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Measurement of Carbon Dioxide Production from Radiolabeled Substrates in Drosophila melanogaster
Published on: June 27, 2016
Drosophila tracks carbon dioxide in flight
Sara Wasserman1, Alexandra Salomon, Mark A Frye
1Department of Integrative Biology and Physiology, Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
Current Biology : CB
|January 29, 2013
Summary
Fruit flies actively track carbon dioxide (CO(2)) plumes in flight, contrary to their walking aversion. This flight-based attraction involves a novel olfactory pathway, the olfactory coreceptor (Orco), and octopamine signaling.
Area of Science:
- Neuroscience
- Olfactory Signaling
- Insect Behavior
Background:
- Carbon dioxide (CO(2)) is a host-seeking attractant for mosquitoes but typically aversive to Drosophila melanogaster.
- Previous studies on fly CO(2) responses were limited to walking behavior, neglecting airborne cues.
- Adult flies track distant food sources using flight, suggesting a need to study CO(2) responses in this context.
Purpose of the Study:
- To investigate whether Drosophila melanogaster exhibits CO(2) attraction during flight.
- To identify the olfactory mechanisms and neural pathways involved in flight-based CO(2) tracking.
- To understand how behavioral state (walking vs. flight) influences the valence of CO(2) stimuli.
Main Methods:
- Utilized a tethered flight simulator allowing free rotation in a magnetic field to assess behavioral responses to CO(2) plumes.
- Employed genetic manipulations, including disruption of canonical CO(2)-sensing neurons, antennal ablation, Ir64a sensor disruption, olfactory coreceptor (Orco) mutation, and octopamine neuron manipulation.
- Compared CO(2) responses in walking versus flying flies under various genetic conditions.
Main Results:
- Tethered flying flies actively tracked narrow CO(2) plumes.
- In-flight CO(2) attraction was independent of canonical CO(2)-sensing neurons but dependent on antennal input, Ir64a, and the olfactory coreceptor (Orco).
- While Orco mutation did not affect walking aversion to CO(2), it abolished flight tracking; octopamine neuron inhibition inverted CO(2) valence in flight.
Conclusions:
- A novel olfactory pathway, mediated by Orco and Ir64a, confers CO(2) sensitivity during flight.
- The biogenic amine octopamine plays a crucial role in modulating CO(2) valence during flight.
- These findings reveal a behavioral-state-dependent switch in CO(2) stimulus valence, mediated by a dynamic olfactory circuit.
