Identifying the genetic determinants of chemical toxicity in the green alga Chlamydomonas reinhardtii

For thousands of chemicals that are found in our environment little or no toxicological data are available. Current regulations, which are focused on physiological endpoints, are not suitable for the number of chemicals that require testing; the consensus of the (eco)toxicological research community is that a shift towards a more molecular mechanism-based, high-throughput toxicological testing is needed. The goal of the proposed research is to develop a method for assessing toxicological properties of chemicals, based on functional genomic screening of a pooled loss-of-function mutant library of the green alga Chlamydomonas reinhardtii and next-generation sequencing. C. reinhardtii was chosen as the model species based on the availability of the mutant library, existence of a well annotated genomic sequence, relative ease of cultivation and rapid growth, which will enable simultaneous screening of a large number of chemicals. The functional genomic profiles obtained after chemical exposure will serve as basis to (i) identify genetic determinants of tolerance and sensitivity to environmental chemicals, (ii) find and annotate as yet uncharacterized genes involved in chemical toxicity and (iii) classify the chemicals according to their mode of action. By screening a large number of chemicals of different chemical classes and combining the newly obtained and existing knowledge, a comprehensive set of chemical toxicity pathways and several adverse outcome pathways for C. reinhardtii will be developed, and shared with the research community in public databases (eg http://aopkb.org/). The project will draw from recent advances in molecular biology, sequencing and bioinformatics to develop high-quality resources and tools that will enable prioritization of chemical testing and accelerate the development of new mechanism based toxicological assays, thus contributing to a more objective and efficient assessment of chemical risk to the environment.