DOI

10.30707/1734536653.457732

Document Type

Senior Thesis

Publication Date

Spring 2024

Committee Chair

Thomas Hammond

Committee Member

Pirmin Nietlisbach

Abstract

Some isolates of the fungus Neurospora crassa possess a chromosomal factor that causes spore killing, leading to death of ascospores. It has been shown that these chromosomal factors are genetic elements called spore killers. For example, if a cross is performed between a parent with an Sk-S (sensitive) allele and a parent with an Sk-K (killer) allele, the cross will produce half viable offspring and half inviable offspring, where the inviable half has been killed by spore killing. This phenomenon can be explained by meiotic drive, wherein a selfish gene disrupts the randomness of sexual transmission, favoring its own success. In this study, I focus on a Neurospora Spore killer known as Sk-3. Sk-3 is thought to possess both a killer element and a resistance element. The resistance element is rsk, a gene that keeps ascospores alive and viable when in the presence of the killer element. However, the mechanism by which the killer element kills ascospores is unknown. A major obstacle to studying the killing mechanism is that the identity of the Sk-3 killer element itself has remained elusive. My goal is to help identify the Sk-3 killer element. Preliminary results by others have narrowed the search to the left arm of Chromosome III. These results have also shown that deletion of a 1.3 kb DNA interval, called v350, causes loss of spore killing. This suggests that a regulatory element, or a hidden gene, may overlap with the v350 interval. To help determine why v350 deletion correlates with loss of spore killing, I investigated a related DNA interval, called v384. My results suggest that v384, like v350, is required for spore killing.

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).

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