197 research outputs found
An Aminocaprolactam Racemase from Ochrobactrum anthropi with Promiscuous Amino Acid Ester Racemase Activity
The kinetic resolution of amino acid esters (AAEs) is a useful synthetic strategy for the preparation of single enantiomer amino acids. The development of an enzymatic dynamic kinetic resolution (DKR) process for AAEs, which would give a theoretical yield of 100% of the enantiopure product, would require an amino acid ester racemase (AAER), however, no such enzyme has been described. We have identified low AAER activity of 15 U mg-1 in a homolog of a PLP-dependent α-amino ε-caprolactam racemase (ACLR) from Ochrobactrum anthropi. We have determined the structure of this enzyme, OaACLR, to a resolution of 1.87 Å and using structure-guided saturation mutagenesis, in combination with a colorimetric screen for AAER activity, we have identified a mutant, L293C, in which the promiscuous AAER activity of this enzyme towards L-phenylalanine methyl ester is improved 3.7 fold
The sequence of a male-specific genome region containing the sex determination switch in Aedes aegypti
Aedes aegypti is the principal vector of several important arboviruses. Among the methods of vector control to limit transmission of disease are genetic strategies that involve the release of sterile or genetically modified non-biting males, which has generated interest in manipulating mosquito sex ratios. Sex determination in Ae. aegypti is controlled by a non-recombining Y chromosome-like region called the M locus, yet characterisation of this locus has been thwarted by the repetitive nature of the genome. In 2015, an M locus gene named Nix was identified that displays the qualities of a sex determination switch. With the use of a whole-genome BAC library, we amplified and sequenced a ~200kb region containing this male-determining gene. In this study, we show that Nix is comprised of two exons separated by a 99kb intron, making it an unusually large gene. The intron sequence is highly repetitive and exhibits features in common with old Y chromosomes, and we speculate that the lack of recombination at the M locus has allowed the expansion of repeats in a manner characteristic of a sex-limited chromosome, in accordance with proposed models of sex chromosome evolution in insects
Promoting physical activity in a multi-ethnic population at high risk of diabetes: the 48-month PROPELS randomised controlled trial.
BackgroundPhysical activity is associated with a reduced risk of type 2 diabetes and cardiovascular disease but limited evidence exists for the sustained promotion of increased physical activity within diabetes prevention trials. The aim of the study was to investigate the long-term effectiveness of the Walking Away programme, an established group-based behavioural physical activity intervention with pedometer use, when delivered alone or with a supporting mHealth intervention.MethodsThose at risk of diabetes (nondiabetic hyperglycaemia) were recruited from primary care, 2013-2015, and randomised to (1) Control (information leaflet); (2) Walking Away (WA), a structured group education session followed by annual group-based support; or (3) Walking Away Plus (WAP), comprising WA annual group-based support and an mHealth intervention delivering tailored text messages supported by telephone calls. Follow-up was conducted at 12 and 48 months. The primary outcome was accelerometer measured ambulatory activity (steps/day). Change in primary outcome was analysed using analysis of covariance with adjustment for baseline, randomisation and stratification variables.ResultsOne thousand three hundred sixty-six individuals were randomised (median age = 61 years, ambulatory activity = 6638 steps/day, women = 49%, ethnic minorities = 28%). Accelerometer data were available for 1017 (74%) individuals at 12 months and 993 (73%) at 48 months. At 12 months, WAP increased their ambulatory activity by 547 (97.5% CI 211, 882) steps/day compared to control and were 1.61 (97.5% CI 1.05, 2.45) times more likely to achieve 150 min/week of moderate-to-vigorous physical activity. Differences were not maintained at 48 months. WA was no different to control at 12 or 48 months. Secondary anthropometric and health outcomes were largely unaltered in both intervention groups apart from small reductions in body weight in WA (~ 1 kg) at 12- and 48-month follow-up.ConclusionsCombining a pragmatic group-based intervention with text messaging and telephone support resulted in modest changes to physical activity at 12 months, but changes were not maintained at 48 months.Trial registrationISRCTN 83465245 (registered on 14 June 2012)
