Reproductive Strategies and the Origin of Parapatric and Sympatric Forms of Arctic Charr Salvelinus alpinus (Salmonidae) in the System of Lakes Bol’shoe Leprindo and Maloe Leprindo (Northern Transbaikalia)

Journal of Ichthyology - In the system of lakes Bol’shoe Leprindo and Maloe Leprindo (Lena basin, Transbaikalia), spawning of two isolated populations of the dwarf form of Arctic charr...     

Estimating Competition in Cladocerans Using Data on Dynamics of Clutch Size and Population Density

Negative correlations between clutch size and population density are proposed to be considered as indices of intra- and interspecific competition in cladocerans if they are revealed while analyzing population dynamics and clutch size and time lags are taken into account. The proper correlation analysis of summer populations of Diaphanosoma brachyurum, Bosmina coregoni, Daphnia cucullata and D. galeata from mesotrophic Lake Glubokoye (Moscow Region) in 1975, 1978, and 1979 indicates the important role of competition of both types for the community studied. High niche overlap in food and space in the four populations was also observed.     

Actomyosin preparations obtained from a skeletal muscle tumor of low differentiation using the traditional methods of muscle biochemistry

Tumor actomysion preparations isolated by three different extracting solutions are very similar in composition. A characteristic feature of the preparations obtained is a very rapid presumably proteolytic degradation of their components. It is shown that the major polypeptides of freshly prepared samples are not products of proteolysis. The major protein components of these preparations are identified.     

Study of "group" expression of mRNA of the ion transporters ATP1B1, NHE1 and NKCC1, beta-actin, glycerophosphosphate dehydrogenase, proteins regulating proliferation and apoptosis of p53, Bcl-2, IL-2 and hSGK kinase at the prereplicative stage of human lymphocyte activation

Previously, we found no segregation in F2 obtained from crosses between two Dileptus anser clones differing (under the same culture conditions) in their serotypes, i.e. in their immobilization antigens (i-antigens); indeed, all the F2 clones had mixed, i.e. hybrid serotype, being immobilized simultaneously with both immune sera developed against either parental clone (Uspenskaya, Yudin, 2000). Presently, experiments were carried out to see if this unusual phenotype would be re-expressed after a temporary switching off. To switch off both expressed i-antigens, serotype transformation was induced in the F2 clones by shifting the culture temperature from 25 to 17 degrees C. Two weeks later, when the clones returned to the initial temperature conditions, each of them was seen to re-express both parental i-antigens. This result is discussed with reference to the role of i-antigens in regulation of their own expression as has been suggested by some authors.     

Using inter-SINE-PCR to study mammalian phylogeny

Results of the use of the fingerprinting method related to short interspersed elements (SINEs), inter-SINE-PCR, in the study of phylogenetic and taxonomic relationship in mammals from orders Chiroptera (family Vespertilionidae) and Lipotyphla (family Erinaceidae) are reported. The inter-SINE-PCR method is based on the amplification of fragments situated between copies of SINEs, which are short retroposons spaced 100 to 1000 bp apart. Specifically selected primers were used, which are complementary to consensus sequences of two short retroposons: the mammalian interspersed repeat (MIR), which is typical of all mammals and some other vertebrates, was used in the cases of bats and Erinaceidae, and the ERI-1 element recently isolated from the genome of the Daurian hedgehog was used in the case of Erinaceidae. The results support the current view on phylogenetic relationship between hedgehogs belonging to genera Erinaceus, Hemiechinus, and Paraechinus (but not the genus Atelerix). In bats, the phylogenetic reconstruction revealed a statistically valid topology only at lower taxonomic levels, whereas the topology for the genus and supragenus ranks was unresolved and fan-shaped. The benefits and limitations of the inter-SINE-PCR method are discussed.     

Evidence of a new type of protein-protein interaction: desensitized actomyosin blocks Ca(2+)-sensitivity of the natural one. A possible model for an intracellular signalling system related to actin filaments

Actin filaments are certainly believed to function as an intracellular signalling system; however, this is not confirmed by direct evidence. We used a two-layer actomyosin gel with a concentration gradient of the troponin-tropomyosin complex (TT-complex, Ca(2+)-sensitive system) between the two layers. To prepare one layer of the system, natural actomyosin (nAM) rich in TT-complex was used. To prepare the second layer, we used desensitized actomyosin (dAM) without the complex. All experimental studies were made in medium with a low ionic strength. Two phenomena were observed: (1) dAM blocks Ca(2+)-sensitivity of nAM when the dAM weight portion in the system (as well as in mixed nAM + dAM suspension) reaches 40% and more; further increase of the dAM portion does not affect the Ca(2+)-sensitivity; (2) it was electrophoretically shown that a rapid diffusion of the TT-complex from nAM gel into the dAM gel took place. The apparent diffusion coefficient for the TT-complex in dAM gel is about (1-4).10(-4) cm2/sec, i.e. three orders higher than the same values for protein diffusion in water.     

Effect of chronic treatment with Rosiglitazone on Leydig cell steroidogenesis in rats: <Emphasis Type="Italic">In vivo</Emphasis> and <Emphasis Type="Italic">ex vivo</Emphasis> studies

Background  

The present study was designed to examine the effect of chronic treatment with rosiglitazone - thiazolidinedione used in the treatment of type 2 diabetes mellitus for its insulin sensitizing effects - on the Leydig cell steroidogenic capacity and expression of the steroidogenic acute regulatory protein (StAR) and cholesterol side-chain cleavage enzyme (P450scc) in normal adult rats.     

Time evolution of the ion temperature in the T-10 tokamak during simultaneous pellet injection and electron-cyclotron resonance heating

Results are presented from studies of the time evolution of the ion temperature in the T-10 tokamak in the course of injection of several (up to five) deuterium pellets into a deuterium plasma the electron component of which is heated at the second harmonic of the electron gyrofrequency. It is shown that, at an electron cyclotron heating power of 900 kW, the injection of five pellets is accompanied by an increase in the ion temperature to 1200 keV, which is a record value for T-10. It is noted that energy exchange between the electron and ion components in these experiments is a purely classical, Coulomb process.