Effect of osmotic shock on the viability, optical density and permeability of heated Escherichia coli cells

The object of this work was to study the effect of a short incubation in 0.01 M tris buffer, pH 7.0, with a different NaCl content (0-10%) on the viability, optic density and permeability of intact and heated at 52 degrees C Escherichia coli B/r cells. In contrast to the intact cells, the viability of the heated cells depended on osmotic pressure in the medium into which they were transferred after heating. The survival rate was highest when the cells were transferred into an isotonic buffer. In the case of hypotonic and hypertonic media, the survival rate of the cells decreased owing to the death of cells which were responsible for the formation of small colonies under the isotonic conditions. This was accompanied with a more intensive drop in the optic density of bacterial suspensions while their permeability increased (when the cells were transferred into the hypotonic conditions). The role of membranes in the processes of bacterial heat inactivation is discussed on the basis of the results obtained.     

RNA-binding properties of the plant protein Nt-4/1

The tobacco α-helical protein Nt-4/1 with unknown function forms ribonucleoprotein (RNP) complexes in vitro. Results obtained by retardation of RNP complexes in agarose gel were confirmed by Western-Northern hybridization. Several deletion and point mutants of Nt-4/1 were constructed, and the RNA-binding site was mapped in a positively charged region of the C-terminal domain of the protein. The results of this study and those described earlier support our hypothesis of the participation of Nt-4/1 protein in spreading RNA-containing pathogens in the plant.     

Superoxide anion production by the mitochondrial respiratory chain of hepatocytes of rats with experimental toxic hepatitis

The progression of toxic hepatitis is accompanied by the activation of oxidative processes in the liver associated with an enhancement of the mitochondrial respiratory chain activity and superoxide anion production (О₂^˙-). The purpose of this study was to examine our previously formulated assumption concerning the predominant contribution of the complex I to О₂^˙- production increase by the mitochondrial respiratory chain of hepatocytes in toxic hepatitis (Shiryaeva et al. Tsitologiia, 49, 125–132 2007). Toxic hepatitis was induced by a combined application of ССl₄ and ethanol. Respiratory chain function analysis was executed with submitochondrial particles (SP) in the presence of specific inhibitors. It was shown that the rate of О₂^˙- production by SP of animals with toxic hepatitis, when NADH was delivered, was 2.5-fold higher as compared with the control. The rates of О₂^˙- production by SP of rats with toxic hepatitis in the presence of NADH or NADH + rotenone were similar. The О₂^˙- production rate by control SP in the presence of NADH + rotenone corresponded to the О₂^˙- production rate by toxic hepatitis SP when only NADH was delivered. When NADH + myxothiazol were delivered to the incubation system, О₂^˙- production by toxic hepatitis SP was 72% higher than for the control. Conversely, in the presence of antimycin A, the production of О₂^˙- by toxic hepatitis SP was lower compared to the control. Collectively, the presented data indicate that the О₂^˙- production rate was enhanced by the complex I of the hepatocyte mitochondrial respiratory chain in experimental toxic hepatitis. Complex III contribution to the production of О₂^˙- was insignificant. We assume that the increase in О₂^˙- production by the respiratory chain may be considered not only as the mechanism of pathology progression, but also as a compensatory mechanism preserving the electron transport function of the mitochondrial respiratory chain when complex I functioning is blocked in part.     

New Polymorphic Sites in the Human Phenylalanine Hydroxylase Gene

A previously unknown sequence of the human phelylalanine hydroxylase (PAH) gene intron 7 (GeneBank AN AF204239) has been reported. Screening of the group of phenylketonuria patients from Nobosibirsk region for polymorphic sites within intron 7 revealed single nucleotide substitutions at intron positions 332, 451, 574 and 791. Polymorphic site at intron position 791 corresponds to one of the eight restriction sites (MspI) utilized for haplotype construction. Analysis of the MspI allele frequencies in 29 phenylketonuria patients showed that the frequency of the MspI+ allele in this group was 79.4%. Polymorphic sites at nucleotide position +97 from the beginning of intron 10, and at nucleotide position –54 from the end of intron 5, were also described. The polymorphic sites revealed can be used as markers for identification of the PAH alleles in population genetic studies, and also serve for diagnostics of phenylketonuria (PKU). The presence of numerous nucleotide substitutions within the intronic sequences confirms highly polymorphic structure of the PAH gene.     

On Problems of the Comprehensive Chemical Profiling of Medicinal Plants

Russian Journal of Bioorganic Chemistry - The interest in and attention to herbal therapy rise in Russia every year, which is in agreement with the worldwide tendency. Support for the increasing...     

Antibodies against structural proteins of carlaviruses in human and other mammals

The study of four isolates of chrysanthemum B-virus (CVB) has shown the virus to have a single 40 Kd structural protein able to dissociate under the definite conditions forming the truncated (for 3 and 6 Kd) polypeptides having preserved their whole antigenic determinants. The human plasma is shown to contain antibodies reacting with the structural protein B-BX and, approximately 10 times weaker with the structural protein of another carlavirus, potato M-virus. Interaction of antibodies with CVB is found to take place due to F(ab)2 fragments. The analogous reaction with the proteins of other plant viruses or retroviruses has never been registered. Antibodies reacting with CVB protein are also present in the plasma of green monkey, rabbit, mouse and goat but in lesser quantities than in human plasma. Two possible explanations are proposed for the presented data, either immunization of mammalians by the protein or peptide containing its antigenic determinant, or the accidental coincidence of CVB antigenic determinant with some viral, bacterial or fungal determinant widespread in mammalians.