Vertical distribution of zooplankton in the frontal zone of the Gulf Stream and Labrador Current

Zooplankton data collected during September 1995 in the NorthWest Atlantic at 4139'N, 4958'W (the location of the siteof the ‘Titanic’ wreck) were analysed. The regioninvestigated was characterized by a very sharp frontal zonebetween the Gulf Stream and the main stream of the LabradorCurrent. The total plankton biomass in the water column wasvery high. The macroplankton biomass values below the 600 mlayer were significantly higher as compared with the similarvalues measured before in other productive boreal regions ofthe Atlantic and Pacific oceans. A lot of dead mesoplanktonanimals occurred in the deep layers. The reason was that thecold-water mesoplankton advected by the Labrador Current diedoff intensively within the deep layers of the frontal zone andwere used as a food resource by the macroplankton carnivoresand scavengers that were very abundant there.     

Modulation of ornithine decarboxylase activity in the normal and regenerating rat liver by different doses of hydra peptide morphogen

The authors studied the anabolic effect of peptide morphogen of the hydra undecapeptide on normal and regenerating rat liver. Ornithine decarboxylase (EC 4.1.1.17) activity served as a marker. Intraperitoneal injection of the peptide into intact animals stimulated ornithine decarboxylase activity in a dose-dependent manner. In partially hepatectomized rats the peptide stimulated ornithine decarboxylase activity in the dose of 20 micrograms/kg body weight while greater doses inhibited the enzyme activity.     

Effect of dehydrocorrine-cobalt complex on mitochondria

The effects of the decamethyloctadehydrocorrine-cobalt complex (Co-C) on respiration and the ATP-synthetase activity of rat liver mitochondria were investigated. The Co-C complex was found to be an effective shunt of the respiratory chain. It accepts electrons from ubiquinone and donates them directly to O2. The Co-C complex inhibits the ATPase and ATP-synthetase activities of mitochondria.     

Influence of dissolved gases on highly diluted aqueous media

In the experiments on redox potential measurement for a series of identical samples of purified and presettled water it was found that the response to ultraviolet irradiation varies appreciably within a few days after treatment, including stepwise changes. In a few hours after exposure, leading to a higher content of reactive oxygen species as compared with the equilibrium values, long-term changes including variations in redox potential and optical system parameters are recorded in water and diluted aqueous media. We propose a heuristic organization model of the water-gas system with an increased content of reactive oxygen species.     

Determination of antithrombocyte antibodies in the blood serum of patients with idiopathic thrombocytopenic purpura by an immunoenzyme method

Enzyme-linked immunosorbent assay (ELISA) was developed for determination of serum antiplatelet antibodies. Platelets obtained from healthy donors of blood group 0(1) were washed off plasma and sedimented on the bottom of microtest wells. After washing off unattached platelets and blocking of plastic with albumin platelets were incubated with sera under investigation and binding of serum antibodies was detected using antihuman immunoglobulin antibodies conjugated with peroxidase. Ten patients with idiopathic thrombocytopenic purpura (ITP). 1 patient with systemic lupus erythematosus. 1 patient with red blood cell aplasia and 9 healthy donors (negative control) were studied by ELISA. Serum antibodies which effectively bound to platelets were detected in 5 patients with ITP, in patient with lupus erythematosus and in patient with red blood cell aplasia.     

Purification and properties of NADP-dependent isocitrate dehydrogenase from the bovine adrenal cortex

NADP-dependent isocitrate dehydrogenase (EC 1.1.42) was isolated and 430 times purified from the hyaloplasm fraction of bull adrenal cortex using fractionation by ammonium sulphate and acetone, heat treatment, chromatography on DEAE-Sephadex A-50, gel-filtration on Sephadex G-200 and affinity chromatography on 2',5'-ADP-sepharose 4B. The specific activity of homogeneous enzyme is 60 units per 1 mg of protein at 30 degrees C, yield--34%, pH optimum--8.0, molecular weight, determined by gel filtration on Sephadex G-200, is 96 kDa. The preparation electrophoresis in PAAG in the presence of DS-Na reveals one protein fraction with the mobility corresponding to that of protein having molecular weight of 46 kDa. The data obtained evidence for a dimer structure of the isocitrate dehydrogenase molecule from bull adrenals.     

