调节鸡肌纤维类型特异性和维持性的机制还很不清楚。在哺乳动物中，CSRP3在维持典型的肌肉结构和功能方面起着非常重要的作用。本研究探讨了CSRP3在鸡骨骼肌中的作用。首先，制备了鸡CSRP3抗体，比较了四种不同肌纤维组成的鸡骨骼肌中CSRP3基因的mRNA和蛋白表达水平。然后分析CSRP3沉默后对鸡成肌细胞转录组表达谱的影响。结果表明，鸡骨骼肌中CSRP3基因的mRNA和蛋白表达水平均与其肌纤维类型组成相关。以Q<0.05，差异倍数大于1.5为筛选条件，共鉴定出650个差异基因。CSRP3沉默后，255个基因表达上调，395个基因表达下调。功能富集分析结果表明，心肌细胞肾上腺素能信号、脂肪细胞因子信号和apelin信号等多种通路在差异表达基因和所有表达基因中均显著（P<0.05）富集。共表达基因网络结果表明，CSRP3沉默后引起与肌原纤维组装、肌肉分化和收缩相关基因的代偿性上调（Q<0.05）。同时，CSRP3沉默后，两个快速肌球蛋白重链基因（MyH1B和MyH1E）表达上调（Q<0.05）。这些结果表明，CSRP3在鸡肌纤维组成中发挥着重要作用，并可能通过调节MyH1B和MyH1E的表达从而影响鸡肌纤维类型的分布。

Little is known about the muscle developmental patterns during embryonic to neonatal development in ducks. We investigated the developmental patterns in the lateral gastrocnemius muscles of Gaoyou and Jinding ducks differing in their muscle growth rates during the final stages of egg incubation and the first week after hatching. Expression of the MyoD gene was quantified by quantitative real-time PCR (qRT-PCR). The average cross-sectional area and diameter of the fibers increased from embryonic day 21 (E21), peaking at E27, and then declining slightly 7 d after hatching. The density of the fibers decreased initially but increased after hatching in both breeds and sexes. The within-breed variation in muscle fiber-type composition was greater than the average variation between the breeds. Overall, the percentage of type I fibers increased and that of type IIb fibers decreased consistently. However, the percentage of type IIa fibers was almost constant as development proceeded in both duck breeds. The profiles of MyoD mRNA expression were similar in both breeds, and a significantly positive relationship was observed between the expression of MyoD and the percentage of type IIb fibers. This study firstly revealed the characteristics of duck muscle development and differences between the two breeds differing in growth rates. Moreover, type IIb fibers might convert to type I fibers in the lateral gastrocnemius, while MyoD may potentially function in controlling the muscle fiber phenotype during the secondary myogenesis of muscle development.

  Calcineurin (Cn or CaN) is implicated in the control of skeletal muscle fiber phenotype and hypertrophy. However, little information is available concerning the expression of Cn in chickens. In the present study, the expression of two Cn subunit genes (CnAα and CnB1) was quantified by qPCR in the lateral gastrocnemius (LG, mainly composing of red fast-twitch myofibers), the soleus (mainly composing of red slow-twitch myofibers) and the extensor digitorum longus (EDL, mainly composing of white fast-twitch myofibers) from Qingyuan partridge chickens (QY, slow-growing chicken breed) and Recessive White chickens (RW, fast-growing chicken breed) on different days (1, 8, 22, 36, 50 and 64 days post-hatching). Although CnAα and CnB1 gene expressions were variable with different trends in different skeletal muscles in the two chicken breeds during postnatal growth, it is highly muscle phenotype and breed specific. In general, the levels of CnAα and CnB1 gene expressions of the soleus were lower than those of EDL and LG in both chicken breeds at the same stages. Compared between the two chicken breeds, the levels of CnAα gene expression of the three skeletal muscles in QY chickens were higher than those in RW chickens on days 1 and 22. However, on day 64, the levels of both CnAα and CnB1 gene expressions of the three skeletal muscles were lower in QY chickens than those in RW chickens. Correlation analysis of the levels of CnAα and CnB1 gene expressions of the same skeletal muscle showed that there were positive correlations for all three skeletal muscle tissues in two chicken breeds. These results provide some valuable clues to understand the role of Cn in the development of chicken skeletal muscles, with a function that may be related to meat quality.