Submitted to: Marine Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 9, 2005
Publication Date: July 1, 2005
Citation: Oveturf, K.E. and Johansen, K. 2005. Quantitative expression analysis of genes affecting muscle growth during the development of rainbow trout (oncorhynchus mykiss). Marine Biology. Interpretive Summary: Manuscript Title- Real-time quantitative expression analysis of genes affecting muscle growth during the development of rainbow trout (Oncorhychus mykiss) The aquaculture industry is dependent on the production of fish with high quality muscle. We used rainbow trout as a model of commercially important fish species to analyze the molecular control of muscle growth. Two families of transcription factors, the MRFs and the MEFs, and a family of secreted proteins, the Myostatins, are the main regulators of muscle growth in vertebrates. To test the mRNA expression levels of the genes that encode these proteins, we used real-time RT-PCR, a technique that quantitates the number of specific mRNA copies present in a selected tissue. We tested expression in the white muscle at nine stages of rainbow trout development, then used the expression data and the known function of each gene to determine the extent of hyperplasia (cell proliferation resulting in the generation of new muscle tubes), hypertrophy (increase in muscle tube size), and restriction of muscle growth occurring at each developmental stage. These results should provide valuable information for aquaculturists.
Technical Abstract: Manuscript Title- Quantitative expression analysis of genes affecting muscle growth during the development of rainbow trout (Oncorhynchus mykiss) The molecular characterization of the hyperplasia and hypertrophy that characterize post-embryonic muscle development in the rainbow trout is of great interest to aquaculturists because of the commercial value of the species. Determination of temporal expression levels of the genes that control muscle development is an important step in molecular analysis. Real-time quantitative RT-PCR was used to characterize expression in the muscle of three MRFs, two MEFs, and two myostatins during nine stages of trout development. Expression of genes that promote muscle growth (MRFs and MEFs) peaked in swim-up fry, and in some cases again in 25g, 140g, and spawning fish. Genes that restrict muscle growth (myostatins) were expressed at very low levels early in development, but when tested in 140g and spawning fish, expression levels were elevated. Expression levels and the known function of each tested gene were used to infer the extent of hyperplasia, hypertrophy, and restriction of muscle growth during each stage. Both hyperplasia and hypertrophy appeared to peak in swim-up fry and spawning females, and hyperplasia also appeared to peak in 25g fish. These results should provide valuable information for developmental biologists and those interested in understanding muscle growth in fish.