Functional analysis of Thermus thermophilus transcription factor NusG

Transcription elongation factors from the NusG family are ubiquitous from bacteria to humans and play diverse roles in the regulation of gene expression. These proteins consist of at least two domains. The N-terminal domains directly bind to the largest, β′ in bacteria, subunit of RNA polymerase (RNAP), whereas the C-terminal domains interact with other cellular components and serve as platforms for the assembly of large nucleoprotein complexes. Escherichia coli NusG and its paralog RfaH modify RNAP into a fast, pause-resistant state but the detailed molecular mechanism of this modification remains unclear since no high-resolution structural data are available for the E. coli system. We wanted to investigate whether Thermus thermophilus (Tth) NusG can be used as a model for structural studies of this family of regulators. Here, we show that Tth NusG slows down rather than facilitates transcript elongation by its cognate RNAP. On the other hand, similarly to the E. coli regulators, Tth NusG apparently binds near the upstream end of the transcription bubble, competes with σA, and favors forward translocation by RNAP. Our data suggest that the mechanism of NusG recruitment to RNAP is universally conserved even though the regulatory outcomes among its homologs may appear distinct

The influence of porosity on the elasticity and strength of alumina and zirconia ceramics

This work investigates the behavior of porous alumina (with the porosity ranging from 18% to 70%) and zirconia (with the porosity ranging from 10% to 60%) ceramics when subjected to deformation by compression and shearing. The analysis of stress-strain curves showed that there is a transition from a typical brittle state for relatively dense ceramics, to a pseudo-plastic one for ceramics with high porosity. The values of the effective Young’s modulus, effective shear modulus and Poisson’s ratio decrease with the increase of the pore space volume of ceramics, which correlates with the appearance of multiple cracking during the deformation of the high porosity ceramics

Structures Formation on the Y-TZP-AI[2]O[3] Ceramic Composites Surface

The paper discusses the structure of Y-TZP-Al[2]O[3] ceramics produced from nanopowders and friction surface, wear resistance, friction coefficient of Y-TZP-AEO[3] composites rubbed against a steel disk counterface at a pressure of 5 MPa in a range of sliding speeds from 0.2 to 47 m/s. Analysis by X-ray diffraction, scanning electron microscopy showed that the high wear resistance of Y-TZP-Al[2]O[3] composites at high sliding speeds is due to high-temperature phase transitions and protective film formation on the friction surface

Инновационный подход к автоматизированной фотоактивации посевных площадей посредством БпЛА с целью стимуляции роста культур

Фотоактивация растений посредством лазерной обработки является перспективным направлением развития современного аграрного производства. Обработка растений излучением с заданными характеристиками стимулирует развитие растений, формирование генеративных признаков и рост урожайности. Для автоматизации процесса фотоактивации больших посевных площадей предложен подход, основанный на использовании специализированной лазерной установки, монтируемой на беспилотный летательный аппарат (БпЛА). При помощи БпЛА можно производить лазерную обработку сельскохозяйственных полей большой площади при минимальных затратах временных и человеческих ресурсов. В работе предложен алгоритм расчета траектории для равномерного покрытия прямоугольного участка земли лазерным излучением с заданными характеристиками. Приводится методика расчета требуемой мощности лазерной установки в зависимости от высоты и времени полета БпЛА. Преимуществом разработанного подхода является его универсальность, поскольку данный подход учитывает характеристики лазерного устройства и может применяться с устройствами различного типа. В зависимости от параметров лазера алгоритм строит такую траекторию для БпЛА, чтобы облучение всходов растений было равномерным на протяжении всего процесса обработки. При проведении полевых экспериментов при движении БпЛА вдоль рассчитанной траектории со скоростью 0,3 м/c время обработки поля длиной в 200 м и шириной 1 м составило 9 мин. Результаты полевых экспериментов показывают, что лазерное облучение для большей части изучаемых культур увеличило урожайность и высоту травостоя (у злаковых – для четырех из шести культур, у бобовых – для четырех из пяти изучаемых культур). Предлагаемый алгоритм построения пути для равномерного лазерного облучения участка учитывает площадь проекции лазерного излучения для обеспечения требуемых характеристик обработки поля

Multiple roles of the RNA polymerase β′ SW2 region in transcription initiation, promoter escape, and RNA elongation

