豬 Myostatin 和 IGF-2 基因多態性與生長、屠體及繁殖性狀相關性之探討

Genetic variations and polymorphisms for porcine Myostatin and IGF-2 genes related to growth, carcass and reproductive traits

陳薏婷(Yi-Ting Chen)

指導教授 ： 王佩華

國立臺灣大學/生物資源暨農學院/動物科學技術學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.02899

摘要

Myostatin（MSTN）為 Transforming growth factor-β（TGF-β）家族成員之一，在許多物種間具有高度保留性，目前已知其主要功能為抑制骨骼肌發育。自 1997 年發現Belgian牛隻 MSTN 基因突變造成雙肌（double-muscled）的外表型，陸續在特賽爾羊（Texel）、人類、小靈犬（Whippet）等哺乳類動物中亦發現類似情形，並已證實其雙肌現象均由 MSTN 基因自然突變，使 MSTN 蛋白質失去抑制骨骼肌發育之功能所造成。然而，在豬隻 MSTN 基因中目前尚未發現功能性的突變（functional mutation），也沒有所謂的雙肌品種豬隻。
本試驗目的為探討豬隻 MSTN 和 IGF-2 基因多態性對豬生長性能、屠體性狀和繁殖能力之影響。試驗動物包括﹕分析生長性能試驗的 1,743 頭杜洛克（Duroc）、944 頭藍瑞斯（Landrace）和 343 頭約克夏（Yorkshire）純種豬；分析屠體性狀試驗的 270 頭杜洛克 × 藍瑞斯（Duroc × Landrace, DL）以及 153 頭杜洛克 × 約克夏 × 藍瑞斯（Duroc × Yorkshire × Landrace, DYL）雜交豬；以及分析繁殖能力試驗的 528 頭純種藍瑞斯母豬。性狀收集包括平均日增重（average daily gain, ADG），飼料效率（feed efficiency, FE），背脂厚度（ultrasound backfat thickness, BF），70 和 150 日齡體重（body weight at 70 days-old, BW70 and 150 days-old, BW150），達 110 公斤體重之日齡（days to 110 kg of body weight, D110 kg），第十肋腰眼面積（longissimus muscle area, LMA），屠體背脂厚度，分切部位前段、中段和後段的瘦肉及脂肪重，屠體總瘦肉重，屠體總瘦肉百分比，各胎的分娩頭數（total number born, TNB）及生產頭數（number of born alive piglets, NBA）。利用 Taqman SNP Genotyping Assay 分析 MSTN 基因啟動子區域 g.435G>A 和 g.447A>G 以及 IGF-2 基因第七內含子區域 g.162C>G 位點之基因型。
在基因型與表型的相關分析結果發現，MSTN 基因啟動子區域基因型為 g.435GG/447AA 的杜洛克有顯著較高的平均日增重、150 日齡體重和顯著較低的達 110 公斤日齡（P<0.01）；於藍瑞斯也有顯著較高的平均日增重和顯著較低的達 110 公斤日齡（P<0.05）；而約克夏亦有顯著較高的平均日增重和顯著較低的達 110 公斤日齡（P<0.05），但有較重之 150 日齡體重與較薄之背脂厚度的趨勢（P<0.1）。IGF-2 基因第七內含子區域基因型為 g.162CC 的藍瑞斯有較高之平均日增重的趨勢（P<0.1）；而約克夏則有較重之 70 日齡體重和較低之背脂厚度的趨勢（P<0.1）。IGF-2 基因第七內含子區域 g.162GG 的 DL 及 DYL 雜交豬有顯著較厚的第十肋和最後肋背脂厚度（P<0.05），屠體前段脂肪重也有較重之趨勢（P<0.1）。此外，MSTN 基因啟動子區域 g.435G>A/447A>G 和 IGF-2 基因第七內含子區域 g.162C>G 位點間之交互作用對豬隻生長性能和屠體性狀並無影響。藍瑞斯純種母豬的繁殖性能相關性試驗結果顯示，MSTN 基因啟動子區域 g.435G>A/447A>G 的基因型對分娩頭數有影響之趨勢；然而，在基因型間無顯著差異存在。
根據上述結果知，MSTN 基因啟動子區域 g.435G>A/447A>G 和 IGF-2 基因第七內含子區域 g.162C>G位點可以成為有潛力的遺傳輔助標幟，並應用於育種選拔上。選拔 MSTN 基因啟動子區域 g.435G/447A 交替基因以提高豬隻體重及生長速率；選拔 IGF-2 基因第七內含子區域 g.162C 交替基因以提高豬隻體重和降低脂肪之累積；而 MSTN 基因啟動子區域 g.435G>A/447A>G 可能不適合應用在豬隻繁殖能力選拔上，換言之，利用此標幟進行豬隻生長性能及屠體性狀育種選拔時，可能不會影響豬隻的繁殖能力。

