Abteilung Umwelttoxikologie

Background
Chemical pollution in aquatic ecosystems is recognized as a major environmental threat, resulting in significant alterations to aquatic biodiversity. However, organisms are equipped with different mechanisms of defense that allow species to cope with chemical exposure. Among these mechanisms, biotransformation processes are of particular importance due to their role in detoxification and in reducing the bioaccumulation potential of chemicals. Nonetheless, previous studies in fish suggest that biotransformation ability differs significantly among taxonomic groups, leading to differential sensitivity to pollution across species.
Recently, the moderlieschen (Leucaspius delineatus) has been proposed as a potential model species in ecotoxicology, as it corresponds to an endemic fish species inhabiting temperate ecosystems in Europe with significant ecological value. However, almost no information exists regarding the performance and sensitivity of this fish species when challenged with chemical exposure. Therefore, this project aims to gain insight into the biotransformation ability of the moderlieschen and advance its applicability in assessing responses to chemical exposure in fish.

Aim
Determine the biotransformation ability of the moderlieschen (Leucaspius delineatus) towards micropollutants (e.g. pharmaceuticals and pesticides) using well-established in vitro methodologies.

Methods
The proposed project is established at the interface of toxicology, chemistry, cell biology, and ecology, and aims to implement well-established in vitro systems for the evaluation of biotransformation ability.
The activity of different biotransformation pathways will be evaluated by determining chemical clearance rates of select micropollutants, including pharmaceuticals and pesticides. Chemical clearance will be estimated via substrate depletion experiments using S9 sub-cellular (enzymatic) fractions isolated from fresh tissue as well as from cell lines established from the moderlieschen. Chemical analyses will be then conducted using state-of-the-art instrumentation, including high performance liquid chromatography (HPLC) coupled with high-resolution mass spectrometry (HRMS).
The methodologies in the proposed work will involve (i) isolation of enzymatic fractions, (ii) routine cell culture techniques, (iii) protein quantification, (iv) spectrophotometry, and (v) instrumental analysis (e.g. HPLC-HRMS).
Suitable candidates for this project are expected to hold a bachelor (BSc) degree in chemistry, biology, biochemistry, environmental science, or a related discipline. Moreover, candidates should have a strong interest for advancing animal alternatives in (eco)toxicology.
If you wish to apply, please send your most recent CV to Dr. Marco E. Franco. This work will be performed at the Department of Environmental Toxicology at Eawag in Dübendorf, Switzerland.

Background
Chemical pollutants in water bodies pose a major environmental threat. Among other effects, they can affect the neurophysiology of aquatic organisms, impairing their chances of survival. Neuroactive chemicals specifically act on key central nervous system molecules, leading to adverse neurological effects. Current environmental risk assessment of neurotoxicity still largely relies on fish testing, which is not only time- and resource-intensive but also focuses primarily on behavioral changes and mortality, without providing mechanistic insights into neurotoxic effects. Here, we propose a rainbow trout (Oncorhynchus mykiss) brain cell line (RTbrain) as an animal-free alternative for the neurotoxicity assessment of environmental pollutants.

Aim
This project aims to evaluate the neurotoxic effects of chemicals using our in vitro fish brain cell-based model, with the goal of selecting and validating bioassays for neurotoxicity screening

Methods
The student will conduct experiments on the RTbrain cell line to evaluate various neurotoxicological endpoints, analyze cellular responses, and contribute to the development of a comprehensive in vitro neurotoxicity testing battery. Through this project, the student will gain hands-on experience in cell culture techniques, and learn to perform different in vitro toxicity assays using a set of chemicals (e.g. pharmaceuticals and pesticides) with different mechanisms of neurotoxicity. The bioassays include multi-endpoint cytotoxicity techniques (evaluating changes in metabolic activity, membrane integrity and lysosome function), gene expression analysis (RT-qPCR) to investigate molecular responses, and cellular staining with fluorescent microscopy for visualizing specific cellular changes.

Suitable candidates for this project should have an interest in toxicology and in advancing alternative to animal testing in research. The student is expected to have a background in environmental science, biology, biochemistry or related disciplines. Prior laboratory experience is a plus.

If you are interested in joining this project, please contact Jessica Bertoli or Colette vom Berg  This work will be performed at Eawag at the Department of Environmental Toxicology in Dübendorf.