3,433 research outputs found
Ruling out GeV thermal relic annihilating dark matter by radio observation of the Andromeda galaxy
In the past few years, some studies claimed that annihilating dark matter
with mass GeV can explain the GeV gamma-ray excess in our Galaxy.
However, recent analyses of the Fermi-LAT and radio observational data rule out
the possibility of the thermal relic annihilating dark matter with mass GeV for some popular annihilation channels. By using the new observed
radio data of the Andromeda galaxy, we rule out the existence of
GeV thermal relic annihilating dark matter for ten annihilation channels. The
lower limits of annihilating dark matter mass are improved to larger than 330
GeV for the most conservative case, which is a few times larger than the
current best constraints. Moreover, these limits strongly disfavor the
benchmark model of weakly interacting massive particle (WIMP) produced through
the thermal freeze-out mechanism.Comment: Accepted in Ap
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Regulation of axon repulsion by MAX-1 SUMOylation and AP-3.
During neural development, growing axons express specific surface receptors in response to various environmental guidance cues. These axon guidance receptors are regulated through intracellular trafficking and degradation to enable navigating axons to reach their targets. In Caenorhabditis elegans, the UNC-5 receptor is necessary for dorsal migration of developing motor axons. We previously found that MAX-1 is required for UNC-5-mediated axon repulsion, but its mechanism of action remained unclear. Here, we demonstrate that UNC-5-mediated axon repulsion in C. elegans motor axons requires both max-1 SUMOylation and the AP-3 complex β subunit gene, apb-3 Genetic interaction studies show that max-1 is SUMOylated by gei-17/PIAS1 and acts upstream of apb-3 Biochemical analysis suggests that constitutive interaction of MAX-1 and UNC-5 receptor is weakened by MAX-1 SUMOylation and by the presence of APB-3, a competitive interactor with UNC-5. Overexpression of APB-3 reroutes the trafficking of UNC-5 receptor into the lysosome for protein degradation. In vivo fluorescence recovery after photobleaching experiments shows that MAX-1 SUMOylation and APB-3 are required for proper trafficking of UNC-5 receptor in the axon. Our results demonstrate that SUMOylation of MAX-1 plays an important role in regulating AP-3-mediated trafficking and degradation of UNC-5 receptors during axon guidance
Stepwise Increases in Left Ventricular Mass Index and Decreases in Left Ventricular Ejection Fraction Correspond with the Stages of Chronic Kidney Disease in Diabetes Patients
Aims. Patients with diabetic nephropathy are reported to have a high prevalence of left
ventricular structural and functional abnormalities. This study was designed to assess
the determinants of left ventricular mass index (LVMI) and left ventricular ejection
fraction (LVEF) in diabetic patients at various stages of chronic kidney disease
(CKD).
Methods. This cross-sectional study enrolled 285 diabetic patients with CKD stages 3
to 5 from our outpatient department of internal medicine. Clinical and
echocardiographic parameters were compared and analyzed.
Results. We found a significant stepwise increase in LVMI (P < 0.001), LVH (P < 0.001), and LVEF <55% (P = 0.013) and a stepwise decrease in LVEF (P = 0.038)
corresponding to advance in CKD stages.
Conclusions. Our findings suggest that increases in LVMI and decreases in LVEF coincide
with advances in CKD stages in patients with diabetes
A Genome-Wide Analysis of Small Regulatory RNAs in the Human Pathogen Group A Streptococcus
The coordinated regulation of gene expression is essential for pathogens to infect and cause disease. A recently appreciated mechanism of regulation is that afforded by small regulatory RNA (sRNA) molecules. Here, we set out to assess the prevalence of sRNAs in the human bacterial pathogen group A Streptococcus (GAS). Genome-wide identification of candidate GAS sRNAs was performed through a tiling Affymetrix microarray approach and identified 40 candidate sRNAs within the M1T1 GAS strain MGAS2221. Together with a previous bioinformatic approach this brings the number of novel candidate sRNAs in GAS to 75, a number that approximates the number of GAS transcription factors. Transcripts were confirmed by Northern blot analysis for 16 of 32 candidate sRNAs tested, and the abundance of several of these sRNAs were shown to be temporally regulated. Six sRNAs were selected for further study and the promoter, transcriptional start site, and Rho-independent terminator identified for each. Significant variation was observed between the six sRNAs with respect to their stability during growth, and with respect to their inter- and/or intra-serotype-specific levels of abundance. To start to assess the contribution of sRNAs to gene regulation in M1T1 GAS we deleted the previously described sRNA PEL from four clinical isolates. Data from genome-wide expression microarray, quantitative RT-PCR, and Western blot analyses are consistent with PEL having no regulatory function in M1T1 GAS. The finding that candidate sRNA molecules are prevalent throughout the GAS genome provides significant impetus to the study of this fundamental gene-regulatory mechanism in an important human pathogen
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OMMA enables population-scale analysis of complex genomic features and phylogenomic relationships from nanochannel-based optical maps.
