Dimeric G-quadruplex motifs-induced NFRs determine strong replication origins in vertebrates.

Replication of vertebrate genomes is tightly regulated to ensure accurate duplication, but our understanding of the interplay between genetic and epigenetic factors in this regulation remains incomplete. Here, we investigated the involvement of three elements enriched at gene promoters and replication origins: guanine-rich motifs potentially forming G-quadruplexes (pG4s), nucleosome-free regions (NFRs), and the histone variant H2A.Z, in the firing of origins of replication in vertebrates.

Condensin-Mediated Chromosome Folding and Internal Telomeres Drive Dicentric Severing by Cytokinesis.

In Saccharomyces cerevisiae, dicentric chromosomes stemming from telomere fusions preferentially break at the fusion. This process restores a normal karyotype and protects chromosomes from the detrimental consequences of accidental fusions. Here, we address the molecular basis of this rescue pathway.

The IGH locus relocalizes to a "recombination compartment" in the perinucleolar region of differentiating B-lymphocytes.

The immunoglobulin heavy chain (IGH) gene loci are subject to specific recombination events during B-cell differentiation including somatic hypermutation and class switch recombination which mark the end of immunoglobulin gene maturation in germinal centers of secondary lymph nodes. These two events rely on the activity of activation-induced cytidine deaminase (AID) which requires DNA double strand breaks be created, a potential danger to the cell. Applying 3D-fluorescence in situ hybridization coupled with immunofluorescence staining to a previously described experimental system recapitulating normal B-cell differentiation ex vivo, we have kinetically analyzed the radial positioning of the two IGH gene loci as well as their proximity with the nucleolus, heterochromatin and γH2AX foci.

Cytokinesis breaks dicentric chromosomes preferentially at pericentromeric regions and telomere fusions.

Dicentric chromosomes are unstable products of erroneous DNA repair events that can lead to further genome rearrangements and extended gene copy number variations. During mitosis, they form anaphase bridges, resulting in chromosome breakage by an unknown mechanism. In budding yeast, dicentrics generated by telomere fusion break at the fusion, a process that restores the parental karyotype and protects cells from rare accidental telomere fusion.

Analysis of RNA cleavage by RNA polymerases from Escherichia coli and Deinococcus radiodurans.

RNA polymerase can both synthesize and cleave RNA. Both reactions occur at the same catalytic center containing two magnesium ions bound to three aspartic acid residues of the absolutely conserved NADFDGD motif of the RNA polymerase beta subunit. We have demonstrated that RNA polymerase from Deinococcus radiodurans possesses much higher rate of intrinsic RNA cleavage than RNA polymerase from Escherichia coli (the difference in the rates is about 15-fold at 20 degrees C).

Structural modules of RNA polymerase required for transcription from promoters containing downstream basal promoter element GGGA.

We recently described a novel basal bacterial promoter element that is located downstream of the -10 consensus promoter element and is recognized by region 1.2 of the sigma subunit of RNA polymerase (RNAP). In the case of Thermus aquaticus RNAP, this element has a consensus sequence GGGA and allows transcription initiation in the absence of the -35 element.

Lineage-specific amino acid substitutions in region 2 of the RNA polymerase sigma subunit affect the temperature of promoter opening.

Highly conserved amino acid residues in region 2 of the RNA polymerase sigma subunit are known to participate in promoter recognition and opening. We demonstrated that nonconserved residues in this region collectively determine lineage-specific differences in the temperature of promoter opening.

Specific recognition of the -10 promoter element by the free RNA polymerase sigma subunit.

Bacterial RNA polymerase holoenzyme relies on its sigma subunit for promoter recognition and opening. In the holoenzyme, regions 2 and 4 of the sigma subunit are positioned at an optimal distance to allow specific recognition of the -10 and -35 promoter elements, respectively. In free sigma, the promoter binding regions are positioned closer to each other and are masked for interactions with the promoter, with sigma region 1 playing a role in the masking.

A basal promoter element recognized by free RNA polymerase sigma subunit determines promoter recognition by RNA polymerase holoenzyme.

During transcription initiation by bacterial RNA polymerase, the sigma subunit recognizes the -35 and -10 promoter elements; free sigma, however, does not bind DNA. We selected ssDNA aptamers that strongly and specifically bound free sigma(A) from Thermus aquaticus. A consensus sequence, GTA(C/T)AATGGGA, was required for aptamer binding to sigma(A), with the TA(C/T)AAT segment making interactions similar to those made by the -10 promoter element (consensus sequence TATAAT) in the context of RNA polymerase holoenzyme.

