Sequestration of quaternary ammonium compounds in soil and its relevance for the proliferation of antibiotic resistance in the environment

Quaternary ammonium compounds (QACs) are a group of surface-active, biocidal, high production volume chemicals. In the agricultural sector, their applications are especially broad and range from disinfectants and detergents in animal husbandry to their use as adjuvants in pesticide formulations. Inputs of QACs into agroecosystems are potentially high where manures, sewage sludge or wastewater are applied to the farmer’s fields for nutrient recycling. The presence of QACs in the environment has frequently been inflicted in the co-selection for antibiotic resistance genes (ARGs) with unforeseeable risks for environmental and human health [1]–[3]. The selection of ARGs depends on concentrations of QACs in bio-accessible form and the persistence of these compounds. However, a comprehensive overview on i) predicted & measured concentrations of QACs in soils including their analysis, ii) mechanisms of their sequestration in soils based on their physicochemical and structural properties, and iii) the implications of the concentrations and the fate of QACs in soils for the proliferation of ARGs in the environment is missing. Based on a review of these topics, we propose that QACs are sequestered in the interlayer regions of clay minerals in soils, which reduces their acute toxicity, but increases their persistence. The slow release of QACs from the interlayer regions may maintain concentrations levels in soil solution that are large enough to co-select for antibiotic resistant soil bacteria promoting the proliferation of ARGs in the environment

Using the class 1 integron-integrase gene as a proxy for anthropogenic pollution

This is the final version of the article. Available from the publisher via the DOI in this record.Around all human activity, there are zones of pollution with pesticides, heavy metals, pharmaceuticals, personal care products and the microorganisms associated with human waste streams and agriculture. This diversity of pollutants, whose concentration varies spatially and temporally, is a major challenge for monitoring. Here, we suggest that the relative abundance of the clinical class 1 integron-integrase gene, intI1, is a good proxy for pollution because: (1) intI1 is linked to genes conferring resistance to antibiotics, disinfectants and heavy metals; (2) it is found in a wide variety of pathogenic and nonpathogenic bacteria; (3) its abundance can change rapidly because its host cells can have rapid generation times and it can move between bacteria by horizontal gene transfer; and (4) a single DNA sequence variant of intI1 is now found on a wide diversity of xenogenetic elements, these being complex mosaic DNA elements fixed through the agency of human selection. Here we review the literature examining the relationship between anthropogenic impacts and the abundance of intI1, and outline an approach by which intI1 could serve as a proxy for anthropogenic pollution.MRG is supported by the Australian Research Council, AP is supported by the Alfred P Sloan Foundation Microbiology of the Built Environment program and the National Science Foundation RAPID award no. 1402651, KS is supported by the Deutsche Forschungsgemeinschaft (DFG) funding the Research Unit FOR 566 ‘Veterinary Medicines in Soil: Basic Research for Risk Analysis’ (Grant No. SM59/5-3) and by the Umweltbundesamt (3713 63 402), JMT is supported by the US National Science Foundation and Y-GZ is supported by the National Science Foundation of China

The impact of resource dependence of the mechanisms of life on the spatial population dynamics of an in silico microbial community

Biodiversity has a critical impact on ecosystem functionality and stability, and thus the current biodiversity crisis has motivated many studies of the mechanisms that sustain biodiversity, a notable example being non-transitive or cyclic competition. We therefore extend existing microscopic models of communities with cyclic competition by incorporating resource dependence in demographic processes, characteristics of natural systems often oversimplified or overlooked by modellers. The spatially explicit nature of our individual-based model of three interacting species results in the formation of stable spatial structures, which have significant effects on community functioning, in agreement with experimental observations of pattern formation in microbial communities. Published by AIP Publishing

J. Cell. Sci.

Electrophysiological studies demonstrate that transient receptor potential vanilloid subtype 1 (TRPV1) is involved in neuronal transmission. Although it is expressed in the peripheral as well as the central nervous system, the questions remain whether TRPV1 is present in synaptic structures and whether it is involved in synaptic processes. In the present study we gathered evidence that TRPV1 can be detected in spines of cortical neurons, that it colocalizes with both pre- and postsynaptic proteins, and that it regulates spine morphology. Moreover, TRPV1 is also present in biochemically prepared synaptosomes endogenously. In F11 cells, a cell line derived from dorsal-root-ganglion neurons, TRPV1 is enriched in the tips of elongated filopodia and also at sites of cell-cell contact. In addition, we also detected TRPV1 in synaptic transport vesicles, and in transport packets within filopodia and neurites. Using FM4-64 dye, we demonstrate that recycling and/or fusion of these vesicles can be rapidly modulated by TRPV1 activation, leading to rapid reorganization of filopodial structure. These data suggest that TRPV1 is involved in processes such as neuronal network formation, synapse modulation and release of synaptic transmitters

PCR-based detection of mobile genetic elements in total community DNA

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