Comparative study of D-glyceraldehyde-3-phosphate dehydrogenase from frog and pike skeletal muscles]

The purified preparations of glyceraldehyde-3-phosphate dehydrogenase isolated from frog and pike skeletal muscles were found homogenous under polyacrylamide gel electrophoresis. Their amino acid composition is similar to that of glyceraldehyde-3-phosphate dehydrogenase from other animal species. The interaction kinetics for frog and pike glyceraldehyde-3-phosphate dehydrogenase SH-groups with 5,5'-dithio-bis-(2-nitrobenzoate) (DTNB) were studied. A negative correlation between the thermal stability of the enzyme preparations from pig, pike, lamprey and frog muscles and the reactivity of their SH-groups with respect to DTNB was observed. NAD at saturating concentrations was found to protect the enzyme from lower vertebrates muscles against thermal inactivation in a lesser degree than does the pig muscle enzyme. The weaker protective effect of NAD was observed for lamprey and frog enzyme preparations, which are characterized by a low SH-group reaction ability. Frog and pike apoenzymes are considerably more resistant to trypsin proteolysis than the pig apoenzyme.     

Evolution of mechanisms of Ca2+ -signaling. Significance of Ca2+-messenger systems during transition of organisms to multicellularity

The review considers Ca2+ -messenger systems in primitive multicellulars (sponges and hydrozoa organisms). Analysis is performed of Ca2+ participation in regulation of early development of the organisms, their mobility, metamorphosis, chemoreception, and some other functions.     

Frequency of occurrence of Hepatitis C virus markers and risk factors among hospital personnel in the Novosibirsk region

The occurrence of markers, the genotypic variety of isolates and the profile of risk factors with respect to viral hepatitis C among 629 employees of the Regional Clinical Hospital (RCH) in Novosibirsk and 1,020 employees of the Central District Hospital (CDH) in Iskitim were studied in a cross-sectional investigation. The occurrence of hepatitis C virus (HCV) markers was 5.1% in RCH and 2.2% in CDH. Among the risk factors in the population under study were: the medical history of blood transfusions (TF) with 0 TF, anti-HCV = 2.3%; 1 TF, = 5.7% > 1 TF, = 13.5% (p < 0.001); general anesthesia (GA) with < or = 2 GA, anti-HCV = 2.8%; > 2 GA, = 7.8% (p = 0.002); surgical interventions (SU) with 0 SU, = 1.9%; > 0 SU, = 4.3% (p = 0.012); the intravenous use of drugs (OR = 31.8); age (< or = 25 years, anti-HCV IgG = 8.6% > 25 years, = 4.5%); the number of partners of the opposite sex < or = 4 partners, = 2.4%; > 4 partners, = 6.9%; p < 0.001). The probable risk factors at a working place (pricks and cuts, contamination of mucous membranes with blood and other biological fluids, etc.) proved to be faintly related with the status of HBV infection. HBV isolates detected in the examined persons (35 examinees) were distributed by genotypes as follows: 60% of subtype 1b, 28.6% of subtype 2a/2c, 11.4% of subtype 3a. HBV of genotype 1a was not detected in the examined specimens, while the detection rate of genotype 2a/2c was considerably greater than in specimens obtained in the European and Asian parts of Russia (according to the data reported earlier).     

Detection of lipid–protein microdomains (rafts) and investigation of their functional role in the chloroplast membranes of halophytes

To study the characteristics of the structure and the functional role of chloroplast membranes of halophytes with different salt tolerance strategy, raft structures were isolated. Lipid analysis data provided evidence for the presence of rafts in the chloroplast membranes. The discovered significant differences in the content of raft-forming lipids in different halophytes suggest a relationship between the functions of rafts and the mechanisms of salt tolerance in plants.     

Slow calcium waves in cultured postnatal rat skeletal myocytes

A variety of active agents increasing [Ca2+]i in cultivated skeletal myocytes have been investigated. It was shown that, out of the agents such as noradrenaline, carbacholine, caffeine, cyclopiazonic acid, and potassium solution, only the last caused the formation of slow calcium waves in skeletal myocytes. These waves propagated not only near the location of the cell nucleus but also along the whole length of myocytes. It is supposed that this wave process can be related to the modulation of excitation-relaxation processes in skeletal muscles.     

Trafficking of yellow-fluorescent-protein-tagged mu1 subunit of clathrin adaptor AP-1 complex in living cells

Clathrin adaptor protein AP-1 complex is thought to function in forming clathrin-coated vesicles at the trans -Golgi network (TGN) and mediating transport of cargo between the TGN and endosomes. To study trafficking of AP-1 in living cells, yellow fluorescent protein (YFP) was inserted in the middle of µ1 A subunit of AP-1. When expressed in a tetracycline-dependent manner in HeLa cells, YFP-µ1 was efficiently incorporated into the AP-1 complex, replacing endogenous µ1 in most of cellular AP-1. Time-lapse imaging revealed that YFP-µ1/AP-1 departs from TGN as isolated vesicles and spherical structures, or varicosities, associated with fine tubular processes. Typically, several vesicles or varicosities were seen moving sequentially along the same 'tracks' from TGN to cell periphery. These data suggest that AP-1 may function after formation of Golgi transport intermediates in facilitating their intracellular movement. Mutagenesis of YFP-µ1 determined that the structural requirements for its binding to tyrosine-containing sequence motifs are similar to those previously defined in µ2 subunit of AP-2. Moreover, the carboxyl-terminal half of µ2 could replace the corresponding fragment of µ1 without loss of the ability of the resulting µ1-YFP-µ2 chimeric protein to incorporate into AP-1 and bind tyrosine-containing motifs. Mutations that abolish binding capacity for tyrosine motifs did not mistarget AP-1 in the cell, suggesting that AP-1 interactions with this type of sorting signals are not essential for membrane docking of AP-1 at the TGN. Altogether, this study demonstrates that YFP-tagged µ1 protein can serve as a useful tool for visualizing the dynamics of AP-1 in living cells and for the structure-function analysis of µ1–cargo interactions.