Colorado College Logo


Use AND (in capitals) to search multiple keywords.
Example: harmonica AND cobos

RNAi induced knockout of zif-1 and of elc-1 E3 ubiquitin ligases affects MEX-3 protein localization during embryo development of Caenorhabditis elegans

by Heng, Peter


PAL-1 is a protein that regulates posterior development of Caenorhabditis elegans embryos. Although pal-1 mRNA is present throughout the entire embryo, the PAL-1 protein is only transcribed in the posterior end of the nematode worm. MEX-3, a RNA binding protein, binds to the pal-1 mRNA, preventing its translation in the anterior section of the embryo. The MEX-3 protein is essential to maintaining embryo polarity and ensuring that posterior features develop only in the posterior end of the worm. During development, MEX-3 is present throughout the 1-cell and 2-cell embryo stage. MEX-3 is then degraded in the posterior end during the 4-cell stage, allowing the expression of PAL-1 in the two posterior blastomeres. By the 8-cell stage, MEX-3 is depleted from the entire embryo with remnants remaining in germline cells. The ubiquitination pathway is hypothesized to mark MEX-3 for degradation, localizing the protein at various stages of embryo development. This study screened various E3 ubiquitin ligases to determine which ligases are specifically used to mark MEX-3 for degradation during embryo development. Double-stranded RNA was created for selected E3 ubiquitin ligases and then injected into adult worms. This invoked RNA interference (RNAi) of these ubiquitin ligases in the embryos of the adult worms. Knockout of genes D2089.2, F46A9.5, F59B2.6, and Y82E9BR.15 resulted in embryonic lethality. Fluorescence microscopy of GFP::MEX-3 (green fluorescent protein labeled MEX-3) revealed that only F59B2.6 (zif-1 gene) and Y82E9BR.15 (elc-1 gene) knockouts affected MEX-3 localization. Double knockouts of zif-1 and another developmental gene, mex-5, support the hypothesis that zif-1 acts after other regulatory events in MEX-3 localization.


Colorado College Honor Code upheld.

Includes bibliographical references.

Administrative Notes

Colorado College Honor Code upheld.

Copyright restrictions apply.
Colorado College
Digital Origin
born digital
45 pages : illustrations (some color)
Senior Thesis -- Colorado College
Thesis Advisor
Huang, Nancy Bower, Nathan
Degree Name
Degree Type
Bachelor of Arts
Degree Grantor
Colorado College
Date Issued