Characterization Of Duck Pax3/7and Its Expression Patterns

The Pax3and Pax7gene play pivotal roles in muscle development and regulating cell differentiation, renewing and apoptosis during embryonic muscle myogenesis. Pax3and Pax7were found to have overlap functions and compensations.Previous researches about Pax3were mainly focus on the early embryo-myogenesis and fewer reports in post-natal myogenesis and within the Pax7were mainly in post-natal myogenesis.However, limited knowleghge about expression patterns of Pax3and Pax7, and wether they had lovrlap functions or still reguating Myf5and MyoD have been made involed in waterfowl embryonic and postanatal stages. In this study, we employed Peking duck as materials to clone the mRNA sequence of Pax3and Pax7, and to analyze the tissue-specific expression profiles on Pax3, Pax7and MyoD genes. The developing expression profiles on Pax3, Pax7, Myf5and MyoD genes were analyzed as following. Forskolin, repressing Pax3expression, was added in cultured duck myoblast, then the expression levels of Pax7, Myf5and MyoD were analyzed. The main results are as follows:1. We cloned Pax3and Pax7mRNA of Peking duck by RACE assays. The Pax3/7coding domain sequences (CDS) contain1,449bp and1,512bp, and encoding482and503amino acids, respectively. The Pax3and Pax7showed high conservation between species.2. Bioinformatics analysis showed that the Pax3and Pax7protein sequences of Peking duck have conserved domains, which are called Paired Box Domain, Homeobox domain and Paired box protein7family Domain. The Domains were conserved between species. Secondary structure prediction showed that there were several types of modification sites both in duck Pax3and Pax7.3. The qRT-PCR assay was performed to analysis the expression profiles in30d Peking duck with13tissues and found that the Pax3, Pax7and MyoD has different expression profiles between tissues and sex (p<0.05). In13tissues, the expression level of Pax7was significantly higher than Pax3(p<0.05). There have correlation between Pax3, Pax7and MyoD in breast muscle, heart, spleen and brain (p<0.05).4. The developmental expression patterns of Pax3, Pax7, Myf5and MyoD within Peking duck breast muscle and leg muscle during embryonic and post-natal development were analyzed by qRT-PCR. Pax3showed similar expression patterns between breast muscle and leg muscle during embryo and post-natal muscle development, however, Pax7showed the significantly different expression patents. Myf5and MyoD showed the different expression patterns during embryonic muscle development, but they had similar expression patterns with Pax3and Pax7in particular times. After birth, there have similar expression patterns between breast muslce and leg muscle both in male and female ducks, but the change rang were differently.5. Forskolin, repressing Pax3expression, was added in cultured duck myoblast. During cell proliferation, the expression levels of Pax3and Pax7were both down regulated, and the expression peak of Myf5and MyoD were both delayed, suggesting that Pax3and Pax7showed positive regulation on Myf5and MyoD in duck myoblast.