|Rawles, Steven - Steve|
|GAYLORD, THOMAS - Us Fish And Wildlife Service|
|McEntire, Matthew - Matt|
Submitted to: Aquaculture Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2015
Publication Date: 4/13/2015
Citation: Childress, C.J., Fuller, S.A., Rawles, S.D., Beck, B.H., Gaylord, T.G., Barrows, F., Mcentire, M.E. 2015. Lysine supplementation of commercial fishmeal-free diet in hybrid striped bass Morone chrysops x M. saxatilis affects expression of growth related genes. Aquaculture Nutrition. 22:738-744.
Interpretive Summary: When fishmeal in fish feed is replaced with different proteins, fish performance is often poor due to imbalances in essential nutrients in the resulting feed. Our previous study showed that hybrid striped bass muscle appears to be a reasonable pattern of essential amino acid ratios and levels to target for fishmeal-free diets for this fish. In the current study we wanted to see how changing the amount of the nutrient lysine would affect how two different muscle genes would be expressed in hybrid striped bass. These two genes (along with many others) are responsible for signaling the muscle when it should start or stop growing. Our data showed that changing the amount of the amino acid lysine in the diet of hybrid striped bass significantly changed the amount of myogenin, the gene responsible for signaling muscle to start growing, found in the fish’s muscle, but did not significantly alter the amount of myostatin, the gene responsible for signaling muscle to stop growing. Also, the ratio of these two genes was affected by which diet they were fed, which was also similar to the growth data we saw in our previous studies. Together, this information may be a useful marker for selecting for improved growth performance.
Technical Abstract: Our recent results in hybrid striped bass (HSB) concluded that ideal protein theory accurately predicts first-limiting amino acids in commercial diet formulations if accurate amino acid availability data are used and that appropriate levels of supplemental lysine are needed in order to improve fish performance from fishmeal-free diets. Our goal in the current study was to elucidate how dietary lysine supplementation of a commercial fishmeal-free diet influences the expression of two genes, myostatin and myogenin controlling myogenesis in differentially growing groups of HSB. Real time RT-PCR results in HSB suggest that the levels of lysine added to the diet (1.78, 3.51, 5.10 g/100g of diet) has an impact on myogenin relative to the basal unsupplemented diet, but no effect on myostatin. Moreover, our data further suggest that the amount of dietary lysine supplementation influenced the ratio of myostatin/myogenin expression in HSB, and that this pattern mimicked that of most of the growth, composition of growth and nutrient retention data from our previous study, and may therefore be a useful marker for selecting fish for improved growth performance.