Vargula tsujii is a small marine crustacean that belongs to the class Ostracoda. These organisms can produce bioluminescence for courtship or as a defense mechanism, and this is accomplished by an enzyme called luciferase (Luc). Recent molecular studies show that there is a gene named soroluciferase (SoroLuc) that has many sequence similarities to Luc, but as of yet, has not been completely isolated or functionally characterized. By identifying the SoroLuc sequence, and testing its function, we can test theories about how these closely related genes evolved the ability to produce bioluminescence. Our first step in the process consists of isolating the two genes of interest from cDNA of individual animals. Using plasmids obtained from E. coli, we will complete a restriction enzyme digestion cloning and ligation in order to incorporate our genes within the plasmid sequence. To obtain large concentrations of our expressed proteins from these genes, we will then insert our newly constructed fusion plasmids into Pichia pastoralis. Unlike E. coli, this eukaryotic expression vector is able to translate both Luc and SoroLuc with the proper post-translational modifications in order to assess variation in function between these genes. To determine if SoroLuc has similar enzymatic function to Luc, we can add the substrate luciferin to both isolated proteins and measure their ability to produce light. This study will help us to understand how genes that are closely related gain new functions.