BackgroundOptical mapping is an emerging technology that complements sequencing-based methods in genome analysis. It is widely used in improving genome assemblies and detecting structural variations by providing information over much longer (up to 1 Mb) reads. Current standards in optical mapping analysis involve assembling optical maps into contigs and aligning them to a reference, which is limited to pairwise comparison and becomes bias-prone when analyzing multiple samples.FindingsWe present a new method, OMMA, that extends optical mapping to the study of complex genomic features by simultaneously interrogating optical maps across many samples in a reference-independent manner. OMMA captures and characterizes complex genomic features, e.g., multiple haplotypes, copy number variations, and subtelomeric structures when applied to 154 human samples across the 26 populations sequenced in the 1000 Genomes Project. For small genomes such as pathogenic bacteria, OMMA accurately reconstructs the phylogenomic relationships and identifies functional elements across 21 Acinetobacter baumannii strains.ConclusionsWith the increasing data throughput of optical mapping system, the use of this technology in comparative genome analysis across many samples will become feasible. OMMA is a timely solution that can address such computational need. The OMMA software is available at https://github.com/TF-Chan-Lab/OMTools
Discovery of serum biomarkers of alcoholic fatty liver in a rodent model: C-reactive protein
<p>Abstract</p> <p>Background</p> <p>Excessive consumption of alcohol contributes to alcoholic liver disease. Fatty liver is the early stage of alcohol-related liver disease. The aim of this study was to search for specific serological biomarkers of alcoholic fatty liver (AFL) compared to healthy controls, non-alcoholic fatty liver (NAFL) and liver fibrosis in a rodent model.</p> <p>Methods</p> <p>Serum samples derived from animals with AFL, NAFL, or liver fibrosis were characterized and compared using two-dimensional differential gel electrophoresis. A matrix-assisted laser desorption ionization-time of flight tandem mass spectrometer in conjunction with mascot software was used for protein identification. Subsequently, Western blotting and flexible multi-analyte profiling were used to measure the expressions of the putative biomarkers present in the serum of animals and clinical patients.</p> <p>Results</p> <p>Eight differential putative biomarkers were identified, and the two most differentiated proteins, including upregulated C-reactive protein (CRP) and downregulated haptoglobin (Hp), were further investigated. Western blotting validated that CRP was dramatically higher in the serum of AFL compared to healthy controls and other animals with liver disease of NAFL or liver fibrosis (<it>p </it>< 0.05). Moreover, we found that CRP and Hp were both lower in liver fibrosis of TAA-induced rats and clinical hepatitis C virus-infected patients.</p> <p>Conclusion</p> <p>The results suggest that increased levels of CRP are an early sign of AFL in rats. The abnormally elevated CRP induced by ethanol can be used as a biomarker to distinguish AFL from normal or otherwise diseased livers.</p
Untangling operational performance implication of ambidextrous blockchain initiatives: An empirical investigation of Chinese manufacturers
Purpose
Blockchain has been considered as a disruptive technology and every industry stands to benefit from it. According to Deloitte, increasing number of managers claim that their firms will suffer loss in competitive advantage if they do not adopt blockchain. Despite this motivation, insufficient knowledge on how can blockchain add value inhibits the commitment to its adoption. To better understand the possible influence of blockchain, two dimensions (exploitation and exploration) of blockchain initiatives are distinguished. This research aims to examine the impact of ambidextrous blockchain initiatives on firms' operational efficiency, as well as the moderating role of unabsorbed slack and environmental munificence.
Design/methodology/approach
In this paper, secondary panel data were collected from multiple sources to test the proposed hypotheses. Content analysis was adopted to operationalise ambidextrous blockchain initiatives from firms' official announcements.
Findings
The authors find that firms' ambidexterity in blockchain initiatives have significantly positive impact on operational efficiency. Furthermore, when firms have lower unabsorbed slack or in more munificent environments, they may benefit from managing a balance between exploration and exploitation.
Originality/value
This research offers some insightful theoretical and managerial implications of ambidextrous blockchain initiatives. The findings of this study contribute to blockchain literature by providing theory-driven empirical research
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