Kinetic properties of NADP-specific isocitrate dehydrogenase from bovine adrenals

At low concentrations of Mg2+ or Mn2+ the reaction catalyzed by isocitrate dehydrogenase from bovine adrenal cortex proceeds with a lag period which disappears as a result of the enzyme saturation with Mn2+ or Mg2+. The nu o versus D,L-isocitrate concentration curve is non-hyperbolic, which may be interpreted either by the presence of two active sites with different affinity for the substrate (K'mapp = 2.3 and 63 microM) within the enzyme molecule or by the "negative" cooperativity of these sites. The apparent Km value for NADP lies within the range of 3.6-9 microM. High concentrations of NADP inhibit isocitrate dehydrogenase (Ki = 1.3 mM). NADP.H inhibits the enzyme in a mixed manner with respect to NADP (Ki = 0.32 mM). In the presence of NADP.H the curve nu o dependence on NADP concentration shows a "negative" cooperativity between NADP binding sites. The reverse enzyme-catalyzed reaction of reductive carboxylation of 2-oxoglutarate does not exhibit any significant deviations from the Michaelis-Menten kinetics. The Km value for 2-oxoglutarate is 120 microM, while that for NADP.H is 10 microM.     

Characteristics of kinetics of the enzymatic oxoglutarate dehydrogenase reaction in a system with 2,6-dichlorophenolindophenol

The 2-oxoglutarate: 2,6-dichlorophenolindophenol (DCPIP)--oxidoreductase reaction catalyzed by the oxoglutarate dehydrogenase complex from bovine adrenal glands corresponds to the kinetic mechanism of a "ping-pong" type. There are signs of positive cooperativity of the oxoglutarate dehydrogenase interaction with the substrate and negative cooperativity of that with the electron acceptor. The half-maximal rate of the model reaction is provided by 0.01 mM concentrations of 2-oxoglutarate and DCPIP. The exceeding of the DCPIP optimum concentration (0.1 mM) results in the enzyme inhibition.     

Isolation and characteristics of antibodies against synthetic fragments of oncoproteins. II. Antiserum against the transforming protein pp60src of Rous sarcoma virus

To generate the antibodies to the transforming protein of Rous sarcoma virus (RSV) pp60src, rabbits were immunized with the peptide, corresponding to 415-421 sequence of pp60src. These antibodies immunoprecipitate pp60src in RSV-transformed chicken and mammalian cells, and also some proteins (45, 85 and 120 kDa), which could be autophosphorylated in vitro. It was shown that 415-421 sequence of pp60src is not recognized by the antibodies to pp60src from RSV-induced tumour bearing rabbits (TBR serum). In contrast to TBR serum, antibodies, generated against synthetic peptide, corresponding 415-421 sequence of pp60src couldn't be phosphorylated in vitro, when [gamma-32P]ATP is added to the immune complex. The antipeptide antibodies, bound to pp60src did not block phosphorylation of TBR immunoglobulins, added to this immune complex. Hence, 415-421 sequence of pp60src RSV containing the major tyrosine phosphorylation site does not take part in the kinase reaction in vitro.     

Three adenine nucleotide binding sites in F1-F0 mitochondrial ATPase as revealed by presteady-state and steady-state kinetics of ATP hydrolysis. Evidence for two inhibitory ADP-specific noncatalytic sites

Preincubation of submitochondrial particles with ADP in the presence of Mg2+ results in the complete inhibition of ATPase which is slowly reactivated in the assay mixture containing ATP and the ATP regenerating system. Significantly, the rate of activation increases as the concentration of ADP in the preincubation mixture rises from 1 microM to 20 microM and reaches a constant value at higher ADP concentrations. The first-order rate constant for the activation process in the assay mixture is ATP-dependent at any level of inhibitory ADP. The data obtained strongly suggest that two ADP-specific inhibitory sites and one ATP-specific hydrolytic site are present in F1-F0 ATPase. Taking into account the (3 alpha.3 beta).gamma.delta.epsilon structure of F1, it is concluded that the synchronous discharge of ADP from two inhibitory sites during the activation occurs after ATP binds to the ATPase catalytic site.