2012 Theses Doctoral

Studies of a Site-Specific Recombination System and Analysis of New Modulators of Notch Signaling in C. elegans

Vargas, Marcus L.

The ability to make transgenic animals has been a great tool for biologists to study living organisms. In C. elegans, the way transgenes are generated makes them problematic in many circumstances, and there is no single, simple, reliable approach that circumvents all of the problems with current methods of introducing transgenes into C. elegans. In Chapter 2, I discuss my attempt to develop a transgenic system in C. elegans using the bacteriophage phiC31 integrase system. I show evidence that phiC31 integrase is active in C. elegans somatic tissue. I have successfully integrated a transgene into the C. elegans genome in single-copy using phiC31 dependent recombination-mediated cassette exchange. However, attempts to repeat phiC31-mediated integration has been unsuccessful.
In Chapter 3, I use genetic analysis to test many genes that were reported to be associated with the gamma-secretase complex in a mammalian tissue culture system. The gamma-secretase complex is an important component in the Notch signaling pathway. Not only is the gamma-secretase complex essential in the Notch pathway, it is also implicated in the pathology of familial Alzeheimer's disease (FAD). As gamma-secretase complex components show a Notch loss-of-function phenotype in C. elegans, a reverse genetic approach, using genes encoding proteins that associate with Presenilin was used to identify putative new Notch modulators. Several genes were identified that suppress a glp-1(gf) allele and one gene that suppress a gfp-1(lf) allele. These genes are unlikely to be core components of the Notch signaling pathway.