Improved traceability of Shiga-toxin-producing <Emphasis Type="Italic">Escherichia coli</Emphasis> using CRISPRs for detection and typing

Among strains of Shiga-toxin-producing Escherichia coli (STEC), seven serogroups (O26, O45, O103, O111, O121, O145, and O157) are frequently associated with severe clinical illness in humans. The development of methods for their reliable detection from complex samples such as food has been challenging thus far, and is currently based on the PCR detection of the major virulence genes stx1, stx2, and eae, and O-serogroup-specific genes. However, this approach lacks resolution. Moreover, new STEC serotypes are continuously emerging worldwide. For example, in May 2011, strains belonging to the hitherto rarely detected STEC serotype O104:H4 were identified as causative agents of one of the world’s largest outbreak of disease with a high incidence of hemorrhagic colitis and hemolytic uremic syndrome in the infected patients. Discriminant typing of pathogens is crucial for epidemiological surveillance and investigations of outbreaks, and especially for tracking and tracing in case of accidental and deliberate contamination of food and water samples. Clustered regularly interspaced short palindromic repeats (CRISPRs) are composed of short, highly conserved DNA repeats separated by unique sequences of similar length. This distinctive sequence signature of CRISPRs can be used for strain typing in several bacterial species including STEC. This review discusses how CRISPRs have recently been used for STEC identification and typing.     

The food-print of Paris: long-term reconstruction of the nitrogen flows imported into the city from its rural hinterland

Between the tenth and twentieth century the population of Paris city increased from a few thousand to near 10 million inhabitants. In response to the growing urban demand during this period, the agrarian systems of the surrounding rural areas tremendously increased their potential for commercial export of agricultural products, made possible by a surplus of agricultural production over local consumption by humans and livestock in these areas. Expressed in terms of nitrogen, the potential for export increased from about 60 kg N/km2/year of rural territory in the Middle Ages, to more than 5,000 kg N/km2/year from modern agriculture. As a result of the balance between urban population growth and rural productivity, the rural area required to supply Paris (i.e. its food-print) did not change substantially for several centuries, remaining at the size of the Seine watershed surrounding the city (around 60,000 km2). The theoretical estimate of the size of the supplying hinterland at the end of the eighteenth century is confirmed by the figures deduced from the analysis of the historical city toll data (octroi). During the second half of the twentieth century, the ‘food-print’ of Paris reduced in size, owing to an unprecedented increase in the potential for commercial export associated with modern agricultural systems based on chemical N fertilization. We argue that analysing the capacity of territories to satisfy the demand for nitrogen-containing food products of local or distant urban population and markets might provide new and useful insights when assessing world food resource allocation in the context of increasing population and urbanization.     

Application of microbial hot spots enhances pesticide degradation in soils

Through transfer of an active, isoproturon degrading microbial community, pesticide mineralization could be successfully enhanced in various soils under laboratory and outdoor conditions. The microbes, extracted from a soil having high native ability to mineralize this chemical, were established on expanded clay particles and distributed to various soils in the form of microbial "hot spots". Both, diffusion controlled isoproturon mass flow towards these "hot spots" (6microg d(-1)) as well as microbial ability to mineralize the herbicide (approximately 5microg d(-1)) were identified as the main processes enabling a multiple augmentation of the native isoproturon mineralization even in soils with heavy metal contamination. Soil pH-value appears to exert an important effect on the sustainability of this process.     

Lysimeter Experiments to Investigate the Fate of Chemicals in Soils – Comparison of Five Different Lysimeter Systems

Several lysimeter scenarios and approaches exist to study the fate of agro-chemicals or contaminants from deposition in soil columns. In many systems just transport and leaching of the parent compound is followed, in some systems the leaching and transport of the metabolites is investigated as well. In more sophisticated lysimeter systems the volatilization and also the mineralization of the applied chemicals can be additionally monitored. Depending on the lysimeter system used and on the fact whether the applied chemicals are ¹⁴C-labeled or not, different results and various interpretations of the results might be achieved. Different lysimeter systems are described in this paper and a real dataset of a specific lysimeter experiment was transferred and evaluated in a virtual approach in the different lysimeter systems in order to show the advantages and disadvantages of the various systems.     

Sustainability, substance flow management and time. Part I Temporal analysis of substance flows

Flows of chemical substances need to be managed in a sustainable way. Sustainable development as a whole and the sustainable management of substance flows in particular are both time issues. These include the importance of the dynamics of substance flows and the way these interconnect with the use of resources, the avoidance of environmental pollution, and their effects on health and food production. Another prerequisite for the proper management of substance flows is justice within and between generations. This requires a systematic approach and a systematic analysis of the issues as well as of the actions to be taken. One tool for such a systematic approach is temporal analysis. It brings the temporal aspects of the substances themselves and of their intended use, as well as factors affecting the stakeholders, such as decision makers, producers and consumers, into focus. In the past, timing factors were rarely taken into account. Knowledge of the temporal dynamics of substance flows and their resultant outcomes, as well as of their interaction with ecological, economic and social systems, is a basic requirement for successful substance flow management. The need to include temporal aspects into substance flow management and how to do so is outlined here. Included are not only politicians but also practitioners and scientists who must explicitly take into account adequate time scales, points in time, breaks and other forms of time in planning and acting.     

