Voltage-activated and odor-modulated conductances in olfactory neurons of Drosophila melanogaster.
Voltage-activated currents and odor-modulated conductances were studied in cells in semi-intact Drosophila third antennal segments (the main olfactory organ) using patch-clamp techniques. All neurons expressed outward currents, and most expressed labile fast transient inward currents with kinetics similar to Na+ currents in other systems. Action potentials were detected as bipolar capacitative current transients in cell-attached or loose patches from the soma of both odor-sensitive (97%) and insensitive neurons. A mixture of odorants from five chemical classes caused an increase (approximately 70%), decrease (approximately 10%), or no effect on firing frequency in pharate adult neurons. The development of chemosensitivity was examined and odor-induced changes in action potential firing frequency were recorded in pupal antennal neurons as early as P8, a stage after completion of sensillar development. The character of odor-induced responses was more profound and complex later in development; small, tonic increases in firing frequency were observed at pupal stages P8 through P11 (ii), while in older pupae and young adults approximately 25% of the increased responses were phasic-tonic. The apical dendrite was the site of odor modulation in approximately 90% and 100% of responsive adult and early pupal neurons, respectively. Whole-cell recordings revealed that apparent nonselective cation and chloride conductances were modulated by a mixture of odorants in separate antennal neurons.
Dubin
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AE
Department of Biology, San Diego State University, California 92182-4614, USA. adubin@sunstroke.sdsu.edu
Harris
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GL
D000367:Age Factors; D000818:Animals; D004331:Drosophila melanogaster / Q000502:physiology*; D004553:Electric Conductivity; D015640:Ion Channel Gating / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D009812:Odorants; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011679:Pupa / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology