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Virulence of the opportunistic fungal pathogen Candida albicans is influenced by its ability to switch from budding yeast to hyphal forms. The yeast-to-hypha switch is partially regulated by the asymmetric transport of messenger RNA transcripts that encode growth proteins and virulence factors. The She3 protein is a key component in a C. albicans mRNA transport complex. My project sought to better understand Candida albicans She3 function by investigating its role in pseudohyphal growth, and mRNA transport by extension, of Saccharomyces cerevisiae. I designed plasmids containing C. albicans or S. cerevisiae SHE3 under the control of the S. cerevisiae SHE3 promoter and transformed she3Δ/ she3Δ and wild-type S. cerevisiae cells. The smaller URA3 vector had greater transformation efficiency than the SHE3-containing plasmids. Transformants were assayed on low-nitrogen pseudohyphal growth-inducing medium. Pseudohyphal growth was slower than anticipated, and differences in filamentation between the different strains were subtle. Wild-type cells that expressed ScSHE3 from both the chromosome and plasmid manifested more pseudohyphal growth than those with only chromosomal expression. Higher concentrations of yeast nitrogen base decreased pseudohyphal growth of she3Δ/she3Δ cells with the CaSHE3 plasmid. Contrary to expectations, wild-type cells showed equivalent or less filamentation than she3Δ/ she3Δ cells, and the she3Δ/ she3Δ cells bearing the SHE3 plasmids showed equivalent or less filamentation than she3Δ/ she3Δ cells with the URA3 vector. This assay and two novel plasmids from this study can be employed in future studies to further explore CaShe3 function. Characterization of CaShe3 may provide new avenues for counteracting C. albicans infection.
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