Expression Patterns And Genetic Variation Of PYGM Gene In Chinese Qinchuan Cattle

PYGM gene encodes muscle glycogen phosphorylase which is one of important enzymes in glycogen metabolism of organism. It can degrade glycogen into glucose-6-phosphate and then convert into glucose which is the main energy resource during degradation of glycogen. PYGM gene is essential for growth, development and health. In this trial, we selected PYGM and study its function in Qinchuan cattle. First, we analyzed the stracture and function of PYGM by bioinformatics tools, studied the expression patterns of PYGM in6tissues of Qinchuan adult individuals and embryos and then analyzed the correlationship of PYGM polymorphism and growth and carcass traits of Qinchuan cattle by using DNA sequencing and PCR-RFLP technologies. Main results as below:1. Results of bioinformatics analyze of PYGM and tissue expression patternsAs the results showed, length of PYGM encoding area is2529bp, encoding842amino acids. The formula of protein is C4375H6818N1204O1251S31, molecular weight97.29kD, isoelectric point6.65, instability index37.31, aliphatic index87.90, grand average of hydropathicity-0.380. Some regions of the protein have strong hydrophobicity and PYGM gene of cattle has a relatively strong transmembrane helix which located at140-158amino acids.27possible protein kinase phosphorylation sites exist in the protein, which is coordinate with the functional stracture of glycogen phosphorylase. Besides, two low complexity structure domain locate in121-128and130-142amino acids and the result is coordinate with the prediction of transmembrane protein structure as before.The expression levels of PYGM in adult individuals and embryos tissues (lung, heart, tongue, liver, spleen and longissimus dorsi) of Qinchuan cattle are all relatively high. The expression level in adult individuals heart muscle is highest and in embryos spleen tissue is lowest. Overall, the expression levels in heart, tongue, liver and longissimus dorsi are higher than that in lung and spleen both in adult individuals and embryos. The data shows higher in adult individuals than embryos. It demonstrates that as an indispensable gene of regulation of glycogen metabolism, PYGM expresses relatively high at the beginning of organism especially in muscle tissue where needs more energy.2. The correlationship of PYGM polymorphism and growth and carcass traits in Qinchuan cattleIt is the first time to study polymorphism of PYGM in Qinchuan cattle using DNA sequencing and PCR-RFLP and we detected two SNPs in PYGM. As the results showed, individuals with BB and DD genotypes have significant negative effect on body weight and carcass weight (P<0.05). Their performance is not as good as other genotypes. So it shows that allele A and C may have positive effect on body weight and carcass weight of Qinchuan cattle.Allele A and C are domain dominant alleles. Individuals contain allele A and C take part more than90%of the population. So during breeding, genotypes contain allele A and C should be selected. As mentioned above, the two mutations locate in intron1and intron6of PYGM have significant effect on some characters of Qinchuan cattle. It concludes that the two mutations of PYGM can be used as molecular makers in Qinchuan cattle breeding programme.