SFP1 Control of Ribosome Biogenesis is Conserved in S. castellii

Mentors: Jenna Pfiffner & Dawn Thompson

To study the evolution of gene regulation, Sara compared expression patterns of ribosomal genes in two species of Ascomycota fungi. Sara focused her studies on genes regulated by the orthologs of the SFP1 gene in S. cerevisiae. In this yeast species, one SFP1 gene regulates cell size, the cell cycle, and ribosomal gene expression. However another Ascomycota species, S. castellii, has two SFP1 homologs. Sara explored the function of each paralog to ask if the regulatory functions of one or both are conserved.

Sara found that both S. castellii SFP1 mutants (Δ1a and Δ1b) yielded smaller colony sizes, and both mutants produced cells of reduced size. Growth curve analysis revealed that the Δ1b mutant grew much more slowly than the Δ1a mutant and wild-type. Both mutant strains exhibited reduced expression of ribosomal genes, but many more genes were down-regulated in the Δ1b mutant. Cell cycle genes were down-regulated in the Δ1b mutant, but up-regulated in the Δ1a mutant. Thus Sara’s findings point to both conserved and divergent roles of the two SFP1 genes in S. castellii.

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Sara, a senior at Brockton High School, compared roles of SFP1 in regulating cell cycle and ribosomal genes in different species of Ascomycota fungi.