Selective effect of the duration of the critical temperature period on some allozyme loci of Atlantic salmon Salmo salar L. (Salmonidae)

Genetic structure of juvenile fish from the populations of the Atlantic salmon Salmo salar inhabiting the rivers of Murmansk oblast, Arkhangelsk oblast, and Karelia, as well as of juveniles from hatcheries was examined at five allozymic loci: aspartate aminotransferase (AAT-4*), isocitrate dehydrogenase (IDHP-3*), iditol dehydrogenase (IDDH-2*), esterase D (ESTD*), and malic enzyme (MEP-2*). High genetic differentiation of both natural and “hatchery” juvenile fish was revealed. It was demonstrated that the gene pool of juveniles at three of the five loci tested was to a considerable degree formed by natural selection. In this case, the role of limiting factor was played by the duration of critical temperature regime in the rivers. The differentiation factors for juveniles from nature were not established, however, their clusterization pattern pointed to a possible role of natural selection in this process.     

Contractile properties, transversal stiffness and cytoskeletal protein content in Mongolian gerbils soleus fibers under long-term hindlimb suspension

Structural and functional changes in Mongolian gerbil soleus fibers were analyzed after a 31-day hindlimb suspension. Contractile properties of muscle fibers were studied by means of tensometry; the transversal stiffness of different parts of the contractile apparatus was measured by atomic force microscopy, resting calcium level was estimated by fluorescence microscopy by using Fluo-4-AM; cytoskeletal protein content was determined by western blotting. It was shown that after gravitational unloading the maximal force of contraction and specific tension of fiber were significantly reduced, as well as calcium sensitivity actually lowered. At the same time, the transversal stiffness of Z-disk in the relaxed and activated state was decreased significantly compared to the control group. Desmin content was at the control level, but alpha-actinin-2, main structural protein of Z-disk, became considerably less after a 31-day hindlimb suspension. Besides, resting calcium level remained at control values during the simulated gravitational unloading. The data suggest that Z-disk destruction, as a result of alpha-actinin-2 content reduction, leads to changes in the lattice spacing and decreases contractile properties.     

The Extracellular Protein of Luteococcus japonicus subsp. casei Reactivates Cells Inactivated by UV Irradiation or Heat Shock

The culture liquid of Luteococcus japonicus subsp. casei was found to be able to reactivate cells of this bacterium inactivated by UV irradiation or heat shock. The antistress activity of the culture liquid was due to the presence of an extracellular exometabolite of a protein nature with a molecular mass of more than 10 kDa. When the bacterium was grown in a nutrient broth or glucose-containing mineral medium, the antistress protein was secreted by cells in the logarithmic growth phase. The reactivating effect of the antistress protein was inversely proportional to the survival rate of stressed cells.     

The use of commercial immunoenzyme kits for the diagnosis of toxoplasmosis

The results of comparative study of sera obtained from donors and from several groups of patients with suspected toxoplasmosis are presented. The study has been carried out with the use of commercial enzyme immunoassay (EIA) kits: Toxoplasma gondii IgG EIA and Toxoplasma gondii IgM EIA manufactured by Labsystems (Finland), Sevatest ELISA IgG Toxo Micro I manufactured by Sevac (Czechoslovakia). Statistical processing of the results has confirmed the identity of these kits. The necessity of using evaluation criteria (the separation point, the scale for the interpretation of results) when working with the Sevac kits is emphasized. Comparative evaluation of antibody profiles in the sera under test suggests that the titer less than 1:1600 should be regarded as the separation point for these kits. IgM antibodies to T. gondii have been found only in 22% of patients with high titers of IgG antibodies.     

Stromule-like protrusions of plastid membrane envelope in root cells

The work presents the results of the electron-microscopy visualization of stromule-like protrusions of plastid membrane envelope in root cells. Cases of the appearance of a long, narrow protrusion of the outer membrane, in which the shorter protrusion of the plastid envelope inner membrane was located, are discussed. The possible role of cytoskeleton and plastoskeleton in formation of outer and inner protrusions, respectively, is considered. It is concluded that items of the structure and functions of stromules in plant cells are to be considered to be the same as the structure and functions of the intracavity space of endoplasmic reticulum.     

Seasonal and circadian fluctuations in blood biochemical indicators in mice in natural conditions and exposed to constant light]

The fluctuations of activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and those of the levels of protein, glucose, cholesterol, bilirubin, creatinine, blood urea nitrogen, K+, Cl-, Na+ in blood plasma of mice in natural conditions (NC) and exposed to constant light (CL) were studied in different seasons of the year (in January, April, July, October) on days 18, 24, 6 (at 12 o'clock). Most indices both in NC and CL animals had seasonal rhythm similar for each of them. This proves a primary effect of environmental geoclimatic factors of formation of circadian periodicals as compared to desynchronization in constant light revealed by Kosinor analysis in winter (acrophase from 14.16 till 16.32 o'clock) and autumn (acrophase from 23.03 til 4.40 o'clock). During the same seasons one can observe the maximum desynchronization influences of constant light, which leads to abrupt falling (to the 10-fold and more) of the fluctuations amplitude and in some cases to stabilization of circadian rhythm.     

A Rare Case of Permanent Introgressive Hybridization in Char of the Genus Salvelinus (Salmonidae: Salmoniformes) in the Utkholok River,Western Kamchatka

Russian Journal of Marine Biology - Hybrids between the whitespotted char Salvelinus leucomaenis and the northern Dolly Varden S. malma malma have been found to regularly occur and exist...     

Selective labeling of barstar in a T7 polymerase system by 15N-isotopes

It has been shown that the use of a special growth medium enriched with amino acids and an inhibitor of aminotransferases alpha-aminooxyacetic acid makes possible the selectivity of labeling of barstar with 15N-leucine and 15N-tryptophan. The system of selective labeling, which was previously optimized with respect to the time of introducing the label relative to the time of introducing the inductor IPTG and the inhibitor of cell polymerase rifampicin, was substantially refined by the use of the transamination inhibitor. The inhibition of aminotransferases enables one to completely eliminate the redistribution of the isotope, which is a necessary step in NMR studies even if the strongly metabolizable 15N-leucine is used. The suppression of the redistribution of the isotope by alpha-aminooxyacetic acid is a successful approach to preparation of any selectively labeled proteins in the T7 polymerase system.     

Reactivating effect of Escherichia coli exometabolites on UV-irradiated cells

Wild-type and mutant (AB 1157 and K-12) strains of Escherichia coli were shown to synthesize the logarithmic growth phase, exometabolites reactivating UV-irradiated cells of producer strains. The exometabolites of the strain K-12 were of protein nature and had a molecular weight of no more than 10 kDa. The reactivating activity of these exometabolites was inversely related to bacterial survival and slightly increased under the influence of stress factors. The reactivating factor of Luteococcus casei had a cross-reactivating and protective effect on UV-irradiated cells of E. coli strain K-12. Due to activation of the reactivating factor after UV irradiation and heating, the cross-protective effect increased more than threefold. The reactivating effect remained unchanged under these conditions. The protein exometabolites of E. coli did not induce cross-stress response in L. casei.