Dissertations, Theses, and Capstone Projects

Date of Degree

2013

Document Type

Dissertation

Degree Name

Ph.D.

Program

Biology

Advisor

James T. Nishiura

Committee Members

Peter N. Lipke

Barbara Studamire

Diana P. Bratu

Edward B. Dubrovsky

Subject Categories

Biology

Abstract

Transcription factors, microRNAs and RNA binding factors frequently interact to coordinate gene expression during development. The transcription factor BROAD (BR) is a global regulator of insect gene transcription and governs the timing of the commitment to pupate. I determined BR expression in the Ae. aegypti midgut by qPCR, and correlated its expression with that of nine miRNAs and three RNA-binding factors. During midgut metamorphosis the expression of these factors was dynamic and reproducible.

To better understand the changes in expression patterns, I evaluated the effects of hormone analogs on expression. Using this approach I uncovered concurrent up-regulation of BR, miR-34 and miR-14 in the pupal midgut when treated with methoprene, and found that RH2485 accelerated expression of BR, BRAT, and microRNAs let-7, and miR-125. Treatment with each hormone analog resulted in a change in BR expression.

Finally, I evaluated the effect of nutrients on expression levels. Surprisingly, though most transcripts were down-regulated during starvation, the expression of BR did not decrease, while microRNAs miR-34 and miR-14 were elevated. This may identify a novel role for miR-34 during starvation in an invertebrate, and raises the possibility that miR-34 and miR-14 are part of a starvation-induced stress response in the mosquito midgut.

In summary, this expression analysis suggests that microRNA regulation plays an important role during midgut metamorphosis, and reveals a new layer of regulatory complexity in the control of development in Ae. aegypti.

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