王夢(mèng)琦 倪煒 唐程

摘要 [目的]探索FADS2基因 c.1571 A>G多態(tài)性對(duì)中國(guó)荷斯坦牛泌乳性狀的影響。[方法]對(duì)866頭中國(guó)荷斯坦牛FADS2基因c.1571 A>G位點(diǎn)進(jìn)行多態(tài)性分析，采用最小二乘法分析其對(duì)泌乳性狀的影響。[結(jié)果]FADS2 c.1571 A>G 對(duì)日產(chǎn)奶量、乳蛋白率、乳脂率、總固形物以及尿素氮含量等泌乳性狀有顯著影響（P<0.05）。GG基因型個(gè)體具有較高的日產(chǎn)奶量，而AA型個(gè)體的乳脂率、乳蛋白率及總固形物含量顯著高于其他基因型個(gè)體。 FADS2 c.1571 A>G突變對(duì)體細(xì)胞評(píng)分（SCS）無顯著影響（P>0.05）。[結(jié)論]FADS2可作為優(yōu)化中國(guó)荷斯坦牛泌乳性能的潛在分子標(biāo)記。

關(guān)鍵詞 FADS2;c.1571 A>G;體細(xì)胞評(píng)分;泌乳性狀

中圖分類號(hào) S813.1文獻(xiàn)標(biāo)識(shí)碼 A

文章編號(hào) 0517-6611（2019）10-0092-02

Abstract [Objective]To explore the effects of c.1571 A>G polymorphism of FADS2 gene on the lactation traits of Chinese Holstein cows.[Method] The single nucleotide polymorphisms （SNPs） of c.1571 A>G mutation of FADS2 gene in Chinese Holstein cows （n=866） were analyzed，and their effects on the lactation traits of Chinese Holstein cows were analyzed by using least square method.[Result] c.1571 A>G mutation of FADS2 gene had significant effects on daily milk yield，milk protein content，milk fat content，total solids and urea nitrogen content，and other milk production traits （P<0.05）. The individuals with GG genotype had significantly higher daily milk yield，while the individuals with AA genotype had significantly higher milk fat content，milk protein content and content of total solids.FADS2 c.1571 A>G mutation had no significant effect on SCS.[Conclusion] FADS2 could be used as the potential molecular markers for improving the? lactation performance of Chinese Holstein cows.

Key words FADS2;c.1571 A>G mutation;Somatic cell score（SCS）;Lactation traits

泌乳性狀是奶牛長(zhǎng)期選擇育種所依據(jù)的主要經(jīng)濟(jì)性狀，如日產(chǎn)奶量、乳脂率、乳蛋白率、乳糖含量、總固形物和乳中尿素氮等[1]。經(jīng)濟(jì)性狀通常受多基因的調(diào)控，因此探索對(duì)這些性狀有較大影響的基因尤為重要[2]。然而，目前只發(fā)現(xiàn)少數(shù)的突變與牛奶組成相關(guān)[3]。

脂肪酸去飽和酶（fatty acid desaturases，F(xiàn)ADS）是脫氫酶家族的成員，通過脫氫作用在脂肪酸鏈特定位置上催化C-C 轉(zhuǎn)換成C=C[4]，對(duì)脂肪酸向多不飽和脂肪酸的轉(zhuǎn)化起催化作用。FADS1和FADS2基因調(diào)控多不飽和脂肪酸代謝路徑并影響血漿中的多不飽和脂肪酸含量[5]。Matsumoto等[6]發(fā)現(xiàn)FADS2 g.-823G>A 對(duì)牛肉品質(zhì)評(píng)分有顯著影響。IbeaghaAwemu 等[7]報(bào)道了加拿大荷斯坦牛FADS2基因的33個(gè)SNPs，并發(fā)現(xiàn)FADS2基因3 非轉(zhuǎn)錄區(qū)域（3 untranscript region，3UTR）c.1571 A>G 和 c.2776 A>G 與牛奶中多不飽和脂肪酸含量顯著相關(guān)。 Fatima等[8]報(bào)道產(chǎn)后奶牛處于能量負(fù)平衡時(shí)FADS2基因表達(dá)下調(diào)。以上研究表明FADS2與泌乳性狀有潛在影響，但FADS2與泌乳性狀（如產(chǎn)奶量、乳脂率以及乳蛋白率等）的關(guān)系并不確定。筆者探討了FADS2基因c.1571 A>G突變對(duì)中國(guó)荷斯坦牛泌乳性狀的潛在影響。

1 材料與方法

1.1 試驗(yàn)動(dòng)物與泌乳性狀收集

從江蘇省某大型荷斯坦牛奶牛場(chǎng)采集866頭中國(guó)荷斯坦泌乳奶牛血液樣本，用于提取DNA。同時(shí)，采集2013年6月至2016年12月DHI生產(chǎn)記錄，共來自866頭奶牛2 198個(gè)泌乳周期的20 532條測(cè)定日生產(chǎn)記錄用于表性分析，性狀主要包括日產(chǎn)奶量、乳脂率、乳蛋白率、脂蛋白比、體細(xì)胞數(shù)、SCS、乳糖、總固體和尿素氮。

1.2 DNA 提取、SNP 分型以及miRNA 結(jié)合位點(diǎn)預(yù)測(cè)

采用標(biāo)準(zhǔn)的苯酚-氯仿法從中國(guó)荷斯坦牛血液中提取DNA[9]。根據(jù)FADS2基因序列（BC123735.1），采用飛行時(shí)間質(zhì)譜法檢測(cè)FADS2基因3UTR區(qū)c.1571 A>G SNP突變。使用Target Scan7.0軟件預(yù)測(cè)變異位點(diǎn)結(jié)合的miRNA。

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