Department Environmental Toxicology

Fish intestine as organism-environment barrier

Cellular epithelia are gate keepers that regulate the interaction of an organism with its surrounding environment. The intestinal epithelium is an example of an environment-organism barrier that regulates uptake from food and at the same time it provides protection from environmental toxicants and pathogens. Investigations regarding the intestinal barrier functions are fundamental to fish physiology, aquaculture, environmental toxicology and chemical regulation. Thus far, the investigations are limited due to the restricted accessibility of the intestine.

The role of the fish intestine is investigated in vitro using the intestinal epithelial cell line RTgutGC, isolated from rainbow trout (Onchorhynchus mykiss). The cells are cultivated on permeable supports, which creates a two-compartment model. This setup is suitable to investigate transport processes of external stressors found in the aquatic environment, such as metals, nanoparticles (see “Interaction of nanoparticles with fish cells”) and chemicals. Here, specifically persistent, hydrophobic chemicals are of concern, since when present in water, such substances can adsorb to particles and might be taken up by the oral route. Using commercially available permeable supports, the physical and immunological barrier function of the RTgut-GC monolayer is investigated. As an example, the permeation of chemicals as a measure of their bioaccumulation potential is evaluated. (PhD project H. Schug).             
Moreover, the in vitro system can be adapted to naturally occurring environmental changes, such as temperature, pH and salinity. Recreating the intestinal microenvironment on a microchip is a new approach to study the interaction of different intestinal cell types and to allow for realistic, biologically relevant exposure and transport phenomena using microfluidics (PhD project C. Drieschner).