| This dissertation is a summary of work done in the study of Drosophila neurophysiology. This endeavor primarily involves direct observation of channel activity using electrophysiological techniques. In third instar larvae, a live preparation was devised to characterize motorneurons in situ. By recording from ion channels in their natural milieu, a comprehensive, functional account of five individually identified motorneurons (MN6/7-Ib, MN1-Ib, MN14-Ib, MN 30-Ib and MNISN-Is) was obtained using electrophysiology in combination with labeling, pharmacology and biophysical methods. A fast-inactivating, voltage-sensitive potassium channel (Shal) was shown to mediate the delayed spiking response to current pulse. Next, transgenic overexpression of a leak potassium channel (Shaw) in full-length and truncated form was studied in the MNISN-Is neuron. The truncated overexpression altered the whole cell parameters as recorded from the soma, such that the presumed dominant-negative block of leak current depolarized the cell while decreasing input resistance. Also, the direct target and plausible mechanism of therapeutic effect of a common anticonvulsant drug (carbamazepine) was explored using the Drosophila as a model system, and it was found that an effect on fly sleep behavior was evoked via the Rdl channel. The cumulative result of this dissertation is, in effect, a showcasing of how multiple aspects of ion channel neurophysiology can be studied in Drosophila by incorporating electrophysiological techniques. |
