325 research outputs found
The translocation of transportin–cargo complexes through nuclear pores is independent of both Ran and energy.
AbstractActive transport between nucleus and cytoplasm proceeds through nuclear pore complexes (NPCs) and is mediated largely by shuttling transport receptors that use direct RanGTP binding to coordinate loading and unloading of cargo [1–4]. Import receptors such as importin β or transportin bind their substrates at low RanGTP levels in the cytoplasm and release them upon encountering RanGTP in the nucleus, where a high RanGTP concentration is predicted. This substrate release is, in the case of import by the importin α/β heterodimer, coupled directly to importin β release from the NPCs. If the importin β –RanGTP interaction is prevented, import intermediates arrest at the nuclear side of the NPCs [5,6]. This arrest makes it difficult to probe directly the Ran and energy requirements of the actual translocation from the cytoplasmic to the nuclear side of the NPC, which immediately precedes substrate release. Here, we have shown that in the case of transportin, dissociation of transportin–substrate complexes is uncoupled from transportin release from NPCs. This allowed us to dissect the requirements of translocation through the NPC, substrate release and transportin recycling. Surprisingly, translocation of transportin–substrate complexes into the nucleus requires neither Ran nor nucleoside triphosphates (NTPs). It is only nuclear RanGTP, not GTP hydrolysis, that is needed for dissociation of transportin–substrate complexes and for re-export of transportin to the cytoplasm. GTP hydrolysis is apparently required only to restore the import competence of the re-exported transportin and, thus, for multiple rounds of transportin-dependent import. In addition, we provide evidence that at least one type of substrate can also complete NPC passage mediated by importin β independently of Ran and energy
Phenomenon of Transfiguration and System of Motifs in I. S. Shmelev’s Story “The Kulikovo Field”
The article presents an analysis of motives that permeate the narrative in the story by Ivan Shmelev “The Kulikovo Field.” The author identified a number of motives, which semantics and functioning is interpreted at subject-figurative, symbolic, thematic levels of the narrative. Special attention is paid to the phenomenon of transfiguration. It is proved that it became a core of the motif field of the story. The author believes that this motive is a mean of contamination, on the one hand, of the dominant motive of trial-overcome, on the other hand, of the complex of motives of fear, signs and lights. The interaction of the structural motifs of the way-meeting and cross is noted. The question is raised about the specifics of the philosophical and aesthetic position of the writer, about the specifics of his perception of the Orthodox doctrine. Novelty of research consists in the fact that the conceptual significance of biblical image of “shear” (“remainder”), that is, the teachings of Isaiah about the trials of the people, coming deliverance and the righteous for Shmelev is revealed for the first time. It appears that the implementation of these images constructed argument number in the story. Understanding the role of Sergius of Radonezh, whose feat was an example of asceticism and the revival of the moral sense of the people, reflects the number of historiosophical ideas of the writer, above all one of the fundamental positions of Shmelev’s anthropology: the historical transformation of Russia precedes the spiritual transformation of man. In this process the key role the writer takes of the intelligentsia, who should return to the Orthodox roots, recognising their new task
First systematic high-precision survey of bright supernovae
Rapid variability before and near the maximum brightness of supernovae has the potential to provide a better understanding of nearly every aspect of supernovae, from the physics of the explosion up to their progenitors and the circumstellar environment. Thanks to modern time-domain optical surveys, which are discovering supernovae in the early stage of their evolution, we have the unique opportunity to capture their intraday behavior before maximum. We present high-cadence photometric monitoring (on the order of seconds-minutes) of the optical light curves of three Type Ia and two Type II SNe over several nights before and near maximum light, using the fast imagers available on the 2.3 m Aristarchos telescope at Helmos Observatory and the 1.2 m telescope at Kryoneri Observatory in Greece. We applied differential aperture photometry techniques using optimal apertures and we present reconstructed light curves after implementing a seeing correction and the Trend Filtering Algorithm (TFA, Kovács et al. 2005, MNRAS, 356, 557). TFA yielded the best results, achieving a typical precision between 0.01 and 0.04 mag. We did not detect significant bumps with amplitudes greater than 0.05 mag in any of the SNe targets in the VR-, R-, and I-bands light curves obtained. We measured the intraday slope for each light curve, which ranges between −0.37−0.36 mag day−1 in broadband VR, −0.19−0.31 mag day−1 in R band, and −0.13−0.10 mag day−1 in I band. We used SNe light curve fitting templates for SN 2018gv, SN 2018hgc and SN 2018hhn to photometrically classify the light curves and to calculate the time of maximum. We provide values for the maximum of SN 2018zd after applying a low-order polynomial fit and SN 2018hhn for the first time. We conclude that optimal aperture photometry in combination with TFA provides the highest-precision light curves for SNe that are relatively well separated from the centers of their host galaxies. This work aims to inspire the use of ground-based, high-cadence and high-precision photometry to study SNe with the purpose of revealing clues and properties of the explosion environment of both core-collapse and Type Ia supernovae, the explosion mechanisms, binary star interaction and progenitor channels. We suggest monitoring early supernovae light curves in hotter (bluer) bands with a cadence of hours as a promising way of investigating the post-explosion photometric behavior of the progenitor stars
Surveillance of Bisphenol A and Phthalates in Materials in Contact with Food and Children Toys in Cyprus
