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Use of the molecular technique RNA interference (RNAi) has been an important tool in establishing gene function in model organisms such as planaria. Two methods are commonly used in planarian research to conduct RNAi: microinjection and feeding. Each have their respective strengths and weaknesses, with microinjection being very precise, and feeding allowing for large scale genetic screens. In the planarian literature these two methods are used interchangeably, however, no research has specifically compared the efficacy of both methods. In this study, I explore the phenotypic results obtained from both microinjection and feeding. Using genes identified from the literature that have established microinjection phenotypes, I compared these phenotypes to ones I obtained using the feeding method. My results showed that microinjection and feeding of glutamic acid decarboxylase (gad) RNAi produced similar effects (diminished light aversive behavior). Conversely, while microinjection of tyrosine hydrolase (th) RNAi was found to result in locomotive defects, my results showed that feeding produced cyclopic eye formation and altered surface adhesion instead. Lastly, the reported phenotype from the knockdown of the planar cell polarity (PCP) pathway via microinjection was neural hyperplasia and ectopic eye growth. However, the RNAi feeding method of PCP knockdown almost completely attenuated this phenotype. Together, these results indicate that RNAi microinjection and the feeding of RNAi do not necessarily produce comparable results.
Watson, Gabrielle, "Comparing RNA Interference Methods in Planarians" (2018). Honors Theses. 2984.