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%0 Thesis
%A Di Paolo, Carolina
%T Mechanism-specific toxicity bioassays for water quality assessment and effect-directed analysis
%I RWTH Aachen University
%V Dissertation
%C Aachen
%M RWTH-2016-08695
%P 1 Online-Ressource (xxvi, 273 Seiten) : Illustrationen, Diagramme, Karten
%D 2016
%Z Veröffentlicht auf dem Publikationsserver der RWTH Aachen University
%Z Dissertation, RWTH Aachen University, 2016
%X Biological assays have been applied to investigate freshwater quality for more than a century, and the public awareness of the threats of aquatic pollution has motivated advances in water quality regulations. In Europe, such a scenario led to the establishment of the Water Framework Directive (WFD) as a unified and harmonised framework for water protection, with the main objective to achieve a good water ecological and chemical status. Despite the recognized relevance of bioassays by scientists and national authorities, until now they are not recommended for direct application in the WFD monitoring activities. A reason for that is that there are remaining research questions that need further clarification before bioassays are integrated in water quality monitoring.The EDA-EMERGE Marie Curie Initial Training Network, in which context the present thesis was developed, was set up to investigate and answer some of these questions. The project aimed at the assessment, monitoring and management of water quality in European river basins through different approaches, including the investigation and development of new effect-directed analysis (EDA) methods for the identification of toxicants in surface waters. For that, new bioanalytical, chemical and hyphenated methods were developed. In this thesis, mechanism-specific bioassays were newly developed, advanced or adapted for the assessment of emerging pollutants or water samples, and as guiding tools in EDA investigations. The research questions guiding this thesis were: (i) How can mechanism-specific bioassays adequately be integrated into EDA?; (ii) How to advance aquatic relevant mechanism-specific bioassays?; (iii) Are mechanism-specific bioassays able to properly evaluate emerging pollutants as single compounds and as mixtures?; and (iv) How to efficiently apply bioassay battery approaches and what are their benefits for the water quality assessment? In order to answer these questions, the overall objectives of this thesis were: (1) To adapt bioassay protocols and develop respective testing strategies for application as guiding tools in EDA studies; (2) To develop aquatic relevant mechanism-specific bioassays utilizing zebrafish early life stages and zebrafish liver cell lines; (3) To evaluate the effects of emerging pollutants as single chemicals and as mixtures on aquatic organisms and in vitro bioassays; and (4) To apply and evaluate bioassays and bioassay battery approaches to investigate water sample extracts and emerging aquatic pollutants. These objectives were explored in complementary studies focusing on bioassay development and adaptation, followed by the application of bioassays to evaluate diverse aquatic pollutants and water samples, and ultimately leading to a comprehensive multi-organism and multi-mechanism aquatic toxicity assessment approach. In parallel, other activities were developed in the context of the project, including an intensive training in EDA-related methods and a joint monitoring study for evaluating water samples from different European river basins in bioassays and chemicals analysis.Initially, a literature review provided an overview of EDA investigations that applied bioassays with zebrafish as guiding tools, with mechanism-specific bioassays being identified as particularly useful for EDA investigations. Subsequently, mechanism-specific assays with zebrafish models were developed in the context of this thesis. One study focused on the development of a new method to evaluate chronic, delayed toxicity using zebrafish early life stages, which also identified early endpoints that can potentially predict later effects. Another study developed protocols to evaluate micronucleus occurrence in a zebrafish liver cell line and zebrafish larvae as a robust genotoxicity endpoint, and applied the methods to investigate genotoxic compounds. Further, the effects of neuroactive and neurotoxic compounds on the behavioural response of zebrafish larvae following a light-dark transition stimulus were also investigated. Additionally, antiandrogenicity and the induction of the p53 protein pathway were assessed by using respective reporter gene cell-based assays. A testing strategy utilizing the p53 assay and a bioassay for cell viability assessment was applied to investigate genotoxic compounds as single exposures and mixtures. Antiandrogenicity assessment of surface water samples identified a particularly active sample, which was selected for a follow-up EDA investigation. Since only a limited sample volume was left, downscaled methods of dosing and exposure procedures had to be developed and validated using model (anti)androgenic compounds. Afterwards, the developed tools were applied in the EDA study. Finally, an interlaboratory study involving different collaborating partners was organized within this PhD project. A basic bioassay battery containing organism-level and in vitro mechanism-specific assays was applied to investigate a pristine water extract spiked with emerging pollutants as single chemicals or mixtures. This study is expected to support and promote the use of a basic bioassay battery for water quality monitoring.In summary, this thesis developed new and improved existing bioassays and bioassay testing strategies for future mechanism-specific toxicity investigations of aquatic emerging pollutants, chemical mixtures or water samples; or as guiding tools in effect-directed analysis.
%F PUB:(DE-HGF)11
%9 Dissertation / PhD Thesis
%U https://publications.rwth-aachen.de/record/673445