Submission Date


Document Type

Paper- Restricted to Campus Access




Rebecca Lyczak

Committee Member

Rebecca Lyczak

Committee Member

Mark Ellison

Committee Member

Simara Price

Department Chair

Peter Small

Project Description

In C. elegans early embryonic development, the anterior-posterior axis is established. This establishment is created by the sperm-donated centrosome contacting the posterior cortex of the cell, causing a series of events to occur. The PAR proteins and actomyosin cytoskeleton localize to either the posterior or anterior cortex of the one-celled embryo. Thus, the first division of the cell is asymmetric, creating two different daughter cells. PAM-1, a puromycin-sensitive aminopeptidase, is needed for proper movement of the centrosome. In pam-1 mutants, cells fail to polarize, creating a symmetric first division and leading to high rates of embryonic death. The importance of PAM-1 in early embryonic division is clear, yet pathways and targets of PAM-1 are still unclear. To gather more information about the targets and genes that interact with pam-1, suppressors of pam-1 were identified by randomly mutagenizing the genome of the pam-1 worms. These suppressors increase the hatch rate of embryos and restore the wild-type phenotype. We have identified many suppressors to date, but I work with lz5, a suppressor that hatches at 35% when there is both a pam-1(or347) mutation and an additional lz5 mutation somewhere in the genome. Mapping lines of lz5 were created, and through SNP mapping we were able to identify a region of the C. elegans genome where our lz5 suppressor gene could be located. These strains were sent for whole genome sequencing and a list was compiled of the candidate lz5 suppressor genes. Through RNA interference hatch tests, I was successfully able to narrow down the candidate suppressor gene list from fourteen to three candidate genes, located on chromosome II in the C. elegans genome. I was also able to create a strain of worms that contained the lz5 suppressor mutation without the homozygous pam-1 mutation. This strain can be used to analyze the phenotype of the lz5 gene without the presence of pam-1. Complementation crosses can also be performed between our lz5 strain and mutant strains of the candidate gene for phenotype analysis and comparison. RNAi experiments and complementation crosses will provide a better understanding of the remaining candidate suppressor genes. Once the suppressor gene is identified, it will help in determining the exact role that PAM-1 and its target play in anterior-posterior axis establishment.