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Gut bacteria responding to dietary change encode sialidases that exhibit preference for red meat-associated carbohydrates.
Dietary habits have been associated with alterations of the human gut resident microorganisms contributing to obesity, diabetes and cancer1. In Western diets, red meat is a frequently eaten food2, but long-term consumption has been associated with increased risk of disease3,4. Red meat is enriched in N-glycolylneuraminic acid (Neu5Gc) that cannot be synthesized by humans5. However, consumption can cause Neu5Gc incorporation into cell surface glycans6, especially in carcinomas4,7. As a consequence, an inflammatory response is triggered when Neu5Gc-containing glycans encounter circulating anti-Neu5Gc antibodies8,9. Although bacteria can use free sialic acids as a nutrient source10-12, it is currently unknown if gut microorganisms contribute to releasing Neu5Gc from food. We found that a Neu5Gc-rich diet induces changes in the gut microbiota, with Bacteroidales and Clostridiales responding the most. Genome assembling of mouse and human shotgun metagenomic sequencing identified bacterial sialidases with previously unobserved substrate preference for Neu5Gc-containing glycans. X-ray crystallography revealed key amino acids potentially contributing to substrate preference. Additionally, we verified that mouse and human sialidases were able to release Neu5Gc from red meat. The release of Neu5Gc from red meat using bacterial sialidases could reduce the risk of inflammatory diseases associated with red meat consumption, including colorectal cancer4 and atherosclerosis13
Intense Electromagnetic Outbursts from Collapsing Hypermassive Neutron Stars
We study the gravitational collapse of a magnetized neutron star using a
novel numerical approach able to capture both the dynamics of the star and the
behavior of the surrounding plasma. In this approach, a fully general
relativistic magnetohydrodynamics implementation models the collapse of the
star and provides appropriate boundary conditions to a force-free model which
describes the stellar exterior. We validate this strategy by comparing with
known results for the rotating monopole and aligned rotator solutions and then
apply it to study both rotating and non-rotating stellar collapse scenarios,
and contrast the behavior with what is obtained when employing the
electrovacuum approximation outside the star. The non-rotating electrovacuum
collapse is shown to agree qualitatively with a Newtonian model of the
electromagnetic field outside a collapsing star. We illustrate and discuss a
fundamental difference between the force-free and electrovacuum solutions,
involving the appearance of large zones of electric-dominated field in the
vacuum case. This provides a clear demonstration of how dissipative
singularities appear generically in the non-linear time-evolution of force-free
fluids. In both the rotating and non-rotating cases, our simulations indicate
that the collapse induces a strong electromagnetic transient. In the case of
sub-millisecond rotation, the magnetic field experiences strong winding and the
transient carries much more energy. This result has important implications for
models of gamma-ray bursts.Comment: 28 pages, 20 figures (quality lowered to reduce sizes). Improved
initial data and matching condition results in a lower, but still important,
energy emission. Added appendix with a discussion on effects of transition
laye
Mycoplasma genitalium prevalence in Welsh sexual health patients: low antimicrobial resistance markers and no association of symptoms to bacterial load
Objectives Mycoplasma genitalium (MG) is a common cause of sexually transmitted infection, however no prevalence data is available for Wales. MG was detected by qPCR (quantitative) as well as two separate SpeeDx commercial assays, and related to clinical symptoms, age, gender and sample type. Methods Cervical swabs, urethral swabs and/or urine were collected from 1000 patients at walk-in sexual health clinics at 3 Welsh health centres from October 2017–October 2018. Extracted DNA was investigated to determine concordance between an in-house quantitative PCR, SpeeDx ResistancePlus® MG and the SpeeDx MG + parC (beta 2) assays; mutations in parC were substantiated by Sanger sequencing. Results MG was detected in 17/600 female patients (2.7%) and 13/400 (3.5%) male patients, with a 100% concordance between in-house qPCR and both SpeeDx assays. Macrolide resistance was low (relative to other studies), but more common in males (4/13; 30.8%) than females (2/17; 11.8%) and the only fluoroquinolone resistant sample (3.4% overall) was also macrolide resistant and detected from an MSM. Vaginitis was clinically apparent in 12/17 MG-positive females (2 with additional cervicitis, 1 with additional pelvic inflammatory disease), while 7 MG-positive males were asymptomatic. MG bacterial load did not correlate to clinical symptoms and females (4559 ± 1646/ml) had significantly lower MG load than males (84,714 ± 41,813/ml; p = 0.0429). Conclusions MG prevalence and antibiotic resistance in Welsh sexual health clinics is low. MG bacterial load did not correlate to clinical presentation, men have higher MG load/ml in urine than women, genders have different age bias for MG prevalence and urine and swabs are equivalent for detecting MG
