2,246 research outputs found
Meeting update: faecal microbiota transplantation––bench, bedside, courtroom?
A group of stakeholders met, under the aegis of the British Society of Gastroenterology, to discuss the current landscape of faecal microbiota transplant- ation (FMT) within the UK and beyond. The meeting covered a wide range of topics, ranging from the practical aspects of establishing an FMT service and regu- latory issues relating to its delivery, to research implications and likely future directions
Petrology and geochemistry of mafic and ultramafic cumulate rocks from the eastern part of the Sabzevar ophiolite (NE Iran): Implications for their petrogenesis and tectonic setting
The Late Cretaceous Sabzevar ophiolite represents one of the largest and most complete fragments of Tethyan
oceanic lithosphere in the NE Iran. It is mainly composed of serpentinized mantle peridotites slices; nonetheless,
minor tectonic slices of all crustal sequence constituents are observed in this ophiolite. The crustal sequence
contains a well-developed ultramafic and mafic cumulates section, comprising plagioclase-bearing wehrlite,
olivine clinopyroxenite, olivine gabbronorite, gabbronorite, amphibole gabbronorite and quartz gabbronorite
with adcumulate, mesocumulate, heteradcumulate and orthocumulate textures. The crystallization order for these
rocks is olivine chromian spinel → clinopyroxene → plagioclase → orthopyroxene → amphibole. The presence
of primary magmatic amphiboles in the cumulate rocks shows that the parent magma evolved under hydrous
conditions. Geochemically, the studied rock units are characterized by low TiO2 (0.18–0.57 wt.%), P2O5 (<0.05
wt.%), K2O (0.01–0.51 wt.%) and total alkali contents (0.12–3.04 wt.%). They indicate fractionated trends in the
chondrite-normalized rare earth element (REE) plots and multi-element diagrams (spider diagrams). The general
trend of the spider diagrams exhibit slight enrichment in large ion lithophile elements (LILEs) relative to high field
strength elements (HFSEs) and positive anomalies in Sr, Pb and Eu and negative anomalies in Zr and Nb relative to
the adjacent elements. The REE plots of these rocks display increasing trend from La to Sm, positive Eu anomaly
(Eu/Eu* ¼ 1.06–1.54) and an almost flat pattern from medium REE (MREE) to heavy REE (HREE) region [(Gd/
Yb)N ¼ 1–1.17]. Moreover, clinopyroxenes from the cumulate rocks have low REE contents and show marked
depletion in light REE (LREE) compared to MREE and HREE [(La/Sm)N ¼ 0.10–0.27 and (La/Yb)N ¼ 0.08–0.22].
The composition of calculated melts in equilibrium with the clinopyroxenes from less evolved cumulate samples
are closely similar to island arc tholeiitic (IAT) magmas. Modal mineralogy, geochemical features and REE
modeling indicate that Sabzevar cumulate rocks were formed by crystal accumulation from a hydrous depleted
basaltic melt with IAT affinity. This melt has been produced by moderate to high degree (~15%) of partial
melting a depleted mantle source, which partially underwent metasomatic enrichment from subducted slab
components in an intra-oceanic arc setting
Social media and virality in the 2014 student protests in Venezuela: Rethinking engagement and dialogue in times of imitation
This article examines the relationship between social media, political mobilization, and civic engagement in the context of the 2014 student protests in Venezuela. The study investigates whether these technologies were used by participants as a catalyst to trigger the protests and amplify them across the country or whether they were a galvanizing factor among more general conditions. The analysis uses cultural chaos and virality/contagion as theoretical approaches to discuss these events to provoke discussion about the relationship between protests and social media. However, far from a techno-deterministic assumption that sees social media as somehow having agency in itself, the authors highlight the role of social media as a platform for political engagement through imitation and emotions while rejecting false dichotomies of rationality/irrationality among the crowd
Interactions between multiple helminths and the gut microbiota in wild rodents
The gut microbiota is vital to host health and, as such, it is important to elucidate the mechanisms altering its composition and diversity. Intestinal helminths are host immunomodulators and have evolved both temporally and spatially in close association with the gut microbiota, resulting in potential mechanistic interplay. Host-helminth and host-microbiota interactions are comparatively well-examined, unlike microbiota-helminth relationships, which typically focus on experimental infection with a single helminth species in laboratory animals. Here, in addition to a review of the literature on helminth-microbiota interactions, we examined empirically the association between microbiota diversity and composition and natural infection of multiple helminth species in wild mice (Apodemus flavicollis), using 16S rRNA gene catalogues (metataxonomics). In general, helminth presence is linked with high microbiota diversity, which may confer health benefits to the host. Within our wild rodent system variation in the composition and abundance of gut microbial taxa associated with helminths was specific to each helminth species and occurred both up- and downstream of a given helminth's niche (gut position). The most pronounced helminth-microbiota association was between the presence of tapeworms in the small intestine and increased S24-7 (Bacteroidetes) family in the stomach. Helminths clearly have the potential to alter gut homeostasis. Free-living rodents with a diverse helminth community offer a useful model system that enables both correlative (this study) and manipulative inference to elucidate helminth-microbiota interactions
Moving beyond DNA: towards functional analysis of the vaginal microbiome by non-sequencing-based methods
Over the last two decades, sequencing-based methods have revolutionised our understanding of niche-specific microbial complexity. In the lower female reproductive tract, these approaches have enabled identification of bacterial compositional structures associated with health and disease. Application of metagenomics and metatranscriptomics strategies have provided insight into the putative function of these communities but it is increasingly clear that direct measures of microbial and host cell function are required to understand the contribution of microbe–host interactions to pathophysiology. Here we explore and discuss current methods and approaches, many of which rely upon mass-spectrometry, being used to capture functional insight into the vaginal mucosal interface. In addition to improving mechanistic understanding, these methods offer innovative solutions for the development of diagnostic and therapeutic strategies designed to improve women’s health
