Cancer and chemicals: A research-inspired laboratory exercise based on the Ames test for mutagenicity

Laboratory courses should cultivate enthusiasm for research and an appreciation for real-world scientific challenges to retain undergraduate students and encourage them to pursue STEM-related careers. Course-based undergraduate research experiences (CURE) have emerged as an inclusive pedagogical model that facilitates laboratory skill development, while also improving self-efficacy and critical thinking skills. Herein, an innovative research-inspired Ames test for mutagenicity project is described. Students choose their own project theme and investigate substances using both TA98 and TA100 strains of Salmonella typhimurium to evaluate the potential for frameshift mutations and base-pair substitutions, respectively. An appropriate test concentration of each substance is first determined via a cytotoxicity assay, providing an additional learning opportunity. Students also study the mutagenicity of test substance metabolites using commercially available rat liver extracts to simulate metabolism. Overall, these experiences provide a comprehensive research project with high relevancy to human health and real-world importance. This laboratory module was assessed using CURE pre- and post-course surveys to evaluate learning gains and benefits. Assessment data illustrated that students appreciated the discovery aspect of the research project and gained skills related to reading scientific literature and effective poster presentations. Student-reported benefits of research project participation included learning new laboratory techniques, enhanced scientific writing skills, an increased tolerance for and understanding of common research challenges, and the confidence to tackle more complex research endeavors. Narrative feedback from students was very positive, with project highlights being the opportunity to select their own test substances and create new knowledge, as well as the analysis of results.