An agent model for business relationships

Relationships are fundamental to all but the most impersonal forms of interaction in business. An agent aims to secure projected needs by attempting to build a set of (business) relationships with other agents. A relationship is built by exchanging private information, and is characterised by its intimacy — degree of closeness — and balance — degree of fairness. Each argumentative interaction between two agents then has two goals: to satisfy some immediate need, and to do so in a way that develops the relationship in a desired direction. An agent’s desire to develop each relationship in a particular way then places constraints on the argumentative utterances. This paper describes argumentative interaction constrained by a desire to develop such relationships.Peer Reviewe

The 2015 Annual Meeting of SETAC German Language Branch in Zurich (7-10 September, 2015): ecotoxicology and environmental chemistry-from research to application

This report provides a brief review of the 20th annual meeting of the German Language Branch of the Society of Environmental Toxicology and Chemistry (SETAC GLB) held from September 7th to 10th 2015 at ETH (Swiss Technical University) in Zurich, Switzerland. The event was chaired by Inge Werner, Director of the Swiss Centre for Applied Ecotoxicology (Ecotox Centre) Eawag-EPFL, and organized by a team from Ecotox Centre, Eawag, Federal Office of the Environment, Federal Office of Agriculture, and Mesocosm GmbH (Germany). Over 200 delegates from academia, public agencies and private industry of Germany, Switzerland and Austria attended and discussed the current state of science and its application presented in 75 talks and 83 posters. In addition, three invited keynote speakers provided new insights into scientific knowledge ‘brokering’, and—as it was the International Year of Soil—the important role of healthy soil ecosystems. Awards were presented to young scientists for best oral and poster presentations, and for best 2014 master and doctoral theses. Program and abstracts of the meeting (mostly in German) are provided as Additional file 1

Development and application of sediment contact bioassays for the investigation of acute and mechanism specific toxicity with Danio rerio embryos

Sediments are a major issue for many scientists and authorities due to their close linkage to the aquatic food web and their potential to accumulate pollutants. Therefore, the European Water Framework Directive (EWFD) implements a daughter directive, which requires from the member states that the concentration of 33 priority pollutants should not increase above levels given by environmental quality standards defined in the regulation for sediments and biota. However, there is still need for basic research in order to fulfill this legal obligation. Exposure to native sediment samples provides an ecologically highly relevant and realistic exposure scenario, which takes bioavailability into account and simulates in situ exposure conditions. Therefore, the scope of the present study was the development and application of sediment contact bioassays with different biological endpoints. Since zebrafish larvae are being increasingly used in ecotoxicological investigations, it is crucial to understand their xenobiotic metabolism processes. The present PhD thesis has a strong focus on investigating the activity and the expression of the CYP1 family in early-life stages of zebrafish. Thus, the fish embryo EROD assay (FE-EROD) was developed to determine their basal and induced enzymatic activity with the measurement of 7-ethoxyresorufin-O-deethylase (EROD) activity. This newly developed FE-EROD assay is a combination of the in vitro cell line EROD assay and the sediment contact assay using zebrafish embryos. In addition, the induced and basal mRNA expression was investigated using quantitative real-time PCR (qPCR). The cyp1a, cyp1b1, and the cyp1c genes were investigated across embryonic development with different exposure times (48, 72, 96, 120 and 72-96 hpf). For the present study, three sediment samples were chosen. Embryos were exposed to different exposure scenarios (freeze-dried whole-sediment samples, extracts and four fractions) and tested in the Fish Embryo Toxicity (FET) test, the sediment contact assay (SCA) as well as in the newly developed FE-EROD and qPCR after in vivo exposure to whole embryos of the zebrafish. Additionally, the three sediment samples were fractionated due to their polarity to determine the active substances or substance classes which caused the observed effects. The sediment sample from the Vering canal showed the overall strongest toxic potential, followed by Altrip and Ehrenbreitstein. These results were underlined by the results of the chemical analysis: A high concentration of PAHs and heterocyclic compounds were found in the Vering canal extract. The samples from Altrip and Ehrenbreitstein showed a moderate contamination with PAHs and only minor concentrations of heterocyclic compounds. The prevalent teratogenic effects in all three sediments were a general retardation of the embryos, edemas of heart and yolk sac, absence of pigmentation, non-detachment of the tail and deformation of the spine. Additionally, the sediments samples from Altrip and the Vering canal showed a reduced hatching rate. These results were confirmed by the results of the fractions: same teratogenic effects were observed in the fraction 2 of the Vering canal. Furthermore, the teratogenic effects were found in the same fraction that also induced in the FE-EROD. The newly developed FE-EROD is suitable to investigate EROD activity in different exposure scenarios. It was shown that the EROD activity was first significantly induced in all sediment samples after 96 hpf in exposed embryos. All transcripts were induced by the potent AhR-agonist β-NF and the three tested freeze-dried sediments. Cyp1a showed the strongest induction, being up-regulated up to 380-fold. Moreover, it has been shown that the FE-EROD is suitable for being used in bioassay-directed fractionation processes. The results clearly showed EROD activity in the fraction 2 of all sediment samples. This fraction contains, among other classes, PAHs. In literature it is known that some of the PAHs are strong EROD inducers. Interestingly, the fraction 3 and 4 of the Vering canal showed also a high EROD activity. These fractions contain the more polar and polar substances classes like heterocyclic compounds. The analysis of the priority substances only often does not explain the observed results and sediments contain a complex mixture of contaminants. Therefore, synergistic and antagonistic effects must be taken into account. The present study clearly shows the relevance of sediments in order to achieve the goals of the EWFD. Beside established acute toxicity tests like the FET and SCA mechanism-specific bioassays will give more information about the toxic potential of sediments like the expression and activity of CYP1s. The in the FE-EROD included biomimetic exposure on whole sediments takes the bioavailability into account. The newly developed test system is comparable as it indicated toxicity in the same samples as the FET and the SCA

