Cloning and sequencing of inebriated, a gene encoding a neurotransmitter transporter in Drosophila melanogaster

Abstract

Behavioral and electrophysiological studies on mutants defective in the Drosophila inebriated (ine) gene demonstrated increased excitability of the motor neuron. In this thesis is described the cloning and sequence analysis of ine. Mutations in ine were localized on cloned DNA by restriction fragment-length polymorphism (RFLP) mapping of ine mutants. DNA from the ine region was then used to isolate an ine cDNA. In the course of screening for ine cDNAs, other genes of interest were isolated from the ine genetic region and were further characterized. The ine cDNA contains an open reading frame of 658 amino acids with a high degree of sequence similarity to members of the Na\sp+/Cl\sp--dependent neurotransmitter transporter family. Members of this family catalyze the rapid re-uptake of neurotransmitters released into the synapse, and thereby play key roles in controlling neuronal function. The conclusion is that ine mutations cause increased excitability of the Drosophila motor neuron by causing the defective re-uptake of the substrate neurotransmitter ine transporter, and thus over stimulation of the motor neuron by this neurotransmitter. From this observation comes a unique opportunity to perform a genetic dissection of the regulation of excitability of the Drosophila motor neuron