Spin-transfer mechanism of ferromagnetism in polymerized fullerenes: AbinitioAb initio calculations

A mechanism of the high temperature ferromagnetism in polymerized fullerenes is suggested. It is assumed that some of the C$_{60}$ molecules in the crystal become magnetically active due to spin and charge transfer from the paramagnetic impurities (atoms or groups), such as hydrogen, fluorine, hydroxyl group OH, amino group NH$_2$, or methyl group CH$_3$, dispersed in the fullerene matrix. The exchange interaction between the spins localized on the magnetically active fullerenes is evaluated using \textit{ab initio} calculations. The nearest neighbour and next nearest neighbour exchange interaction is found to be in the range $0.1\div 0.3$ eV, that is, high enough to account for the room temperature ferromagnetism.Comment: typos corrected, 8 pages, 3 figures, LaTe

Paraffin embedded cancer tissue 2D terahertz imaging and machine learning analysis

Absorption spectra of paraffin-embedded prostate and adenocarcinoma cancer tissues an

Supramolecular strategy to construct quantum dot-based sensors for detection of paraoxon

© 2018 Elsevier B.V. The development of advanced tools for sensing specific materials remains an ongoing challenge. Detailed below is a new quantum dot (QD)-based sensor via supramolecular interactions, demonstrating a novel simplicity of design to obtain sensitive QDs while avoiding their covalent cross-linking. A simple label-free and turn-off method for the detection of paraoxon and its degradation products in aqueous media was proposed by using the fluorescent QD/surfactant/cyclodextrin supramolecular system. This nanocomposite was prepared from 3-mercaptopropionic acid-capped CdTe QDs coated with cetyltrimethylammonium bromide (CTAB) through electrostatic self-assembly. Further nanocomposite modification by β-cyclodextrin (β-CD), thanks to hydrophobic interaction between cetyl tails of surfactants and inner cavity of macrocycle contributed to an increase in emission intensity and stability in aqueous solution. The strong fluorescence of CdTe/CTAB/β-CD nanocomposite can be effectively quenched by the addition of paraoxon due to the host–guest complexation between β-CD cavity and paraoxon degradation product. The functionality of the paraoxon sensor was also tested with blood samples of paraoxon-poisoned rats (1/2 × LD50). These fluorescent nanocomposites were obtained by using the simple supramolecular method to coat QDs with surfactant–cyclodextrin shells. This coating strategy potentially offers common method for the functionalization of QDs and avoids time-consuming synthesis procedures

Влияние физической нагрузки на концентрацию эндотелиальной NO-синтазы и фактора активации тромбоцитов в плазме у спортсменов

 Aim. To assess the effect of a single physical activity on the concentration of endothelial NO-synthase and plateletactivating factor in blood plasma of athletes training in cyclic and strength sports, as well as in untrained volunteers.Materials and methods. The study involved 28 men aged 18–25 years, who were relatively healthy and had no disorders of the cardiovascular system. Three groups were formed according to the sports classification. Group 1 (TFG): highly qualified athletes (Candidates for Master of Sports (CMS),  Master of Sports (MS)) of cyclic sports – track and field athletics (middle-distance running, 800–1500 m), n = 10. Group 2 (WG): highly qualified athletes (CMS, MS) of strength sports – weightlifting, n = 8. Group 3 (CG): control group – untrained men with no sports category, n = 10. All volunteers were examined in the morning on an empty stomach. One day before the study, the athletes were advised to stop the training process. The blood from cubital vein was taken from all the subjects three times: before exercise (test A), immediately after performing the standard PWC170 test on a bicycle ergometer (test B), and 60 minutes after performing the stress test (test C). Determination of the concentration of endothelial NO-synthase (eNOS) and platelet-activating factor (PAF) in plasma was performed by enzyme immunoassay.Results. It has been shown that the features of endothelial reactivity in athletes of various specializations in comparison with untrained volunteers are significantly associated with the level of eNOS production both at rest and in response to short-term physical exertion. Platelet-activating factor  can also affect endothelial reactivity, but to a lesser extent, and is involved only in the mechanisms of adaptation to repetitive high-intensity physical  loads.  Цель. Оценить влияние однократной физической нагрузки на концентрацию эндотелиальной NO-синтазы и фактора активации тромбоцитов в плазме крови у спортсменов, тренирующихся в циклических и силовых видах спорта, а также у нетренированных волонтеров.Материалы и методы. В исследовании участвовали 28 мужчин в возрасте 18–25 лет, условно здоровые, без нарушений со стороны сердечно-сосудистой системы. В соответствии со спортивной классификацией было сформировано три группы. Группа 1 (ЛА):  высококвалифицированные спортсмены (кандидаты в мастера спорта (КМС), мастера спорта (МС)) циклических  видов спорта – легкая атлетика (бег на средние дистанции 800–1 500 м), n = 10. Группа 2 (ТА):  высококвалифицированные спортсмены (КМС, МС) силовых видов спорта – тяжелая атлетика, n = 8. Группа 3 (КГ):  контрольная группа – нетренированные мужчины, не имеющие спортивного разряд, n = 10. Все волонтеры  проходили обследование утром натощак. За 1 сут до исследования спортсменам было рекомендовано  прекратить тренировочный процесс. У всех испытуемых  трижды бралась кровь из локтевой вены: до нагрузки  (проба А), сразу после выполнения стандартной пробы PWC170 на велоэргометре (проба В) и через 60 мин после выполнения нагрузочной пробы (проба С). Определение концентрации eNOS и PAF в плазме производилось методом иммуноферментного анализа.Результаты. Показано, что особенности эндотелиальной реактивности у спортсменов различных специализаций в сравнении с нетренированными волонтерами в  значительной степени связаны с уровнем продукции eNOS как в покое, так и в ответ на кратковременные физические  нагрузки. Фактор активации тромбоцитов также может оказывать влияние на эндотелиальную реактивность, но в  меньшей степени, и вовлекается только в механизмы адаптации к регулярным нагрузкам высокой интенсивности.

