绵羊肌肉中FAS基因和HSL基因的发育性变化及其对肌内脂肪含量的影响(英文)

Developmental Changes of the FAS and HSL mRNA Expression and Their Effects on the Content of Intramuscular Fat in Kazak and Xinjiang Sheep

选取不同日龄的雄性哈萨克羊和新疆细毛羊共54只，屠宰后取背最长肌，用索氏抽提法检测肌内脂肪（intramuscularfat，IMF）含量，用荧光实时定量PCR法检测肌肉脂肪酸合成酶（fatty acid synthase，FA回和激素敏感脂肪酶（hormone—sensitive 1pase，HSL）基因表达的发育性变化，并分析基因表达对肌内脂肪沉积的影响。结果表明：1）随着日龄的增加，雄性哈萨克羊的IMF含量持续上升，各生长时期差异显著（P〈0．05），而新疆细毛羊的IMF含量在各生长时期无显著差异（P＞0．05）。雄性哈萨克羊的IMF含量30～90日龄期间极显著高于新疆细毛羊（P〈0．01）。2）FAS基因mRNA水平在哈萨克羊肌肉中初生时最高（P〈0．05），然后随日龄的增加呈下降趋势；在新疆细毛羊肌肉中，FASmRNA水平表现出“下降-上升-下降-上升”的发育模式，其中60日龄显著高于90日龄（P〈0．05），其余日龄之间差异不显著。HSL基因在2品种绵羊肌肉中的表达模式基本类似，在哈萨克羊肌肉中随年龄的增加而下降，初生时的水平显著高于60～90日龄（P〈0．05）；在新疆细毛羊中30日龄时达到最高（P〈0．01），到60日龄时下降到最低（P〈0．05），随后保持这种低表达水平。3）FAS和HSL基因mRNA的表达量均与哈萨克羊IMF含量呈负相关，相关系数分别为：r=-0．485（P=0．02），r=-0．423（P=0．05）；在哈萨克羊中两基因表达量水平比值（FAS：HSL）与IMF呈极显著负相关r=-0．552（P=0．01）。在新疆细毛羊中两基因的表达水平及比值均与IMF无显著相关性（P〉0．05）。

Twenty-four male Kazak sheep and 30 Xinjiang fine wool sheep at different ages were selected to investigate the development-dependent expression levels of fatty acid synthase （FAS） gene and hormone-sensitive lipase （HSL） gene in muscle and their effects on the contents of intramuscular fat （IMF）. Longissimus dorsal muscle was sampled to measure IMF and total RNA was extracted to determine FAS and HSL mRNA expression levels by real-time PCR. The results showed that： l） The IMF content increased continuously with growth and showed significant differences （P 〈 0.05） between different age groups in male Kazak sheep, but in Xinjiang fine wool sheep there was no such difference observed. Furthermore, the IMF contents in Kazak were much higher （P 〈 0.01） than that of the other breed from day 30 to 90. 2） FAS mRNA expression level was the highest （P 〈 0.05） on day 0 in Kazak sheep and then declined with growth, in the other breed the gene showed a d‘ecline-rise-decline-rise＇ expression manner as the animals grew. HSL mRNA expression level had a similar model in two breeds, in Kazak sheep it was the highest on day 0 （P 〈 0.05） and in Xinjiang fine wool sheep on day 30 （P 〈 0.01）, then both decreased after this term. 3） In male Kazak sheep, FAS and HSL mRNA expression level were both negatively related to IMF content （r= -0.485 （P = 0.02）, r= -0.423 （P = 0.05））, and the ratio of FAS/HSL expression exhibited significantly negatively related IMF contents. In male Xinjiang sheep, there were no obvious relationship between FAS and HSL expression and IMF content （P 〉 0.05）.