Feo-transport of ferrous iron into bacteria

Bacteria commonly utilise a unique type of transporter, called Feo, to specifically acquire the ferrous (Fe2+) form of iron from their environment. Enterobacterial Feo systems are composed of three proteins: FeoA, a small, soluble SH3-domain protein probably located in the cytosol; FeoB, a large protein with a cytosolic N-terminal G-protein domain and a C-terminal integral inner-membrane domain containing two 'Gate' motifs which likely functions as the Fe2+ permease; and FeoC, a small protein apparently functioning as an [Fe-S]-dependent transcriptional repressor. We provide a review of the current literature combined with a bioinformatic assessment of bacterial Feo systems showing how they exhibit common features, as well as differences in organisation and composition which probably reflect variations in mechanisms employed and function.

Diallyl disulphide, a beneficial component of garlic oil, causes a redistribution of cell-cycle growth phases, induces apoptosis and enhances butyrate-induced apoptosis in colorectal adenocarcinoma cells (HT-29)

Colon cancer is a leading and expanding cause of death worldwide. A major contributory factor to this disease is diet composition; some components are beneficial (e.g. dietary fibre) whilst others are detrimental (e.g. alcohol). Garlic oil is a prominent dietary constituent that prevents the development of colorectal cancer. This effect is believed to be mainly due to diallyl disulphide (DADS), which selectively induces redox stress in cancerous (rather than normal) cells which leads to apoptotic cell death. However, the detailed mechanism by which DADS causes apoptosis remains unclear. We show that DADS-treatment of colonic adenocarcinoma cells (HT-29) initiates a cascade of molecular events characteristic of apoptosis. These include a decrease in cellular proliferation, translocation of phosphatidylserine to the plasma-membrane outer-layer, activation of caspase-3, genomic-DNA fragmentation and G2/M phase cell-cycle arrest. Short-chain fatty acids (SCFAs), particularly butyrate (abundantly produced in the gut by bacterial fermentation of dietary polysaccharides), enhance colonic cell integrity but, in contrast, inhibit colonic-cancer cell growth. Combining DADS with butyrate augmented the effect of butyrate on HT-29 cells. These results suggest that the anti-cancerous properties of DADS afford greater benefit when supplied with other favourable dietary factors (SCFA/polysaccharides) that likewise reduce colonic tumour development.

RACORO extended-term, aircraft observations of boundary-layer clouds

A first-of-a-kind, extended-term cloud aircraft campaign was conducted to obtain an in-situ statistical characterization of continental boundary-layer clouds needed to investigate cloud processes and refine retrieval algorithms. Coordinated by the Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF), the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign operated over the ARM Southern Great Plains (SGP) site from 22 January to 30 June 2009, collecting 260 h of data during 59 research flights. A comprehensive payload aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft measured cloud microphysics, solar and thermal radiation, physical aerosol properties, and atmospheric state parameters. Proximity to the SGP's extensive complement of surface measurements provides ancillary data that supports modeling studies and facilitates evaluation of a variety of surface retrieval algorithms. The five-month duration enabled sampling a range of conditions associated with the seasonal transition from winter to summer. Although about two-thirds of the cloud flights occurred in May and June, boundary-layer cloud fields were sampled under a variety of environmental and aerosol conditions, with about 77% of the flights occurring in cumulus and stratocumulus. Preliminary analyses illustrate use of these data to analyze cloud-aerosol relationships, characterize the horizontal variability of cloud radiative impacts, and evaluate surface-based retrievals. We discuss how an extended-term campaign requires a simplified operating paradigm that is different from that used for typical, short-term, intensive aircraft field programs.

Performance as social practice

Starting point for these outputs is a large scale research project in collaboration with the Zurich University for the Arts and the Kunstmuseum Thun, looking at a redefinition of Social Sculpture (Joseph Beuys/ Bazon Brock, 1970) as a functional device re-deployed to expand the art discourse into a societal discourse. Although Beuys‘ version of a social sculpture involved notions of abstruse mysticism and reformulations of a national identity these were never-the less part of a social transformation that shifted and re-arranged power relations. Following Laclau and Mouffe in their contention that democray is a fundamentally antagonistic process and contesting Grant Kester’s understanding of a ethically based relational practice, this work is alignes itself with Hirschhorn’s claim to an aesthetic practice within communities, following the possibility to view a socially based practice from both ends of the ethics debate, whereby ethical aspects fuels the aethetic to “create situations that are beautiful because they are ethical and shocking because they are ethical, thus in turn aesthetic because they are ethical” (O’Donnell). This project sets out to engage in activities which interact with surrounding communities and evoce new imaginations of site, thereby understanding site as a catalysts for subjective emergences. Performance is tested as a site for social practice. Archival research into local audio/visual resources, such as the Swiss Radio Archive, the Swiss Military Film Archives and zoological film archives of the Basel Zoo, was instrumental to the navigation of this work, under theme of crisis, catastrophy, landscape, fallout, in order to create a visual language for an active performance site. Commissioned by the Kunstmuseum Thun in collaboration with the University for the Arts in Zurich as part of a year long exhibition programme, (other artists are Jeanne Van Heeswijk (NL) and San Keller (CH), ) this project brings together a series of different works in a new performace installation. The performance process includes a performance workshop with 30 school children from local Swiss schools and their teachers, which was conducted publicly in the museum spaces. It enabled the children to engage with an unexpected set of tribal and animalistic behaviours, looking at situations of flight and rescue, resulting in a large performance choreography orchestration without an apparent conductor, it includes a collaboration with renowned Swiss zoologist, Prof Klaus Zuberbühler(University of St Andrews) and the Colonal General Haldimann commander of the military base in Thun. The installation included 2 static video images, shot in an around spectacular local cave site (Beatus Caves) including 3 children. The project will culminate in an edited edition of the Oncurating Journal, (issue no, tbc, in 2012) including interviews and essays from project collaborators. (Army Commander General, Thun, Jörg Hess, performance script, Timothy Long, and others)

