3,251 research outputs found
Temporal study of natural populations of Heterorhabditid and Steinernematid nematodes in horticultural crop soils
La dynamique des populations de nĂ©matodes entomopathogĂšnes dans des sols horticoles a Ă©tĂ© Ă©tudiĂ©e par des prĂ©lĂšvements mensuels en huit sites de Catalogne (nord-est de l'Espagne) pendant 14 mois. Ces nĂ©matodes entomopathogĂšnes ont Ă©tĂ© dĂ©tectĂ©s dans six des huit sites et ont continuĂ© Ă l'ĂȘtre quels qu'aient Ă©tĂ© les traitements agricoles pratiquĂ©s sur ces sites. Pendant cette Ă©tude, les sites ont Ă©tĂ© labourĂ©s, dĂ©truisant ainsi l'habitat naturel des nĂ©matodes, puis laissĂ©s en jachĂšre pendant plusieurs mois, sans que la prĂ©sence des nĂ©matodes n'en paraisse affectĂ©e. Cependant, une influence saisonniĂšre peut ĂȘtre observĂ©e, la prĂ©sence des nĂ©matodes Ă©tant plus faible pendant les mois d'Ă©tĂ© oĂč la tempĂ©rature est Ă©levĂ©e. Cette influence saisonniĂšre apparaĂźt Ă©galement affecter la rĂ©partition verticale des nĂ©matodes qui migrent vers les couches plus profondes du sol, vraisemblablement pour Ă©viter les effets nĂ©fastes de la tempĂ©rature et du manque d'humiditĂ©. Les rĂ©sultats de cette Ă©tude montrent que les populations naturelles de nĂ©matodes entomopathogĂšnes sont capables de persister et de survivre dans le sol pendant de longues pĂ©riodes en s'adaptant aux conditions fluctuantes et adverses de leur habitat naturel. (RĂ©sumĂ© d'auteur
Size effect in the ionization energy of PAH clusters
We report the first experimental measurement of the near-threshold
photo-ionization spectra of polycyclic aromatic hydrocarbon clusters made of
pyrene C16H10 and coronene C24H12, obtained using imaging photoelectron
photoion coincidence spectrometry with a VUV synchrotron beamline. The
experimental results of the ionization energy are confronted to calculated ones
obtained from simulations using dedicated electronic structure treatment for
large ionized molecular clusters. Experiment and theory consistently find a
decrease of the ionization energy with cluster size. The inclusion of
temperature effects in the simulations leads to a lowering of this energy and
to a quantitative agreement with the experiment. In the case of pyrene, both
theory and experiment show a discontinuity in the IE trend for the hexamer
Merida virus, a putative novel rhabdovirus discovered in Culex and Ochlerotatus spp. mosquitoes in the Yucatan Peninsula of Mexico
Sequences corresponding to a putative, novel rhabdovirus [designated Merida virus (MERDV)] were initially detected in a pool of Culex quinquefasciatus collected in the Yucatan Peninsula of Mexico. The entire genome was sequenced, revealing 11â798ânt and five major ORFs, which encode the nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G) and RNA-dependent RNA polymerase (L). The deduced amino acid sequences of the N, G and L proteins have no more than 24, 38 and 43â% identity, respectively, to the corresponding sequences of all other known rhabdoviruses, whereas those of the P and M proteins have no significant identity with any sequences in GenBank and their identity is only suggested based on their genome position. Using specific reverse transcription-PCR assays established from the genome sequence, 27â571 C. quinquefasciatus which had been sorted in 728 pools were screened to assess the prevalence of MERDV in nature and 25 pools were found positive. The minimal infection rate (calculated as the number of positive mosquito pools per 1000 mosquitoes tested) was 0.9, and similar for both females and males. Screening another 140 pools of 5484 mosquitoes belonging to four other genera identified positive pools of Ochlerotatus spp. mosquitoes, indicating that the host range is not restricted to C. quinquefasciatus. Attempts to isolate MERDV in C6/36 and Vero cells were unsuccessful. In summary, we provide evidence that a previously undescribed rhabdovirus occurs in mosquitoes in Mexico.The authors thank Valeria Bussetti for expert technical assistance. This study was supported by the National Institutes of Health (awards 5R21AI067281, AI057158, 5R21AI067281 and AI088647), the United States Department of Defense and an intramural grant from Iowa State University. AEF is supported by a grant from the Wellcome Trust (award 106207).This is the final version of the article. It first appeared from the Microbiology Society via http://dx.doi.org/10.1099/jgv.0.00042
Merida virus, a putative novel rhabdovirus discovered in Culex and Ochlerotatus spp. mosquitoes in the Yucatan Peninsula of Mexico.