Interactions of RNA polymerase (RNAP) with nucleic acids must be tightly controlled to ensure precise and processive RNA synthesis. The RNAP β′-subunit Switch-2 (SW2) region is part of a protein network that connects the clamp domain with the RNAP body and mediates opening and closing of the active center cleft. SW2 interacts with the template DNA near the RNAP active center and is a target for antibiotics that block DNA melting during initiation. Here, we show that substitutions of a conserved Arg339 residue in the Escherichia coli RNAP SW2 confer diverse effects on transcription that include defects in DNA melting in promoter complexes, decreased stability of RNAP/promoter complexes, increased apparent KM for initiating nucleotide substrates (2- to 13-fold for different substitutions), decreased efficiency of promoter escape, and decreased stability of elongation complexes. We propose that interactions of Arg339 with DNA directly stabilize transcription complexes to promote stable closure of the clamp domain around nucleic acids. During initiation, SW2 may cooperate with the σ3.2 region to stabilize the template DNA strand in the RNAP active site. Together, our data suggest that SW2 may serve as a key regulatory element that affects transcription initiation and RNAP processivity through controlling RNAP/DNA template interactions

THE IMPACT OF REHABILITATION ON QUALITY OF LIFE OF PATIENTS WITH ACUTE CORONARY SYNDROME WITH EMERGENCY REVASCULARIZATION BY PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY AND STENTING THE CORONARY ARTERIES (KRASNOYARSK)

Background. To study the dynamics in the quality of life of patients with acute coronary syndrome (ACS) with emergency revascularization by percutaneous transluminal coronary angioplasty and stenting the coronary arteries (CA). Materials and methods. 150 patients with ACS, percutaneous transluminal coronary angioplasty and stenting the coronary arteries (CA) were included. 65 patients (group 1) performed all procedures of second phase of cardiac rehabilitation program. 85 patients (group 2), who refused of participation in rehabilitation program, were tested according to the test-questionnaire Beck and SF-36. Results. Patients with a full course of rehabilitation program had a statically significant increase in health indicators (physical health component after discharge 42,30 [38,25; 44,35] in 6 months 56,30 [51,85; 5,810], p<0,001; psychological component after discharge 42,80 [39,75; 50,20] in 6 months 56,70 [51,85; 57,20], p<0,001). In group 2 there was no such pattern noticed. Tobacco smoking influenced physical (r = - 0,629, p<0,05) and psychological (r = - 0,621, p<0,05) components of health negatively. Also increased cholesterol influenced physical (r = - 0,424, p<0,05) and psychological (r = - 0,405, p<0,05) components of health. Conclusions. the high importance of rehabilitation program in patients after inpatient ACS treatment, percutaneous transluminal coronary angioplasty and stenting the coronary arteries was revealed. Increased cholesterol and smoking decrease the positive effect of rehabilitation

Transcription initiation factor DksA has diverse effects on RNA chain elongation

Bacterial transcription factors DksA and GreB belong to a family of coiled-coil proteins that bind within the secondarychannel of RNA polymerase (RNAP). These proteins display structural homology but play different regulatory roles. DksA disrupts RNAP interactions with promoter DNA and inhibits formation of initiation complexes, sensitizing rRNA synthesis to changes in concentrations of ppGpp and NTPs. Gre proteins remodel the RNAP active site and facilitate cleavage of the nascent RNA in elongation complexes. However, DksA and GreB were shown to have overlapping effects during initiation, and in vivo studies suggested that DksA may also function at post-initiation steps. Here we show that DksA has many features of an elongation factor: it inhibits both RNA chain extension and RNA shortening by exonucleolytic cleavage or pyrophosphorolysis and increases intrinsic termination in vitro and in vivo. However, DksA has no effect on Rho- or Mfd-mediated RNA release or nascent RNA cleavage in backtracked complexes, the regulatory target of Gre factors. Our results reveal that DksA effects on elongating RNAP are very different from those of GreB, suggesting that these regulators recognize distinct states of the transcription complex

Self-Lubricating Effect of FeWO₄ Tribologically Synthesized from WC-(Fe-Mn-C) Composite during High-Speed Sliding against a HSS Disk

WC-(Fe-Mn-C) composites with γ-iron and γ + α’ matrices were sintered and then tested at sliding speeds in the range 7–37 m/s. The coefficient of friction was exponentially reduced as a function of sliding speed reaching its minimum at 37 m/s. This behavior was provided by the mechanochemical formation of iron tungstate FeWO4 on the worn surfaces of composite samples. The lubricating effect of iron tungstate did not, however, allow for a reduction in wear. The worn surface was represented by a 3–10 μm-thickness tribological layer composed of fine WC and iron particles cemented by FeWO4. This layer provided the self-lubricating effect in high-speed (high-temperature) sliding because of its easy shear and quasi-viscous behavior. The underlying 25–65 μm of thickness layer was composed of only heat-affected WC and recrystallized iron grains