Document Type

Senior Thesis

Publication Date

Spring 2025

Committee Chair

Thomas Hammond

Committee Member

Kyle Floyd

Abstract

Neurospora crassa is a well-known model organism for studying eukaryotic genetics, particularly non-Mendelian inheritance mechanisms such as meiotic drive. In N. crassa, meiotic drive can be observed in fungal spore killing, where Spore killer-3 (Sk-3) is a selfish genetic element transmitted to offspring through spore killing. Sk-3 is thought to contain two principal components: a killer (poison) gene and a resistance (antidote) gene. While the resistance gene (rsk) has been identified, the killer gene remains unknown. Building on previous research that identified a 1.3 kb DNA interval (i350) essential for Sk-3-based spore killing, I analyzed two subintervals, i382 and i400, to narrow down the functional components of the Sk-3 locus. Deletion of i382 does not disrupt spore killing and deletion of interval i400 partially disrupts spore killing but does not eliminate it. Future work should retest the i400 strains in spore killing assays, to determine if the partial spore killing phenotype can be detected in all crosses when larger numbers of rosettes are examined. The findings presented here help narrow down the search for the unknown poison gene involved in spore killing, which is a critical step towards understanding processes that allow for the evolution of Sk-3-type selfish genetic elements.

Funding Source

This work was supported by the National Science Foundation (Award Number 200595, Elucidating the mechanism of meiotic drive by mRNA editing-mediated spore killing in Neurospora fungi) and the ISU BirdFEEDER Program Fund.

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