Saini K S, Byrne C R, Leish Z, Pruss C A, Rigby N W, Brownlee A G, Nancarrow C D, Ward K A
CSIRO Division of Animal Production, Prospect, NSW, Australia.
Transgenic Res. 1996 Nov;5(6):467-73. doi: 10.1007/BF01980212.
The glyoxylate cycle, catalysed by two unique enzymes: isocitrate lyase (ICL; EC 4.1.3.1) and malate synthase (MS; EC 4.1.3.2), is necessary for the net conversion of acetate into glucose. This metabolic pathway operates in microorganisms, higher plants and nematodes. Two bacterial genes, encoding ICL and MS, were modified in order to introduce them into the mouse germ line. The ovine metallothionein-Ia (MT-Ia) promoter-ace B gene-ovine growth hormone (GH) gene (3' GH sequence) construct was fused to the ovine, MT-Ia promoter-ace A gene-ovine GH gene (3' GH sequence). Therefore, in this single DNA sequence, both ace A and ace B are under independent MT-Ia promoter control and can be induced by zinc. Transgenic mice were generated by pronuclear microinjection of the ace B-ace A gene construct. We now report the establishment of four mouse lines carying these two transgenes. Studies on the progeny of these lines indicate that one line (No. 91) is expressing both genes at the mRNA and enzyme levels in the liver and intestine, whereas another line (No. 66) has a much lower expression. Both enzyme activities were detected in the liver and intestine at levels up to 25% of those measured in fully derepressed Escherichia coli cells.
异柠檬酸裂解酶（ICL；EC 4.1.3.1）和苹果酸合酶（MS；EC 4.1.3.2），它对于将乙酸净转化为葡萄糖是必需的。这条代谢途径在微生物、高等植物和线虫中发挥作用。为了将两个编码ICL和MS的细菌基因引入小鼠种系，对它们进行了改造。将绵羊金属硫蛋白-Ia（MT-Ia）启动子-ace B基因-绵羊生长激素（GH）基因（3' GH序列）构建体与绵羊MT-Ia启动子-ace A基因-绵羊GH基因（3' GH序列）融合。因此，在这个单一的DNA序列中，ace A和ace B都处于独立的MT-Ia启动子控制之下，并且可以被锌诱导。通过对ace B-ace A基因构建体进行原核显微注射产生了转基因小鼠。我们现在报告建立了四个携带这两个转基因的小鼠品系。对这些品系后代的研究表明，一个品系（91号）在肝脏和肠道中mRNA和酶水平上都表达这两个基因，而另一个品系（66号）的表达水平则低得多。在肝脏和肠道中检测到的两种酶活性水平高达完全去阻遏的大肠杆菌细胞中所测水平的25%。
