Conformational stability of glutamate dehydrogenase and its complexes with specific ligands

The isotermic denaturation of glutamatdehydrogenase (GDH) and its complexes with co-enzymes, substrates and allosteric regulators under the action of urea was studied. It was shown that the reaction of the enzyme with an allosteric inhibitor GTP is accompanied by a decrease in conformational stability of the catalytically active hexsamer GDH. Formation of a complex with the allosteric activator ADP increases the conformational stability of the enzyme. Studies on the isotermic unfolding of GDH in the presence of various phosphoric ethers of adenosine gave evidence that the stabilizing effect of ADP is based on the reaction of the enzyme with the adenine base of the regulator.     

Transgenic Tobacco plants expressing bacterial genes encoded the thermostable glucanases

It is shown that bacterial genes for thermostable beta-glucanases are expressed retaining their activity and substrate specificity. The leader peptide of the carrot extensin exerts effective secretion of the bacterial enzymes into the intercellular space of the plant tissue. Expression of the bacterial gene for beta-1,3-glucanase in plant tissues alters their morphogenetic potential. Regeneration of shoots from the calli of these plant lines requires a six- to eightfold increase in cytokinin (6-BAP) concentration in comparison with the control lines and the transgenic lines expressing beta-1,3-1,4-glucanase. Rooting of transgenic plants expressing the bacterial gene for beta-1,3-glucanase occurs much faster. The transgenic plants obtained in the study are proposed as model objects for investigating the role of glucanases in plants.     

Phenetic analysis in paleoanthropology: phenogeography of peoples of the world

Phenetic diversity of peoples of the world in a system of nonmetric, discrete variable traits has been studied. Sixty-two populations from North, Central, and Southeast Asia, Eastern and Western Europe, America, East Africa, Australia and Melanesia have been examined. The estimates of phenetic diversity within regions (F(st)) and the distances of the regions from the global means (d) proved to be comparable to the corresponding estimates inferred from genetic data. This means that differentiation of populations in discrete variable traits is related to the history of formation of their gene pools. A classification tree of the world peoples constructed using bootstrap implemented in the PHYLIP program package (Felsenstein, 1993) showed that the Australo--Melanesian populations were close to the East African ones but separated from those of the Eurasian region. The results of phylogenetic analysis of the reconstructed phene pools of the regional ancestral populations support the assumptions on the early colonization of Australia and Melanesia and on the later time of divergence of the ancestors of modern Caucasoids and North Asian Mongoloids.     

The cytogenetic effect of natural modifiers of mutagenesis in a human lymphocyte culture: the modification of the mutagenic effect by recombinant interferon in vitro in the lymphocytes of bronchial asthma patients and of healthy donors]

The significant protective effect of recombinant interferon in the cultures of lymphocytes of healthy donors and patients with bronchial asthma has been revealed. The cytogenetic damage were stimulated by alkylating agents thioTEPA and photrin during their administration at the stages Gi-S of the cell cycle. No differences were revealed in the action of mutagens and protector in the patients and healthy persons.     

Regulation of phenylacetic acid degradation genes of Burkholderia cenocepacia K56-2

Background  

Metabolically versatile soil bacteria Burkholderia cepacia complex (Bcc) have emerged as opportunistic pathogens, especially of cystic fibrosis (CF). Previously, we initiated the characterization of the phenylacetic acid (PA) degradation pathway in B. cenocepacia, a member of the Bcc, and demonstrated the necessity of a functional PA catabolic pathway for full virulence in Caenorhabditis elegans. In this study, we aimed to characterize regulatory elements and nutritional requirements that control the PA catabolic genes in B. cenocepacia K56-2.     

Inositol trisphosphate does not release Ca2+ from permeabilized cardiac myocytes and sarcoplasmic reticulum

The possibility that inositol 1,4,5-trisphosphate (IP3) may act as a Ca2+-mobilizing second messenger in cardiac muscle in a manner analogous to its actions in other cell types has been examined using saponin-permeabilized myocytes and isolated cardiac sarcoplasmic reticulum. Myocytes permeabilized in the presence of MgATP2- sequestered Ca2+ to a level of about 200 nM, similar to the cytosolic free Ca2+ concentration of intact cells, but addition of IP3 was ineffective in causing Ca2+ release from intracellular stores. Similarly, IP3 (up to 50 microM) was unable to inhibit Ca2+ uptake or cause Ca2+ release from isolated canine cardiac sarcoplasmic reticulum vesicles in the presence of either EGTA or sodium vanadate. These results indicate that IP3 is unlikely to mediate mobilization of intracellular Ca2+ stores in myocardial cells.     

Effect of interferon on the number of cytogenetic disorders occurring in human cultured lymphocytes treated with thio-TEPA and fotrin

The paper deals with the modifying effects of natural (leukocytic) and synthesized (recombinant) interferons on the number of cytogenetic injuries in the cultured lymphocytes of human peripheric blood after exposure to alkylating chemicals--thio-TEPA and fotrin. The analysis of chromosomal aberration levels is suggestive of a significant protective effect exerted by interferons. The addition of the recombinant interferon increased the number of sister chromatid exchanged frequency in mutagen treated variants. The application of the test system that involves two types of interferon made it possible to reveal differences in their cytogenetic effect during the protector-sensitive period of cultivation.