鸭发育早期骨骼肌TNNI1基因mRNA表达及与肌纤维生长的相关性分析

Expression profiles of the TNNI1 gene in the skeletal muscle and its correlation with the muscle fiber growth in early developmental ducks

为探讨慢收缩骨骼肌型Tnl(slow skeletal muscle troponin I,TNNI1)基因在鸭早期肌肉发育中的m RNA表达规律及与肌纤维发育的相关性,以地方品种高邮鸭为素材,采用实时荧光定量PCR方法,检测胚胎期21、25、27胚龄及出雏后5日龄时腿肌腓肠肌外侧头中TNNI1基因m RNA表达量,结果发现,25胚龄是TNNI1基因的表达高峰期,之后显著下调,并持续至5日龄。肌纤维类型变化则是随时间的推移,慢肌纤维比例逐渐升高,快白肌纤维比例逐渐下调;25胚龄时,慢肌纤维直径和横切面积均出现显著增高(P<0.05),快白肌纤维横切面积则出现下调;之后,3种类型肌纤维直径和横切面积在各个时间点之间无显著差异(P>0.05);相关性分析结果显示,TNNI1基因m RNA表达量与快红肌纤维比例呈显著负相关(P<0.05),与肌纤维直径、横切面积均无显著相关性(P>0.05)。提示TNNI1可能在鸭发育早期骨骼肌肌纤维类型转换中具有重要的作用。

In order to study the relationship between the expression of the slow skeletal muscle troponin I （TNNI1） gene and the growth of the muscle fiber in ducks at the early developmental stage, the mRNA of TNNI1 at embryonic day 21, 25, and 27 and the 5-day-old Gaoyou duck was quantified by RT-PCR in Lateral gastrocnemius muscle. As results, the highest level appeared at embryonic day 25, then significantly decreased to a very low level, and maintained this relative low level until the duck was 5-day-old. As time went on, the proportion of the slow muscle fiber increased gradually, while the fast white muscle fiber gradually decreased. The diameter and cross-sectional area of the slow muscle fiber significantly increased, while the fast white muscle fiber decreased at embryonic day 25. After that, there was no significant difference in the diameter and cross-sectional area among the three muscle fibers （P 〉 0.05）. The correlation analysis showed that the expression of TNNI1 was significantly negatively correlated with the ratio of the fast red muscle fiber and there was no significant correlation between TNNI1 expression and muscle fiber diameter and cross-sectional area （P 〉 0.05）. In conclusion, these results suggested that the TNNI1 gene might play an important role in transformation of skeletal muscle fiber type involved in the early growth of ducks..