In recent years a variety of chemicals have been found to disrupt the endocrine systems, and there is strong evidence that chemical exposure has been associated with adverse developmental and reproductive effects on fish and wildlife in particular locations. Bisphenol A (BPA) is one of a number of chemicals that may have the potential to interact with hormone systems in the body. BPA is an organic compound with two phenol functional groups used to make polycarbonate plastic and epoxy resins, along with other applications. Another class of chemicals are the phthalate esters and are mainly used as plasticizers (substances added to plastics to increase their flexibility, transparency, durability, and longevity). They are used primarily to soften PVC used in soft children toys
Long-Term Outdoor Testing of Perovskite Mini-Modules: Effects of FACl Additives
The outdoor performance monitoring of perovskite modules over 16 weeks is reported. Two different types of active perovskite layers were studied: one type contained formamidinium chloride (FACl) halide additives and the other contained no additives with the main purpose to investigate performance trends during the outdoor exposure of those type of devices. Long-term side-by-side outdoor testing of devices with and without halide additives was not implemented in the past and merits investigation in order to determine the impact of additives on perovskite performance and stability. Although the two types of modules displayed similar initial outdoor performance characteristics, their outdoor performance evolution differed. Different degradation rates between the modules with and without additives were obtained just after field installation. In particular, the modules with additives exhibited higher performance degradation under open-circuit loading conditions between current-voltage (IV) scans. Long-term monitoring of both modules recorded a reduction of the efficiency over the course of the day with subsequent recovery overnight and in many cases during the day. The relative values of performance degradation and overnight recovery were calculated over the timespan of outdoor testing and indicated dominant normalized diurnal performance degradation in one type of modules (without FACl additives) in the range between 15–20% and in the other type of modules (with additives) 5–10%. The dominant normalized performance recovery values found were 25–30% and 5–10%, respectively. Finally, dark lock-in thermography (DLIT) and Raman studies were performed on the exposed devices and revealed differences in hotspot evolution and vibrational modes between the different types of module
How to tie dangerous surgical knots: easily. Can we avoid this?
ObjectiveSecure knots are essential in all areas of surgical, medical and veterinary practice. Our hypothesis was that technique of formation of each layer of a surgical knot was important to its security.DesignEqual numbers of knots were tied, by each of three groups, using three techniques, for each of four suture materials; a standard flat reef knot (FRK), knots tied under tension (TK) and knots laid without appropriate hand crossing (NHCK). Each knot technique was performed reproducibly, and tested by distraction with increasing force, till each material broke or the knot separated completely.SettingTemporary knot tying laboratory.MaterialsThe suture materials were, 2/0 polyglactin 910 (Vicryl), 3/0 polydioxanone, 4/0 poliglecaprone 25 (Monocryl) and 1 nylon (Ethilon).ParticipantsThree groups comprised, a senior surgeon, a resident surgeon and three medical students.Outcome measuresProportion of each knot type that slipped, degree of slippage and length of suture held in loop secured by each knot type.Results20% of FRK tied with all suture materials slipped; all knots tied with the other two techniques, with all materials, slipped, TK (100%) and NHCK (100%). The quantitative degree of slip was significantly less for FRK (mean 6.3%–, 95% CI 2.2% to 10.4%) than for TK (mean 312%, 95% CI 280.0% to 344.0%) and NHCK (mean 113.0%, –95% CI 94.3% to 131.0%).The mean length of suture in loops held within (FRK mean 25.1 mm 95% CI 24.2 to 26.0 mm) was significantly greater than mean lengths held by the other techniques (TK mean 17.0 mm, 95% CI 16.3 to 17.7 mm), (NHCK mean 16.3 mm, 95% CI 15.9 to 16.7 mm). The latter two types of knot may have tightened more than anticipated, in comparison to FRK, with potential undue tissue tension.ConclusionMeticulous technique of knot tying is essential for secure knots, appropriate tissue tension and the security of anastomoses and haemostasis effected.</jats:sec
Progression of familial adenomatous polyposis (FAP) colonic cells after transfer of the src or polyoma middle T oncogenes: cooperation between src and HGF/Met in invasion.
Little is known about the the signalling pathways driving the adenoma-to-carcinoma sequence in human colonic epithelial cells. Accumulation and activation of the src tyrosine kinase in colon cancer suggest a potential role of this oncogene in this early progression. Therefore, we introduced either activated src (m-src), polyoma-MT alone or combined with normal c-src in the adenoma PC/AA/C1 cell line (PC) to define the function and phenotypic transformations induced by these oncogenes in familial adenomatous polyposis (FAP) colonic epithelial cells. Functional expression of these oncoproteins induced the adenoma-to-carcinoma conversion, overexpression of the hepatocyte growth factor (HGF) receptor Met, but failed to confer invasiveness in vivo and in vitro, or to produce alterations in cell proliferation and differentiation. In contrast, PC-msrc cells became susceptible to the HGF-induced invasion of collagen gels and exhibited sustained activation of the pp60src tyrosine kinase and Tyr phosphorylation of the 120-kDa E-cadherin, which was further increased by HGF Transcripts of HGF were clearly identified by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot in the parental and transformed PC cells, suggesting an autocrine mechanism. Taken together, the data indicate that: (1) experimental activation of src and PyMT pathways directly induces tumorigenicity and Met upregulation in a colon adenoma cell line; (2) HGF-activated Met and src cooperate in inducing invasion; (3) in view of the molecular associations between catenins and cadherin or the tumour-suppressor gene product APC, the cell adhesion molecule E-cadherin may constitute a downstream effector of src and Met
- …