[Electrical and magnetic fields of the elementary bioelectric generator in the bounded anisotropic myocardium].

Using the equations of electrodynamics of stationary currents, relationships were derived for calculating the characteristics of electric and magnetic fields of an elementary (dipole) bioelectric generator in a heterogeneous medium consisting of two regions namely, an anisotropic conducting region corresponding to the excitable myocardium tissue and an isotropic conducting or dielectric region corresponding to the space outside the myocardium where the measurement is made. The shape of distributions of the electric potential and magnetic induction at the myocardium surface was determined, and the effect of anisotropy on these distributions was estimate. Formulas for the identification of the local excited zone within the myocardium from electric and magnetic measurements outside the excitable tissue or on its surface were obtained.

[Electric and magnetic fields of the closed depolarization front in the anisotropic myocardium].

On the basis of the bidomain model of anisotropic myocardium, mathematical relationships for calculating the characteristics of the extracellular electric and magnetic fields outside a closed or open depolarization front were derived on the assumption that the generator and fields are axially symmetric with respect to the longitudinal direction of the fibres making up the excitable tissue. The spatial configuration of the fields was determined and quantitative estimates were obtained for the electric potential and magnetic induction caused solely by the macroscopic anisotropy of the myocardium tissue as a volume conductor.

[An elementary bioelectrical generator of the anisotropic homogeneous myocardium and its extracellular field].

On the basis of the bidomain model that takes into account the electric anisotropy of body tissues, analytical relationships were developed for calculating the characteristics of electric and magnetic fields produced by an elementary (dipole) bioelectric generator that arises in the electrogenic excitable tissue of the myocardium. The errors in the identification of intensity and location of the bioelectric generator in the myocardium were estimated from the measurements of its external fields (noninvasive identification of the excited region) using approximate methods based on isotropic models of the physical medium.

[The entomological and acarological situation in Nizhegorod Province].

Ixodes, persulcatus, I. ricinus, D. reticulatus, D.

[A model of spherical quasi-epicardium for mapping of the electrical potential of the heart].

Possibility of determination of the heart electric potential maps on the spherical quasiepicardium from the body surface potentials measured by means of multiple leads, is estimated. The simplified models of ventricular depolarization electric generator considered in this study, consist of sets of uniform double layers representing basic configurations of the true electric generator of the heart, while allowing an analytical calculation of the multipole components, as well as potential of the generator. The contribution of the generator multipole components to the potential on the spherical quasiepicardium is evaluated.

Decarto technique in long-term observation of patients treated for primary pulmonary hypertension.

Techniques for noninvasive observation of heart states play an important part in experimental and therapeutic cardiology. The objective of this work is to describe a new method for intelligible pictorial representation of data acquired by an orthogonal electrocardiographic lead system and demonstration of possibilities of this method in estimating the results of longterm treatment for a cardiac disease. The method used, dipole electrocardiotopography (DECARTO), provides a set of maps (decartograms) that depict in an explicit form the instantaneous, as well as integral electrophysiological properties of the heart during the excitation cycle.

[The functional and sonographic parallels in chronic pancreatitis].

Ultrasonic histogramme was studied in 35 patients with chronic pancreatitis and 20 donors, taken in the area of the head and body of the pancreas, as were levels of immunoreactive trypsin--fasting and after standard food load,--and C-peptide in blood serum on an empty stomach. To increase informative value and specificity of ultrasonic and radioimmunologic investigations an index has been suggested, based on the findings from histogramme and radioimmunity analysis.

[2 outbreaks of trichinelliasis in Rostov Province].

Two epidemiologically unrelated outbreaks of trichinellosis were registered in Rostov Province in the November and December of 1984 with 16 patients in the Salsk District and 20 patients in Rostov-on-Don. The course of the disease was characterized by 6-20% of severe and 31-45% moderate forms, respectively. The source of the infection was pork that had not been controlled for Trichinella spiralis.

[Embovin efficacy and tolerance in the treatment of patients with intestinal nematode infections].

The efficacy and tolerance of embovin, a new anthelminthic manufactured in Russia, was studied in 60 patients with nematodiases. The results evidence its high efficacy in ankylostomiasis (100%), enterobiasis (100%), and ascariasis (90 +/- 6.4%).