Increased hydrogen production by Escherichia coli strain HD701 in comparison with the wild-type parent strain MC4100

Hydrogen production by Escherichia coli is mediated by the formate hydrogenlyase (FHL) complex. E. coli strain HD701 cannot synthesize the FHL complex repressor, Hyc A. Consequently, it has an up-regulated FHL system and can, therefore, evolve hydrogen at a greater rate than its parental wild type, E. coli MC4100. Resting cells of E. coli strain HD701 and MC4100 were set up in batch mode in\ud phosphate buffered saline (PBS) to decouple growth from hydrogen production at the expense of sugar solutions of varying composition. Strain HD701 evolved several times more hydrogen than MC4100 at glucose concentrations ranging from 3 to 200 mM. The difference in the amount of H2 evolved by both strains decreased as the concentration of glucose increased. The highest rate of H2 evolution by strain HD701was 31ml h−1 ODunit −1 l−1 at a glucose concentration of 100 mM.With strain MC4100, the highest ratewas 16ml h−1 ODunit −1 l−1 under these conditions. Experiments using industrial wastes with a high sugar content yielded similar results. In each case, strain HD701\ud evolved hydrogen at a faster rate than the wild type, showing a possible potential for commercial hydrogen production

New observations on Saturnella saturnus (Steinecke) Fott: the first British record of a little-known enigmatic ‘green’ alga

Saturnella saturnus was discovered in March 2014 in open-water pools on blanket peatland at the Moor House - Upper Teesdale National Nature Reserve, straddling Cumbria and County Durham in NE England. This is the first record for the British Isles of a little-known alga known previously only from a few peat bog areas, mainly in mainland Europe. The literature is reviewed and new observations presented on its morphology and reproduction based on LM examination of living cells. New observations on the chloroplast structure and cytoplasmic inclusions (especially oil droplets) are discussed in relation to the findings of earlier studies. Doubt attaches as whether it is a chlorophyte or a xanthophyte and the identity of small spherical inclusions that have been frequently interpreted as autospores. It occurs in Upper Teesdale in pools that are that are small, relatively newly formed and mostly well-oxygenated. Also discussed is its relationship to Trochiscia, another coloniser of peatland pools. Photographic images are presented for the first time and comments made on its ecology in the context of blanket bog conservation projects and apparent rarity

The Neurobiological Impact of Ghrelin Suppression after Oesophagectomy

Ghrelin, discovered in 1999, is a 28-amino-acid hormone, best recognized as a stimulator of growth hormone secretion, but with pleiotropic functions in the area of energy homeostasis, such as appetite stimulation and energy expenditure regulation. As the intrinsic ligand of the growth hormone secretagogue receptor (GHS-R), ghrelin appears to have a broad array of effects, but its primary role is still an area of debate. Produced mainly from oxyntic glands in the stomach, but with a multitude of extra-metabolic roles, ghrelin is implicated in complex neurobiological processes. Comprehensive studies within the areas of obesity and metabolic surgery have clarified the mechanism of these operations. As a stimulator of growth hormone (GH), and an apparent inducer of positive energy balance, other areas of interest include its impact on carcinogenesis and tumour proliferation and its role in the cancer cachexia syndrome. This has led several authors to study the hormone in the cancer setting. Ghrelin levels are acutely reduced following an oesophagectomy, a primary treatment modality for oesophageal cancer. We sought to investigate the nature of this postoperative ghrelin suppression, and its neurobiological implications

Computing Creep-Damage Interactions in Irradiated Concrete

Among various degradation mechanisms possibly affecting the long-term operation of nuclear power plants, the effects of induced expansion and internal degradation occurring in concrete exposed to high-flux neutron radiation require additional research. Notably, using short-term test-reactor data to assess the long-term structural significance of light-water reactor concrete biological shields necessitates properly capturing the concurrent time-dependent effects, e.g., creep and damage caused by radiation-induced volumetric degradation. As this poses significant numerical challenges, a creep-damage algorithm was developed to account simultaneously for the progress of damage and viscoelastic processes in the concrete microstructure. The algorithm uses a time-adaptive scheme in which the instants at which damage occurs are explicitly searched for. This provides a nonlocal continuum damage procedure with very low sensitivity to the time or loading step. The proposed method is then used to simulate creep and restraint effects on radiation-induced degradation in concrete.This research is sponsored by the United State DOE Light Water Reactor Sustainability Program

Instantaneous Shape Sampling - a model for the γ\gamma-absorption cross section of transitional nuclei

The influence of the quadrupole shape fluctuations on the dipole vibrations in transitional nuclei is investigated in the framework of the Instantaneous Shape Sampling Model, which combines the Interacting Boson Model for the slow collective quadrupole motion with the Random Phase Approximation for the rapid dipole vibrations. Coupling to the complex background configurations is taken into account by folding the results with a Lorentzian with an energy dependent width. The low-energy energy portion of the $\gamma$- absorption cross section, which is important for photo-nuclear processes, is studied for the isotopic series of Kr, Xe, Ba, and Sm. The experimental cross sections are well reproduced. The low-energy cross section is determined by the Landau fragmentation of the dipole strength and its redistribution caused by the shape fluctuations. Collisional damping only wipes out fluctuations of the absorption cross section, generating the smooth energy dependence observed in experiment. In the case of semi-magic nuclei, shallow pygmy resonances are found in agreement with experiment

A BRiTE Journey: 2013–2019

Resilience is widely acknowledged as important for teacher success, yet how to assist pre-service teachers build the skills and strategies for professional resilience is a question often asked by teacher educators. This chapter overviews the design, development and features of a series of five online learning modules designed to support pre-service teacher resilience. The BRiTE modules were informed by an analysis of the literature and content created to address the key themes. Five modules were developed: Building resilience, Relationships, Wellbeing, Taking initiative and Emotions. Each module was designed to be interactive and personalised, enabling users to build their personal toolkit to support their resilience. Since their launch in 2015, the modules have been widely used by pre-service teachers, teachers and a range of stakeholders with over 14,000 registered users at the beginning of 2020. Potential for future use in supporting teacher resilience is discussed

