The cholinergic gene locus in amphioxus: molecular characterization and developmental expression patterns.

Area of Science:

• Neuroscience
• Developmental Biology
• Evolutionary Biology

Background:

• The cholinergic gene locus (CGL) encodes vesicular acetylcholine transporter (VAChT) and choline acetyltransferase (ChAT), key markers for cholinergic neurons.
• Studying these genes in basal chordates like amphioxus can illuminate the evolution of cholinergic systems.

Purpose of the Study:

• To isolate and characterize amphioxus homologs of VAChT and ChAT.
• To investigate the developmental expression patterns of VAChT and ChAT in amphioxus.
• To explore the evolutionary conservation of VAChT/ChAT mRNA splicing.

Main Methods:

• Isolation of amphioxus VAChT and ChAT genes.
• Analysis of the 5' untranslated regions for conserved splicing.
• Double whole-mount in situ hybridization to examine gene coexpression during development.

Main Results:

• Amphioxus VAChT and ChAT genes were isolated and their developmental expression examined.
• Analysis suggests conserved mRNA splicing of VAChT/ChAT between amphioxus and mammals.
• VAChT and ChAT are coexpressed in the same cells, initially in the neural plate and later in the anterior nerve cord, including motoneurons, interneurons, and ocellus receptor cells.

Conclusions:

• VAChT and ChAT are coexpressed in specific neuronal populations during amphioxus development.
• The findings support evolutionary conservation of cholinergic gene expression and splicing mechanisms.
• This study provides insights into the early evolution of the cholinergic nervous system.