Studies On Meat Quality And Related Candidate Genes Of Culter Alburnus In Xingkai Lake

Culter alburnus in Xingkai Lake, also known as Xingkai large white fish, the color of which is white as jade, and the meat quality is delicate and delicious, is one of China’s four major freshwater fish, and of high economic value. In recent years, due to overfishing and the deterioration of the environment of spawning grounds, wild Culter alburnus in Xingkai Lake has been increasingly endangering, when artificial breeding emerged as the times require. However, the one-sided pursuit of high growth rate, high yield brought the problem that the meat flavor of cultured population is in steep decline, lost in the taste of fresh and tender, which led the price far lower than the wild population and influenced its economic benefit seriously.In this study, in order to solve this problem, we use Culter alburnus in Xingkai Lake as the experimental object. Firstly, determine and compare Culter alburnus in Xingkai Lake of wild and cultured populations of different ages in muscle physical index (pH value, color and texture characteristics), characteristics of conventional nutritional index, amino acids, fatty acids, blood biochemical index and tissue in conventional analysis methods, and then make a preliminary assessment of the quality of muscle. Secondly, by using the method of Biochemistry and molecular biology and RACE and RT-PCR technology, clone the heavy chain myosin gene (MYHs), myogenic differentiation factor (MyoD), production of the obese gene (Leptin) and calpastatin (CAST) which are related to the meat quality, and then analyzes the structure and function of the gene. Adopting Real Time PCR, from the mRNA level of the gene in different age of wild and cultivated populations of expression, explore the relationship between gene expression and meat quality traits. From the molecular level, differences of the formation of muscle quality give preliminary explanation. The results are as follows:1. From2years old, the muscle pH of wild Culter alburnus in Xingkai Lake were significantly higher than cultured population (P<0.05), whose color were whiter, glittering and translucent, and its hardness, elasticity, recovery were also higher than cultured population (p<0.05), whose muscle taste better. The basic structure of muscle fiber of Culter alburnus in Xingkai Lake of wild and cultured populations are of the same, both in irregular polygon. However, the muscle fiber diameter of wild populations is smaller than cultured population, but its density is greater (p<0.05). This is explained in terms of features in muscle properties and organization of Culter alburnus in Xingkai Lake, wild meat is more excellent performance, so consumers’ desire to purchase is stronger. 2. There is no significant difference in nutrition o fmuscle from2instar of wild and cultured populations of Culter alburnus in Xingkai Lake(P>0.05); in age4and moisture6instar wild Culters Albumus muscle and crude protein content was significantly higher than cultured population(P<0.05), but the fat content was lower than cultured population (P<0.05). The calcium and phosphorus content of wild fish are higher than the common ones. The composition of amino acids in wild and farmed Culter alburnus in Xingkai Lake is the same, that is, glycine (Gly) was the highest, glutamate (Glu) and lysine (Lys) times. Total amino acid, essential amino acid contents of wild flavor of Culter alburnus in Xingkai Lake and umami total amino acid was higher than cultured population (P<0.05). Consequencely, the edible value and delicious meat of wild Culter alburnus in Xingkai Lake was significantly better than cultured population, with age more obvious.3. The composition of fatty acids of the wild and cultivated population of Culter alburnus in Xingkai Lake is the same, mainly with oleic acid (C18:1), linoleic acid (C18:2n6) and palmitic acid (C16:0). But the polyunsaturated fatty acid (PUFA), twenty C five acid (EPA) and twenty-two carbon six acid (DHA) was significantly higher than cultured population total (P<0.05). This is also one of main reasons why the meat flavor and nutritional function Culter alburnus in Xingkai Lake wild populations of is better than that of the cultured population. The cholesterol (TC) in serum, triglyceride (TG), blood glucose (Glu) content, total protein (TP) and albumin (ALB) in the wild population of Culter alburnus in Xingkai Lakewas significantly lower than cultured population, while the high density lipoprotein (HDLC)was higher than cultured population. Energy metabolism of wild Alice mouth Culter in Xingkai Lake is normal and blood lipid level is low, which reflects that the blood lipid and body fat is related, showing more excellent health level.4. Though the first time cloning isolated there were two subtypes of Culter alburnus in Xingkai Lake MYHs,(MYHa and MYHb), where MYHa cDNA was6003bp in length, open reading frame (ORF) is5802bp long, encoding1933amino acids; MYHb cDNA was5990bp, open reading frame of5793bp, encoding1930amino acids. They will be submitted to Genbank, the accession numbers of which are JX272926and JX402919. By comparison, the holomogy of the two gene homology is low (73%), and the3has the very big difference in ’untranslated regions. Therefore, this is the two isoforms of a gene.not only a structural protein but also a function of protein. MYHa and MYHb are respectively connected with the silver carp Hypophthalmichthys molitrix fast skeletal muscle MYH typel type and MYH type type3the highest homology with other fish, homology above90%, that of Culter alburnus in Xingkai Lake MYHs is more conservative.5. From the first isolation of Culter alburnus in Xingkai Lake, the MyoD gene’s full-length cDNA was of1096bp, an open reading frame of828bp, encoding275amino acids. Submit it to Genbank, and the accession number was KC782835. Through the analysis of its structure, the amino acid had the typical domains of bHLH with the family, in which1-84amino acids alkaline region, ninety-eighth-141amino acids for the helix-loop-helix (HLH) structure. Culter alburnus in Xingkai Lake and grass carp MyoD’ shomology is the highest, up to99.3%. Compared with mammals, there is also more than60%homologous, description of Culter alburnus in Xingkai Lake MyoD quite conservative.6. The obesity gene product from the first isolation of Culter alburnus in Xingkai Lake is Leptin, whose cDNA was1208BP in length, open reading frame of522bp, encoding173amino acids. Submitted it to Genbank, and the accession number is KC782835. Analysis shows that the culter leptin N end20-21for restriction enzyme sites, forming a signal peptide.7. There are totally1997bp from the first clone isolated from a partial sequence of Culter alburnus in Xingkai Lake CAST. Through the NCBI online Blast analysis software comparison, it is found that the sequences with the published zebrafish and grass carp CAST similarity were90%and83%, indicating that CAST gene is relatively conservative.8. Having made the research of expression of different periods of wild and cultivated population of Culter alburnus in Xingkai Lake muscle tissue MYHs, MyoD, Leptin and CAST gene, The research showed that from age2to age6, the expression of wild populations of MYHa was significantly lower than cultured population (P<0.05), while MYHb was significantly higher than cultured population, for it is related with the size of fish. The two effect the characters of meat at the same time. The up-regulated from MyoD gene expression after2years of age, Leptin genes showed down regulation of expression of CAST gene, and a downward trend from age4began to clear. MYHs and MyoD is a major gene controlling muscle development, Leptin gene and body fat metabolism, the only major gene speculated that CAST gene did not affect the meat tenderness formation, is more likely to participate in the regulation of muscle tenderness together with other genes of calpain system.