Sensitivity of an Earth system climate model to idealized radiative forcing

We diagnose forcing and climate feedbacks in benchmark sensitivity experiments with the new Met Office Hadley Centre Earth system climate model HadGEM2-ES. To identify the impact of newly-included biogeophysical and chemical processes, results are compared to a parallel set of experiments performed with these processes switched off, and different couplings with the biogeochemistry. In abrupt carbon dioxide quadrupling experiments we find that the inclusion of these processes does not alter the global climate sensitivity of the model. However, when the change in carbon dioxide is uncoupled from the vegetation, or when the model is forced with a non-carbon dioxide forcing – an increase in solar constant – new feedbacks emerge that make the climate system less sensitive to external perturbations. We identify a strong negative dust-vegetation feedback on climate change that is small in standard carbon dioxide sensitivity experiments due to the physiological/fertilization effects of carbon dioxide on plants in this model.

Role for protease activity in visceral pain in irritable bowel syndrome

Mediators involved in the generation of symptoms in patients with irritable bowel syndrome (IBS) are poorly understood. Here we show that colonic biopsy samples from IBS patients release increased levels of proteolytic activity (arginine cleavage) compared to asymptomatic controls. This was dependent on the activation of NF-kappaB. In addition, increased proteolytic activity was measured in vivo, in colonic washes from IBS compared with control patients. Trypsin and tryptase expression and release were increased in colonic biopsies from IBS patients compared with control subjects. Biopsies from IBS patients (but not controls) released mediators that sensitized murine sensory neurons in culture. Sensitization was prevented by a serine protease inhibitor and was absent in neurons lacking functional protease-activated receptor-2 (PAR2). Supernatants from colonic biopsies of IBS patients, but not controls, also caused somatic and visceral hyperalgesia and allodynia in mice, when administered into the colon. These pronociceptive effects were inhibited by serine protease inhibitors and a PAR2 antagonist and were absent in PAR2-deficient mice. Our study establishes that proteases are released in IBS and that they can directly stimulate sensory neurons and generate hypersensitivity symptoms through the activation of PAR2.

Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability

Systematic climate shifts have been linked to multidecadal variability in observed sea surface temperatures in the North Atlantic Ocean1. These links are extensive, influencing a range of climate processes such as hurricane activity2 and African Sahel3, 4, 5 and Amazonian5 droughts. The variability is distinct from historical global-mean temperature changes and is commonly attributed to natural ocean oscillations6, 7, 8, 9, 10. A number of studies have provided evidence that aerosols can influence long-term changes in sea surface temperatures11, 12, but climate models have so far failed to reproduce these interactions6, 9 and the role of aerosols in decadal variability remains unclear. Here we use a state-of-the-art Earth system climate model to show that aerosol emissions and periods of volcanic activity explain 76 per cent of the simulated multidecadal variance in detrended 1860–2005 North Atlantic sea surface temperatures. After 1950, simulated variability is within observational estimates; our estimates for 1910–1940 capture twice the warming of previous generation models but do not explain the entire observed trend. Other processes, such as ocean circulation, may also have contributed to variability in the early twentieth century. Mechanistically, we find that inclusion of aerosol–cloud microphysical effects, which were included in few previous multimodel ensembles, dominates the magnitude (80 per cent) and the spatial pattern of the total surface aerosol forcing in the North Atlantic. Our findings suggest that anthropogenic aerosol emissions influenced a range of societally important historical climate events such as peaks in hurricane activity and Sahel drought. Decadal-scale model predictions of regional Atlantic climate will probably be improved by incorporating aerosol–cloud microphysical interactions and estimates of future concentrations of aerosols, emissions of which are directly addressable by policy actions.