McGhee J D, Birchall J C, Chung M A, Cottrell D A, Edgar L G, Svendsen P C, Ferrari D C
Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
Genetics. 1990 Jul;125(3):505-14. doi: 10.1093/genetics/125.3.505.
The ges-1 gene of the nematode Caenorhabditis elegans codes for a nonspecific carboxylesterase that is expressed only in the intestinal lineage. This esterase has turned out to be a convenient biochemical marker for lineage-specific differentiation. In the present paper, we describe the production of several C. elegans strains that lack detectable activity of the ges-1 esterase. To isolate these ges-1 null strains, we first produced a strain of hermaphrodites in which the wild-type copy of the ges-1 gene was stably balanced over a previously isolated isoelectric focusing allele, ges-1(ca6); this parental strain was then mutagenized with EMS and isoelectric focusing gels were used to identify progeny populations that lacked either ges-1(+) or ges-1(ca6) esterase activity. This method is a straightforward and general approach to obtaining null mutations in any gene that has a biochemical or immunological assay. The ges-1 gene is not essential to worm survival, development or reproduction. Furthermore, lack of the ges-1 product has no obvious effect on the ability of worms (containing either normal or greatly reduced levels of acetylcholinesterases) to survive exposure to esterase inhibitors. The ges-1 gene product provides roughly half of the total esterase activity measured in crude extracts of L1 larvae or mixed worm populations. However, histochemical staining of individual ges-1(0) embryos shows that the ges-1 esterase is the first and essentially the only esterase to be produced during embryonic development, from the midproliferation phase up to at least the twofold stage of morphogenesis. These ges-1(0) strains now allow us to investigate the developmental control of the ges-1 gene by DNA-mediated transformation, in which the ges-1 gene acts as its own reporter.
线虫秀丽隐杆线虫的ges-1基因编码一种非特异性羧酸酯酶，该酶仅在肠道谱系中表达。事实证明，这种酯酶是谱系特异性分化的一种方便的生化标记。在本文中，我们描述了几种缺乏可检测到的ges-1酯酶活性的秀丽隐杆线虫菌株的产生。为了分离这些ges-1基因缺失菌株，我们首先构建了一个雌雄同体菌株，其中ges-1基因的野生型拷贝在先前分离的等电聚焦等位基因ges-1(ca6)上稳定平衡；然后用EMS对该亲本菌株进行诱变，并使用等电聚焦凝胶来鉴定缺乏ges-1(+)或ges-1(ca6)酯酶活性的子代群体。这种方法是在任何具有生化或免疫分析的基因中获得基因缺失突变的一种直接且通用的方法。ges-1基因对于线虫的生存、发育或繁殖并非必需。此外，缺乏ges-1产物对线虫（含有正常水平或大大降低水平的乙酰胆碱酯酶）在接触酯酶抑制剂时的存活能力没有明显影响。ges-1基因产物提供了L1幼虫粗提物或混合线虫群体中测得的总酯酶活性的大约一半。然而，对单个ges-1(0)胚胎的组织化学染色表明，ges-1酯酶是胚胎发育过程中从增殖中期到至少形态发生两倍阶段产生的第一种且基本上是唯一的酯酶。这些ges-1(0)菌株现在使我们能够通过DNA介导的转化来研究ges-1基因的发育调控，其中ges-1基因充当其自身的报告基因。