Sequences corresponding to a putative, novel rhabdovirus [designated Merida virus (MERDV)] were initially detected in a pool of Culex quinquefasciatus collected in the Yucatan Peninsula of Mexico. The entire genome was sequenced, revealing 11â798ânt and five major ORFs, which encode the nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G) and RNA-dependent RNA polymerase (L). The deduced amino acid sequences of the N, G and L proteins have no more than 24, 38 and 43â% identity, respectively, to the corresponding sequences of all other known rhabdoviruses, whereas those of the P and M proteins have no significant identity with any sequences in GenBank and their identity is only suggested based on their genome position. Using specific reverse transcription-PCR assays established from the genome sequence, 27â571 C. quinquefasciatus which had been sorted in 728 pools were screened to assess the prevalence of MERDV in nature and 25 pools were found positive. The minimal infection rate (calculated as the number of positive mosquito pools per 1000 mosquitoes tested) was 0.9, and similar for both females and males. Screening another 140 pools of 5484 mosquitoes belonging to four other genera identified positive pools of Ochlerotatus spp. mosquitoes, indicating that the host range is not restricted to C. quinquefasciatus. Attempts to isolate MERDV in C6/36 and Vero cells were unsuccessful. In summary, we provide evidence that a previously undescribed rhabdovirus occurs in mosquitoes in Mexico.The authors thank Valeria Bussetti for expert technical assistance. This study was supported by the National Institutes of Health (awards 5R21AI067281, AI057158, 5R21AI067281 and AI088647), the United States Department of Defense and an intramural grant from Iowa State University. AEF is supported by a grant from the Wellcome Trust (award 106207).This is the final version of the article. It first appeared from the Microbiology Society via http://dx.doi.org/10.1099/jgv.0.00042
Classifying Parkinsonâs Disease Patients With Syntactic and Socio-emotional Verbal Measures
Frontostriatal disorders, such as Parkinsonâs disease (PD), are characterized by progressive disruption of cortico-subcortical dopaminergic loops involved in diverse higher-order domains, including language. Indeed, syntactic and emotional language tasks have emerged as potential biomarkers of frontostriatal disturbances. However, relevant studies and models have typically considered these linguistic dimensions in isolation, overlooking the potential advantages of targeting multidimensional markers. Here, we examined whether patient classification can be improved through the joint assessment of both dimensions using sentential stimuli. We evaluated 31 early PD patients and 24 healthy controls via two syntactic measures (functional-role assignment, parsing of long-distance dependencies) and a verbal task tapping social emotions (envy, Schadenfreude) and compared their classification accuracy when analyzed in isolation and in combination. Complementarily, we replicated our approach to discriminate between patients on and off medication. Results showed that specific measures of each dimension were selectively impaired in PD. In particular, joint analysis of outcomes in functional-role assignment and Schadenfreude improved the classification accuracy of patients and controls, irrespective of their overall cognitive and affective state. These results suggest that multidimensional linguistic assessments may better capture the complexity and multi-functional impact of frontostriatal disruptions, highlighting their potential contributions in the ongoing quest for sensitive markers of PD.Fil: Baez, Sandra. Universidad de los Andes; ColombiaFil: Herrera, Eduar. Universidad Icesi; ColombiaFil: Trujillo, Catalina. Universidad del Valle; ColombiaFil: Cardona, Juan F.. Universidad del Valle; ColombiaFil: Diazgranados, JesĂșs A.. Centro MĂ©dico de AtenciĂłn NeurolĂłgica NeurĂłlogos de Occidente; ColombiaFil: Pino, Mariana. Universidad AutĂłnoma del Caribe; ColombiaFil: Santamaria Garcia, Hernando. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Hospital Universitario San Ignacio; Colombia. Pontificia Universidad Javeriana; ColombiaFil: Ibañez, Agustin Mariano. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad AutĂłnoma del Caribe; Colombia. Universidad de San AndrĂ©s; Argentina. Universidad Adolfo Ibañez; Chile. University of California; Estados UnidosFil: GarcĂa, Adolfo MartĂn. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad de San AndrĂ©s; Argentina. University of California; Estados Unidos. Universidad Catolica de Cuyo. Facultad de Educacion.; Argentin
