Quorum sensing within the gut ecosystem

The successful modulation of phenotype is essential for the colonisation and proliferation of bacteria within the complex ecosystem of the gastrointestinal tract. To accomplish this, bacteria obtain and respond to information from the environment. One important parameter is the other bacteria present. The ability to correctly sense self, and also others, must therefore be advantageous for the control of mass action processes by the bacterial population. Within the gut ecosystem that may include processes involved in colonisation including those determining biofilm formation, pathogenicity, dispersal and DNA transfer. The ability to sense other bacteria may have important consequences for competitive and nutritional strategies controlling for example, entry into stationary phase, dispersal and the production of antimicrobial compounds. The ability to interfere with the signalling of bacteria will determine the fitness of the given organism to survive in the gut and may also have therapeutic potentia

Akkermansia muciniphila gen. nov., sp. nov., a human intestinal mucin-degrading bacterium

The diversity of mucin-degrading bacteria in the human intestine was investigated by combining culture and 16S rRNA-dependent approaches. A dominant bacterium, strain Muc(T), was isolated by dilution to extinction of faeces in anaerobic medium containing gastric mucin as the sole carbon and nitrogen source. A pure culture was obtained using the anaerobic soft agar technique. Strain Muc(T) was a Gram-negative, strictly anaerobic, non-motile, non-spore-forming, oval-shaped bacterium that could grow singly and in pairs. When grown on mucin medium, cells produced a capsule and were found to aggregate. Strain Muc(T) could grow on a limited number of sugars, including N-acetylglucosamine, N-acetylgalactosamine and glucose, but only when a protein source was provided and with a lower growth rate and final density than on mucin. The G+C content of DNA from strain Muc(T) was 47.6 mol%. 16S rRNA gene sequence analysis revealed that the isolate was part of the division Verrucomicrobia. The closest described relative of strain Muc(T) was Verrucomicrobium spinosum (92% sequence similarity). Remarkably, the 16S rRNA gene sequence of strain Muc(T) showed 99% similarity to three uncultured colonic bacteria. According to the data obtained in this work, strain Muc(T) represents a novel bacterium belonging to a new genus in subdivision 1 of the Verrucomicrobia; the name Akkermansia muciniphila gen. nov., so. nov. is proposed; the type strain is Muc(T) ( = ATCC BAA-835(T) = CIP 107961(T))

Development and application of a selective pcr-denaturing gradient gel electrophoresis approach to detect a recently cultivated Bacillus group predominant in soil

The worldwide presence of a hitherto-nondescribed group of predominant soil microorganisms related to Bacillus benzoevorans was analyzed after development of two sets of selective primers targeting 16S rRNA genes in combination with denaturing gradient gel electrophoresis (DGGE). The high abundance and cultivability of at least some of these microorganisms makes them an appropriate subject for studies on their biogeographical dissemination and diversity. Since cultivability can vary significantly with the physiological state and even between closely related strains, we developed a culture-independent 16S rRNA gene-targeted DGGE fingerprinting protocol for the detection of these bacteria from soil samples. The composition of the B. benzoevorans relatives in the soil samples from The Netherlands, Bulgaria, Russia, Pakistan, and Portugal showed remarkable differences between the different countries. Differences in the DGGE profiles of these communities in archived soil samples from the Dutch Wieringermeer polder were observed over time during which a shift from anaerobic to aerobic and from saline to freshwater conditions occurred. To complement the molecular methods, we additionally cultivated B. benzoevorans-related strains from all of the soil samples. The highest number of B. benzoevorans relatives was found in the soils from the northern part of The Netherlands. The present study contributes to our knowledge of the diversity and abundance of this interesting group of microbes in soils throughout the world

Autonomous Morphogenesis in Self-assembling Robots Using IR-Based Sensing and Local Communications

This paper presents a simple decentralised morphology control mechanism for a swarm of self-assembling robots. Each robot in the system is fully autonomous and controlled using a behaviour-based approach with only infrared-based local sensing and communications. A graph-based recruitment strategy is proposed to guide the growth of 2D planar organisms, and local communications are used to self-organise the behaviours of robots during the morphogenesis process. The effectiveness of the approach has been verified, in simulation, for a diverse set of target structures. © 2010 Springer-Verlag Berlin Heidelberg

The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

Komatiites as Mercury Surface Analogues: Spectral Measurements at PEL

X-ray fluorescence and gamma ray measurements by the NASA MESSENGER spacecraft orbiting Mercury show a surface composition strongly different from other terrestrial planets [1, 2]. The X-Ray Spectrometer (XRS) measures elemental composi-tion for the topmost 0.1 mm of Mercury’s regolith, while the Gamma Ray and Neutron Spectrometer (GRNS) is sensitive to depths of tens of centimeters. High Mg/Si and low Al/Si and Ca/Si ratios exclude a feldspathic surface composition like that of the lunar highlands. Mercury's surface mineralogy is likely dom-inated by magnesian orthopyroxene, sodium-rich pla-gioclase feldspar, and lesser amounts of Ca, Mg, and/or Fe sulfides. Enstatite chondrite melts and cer-tain enstatite achondrites provide a good compositional and mineralogical match for much of the surface of Mercury [3]. Elemental results from the GRNS [4] are consistent with those previously obtained by the X-Ray Spectrometer, including the high sulfur and low iron abundances. The elemental results from gamma-ray and X-ray spectrometry are most consistent with petro-logic models suggesting that Mercury's surface is dom-inated by magnesian silicates [5]. Mercury’s magne-sian silicates and high Mg/Si ratio (in excess of the Mg/Si ratio of terrestrial and lunar basalts [1]) invites comparison to the terrestrial ultramafic lavas known as komatiites. To assess komatiites as analogs for the surface of Mercury, at the Planetary Emissivity Laboratory (PEL) at the German Aerospace Center (DLR) we have measured visible and infrared spectra for a suite of komatiite samples under a range of environmental conditions

Spectral Reflectance Measurements of Sulfides at the Planetary Emissivity Laboratory — Analogs for Hollow-Forming Material on Mercury?

We present spectral reflectance measurements at visible and near-infrared wavelengths of fresh and heated samples of MnS, CaS, and MgS, as well as elemental sulfur. We infer that sulfides display a diagnostic feature at or near 0.6 µm