猪delta-5脂肪酸去饱和酶基因序列与肌内多不饱和脂肪酸...

猪delta-5脂肪酸去饱和酶基因序列与肌内多不饱和脂肪酸... 豬delta-5脂肪酸去飽和酶基因序列與肌內多不飽和脂肪酸含量和生產性能關係研究 Study on Delta-5 Fatty Acid Desaturase Gene Sequence and Its Association with Intramuscular Polyunsaturated Fatty Acids Content and Production Performances in Pig 研究生,陳婉婷 Chen, Wan-Ting 指導教授,張秀鑾 Chang, Hsiu-Luan 【摘要】 多不飽和脂肪酸,polyunsaturated fatty acid, PUFA,為人類所需之重要營養成分,不僅是細胞膜磷脂質之重要組成物質,且在細胞訊號傳遞上扮演重要角色。哺乳動物delta-5脂肪酸去飽和酶,delta-5 fatty acid desaturase, D5FAD,為一種膜結合去飽和酶,主要功能為參與動物體內PUFA之生合成,進而產生花生四烯酸,arachidonic acid, AA,、eicosapentaenoic acid,EPA,和docosahexaenoic 2acid,DHA,。研究指出豬肉肌內脂肪酸含量具中高遺傳性,h估值介於0.20與0.79,,其組成分受遺傳,品種和性別,和環境,飼養管理和營養成分,等因素影響,且與人類心血管疾病有關,故歐洲衛生機構建議人類膳食肉類之PUFA (P) 與飽和脂肪酸,saturated fatty acid, S,含量比,PUFA/SFA,應高於0.4,而PUFA中ω-6與ω-3含量比,ω-6/ω-3,則應小於4.0。本研究旨在探討豬隻delta-5脂肪酸去飽和酶基因與其肌內PUFA含量和生產性能之關係。應用聚合酶連鎖反應,polymerase chain reaction,技術進行豬D5FAD基因增殖與定序,獲得長度1,338 bps之全長序列,可轉譯出446個胺基酸,且完成NCBI基因庫註冊與取得EU131180序號,accession number,。經與人類、大鼠和小鼠D5FAD基因序列比對發現,豬與大鼠和小鼠具84% 同源性,而與人類有89% 同源性。豬隻八種不同器官組織之D5FAD mRNA現量結果顯示,肝臟表現量最多,心臟次之。應用D5FAD基因第933與1019個核苷酸之雙變異點,T933C與C1019G,,進行肉豬組合基因型分析。結果顯示,閹公豬和女豬以TT-GG基因型者居多,54.20和53.98%,,TC-CG型者,28.57和26.11%,次之。基因型效應評估指出,T933C與C1019G突變點分別為TC與GG基因型者,肌內PUFA含量,分別顯著地較同一突變點其他基因型者為高。同時,ω-3含量最低14% 豬隻具T933C-TT基因型之頻率顯著地高於ω-3含量最高14% 豬隻組,但其T933C-TC基因型頻率則顯著地較低。相同趨勢亦見於DPA與DHA含量最高與最低14% 豬隻組之比較。C1019G基因型頻率分布比較發現,GG基因型頻率不論在最高14% ALA或ω-6含量組,均較低含量組者為高。肉豬屠體性狀評估發現,T933C-CC型豬隻有較重之腹脅肉、較高屠體主要部位肉率、瘦肉量、前軀骨骼重與大理石紋評分。同時,C1019G-GG基因型豬隻總骨骼重和前骨骼重均較重。品種內T933C 和C1019G基因型豬隻生長性能比較顯示,T933C-CC基因型杜洛克公豬有較佳之飼料效率與較早 達110 kg重之傾向,相同趨勢亦見於藍瑞斯公豬。此外,C1019G-CC基因型藍瑞斯公豬有較佳之 飼料效率。綜合上述,應用D5FAD基因多態性資訊於豬隻生產體系中,生產健康與優質畜產品, 值得進一步評估與探討。 關鍵字,delta-5 脂肪酸去飽和酶、豬、多不飽和脂肪酸、生產性狀 【Abstract】 Long chain polyunsaturated fatty acids (PUFAs) are essential nutrient in human diet, which serves as structural components of cell membranes, and play key roles in cell signal transduction. Delta-5 fatty acid desaturases (D5FAD) of mammals are membrane bound desaturases, which mainly involve in the biosynthesis of PUFAs, and result in AA, EPA and DHA production. Research indicated that the 2heritabilities were moderate to high for intramuscular fatty acids ( h=0.20-0.79) in pork. In addition, the corresponding compositions affected by genetic (breeds and gender) and environment (feeding system and nutrition composition), are associated with coronary heart disease in modern life. The ratio of PUFA to saturated fatty acid (SFA) recommended by the health related organizations in Europe was above 0.4 and the ratio of ω-6/ω-3 PUFA was less than 4. The objectives of this study were to fullfil the D5FAD gene full sequence and to evaluate its association with intramuscular polyunsaturated fatty acids content and production performances in pig. Polymerase chain reaction technique was used to amplify the pig D5FAD cDNA full length (1,338 bps), which was then sequenced and further encoded peptide with 446 amino acids. The alignements of corresponding sequence displayed 84% and 89% nucleotide homology with the rodent (mouse and rat) and human, respectively. Tissues from brain, heart, liver, lung, spleen, pancreas, testis and skeletal muscle of pig were conducted for mRNA expression. Results showed that the liver was the most abundant expression tissue, followed by heart tissue. Two point mutations (T933C and C1019G) located at the 933th and 1019th positions, respectively, were found in D5FAD gene and were further genotyped for carcass evaluation. TT-GG combination of corresponding point mutations was the most popular genotype in both barrows and gilts, which accounted for 54.20% and 53.98%, repectively. However, TC-CG combination followed with frequencies being 28.57 and 26.11%. Within single point muation comparison, hogs with TC and GG genotypes showed significantly more PUFA content in intramuscular fat than those of other genotypes for T933C and C1019G, respectively. Furthermore, hog was classified into one of three (namely the lowest 14%, the highest 14% and just between) groups based on fatty acid content in corresponding these item were evaluated. Hogs in the lowest ω-3 group showed significantly higher and lower frequencies for T933C-TT genotype, respectively, than those of in the highest group ones. Similar trends were also observed in DPA and DHA comparisons. Also, hogs with C1019G-GG genotype were more popular in the highest ALA and ω-6 groups than those in the lowest ones. Hogs with T933C-CC genotype had heavier belly muscle (%), major lean mass (%), lean meat weight (kg), and higher bone weight in fore carcass (%) as well as meat color (score). Higher total bone (%) and bone weight in fore carcass (%) were shown in hogs with C1019-GG genotype. In addition, Duroc boars with T933C-CC genotype showed better feed efficiency and tended to reached 110 kg off-test weight earlier. Similar trend was also observed in Landrace boars with T933C-CC and C1019G-CC genotypes for feed efficiency comparisons. In conclusion, D5FAD-T933C and C1019G polymorphisms would deserve further recognition for healthy and high functional pork production in Taiwan pig industry. Keywords,Delta-5 fatty acid desaturase, Pig, Polyunsaturated fatty acid, Production trait