Acetylcholinesterase (AChE) is a major neurotransmitter in the nervous system that has also been identified in embryos where its function remains unclear. In 2 January online Nature Neuroscience, Martine Behra and colleagues from Institut de Génétique et de Biologie Moléculaire et Cellulaire, Strasbourg, France show that ACh is required for neuronal and muscular development in the zebrafish embryo.

Behra et al. observed that a homozygous, nonfunctional AChE allele cause defects in muscle fiber formation and innervation in zebrafish embryos. The neuromuscular phenotype in these mutants is suppressed when the nicotinic acetylcholine receptor (nAChR) is impaired, indicating that the defect of neuromuscular development is mediated by activation of nAChR in the mutant embryo (Nat Neurosci 2002, DOI 10.1038/nn788).

These results provide genetic evidence that AChE activity is required for the correct development of the muscle apparatus and show the non-classical functions of AChE in vertebrate development.