Adaptive thermoregulatory reactions of the rabbit fetus at the end of the intrauterine development

The data of permanent simultaneous registration of electrocardiogram, rectal & brown adipose tissue temperatures of the rabbit foetus have been obtained in chronic experiments. The haemodynamic shift in intensity of maternal-placental and foeto-placental blood flow (by female trental injection) led to a decrease in the foetus rectal temperature (0.33 +/- 0.09 degree C in intact foetus and 0.58 +/- 0.27 degree C in retarded foetus, p < 0.05). Both foetuses reacted by rectal temperature decrease (0.65 +/- 0.28 & 0.68 +/- 0.31 degree C, respectively) during immobilisation (by foetus arduan injection). Thus in both series of experimental cooling of foetus, brown fat activation was similar in intact foetus (approximately 53%), but did not change in growth retardation foetus--as a result of its tissue functional immaturity, probably.     

Complete nucleotide sequences of bovine alpha S2- and beta-casein cDNAs: comparisons with related sequences in other species

The nucleotide sequences corresponding to bovine alpha S2- and beta- casein mRNAs have been determined by cDNA analysis. Both sequences appear to be complete at their 5' ends. The nucleotide sequence of alpha S2-casein, when compared with the corresponding cavine A sequence, helps to define the boundaries of a large amino acid repeat (approximately 80 residues) whereas comparisons with the nucleotide sequences of rat gamma- and mouse epsilon-casein mRNAs also reveal extensive sequence similarities. An alignment of these four sequences shows that the divergence of their translated regions has been characterized by the duplication and deletion of discrete segments of sequence that probably correspond to exons. A high degree of nucleotide substitution is also found when the four sequences are compared, except for well-conserved leader-peptide and phosphorylation-site sequences and, to a lesser extent, the 5'-untranslated regions. Similar comparison of the bovine and rat beta-caseins shows that their divergence has involved a high rate of nucleotide substitution but that no major insertions or deletions of sequence have occurred. The several splice sites that have veen defined in the rat beta-casein gene are likely to have been conserved in the bovine. The contrasting evolutionary histories of the alpha- and beta-casein coding sequences correlate with the distinctive functions of these proteins in the casein micelle system in milk.      

Population genetics of taiga hunters and reindeer breeders in central Siberia. The biochemical markers of genes Hp, Tf, Gc, A1b, GLO1, PGM1, AcP and EsD

Biochemical markers of gene systems Alb, Tf, Gc, Hp, GLO1, PGM1, EsD, AcP were analysed in the native population of Evenc national region. It is shown that native population of Central Siberia, in spite of its mongoloid racial type, posseses the complex of gene frequencies for protein loci studied which is not typical for mongoloids. The complex may be called "central-siberian" and its origin may be connected with the process of adaptation to environment of the Central Siberian geographical region. The system of gene markers analysed may be considered as a sensitive one in the studies of processes of gene adaptation to the local environmental factors and, in this connection, being perspective in these studies among native population of Siberia.     

An experimental study of the safety of a chemical monovalent tableted cholera vaccine in enteral administration]

The safety of experimental chemical cholera monovalent vaccine in tablets, produced by the institute "Microbe" (Saratov, USSR), has been studied. The study has shown that the vaccine, administered to adult rabbits and germ-free suckling rabbits by the enteral route, retains residual toxicity, mainly due to the presence of O-antigen. One or two administrations of 1-2 human doses of this preparation to adult rabbits induce minimal structural changes admissible from the viewpoint of safety. After immunization made in two administrations immunobiological transformation develops more rapidly and is more pronounced than after immunization in a single administration.     

