黒毛和種におけるDGAT1遺伝子多型の枝肉形質に対する効果  [in Japanese] Association of DGAT1 K232A polymorphisms with beef carcass traits in Japanese Black cattle  [in Japanese]

Diacylglycerol O-acyltransferase 1 (<I>DGAT1</I>）は筋内脂肪の主成分であるトリグリセリド合成の最終経路に関わっている．本研究ではウシ<I>DGAT1</I>遺伝子と枝肉形質との関連について調査するため翻訳領域における多型探索を行い，検出された非同義置換（K232A）に対し2つの黒毛和種集団，各438頭および245頭を用いて解析を行った．PCR-RFLP法により<I>DGAT1</I> K232Aの遺伝子型判定を行い，統計学的手法を用いて遺伝子型の各形質に対する効果を調査した．分散分析の結果，いずれの集団においても皮下脂肪厚に対しK232Aの効果が認められ，TukeyのHSD検定の結果，<I>K</I>対立遺伝子を持つ個体で皮下脂肪厚値が有意に低くなっていることが示された（<I>P</I> ＜ 0.05）．このことから<I>DGAT1</I> K232Aは枝肉形質の改良に際し有用なDNAマーカーとなることが示唆された．

Genes associated with fat metabolism have the potential to influence beef traits including fat deposition and fatty acid composition. Diacylglycerol O-acyltransferase 1 (<I>DGAT1</I>) encodes the enzyme acyl-CoA diacylglycerol-acyltransferase that plays a fundamental role in the metabolism of cellular diacylglycerol in physiological processes and catalyzes the final step in the synthesis of triglyceride. In this study, we investigated polymorphisms in full length coding sequence of <I>DGAT1</I> and its association with the beef carcass traits. Sequence comparison of eight animals including four Japanese Black and four Holstein cattle revealed a nonsynonymous substitution, K232A in <I>DGAT1.</I> We investigated association between the genotype and carcass traits in two Japanese Black cattle populations (N = 438, 245). The effect of genotype was observed on subcutaneous fat thickness by analysis of variance (<I>P</I> < 0.05). Animals with <I>DGAT1 K/K</I> type indicated 0.29 point lower value in subcutaneous fat thickness than that with <I>A/A</I> type (<I>P</I> < 0.05). This result indicated that the polymorphism of <I>DGAT1</I> K232A could be one of responsible genetic factors for subcutaneous fat thickness in Japanese Black cattle. This finding has important implication for production of high grade meat in beef cattle.