New insights into the toxicokinetics of 3,4-dichloroaniline in early life stages of zebrafish (Danio rerio)

In the fish embryo toxicity (FET) test with zebrafish (Danio rerio) embryos, 3,4-dichloroaniline (3,4-DCA) is often employed as a positive control substance. Previous studies have characterized bioconcentration and transformation of 3,4-DCA in this test under flow-through conditions. However, the dynamic changes of chemical concentrations in exposure media and embryos were not studied systematically under the commonly used semi-static exposure conditions in multiwell plates. To overcome these limitations, we conducted semi-static exposures experiments where embryolarval zebrafish were exposed to 0.5, 2.0, and 4.0 mg L−1 of 3,4-DCA for up to 120 hpf, with 24-h renewal intervals. During each renewal interval, concentrations of 3,4-DCA were quantified in water samples at 0, 6, 18, and 24 h using high-performance liquid chromatography with diode array detection. Levels of 3,4-DCA in larvae were measured after 120 h exposure. Concentrations of 3,4-DCA in the test vessels decreased rapidly during exposure. Taking these dynamics into account, bioconcentration factors in the present study ranged from 12.9 to 29.8 L kg−1, depending on exposure concentration. In summary, this study contributed to our knowledge of chemical dynamics in the FET test with embryolarval zebrafish, which will aid in defining suitable exposure conditions for future studies

New Insights into the Toxicokinetics of 3,4-Dichloroaniline in Early Life Stages of Zebrafish (Danio rerio)

In the fish embryo toxicity (FET) test with zebrafish (Danio rerio) embryos, 3,4-dichloroaniline (3,4-DCA) is often employed as a positive control substance. Previous studies have characterized bioconcentration and transformation of 3,4-DCA in this test under flow-through conditions. However, the dynamic changes of chemical concentrations in exposure media and embryos were not studied systematically under the commonly used semi-static exposure conditions in multiwell plates. To overcome these limitations, we conducted semi-static exposures experiments where embryolarval zebrafish were exposed to 0.5, 2.0, and 4.0 mg L−1 of 3,4-DCA for up to 120 hpf, with 24-h renewal intervals. During each renewal interval, concentrations of 3,4-DCA were quantified in water samples at 0, 6, 18, and 24 h using high-performance liquid chromatography with diode array detection. Levels of 3,4-DCA in larvae were measured after 120 h exposure. Concentrations of 3,4-DCA in the test vessels decreased rapidly during exposure. Taking these dynamics into account, bioconcentration factors in the present study ranged from 12.9 to 29.8 L kg−1, depending on exposure concentration. In summary, this study contributed to our knowledge of chemical dynamics in the FET test with embryolarval zebrafish, which will aid in defining suitable exposure conditions for future studies