Gene Expression Changes Related to Endocrine Function and Decline in Reproduction in Fathead Minnow (Pimephales promelas) after Dietary Methylmercury Exposure
BACKGROUND: Methylmercury (MeHg) is a known neurotoxic agent, but the mechanisms by which MeHg may act on reproductive pathways are relatively unknown. Several studies have indicated potential changes in hormone levels as well as declines in vertebrates with increasing dietary MeHg exposure. OBJECTIVES: The purpose of this study was to identify alterations in gene expression associated with MeHg exposure, specifically those associated with previously observed changes in reproduction and reproductive biomarkers. Fathead minnows, Pimephales promelas, were fed one of three diets that were similar to documented concentrations of MeHg in the diets of wild invertivorous and piscivorous fish. We used a commercial macroarray in conjunction with quantitative polymerase chain reaction to examine gene expression in fish in relation to exposure to these environmentally relevant doses of MeHg. RESULTS: Expression of genes commonly associated with endocrine disruption was altered with Hg exposure. Specifically, we observed a marked up-regulation in vitellogenin mRNA in individual Hg-exposed males and a significant decline in vitellogenin gene expression in female fish with increasing Hg concentrations. Other genes identified by the macroarray experiment included those associated with egg fertilization and development, sugar metabolism, apoptosis, and electron transport. We also observed differences in expression patterns between male and female fish not related to genes specifically associated with reproduction, indicating a potential physiological difference in the reaction of males and females to MeHg. CONCLUSION: Gene expression data may provide insight into the mechanisms by which MeHg affects reproduction in fish and indicate how MeHg differs in its effect from other heavy metals and endocrine-disrupting compounds
Volume 35, AMT-1 Cruise Report and Preliminary Results
This report documents the scientific activities on board the Royal Research Ship (RRS) 'James Clark Ross' during the irst Atlantic Meridional Transect (AMT-1), 21 September to 24 October 1995. The ship sailed from Grimsby (England) for Montevideo (Uruguay) and then continued on to Stanley (Falkland Islands). The primary objective of the AMT program is to investigate basic biological processes in the open Atlantic Ocean over very broad spatial scales. For AMT-1, the meridional range covered was approximately 50 deg N to 50 deg S or nearly 8,000 nmi. The measurements to be taken during the AMT cruises are fundamental for the calibration, validation, and continuing understanding of remotely sensed observations of biological oceanography. They are also important for understanding plankton community structure over latitudinal scales and the role of the world ocean in global carbon cycles. During AMT-1 a variety of instruments were used to map the physical, chemical, and biological structure of the upper 200 m of the water column. Ocean color measurements were made using state-of-the-art sensors, whose calibration was traceable to the highest international standards. New advances in fluorometry were used to measure photosynthetic activity, which was then used to further interpret primary productivity. A unique set of samples and data were collected for the planktonic assemblages that vary throughout the range of the transect. These data will yield new interpretations on community composition and their role in carbon cycling. While the various provinces of the Atlantic Ocean were being crossed, the partial pressure of CO2 was related to biological productivity. This comparison revealed the areas of drawdown of atmospheric CO2 and how these areas relate to the surrounding biological productivity. These data, plus the measurements of light attenuation and phytoplankton optical properties, will be used as a primary input for basin-scale biological productivity models to help develop ecosystem dynamics models which will be important for improving the forecasting abilities of modelers. The AMT program is also attempting to meet the needs of international agencies in their implementation of Sensor Intercomparison and Merger for Biological and Interdisciplinary Ocean Studies (SIMBIOS), a program to develop a methodology and operational capability to combine data products from the various ocean color satellite missions
The Extended Blue Continuum and Line Emission around the Central Radio Galaxy in Abell 2597
We present results from detailed imaging of the centrally dominant radio
elliptical galaxy in the cooling flow cluster Abell 2597, using data obtained
with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space
Telescope (HST). This object is one of the archetypal "blue-lobed" cooling flow
radio elliptical galaxies, also displaying a luminous emission-line nebula, a
compact radio source, and a significant dust lane and evidence of molecular gas
in its center. We show that the radio source is surrounded by a complex network
of emission-line filaments, some of which display a close spatial association
with the outer boundary of the radio lobes. We present a detailed analysis of
the physical properties of ionized and neutral gas associated with the radio
lobes, and show that their properties are strongly suggestive of direct
interactions between the radio plasma and ambient gas. We resolve the blue
