Low-dose hypersensitivity in Chinese hamster V79 cells targeted with counted protons using a charged-particle microbeam

The Gray Laboratory charged-particle microbeam has been used to assess the clonogenic ability of Chinese hamster V79 cells after irradiation of their nuclei with a precisely defined number of protons with energies of 1.0 and 3.2 MeV. The microbeam uses a 1-mum. silica capillary collimator to deliver protons to subcellular targets with high accuracy. The detection system is based on a miniature photomultiplier tube positioned above the cell dish, which detects the photons generated by the passage of the charged particles through an 18-mum-thick scintillator placed below the cells. With this system, a detection efficiency of greater than 99% is achieved. The cells are plated on specially designed dishes (3-mum-thick Mylar base), and the nuclei are identified by fluorescence microscopy. After an incubation period of 3 days, the cells are revisited individually to assess the formation of colonies from the surviving cells. For each energy investigated, the survival curve obtained for the microbeam shows a significant deviation below I Gy from a response extrapolated using the LQ model for the survival data above 1 Gy. The data are well fitted by a model that supports the hypothesis that radioresistance is induced by low-dose hypersensitivity. These studies demonstrate the potential of the microbeam for performing studies of the effects of single charged particles on cells in vitro. The hypersensitive responses observed are comparable with those reported by others using different radiations and techniques. (C) 2001 by Radiation Research Society.

Weak interactions, omnivory and emergent food-web properties

Empirical studies have shown that, in real ecosystems, species-interaction strengths are generally skewed in their distribution towards weak interactions. Some theoretical work also suggests that weak interactions, especially in omnivorous links, are important for the local stability of a community at equilibrium. However, the majority of theoretical studies use uniform distributions of interaction strengths to generate artificial communities for study. We investigate the effects of the underlying interaction-strength distribution upon the return time, permanence and feasibility of simple Lotka-Volterra equilibrium communities. We show that a skew towards weak interactions promotes local and global stability only when omnivory is present. It is found that skewed interaction strengths are an emergent property of stable omnivorous communities, and that this skew towards weak interactions creates a dynamic constraint maintaining omnivory. Omnivory is more likely to occur when omnivorous interactions are skewed towards weak interactions. However, a skew towards weak interactions increases the return time to equilibrium, delays the recovery of ecosystems and hence decreases the stability of a community. When no skew is imposed, the set of stable omnivorous communities shows an emergent distribution of skewed interaction strengths. Our results apply to both local and global concepts of stability and are robust to the definition of a feasible community. These results are discussed in the light of empirical data and other theoretical studies, in conjunction with their broader implications for community assembly.

Gender mainstreaming and the Common Agricultural Policy

While there are many case studies looking at gender mainstreaming in national contexts, this article offers a pan-European perspective to examine how a stated commitment to gender equality at this meta-level works in practice. The European Union’s (EU) stated commitment to gender mainstreaming the Common Agricultural Policy (CAP) is critically reviewed. The article reviews theoretical literature on gender mainstreaming, considers the position of women in agriculture across Europe, and examines efforts by the EU to gender mainstream the CAP. It argues that at best, gender mainstreaming focuses on the symptoms of gender inequality in agriculture rather than the causes. Because of this, gender mainstreaming cannot be transformative in this context. Little thought has been given to the practical difficulties of actually gender mainstreaming a policy such as the CAP. The EU’s priority for the CAP focuses on the mainstream business goal of a viable agricultural industry and does not pay any heed to gender inequalities in agriculture. In short, the stated commitment to gender mainstreaming is empty rhetoric

Bending It Like Beckham: How to Visually Fool the Goalkeeper

Background: As bending free-kicks becomes the norm in modern day soccer, implications for goalkeepers have largely been ignored. Although it has been reported that poor sensitivity to visual acceleration makes it harder for expert goalkeepers to perceptually judge where the curved free-kicks will cross the goal line, it is unknown how this affects the goalkeeper's actual movements.

Methodology/Principal Findings: Here, an in-depth analysis of goalkeepers' hand movements in immersive, interactive virtual reality shows that they do not fully account for spin-induced lateral ball acceleration. Hand movements were found to be biased in the direction of initial ball heading, and for curved free-kicks this resulted in biases in a direction opposite to those necessary to save the free-kick. These movement errors result in less time to cover a now greater distance to stop the ball entering the goal. These and other details of the interceptive behaviour are explained using a simple mathematical model which shows how the goalkeeper controls his movements online with respect to the ball's current heading direction. Furthermore our results and model suggest how visual landmarks, such as the goalposts in this instance, may constrain the extent of the movement biases.