Fused eco29kIR- and M genes coding for a fully functional hybrid polypeptide as a model of molecular evolution of restriction-modification systems

<p>Abstract</p> <p>Background</p> <p>The discovery of restriction endonucleases and modification DNA methyltransferases, key instruments of genetic engineering, opened a new era of molecular biology through development of the recombinant DNA technology. Today, the number of potential proteins assigned to type II restriction enzymes alone is beyond 6000, which probably reflects the high diversity of evolutionary pathways. Here we present experimental evidence that a new type IIC restriction and modification enzymes carrying both activities in a single polypeptide could result from fusion of the appropriate genes from preexisting bipartite restriction-modification systems.</p> <p>Results</p> <p>Fusion of <it>eco29kIR </it>and <it>M </it>ORFs gave a novel gene encoding for a fully functional hybrid polypeptide that carried both restriction endonuclease and DNA methyltransferase activities. It has been placed into a subclass of type II restriction and modification enzymes - type IIC. Its MTase activity, 80% that of the M.Eco29kI enzyme, remained almost unchanged, while its REase activity decreased by three times, concurrently with changed reaction optima, which presumably can be caused by increased steric hindrance in interaction with the substrate. <it>In vitro </it>the enzyme preferentially cuts DNA, with only a low level of DNA modification detected. <it>In vivo </it>new RMS can provide a 10²-fold less protection of host cells against phage invasion.</p> <p>Conclusions</p> <p>We propose a molecular mechanism of appearing of type IIC restriction-modification and M.SsoII-related enzymes, as well as other multifunctional proteins. As shown, gene fusion could play an important role in evolution of restriction-modification systems and be responsible for the enzyme subclass interconversion. Based on the proposed approach, hundreds of new type IIC enzymes can be generated using head-to-tail oriented type I, II, and III restriction and modification genes. These bifunctional polypeptides can serve a basis for enzymes with altered recognition specificities. Lastly, this study demonstrates that protein fusion may change biochemical properties of the involved enzymes, thus giving a starting point for their further evolutionary divergence.</p

Analysing Dynamical Behavior of Cellular Networks via Stochastic Bifurcations

The dynamical structure of genetic networks determines the occurrence of various biological mechanisms, such as cellular differentiation. However, the question of how cellular diversity evolves in relation to the inherent stochasticity and intercellular communication remains still to be understood. Here, we define a concept of stochastic bifurcations suitable to investigate the dynamical structure of genetic networks, and show that under stochastic influence, the expression of given proteins of interest is defined via the probability distribution of the phase variable, representing one of the genes constituting the system. Moreover, we show that under changing stochastic conditions, the probabilities of expressing certain concentration values are different, leading to different functionality of the cells, and thus to differentiation of the cells in the various types