Date of Award

Spring 2001

Document Type

Restricted Thesis

Terms of Use

© 2001 Margaret F. Lippincott. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts


Biology Department

First Advisor

Elizabeth Ann Vallen


Cytokinesis in Saccharomyces cerevisiae can occur via the contraction of an actomyosin ring or through septum formation. Although the actomyosin contractile ring is not essential, S. cerevisiae strains deleted for hof1, a gene important for septum formation, are dependent on the actomyosin contractile ring for cytokinesis and viability (Vallen et al. 2000). A screen for mutants synthetically lethal with hof1 was utilized to identify genes required for the function of the actomyosin pathway. Forty-one HOF1-dependent mutants were identified by screening 33,000 mutagenized colonies using a sectoring assay and other genetic tests. Genetic analysis suggests that the 34 recessive mutants fall into 18 complementation groups, 11 of which are single alleles. Seven mutants have dominant mutations or exhibit unlinked non-complementation; it is not yet known how many loci this represents. Complementation testing and plasmid-linked suppression indicates that three of the complementation groups are MYO1, BNI1, and CYK3. Interestingly, some of the myo1 and cyk3 mutants appear to exhibit unlinked non-complementation. Phenotypic analysis including Hoechst staining of DNA, rhodamine-phalliodin staining of the actin cytoskeleton, DIC microscopic analysis, and zymolyase treatment was used to characterize mutants. Results indicate that four mutants that may affect the actin-myosin pathway and cytokinesis are worthy of further analysis.