continuum emission into a series of knots and clumps, and present evidence that
these are most likely due to regions of recent star formation. We investigate
several possible triggering mechanisms for the star formation, including direct
interactions with the radio source, filaments condensing from the cooling flow,
or the result of an interaction with a gas-rich galaxy, which may also have
been responsible for fueling the active nucleus. We propose that the properties
of the source are plausibly explained in terms of accretion of gas by the cD
during an interaction with a gas-rich galaxy, which combined with the fact that
this object is located at the center of a dense, high-pressure ICM can account
for the high rates of star formation and the strong confinement of the radio
source.Comment: Astrophysical Journal, in press, 34 pages, includes 6 PostScript
figures. Latex format, uses aaspp4.sty and epsf.sty file
Episodic Star Formation Coupled to Reignition of Radio Activity in 3C 236
We present Hubble Space Telescope UV and optical imaging of the radio galaxy
3C 236, whose relic 4 Mpc radio jet lobes and inner 2 kpc CSS radio source are
evidence of multiple epochs of AGN activity. Our data confirm the presence of
four bright knots of FUV emission in an arc along the edge of the inner
circumnuclear dust disk in the galaxy's nucleus, as well as FUV emission
cospatial with the nucleus itself. We interpret these to be sites of recent or
ongoing star formation. We present photometry of these knots, as well as an
estimate for the internal extinction in the source using the Balmer decrement
from SDSS spectroscopy. We estimate the ages of the knots by comparing our
extinction-corrected photometry with stellar population synthesis models. We
find the four knots cospatial with the dusty disk to be young, of order 10^7 yr
old. The FUV emission in the nucleus is likely due to an episode of star
formation triggered ~10^9 yr ago. We argue that the young 10^7 yr old knots
stem from an episode of star formation that was roughly coeval with the event
resulting in reignition of radio activity, creating the CSS source. The 10^9 yr
old stars in the nucleus may be associated with the previous epoch of activity
that generated the 4 Mpc relic source, before it was cut off by exhaustion or
interruption. The ages of the knots, considered in context with the disturbed
morphology of the nuclear dust and the double-double morphology of the "old"
and "young" radio sources, present evidence for an episodic AGN/starburst
connection. We suggest that the AGN fuel supply was interrupted for ~10^7 yr
due to a minor merger event and has now been restored, and the resultant
non-steady flow of gas toward the nucleus is likely responsible for both the
new episode of infall-induced star formation and also the multiple epochs of
radio activity.Comment: 15 pages, 7 figures. Accepted for publication in ApJ
Microbiomes attached to fresh perennial ryegrass are temporally resilient and adapt to changing ecological niches
Abstract Background Gut microbiomes, such as the rumen, greatly influence host nutrition due to their feed energy-harvesting capacity. We investigated temporal ecological interactions facilitating energy harvesting at the fresh perennial ryegrass (PRG)-biofilm interface in the rumen using an in sacco approach and prokaryotic metatranscriptomic profiling. Results Network analysis identified two distinct sub-microbiomes primarily representing primary (≤ 4 h) and secondary (≥ 4 h) colonisation phases and the most transcriptionally active bacterial families (i.e Fibrobacteriaceae, Selemondaceae and Methanobacteriaceae) did not interact with either sub-microbiome, indicating non-cooperative behaviour. Conversely, Prevotellaceae had most transcriptional activity within the primary sub-microbiome (focussed on protein metabolism) and Lachnospiraceae within the secondary sub-microbiome (focussed on carbohydrate degradation). Putative keystone taxa, with low transcriptional activity, were identified within both sub-microbiomes, highlighting the important synergistic role of minor bacterial families; however, we hypothesise that they may be ‘cheating’ in order to capitalise on the energy-harvesting capacity of other microbes. In terms of chemical cues underlying transition from primary to secondary colonisation phases, we suggest that AI-2-based quorum sensing plays a role, based on LuxS gene expression data, coupled with changes in PRG chemistry. Conclusions In summary, we show that fresh PRG-attached prokaryotes are resilient and adapt quickly to changing niches. This study provides the first major insight into the complex temporal ecological interactions occurring at the plant-biofilm interface within the rumen. The study also provides valuable insights into potential plant breeding strategies for development of the utopian plant, allowing optimal sustainable production of ruminants. Video Abstrac
Correction to: Microbiomes attached to fresh perennial ryegrass are temporally resilient and adapt to changing ecological niches
Following the publication of the original article [1], it was noticed that the figure image of Fig. 6 should be for Fig. 3. The image for Fig. 3 should be for Fig. 5 and Fig. 6 was missing. The correct Fig. 6 have been provided below and the original article has been updated to correct Figs. 3, 5 and 6. (Figure presented.)
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