鸭发育早期骨骼肌异步发育和IGF-I/MSTN-A mRNA表达的相关性

【目的】选择生长速度不同的高邮鸭和金定鸭为试验模型,比较2个不同品种鸭胚胎期和出雏早期骨骼肌中胰岛素样生长因子I(insulin-like growth factor I,IGF-I)、肌肉生长抑素A(myostatin A,MSTN-A)mRNA的表达规律及其与胸浅肌和腓肠肌(简称为胸腿肌)发育模式的相关性。【方法】在鸭13、17、21、25、27胚龄和出雏后7日龄时,记录体重、胸浅肌(PM)和腓肠肌外侧头(LM)的重量,采用实时荧光定量PCR方法研究骨骼肌中IGF-I和MSTN mRNA的表达规律。【结果】本试验证明鸭早期发育过程中,体重和骨骼肌重的变化呈现极显著的品种和时间特异性;鸭胚胎期胸/腿肌的IGF-I和MSTN-A mRNA的表达与体重、胸/腿肌重均呈极显著的负相关,各自与胸/腿体指数则呈反式的相关性(正/负),均在13胚龄有一个表达高峰,IGF-I和MSTN-A mRNA表达之间存在极显著的正相关;鸭PM中IGF-I mRNA表达转折点的出现时间与胸肌绝对生长和相对生长变化趋势是吻合的,而LM中IGF-I mRNA的表达与腿肌生长和肌纤维特性变化均不相符;鸭胚胎期MSTN-A mRNA的表达趋势与骨骼肌生长和肌纤维数量形成高峰同步;胸腿肌中IGF-I/MSTN-A mRNA表达比值的变化趋势和肌纤维特性变化吻合,PM中的IGF-I/MSTN-A mRNA表达比值的差异点和PM重量出现品种差异的时间点一致。【结论】在胚胎发育中后期和出雏后早期,鸭的胸腿肌呈现异步发育模式,骨骼肌中IGF-I和MSTN mRNA表达的相对水平参与骨骼肌生长速率的调节。

Correlation of the Relative Levels of Insulin-Like Growth Factor - I and Myostatin mRNA Expression and Asynchronous Development of Skeletal Muscles Development in Ducks During Early Development

【Objective】 The present experiment was conducted to study the mRNA expression characterization of insulin-like growth factor 1 (IGF-I) and myostatin A (MSTN-A), thedevelopmental pattern in duck skeletal muscles and their correlation during embryogenesis and post-hatching development in different breeds of ducks. 【Method】We have compared the ontogeny of body weight, the weight of pectoralis major (PM) and lateral gastrocnemius muscle (LM) and the mRNA expression of insulin-like growth factor-I (IGF-I) and myostatin A (MSTN-A) at the embryonic days 13, 17, 21, 25, 27 and the neonatal age of 7 days of Gaoyou duck and Jinding duck. 【Result】During embryogenesis and post-hatching development, the weight of PM and LM showed an extreme significant difference by duck variety and time. The mRNA expression of IGF-I and MSTN-A in duck breast/leg muscles had significantly negative correlations with body weight and weight of skeletal muscle, but had a positive correlation with breast/leg muscles index. During early development, there were extremely significant positive correlations between the mRNA expression of IGF-I and MSTN-A, and there were peaks in the mRNA expression of IGF-I and MSTN-A at embryonic age of 13 days. The turning points of IGF-I mRNA expression in duck PM were matched with PM growth, and but not for LM. During duck myogenesis, the profile of MSTN-A expression showed synchronization with growth of skeletal muscle and the peaks of proliferation in changes of myofiber characters, and the differences of the IGF-I/MSTN-A mRNA ratio in PM between the two myoblasts. The IGF-I/MSTN-A mRNA ratio in PM and LM were significantly higher with a similar trend in the breeds matched the timing of varieties difference in PM weight. 【Conclusion】 During embryogenesis and post-hatching development, the duck PM and LM developed in an asynchronous pattern. The relative levels of IGF-I and MSTN mRNA may participate to set muscle growth rate along development.