Avid binding by B cells to the Plasmodium circumsporozoite protein repeat suppresses responses to protective subdominant epitopes
Antibodies targeting the NANP/NVDP repeat domain of the Plasmodium falciparum circumsporozoite protein (CSP ) can protect against malaria. However, it has also been suggested that the CSP is a decoy that prevents the immune system from mounting responses against other domains of CSP. Here, we show that, following parasite immunization, B cell responses to the CSP are immunodominant over responses to other CSP domains despite the presence of similar numbers of naive B cells able to bind these regions. We find that this immunodominance is driven by avid binding of the CSP to cognate B cells that are able to expand at the expense of B cells with other specificities. We further show that mice immunized with repeat-truncated CSP molecules develop responses to subdominant epitopes and are protected against malaria. These data demonstrate that the CSP functions as a decoy, but truncated CSP molecules may be an approach for malaria vaccination.We thank Rajagopal Murugan and Hedda Wardemann (Deutsches Krebsforschungszentrum, Heidelberg, Germany) for providing the C-terminal antibodies
1710 and 3919 and Azza Idris, Joe Francica, and Robert Seder (Vaccine
Research Center, National Institutes of Health, Bethesda, MD) for the provision
of mAb15 and CSPCterm and CSPNterm peptides. We thank Michael Devoy, Harpreet Vohra, and Catherine Gillespie of the Imaging and Cytometry Facility at the
John Curtin School of Medical Research for assistance with flow cytometry and
multi-photon microscopy. We also thank Theresa Neeman of the ANU statistical
consulting unit for assistance with statistical analysis of the data. This work was
funded by the Bill and Melinda Gates Foundation (OPP1151018) and the National Health and Medical Research Council (GNT1158404). D.C. is supported
by Deutsche Forschungsgemeinschaft International Research Training Group
2290 and is the recipient of PhD scholarship from the Australian National
Universit
Cassini/Huygens Probe Entry, Descent, and Landing (EDL) at Titan Independent Technical Assessment
Starting in January 2004, the NESC has received several communications from knowledgeable technical experts at NASA expressing shared concerns (mainly at the Langley Research Center (LaRC) and Ames Research Center (ARC)) about Huygens mission success. It was suggested that NASA become more technically involved directly in the analysis of Huygens' entry, descent and landing (EDL) focusing on the parachute deployment trigger performance and the resultant effects on the operation of the parachute system, and the determination of the radiative heating environment at Titan by ESA and the corresponding thermal protection system (TPS) response. A NESC Team was formed and tasked to provide an independent assessment of these concerns. The results of that assessment are documented in this report
The GATA3 X308_Splice breast cancer mutation is a hormone context-dependent oncogenic driver
As the catalog of oncogenic driver mutations is expanding, it becomes clear that alterations in a given gene might have different functions and should not be lumped into one class. The transcription factor GATA3 is a paradigm of this. We investigated the functions of the most common GATA3 mutation (X308_Splice) and five additional mutations, which converge into a neoprotein that we called “neoGATA3,” associated with excellent prognosis in patients. Analysis of available molecular data from >3000 breast cancer patients revealed a dysregulation of the ER-dependent transcriptional response in tumors carrying neoGATA3-generating mutations. Mechanistic studies in vitro showed that neoGATA3 interferes with the transcriptional programs controlled by estrogen and progesterone receptors, without fully abrogating them. ChIP-Seq analysis indicated that ER binding is reduced in neoGATA3-expressing cells, especially at distal regions, suggesting that neoGATA3 interferes with the fine tuning of ER-dependent gene expression. This has opposite outputs in distinct hormonal context, having pro- or anti-proliferative effects, depending on the estrogen/progesterone ratio. Our data call for functional analyses of putative cancer drivers to guide clinical application.Institute of Cancer Research of the Medical University Vienna and by the grant P27361-B23 from the Austrian Science Grant (FWF), FXR was supported by SAF2011-29530 and SAF2015-70553-R grants from Ministerio de Economía y Competitividad (Madrid, Spain) (co-funded by the ERDF-EU), Fundación Científica de la Asociación Española Contra el Cáncer. CNIO is supported by Ministerio de Ciencia, Innovación y Universidades as a Centro de Excelencia Severo Ochoa SEV-2015-051