Conclusions: While it has previously been shown that humans can internalize the effects of gravitational acceleration, these results show that it is much more difficult for goalkeepers to account for spin-induced visual acceleration, which varies from situation to situation. The limited sensitivity of the human visual system for detecting acceleration, suggests that curved free-kicks are an important goal-scoring opportunity in the game of soccer.

Risk assessment of potentially toxic elements in agricultural soils and maize tissues from selected districts in Tanzania

A field survey was conducted to investigate the contamination of potentially toxic elements (PTEs) arsenic (As), lead (Pb), chromium (Cr), and nickel (Ni) in Tanzanian agricultural soils and to evaluate their uptake and translocation in maize as proxy to the safety of maize used for human and animal consumption. Soils and maize tissues were sampled from 40 farms in Tanzania and analyzed using inductively coupled plasma-mass spectrometry in the United Kingdom. The results showed high levels of PTEs in both soils and maize tissues above the recommended limits. Nickel levels of up to 34.4 and 56.9mgkg(-1) respectively were found in some maize shoots and grains from several districts. Also, high Pb levels >0.2mgkg(-1) were found in some grains. The grains and shoots with high levels of Ni and Pb are unfit for human and animal consumption. Concentrations of individual elements in maize tissues and soils did not correlate and showed differences in uptake and translocation. However, Ni showed a more efficient transfer from soils to shoots than As, Pb and Cr. Transfer of Cr and Ni from shoots to grains was higher than other elements, implying that whatever amount is assimilated in maize shoots is efficiently mobilized and transferred to grains. Thus, the study recommended to the public to stop consuming and feeding their animals maize with high levels of PTEs for their safety.

Market Basket Survey Shows Elevated Levels of As in South Central U.S. Processed Rice Compared to California: Consequences for Human Dietary Exposure:consequences for human dietary exposure

We report the largest market basket survey of arsenic (As) in U.S. rice to date. Our findings show differences in transitional-metal levels between polished and unpolished rice and geographical variation in As and selenium (Se) between rice processed in California and the South Central U.S. The mean and median As grain levels for the South Central U.S. were 0.30 and 0.27 µg As g-1, respectively, for 107 samples. Levels for California were 41% lower than the South Central U.S., with a mean of 0.17 µg As g-1 and a median of 0.16 µg As g-1 for 27 samples. The mean and median Se grain levels for the South Central U.S. were 0.19 µg Se g-1. Californian rice levels were lower, averaging only 0.08 and 0.06 µg Se g-1 for mean and median values, respectively. The difference between the two regions was found to be significant for As and Se (General Linear Model (GLM):? As p < 0.001; Se p < 0.001). No statistically significant differences were observed in As or Se levels between polished and unpolished rice (GLM:? As p = 0.213; Se p = 0.113). No significant differences in grain levels of manganese (Mn), cobalt (Co), copper (Cu), or zinc (Zn) were observed between California and the South Central U.S. Modeling arsenic intake for the U.S. population based on this survey shows that for certain groups (namely Hispanics, Asians, sufferers of Celiac disease, and infants) dietary exposure to inorganic As from elevated levels in rice potentially exceeds the maximum intake of As from drinking water (based on consumption of 1 L of 0.01 mg L-1 In. As) and Californian state exposure limits. Further studies on the transformation of As in soil, grain As bioavailability in the human gastrointestinal tract, and grain elemental speciation trends are critical.

Downstream changes in the transport and storage of sediment-associated contaminants (P, Cr and PCBs) in agricultural and industrialized drainage basins

Samples of suspended, floodplain and channel bed sediment have been used to examine downstream changes in ediment-associated contaminant transport and storage in contrasting rivers in Yorkshire, UK. The concentrations of hosphorus, chromium and selected PCBs associated with sediment in the River Aire and its main tributary, the River Calder, which drain an urbanized and industrialized catchment, are considerably higher than those in the relatively unpolluted River Swale, which drains an agricultural catchment. Concentrations of sediment-associated contaminants in the Aire/Calder system increase downstream, reflecting the location of urban and industrial areas in the middle and lower reaches, and the location of point source inputs, such as sewage treatment works. The ontaminant concentrations associated with floodplain and channel bed sediment in the Rivers Aire and Calder are high, particularly in the lower reaches. This, combined with measurements of sediment storage on the floodplain and channel bed, indicate that significant storage of sediment-associated contaminants occurs in the Rivers Aire and Calder.

Can we meet targets for biofuels and renewable energy in transport given the constraints imposed by policy in agriculture and energy?

