2,465 research outputs found

    Voltammetric optimisation of TEMPO-mediated oxidations at cellulose fabric

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    A simple method for rapid voltammetric screening of N-oxyl based mediators and reaction conditions for electrochemical oxidation of cellulose is described. Using immobilised cellulose (cotton cloth) the screening requires small quantities of mediator and yet yields information about relative efficiency of mediator, optimum pH, and preferred buffer identity.</p

    Phosphorylation Status of RNA Polymerase II Carboxyl-terminal Domain in Porcine Oocytes and Early Embryos

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    Fertilization of the oocyte commences embryogenesis during which maternally inherited mRNAs are degraded and the embryonic genome is activated. Transcription of embryonic mRNA is initiated by embryonic genome activation (EGA). RNA polymerase II (RNA Pol II) is responsible for the synthesis of mRNAs and most small nuclear RNAs, and consists of 12 subunits, the largest of which characteristically harbors a unique C-terminal domain (CTD). Transcriptional activity of RNA Pol II is highly regulated, in particular, by phosphorylation of serine residues in the CTD. Here, we have shown the presence of RNA Pol II CTD phosphoisoforms in porcine oocytes and preimplantation embryos. The distribution pattern as well as phosphorylation dynamics in germinal vesicles and during embryogenesis differed in developmental stages with these isoforms, indicating a role of RNA Pol II CTD phosphorylation at the serine residue in transcriptional activation during both oocyte growth and embryonic genome activation. We additionally examined the effects of the RNA Pol II inhibitor, α-amanitin, on embryo development. Our results show that inhibition of polymerase, even at very early stages and for a short period of time, dramatically impaired blastocyst formation. These findings collectively suggest that the functionality of maternal RNA Pol II, and consequently, expression of early genes regulated by this enzyme are essential for proper embryo development

    TBK1 regulates regeneration of pancreatic β-cells

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    Small-molecule inhibitors of non-canonical IκB kinases TANK-binding kinase 1 (TBK1) and IκB kinase ε (IKKε) have shown to stimulate β-cell regeneration in multiple species. Here we demonstrate that TBK1 is predominantly expressed in β-cells in mammalian islets. Proteomic and transcriptome analyses revealed that genetic silencing of TBK1 increased expression of proteins and genes essential for cell proliferation in INS-1 832/13 rat β-cells. Conversely, TBK1 overexpression decreased sensitivity of β-cells to the elevation of cyclic AMP (cAMP) levels and reduced proliferation of β-cells in a manner dependent on the activity of cAMP-hydrolyzing phosphodiesterase 3 (PDE3). While the mitogenic effect of (E)3-(3-phenylbenzo[c]isoxazol-5-yl)acrylic acid (PIAA) is derived from inhibition of TBK1, PIAA augmented glucose-stimulated insulin secretion (GSIS) and expression of β-cell differentiation and proliferation markers in human embryonic stem cell (hESC)-derived β-cells and human islets. TBK1 expression was increased in β-cells upon diabetogenic insults, including in human type 2 diabetic islets. PIAA enhanced expression of cell cycle control molecules and β-cell differentiation markers upon diabetogenic challenges, and accelerated restoration of functional β-cells in streptozotocin (STZ)-induced diabetic mice. Altogether, these data suggest the critical function of TBK1 as a β-cell autonomous replication barrier and present PIAA as a valid therapeutic strategy augmenting functional β-cells

    Quantification of sulcal emergence timing and its variability in early fetal life: Hemispheric asymmetry and sex difference

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    Human fetal brains show regionally different temporal patterns of sulcal emergence following a regular timeline, which may be associated with spatiotemporal patterns of gene expression among cortical regions. This study aims to quantify the timing of sulcal emergence and its temporal variability across typically developing fetuses by fitting a logistic curve to presence or absence of sulcus. We found that the sulcal emergence started from the central to the temporo-parieto-occipital lobes and frontal lobe, and the temporal variability of emergence in most of the sulci was similar between 1 and 2 weeks. Small variability (\u3c 1 week) was found in the left central and postcentral sulci and larger variability (\u3e2 weeks) was shown in the bilateral occipitotemporal and left superior temporal sulci. The temporal variability showed a positive correlation with the emergence timing that may be associated with differential contributions between genetic and environmental factors. Our statistical analysis revealed that the right superior temporal sulcus emerged earlier than the left. Female fetuses showed a trend of earlier sulcal emergence in the right superior temporal sulcus, lower temporal variability in the right intraparietal sulcus, and higher variability in the right precentral sulcus compared to male fetuses. Our quantitative and statistical approach quantified the temporal patterns of sulcal emergence in detail that can be a reference for assessing the normality of developing fetal gyrification

    Brane-Bulk Interaction and Holographic Principle

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    We introduce the brane-bulk interaction to discuss a limitation of the cosmological Cardy-Verlinde formula which is useful for the holographic description of brane cosmology. In the presence of the brane-bulk interaction, we cannot find the entropy representation of the first Friedmann equation (the cosmological Cardy-Verlinde formula). In the absence of the interaction, the cosmological Cardy-Verlinde formula is established even for the time-dependent charged AdS background. Hence, if there exists a dynamic exchange of energy between the brane and the bulk (that is, if T~t y0\tilde T^t~_y \not=0), we cannot achieve the cosmological holographic principle on the brane.Comment: 9 pages, REVTE
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