Cytogenetic studies of blood lymphocytes of cosmonauts after long-ter, space flights

An analysis was performed of unstable chromosomal aberrations in peripheral blood of 36 cosmonauts after long-term space missions on "Mir" orbital station. 25 cosmonauts were examined before their flights to score spontaneous yields of cytogenetical damage. In all cases the doses absorbed by crews during space flights did not exceed permissible levels of irradiation, adopted for cosmonauts. The frequencies of chromosomal-type aberrations after space missions were found to increase significantly compared to the pre-flight levels. The yields of dicentrics and centric rings on the average were as high as 0.12 +/- 0.02 and 0.47 +/- 0.06% before and after the 1st flight, 0.18 +/- 0.05 and 0.71 +/- 0.11% before and after the 2nd flight respectively. During the inter-flight periods, usually lasted 1.5-2 years, the yields of chromosome damage lowered, but did not reach their spontaneous values. After each next flight the yields of chromosome aberrations increased again. The cytogenetical damage detected in cosmonauts' peripheral blood lymphocytes after chronic action of low doses of space radiation points out a possible increase in risks of stochastic effects in distant future for crews after long-term space missions.     

The use of PCR for detecting genes that encode type I polyketide synthases in genomes of actinomycetes

PCR screening of type I polyketidesynthase genes (PKS) was conducted in genomes of actinomycetes, producers of antibiotics. Some DNA fragments from the Streptomyces globisporus 1912 strain, a producer of a novel angucycline antibiotic landomycin E, were amplified. These fragments shared appreciable homology with type I PKS controlling the biosynthesis of polyene antibiotics (pymaricin and nistatin). The cloned regions were used to inactivate putative type I PKS genes in S. globisporus 1912. Strains with inactivated genes of PKS module do not differ from the original strain in the spectrum of synthesized polyketides. Apparently, these are silent genes, which require specific induction for their expression. The method of PCR screening can be used in a large-scale search for producers of new antibiotics.     

Size-dependent fluorescence of dibenzoylmethanate and ditoluylmethanate of boron difluoride.

Significant differences in the luminescence properties of dibenzoylmethanate and ditoluylmethanate of boron difluoride bulk crystals and microcrystals were detected. The size-dependent blue-to-green colour change of the luminescence is connected with the band intensity redistribution of monomer and excimer luminescence and fluorescence due to interdimer interaction.     

Interspecies conjugation of Escherichia coli-Streptomyces globisporus 1912 using integrative plasmid pSET152 and its derivatives]

Streptomyces globisporus 1912 produces a novel angucycline antitumor antibiotic landomycin E (LE). To study the LE biosynthetic gene cluster in detail, a system for the conjugal transfer of the integrative plasmid pSET152 from Escherichia coli into S. globisporus 1912 has been developed. It was shown that this plasmid integrates into two sites of the S. globisporus chromosome and is stably inherited under nonselective conditions. pSET152+ exconjugants of the strain 1912 are characterized by a significant decrease in LE synthesis (by 50-90%). A negative effect of pSET152 integration on antibiotic production was observed even upon the use of the recipient strain with increased LE synthesis, although in this case, the level of LE production in ex-conjugants was 120-150% of that in the original strain 1912. Based on pSET152, a vector system for gene knockouts in S. globisporus was developed. The effectivity of this system was shown in the example of disruption of the lndA gene encoding the key enzyme of LE synthesis (beta-ketoacylsynthase). Inactivation of this gene was shown to lead to the cessation of LE biosynthesis.     

Association of the Level of Serum Prolactin with Polymorphic Variants of the GRIN2A,GPM3, and GPM7 Genes in Patients with Schizophrenia Taking Conventional and Atypical Antipsychotics

Molecular Biology - The dopamine, serotonin and glutamate systems are jointly involved in the pathogenesis and pharmacotherapy of schizophrenia. We formulated a hypothesis that polymorphic variants...     

Gene cloning system for sulfonamide-mineralizing <Emphasis Type="Italic">Microbacterium</Emphasis> sp<Emphasis Type="Italic">.</Emphasis> strain BR1

The wide application of sulfonamide (SA) antibiotics in human and veterinary medicine contributes to the accumulation of these antibiotics in the environment and the corresponding onset of antibiotic resistance among bacteria. Microbacterium sp. BR1 is capable of mineralizing sulfamethoxazole and other SAs via a novel mechanism. The genetic basis of SA elimination by BR1 remains unknown. Development of an efficient plasmid transfer protocol for Microbacterium sp. BR1 is highly desirable, as it would open the door to genetic analysis and manipulation of its genome. Here we report that intergeneric Escherichia coli–Microbacterium spp. BR1 conjugation is an efficient way to introduce various plasmids into BR1. The generated transconjugants were stable in the presence of antibiotics and the plasmids showed no signs of rearrangements. Nevertheless, the plasmids were rapidly lost in the absence of selection. We also show that the cumate-inducible beta-glucuronidase reporter gene functions in BR1 and is strictly regulated. Our results set the working ground for further genetic manipulations of BR1, such as the overexpression of sulfonamide degradation genes or the selection of strong microbacterial promoters.     

Changes in FLC and VIN3 Expression during Vernalization of Arabidopsisthaliana Plants from Northern Natural Populations

Russian Journal of Genetics - Specific expression patterns of the FLC and VIN3 genes, which play a key role in the vernalization-mediated transition to flowering of A. thaliana plants from northern...     

Spontaneously active ion channels of membranes of the nuclear envelope of hippocampal pyramidal neurons

The genetic apparatus of an eukaryotic cell is surrounded by two membranes of the nuclear envelope that forms a half-permeable barrier for the movement of molecules and ions. Using a patch-clamp technique in experiments on isolated nuclei of pyramidal neurons from the hippocampal CA1 area, we describe the biophysical properties of spontaneously active ion channels in the nuclear membranes of these cells. In the external nuclear membrane, we found anion channels with a unitary conductance of 156 pS and with very rapid kinetics of fluctuation, while in the inner membrane we recorded cationic channels with a unitary conductance of 248 pS and very slow kinetics. Channels of both types demonstrated clear voltage dependences. We hypothesize that the physiological importance of these channels is related to the function of the intermembrane space of the nuclear envelope of these cells forming a considerable calcium store. It seems possible that such channels in the nuclear membranes are necessary for the maintenance of the ion balance between the cytoplasm and perinuclear space and between the latter and karyoplasm, and also for neutralization of voltage shifts in the course of Ca²⁺ release. Neirofiziologiya/Neurophysiology, Vol. 39, No. 1, pp. 3–8, January–February, 2007.     

Application of intergeneric conjugation of <Emphasis Type="Italic">Escherichia coli — Streptomyces</Emphasis> for transfer of recombinant DNA into the strain <Emphasis Type="Italic">S. nogalater</Emphasis> IMET43360

Successful transfer of the plasmids studied here into S. nogalater IMET43360 cells by means of intergeneric conjugation in the system E. coli — Streptomyces has made the method a convenient means of constructing this strain. Through the use of DNA-DNA hybridization, the nature of the integration of the plasmids pVWB and pRT801 is determined and their influence on nogalamycin biosynthesis is studied. The results of our studies will help in gaining a more detailed understanding of the functioning of genes involved in the biosynthesis of nogalamicin in S. nogalater IMET43360. The use of conjugation for substitution and destruction of genes and heterologous expression makes it possible to obtain new “hybrid” antibiotics that can be produced by this strain.