Low Sugar Is Not Always Good: Impact of Specific O-Glycan Defects on Tip Growth in Arabidopsis

Mutants of the O-glycosylation pathway of extensins as well as molecular dynamics simulations uncover the effects of the O-glycosylation machinery on root hair tip growth

Characterization of JBURE-IIb isoform of Canavalia ensiformis (L.) DC urease.

Ureases, nickel-dependent enzymes that catalyze the hydrolysis of urea into ammonia and bicarbonate, are widespread in plants, bacteria, and fungi. Previously, we cloned a cDNA encoding a Canavalia ensiformis urease isoform named JBURE-II, corresponding to a putative smaller urease protein (78 kDa) when compared to other plant ureases. Aiming to produce the recombinant protein, we obtained jbure-IIb, with different 3? and 5? ends, encoding a 90 kDa urease. Three peptides unique to the JBURE-II/-IIb protein were detected by mass spectrometry in seed extracts, indicating that jbure-II/-IIb is a functional gene. Comparative modeling indicates that JBURE-IIb urease has an overall shape almost identical to C. ensiformis major urease JBURE-I with all residues critical for urease activity. The cDNA was cloned into the pET101 vector and the recombinant protein was produced in Escherichia coli. The JBURE-IIb protein, although enzymatically inactive presumably due to the absence of Ni atoms in its active site, impaired the growth of a phytopathogenic fungus and showed entomotoxic properties, inhibiting diuresis of Rhodnius prolixus isolated Malpighian tubules, in concentrations similar to those reported for JBURE-I and canatoxin. The antifungal and entomotoxic properties of the recombinant JBURE-IIb apourease are consistent with a protective role of ureases in plants

The behavior of larval zebrafish reveals stressor-mediated anorexia during early vertebrate development

The relationship between stress and food consumption has been well documented in adults but less so in developing vertebrates. Here we demonstrate that an encounter with a stressor can suppress food consumption in larval zebrafish. Furthermore, we provide indication that food intake suppression cannot be accounted for by changes in locomotion, oxygen consumption and visual responses, as they remain unaffected after exposure to a potent stressor. We also show that feeding reoccurs when basal levels of cortisol (stress hormone in humans and teleosts) are re-established. The results present evidence that the onset of stress can switch off the drive for feeding very early in vertebrate development, and add a novel endpoint for analyses of metabolic and behavioral disorders in an organism suitable for high-throughput genetics and non-invasive brain imaging

Opposite Effects of HIV-1 p17 Variants on PTEN Activation and Cell Growth in B Cells

The HIV-1 matrix protein p17 is a structural protein that can act in the extracellular environment to deregulate several functions of immune cells, through the interaction of its NH2-terminal region with a cellular surface receptor (p17R). The intracellular events triggered by p17/p17R interaction have been not completely characterized yet. In this study we analyze the signal transduction pathways induced by p17/p17R interaction and show that in Raji cells, a human B cell line stably expressing p17R on its surface, p17 induces a transient activation of the transcriptional factor AP-1. Moreover, it was found to upregulate pERK1/2 and downregulate pAkt, which are the major intracellular signalling components involved in AP-1 activation. These effects are mediated by the COOH-terminal region of p17, which displays the capability of keeping PTEN, a phosphatase that regulates the PI3K/Akt pathway, in an active state through the serin/threonin (Ser/Thr) kinase ROCK. Indeed, the COOH-terminal truncated form of p17 (p17Δ36) induced activation of the PI3K/Akt pathway by maintaining PTEN in an inactive phosphorylated form. Interestingly, we show that among different p17s, a variant derived from a Ugandan HIV-1 strain, named S75X, triggers an activation of PI3K/Akt signalling pathway, and leads to an increased B cell proliferation and malignant transformation. In summary, this study shows the role of the COOH-terminal region in modulating the p17 signalling pathways so highlighting the complexity of p17 binding to and signalling through its receptor(s). Moreover, it provides the first evidence on the presence of a p17 natural variant mimicking the p17Δ36-induced signalling in B cells and displaying the capacity of promoting B cell growth and tumorigenesis

HIV-1 matrix protein p17 misfolding forms toxic amyloidogenic assemblies that induce neurocognitive disorders

© 2017 The Author(s). Human immunodeficiency virus type-1 (HIV-1)-Associated neurocognitive disorder (HAND) remains an important neurological manifestation that adversely affects a patient's quality of life. HIV-1 matrix protein p17 (p17) has been detected in autoptic brain tissue of HAND individuals who presented early with severe AIDS encephalopathy. We hypothesised that the ability of p17 to misfold may result in the generation of toxic assemblies in the brain and may be relevant for HAND pathogenesis. A multidisciplinary integrated approach has been applied to determine the ability of p17 to form soluble amyloidogenic assemblies in vitro. To provide new information into the potential pathogenic role of soluble p17 species in HAND, their toxicological capability was evaluated in vivo. In C. elegans, capable of recognising toxic assemblies of amyloidogenic proteins, p17 induces a specific toxic effect which can be counteracted by tetracyclines, drugs able to hinder the formation of large oligomers and consequently amyloid fibrils. The intrahippocampal injection of p17 in mice reduces their cognitive function and induces behavioral deficiencies. These findings offer a new way of thinking about the possible cause of neurodegeneration in HIV-1-seropositive patients, which engages the ability of p17 to form soluble toxic assemblies

Alkaloids from Hippeastrum morelianum Lem. (Amaryllidaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The Amaryllidaceae family has proven to be a rich source of active molecules. As part of an ongoing project, we report a phytochemical study of Hippeastrum morelianum (Amaryllidaceae), from which we have isolated two homolycorine-type alkaloids, the new 2 alpha,7-dimethoxyhomolycorine (1) and the poorly described candimine (2), as well as six known alkaloids: tazettine, pretazettine, 3-epimacronine, haemanthamine, hamayne and trisphaeridine. For reference purposes, the NMR of the isolated compounds was unequivocally described, based on 2D NMR measurements including H-1-H-1 COSY, H-1-H-1 NOESY, HSQC and HMBC. Copyright (C) 2011 John Wiley & Sons, Ltd.4910668672Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Generalitat de Catalunya [2009-SGR 1060]Agencia Espanola de Cooperacion Internacional para el Desarollo (BECAS-MAEC-AECID)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CAPES [477348/2008-4]CNPq [476616/2006-9]Generalitat de Catalunya [2009-SGR 1060]CNPq [310364/2006-0, 307814/2009-2