Fish Model Species in Environmental Toxicology
Jessica Legradi and Juliette Legler, IVM Institute for Environmental Studies and Charles Tyler, University of Exeter
The large number of abstracts submitted on fish model species in environmental toxicology indicated that it is of wide interest to SETAC members, and this indeed proved to be the case. Presentations ran over the course of a full day with three sessions focused on mechanisms, endocrine disruption and exposure approaches. The work presented was derived from nine different countries spanning across Australia, America and Europe. This clearly shows the global interest of the use of fish model species in ecotoxicology. The applications of these fish models included chemical testing and focused mechanistic studies and addressed questions on population-level impacts of chemicals. A number of different fish model species were introduced in the session. As expected, the zebrafish (Danio rerio) was the most studied, with the medaka (Oryzias latipes) and fathead minnow (Pimephales promelas) also predominating. But other fish species were also presented as further models for addressing specific biological and ecotoxicological questions. Examples included the inland silverside (Menidia beryllina), which is a euryhaline species that can adapt to freshwater and saltwater conditions. Work showed that toxicants can have very different potencies depending on salinity, presenting different hazards for the same chemical in varying environments. Other species applied included the guppy (Poecilia reticulata), which has readily quantified behavioural features for use in toxicology, and the redtail splitfin (Xenotoca eiseni), which gives birth to live young and is being developed as a model to look at maternal transfer of toxicants.
Toxicological studies on a diverse range of chemicals were presented, such as pharmaceuticals, herbicides, pesticides, metals, PAHs and metabolites of brominated flame retardants. Mixture effects analyses were also presented including regimes for assessing effects of contaminated sediments. Molecular effects methods were a predominant feature in the work presented, most addressing in-depth mechanisms. The molecular methods included in vitro screening systems, many based around specific receptors. Transgenic models were a strong feature, and a range of exciting models were presented which not only allow for highly integrated health effects analyses but also better target effects tissue for more “intelligent” chemical testing and assessing of mixture effects. These systems also allow for assessing metabolically activated substances.
Most of the known toxicological mechanisms are conserved between fish species but also between fish and other vertebrates including mammals and even humans. This emphasizes the potential utility of fish model species not only for environmental toxicology but also for hazard identification in humans via read-across. As shown during the session, fish model species can be used to study effects from the molecular (e.g., gene activation, receptor binding) to population levels (e.g., behaviour, reproductive fitness). This strongly argues for their use to study and define adverse outcome pathways (AOPs). Analytical chemistry to quantify effect threshold concentrations in target tissues was identified as a research and development priority. This will enable better cross-species comparisons of responsiveness and sensitivity.
We found the session to be a great success, with excellent science, wide interest and good audience engagement. It also helped to highlight the huge potential of fish models in advanced and progressive ecotoxicology. We hope that this session will become a regular session of SETAC in the coming years. To summarize, fish model species are one of the most functional “multi-tools” available, well suited for adapting them to address a wide variety of environmental toxicology problems.
Authors’ contact information: firstname.lastname@example.org, email@example.com and C.R.Tyler@exeter.ac.uk
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