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

Historical and recent aufeis in the Indigirka River basin (Russia)

A detailed spatial geodatabase of aufeis (or naled in Russian) within the Indigirka River watershed (305&thinsp;000&thinsp;km2), Russia, was compiled from historical Russian publications (year 1958), topographic maps (years 1970–1980s) and Landsat images (year 2013–2017). Identification of aufeis by late spring Landsat images was performed with a semi-automated approach according to Normalized Difference Snow Index (NDSI) and additional data. After this, a cross-reference index was set for each aufeis field to link and compare historical and satellite-based aufeis datasets. The aufeis coverage varies from 0.26&thinsp;% to 1.15&thinsp;% in different sub-basins within the Indigirka River watershed. The digitized historical archive (Cadastre, 1958) contains the coordinates and characteristics of 896 aufeis fields with a total area of 2064&thinsp;km2. The Landsat-based dataset included 1213 aufeis fields with a total area of 1287&thinsp;km2. Accordingly, the satellite-derived total aufeis area is 1.6 times less than the Cadastre (1958) dataset. However, more than 600 aufeis fields identified from Landsat images are missing in the Cadastre (1958) archive. It is therefore possible that the conditions for aufeis formation may have changed from the mid-20th century to the present. Most present and historical aufeis fields are located in the elevation band of 1000–1200&thinsp;m. About 60&thinsp;% of the total aufeis area is represented by just 10&thinsp;% of the largest aufeis fields. Interannual variability of aufeis area for the period of 2001–2016 was assessed for the Bolshaya Momskaya aufeis and for a group of large aufeis fields (11 aufeis fields with areas from 5 to 70&thinsp;km2) in the basin of the Syuryuktyakh River. The results of this analysis indicate a tendency towards an area decrease in the Bolshaya Momskaya aufeis in recent years, while no reduction in Syuryuktyakh River aufeis area was observed. The combined digital database of the aufeis is available at https://doi.org/10.1594/PANGAEA.891036.</p

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

Gel with Ectoine improves wound healing on a thermal burn model in rats

Due to the ability to create complexes of water molecules on the surface of the mucous membrane, ectoine is a promising compound for the treatment of burns. Evaluate the reparative activity of Ectoine using the thermal burn model in rats. In male rats (n=30), 2 thermal burns were counteracted under counter-anesthesia, one of which was treated by topical application of the test drugs for 7 days, and the other served as a contro