Exposure to moderate concentrations of tropospheric ozone impairs tree stomatal response to carbon dioxide

With rising concentrations of both atmospheric carbon dioxide (CO₂) and tropospheric ozone (O₃), it is important to better understand the interacting effects of these two trace gases on plant physiology affecting land-atmosphere gas exchange. We investigated the effect of growth under elevated CO₂ and O₃, singly and in combination, on the primary short-term stomatal response to CO₂ concentration in paper birch at the Aspen FACE experiment. Leaves from trees grown in elevated CO₂ and/or O₃ exhibited weaker short-term responses of stomatal conductance to both an increase and a decrease in CO₂ concentration from current ambient level. The impairement of the stomatal CO₂ response by O₃ most likely developed progressively over the growing season as assessed by sap flux measurements. Our results suggest that expectations of plant water-savings and reduced stomatal air pollution uptake under rising atmospheric CO₂ may not hold for northern hardwood forests under concurrently rising tropospheric O₃.     

Beyond depletion: Daily self-control motivation as an explanation of self-control failure at work

The organizational self-control literature usually applies resource perspectives that explain self-control failure at work by depletion of self-control resources. However, these perspectives neglect the role of self-control motivation. On a daily level, we examine several self-control aspects (resources, motivation, demands, and effort) as predictors of a manifestation of self-control failure at work, namely, daily counterproductive work behavior toward the organization (CWB-O). Additionally, we investigate self-control effort as a mechanism predicting the depletion of self-control resources throughout the day. We analyzed data from 155 employees in a 2-week diary study with 2 daily measurement points. Multilevel path modeling showed that self-control motivation and self-control demands, but not self-control resource depletion, predicted self-control effort. There was an indirect effect from self-control motivation on CWB-O via self-control effort but no indirect effect from self-control demands on self-control resource depletion throughout the day via self-control effort. Findings suggest that self-control motivation is a crucial factor explaining self-control failure at work and cast further doubt on the idea that exerted self-control effort is the only mechanism leading to self-control resource depletion.     

Vapour pressures, aqueous solubility, Henry's law constants and air/water partition coefficients of 1,8-dichlorooctane and 1,8-dibromooctane

New data on the vapour pressures and aqueous solubility of 1,8-dichlorooctane and 1,8-dibromooctane are reported as a function of temperature between 20 °C and 80 °C and 1 °C and 40 °C, respectively. For the vapour pressures, a static method was used during the measurements which have an estimated uncertainty between 3% and 5%. The aqueous solubilities were determined using a dynamic saturation column method and the values are accurate to within ±10%. 1,8-Dichlorooctane is more volatile than 1,8-dibromooctane in the temperature range covered (p_sat varies from 3 to 250 Pa and from 0.53 to 62 Pa, respectively) and is also approximately three times more soluble in water (mole fraction solubilities at 25 °C of 5.95 × 10⁻⁷ and 1.92 × 10⁻⁷, respectively). A combination of the two sets of data allowed the calculation of the Henry’s law constants and the air water partition coefficients. A simple group contribution concept was used to rationalize the data obtained.     

Isolation and characterization of 1,2,4-trichlorobenzene mineralizing Bordetella sp. and its bioremediation potential in soil

A soil which has been polluted with chlorinated benzenes for more than 25 years was used for isolation of adapted microorganisms able to mineralize 1,2,4-trichlorobenzene (1,2,4-TCB). A microbial community was enriched from this soil and acclimated in liquid culture under aerobic conditions using 1,2,4-TCB as a sole available carbon source. From this community, two strains were isolated and identified by comparative sequence analysis of their 16S-rRNA coding genes as members of the genus Bordetella with Bordetella sp. QJ2-5 as the highest homological strain and with Bordetella petrii as the closest related described species. The 16S-rDNA of the two isolated strains showed a similarity of 100%. These strains were able to mineralize 1,2,4-TCB within two weeks to approximately 50% in liquid culture experiments. One of these strains was reinoculated to an agricultural soil with low native 1,2,4-TCB degradation capacity to investigate its bioremediation potential. The reinoculated strain kept its biodegradation capability: (14)C-labeled 1,2,4-TCB applied to this inoculated soil was mineralized to about 40% within one month of incubation. This indicates a possible application of the isolated Bordetella sp. for bioremediation of 1,2,4-TCB contaminated sites.     

Radium and radium-daughter nuclides in carbonates: a brief overview of strategies for determining chronologies

Radium isotopes have been used extensively to trace the movement of groundwater as well as oceanic water masses, but these radionuclides (and their daughters) are also useful chronometers for the determination of the time scales of other Earth and environmental processes. The purpose of this overview is to present the application of Ra and Ra daughters in the dating of carbonates. We show that the choice of dating method (decay of excess radionuclide or ingrowth of daughter) depends strongly on the parent/daughter activity ratios in the water in which the carbonate was precipitated. Thus freshly precipitated carbonates uniformly show excesses of ²²⁶Ra relative to its parent ²³⁰Th, and ²²⁶Ra decay can provide ages of carbonates over Holocene time scales. In contrast, carbonates are precipitated in waters of greatly varying ²¹⁰Pb/²²⁶Ra. Corals, deep-sea hydrothermal vent clams and the shelled cephalopod Nautilus live in waters with significant dissolved ²¹⁰Pb and all show excesses of ²¹⁰Pb in their carbonate. Bivalve molluscs from nearshore and coastal waters, and carbonates deposited from groundwater environments (e.g. travertines) in which ²¹⁰Pb is efficiently scavenged from solution, show deficiencies of ²¹⁰Pb relative to ²²⁶Ra. In contrast, fish otoliths strongly discriminate against ²¹⁰Pb regardless of the environment in which the fish lives. Deficiencies of ²²⁸Th relative to ²²⁸Ra are common in all carbonates. Useful time ranges for the ²¹⁰Pb/²²⁶Ra and ²²⁸Th/²²⁸Ra chronometers are ∼100 y and ∼10 y, respectively.