Cooperative mechanism of phosphorylation of the monomeric and dimeric forms of inorganic pyrophosphatase from baker's yeast

A comparative study of phosphorylation of native dimeric and artificial monomeric forms of inorganic pyrophosphatase and its fluoride-stabilized complex with PPi has been carried out. The maximal incorporation of Pi for the dimeric and monomeric proteins is 0.5 and 1 mole per mole of subunit, respectively. The saturation kinetic curves are suggestive of strong positive cooperative interactions. The value of the Hill coefficient (5.5) for the free dimeric enzyme drastically changes upon the active center blockage and/or transition to the monomeric enzyme. Acceleration of dephosphorylation induced by Pi in the presence of Mg2+ is observed only in the case of the dimeric protein. The data obtained indicate that phosphorylation of native dimeric pyrophosphatase occurs according to a "flip-flop" mechanism; the Pi binding in the active center exerts a strong influence on individual steps of the reaction.     

The role of Asp42 in Escherichia coli inorganic pyrophosphatase functioning.

Excess of Mg2+ ions is known to inhibit the soluble inorganic pyrophosphatases (PPases). In contrast, the mutant Escherichia coli inorganic pyrophosphatase Asp42-->Asn is three times more active than native and retains its activity at high Mg2+ concentration. In this paper, another two mutant variants with Asp42 replaced by Ala or Glu were investigated to characterize the role of Asp42 in catalysis. pH-independent kinetic parameters of MgPPi hydrolysis and the dissociation constants for the activating and inhibitory Mg2+ ions were calculated. It was shown that Mg2+ inhibition of MgPPi hydrolysis by native PPase exhibited uncompetitive kinetics under the saturating substrate concentration. All three substitutions of Asp42 lead to a sharp decrease of inhibitory Mg2+ affinity to the enzyme. These findings allow determination of the sites of inhibitory and substrate Mg2+ ions binding to PPase. Common features of these mutants allow the conclusion that the function of Asp42 is to accurately coordinate the residues implicated in the substrate and the inhibitory Mg2+ ion binding to PPase active site. Structural analysis of PPase complexed with Mg2+ compared with PPase complexed with Mn2+ and reaction products confirms this supposition.     

DNA-polycation complexes: effect of polycation structure on physico-chemical and biological properties

The purpose of the study was to investigate the influence of cationic polymer structure on the formation of DNA-polycation complexes and their transfection activity. Primary, tertiary, and quaternary polyamines with molecular masses ranging from 8000 to 200,000 were investigated. DNA-cationic polymer interaction was characterized by low gradient viscometry, dynamic light scattering, circular dichroism, UV spectrometry, flow birefringence, DNA electrophoresis, and electron microscopy. Transfection activity of the complexes was evaluated by the expression of reporter gene (beta-galactosidase) and using synthetic FITC-labelled oligonucleotides. Complex formation was found to be dependent on the structure and molecular weight of the polymer and the ionic strength of the solution. Secondary DNA structure in complexes was not disrupted, and DNA was protected from protonation. Cell lines of different origin were used for testing of transfection activity of the complexes. The sensitivity of the cells to transfection was established to be highly dependent on the cell line. DNA-polycation complexes are non-toxic according to MTT. Polyallylamine, and polydimethylaminoethylmethacrylate were found to be the most promising polycations for gene delivery. Transfection efficacy of their complexes with DNA to T-98G cells reaches up to 90-100%. It was found that optimal molecular mass of polydimethylaminoethylmethacrylate is in the range of 8000-50,000 Da.     

Age and Sex Determination in the Water Vole (<Emphasis Type="Italic">Arvicola amphibius</Emphasis>, Rodentia,Arvicolinae) Based on Measurements of the Pelvic Limb Bones

A method was developed for determining the age and sex of the water vole (Arvicola amphibius L.) based on the measurements of the pelvic limb bones. The material was obtained from captive-bred animals of a known age. By using discriminant analysis, classification functions were found for dividing the animals of the sample analyzed (n = 56) by sex and age with an accuracy equal to one year. Testing the control group (n = 34) showed that the age of 90.0% of males and of 92.9% of females was determined correctly. The correctness of the classification by sex is 100%.