绵羊肌肉LPL基因表达的发育性变化及其对肌内脂肪含量的影响

Developmental Changes of the LPL mRNA Expression and the Effect on IMF Content in Sheep Muscle

【目的】研究绵羊肌肉中脂蛋白脂酶(lipoprotein lipase,LPL)基因mRNA的发育性变化规律及其对肌内脂肪沉积的影响。【方法】选取2、30、60、90和120日龄的雄性哈萨克羊和新疆细毛羊各6只(120日龄只有新疆细毛羊),屠宰后取背最长肌检测肌内脂肪含量,用荧光实时定量PCR法检测肌肉LPL基因mRNA表达水平,分析在不同时期的变化及其与肌内脂肪含量的关系。【结果】随着日龄的增加,雄性哈萨克羊的IMF(IntramuscularFat)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30～90d期间极显著高于新疆细毛羊(P<0.01);雄性哈萨克羊肌肉LPL基因的表达量在2日龄时最高,60日龄时降到最低,然后逐渐上升,2日龄时LPL表达量极显著高于其它日龄(P<0.01)。新疆细毛羊的表达量在2日龄时较低,30日龄时升到最高,随后下降,到90日龄时降到最低,然后又逐渐上升;30日龄表达量与2、90、120日龄差异极显著(P<0.01),与60日龄差异显著(P<0.05);60日龄表达量与2、90、120日龄差异显著(P<0.05);哈萨克羊LPL基因2～60日龄的表达量与IMF含量呈负相关,相关系数为-0.625(P<0.05);新疆细毛羊IMF含量与LPL基因表达量无显著相关性。【结论】新疆细毛羊和哈萨克羊背最长肌肌内脂肪沉积的发育性变化不同,在生长发育早期,哈萨克羊随日龄的增加其IMF上升,新疆细毛羊在各时期保持一个稳定的水平;LPL基因在哈萨克羊生长早期对其肌内脂肪的沉积可能有负调控作用,而对新疆细毛羊无明显作用。

[Objective] The objectives of this study were to investigate the developmental changes of the Lipoprotein lipase （LPL） mRNA level in sheep muscle and its effect on intramuscular fat （IMF） accumulation. [Method] Male Kazak and Xinjiang merino sheep at 2 to 120 days old were selected to investigate the developmental changes of lipoprotein lipase mRNA expression and its effect on intramuscular fat content in muscle. Six animals of each breed were slaughtered at 2, 30, 60, 90 and 120 days （only the Xinjiang merinos at 120 days old were available） to collect samples from longissimus dorsi muscle. This was done for the purpose of determining the IMF content and extracting total RNA for investigating the developmental changes of the LPL mRNA expression by real-time PCR. [ Result] In male Kazak sheep, the IMF content increased with the progress of development. There were significant differences （P 〈 0.05） between the age groups. However, there were no differences （P 〉 0.05） between age groups in Xinjiang merinos. The IMF content of the male Kazak sheep was significantly higher （P 〈 0.01） than that of the Xinjiang merinos aged from 30 to 90 days. LPL mRNA expression was the highest at day 2 and it was significantly higher than that of all other age groups （P 〈 0.01）, while animals at 60 days old had the lowest LPL mRNA expression in the male Kazak sheep. In Xinjiang merino sheep, the LPL mRNA was the highest at 30 days old （P 〈 0.01）, followed by a continuous decrease down to the lowest level at 90 days old, then it slightly increased. In male Kazak sheep at 2 to 60 days old, the LPL mRNA expression was negatively correlated to the IMF content （γ=-0.625, P 〈 0.05）, however, no such relationship was detected in the male Xinjiang merinos. [ Conclusion] There were different models of IMF accumulation in male Kazak and Xinjiang merino sheep, the IMF content increased with the age increasing in Kazak sheep and had not significantly changed in Xinjiang merinos in the early development stage; LPL maybe have a negative effect on IMF accumulation in Kazak sheep at early stages.