The Application of Novel Research Technologies by the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND) Consortium
The deep waters of the open ocean represent a major frontier in exploration and scientific understanding. However, modern technological and computational tools are making the deep ocean more accessible than ever before by facilitating increasingly sophisticated studies of deep ocean ecosystems. Here, we describe some of the cutting-edge technologies that have been employed by the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND; www.deependconsortium.org) Consortium to study the biodiverse fauna and dynamic physical-chemical environment of the offshore Gulf of Mexico (GoM) from 0 to 1,500 m
A multi-decade record of high quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)
The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) “living data” publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual data set files, included in the synthesis product, can be downloaded here: doi:10.1594/PANGAEA.849770. The gridded products are available here: doi:10.3334/CDIAC/OTG.SOCAT_V3_GRID
Energy-Efficient Control Adaptation with Safety Guarantees for Learning-Enabled Cyber-Physical Systems
Neural networks have been increasingly applied for control in learning-enabled cyber-physical systems (LE-CPSs) and demonstrated great promises in improving system performance and efficiency, as well as reducing the need for complex physical models. However, the lack of safety guarantees for such neural network based controllers has significantly impeded their adoption in safety-critical CPSs. In this work, we propose a controller adaptation approach that automatically switches among multiple controllers, including neural network controllers, to guarantee system safety and improve energy efficiency. Our approach includes two key components based on formal methods and machine learning. First, we approximate each controller with a Bernstein-polynomial based hybrid system model under bounded disturbance, and compute a safe invariant set for each controller based on its corresponding hybrid system. Intuitively, the invariant set of a controller defines the state space where the system can always remain safe under its control. The union of the controllers' invariants sets then define a safe adaptation space that is larger than (or equal to) that of each controller. Second, we develop a deep reinforcement learning method to learn a controller switching strategy for reducing the control/actuation energy cost, while with the help of a safety guard rule, ensuring that the system stays within the safe space. Experiments on a linear adaptive cruise control system and a non-linear Van der Pol's oscillator demonstrate the effectiveness of our approach on energy saving and safety enhancement
T-dependent B cell responses to Plasmodium induce antibodies that form a high-avidity multivalent complex with the circumsporozoite protein
The repeat region of the Plasmodium falciparum circumsporozoite protein (CSP) is a major vaccine antigen because it can be targeted by parasite neutralizing antibodies; however, little is known about this interaction. We used isothermal titration calorimetry, X-ray crystallography and mutagenesis-validated modeling to analyze the binding of a murine neutralizing antibody to Plasmodium falciparum CSP. Strikingly, we found that the repeat region of CSP is bound by multiple antibodies. This repeating pattern allows multiple weak interactions of single FAB domains to accumulate and yield a complex with a dissociation constant in the low nM range. Because the CSP protein can potentially cross-link multiple B cell receptors (BCRs) we hypothesized that the B cell response might be T cell independent. However, while there was a modest response in mice deficient in T cell help, the bulk of the response was T cell dependent. By sequencing the BCRs of CSP-repeat specific B cells in inbred mice we found that these cells underwent somatic hypermutation and affinity maturation indicative of a T-dependent response. Last, we found that the BCR repertoire of responding B cells was limited suggesting that the structural simplicity of the repeat may limit the breadth of the immune responseThis work was supported by the Bill and
Melinda Gates foundation http://www.
gatesfoundation.org (OPP1151018)
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