關鍵字

豬隻經濟性狀 ； 類胰島素生長因子-2 ； 分子輔助選拔 ； 肌肉抑制激素

並列摘要

Myostatin (MSTN), a member of transforming growth factor-β (TGF-β) superfamily, is a negative regulator of muscle development. Loss-of-function of MSTN protein resulted in double-muscled phenotype in several mammalian species, such as cattle, sheep, human, and dog have been found. However, there was no functional mutation in porcine MSTN gene. Therefore, there was no so-called double-muscled breed of pig.
The aim of this study was to investigate the effects of polymorphisms of MSTN and IGF-2 genes on porcine growth performance, carcass, and reproductive traits. DNA from purebred and crossbred pigs were extracted, including 1,743 Duroc, 944 Landrace, and 343 Yorkshire for growth performance analysis; 270 Duroc × Landrace (DL) and 153 Duroc × Yorkshire × Landrace (DYL) for carcass traits analysis; 528 Landrace sows for reproductive performance analysis. Data of average daily gain (ADG), feed efficiency (FE), ultrasound backfat thickness (BF), body weight at 70 days-old (BW70) and 150 days-old (BW150), days to 110 kg of body weight (D110 kg), longissimus muscle area (LMA) at 10th rib, carcass backfat thickness, meat and fat weight in the anterior, middle, and posterior cuts of carcass, total lean weight and percentage, and total number born (TNB) and number of born alive piglets (NBA) of each parity were collected. Two SNPs (g.435G>A and g.447A>G) in the promoter region of MSTN gene and one SNP (g.162C>G) in the intron 7 of IGF-2 gene were genotyped using Taqman SNP Genotyping Assay.
The association results indicated that the MSTN g.435GG/447AA individuals had better ADG, heavier BW150, and lower Age110kg (P<0.05) in Duroc pigs; better ADG (P<0.05) in Landrace pigs; greater ADG and BW150, and lower BF and Age110kg (P<0.1) in Yorkshire. The IGF-2 g.162CC individuals had better BW70, and thinner BF (P<0.1) in Yorkshire pigs. The IGF-2 g.162GG individuals were found to have significant thicker backfat at 10th and last rib (P<0.05), and higher fat weight in the anterior cuts of carcass (P<0.1) in DL and DYL crossbred pigs. Additionally, there were no significant interactions between MSTN g.435/447 and IGF-2 g.162 on growth performance and carcass traits. In Landrance sow’s reproductive trait showed that there were no significant difference between the genotype of MSTN g.435G>A/447A>G and the TNB or NBA observations.
In conclusion, these two loci are potential genetic markers in porcine selection of growth performance and carcass traits, and they could be used independently. Selection for MSTN g.435G/447A allele is expected to increase body weight and growth rate in Duroc and Yorkshire pigs. Furthermore, selection for IGF-2 intron 7 g.162C allele is expected to increase body weight and decrease fat accumulation in Yorkshire, DL and DYL pigs. However, the genotype of MSTN g.435/447 might not affect the litter size in Landrace sows.

並列關鍵字

Economic Traits of pigs ； Insulin-like growth factor-2 gene ； Marker-assisted selection (MAS) ； MSTN gene

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