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Li C.,RWTH Aachen | Li C.,Shandong Agricultural University | Zhang B.,Chinese Academy of Agricultural Sciences | Ertunc T.,RWTH Aachen | And 4 more authors.
Environmental Science and Technology

The nature of the abiotic birnessite (δ-MnO2)-catalyzed transformation products of phenolic compounds in the presence of soil organic matter is crucial for understanding the fate and stability of ubiquitous phenolic carbon in the environment. 14C-radioactive and 13C-stable-isotope tracers were used to study the mineralization and transformation by δ-MnO2 of two typical humus and lignin phenolic monomers-catechol and p-coumaric acid-in the presence and absence of agricultural and forest soil humic acids (HAs) at pH 5-8. Mineralization decreased with increasing solution pH, and catechol was markedly more mineralized than p-coumaric acid. In the presence of HAs, the mineralization was strongly reduced, and considerable amounts of phenolic residues were bound to the HAs, independent of the solution pH. The HA-bound residues were homogeneously distributed within the humic molecules, and most still contained the unchanged aromatic ring as revealed by 13C NMR analysis, indicating that the residues were probably bound via ester or ether bonds. The study provides important information on δ-MnO2 stimulation of phenolic carbon binding to humic substances and the molecular distribution and chemical structure of the bound residues, which is essential for understanding the environmental fates of both naturally occurring and anthropogenic phenolic compounds. © 2012 American Chemical Society. Source

Jeong D.-H.,University of Delaware | Schmidt S.A.,University of Delaware | Rymarquis L.A.,University of Delaware | Rymarquis L.A.,Monsanto Corporation | And 15 more authors.
Genome Biology

Background: The wild grass Brachypodium distachyon has emerged as a model system for temperate grasses and biofuel plants. However, the global analysis of miRNAs, molecules known to be key for eukaryotic gene regulation, has been limited in B. distachyon to studies examining a few samples or that rely on computational predictions. Similarly an in-depth global analysis of miRNA-mediated target cleavage using parallel analysis of RNA ends (PARE) data is lacking in B. distachyon. Results: B. distachyon small RNAs were cloned and deeply sequenced from 17 libraries that represent different tissues and stresses. Using a computational pipeline, we identified 116 miRNAs including not only conserved miRNAs that have not been reported in B. distachyon, but also non-conserved miRNAs that were not found in other plants. To investigate miRNA-mediated cleavage function, four PARE libraries were constructed from key tissues and sequenced to a total depth of approximately 70 million sequences. The roughly 5 million distinct genome-matched sequences that resulted represent an extensive dataset for analyzing small RNA-guided cleavage events. Analysis of the PARE and miRNA data provided experimental evidence for miRNA-mediated cleavage of 264 sites in predicted miRNA targets. In addition, PARE analysis revealed that differentially expressed miRNAs in the same family guide specific target RNA cleavage in a correspondingly tissue-preferential manner. Conclusions: B. distachyon miRNAs and target RNAs were experimentally identified and analyzed. Knowledge gained from this study should provide insights into the roles of miRNAs and the regulation of their targets in B. distachyon and related plants. © 2013 Jeong et al. Source

Hoss S.,Ecossa | Hoss S.,Institute For Biodiversitat Netzwerk Ibn | Reiff N.,Ecossa | Nguyen H.T.,Dienstleistungszentrum Landlicher Raum Rheinpfalz | And 5 more authors.
Science of the Total Environment

Small-scale laboratory microcosms (30g soil in 50ml tubes) were evaluated for their suitability to assess the impact of chemicals on in situ soil nematode communities. For this purpose, appropriate conditions in the microcosms were explored to ensure stable conditions and a homogenous distribution of the nematodes. Then, the microcosms were used to assess the toxicity of insecticidal crystal proteins (Cry1A.105, Cry2Ab2, Cry3Bb1) present in genetically modified maize (MON89034×MON88017) on in situ nematode communities. Highly abundant and genus rich nematode communities could be maintained over a period of 12weeks. Due to a low variance between the replicates of the treatments, low detection limits could be achieved. Using meaningful stress indices, such as the maturity indices, the microcosm study revealed dose-dependent effects of the insecticidal Cry proteins that could be verified as toxic effects by comparing with effects of two positive controls (Cu, nematicidal Cry5B). Moreover, toxic effects could be differentiated from organic enrichment effects that were induced by the addition of plant material. With a NOECCommunity of 0.1mgkg-1 dry wt, the nematode communities reacted considerably more sensitive to the Cry proteins than a single-species nematode toxicity test (NOEC: 29mgl-1). The small-scale microcosm set-up turned out to be a suitable, low-budget tool for assessing the toxicity of chemicals on soil nematodes on community level, representing a link between single-species toxicity tests and large scale outdoor mesocosms. © 2013. Source

Rombke J.,ECT Oekotoxikologie GmbH | Barrett K.,Huntingdon Life science | Blanckenhorn W.U.,University of Zurich | Hargreaves T.,Charles River Associates | And 7 more authors.
Science of the Total Environment

A standardized bioassay using the face fly, Musca autumnalis L. (Diptera: Muscidae), was developed to test the lethal and sublethal toxicity of parasiticide residues in livestock dung. The repeatability of this test was assessed for the parasiticide ivermectin in seven tests performed in four laboratories in Germany and France. Additional results of limit tests were provided by two laboratories from the UK. Test results had an acceptable range of heterogeneity. The calculated effect concentration at which 50% emergence was observed (EC50) averaged 4.65 ± 2.17 (Standard Deviation (SD) μg ivermectin/kg fresh dung (range: 1.20-7.7)). Effects on emergence were, with one exception, not observed below the No Observed Effect Concentration (NOEC) ranging between 1.11 and 3.33μg ivermectin/kg. No effect on development time was observed. We conclude that the face fly is suitably sensitive, and the methods sufficiently repeatable, to support use of this standardized bioassay by the international community in the registration of new veterinary pharmaceuticals. Following these considerations, this species was accepted as a possible test organism in a recently published OECD Guideline (No. 228). © 2010 Elsevier B.V. Source

Mead-Briggs M.A.,Mambo Tox Ltd | Moll M.,Ibacon GmbH | Grimm C.,Syngenta | Schuld M.,GAB Biotechnologie GmbH | And 2 more authors.

This guideline describes a standardised form of extended laboratory test for evaluating the effects of plant protection products on the parasitic wasp, Aphidius rhopalosiphi (De Stefani-Perez) (Hymenoptera, Braconidae), both in terms of acute treatment effects (i.e. mortality over a 48 h exposure period) and sub-lethal treatment effects (i.e. changes in the reproductive capacity of surviving wasps). The test method involves the treatment of a 3-dimensional test substrate (barley seedlings), over which the test insects (laboratory-bred female wasps, less than 48-h-old) are confined for 48 h. Surviving wasps are then individually confined over untreated aphid-infested plants for 24 h and the numbers of parasitised aphids in which wasp pupae subsequently develop are recorded. Acute mortality after 48 h and the mean number of 'mummies' (the pupal stage of the wasps) produced per female are used as assessment endpoints for the test. © 2009 International Organization for Biological Control (IOBC). Source

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