| Rapid growth, delicious meat, high survival rate and adaptability to cage culture conditions of the rice field eel stimulate one of the commercially important fish species in China. However, there are many problems on the sustainable development of the rice field eel. Firstly, the rice field eel with slow growth rate in the wild;Secondly, with the price of the fish meal was sustainable for growth, scale of farmed fish was threat by their costs; lastly, the technique of artificial propagation of the fish could not be solved in a short time, farmed fish mainly through the means to get to the wild fishing, induced degeneration of rice is declining. The myogenic regulatory factors(MRFs) was identify with a key factor in control the muscle development. In our research, we determined the expression of the MRFs with q PCR, and analyzed the morphometric of muscle fiber with frozen section technique. Characteristics of myogenin response to the muscle repair after injection injury. We explored the Effects of fish meal replacement by soy protein concentrate on growth, some serum biochemical index and growth-related genes expression in muscle for juvenile rice filed eel(Monopterus albus). Lastly, we evaluated the evolutionary relationship between the M. albus from four different areas. The main results were as follows.2、The MRFs were analyzed and the spatial-temporal specificity expression in the different developmental stages were determined. On the other hand, the fiber distribution pattern of different developmental stages was also characterized by frozen section with SDHase method. The MRFs played an important role in muscle growth and fiber distribution. This muscle consisted of round or polygonal muscle fibers separated by a fine septum of connective tissue, the endomysium. The diameter of white muscle fibers in our research was main distributed in 80-200 μm. There was a significant positive relationship between body mass, body length and mean fiber diameter. As ricefield eel increased in body size, mean muscle cell diameter proportionally increased from 34 ± 0.47 μm in the 5 g fish to 153 ± 7.25 μm in the114 g fish. The frequency distribution of < 20 μm diameter white muscle fiber in extra small group was significantly higher than in the other stages studied; Large group had a lower frequency of < 20 μm diameter fibers than the other stages. The frequency distribution of > 60 μm diameter fibers was significantly low in the extra small group and then increased through medium group and large group. The hyperplasia was observed as the fish attained larger sizes(114g)whereas the hypertrophy was observed in the previous developmental stage with the percent of fibers(< 40μm) decreased.3、It has long been known that taurine is beneficial for muscle repair process, but the molecular mechanisms involved are not completely elucidated. In our research,The MRFs expression was up-regulation both in the control and experimental group.However, with the help of taurine, the cross-section of skeletal muscle revealed a quickly and nicely to muscle repair with only 7 d, and the m RNA levels in the experimental group was also quickly downgrade in the 5 d. The result indicated that the taurine have some beneficial on the process of muscle repair.4、The present study revealed that up to 48% of fish meal protein can be replaced with SPC protein without causing reduction in growth. However,higher substitution levels induced negative influences on growth, digestive ability and protein metabolism and regulated the expression of muscle growth related genes.5、Four ricefield eel mitochondrial genomes from Guizhou province, Guangxi province, Hunan province and Guangdong province were cloned and deposited in the Gen Bank with accession number KP779622-KP779625, respectively. The mitochondrial genome were 16,622 bp in length and the organizations of the complete mitogenomes of the four ricefield eel similar to those of other teleost species. Each of the mitochondrial genome contained 13 protein-coding genes, 2 r RNA genes and 22 t RNA genes, as well as a putative control region(CR). Among the complete mitogenomes of the four ricefield eel analyzed, the G contents range from14.45%-14.58%. In additional,the obvious bias on A and C were demonstrated with AT-skew=0.03 and GC-skews=-0.34.In order to explicitly reveal the genetic diversity of ricefield eel from different areas, we analyzed the similarity and divergence of the four mitochondria ricefield eel.Furthermore, we analyzed the variable sites of the four ricefield eel. Among the 13protein-coding genes(excluding ND6), a total of 469 variable sites were identified in the four ricefield eel populations. The rate of point mutation between the four S.scherzeri was approximately 0.04%. Out of the 467 variable sites, 266 sites were located in the ND1-ND5 genes, 108 in the CO1-CO3 genes, 50 in the ATP6 and ATP8 genes, and the remaining 45 in the CYTB genes. In the 13 protein-coding genes, ND5 gene had the most variable sites(71), and ND6 had 30 variable sites. However, the highest rate of point mutation(1.2%)was obvious in ATP8 and the lowest in CO1. The variable sites and the sample length could have great influence on the different phylogeny performance. Thus, these results indicate that ND5 and ND4 were the best mt DNA markers to classify the different ricefield eel populations or subspecies. |
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