Department Environmental Toxicology

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.