Data_Sheet_3_Comparison of muscle metabolomics between two Chinese horse breeds.CSV

With their enormous muscle mass and athletic ability, horses are well-positioned as model organisms for understanding muscle metabolism. There are two different types of horse breeds—Guanzhong (GZ) horses, an athletic breed with a larger body height (~148.7 cm), and the Ningqiang pony (NQ) horses, a lower height breed generally used for ornamental purposes—both inhabited in the same region of China with obvious differences in muscle content. The main objective of this study was to evaluate the breed-specific mechanisms controlling muscle metabolism. In this study, we observed muscle glycogen, enzyme activities, and LC–MS/MS untargeted metabolomics in the gluteus medius muscle of six, each of GZ and NQ horses, to explore differentiated metabolites that are related to the development of two muscles. As expected, the glycogen content, citrate synthase, and hexokinase activity of muscle were significantly higher in GZ horses. To alleviate the false positive rate, we used both MS1 and MS2 ions for metabolite classification and differential analysis. As a result, a total of 51,535 MS1 and 541 MS2 metabolites were identified, and these metabolites can separate these two groups from each other. Notably, 40% of these metabolites were clustered into lipids and lipid-like molecules. Furthermore, 13 significant metabolites were differentially detected between GZ and NQ horses (fold change [FC] value ≥ 2, variable important in projection value ≥1, and Q value ≤ 0.05). They are primarily clustered into glutathione metabolism (GSH, p = 0.01), taurine, and hypotaurine metabolism (p < 0.05) pathways. Seven of the 13 metabolites were also found in thoroughbred racing horses, suggesting that metabolites related to antioxidants, amino acids, and lipids played a key role in the development of skeleton muscle in horses. Those metabolites related to muscle development shed a light on racing horses' routine maintenance and improvement of athletic performance.

马拥有庞大的肌肉量与卓越的运动能力，是探究肌肉代谢机制的理想模式生物（model organism）。本研究涉及两个不同的马品种：一是关中马（Guanzhong, GZ），属于运动型品种，体高约148.7厘米；二是宁强矮马（Ningqiang pony, NQ），为体型较矮的品种，多用于观赏用途。二者均栖息于中国同一区域，但肌肉含量存在显著差异。本研究的核心目标为解析调控肌肉代谢的品种特异性机制。本研究分别采集6头关中马与6头宁强矮马的臀中肌样本，检测其肌糖原含量、酶活性，并采用液相色谱-串联质谱非靶向代谢组学（LC–MS/MS untargeted metabolomics）技术进行分析，以探寻与两种马肌肉发育相关的差异代谢物。正如预期，关中马的肌糖原含量、柠檬酸合酶（citrate synthase）与己糖激酶（hexokinase）活性均显著高于宁强矮马。为降低假阳性率，本研究同时利用MS1与MS2离子进行代谢物分类与差异分析。结果共鉴定出51535个MS1代谢物与541个MS2代谢物，且这些代谢物可有效区分两个马品种群体。值得注意的是，其中40%的代谢物归属于脂类及脂类样分子家族。此外，共筛选得到13个差异显著的代谢物（倍数变化（fold change, FC）≥2，投影变量重要性（variable important in projection, VIP）≥1，Q值≤0.05）。这些差异代谢物主要富集于谷胱甘肽代谢（glutathione metabolism, GSH, p=0.01）、牛磺酸与亚牛磺酸代谢（taurine and hypotaurine metabolism, p<0.05）通路。13个差异代谢物中有7个也在纯血赛马（thoroughbred racing horses）中被检出，这表明与抗氧化剂、氨基酸及脂类相关的代谢物在马骨骼肌发育过程中发挥关键作用。上述与肌肉发育相关的代谢物可为赛马的日常养护及运动能力提升提供理论依据。