The origin of large molecules in primordial autocatalytic reaction networks

Large molecules such as proteins and nucleic acids are crucial for life, yet their primordial origin remains a major puzzle. The production of large molecules, as we know it today, requires good catalysts, and the only good catalysts we know that can accomplish this task consist of large molecules. Thus the origin of large molecules is a chicken and egg problem in chemistry. Here we present a mechanism, based on autocatalytic sets (ACSs), that is a possible solution to this problem. We discuss a mathematical model describing the population dynamics of molecules in a stylized but prebiotically plausible chemistry. Large molecules can be produced in this chemistry by the coalescing of smaller ones, with the smallest molecules, the `food set', being buffered. Some of the reactions can be catalyzed by molecules within the chemistry with varying catalytic strengths. Normally the concentrations of large molecules in such a scenario are very small, diminishing exponentially with their size. ACSs, if present in the catalytic network, can focus the resources of the system into a sparse set of molecules. ACSs can produce a bistability in the population dynamics and, in particular, steady states wherein the ACS molecules dominate the population. However to reach these steady states from initial conditions that contain only the food set typically requires very large catalytic strengths, growing exponentially with the size of the catalyst molecule. We present a solution to this problem by studying `nested ACSs', a structure in which a small ACS is connected to a larger one and reinforces it. We show that when the network contains a cascade of nested ACSs with the catalytic strengths of molecules increasing gradually with their size (e.g., as a power law), a sparse subset of molecules including some very large molecules can come to dominate the system.Comment: 49 pages, 17 figures including supporting informatio

Characterization of MCF mammary epithelial cells overexpressing the Arylhydrocarbon receptor (AhR)

<p>Abstract</p> <p>Background</p> <p>Recent reports indicate the existence of breast cancer cells expressing very high levels of the Arylhydrocarbon receptor (AhR), a ubiquitous intracellular receptor best known for mediating toxic action of dioxin and related pollutants. Positive correlation between the degree of AhR overexpression and states of increasing transformation of mammary epithelial cells appears to occur in the absence of any exogenous AhR ligands. These observations have raised many questions such as why and how AhR is overexpressed in breast cancer and its physiological roles in the progression to advanced carcinogenic transformation. To address those questions, we hypothesized that AhR overexpression occurs in cells experiencing deficiencies in normally required estrogen receptor (ER) signaling, and the basic role of AhR in such cases is to guide the affected cells to develop orchestrated cellular changes aimed at substituting the normal functions of ER. At the same time, the AhR serves as the mediator of the cell survival program in the absence of ER signaling.</p> <p>Methods</p> <p>We subjected two lines of Michigan Cancer Foundation (MCF) mammary epithelial cells to 3 different types ER interacting agents for a number of passages and followed the changes in the expression of AhR mRNA. The resulting sublines were analyzed for phenotypical changes and unique molecular characteristics.</p> <p>Results</p> <p>MCF10AT1 cells continuously exposed to 17-beta-estradiol (E2) developed sub-lines that show AhR overexpression with the characteristic phenotype of increased proliferation, and distinct resistance to apoptosis. When these chemically selected cell lines were treated with a specific AhR antagonist, 3-methoxy-4-nitroflavone (MNF), both of the above abnormal cellular characteristics disappeared, indicating the pivotal role of AhR in expressing those cellular phenotypes. The most prominent molecular characteristics of these AhR overexpressing MCF cells were found to be overexpression of ErbB2 and COX-2. Furthermore, we could demonstrate that suppression of AhR functions through anti-AhR siRNA or MNF causes the recovery of ERalpha functions.</p> <p>Conclusion</p> <p>One of the main causes for AhR overexpression in these MCF breast cancer cells appears to be the loss of ERalpha functions. This phenomenon is likely to be based on the mutually antagonistic relationship between ER and AhR.</p

Combined acoustic radiation force impulse, aminotransferase to platelet ratio index and Forns index assessment for hepatic fibrosis grading in hepatitis B

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Building development and roads: implications for the distribution of stone curlews across the Brecks

Background: Substantial new housing and infrastructure development planned within England has the potential to conflict with the nature conservation interests of protected sites. The Breckland area of eastern England (the Brecks) is designated as a Special Protection Area for a number of bird species, including the stone curlew (for which it holds more than 60% of the UK total population). We explore the effect of buildings and roads on the spatial distribution of stone curlew nests across the Brecks in order to inform strategic development plans to avoid adverse effects on such European protected sites. Methodology: Using data across all years (and subsets of years) over the period 1988 – 2006 but restricted to habitat areas of arable land with suitable soils, we assessed nest density in relation to the distances to nearest settlements and to major roads. Measures of the local density of nearby buildings, roads and traffic levels were assessed using normal kernel distance-weighting functions. Quasi-Poisson generalised linear mixed models allowing for spatial auto-correlation were fitted. Results: Significantly lower densities of stone curlew nests were found at distances up to 1500m from settlements, and distances up to 1000m or more from major (trunk) roads. The best fitting models involved optimally distance-weighted variables for the extent of nearby buildings and the trunk road traffic levels. Significance : The results and predictions from this study of past data suggests there is cause for concern that future housing development and associated road infrastructure within the Breckland area could have negative impacts on the nesting stone curlew population. Given the strict legal protection afforded to the SPA the planning and conservation bodies have subsequently agreed precautionary restrictions on building development within the distances identified and used the modelling predictions to agree mitigation measures for proposed trunk road developments