The domestication of the probiotic bacterium Lactobacillus acidophilus
Lactobacillus acidophilus is a Gram-positive lactic acid bacterium that has had widespread historical use in the dairy industry and more recently as a probiotic. Although L. acidophilus has been designated as safe for human consumption, increasing commercial regulation and clinical demands for probiotic validation has resulted in a need to understand its genetic diversity. By drawing on large, well-characterised collections of lactic acid bacteria, we examined L. acidophilus isolates spanning 92 years and including multiple strains in current commercial use. Analysis of the whole genome sequence data set (34 isolate genomes) demonstrated L. acidophilus was a low diversity, monophyletic species with commercial isolates essentially identical at the sequence level. Our results indicate that commercial use has domesticated L. acidophilus with genetically stable, invariant strains being consumed globally by the human population
Gamma-ray emission revealed at the western edge of SNR G344.7-0.1
We report on the investigation of a very high energy (VHE), Galactic
gamma-ray source recently discovered at >50GeV using the Large Area Telescope
(LAT) on board the Fermi Gamma-Ray Space Telescope. This object, 2FHL
J1703.4-4145, displays a very hard >50GeV spectrum with a photon index ~1.2 in
the 2FHL catalog and, as such, is one of the most extreme sources in the 2FHL
sub-sample of Galactic objects. A detailed analysis of the available
multi-wavelength data shows that this source is located on the western edge of
the supernova remnant (SNR) G344.7--0.1, along with extended TeV source, HESS
J1702-420. The observations and the spectral energy distribution modeling
support a scenario where this gamma-ray source is the byproduct of the
interaction between the SNR shock and the dense surrounding medium, with
escaping cosmic rays (CRs) diffusing into the dense environment and interacting
with a large local cloud, generating the observed TeV emission. If confirmed,
an interaction between the SNR CRs and a nearby cloud would make 2FHL
J1703.4-4145 another promising candidate for efficient particle acceleration of
the 2FHL Galactic sample, following the first candidate from our previous
investigation of a likely shock-cloud interaction occurring on the West edge of
the Vela SNR.Comment: 9 pages, 7 figures, Submitted to ApJ June 15, 2020. Accepted for
publication Oct 2, 202
Haloalkane-utilizing Rhodococcus strains isolated from geographically distinct locations possess a highly conserved gene cluster encoding haloalkane catabolism
The sequences of the 16S rRNA and haloalkane dehalogenase (dhaA) genes of five gram-positive haloalkane-utilizing bacteria isolated from contaminated sites in Europe, Japan, and the United States and of the archetypal haloalkane-degrading bacterium Rhodococcus sp. strain NCIMB13064 were compared. The 16S rRNA gene sequences showed less than 1% sequence divergence, and all haloalkane degraders clearly belonged to the genus Rhodococcus. All strains shared a completely conserved dhaA gene, suggesting that the dhaA genes were recently derived from a common ancestor. The genetic organization of the dhaA gene region in each of the haloalkane degraders was examined by hybridization analysis and DNA sequencing. Three different groups could be defined on the basis of the extent of the conserved dhaA segment. The minimal structure present in all strains consisted of a conserved region of 12.5 kb, which included the haloalkane-degradative gene cluster that was previously found in strain NCIMB13064. Plasmids of different sizes were found in all strains. Southern hybridization analysis with a dhaA gene probe suggested that all haloalkane degraders carry the dhaA gene region both on the chromosome and on a plasmid (70 to 100 kb). This suggests that an ancestral plasmid was transferred between these Rhodococcus strains and subsequently has undergone insertions or deletions. In addition, transposition events and/or plasmid integration may be responsible for positioning the dhaA gene region on the chromosome. The data suggest that the haloalkane dehalogenase gene regions of these gram-positive haloalkane-utilizing bacteria are composed of a single catabolic gene cluster that was recently distributed world-wide
Star-forming galaxies versus low- and high-excitation radio AGN in the VLA-COSMOS 3GHz Large Project
We study the composition of the faint radio population selected from the
VLA-COSMOS 3GHz Large Project, a radio continuum survey performed at 10 cm
wavelength. The survey covers the full 2 square degree COSMOS field with mean
Jy/beam, cataloging 10,899 source components above . By combining these radio data with UltraVISTA, optical, near-infrared,
and Spitzer/IRAC mid-infrared data, as well as X-ray data from the Chandra
Legacy, and Chandra COSMOS surveys, we gain insight into the emission
mechanisms within our radio sources out to redshifts of . From these
emission characteristics we classify our souces as star forming galaxies or
AGN. Using their multi-wavelength properties we further separate the AGN into
sub-samples dominated by radiatively efficient and inefficient AGN, often
referred to as high- and low-excitation emission line AGN. We compare our
method with other results based on fitting of the sources' spectral energy
distributions using both galaxy and AGN spectral models, and those based on the
infrared-radio correlation. We study the fractional contributions of these
sub-populations down to radio flux levels of 10 Jy. We find that at
3 GHz flux densities above 400 Jy quiescent, red galaxies,
consistent with the low-excitation radio AGN class constitute the dominant
fraction. Below densities of 200 Jy star-forming galaxies begin to
constitute the largest fraction, followed by the low-excitation, and X-ray- and
IR-identified high-excitation radio AGN.Comment: 7 pages, 3 figures, The many facets of extragalactic radio surveys:
towards new scientific challenges, Bologna 20-23 October 201
- …