed. It was found that the cultivation mode strongly influences the production and the transport (secretion into the culture medium) of the low‐molecular‐mass volatile metabolites. Principal component analyses of 12 common hydrocarbons showed discrimination between the different cultivation modes (shake flasks and two‐phase systems cultivation) by first principal component (PC1) and second principal component (PC2).     

The lipid status of young of the year mykiss <Emphasis Type="Italic">Parasalmo mykiss</Emphasis> and coho salmon <Emphasis Type="Italic">Oncorhynchus kisutch</Emphasis>

The young of the year mykiss Parasalmo mykiss and coho salmon Oncorhynchus kisutch which perform downstream migration and which stay in the coastal zone during the period of primary dispersion represent different phenotypic groups. They differ in weight, length, and lipid status. Such differentiation is a factor controlling the formation of intrapopulation diversity and of the life strategy of fish. It may determine the timing of smoltification in the future and, further on, of the return for spawning. There were found some analogies and differences in characteristics of lipid metabolism in the investigated species. The content of total lipids decreases by autumn in underyearlings of both species. Furthermore, changes in the content of particular lipid fractions are multidirectional and various scaled, seemingly being related to physiological preparation for the wintering.     

Migrations and resources of sterlet <Emphasis Type="Italic">Acipenser ruthenus</Emphasis> (Acipenseridae) from the lower reaches of the Volga River

Based on long-term materials, spawning, postspawning, and downstream migrations of the Lower Volga sterlet Acipenser ruthenus were studied. The dates, extent, pattern (two-step and one-step) and main parameters of the spawning and postspawning migrations of the previously separated three populations of the Lower Volga starlet—Volgograd and eastern and western delta ones were established. The main differences of the downstream migration of this potanadromous species from that of anadromous species of acipenserids were revealed. It was found that, after downstream migration, juveniles of sterlet form a continuous chain of aggregations from the dam of the Volgograd Hydraulic Power System to the Caspian Sea. Each link of this chain acts as a center of formation of local groups of sterlet that are components of the distinguished populations. It is shown that the observed distribution of sterlet in the lower reaches of the Volga is determined by the location of the spawning grounds of individual populations and the extent of downstream migrations of prolarvae and larvae. The total extent of migrations of sterlet is small (it does not exceed 250 km), which is a cause of the relative isolation of the previously distinguished populations. The stocks of Volgograd sterlet are exhausted at the present time; the recovery of its stock is possible, first of all, at the expense of a decrease in illegal fishing. The resources of the eastern and western delta populations of sterlet are in a satisfactory condition.     

Ecological analogies in the Pacific lamprey <Emphasis Type="Italic">Lethenteron camtschaticum</Emphasis> and the mykiss <Emphasis Type="Italic">Parasalmo mykiss</Emphasis> in Kamchatka

Ecological analogies between the Pacific lamprey Lethenteron camtschaticum and various species of salmonids (Salmonidae) are noted. Close analogies are found with the mykiss Parasalmo mykiss. The lamprey and mykiss are characterized by spawning in spring. In their populations there are specimens with anadromous and riverine life strategies. The mechanism of formation of life strategies seems to be similar in both species. The major role belongs to the trophic factor determining the level of energy resources necessary for maturation. Such analogies result from epigenetic changes in principal ecological parameters and are formed under the influence of similar environmental factors.