Student: Samantha Cote, Sheena Mendez and Milly Panicker
Mentor: Professor Suzanne Deschenes
Major: Biology

Mismatch repair (MMR) is the DNA repair system that identifies and corrects insertions, deletions, and base substitutions that arise during DNA replication, as well as those induced by environmental mutagens. Sodium nitrite, commonly found in hot dogs and other processed meats, can deaminate bases. When a base is deaminated, DNA polymerase may incorrectly pair bases together, which over a series of replications can produce a mutation. Endonuclease V (Endo V), encoded by the nfi gene, detects and excises deaminated bases to avoid mutations. We hypothesize that MMR may also repair mismatches involving deaminated bases in DNA. To test this hypothesis, the lacZ reversion assay in E. coli is being used to determine the type and frequency of NA-induced mutations in strains that are deficient in MMR, Endo V, or both MMR and Endo V. Previously, an nfi mutation was introduced into lacZ reversion strains. To confirm the Endo V-deficient genotypes and phenotypes of these strains we used previously published protocols, including a method for performing nitrite and nitrate mutagenesis under micro-aerobic growth conditions.  The data confirmed the expected mutation phenotype of CC106?nfi.  Data from ongoing studies with other Endo V-deficient strains will also be presented.

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