242 research outputs found

    Simultaneous local resolution along a rational valuation in two dimensional positive characteristic function fields

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    We consider the condition that a germ of an algebraic mapping of nonsingular surfaces can be made finite, after sufficient blowing up along a nondiscrete rational rank 1 valuation. This problem has been solved in the affirmative in characteristic zero by Abhyankar. He calls this simultaneous resolution. The essential new case that occurs in positive characteristic p is a chain of Artin-Schreier extensions. It is known that simultaneous local resolution is true (along a nondiscrete rational rank 1 valuation) for a single Artin-Schreier extension. We prove that simultaneous local resolution is true in a tower of two Artin-Schreier extensions.Includes bibliographical references

    Identification of a novel nucleolin related protein (NRP) gene expressed during rat spermatogenesis

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    <p>Abstract</p> <p>Background</p> <p>Nucleolin is a major nucleolar phosphoprotein involved in various steps of ribosome biogenesis in eukaryotic cells. As nucleolin plays a significant role in ribosomal RNA transcription we were interested in examining in detail the expression of nucleolin across different stages of spermatogenesis and correlate with the transcription status of ribosomal DNA in germ cells.</p> <p>Results</p> <p>By RT PCR and western blot analysis we found that nucleolin is strongly down regulated in meiotic spermatocytes and haploid germ cells. We have identified a new nucleolin related protein (NRP) gene in the rat genome, which is over expressed in the testis and is up regulated several fold in meiotic spermatocytes and haploid germ cells. The NRP protein lacks the acidic stretches in its N terminal domain, and it is encoded in rat chromosome 15 having a different genomic organization as compared to nucleolin gene present on chromosome 9. We have also found NRP genes encoded in genomes of other mammalian species. We performed run-on transcription assay where we have observed that rDNA is transcribed at much lower level in meiotic spermatocytes and haploid spermatids as compared to diploid cells. By siRNA knock down experiments we could also demonstrate that NRP can support rDNA transcription in the absence of nucleolin.</p> <p>Conclusion</p> <p>We have identified a new nucleolin variant over expressed in germ cells in rat and analyzed its domain structure. We attribute that the transcriptional activity of rDNA genes in the late spermatogenesis is due to the presence of this variant NRP. The expression of this variant in the germ cells in the absence of nucleolin, could have additional functions in the mammalian spermatogenesis which needs to be investigated further.</p

    Propolis Modulates Inflammatory Mediators and Improves Histopathology in Male Rats with L-arginine-induced Acute Pancreatitis

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    ABSTRACT: Objectives: This study aimed to determine the effects of propolis on immune mediators and tissue histopathology in rats with L-arginine-induced acute pancreatitis (AP). Methods: This study was conducted at Imam Abdulrahman Bin Faisal University, Dammam, Saudia Arabia between September and November 2017. A total of 24 male albino Wistar rats were divided into three equal groups. Group one was the negative control, group two was the positive control (L-arginine-induced AP) and group three received treatment (L-arginineinduced AP and propolis). The rats in group three were treated with 100 mg/kg propolis for seven days after AP induction. Pancreatic tissue was evaluated histologically and levels of interleukin (IL)-6, IL-22 and IL-1β and tumour necrosis factor-alpha (TNF-α) were measured. Results: Propolis reduced the quanitity of proinflammatory molecules (TNF-α, IL-1β and IL-6) in group three compared to group two, significantly increased the overall anti-inflammatory effect of IL-22 (P &lt;0.005) and reduced interstitial inflammation and neutrophil cell infiltration of the pancreatic tissues. Conclusion: Propolis may exert a therapeutic effect in AP. Further studies are required to demonstrate the mechanisms of propolis in AP.Keywords: Propolis; Arginine; Pancreatitis; Interleukins; Cytokinesis; Rats; Saudi Arabia

    Chromatin architecture reorganisation during neuronal cell differentiation in Drosophila genome

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    The organization of the genome into topologically associating domains (TADs) was shown to have a regulatory role in development and cellular functioning, but the mechanism involved in TAD establishment is still unclear. Here, we presented the first high-resolution contact map of Drosophila neuronal cells (BG3) and identified different classes of TADs by comparing this to genome organization in embryonic cells (Kc167). We find that only some TADs are conserved in both cell lines, whereas the rest are cell-specific TADs. This is supported by a change in the enrichment of architectural proteins at TAD borders, with BEAF-32 present in embryonic cells and CTCF in neuronal cells. Furthermore, we observed strong divergent transcription, together with RNA Polymerase II occupancy, and an increase in DNA accessibility at the TAD borders. TAD borders that are specific to neuronal cells are enriched in enhancers controlled by neuronal-specific transcription factors. Our results suggest that TADs are dynamic across developmental stages and reflect the interplay between insulators, transcriptional states and enhancer activities

    INTERNET BEHAVIOUR PATTERN IN UNDERGRADUATE MEDICAL STUDENTS IN MANGALORE

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    Abstract: Considering the explosive growth in internet use among medical students in India, this study aimed to determine the prevalence of internet addiction in undergraduate medical students.This cross-sectional study involved 90 subjects (18-20 years of age) selected by random sampling from the first year undergraduate medical student population at Kasturba Medical College Mangalore. Young&apos;s Internet addiction test questionnaire was administered. Based on the scoring, subjects were classified into normal users (score &lt;20), mild (score 20-49), moderate (score 50-79) and severe (score &gt;79) internet addiction groups.The prevalence of internet addiction (moderate and severe) was determined to be 18.88%. Majority (57.77%) conformed to mild addiction. The most common purpose for internet use was found to be social networking (97.8%), followed closely by e mailing (87.8%).The prevalence of moderate to severe internet addiction appeared to be low, a significant number of students conform to mild addiction

    Dying mRNA Tells a Story of Its Life

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    In this issue of Cell, Pelechano et al. report that sequencing of mRNA decay intermediates shows surprisingly tight coupling of a major decay pathway to the movement of the last translating ribosome, revealing stress- and starvation-dependent modulation of translation elongation

    A splicing-dependent transcriptional checkpoint associated with prespliceosome formation

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    There is good evidence for functional interactions between splicing and transcription in eukaryotes, but how and why these processes are coupled remain unknown. Prp5 protein (Prp5p) is an RNA-stimulated adenosine triphosphatase (ATPase) required for prespliceosome formation in yeast. We demonstrate through in vivo RNA labeling that, in addition to a splicing defect, the prp5-1 mutation causes a defect in the transcription of intron-containing genes. We present chromatin immunoprecipitation evidence for a transcriptional elongation defect in which RNA polymerase that is phosphorylated at Ser5 of the largest subunit’s heptad repeat accumulates over introns and that this defect requires Cus2 protein. A similar accumulation of polymerase was observed when prespliceosome formation was blocked by a mutation in U2 snRNA. These results indicate the existence of a transcriptional elongation checkpoint that is associated with prespliceosome formation during cotranscriptional spliceosome assembly. We propose a role for Cus2p as a potential checkpoint factor in transcription

    Mobile augmented reality based 3D snapshots

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    We describe a mobile augmented reality application that is based on 3D snapshotting using multiple photographs. Optical square markers provide the anchor for reconstructed virtual objects in the scene. A novel approach based on pixel flow highly improves tracking performance. This dual tracking approach also allows for a new single-button user interface metaphor for moving virtual objects in the scene. The development of the AR viewer was accompanied by user studies confirming the chosen approach
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