641 research outputs found

    Components required for in vitro cleavage and polyadenylation of eukaryotic mRNA

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    We have studied in vitro cleavage/polyadenylation of precursor RNA containing herpes simplex virus type 2 poly A site sequences and have analysed four RNA/protein complexes which form during in vitro reactions. Two complexes, A and B, form extremely rapidly and are then progressively replaced by a third complex, C which is produced following cleavage and polyadenylation of precursor RNA. Substitution of ATP with cordycepin triphosphate prevents polyadenylation and the formation of complex C however a fourth complex, D, results which contains cleaved RNA. A precursor RNA lacking GU-rich downstream sequences required for efficient cleavage/ polyadenylation fails to form complex B and produces a markedly reduced amount of complex A. As these GU-rich sequences are required for efficient cleavage, this establishes a relationship between complex B formation and cleavage/polyadenylation of precursor RNA in vitro. The components required for in vitro RNA processing have been separated by fractionation of the nuclear extract on Q-Sepharose and Biorex 70 columns. A Q-Sepharose fraction forms complex B but does not process RNA. Addition of a Biorex 70 fraction restores cleavage activity at the poly A site but this fraction does not appear to contribute to complex formation. Moreover, in the absence of polyethylene glycol, precursor RNA is not cleaved and polyadenylated, however, complexes A and B readily form. Thus, while complex B is necessary for in vitro cleavage and polyadenylation, it may not contain all the components required for this processing

    Systematic Study of Fermion Masses and Mixing Angles in Horizontal SU(2) Gauge Theory

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    Despite its great success in explaining the basic interactions of nature, the standard model suffers from an inability to explain the observed masses of the fundamental particles and the weak mixing angles between them. We shall survey a set of possible extensions to the standard model, employing an SU(2) ``horizontal'' gauge symmetry between the particle generations, to see what light they can shed on this problem.Comment: 43 pages, 4 figures (available by postal mail on request), OZ-92/0

    How well do we understand the reaction rate of C burning?

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    Carbon burning plays a crucial role in stellar evolution, where this reaction is an important route for the production of heavier elements. A particle-γ coincidence technique that minimizes the backgrounds to which this reaction is subject and provides reliable cross sections has been used at the Argonne National Laboratory to measure fusion cross-sections at deep sub-barrier energies in the 12C+12C system. The corresponding excitation function has been extracted down to a cross section of about 6 nb. This indicates the existence of a broad S-factor maximum for this system. Experimental results are presented and discussed

    Forest Biodiversity Assessment in Peruvian Andean Montane Cloud Forest

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    Cloud forests are unusual and fragile habitats, being one of the least studied and least understood ecosystems. The tropical Andean dominion is considered one of the most significant places in the world as rega rds biological diversity, with a very high level of endemism. The biodiversity was analysed in an isolated remnant area of a tropical montane cloud forest known as the ?Bosque de Neblina de Cuyas?, in the North of the Peruvian Andean range. Composition, structure and dead wood were measured or estimated. The values obtained were compared with other cloud forests. The study revealed a high level of forest biodiversity, although the level of biodiversity differs from one area to another: in the inner areas, where human pressure is almost inexistent, the biodiversity values increase. The high species richness and the low dominance among species bear testimony to this montane cloud forest as a real enclave of biodiversity

    The PHENIX Experiment at RHIC

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    The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

    Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

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    The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

    Genome-wide meta-analysis of myopia and hyperopia provides evidence for replication of 11 loci

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    Refractive error (RE) is a complex, multifactorial disorder characterized by a mismatch between the optical power of the eye and its axial length that causes object images to be focused off the retina. The two major subtypes of RE are myopia (nearsightedness) and hyperopia (farsightedness), which represent opposite ends of the distribution of the quantitative measure of spherical refraction. We performed a fixed effects meta-analysis of genome-wide association results of myopia and hyperopia from 9 studies of European-derived populations: AREDS, KORA, FES, OGP-Talana, MESA, RSI, RSII, RSIII and ERF. One genome-wide significant region was observed for myopia, corresponding to a previously identified myopia locus on 8q12 (p = 1.25610-8), which has been reported by Kiefer et al. as significantly associated with myopia age at onset and Verhoeven et al. as significantly associated to mean spherical-equivalent (MSE) refractive error. We observed two genomewide significant association