The deployment of biofuels is significantly affected by policy in energy and agriculture. In the energy arena, concerns regarding the sustainability of biofuel systems and their impact on food prices led to a set of sustainability criteria in EU Directive 2009/28/EC on Renewable Energy. In addition, the 10% biofuels target by 2020 was replaced with a 10% renewable energy in transport target. This allows the share of renewable electricity used by electric vehicles to contribute to the mix in achieving the 2020 target. Furthermore, only biofuel systems that effect a 60% reduction in greenhouse gas emissions by 2020 compared with the fuel they replace are allowed to contribute to meeting the target. In the agricultural arena, cross-compliance (which is part of EU Common Agricultural Policy) dictates the allowable ratio of grassland to total agricultural land, and has a significant impact on which biofuels may be supported. This paper outlines the impact of these policy areas and their implications for the production and use of biofuels in terms of the 2020 target for 10% renewable transport energy, focusing on Ireland. The policies effectively impose constraints on many conventional energy crop biofuels and reinforce the merits of using biomethane, a gaseous biofuel. The analysis shows that Ireland can potentially satisfy 15% of renewable energy in transport by 2020 (allowing for double credit for biofuels from residues and ligno-cellulosic materials, as per Directive 2009/28/EC) through the use of indigenous biofuels: grass biomethane, waste and residue derived biofuels, electric vehicles and rapeseed biodiesel. © 2010 Elsevier Ltd. All rights reserved.

Isolation and characterization of a novel simazine-degrading bacterium from agricultural soil of central Chile, Pseudomonas sp MHP41

s-Triazine herbicides are used extensively in South America in agriculture and forestry. In this study, a bacterium designated as strain MHP41, capable of degrading simazine and atrazine, was isolated from agricultural soil in the Quillota valley, central Chile. Strain MHP41 is able to grow in minimal medium, using simazine as the sole nitrogen source. In this medium, the bacterium exhibited a growth rate of mu = 0.10 h(-1), yielding a high biomass of 4.2 x 10(8) CFU mL(-1). Resting cells of strain MHP41 degrade more than 80% of simazine within 60 min. The atzA, atzB, atzC, atzD, atzE and atzF genes encoding the enzymes of the simazine upper and lower pathways were detected in strain MHP41. The motile Gram-negative bacterium was identified as a Pseudomonas sp., based on the Biolog microplate system and comparative sequence analyses of the 16S rRNA gene. Amplified ribosomal DNA restriction analysis allowed the differentiation of strain MHP41 from Pseudomonas sp. ADP. The comparative 16S rRNA gene sequence analyses suggested that strain MHP41 is closely related to Pseudomonas nitroreducens and Pseudomonas multiresinovorans. This is the first s-triazine-degrading bacterium isolated in South America. Strain MHP41 is a potential biocatalyst for the remediation of s-triazine-contaminated environments.

The outer membrane of Brucella ovis shows increased permeability to hydrophobic probes and is more susceptible to cationic peptides than are the outer membranes of mutant rough Brucella abortus strains

The permeability of the outer membrane (OM) to hydrophobic probes and its susceptibility to bactericidal cationic peptides were investigated for natural rough Brucella ovis and for mutant rough Brucella abortus strains. The OM of B. ovis displayed an abrupt and faster kinetic profile than rough B. abortus during the uptake of the hydrophobic probe N-phenyl-naphthylamine. B. ovis was more sensitive than rough B. abortus to the action of cationic peptides. Bactenecins 5 and 7 induced morphological alterations on the OMs of both rough Brucella strains. B. ovis lipopolysaccharide (LPS) captured considerably more polymyxin B than LPSs from both rough and smooth B. abortus strains. Polymyxin B, poly-L-lysine, and poly-L-ornithine produced a thick coating on the surfaces of both strains, which was more evident in B. ovis than in rough B. abortus. The distinct functional properties of the OMs of these two rough strains correlate with some structural differences of their OMs and with their different biological behaviors in animals and culture cells.

Food miles or carbon emissions? Exploring labeling preference for food transport footprint with a stated choice study

The ecological footprint of food transport can be communicated using carbon dioxide emissions (CO2 label) or by providing information about both the length of time and the mileage travelled (food miles label). We use stated choice data to estimate conventional unobserved taste heterogeneity models and extend them to a specification that also addresses attribute nonattendance. The implied posterior distributions of the marginal willingness to pay values are compared graphically and are used in validation regressions. We find strong bimodality of taste distribution as the emerging feature, with different groups of subjects having low and high valuations for these labels. The best fitting model shows that CO2 and food miles valuations are much correlated. CO2 valuations can be high even for those respondents expressing low valuations for food miles. However, the reverse is not true. Taken together, the results suggest that consumers tend to value the CO2 label at least as much and sometimes more than the food miles label.