Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Animal and Nutritional Sciences

Committee Chair

Jianbo Yao.


As United States and world seafood demand increases, aquaculture production becomes more important. Limited knowledge of molecular regulation of muscle growth and flesh quality hinders genetic improvement of these important traits in fish. Our goal is to enhance muscle growth and fillet quantity in rainbow trout, Oncorhynchus mykiss. Muscle growth is determined primarily by rate of protein turnover. Unlike mammals, rapidly growing fish have reduced protein degradation rather than increased protein synthesis. Studies in mammals showed that muscle atrophy results from increased protein breakdown, and is associated with activation of the ubiquitin proteasome pathway including induction of the muscle-specific ubiquitin protein ligase, MuRF-1. Animals lacking MuRF-1 are resistant to muscle atrophy. In fish, little is known about the role of proteasome/MuRF pathway in muscle degradation. The objectives of this study were to: (1) clone and characterize MuRF genes in rainbow trout, and (2) determine expression of MuRF genes in association with starvation- and spawning-induced muscle atrophy in rainbow trout. We have identified full-length cDNA sequences for three MuRF genes (MuRF-1, MuRF-2, and MuRF-3). These genes encode proteins with typical MuRF structural domains, including a RING-finger, a B-box and a Leucine-rich coiled-coil domain. RT-PCR analysis showed that all three genes are predominantly expressed in muscle and heart tissues. Real time PCR analysis revealed that the expression of all MuRF genes is up-regulated in starvation- and spawning-induced muscle atrophy in rainbow trout. These results suggest an important role for the MuRF genes in fish muscle protein degradation. Further studies are warranted to assess the potential use of MURF genes as tools to monitor fish muscle growth and degradation.