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Calcium Imaging of Odor-evoked Responses in the Drosophila Antennal Lobe
Published on: March 14, 2012
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Chemoreceptor co-expression in Drosophila melanogaster olfactory neurons
Darya Task1, Chun-Chieh Lin1,2, Alina Vulpe3
1The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States.
Elife
|April 20, 2022
Summary
Fruit fly olfactory neurons co-express multiple chemosensory receptor families, challenging previous assumptions. This widespread co-expression, including odorant receptors (ORs) and ionotropic receptors (IRs), is conserved across insect species.
Area of Science:
- Neuroscience
- Genetics
- Insect Olfaction
Background:
- Olfactory neurons in *Drosophila melanogaster* were traditionally believed to express only one chemosensory receptor gene family.
- Two primary olfactory receptor families exist: odorant receptors (ORs) and ionotropic receptors (IRs).
- Functional ORs and IRs require co-receptor genes: *Orco* for ORs, and *Ir25a*, *Ir8a*, *Ir76b* for IRs.
Purpose of the Study:
- To investigate the expression patterns of four key chemosensory co-receptors (*Orco, Ir8a, Ir76b, Ir25a*) in *Drosophila melanogaster*.
- To determine the extent of co-expression among these co-receptors in olfactory sensory neurons.
- To examine the conservation of co-receptor co-expression in other insect species.
Main Methods:
- Utilized a novel genetic knock-in strategy to target and analyze the expression of *Orco, Ir8a, Ir76b,* and *Ir25a*.
- Verified knock-in expression patterns against endogenous expression.
- Performed single sensillum recordings in mutant and wild-type flies to assess olfactory responses.
Main Results:
- Discovered extensive overlap in the expression patterns of the four co-receptors, indicating widespread co-expression.
- *Ir25a* is broadly expressed in 88% of olfactory sensory neuron classes and co-expressed in 82% of *Orco*+ neuron classes.
- Observed co-expression of *Orco* and *Ir25a* in *Drosophila sechellia* and *Anopheles coluzzii*, suggesting evolutionary conservation.
Conclusions:
- The expression patterns of *Orco, Ir8a,* and *Ir76b* are more expansive than previously understood.
- Co-expression of chemosensory receptor co-receptors is a common feature of insect olfactory neurons.
- This study provides the first comprehensive map of chemosensory co-receptor expression in *Drosophila*, revealing unexpected widespread co-expression.
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