title: Production of null mutants in the major intestinal esterase gene (ges-1) of the nematode Caenorhabditis elegans.
abstract: 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.
authors.affiliation: Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
authors.forename: J D
authors.initials: JD
authors.lastname: McGhee
authors.forename: J C
authors.initials: JC
authors.lastname: Birchall
authors.forename: M A
authors.initials: MA
authors.lastname: Chung
authors.forename: D A
authors.initials: DA
authors.lastname: Cottrell
authors.forename: L G
authors.initials: LG
authors.lastname: Edgar
authors.forename: P C
authors.initials: PC
authors.lastname: Svendsen
authors.forename: D C
authors.initials: DC
authors.lastname: Ferrari
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002107:Caenorhabditis / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D004950:Esterases / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005796:Genes; D007422:Intestines / Q000201:enzymology; D008297:Male; D009154:Mutation
chemical_list: D004950:Esterases