Structural and Biophysical Characterization of Staphylococcus Aureus SaMazF Shows Conservation of Functional Dynamics
The Staphylococcus aureus genome contains three toxin-antitoxin modules, including one mazEF module, SamazEF. Using an on-column separation protocol we are able to obtain large amounts of wild-type SaMazF toxin. The protein is well-folded and highly resistant against thermal unfolding but aggregates at elevated temperatures. Crystallographic and nuclear magnetic resonance (NMR) solution studies show a well-defined dimer. Differences in structure and dynamics between the X-ray and NMR structural ensembles are found in three loop regions, two of which undergo motions that are of functional relevance. The same segments also show functionally relevant dynamics in the distantly related CcdB family despite divergence of function. NMR chemical shift mapping and analysis of residue conservation in the MazF family suggests a conserved mode for the inhibition of MazF by MazE
Estradiol regulates brown adipose tissue thermogenesis via hypothalamic AMPK
Copyright © 2014 Elsevier Inc. All rights reserved.Peer reviewedPublisher PD
A dual role in regulation and toxicity for the disordered N-terminus of the toxin GraT.
Bacterial toxin-antitoxin (TA) modules are tightly regulated to maintain growth in favorable conditions or growth arrest during stress. A typical regulatory strategy involves the antitoxin binding and repressing its own promoter while the toxin often acts as a co-repressor. Here we show that Pseudomonas putida graTA-encoded antitoxin GraA and toxin GraT differ from other TA proteins in the sense that not the antitoxin but the toxin possesses a flexible region. GraA auto-represses the graTA promoter: two GraA dimers bind cooperatively at opposite sides of the operator sequence. Contrary to other TA modules, GraT is a de-repressor of the graTA promoter as its N-terminal disordered segment prevents the binding of the GraT2A2 complex to the operator. Removal of this region restores operator binding and abrogates Gr aT toxicity. GraTA represents a TA module where a flexible region in the toxin rather than in the antitoxin controls operon expression and toxin activity
Phosphorylation decelerates conformational dynamics in bacterial translation elongation factors
Bacterial protein synthesis is intricately connected to metabolic rate. One of the ways in which bacteria respond to environmental stress is through posttranslational modifications of translation factors. Translation elongation factor Tu (EF-Tu) is methylated and phosphorylated in response to nutrient starvation upon entering stationary phase, and its phosphorylation is a crucial step in the pathway toward sporulation. We analyze how phosphorylation leads to inactivation of Escherichia coli EF-Tu. We provide structural and biophysical evidence that phosphorylation of EF-Tu at T382 acts as an efficient switch that turns off protein synthesis by decoupling nucleotide binding from the EF-Tu conformational cycle. Direct modifications of the EF-Tu switch I region or modifications in other regions stabilizing the ÎČ-hairpin state of switch I result in an effective allosteric trap that restricts the normal dynamics of EF-Tu and enables the evasion of the control exerted by nucleotides on G proteins. These results highlight stabilization of a phosphorylation-induced conformational trap as an essential mechanism for phosphoregulation of bacterial translation and metabolism. We propose that this mechanism may lead to the multisite phosphorylation state observed during dormancy and stationary phase
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