Martins Taiane S, Sanglard Letícia M P, Silva Walmir, Chizzotti Mário L, Rennó Luciana N, Serão Nick V L, Silva Fabyano F, Guimarães Simone E F, Ladeira Márcio M, Dodson Michael V, Du Min, Duarte Marcio S
Department of Animal Science, Universidade Federal de Viçosa, Viçosa, Brazil.
Department of Animal Science, Universidade Federal de Viçosa, Viçosa, Brazil; Animal Biotechnology Laboratory-LABTEC, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
PLoS One. 2015 Oct 5;10(10):e0139943. doi: 10.1371/journal.pone.0139943. eCollection 2015.
Studies have shown that intramuscular adipogenesis and fibrogenesis may concomitantly occur in skeletal muscle of beef cattle. Thus, we hypothesized that the discrepancy of intramuscular fat content in beef from Nellore and Angus was associated with differences in intramuscular adipogenesis and fibrogenesis during the finishing phase. To test our hypothesis, longissimus muscle samples of Nellore (n = 6; BW = 372.5 ± 37.3 kg) and Angus (n = 6; BW = 382.8 ± 23.9 kg) cattle were collected for analysis of gene and protein expression, and quantification of intramuscular fat and collagen. Least-squares means were estimated for the effect of Breed and differences were considered at P ≤ 0.05. A greater intramuscular fat content was observed in skeletal muscle of Angus compared to Nellore cattle (P≤0.05). No differences were observed for mRNA expression of lipogenic and lipolytic markers ACC, FAS, FABP4, SERBP-1, CPT-2, LPL, and ACOX (P > 0.05) in skeletal muscle of Nellore and Angus cattle. Similarly, no differences were observed in mRNA expression of adipogenic markers Zfp423, PPARγ, and C/EBPα (P>0.05) However, a greater PPARγ protein content was observed in skeletal muscle of Angus compared to Nellore cattle (P≤0.05). A greater abundance of adipo/fibrogenic cells, evaluated by the PDGFRα content, was observed in skeletal muscle of Angus than Nellore cattle (P≤0.05). No differences in fibrogenesis were observed in skeletal muscle of Angus and Nellore cattle, which is in accordance with the lack of differences in intramuscular collagen content in beef from both breeds (P>0.05). These findings demonstrate that difference in intramuscular fat content is associated with a slightly enhanced adipogenesis in skeletal muscle of Angus compared to Nellore cattle, while no difference in fibrogenesis.
研究表明，肉牛骨骼肌中可能同时发生肌内脂肪生成和纤维生成。因此，我们推测内洛尔牛和安格斯牛牛肉中肌内脂肪含量的差异与育肥阶段肌内脂肪生成和纤维生成的差异有关。为了验证我们的假设，采集了内洛尔牛（n = 6；体重 = 372.5 ± 37.3千克）和安格斯牛（n = 6；体重 = 382.8 ± 23.9千克）的背最长肌样本，用于分析基因和蛋白质表达，并对肌内脂肪和胶原蛋白进行定量分析。估计了品种效应的最小二乘均值，并在P≤0.05时考虑差异。与内洛尔牛相比，安格斯牛骨骼肌中的肌内脂肪含量更高（P≤0.05）。在内洛尔牛和安格斯牛的骨骼肌中，脂肪生成和脂肪分解标志物ACC、FAS、FABP4、SERBP-1、CPT-2、LPL和ACOX的mRNA表达没有差异（P > 0.05）。同样，脂肪生成标志物Zfp423、PPARγ和C/EBPα的mRNA表达也没有差异（P>0.05）。然而，与内洛尔牛相比，安格斯牛骨骼肌中的PPARγ蛋白含量更高（P≤0.05）。通过PDGFRα含量评估，安格斯牛骨骼肌中的脂肪/纤维生成细胞丰度高于内洛尔牛（P≤0.05）。在安格斯牛和内洛尔牛的骨骼肌中未观察到纤维生成的差异，这与两个品种牛肉中肌内胶原蛋白含量缺乏差异一致（P>0.05）。这些发现表明，与内洛尔牛相比，安格斯牛骨骼肌中肌内脂肪含量的差异与脂肪生成略有增强有关，而纤维生成没有差异。
