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  • 學位論文

豬隻不同品種及部位肌肉之脂質代謝相關基因表現

Expression of lipid metabolism-related genes in different muscles and different breeds of pigs

指導教授 : 王佩華
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摘要


肉中的肌內脂肪能夠影響肉之柔嫩度(tenderness)、多汁性(juiciness)及風味(flavor),在進行屠宰時常發現,臺灣本土黑豬其肌內脂肪含量高於瘦肉型洋種豬,而前人研究中對於豬隻基因表現與肉質相關的研究則常著重在背最長肌。因此,本研究除了比較臺灣黑豬與洋種豬的背最長肌之脂質代謝相關基因表現差異,亦同時納入分析肩胛與後腿其脂質代謝基因表現,探討不同豬種以及不同肌肉間的肌內脂肪累積潛能。 本試驗豬隻包括來自行政院農委會高雄種畜繁殖場之14頭高畜黑豬,以及來自民間豬場之14頭洋種豬(包含7頭藍瑞斯與7頭杜洛克)與16頭黑豬;收集其屠體性狀資料(屠體重、屠體長、第一肋、最後肋及最後腰椎三點平均背脂厚度)。此外,採集其第10至11肋間背最長肌、肩胛半棘肌與後腿股直肌之肌肉樣本以抽取RNA,並以即時定量聚合酶(real-time PCR)SYBR法偵測其脂質代謝相關基因表現,包括ATGL、SCD、 HSL、LDLR、SREBP1c、CPT1b、FAS、Leptin 以及H-FABP。 試驗結果顯示,在高畜黑豬及民間黑豬的背最長肌及半棘肌中,其脂質生成相關基因SREBP1c及H-FABP的表現,顯著高於洋種豬(P<0.05),而其脂質氧化基因CPT1b顯著低於洋種豬(P<0.05),但高畜黑豬及民間黑豬兩者間沒有顯著差異;此外,洋種豬半棘肌之脂質分解相關基因Leptin的表現顯著高於高畜黑豬及民間黑豬,但兩種黑豬間則無顯著差異。在股直肌中,高畜黑豬與民間黑豬之脂質分解相關基因Leptin的表現顯著低於洋種豬(P<0.05),但高畜黑豬與民間黑豬兩者間沒有顯著差異;而民間黑豬其脂質生成相關基因SREBP1c顯著高於高畜黑豬及洋種豬(P<0.05),但高畜黑豬及洋種豬兩者間沒有顯著差異,脂肪酸轉運基因H-FABP表現於三者之股直肌中以民間黑豬最高,高畜黑豬次之,洋種豬最低(P<0.05)。 在不同肌肉部位的比較中,高畜黑豬中在股直肌之H-FABP、FAS與SREBP1c表現顯著低於其背最長肌及半棘肌(P<0.05),且在背最長肌及半棘肌之間並沒有顯著差異;然而,背最長肌與半棘肌的ATGL表現顯著高於股直肌(P<0.05),但在兩者間沒有顯著差異。洋種豬股直肌之ATGL、H-FABP及CPT1b顯著地低於背最長肌與半棘肌(P<0.05),而背最長肌與半棘肌之間則無顯著差異;背最長肌之FAS表現顯著高於其半棘肌及股直肌(P<0.05),但在半棘肌及股直肌兩者間則無差異,而SREBP1c的表現以背最長肌為最高,半棘肌次之,股直肌為最低(P<0.05);Leptin基因在股直肌的表現量高於半棘肌及背最長肌(P<0.05),但於半棘肌及背最長肌則無差異。民間黑豬之SREBP1c表現在股直肌中為最高(P<0.05),而在其背最長肌與半棘肌中則有相似的表現;半棘肌之H-FABP表現顯著高於背最長肌及股直肌(P<0.05),其在背最長肌與股直肌之間沒有差異;背最長肌之ATGL表現顯著高於半棘肌(P<0.05),但在其餘肌肉之間則無顯著差異。 綜上所述,高畜黑豬與民間黑豬在背最長肌、肩胛及後腿之肌內脂肪累積潛力高於洋種豬,而此三豬種之背最長肌與肩胛之肌內脂肪累積潛能應高於後腿。為確認表型與基因表現之間的關係,則需要更多資訊,如一般成分分析、肉質性狀分析等。

並列摘要


Intramuscular fat (IMF) affects meat quality, especially juiciness, tenderness and flavor. The content of IMF are various in different types of muscle. Previous literature indicated that IMF content in M. longissimus muscle was higher in Kaohsiung Animal Propagation Station Black Pigs (KHAPS Black pigs) than in exotic pigs. However, the study in pig meat quality and phenotype of gene expression always focused on the longissimus muscle. Therefore, the objective of this study was to investigate the expression levels of lipid metabolism-related genes in different types of muscle among breeds. The study collected muscle samples from M. Longissimus Dorsi (MLD) between the 10th and 11th ribs, shoulder (M. Semispinalis Capitis, MSC) and ham (M. Rectus Femoris, MRF) of 14 KHAPS Black Pigs (K), 14 exotic pigs (E, seven Duroc and seven Landrace pigs) and 16 black pigs (B). Real-time PCR was used to quantitate mRNA expressions of the lipid metabolism-related gene, including ATGL, SCD, HSL, LDLR, SREBP1c, CPT1b, FAS, Leptin and H-FABP genes. FAS is a key enzyme in fatty acid synthesis, and SREBP1c is the principal regulatory transcription factor for fatty acid synthesis in mammals. H-FABP is critical for fatty acid uptake as well as intracellular trafficking in muscles. Our results showed that the expression levels of SREBP1c and H-FABP in E pigs were the lowest of all (P<0.05), and were similar in K/B. However, the expression level of FAS was significantly higher in MSC of K than E (P<0.05) , which suggested that the lipid synthesis and fatty acid transportation were higher in K and B compared with E, indicated the MSC of K expected more fatty acid synthesis than E pigs. ATGL is present in all cell types that can start initial step in lipid hydrolysis. Unlike HSL, ATGL shows strong preference for triacylglycerol as substrate. In skeletal muscle, Leptin played a major role in anti-obesity by directly affecting glucose and fatty acid metabolism.The expression levels of ATGL and Leptin in E pigs were the highest of all (P<0.05),and were similar in K/B. In KHAPS Black Pigs, the expression levels of H-FABP, FAS, and SREBP1c were the lowest in MRF (P<0.05); but there were no significant difference between MLD and MSC. ATGL was significantly higher in MLD than in MSC (P<0.05); but there were no significant difference between MSC and MRF. In exotic pigs, the expression levels of ATGL, H-FABP and CPT1b in MRF were the lowest of all (P<0.05), and were similar in MLD/MSC. FAS in MLD was the highest of all (P<0.05), and there were similar in MSC/MRF. The expression levels of SREBP1c were in following order: MLD, MRF and MSC; MLD was the highest (P<0.05). Leptin was the highest in MRF (P<0.05), but not significantly difference between MLD and MSC. In black pigs, MRF showed the highest expression levels of SREBP1c (P<0.05), but was similar in MLD and MSC. The expression levels of H-FABP in MRF was the lowest of all (P<0.05), but there were no significant difference between MLD and MSC. ATGL was significantly higher in MLD than in MSC (P<0.05), but there were not significantly difference between MSC and MRF. In conclusion, high potential of IMF accumulation could be expected in loin,shoulder and ham in K and B than in comparison of the expressions of lipid metabolism-related genes to exotic pigs. However, We need more information like carcass trait to analysis the association between phenotype and mRNA expressions.

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