Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.
J Anim Sci. 2012 Aug;90(8):2505-14. doi: 10.2527/jas.2011-4602. Epub 2012 Feb 3.
We have demonstrated that among carcass adipose tissue depots, brisket subcutaneous adipose tissue contains the greatest concentration of MUFA and lowest concentration of SFA. Therefore, we hypothesized that brisket subcutaneous adipose tissue depots would exhibit greater adipogenic gene expression over time than other major subcutaneous adipose tissue depots. Four Angus steers, each at 9, 12, 14, and 16 mo of age, were harvested and fresh subcutaneous adipose tissue samples were collected from over the brisket, chuck, rib, loin, sirloin, round, flank, and plate. Relative gene expression for C/EBPβ, PPARγ, carnitine palmitoyltransferase-1 beta (CPT-1β), stearoyl-coenzyme A desaturase (SCD), AMP-activated protein kinase alpha (AMPKα), and G-coupled protein receptor 43 (GPR43) was analyzed by quantitative real-time PCR. Expression of C/EBPβ, PPARγ, and CPT-1β was greatest at 12 to 14 mo of age (all P < 0.0001) and declined to very low abundance by 16 mo of age in all depots. Expression of PPARγ and CPT-1β was greater (P < 0.03) in flank, rib, and sirloin subcutaneous adipose tissues than in brisket and round adipose tissues. The expression of the SCD gene did not differ among the 4 age groups (P = 0.95). The palmitoleic:stearic acid ratio (an estimate of SCD activity) was greater (P < 0.001) in the subcutaneous adipose tissues from brisket, plate, and round than in the loin, rib, and sirloin. Conversely, subcutaneous adipose tissue from the loin, rib, and sirloin had greater (P < 0.001) SCD gene expression than the brisket, plate, and round. In general, subcutaneous adipose tissues with the highest concentration of MUFA and least SFA consistently exhibited the least SCD gene expression and adipogenic gene expression. We conclude that MUFA in the brisket and other depots with large SCD indices were deposited before 9 mo of age, during a time when the subcutaneous adipocytes were highly differentiated.
我们已经证明，在胴体脂肪组织中，胸肉皮下脂肪组织含有最高浓度的 MUFA 和最低浓度的 SFA。因此，我们假设胸肉皮下脂肪组织的脂肪生成基因表达会随着时间的推移而高于其他主要的皮下脂肪组织。选择 4 头安格斯公牛，每个公牛的年龄为 9、12、14 和 16 个月，收获并从胸肉、肩部、肋骨、腰部、臀肉、后腿、侧腹和胸腹部采集新鲜的皮下脂肪组织样本。通过定量实时 PCR 分析 C/EBPβ、PPARγ、肉碱棕榈酰转移酶-1β（CPT-1β）、硬脂酰辅酶 A 去饱和酶（SCD）、AMP 激活蛋白激酶α（AMPKα）和 G 蛋白偶联受体 43（GPR43）的相对基因表达。C/EBPβ、PPARγ 和 CPT-1β 的表达在 12 至 14 月龄时最高（均 P < 0.0001），并且在所有部位的 16 月龄时下降到非常低的丰度。PPARγ 和 CPT-1β 的表达在侧腹、肋骨和臀肉皮下脂肪组织中高于胸肉和后腿脂肪组织（P < 0.03）。SCD 基因的表达在 4 个年龄组之间没有差异（P = 0.95）。棕榈油酸：硬脂酸比值（SCD 活性的估计值）在胸肉、盘和后腿皮下脂肪组织中高于腰部、肋骨和臀肉。相反，腰部、肋骨和臀肉的皮下脂肪组织的 SCD 基因表达高于胸肉、盘和后腿。一般来说，MUFA 浓度最高和 SFA 浓度最低的皮下脂肪组织始终表现出最低的 SCD 基因表达和脂肪生成基因表达。我们得出结论，MUFA 在胸肉和其他 SCD 指数较高的部位的沉积发生在 9 个月之前，此时皮下脂肪细胞高度分化。
