Conduction in the Giant Nerve Fiber Pathway in Temperature-Sensitive Paralytic Mutants of Drosophila

Abstract

To study electrogenic conduction in neurons of the cervical giant nerve fiber (CGF) pathway in Drosophiia adults carrying temperature –sensitive paralytic mutations that affect sodium channels, we recorded dorsal longitudinal muscle (DLM) responses evoked by electrical stimulation of the brain. In the mutants tipE, nap^ts and para^ts, conduction in certain neurons presynaptic to the CGF failed at about the same temperature at which paralysis occurred in each mutant. Conduction in the CGF and neurons postsynaptic to it remained active in all mutants even at very elevated temperatures. In contrast, analysis of sei mutants showed enhanced spontaneous activity at elevated temperatures in at least some neurons of the CGF pathway. The implications of these results with respect to the normal in vivo functions of these genes in neuronal signalling are considered.

Key Words:

• sodium channels
• membrane excitability
• action potentials
• cervical giant fiber pathway