Ribonuclease-mediated control of body fat

Obesity is a global health issue, arousing interest in molecular mechanisms controlling fat. Transcriptional regulation of fat has received much attention, and key transcription factors involved in lipid metabolism, such as SBP-1/SREBP, LPD-2/C/EBP, and MDT-15, are conserved from nematodes to mammals. However, there is a growing awareness that lipid metabolism can also be controlled by post-transcriptional mechanisms. Here, we show that the Caenorhabditis elegans RNase, REGE-1, related to MCPIP1/Zc3h12a/Regnase-1, a key regulator of mammalian innate immunity, promotes accumulation of body fat. Using exon-intron split analysis, we find that REGE-1 promotes fat by degrading the mRNA encoding ETS-4, a fat-loss-promoting transcription factor. Because ETS-4, in turn, induces rege-1 transcription, REGE-1 and ETS-4 appear to form an auto-regulatory module. We propose that this type of fat regulation may be of key importance when, if faced with an environmental change, an animal must rapidly but precisely remodel its metabolism.</p

Apple 1-aminocyclopropane-1-carboxylate synthase in complex with the inhibitor L-aminoethoxyvinylglycine: Evidence for a ketimine intermediate

The 1.6-Å crystal structure of the covalent ketimine complex of apple 1-aminocyclopropane-1-carboxylate (ACC) synthase with the potent inhibitor L-aminoethoxyvinylglycine (AVG) is described. ACC synthase catalyzes the committed step in the biosynthesis of ethylene, a plant hormone that is responsible for the initiation of fruit ripening and for regulating many other developmental processes. AVG is widely used in plant physiology studies to inhibit the activity of ACC synthase. The structural assignment is supported by the fact that the complex absorbs maximally at 341 nm. These results are not in accord with the recently reported crystal structure of the tomato ACC synthase AVG complex, which claims that the inhibitor only associates noncovalently. The rate constant for the association of AVG with apple ACC synthase was determined by stopped-flow spectrophotometry (2.1 × 105 M-1 s-1) and by the rate of loss of enzyme activity (1.1 × 105 M-1 s-1). The dissociation rate constant determined by activity recovery is 2.4 × 10-6 s-1. Thus, the calculated Kd value is 10-20 pM

Selective electrodeposition of indium microstructures on silicon and their conversion into InAs and InSb semiconductors

Abstract: The idea of benefitting from the properties of III-V semiconductors and silicon on the same substrate has been occupying the minds of scientists for several years. Although the principle of III-V integration on a silicon-based platform is simple, it is often challenging to perform due to demanding requirements for sample preparation rising from a mismatch in physical properties between those semiconductor groups (e.g. different lattice constants and thermal expansion coefficients), high cost of device-grade materials formation and their post-processing. In this paper, we demonstrate the deposition of group-III metal and III-V semiconductors in microfabricated template structures on silicon as a strategy for heterogeneous device integration on Si. The metal (indium) is selectively electrodeposited in a 2-electrode galvanostatic configuration with the working electrode (WE) located in each template, resulting in well-defined In structures of high purity. The semiconductors InAs and InSb are obtained by vapour phase diffusion of the corresponding group-V element (As, Sb) into the liquified In confined in the template. We discuss in detail the morphological and structural characterization of the synthesized In, InAs and InSb crystals as well as chemical analysis through scanning electron microscopy (SEM), scanning transmission electron microscopy (TEM/STEM), and energy-dispersive X-ray spectroscopy (EDX). The proposed integration path combines the advantage of the mature top-down lithography technology to define device geometries and employs economic electrodeposition (ED) and vapour phase processes to directly integrate difficult-to-process materials on a silicon platform. Graphical abstract: [Figure not available: see fulltext.]

A Rheological Model for Cupuassu (Theobroma grandiflorum) Pulp at Different Concentrations and Temperatures

This work was made aiming at studying the best model for the rheological properties of Cupuassu (Theobroma grandiflorum, Schum) pulps with 14 (in nature), 17, 19, 23 and 25°Brix of total soluble solids (TSS) which were me asured at 20, 30, 40, 50 and 60°C temperature using a conc entric cylinder rheometer. The results were adjusted to the following nine models: Ostwald-de-Waele (power law), Bingham, Casson, Generalized Casson, Heinz–Casson, Herschel–Bulkley, Mizrahi–Berk, Schulmann–Haroske–Reher and Windhab. The parameters of the best model were correlated with pulp temperature and TSS by polynomial regression analysis and were kept in the regression equation only those parameters that contributed more than 1% to the variation of the independent variable. The results indicate that the rheological behavior of Cupuassu pulp in different concentrations and temperatures can be modeled by the Windhab model, although other models can be used in a narrower band of shear stress

Structural basis and function of XRN2 binding by XTB domains

The ribonuclease XRN2 is an essential player in RNA metabolism. In Caenorhabditis elegans, XRN2 functions with PAXT-1, which shares a putative XRN2-binding domain (XTBD) with otherwise unrelated mammalian proteins. Here, we characterize structure and function of an XTBD – XRN2 complex. Although XTBD stably interconnects two XRN2 domains through numerous interacting residues, mutation of a single critical residue suffices to disrupt XTBD – XRN2 complexes in vitro, and recapitulates paxt-1 null mutant phenotypes in vivo. Demonstrating conservation of function, vertebrate XTBD-containing proteins bind XRN2 in vitro, and human CDKN2AIPNL (C2AIL) can substitute for PAXT-1 in vivo. In vertebrates, where three distinct XTBD-containing proteins exist, XRN2 may partition to distinct stable heterodimeric complexes, likely differing in subcellular localization or function. In C. elegans, complex formation with the unique PAXT-1 serves to preserve the stability of XRN2 in the absence of substrate