Transcriptomic investigation of embryonic pectoral muscle reveals increased myogenic processes in Shitou geese compared to Wuzong geese

1.Embryonic stages before birth are crucial for poultry muscle development, as this determines muscle mass in adulthood. This study characterised the distinction in embryonic pectoral muscle development between Wuzong (WZE, small) and Shitou (STE, large) geese (two indigenous goose breeds in Guangdong Province, China) at embryonic days 15 (E15), 23 (E23) and the day of hatching (P1) to gain insights into the regulatory mechanisms of muscle development. 2.The results showed that STE had significantly higher myofibre density during E15-P1 and had significantly larger myofibre diameter at E15 than WZE. By RNA-sequencing analysis, 19 507 genes were detected, and 7121 differentially expressed genes (DEGs) were identified. 3.Gene expression distinctions between breeds began increasing from E23, and WZE had different gene expression profiles compared to STE. A GO analysis of DEGs indicated that myo-genes involved at E15 may influence distinct pectoral muscle development characteristics between WZE and STE. The RT-qPCR results were consistent with the RNA-sequencing analysis. Four muscle structure protein coding genes (MYL2, MYL3, TNNI2 and TNNC2 and three other functional genes (CAV3, CACNA1S and NOS1) were identified in a predicted interaction network. These functional genes may interact with muscle structural protein coding genes to regulate embryonic pectoral muscle development in WZE and STE geese. 4.The study revealed that STE and WZE had divergent embryonic pectoral muscle development patterns and these differences may begin before E15.

1. 家禽出生前的胚胎阶段对肌肉发育至关重要，该阶段直接决定成年个体的肌肉重量。本研究针对中国广东省两个地方鹅品种——乌鬃鹅（WZE，小型）和石砣鹅（STE，大型），在胚胎发育第15天（E15）、第23天（E23）以及出雏日（P1）三个时间点，解析二者胚胎期胸肌发育的差异，以深入探究肌肉发育的调控机制。2. 结果显示，在E15至P1阶段，STE的肌纤维密度显著高于WZE，且在E15时STE的肌纤维直径显著大于WZE。通过RNA测序（RNA-sequencing）分析，共检测到19507个基因，鉴定出7121个差异表达基因（DEGs）。3. 品种间的基因表达差异自E23起逐渐增大，WZE与STE的基因表达谱存在显著差异。对DEGs进行基因本体（Gene Ontology, GO）分析后发现，E15时期的肌源性基因可能是导致两个鹅品种胸肌发育特征差异的关键因素。实时定量聚合酶链反应（RT-qPCR）结果与RNA测序分析结果一致。在预测的蛋白互作网络中，共鉴定出4个肌肉结构蛋白编码基因（MYL2、MYL3、TNNI2和TNNC2）以及3个功能基因（CAV3、CACNA1S和NOS1），这些功能基因可能与肌肉结构蛋白编码基因相互作用，共同调控乌鬃鹅与石砣鹅的胚胎期胸肌发育。4. 本研究揭示，乌鬃鹅与石砣鹅的胚胎期胸肌发育模式存在显著分化，且二者的发育差异可能早在E15之前便已启动。