Exploration of unutilized feed resource to regulate muscle fiber type

制备了含有小鼠PGC-1α启动子的基于荧光素酶的PGC-1α报告基因(PGC-1α(-2553)-Luc)。对33种饲料的乙醇提取物的筛选表明，乌龙茶和炒绿茶提取物降低了C2C12成肌细胞PGC-1α(-2553)-Luc的表达。我们进一步研究了茶渣及其青贮料的乙醇提取物对PGC-1α转录的影响；茶渣青贮提取物抑制了PGC-1α的转录。生茶叶提取物、茶叶废料和茶叶废料青贮料处理能有效降低肌卫星细胞发生过程中PGC-1α的mRNA水平。然而，屠宰前2个月饲喂茶渣青贮料并没有降低日本黑肥牛肌肉中PGC1a基因的表达水平，而是增加了红纤维型肌球蛋白重链Myh7mRNA的表达，因此，肌肉中PGC1a的表达与肌球蛋白重链之间没有明显的关系。

A luciferase-based Pgc-1 alpha reporter construct (Pgc-1 alpha(-2553)-luc) that contains the mouse Pgc-1 alpha promoter was prepared. A screen of ethanol extracts from 33 feedstuffs indicated that oolong tea and roasted green tea extracts decreased Pgc-1 alpha(-2553)-luc expression in C2C12 myoblasts. We further examined the effects of the ethanol extracts of tea waste and its silage on Pgc-1 alpha transcription; the tea waste silage extract inhibited Pgc-1 alpha transcription. Treatment with the extracts of raw tea leaves, tea waste and tea waste silage effectively decreased Pgc-1 alpha mRNA levels during myogenesis of myosatellite cells. However, feeding tea waste silage for 2 months before slaughter did not decrease muscular Pgc1 alpha mRNA level in Japanese Black fattening steers, but increased mRNA expression of Myh7, the red-fiber type myosin heavy chain, and thus no clear relationship was detected among expression of Pgc1 alpha and the myosin heavy chain in the muscle.