Obtaining of intrapopulational dissociants of some bacilli and the use of DIR-PCR for their identification

The paper is the first to suggest methods for rapid obtaining and genotypic identification of phenotypic (colonial-morphological) dissociants of bacterial cultures. For revelation of the potential dissociation ability and obtaining of dissociants, the use of bacterial cyst-like refractile cells (CRC) is recommended. These cells are characterized by enhanced variability; upon their first passage, an abrupt increase in the dissociation index is observed as a result of the emergence of cells that form morphologically different types of colonies. The approaches elaborated were tested with Bacillus cereus, B. subtilis, and B. licheniformis, for which colonial-morphological dissociants of various types were obtained after the first passage of CRC (both of those formed in the developmental cycle of bacteria and of those arising as a result of artificial increase of the concentration of anabiosis autoinducers in the cultivation medium). The genomic distinctions between dissociants of B. cereus and B. subtilis were estimated using polymerase chain reaction with a primer system designed based on the analysis of nucleotide sequences of complete prokaryotic genomes available in the GenBank database (DIR-PCR). The application of the suggested method allowed distinctions between the genomes of dissociants of Bacillus cereus and B. subtilis to be revealed, which is in agreement with the hypothesis that suggests reversible intragenomic rearrangements to be the basis of bacterial dissociation into subpopulations.     

Correction of intestinal dysbacteriosis in elderly patients with the use of bifidobacterin introduced by different routes

The results of the correction of disturbances in intestinal microflora in elderly patients with the use of bifidumbacterin in the form of powder or suppositories are presented. The effectiveness of the rectal administration of bifidumbacterin (by microinjections through an enema or in suppositories) is shown in comparison with the oral administration of the preparation. The administration of bifidumbacterin in suppositories for 15 days resulted in decreased content of hemolytic Escherichia below the threshold of determination in all examined patients.     

Larvae of related Diptera species from thermally contrasting habitats exhibit continuous up-regulation of heat shock proteins and high thermotolerance

A population of Stratiomys japonica, a species belonging to the family Stratiomyidae (Diptera), common name ‘soldier flies’, occurs in a hot volcanic spring, which is apparently among the most inhospitable environments for animals because of chemical and thermal conditions. Larvae of this species, which naturally often experience temperatures more than 40 °C, have constitutively high concentrations of the normally inducible heat-shock protein Hsp70, but very low level of corresponding mRNA. Larvae of three other species of the same family, Stratiomys singularior, Nemotelus bipunctatus and Oxycera pardalina, are confined to different type semi-aquatic habitats with contrasting thermal regime. However, all of them shared the same pattern of Hsp70 expression. Interestingly, heat-shock treatment of S. japonica larvae activates heat-shock factor and significantly induces Hsp70 synthesis, whereas larvae of O. pardalina, a species from constant cold environment, produce significantly less Hsp70 in response to heat shock. Adults of the four species also exhibit lower, but detectable levels of Hsp70 without heat shock. Larvae of all species studied have very high tolerance to temperature stress in comparison with other Diptera species investigated, probably representing an inherent adaptive feature of all Stratiomyidae enabling successful colonization of highly variable and extreme habitats.     

Role of Phytohormones and Light in De-etiolation

Russian Journal of Plant Physiology - De-etiolation or transition from etiolated growth (skotomorphogenesis) to photomorphogenesis is one of the most intriguing and intricate stages of plant...     

Experimental model of hepatitis A in rhesus monkeys (Macaca mulatta) infected with human hepatitis A virus

The focus of this paper is characterization of Hepatitis A experimental model obtained for the first time in rhesus monkeys (M. mulatta) infected with fecal isolate from a patient with Hepatitis A (HAV-H1). Monkeys were susceptible to oral and intravenous routes of HAV inoculation. The disease could be reproduced regularly in 4 passages as a result of which HAV strain continuously pathogenic for M. mulatta has been established. All 17 infected monkeys developed Hepatitis A with characteristic (except jaundice) patterns: shedding of virus with the stool, elevations of serum alanine aminotransferase level, appearance of IgM anti-HAV, morphological changes developed in the liver. Our data have demonstrated that the course of experimental Hepatitis A infection in M. mulatta is similar (in many respects) to that observed in man.     

Comparative Analysis of Mono- and Bifunctional Chorismate Synthases in <Emphasis Type="Italic">Escherichia coli</Emphasis> Cells Capable and Incapable of Phenylalanine Production

The activity of chorismate synthase, the terminal enzyme of the common aromatic pathway, is absolutely dependent on reduced flavin mononucleotide. The bifunctional chorismate synthase of Saccharomyces cerevisiae (product of the ARO2 gene) can reduce flavin in a reaction that involves NADPH, in contrast to the monofunctional chorismate synthase of Escherichia coli (product of the _aro C gene). The latter enzyme does not have the capacity for flavin reduction, and its activity therefore depends on the flavin reductase function of the cell. Chemical synthesis of the structural part of the ARO2 gene that involved the substitution of rare E. coli codons was performed for an in vivo comparison of the two types of chorismate synthase. ARO2 expression was tested in the T7 system, and isogenic E. coli strains TG1Δ _aro CP_tac-ARO2 and TG1Δ _aro CP_tac- _aro C were obtained. Comparative analysis of proteins from the cell extracts of these strains and in silico assessment of hybrid RBS efficiency showed that the level of AroC protein synthesis in TG1Δ _aro CP_tac- _aro C was higher than the level of ARO2 synthesis in the TG1Δ _aro CP_tac-ARO2 cells. The introduction of Ptac-ARO2 and Ptac- _aro C modifications led to complete recovery of the growth of the aromatic auxotroph TG1Δ _aro C on minimal mineral medium supplemented with glucose and restored phenylalanine production in the E. coli strain DV1017Δ _aro C, which lacked chorismate synthase activity. The similar positive effects of P_tac- _aro C and P_tac-ARO2 on phenylalanine biosynthesis in the DV1017ΔtyrR strain, in which chorismate synthase played a “bottleneck” role, indicated the absence of a limiting effect of reduced flavin on monofunctional chorismate synthase overexpressed in E. coli cells.