UC Riverside

This thesis examines the mechanisms of class II DNA transposon activity and the genomic defense system against transposons in two Dipteran systems, Drosophila melanogaster and Aedes aegypti. The first half of the dissertation focuses on the affects specific amino acid changes have on target site specificity and transposition activity. Specifically it looks at AeBuster1 and piggyBac mutants. None of the Aebuster1 mutants were found to have increased transposition activity however several mutants had altered target site specificity. One piggyBac mutant hyPBase, which has been shown to have increased activity in HeLA cells, mouse somatic cells and yeast, was studied in-depth. My study determined that hyPBase does not maintain its increased activity in Dipteran systems and significantly increases sterility rates when compared to wild type piggyBac. The second half of the thesis focuses on investigating the piRNA system in the important disease vector Ae. aegypti. The piRNA pathway is a Dicer independent small RNA pathway believed to be responsible for transposon control. In this study I examined the expression of 7 PIWI proteins and studied three of them, AGO3, PIWI2 and PIWI7 using co-immunoprecipitation and RNAi knockdown. Together all of these studies provide insight into transposition mechanisms and transposon control in D. melanogaster and Ae. aegypti.