Acetylcholinesterase genes in the basal Hexapod Orchesella villosa


Francesco Nardi, Department of Evolutionary Biology, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy. Tel.:+39 0577 234420; fax: +39 0577 234476; E-mail:


Acetylcholinesterase (AChE) is a key enzyme of the cholinergic nerve system. Of the two forms found in insects, the predominant one is active in the synapses and is the target of organophosphate and carbamate insecticides, while the role of the second is currently unknown. Two acetylcholinesterase cDNAs from the basal hexapod Orchesella villosa have been characterized and compared with others reported form insects. One form conforms well to the typical structure, while the other is characterized by an unusual 3′ region. No amino acid mutation could be directly associated with known resistance mutations in other insect species or to a clear signal of selection in the distribution of alleles, although the action of some population process is suggested.