Efficiency of Xist-mediated silencing on autosomes is linked to chromosomal domain organisation

BACKGROUND: X chromosome inactivation, the mechanism used by mammals to equalise dosage of X-linked genes in XX females relative to XY males, is triggered by chromosome-wide localisation of a cis-acting non-coding RNA, Xist. The mechanism of Xist RNA spreading and Xist-dependent silencing is poorly understood. A large body of evidence indicates that silencing is more efficient on the X chromosome than on autosomes, leading to the idea that the X chromosome has acquired sequences that facilitate propagation of silencing. LINE-1 (L1) repeats are relatively enriched on the X chromosome and have been proposed as candidates for these sequences. To determine the requirements for efficient silencing we have analysed the relationship of chromosome features, including L1 repeats, and the extent of silencing in cell lines carrying inducible Xist transgenes located on one of three different autosomes. RESULTS: Our results show that the organisation of the chromosome into large gene-rich and L1-rich domains is a key determinant of silencing efficiency. Specifically genes located in large gene-rich domains with low L1 density are relatively resistant to Xist-mediated silencing whereas genes located in gene-poor domains with high L1 density are silenced more efficiently. These effects are observed shortly after induction of Xist RNA expression, suggesting that chromosomal domain organisation influences establishment rather than long-term maintenance of silencing. The X chromosome and some autosomes have only small gene-rich L1-depleted domains and we suggest that this could confer the capacity for relatively efficient chromosome-wide silencing. CONCLUSIONS: This study provides insight into the requirements for efficient Xist mediated silencing and specifically identifies organisation of the chromosome into gene-rich L1-depleted and gene-poor L1-dense domains as a major influence on the ability of Xist-mediated silencing to be propagated in a continuous manner in cis

High energy hadrons in EAS at mountain altitude

An extensive simulation has been carried out to estimate the physical interpretation of dynamical factors such as , in terms of high energy interaction features, concentrated in the present analysis on the average transverse momentum. It appears that the large enhancement observed for versus primary energy, suggesting in earliest analysis a significant rise of with energy, is only the result of the limited resolution of the detectors and remains in agreement with a wide range of models used in simulations.Comment: 13 pages, 6 PostScript figures, LaTeX Subm. to JPhys

X-ray film chamber with carbon target of Tien-Shan complex array

X-ray films were exposed inside the ionization calorimeter under 74g/sq cm of carbon and 5 cm of lead. The X-ray film chamber area is 35 sq. m. Moving X-ray films were used, 50% of the events, which succeeded to determine incidence time, were identified with corresponding extensive air showers (EAS). For such events the size spectrum of associated EAS was derived. Two methods of energy measurement using X-ray films and ionization calorimeter were compared. The energy transfer from selected hadron to electromagnetic component is illustrated. It is found that in cascades with high energy release into electromagnetic components the hadron component is practically absent

The influence of gasifier operating parameters on syngas composition of coal-fired power plant with CO2capture

This work investigated the influence of the operating parameters of the gasifier (pressure, temperature of the syngas at the outlet of the gasifier and the O2/CO2 ratio in the blast) on the composition of the syngas in relation to the Allam cycles and oxy-fuel IGCC. Thermodynamic modeling of the operation of Shell (Allam cycle) and MHI (oxy-fuel IGCC cycle) gasifiers by the entropy maximization method was carried out. For the Shell gasifier, a significant increase in methane concentration with an increase in pressure to 40 MPa has been revealed; it indicates the need to make changes to the syngas gas cleaning system. The optimal temperature at the outlet of the gasifier (1100°C) has been found for the MHI gasifier. At this temperature, there were high values of CO and H2, and, hence, the heating value of syngas. For both gasifiers, the most theoretically reasonable ratio of O2/CO2 in blast was 0.3, at which CO reached almost maximum values and decreased its growth rate. © Published under licence by IOP Publishing Ltd.Government Council on Grants, Russian FederationThe work was supported by the Act 211 of the Government of the Russian Federation, contract № 02.A03.21.0006

Development of the procedure of testing with the application of the expert evaluation method in psychophysiology

This article provides a detailed description of the stages of development of an information system of personalized psychophysiological testing using expert evaluation. The process of the information system design is presented, the developed functional models, database and algorithm of testing by students-experts are demonstrate

COMPARISON OF TURBULENCE MODELS ON THE EXAMPLE OF ENTRAINED-FLOW SINGLE-STAGE GASIFIER

Comparison of CFD modeling results obtained using different turbulence models and without them on the example of gasifier hydrodynamics modeling is carried out. Using models gives a different result than the case without using them.Проведено сравнение результатов CFD-моделирования, получаемых при использовании разных моделей турбулентности и без них, на примере моделирования гидродинамики газификатора. Использование моделей дает результат, отличный от случая без их использования