湖羊GHR和IGF-Ⅰ基因表达的发育性变化 及其与肉质性状的关联

 【目的】探讨生长激素受体（growth hormone receptor，GHR）和胰岛素样生长因子-Ⅰ（insulin-like growth factor-Ⅰ，IGF-Ⅰ）基因在湖羊不同生长阶段背最长肌中表达丰度与肉质性能的相关性以及这两个基因表达水平的关联性，为湖羊肌肉生长性状的选育提供遗传学资料。【方法】利用荧光定量RT-PCR分析GHR和IGF-Ⅰ基因在湖羊早期生长背最长肌肉组织中的mRNA的发育性变化。【结果】①出生后随着月龄的增加，母羊GHR基因在背最长肌的表达趋势为：先升高后降低再升高再降低最后再升高，最后6月龄到达最高点；公羊GHR在背最长肌的表达趋势为：先升高到2月龄到达一个峰值，2月龄到4月龄为一个降低的过程，4月龄到6月龄又升高，并到达最高点；母羊IGF-Ⅰ基因在背最长肌的表达趋势为：由2日龄开始依次升高最后于6月龄到达最高点；公羊IGF-Ⅰ基因在背最长肌的表达趋势为：先升高到1月龄到达一个峰值，1月龄到3月龄为一个降低的过程，并于3月龄降至与初生接近相等的水平，此后随月龄增加逐渐升高，并于6月龄到达最高点；②GHR和IGF-Ⅰ基因在湖羊各月龄间大多存在显著或极显著差异，湖羊的公羊和母羊的GHR和IGF-Ⅰ基因的相同生长阶段的表达也大多存在显著或极显著差异；③GHR和IGF-Ⅰ基因的表达存在显著正相关（0.01＜P＜0.05），GHRI和GF-I基因与肌纤维直径均存在极显著正相关（P＜0.01），GHR与肌纤剪切力存在极显著正相关（P＜0.01），IGF-Ⅰ与肌纤剪切力存在显著正相关（0.01＜P＜0.05），GHR和IGF-Ⅰ基因与肌纤维密度均存在极显著负相关（P＜0.01）。【结论】性别和年龄对于GHR和IGF-Ⅰ基因在湖羊不同生长阶段的肌肉中的表达具有重要影响；出生后，各基因表达水平并非随之上升或者下降，各基因表达水平出现拐点的时间并不相同；GHR和IGF-Ⅰ基因在湖羊早期肌肉性状的表达为显著正相关，可以作为湖羊早期肉质性状的候选基因。

Developmental Changes of Gene Expression of GHR and IGF-Ⅰ Genes and Their Association Analysis with Meat Quality Traits in Hu Sheep

【Objective】The objective of this study was to discuss the developmental changes of gene expression of growth hormone receptor (GHR) and insulin-like growth factor-Ⅰ(IGF-Ⅰ) and their association analysis with meat quality traits , and the relationship of the expression level between GHR gene and IGF-Ⅰgene in Hu sheep. 【Method】The developmental changes of gene expression of GHR gene and IGF-Ⅰgene on the early growth of Hu sheep were detected by real-time fluorescent quantitative RT-PCR. 【Result】The results were as followes: With increasing age after birth, the GHR expression trend of ewes was up-down-up-down-up, and 6-month reached the top. The GHR expression trend of rams was that 2-day-old to 2-month-old was increasing, 2-month-old to 4-month-old was decreasing, 4-month-old to 6-month-old was increasing and reached the top. With the increasing age after birth, the IGF-Ⅰgene expression trend of ewes was increasing from 2-day-old to 6-month-old which had the top expression. The IGF-Ⅰgene expression trend of rams was that at 2-day-old firstly increased to a peak at one-month-old, 1-month-old to 3-month-old had a decreasing process and reached the same level which was close to the newborn, and then increased with the increasing age, and 6-month-old reached the top. Most growth phases had a significant difference or extreme significant difference in GHR and IGF-Ⅰand the expressions of GHR and IGF-Ⅰbetween most rams and ewes that at the same growth phase had a significant difference or extreme significant difference. The results showed that the expressions of GHR and IGF-Ⅰhad a significant positive correlation, (0.01＜P＜0.05) the expressions of GHR and IGF-Ⅰgenes had a extreme significant positive correlation (P＜0.01) with diameter of muscle fibers and a extreme significant negative correlation (P＜0.01) with density of muscle fibers, and the expressions of GHR had a extreme significant positive correlation (P＜0.01) with shear force of muscle fibers, the expression of IGF-Ⅰhad a significant positive correlation with shear force of muscle fibers (0.01＜P＜0.05). 【Conclusion】The results showed that different stages and different genders had important influences on the expressions of GHR and IGF-Ⅰgenes in sheep skeletal muscle. After birth, the expressions of the two genes did not always increase or decrease, the turning points of different genes expression were not at the same time. The expression of GHR and IGF-Ⅰhad a significant positive correlation in early muscle traits of Hu sheep. GHR and IGF-Ⅰgene can be regarded as the candidate gene for the trait of meat quality in Hu Sheep.