Cross references: Amphioxus Neurotransmitters Acetylcholine
Acetylcholine Gate Acetylcholine Metabotropic Receptor
Searching for "amphioxus acetylcholine" yielded:
PubMed = 4 http://www.ncbi.nlm.nih.gov/pubmed/?term=amphioxus+acetylcholine
Google = 149,000 https://www.google.com/search?q=amphioxus+acetylcholine&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=np&source=hp
Evolution of cholinesterases in the animal kingdom.
The cholinergic gene locus in amphioxus: molecular characterization and developmental expression patterns.
Google:cDNA cloning, in vitro expression, and biochemical characterization of cholinesterase 1 and cholinesterase 2 from amphioxus
The first page of Google hits found:
Acetylcholinesterases from Amphioxus
The second page of Google hits found:
Two cholinesterase activities and genes are present in amphioxus
The third and fourth pages of Google hits did not find any new, useful references.
From: Amphioxus Neurotransmitters .
The nervous system of amphioxus: structure, development, and evolutionary significance
A 29 page PDF with more than a dozen diagrams. I've cited it on many other pages.
The title, above, is an active link.
"... The synaptic zones in each segment consist of two distinct domains, the ventral and dorsal synaptic compartments. Both utilize acetylcholine as a transmitter. The ventral synaptic compartments are where the deep, anaerobic, fast muscle cells receive their innervation. The dorsal compartment is where the superficial, aerobic, slow muscle cells of the myomeres receive their innervation."
So far, these are the only synapses in the amphioxus for which specific neurotransmitters have been identified. "Both use Acetylcholine ".
The cholinergic gene locus in amphioxus: molecular characterization and developmental expression patterns(PubMed)
Also discussed in Ventral Motor Neurons and Dorsal Motor Neurons.
"Here, we report the cloning, sequences, and embryonic expression of the amphioxus homologs of two alternatively spliced transcripts of the cholinergic gene locus (CGL)".
"The CGL arose early in metazoan evolution and persists in the vertebrates, indicating its importance as a functional unit in the genome and the selective advantage it must confer"
"Our analysis confirms that the genomic organization of the amphioxus CGL is similar to that reported from other vertebrate and invertebrate species."
"In chordates, cholinergic transmission is typically a characteristic of motoneurons"
" ... CGL-expressing cells contain a mixture of motoneurons and interneurons... the implication is that a substantial proportion of the cells of the locomotory control circuit, both interneurons and motoneurons, may all be using the same transmitter."
"In fact, it would be very surprising if the motoneurons were not cholinergic based on what we know of other chordates ... but it is also clear that there could be other classes of cholinergic neurons in the nerve cord."
" In this context, it is worth pointing out that the photoreceptor cells of the larval ocellus, which also express CGL genes, are known to have DC motoneurons as their principal synaptic targets "