RNA interference (RNAi) and CRISPR/Cas9-genome editing have revolutionized biology by enabling loss-of-function analyses with relatively simple procedures. Although both RNAi and CRISPR/Cas9 lead to functional loss of the targeted gene, these two methods are fundamentally different. RNAi targets mRNA at the post-transcriptional level, leading to the reduction (i.e. knockdown) of the target gene function. On the other hand, CRISPR/Cas9 modifies the gene within the genome, enabling the elimination (i.e. knockout) of the target gene function. We hypothesize that these two loss-of-function approaches induce distinct phenotypes when applied to particular tissues. More specifically RNAi leads to varying degrees of phenotypic severity among cells of an individual as well as among individuals, while CRISPR/Cas9 results in a mosaic of normal and complete loss-of-function phenotypes within an individual. In the fruit fly (Drosophila melanogaster), one of the most established genetic model systems, both RNAi and CRISPR/Cas9 can be used in a spatially and temporally controlled manner. In this project, we will target several genes important for the formation of the wing in Drosophila to evaluate this hypothesis. Our preliminary results targeting genes, vestigial (vg) and Ultrabithorax (Ubx), suggest that the outcomes of the two methods are indeed distinct. vg RNAi produced varying degrees of wing reduction, while CRISPR/Cas9 yielded less variation, resulting in either no wings or unaffected phenotypes. Ubx RNAi produced varying extents of a second set of wings, while CRISPR/Cas9 produced less variation. These outcomes have important implications when selecting the appropriate technique in genetics research as well as potential medical applications.
Author(s): El Chetty and Yoshinori Tomoyasu, Biology PhD
Advisor(s): Yoshinori Tomoyasu, Biology
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