Expression Of MRFs And Muscle Growth During Starvation And Refeeding In Megalobrama Amblycephala

In fish’s life, due to living in an environment with a lot of uncertainties, changes in any of these factors are likely to make fish suffer from hunger or lack of nutritional stress. Fish will show the faster growth rate than in the fish which in a normal environment when environmental conditions with stress factors improve or disappear. That is named compensatory growth. Megalobrama amblycephala is a wild species that perched in the Lakes around middle and lower reaches of the Yangtze River, and widely adopted as the fine vegetarian fish species due to its low production cost, fast growth, delicious taste and high survival rate. However the culture of M. amblycephala groups has appeared germplasm degradation phenomenon in recent years. And some individuals appeared precocious puberty, miniaturization, disease breeding and quality decline of fish which associated with the change of breeding environment. A lot of researches have been conducted about effect of starvation and refeeding on morphology, physiology, biochemistry, enzyme activity of digestion and immunity. In order to explore the response mechanism of M. amblycephala for changes of nutrition environment from the molecular biology and genetics, we utilized starvation and refeeding experimental simulation to analyze the effects of starvation and refeeding on the phenotype of the experimental fish and expression of myogenic regulatory factors of M. amblycephala at the age of1year. The distribution structure of muscle fibers at the end of the test was also analyzed in our study. The results were shown below.No change was found for body length of fishes at the end of the test. The weight of group C (S14F14S14) fishes in starvation was significantly lower than the control group, while no significiant changes were found between the group B (S7F7> three cycles) and group D (S21F21), comparison with the control group. The result for condition factor and hepatosomatic index of M. amblycephala was shown below. Condition factor of experimental fishes showed a declining trend with the lasting time of starvation. Then it could rise to normal levels after a long enough time for feeding. Fishes first called of nutrients in the liver when they were suffered from hunger and first stored the energy in the liver as refeeding.The resulet for diameter of red and white muscle fibers suggested that starvation for M. amblycephala might lead to the miniaturization of muscle fibers, and the refeeding after starvation might promote the hypertrophy of skeletal muscle fibers. The starvation and refeeding might induce changes for the expression level of MRFs. Both the expression of Myf3and Myf6were positive correlation with the lasting time of starvation. However, starvation and refeeding have a significant impact on expression of Myf6. On the other hand, the expression ofMyf4and Myf5were both significantly lower than control group after21days of starvation. Moreover, starvation have a significant impact on expression of Myf4. Expression for four genes of MRFs were all highly relevant to the lasting time of starvation, and significant increased in group D which had7days of refeeding after21days of starvation. Then showed a declining trend with the lasting time of refeeding.