Some Data on Reproductive Biology of Spotted Ghoul Inimicus sinensis (Synanceiidae)

Journal of Ichthyology - Gonadal structure, cytological condition of oocytes, ultrastructure of egg envelope, and spermatozoa morphology are studied in the individuals of Inimicus sinensis...     

Winter Fish Distribution in the Riverbed Depression in the Urtysh River

Journal of Ichthyology - Winter fish distribution is investigated by means of computerized hydroacoustic complexes in the largest riverbed depression in the Irtysh. Fish aggregations whose...     

Change of Rheoreaction and Concentration of Thyroid Hormones in Blood of Juvenile Rainbow Trout Oncorhynchus mykiss during Starvation

Journal of Ichthyology - Rheoreaction and concentration of thyroid hormones in blood of juvenile rainbow trout Oncorhynchus mykiss is studied during starvation (12 days). It is found that...     

Regulation of crystalline lens aldose reductase activity. Nonhyperbolic oxidation kinetics of NADPH by glucose

A homogeneous aldose reductase was isolated from bovine eye lens tissue by using affinity chromatography on blue agarose. A kinetic analysis of the initial rates of NADPH oxidation at 0.5-100 mM glucose and at 1.2-10 microM NADPH was carried out. The Line-weaver-Burk plots for glucose concentration were nonlinear at fixed concentrations of NADPH and linear at fixed concentrations of glucose. It was shown that the experimental plots reflect the mechanisms, in which substrate regulation of enzyme activity is effectuated by glucose binding to the regulatory site or is due to the shift of the equilibrium between the isomeric forms of aldose reductase.     

Evenly tritium labeled peptides in study of peptide in vivo and in vitro biodegradation

Biologically active peptides evenly labeled with tritium were used for studying the in vitro and in vivo biodegradation of the peptides. Tritium-labeled peptides with a specific radioactivity of 50–150 Ci/mmol were obtained by high temperature solid phase catalytic isotope exchange (HSCIE) with spillover tritium. The distribution of the isotope label among all amino acid residues of these peptides allows the simultaneous determination of practically all possible products of their enzymatic hydrolysis. The developed analytical method includes extraction of tritium-labeled peptides from organism tissues and chromatographic isolation of individual labeled peptides from the mixture of degradation products. The concentrations of a peptide under study and the products of its biodegradation were calculated from the results of liquid scintillation counting. This approach was used for studying the pathways of biodegradation of the heptapeptide TKPRPGP (Selank) and the tripeptide PGP in blood plasma. The pharmacokinetics of Selank, an anxiolytic peptide, was also studied in brain tissues using the intranasal in vivo administration of this peptide. The concentrations of labeled peptides were determined, and the pentapeptide TKPRP, tripeptide TKP, and dipeptides RP and GP were shown to be the major products of Selank biodegradation. The study of the biodegradation of the heptapeptide MEHFPGP (Semax) in the presence of nerve cells showed that the major products of its biodegradation are the pentapeptide HFPGP and tripeptide PGP. The enkephalinase activity of blood plasma was studied with the use of evenly tritium labeled [Leu]enkephalin. A high inhibitory effect of Semax on blood plasma enkephalinases was shown to arise from its action on aminopeptidases. The method, based on the use of evenly tritium-labeled peptides, allows the determination of peptide concentrations and the activity of enzymes involved in their degradation on a μg scale of biological samples both in vitro and in vivo.