    Transglutaminase 2 moderates the expansion of mouse abdominal aortic aneurysms

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    Objective: Previously published work has indicated that transcripts encoding transglutaminase 2 (TG2) increase markedly in a rat model of abdominal aortic aneurysm. This study determines whether TG2 and the related TG, factor XIII-A (FXIII-A), protect against aortic aneurysm development in mice. Methods: C57BL/6J wild-type, Tgm2–/– knockout, F13a1–/– knockout, and Tgm2–/–/F13a1–/– double knockout mice were subjected to laparotomy and periaortic application of CaCl2. Results: Tgm2–/– mice showed slightly greater aortic dilatation at 6 weeks after treatment when compared with wild type. However, vessels from Tgm2–/– mice, but not wild-type mice, continued to dilate up to 6 months after injury and by 24 weeks, a greater number of Tgm2–/– mice had developed aneurysms (16/17 vs 10/19; P = .008). Laparotomy resulted in a high death rate in F13a1–/– knockout mice, more frequently from cardiac complications than from hemorrhage, but among F13a1–/– mice that survived for 6 weeks after CaCl2 treatment, abdominal aortic aneurysm diameter was unaltered relative to wild-type mice. Laparotomy resulted in a higher death rate among Tgm2–/–/F13a1–/– double knockout mice, owing to an increased frequency of delayed bleeding. Surprisingly, Tgm2–/–/F13a1–/– double knockout mice showed a trend toward decreased dilatation of the aorta 6 weeks after injury, and this finding was replicated in Tgm2–/–/F13a1–/– mice subjected to carotid artery injury. Levels of transcripts encoding TG2 were not increased in the aortas of injured wild-type or F13a1–/– knockout mice relative to uninjured mice, although changes in the levels of other transcripts accorded with previous descriptions of the CaCl2 aneurysm model in mice. Conclusions: Knockout of Tgm2, but not F13a1 exacerbates aortic dilatation, suggesting that TG2 confers protection. However, levels of TG2 messenger RNA are not acutely elevated after injury. FXIII-A plays a role in preventing postoperative damage after laparotomy, confirming previous reports that it prevents distal organ damage after trauma. TG2 promotes wound healing after surgery and, in its absence, the bleeding diathesis associated with FXIII-A deficiency is further exposed

    Measurement and Assessment of Grief in a Large International Sample

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    Background: In 2022, the International Classification of Diseases (ICD-11) and an update of the Diagnostic Sta- tistical Manual of Mental Disorders (DSM 5 TR) were released for implementation worldwide and now include the new Prolonged Grief Disorder (PGD). The newest definition of PGD is based on robust clinical research from the Global North yet until now has not been tested for global applicability. Methods: The current study assesses the new PGD ICD-11 criteria in a large international sample of 1393 bereaved adults. The majority of the sample was included from the USА. Additionally, we conduct a sub-sample analysis to evaluate the psychometric properties, probable caseness of PGD, and differences in network structure across three regions of residency (USA, Greece-Cyprus, Turkey-Iran). Results: The psychometric validity and reliability of the 33-item International Prolonged Grief Disorder Scale (IPGDS) were confirmed across the whole sample and for each regional group. Using the strict diagnostic algo- rithm, the probable caseness for PGD for the whole sample was 3.6 %. Probable caseness was highest for the Greece-Cyprus group (6.9 %) followed by Turkey-Iran (3.2 %) and the USA (2.8 %). Finally, the network structure of the IPGDS standard items and cultural supplement items (total of 33 items) confirmed the strong connection between central items of PGD, and revealed unique network connections within the regional groups. Limitations: Future research is encouraged to include larger sample sizes and a more systematic assessment of culture. Conclusion: Overall, our findings confirm the global applicability of the new ICD-11 PGD disorder definition as evaluated through the newly developed IPGDS. This scale includes culturally sensitive grief symptoms that may improve clinical precision and decision-making
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