The myofibrillar fragmentation index (MFI) is an indicative trait for meat tenderness. Longissimus thoracis muscle samples from the 20 most extreme bulls (out of 80 bulls set) for MFI (high (n = 10) and low (n = 10) groups) trait were used to perform transcriptomic analysis, using RNA Sequencing (RNA-Seq). An average of 24.616 genes was expressed in the Nellore muscle transcriptome analysis. A total of 96 genes were differentially expressed (p value ≤ 0.001) between the two groups of divergent bulls for MFI. The HEBP2 and BDH1 genes were overexpressed in animals with high MFI. The MYBPH and MYL6, myosin encoders, were identified. The differentially expressed genes were related to increase mitochondria efficiency, especially in cells under oxidative stress conditions, and these also were related to zinc and calcium binding, membrane transport, and muscle constituent proteins, such as actin and myosin. Most of those genes were involved in metabolic pathways of oxidation-reduction, transport of lactate in the plasma membrane, and muscle contraction. This is the first study applying MFI phenotypes in transcriptomic studies to identify and understand differentially expressed genes for beef tenderness. These results suggest that differences detected in gene expression between high and low MFI animals are related to reactive mechanisms and structural components of oxidative fibers under the condition of cellular stress. Some genes may be selected as positional candidate genes to beef tenderness, MYL6, MYBPH, TRIM63, TRIM55, TRIOBP, and CHRNG genes. The use of MFI phenotypes could enhance results of meat tenderness studies.

中文翻译：

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使用基因表达谱来鉴定与肌原纤维断裂指数性状潜在相关的转录本。

肌原纤维断裂指数（MFI）是肉嫩的指示性状。 使用RNA测序（RNA-Seq ），从MFI（高（n  = 10）和低（n = 10）组）的20只最极端公牛（每组80只公牛）中提取出的最长肌胸肌样本用于转录组分析）。Nellore肌肉转录组分析平均表达了24.616个基因。两组不同的MFI公牛之间共有96个基因差异表达（p值≤0.001）。该HEBP2和BDH1基因在动物体内具有高MFI过表达。该MYBPH和MYL6，肌球蛋白编码器，已确定。差异表达的基因与增加线粒体效率有关，尤其是在氧化应激条件下的细胞中，并且还与锌和钙的结合，膜转运以及肌动蛋白和肌球蛋白等肌肉组成蛋白有关。这些基因中的大多数都参与了氧化还原，质膜中乳酸的运输和肌肉收缩的代谢途径。这是第一项在转录组学研究中应用MFI表型来鉴定和理解差异表达基因的牛肉嫩度的研究。这些结果表明，在细胞应激条件下，高和低MFI动物之间基因表达的差异与氧化纤维的反应机制和结构成分有关。MYL6，MYBPH，TRIM63，TRIM55，TRIOBP和CHRNG基因。MFI表型的使用可以增强肉嫩度研究的结果。