Paper- Restricted to Campus Access
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.
Schleicher, Emily M., "Identification of the lz5 Suppressor of pam-1 in Caenorhabditis elegans" (2016). Biology Honors Papers. 9.