By Ashlyn Rauch

Faculty Mentor: Dr. Ginny Morriss

Abstract

Activin β (Actβ) is a dimeric protein that regulates muscle growth and differentiation as part of the TGF-β superfamily of proteins. In humans, Actβ stimulates muscle atrophy; however, in the fruit fly, Drosophila melanogaster, Actβ can positively regulate muscle growth. The goal of this project was to drive CRISPR-mediated modulation of Actβ expression using the Drosophila Gal4/UAS system to assess the effects of Actβ modulation on the function and structure of skeletal muscles. Muscle function was assessed through climbing velocity and flight distance tests. A subset of flies from the analysis were frozen in preparation for cryogenic sectioning to assess muscle structure. Another subset of flies were prepared for isolation of RNA to confirm Actβ expression levels in the experimental groups, via reverse transcription quantitative polymerase chain reaction. Analysis of climbing velocity (cm/sec) was completed using Vernier Video Analysis software, showing there was a statistically significant in climbing velocity between the Actβ Knockout and Overexpression groups and between genders. Flight test assessed the flight distance (cm) of each fly using ImageJ image analysis software. There was no statistical difference between Actβ Knockout and Overexpression or between genders. The results of this study will be used as a baseline for comparison of muscle function in a fruit fly model of the muscle wasting disease myotonic dystrophy with or without modulated Activin β levels.