Author

Alexis Aleman

Date of Award

8-2019

Degree Type

Honors College Thesis

Department

Biological Sciences

First Advisor

Alex Flynt, Ph.D.

Advisor Department

Biological Sciences

Abstract

RNA interference, referred to as RNAi, is a biological phenomenon whereby knock-down of gene expression can be achieved through the use of RNA molecules, including small interfering RNAs (siRNAs) and microRNAs (miRNAs). The use of miRNAs is an endogenous pathway that results in the degradation of the miRNA strand’s complementary messenger RNA (mRNA), preventing the translation of the mRNA and therefore the production of the proteins necessary for gene expression. While RNAi is a biological phenomenon that occurs naturally, it is also a method that can be used and manipulated in the laboratory to try to control the expression of genes associated with various issues. One such problem that has been studied using RNAi is pest control. One of the most destructive pests to crops globally is the whitefly, Bemisia tabaci. RNAi has produced the best results in B. tabaci when double-stranded RNAs (dsRNAs) are fed to the fly. In order to better understand miRNA evolution and to examine the process of miRNA-mediated mRNA degradation via RNAi in the whitefly, a miRDeep analysis was performed on the genome of Bemisia tabaci to identify miRNAs. Doing so allowed for the identification of 41 novel miRNAs and a total of 177 confidently assigned miRNAs in the whitefly. Of the novel miRNAs discovered, 83% were monocistronic, and the 177 confidently assigned miRNAs were predicted to regulate 51% of the mRNAs in the whitefly, consistent with the findings of previous studies. The ten mRNAs that are targeted the most by miRNAs in the whitefly play serious roles in medicine, including coding for a brain tumor protein, pointing to the clinical significance of further investigating the RNAi pathways in these genes. In addition, of the 51% of the whitefly’s mRNAs that were predicted to be regulated by miRNAs, 4% were discovered to be targeted by 100 or more miRNAs, indicating numerous RNAi pathways that can be further studied and analyzed in order to better control the expression of these genes.

Available for download on Wednesday, September 23, 2020

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