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In the nematode Caenorhabdatis elegans, anterior-posterior (AP) axis formation in the single-cell embryo is indicative of cell polarity, which is essential for the achievement of future functional potential. AP axis polarization is initiated by the contact of the sperm-donated centrosome with the posterior cortex of the embryo. The contact results in a destabilization of the actomyosin cytoskeleton, initiating polarization. Events such as cortical flow, symmetry breaking, and pseudocleavage are necessary for the completion of AP axis formation and ultimately asymmetric cell division. The centrosome prematurely departing from the posterior cortex causes a disruption in PAR protein localization, thus disrupting AP axis formation. PAM-1, a puromycin-sensitive aminopeptidase, is involved in polarization by preventing premature movement of the centrosome from the posterior cortex. pam-1 mutants lack a functional PAM-1 protein, and therefore lose its centrosome-cortex stabilization effect. Without this stabilization, pam-1 mutants exhibit a series of abnormalities culminating in the failure to establish proper AP axis polarization, resulting in symmetric division. Thus, pam-1 is typically lethal. However, our lab has identified 5 suppressor mutations, (lz1-5) of pam-1, which significantly decrease lethality by restoring the normal phenotype. I aimed to validate previous research describing the chromosomal location of the lz4 suppressor and to investigate suppressor polarity establishment using confocal microscopy. I employed RNA interference (RNAi) after whole genome sequencing in order to validate the chromosomal location. In addition, I crossed different strains of C. elegans together, in order to create a strain that contains the lz4 suppressor and may be visualized using confocal microscopy. This new strain will allow me to investigate polarity establishment in suppressed strains.
Stephens, Dylan, "Identification of the lz4 Suppressor of pam-1 and its Role in Polarity Establishment in One-Cell C. elegans Embryos" (2016). Biology Summer Fellows. Paper 28.