Hastings I M, Hill W G
Institute of Animal Genetics, University of Edinburgh.
Genet Res. 1990 Feb;55(1):55-61. doi: 10.1017/s0016672300025192.
Estimates of the activities (Vmax) of six enzymes involved in de novo fat synthesis were made in replicated lines of mice differing in fat content. These lines had been selected high and low for 20 generations with three replicates each of Fat, Control and Lean lines and for a further eight generations high and low as an unreplicated line. The activities of ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACC), fatty acid synthetase (FAS), cytoplasmic malate dehydrogenase (MDH), malic enzyme (ME) and pyruvate kinase (PK) were determined in vitro in both liver and gonadal fatpad tissues taken at ages five and ten weeks. The activities of ACL, ACC, FAS and ME were significantly higher in the Fat than the Lean lines, and the differences were more pronounced at the earlier age and in the gonadal fatpad where activities in the Fat lines were higher by factors of 3.5, 2.4, 2.5 and 3.5 respectively. The activity of PK was unchanged in each tissue. MDH activity was significantly lower in adipose tissue in the Fat lines than the Lean lines at age ten weeks but not at age five weeks or in liver tissue. Results from replicates indicated that random genetic drift affected enzyme activities but nevertheless significant changes in activity were associated with the direction of selection. The changes in enzyme activity reported here are similar to those known to be associated with major mutations causing obesity in mice.
对脂肪含量不同的小鼠复制品系中参与从头脂肪合成的六种酶的活性（Vmax）进行了估算。这些品系已在高脂肪、对照和低脂肪品系中分别进行了20代的高选和低选，每个品系有三个重复，之后又作为非重复品系进行了另外八代的高选和低选。在五周龄和十周龄时采集的肝脏和性腺脂肪垫组织中，体外测定了ATP - 柠檬酸裂解酶（ACL）、乙酰辅酶A羧化酶（ACC）、脂肪酸合成酶（FAS）、细胞质苹果酸脱氢酶（MDH）、苹果酸酶（ME）和丙酮酸激酶（PK）的活性。在高脂肪品系中，ACL、ACC、FAS和ME的活性显著高于低脂肪品系，且差异在较早年龄以及性腺脂肪垫中更为明显，在性腺脂肪垫中，高脂肪品系的活性分别高出3.5、2.4、2.5和3.5倍。PK的活性在每个组织中均未改变。在十周龄时，高脂肪品系脂肪组织中的MDH活性显著低于低脂肪品系，但在五周龄时或肝脏组织中并非如此。重复实验的结果表明，随机遗传漂变影响酶的活性，但活性的显著变化仍与选择方向相关。此处报道的酶活性变化与已知的与导致小鼠肥胖的主要突变相关的变化相似。
