Multiple ace genes encoding acetylcholinesterases of Caenorhabditis elegans have distinct tissue expression.
ace-1 and ace-2 genes encoding acetylcholinesterase in the nematode Caenorhabditis elegans present 35% identity in coding sequences but no homology in noncoding regions (introns, 5'- and 3'-untranslated regions). A 5'-region of ace-2 was defined by rescue of ace-1;ace-2 mutants. When green fluorescent protein (GFP) expression was driven by this regulatory region, the resulting pattern was distinct from that of ace-1. This latter gene is expressed in all body-wall and vulval muscle cells (Culetto et al., 1999), whereas ace-2 is expressed almost exclusively in neurons. ace-3 and ace-4 genes are located in close proximity on chromosome II (Combes et al., 2000). These two genes were first transcribed in vivo as a bicistronic messenger and thus constitute an ace-3;ace-4 operon. However, there was a very low level of monocistronic mRNA of ace-4 (the upstream gene) in vivo, and no ACE-4 enzymatic activity was ever detected. GFP expression driven by a 5' upstream region of the ace-3;ace-4 operon was detected in several muscle cells of the pharynx (pm3, pm4, pm5 and pm7) and in the two canal associated neurons (CAN cells). A dorsal row of body-wall muscle cells was intensively labelled in larval stages but no longer detected in adults. The distinct tissue-specific expression of ace-1, ace-2 and ace-3 (coexpressed only in pm5 cells) indicates that ace genes are not redundant.
Combes
Didier
D
Différenciation cellulaire et croissance, INRA, 2 place Viala, 34060 Montpellier cedex 1, France.
Fedon
Yann
Y
Toutant
Jean-Pierre
JP
Arpagaus
Martine
M
D000110:Acetylcholinesterase / Q000235:genetics*; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D016678:Genome; D007527:Isoenzymes / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic
D007527:Isoenzymes; D012333:RNA, Messenger; D000110:Acetylcholinesterase