Tonight I watched another JMBE Live session with Greg Phillips from the University of Georgia and Nancy Boury from Iowa State University. Stanley Maloy, Editor in Chief of JMBE, was the moderator. Maloy spoke about how this Curriculum article revisits the Central Dogma. Boury and Phillips were together for several years at Iowa State. The title of their session was “Teaching an old dogma new new tricks?.” The article in JMBE is “Changing colors and understanding: the use of mutant chromogenic protein and information suppressor strains…” The illustrations of the article were done as an independent study as part of the medical illustration program! Boury noted that “The Central Dogma of molecular biology is foundation, but often only vaguely understood.” In Boury’s research and surveying 200+ students, 50% had misconceptions. Boury asked the audience: what do your students struggle with most? People mentioned terminology, details… Phillips explained how chromogenic proteins (CP) absorb light and can be seen. The synthetic gene encoding chromogenic protein for the coral Acropora millepora was codon optimized for expression in E. coli. the CP was expressed from a recombinant plasmid under control of the rhamnose promoter. Phillips has also done mutagenesis and used CP as a teaching tool. The CP has a 3D structure similar to GFP: a barrel. Interestingly, amino acid 62 alters the color phenotype! Several colors are visible. Boury explained that they used backward design to use these constructs as tools for teaching the Central Dogma. Boury listed the three student learning objectives they designed for this lab exercise. These were aligned with the Fundamental Statements for ASM Curriculum Guidelines and the Genetics Society of America. Phillips spoke about E. coli suppressors strains that insert an amino acid at the position of amber (UAG) stop codon. The title of the slide was telling: “Changing the DNA (genotype) isn’t the only way to change the protein (phenotype), however.” The team selected five strains with different tRNA. The broth/colony changed. Students received the same plasmid and introduced it into five strains. Students did a pre lab and a post lab. The class size was 16-18 per semester. Students transformed the plasmid with the nonsense suppressor. Students also learned about expression induction by rhamnose. The lab ended with discussion questions and a lab report. Boury emphasized that suppression is a mutation but at the tRNA level! Boury shared results of Wilcoxon signed-rank test for several semesters on pre-/post-tests. The normalized learning gains (NLG) were 0.14. Boury explained that the NLG = (Post-Pre)/(100%-Pre). Phillips shared the constructs on Addgene. Other options with these constructs are: gene expression, mutagenesis, protein structure/function, and biosensors. Phillips did note that whole plasmid sequencing can be used. Boury spoke about using the normalized learning gains for sharing data. Maloy asked about scaling up, and Phillips said that you can get a lot of mileage with toothpicks and and plates. Boury talked about how the collaboration started that began with refining the objectives and pieces of the lesson. One question asked by the audience was if the activity would be suitable for second-year students. Phillips said it would be, and Maloy noted that gains may be even higher.
