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Re-Classification of Drosophila melanogaster Trichoid and Intermediate Sensilla Using Fluorescence-Guided Single Sensillum Recording.

Lin CC, Potter CJ - PLoS ONE (2015)

Bottom Line: Drosophila olfactory receptor neurons are found within specialized sensory hairs on antenna and maxillary palps.Fluorescence-guided SSR further revealed that two antennal trichoid sensilla types should be re-classified as intermediate sensilla.This approach provides a simple and practical addition to a proven method for investigating olfactory neurons, and can be extended by the addition of UAS-geneX effectors for gain-of-function or loss-of-function studies.

View Article: PubMed Central - PubMed

Affiliation: The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.

ABSTRACT
Drosophila olfactory receptor neurons are found within specialized sensory hairs on antenna and maxillary palps. The linking of odorant-induced responses to olfactory neuron activities is often accomplished via Single Sensillum Recordings (SSR), in which an electrode inserted into a single sensory hair records the neuronal activities of all the neurons housed in that sensillum. The identification of the recorded sensillum requires matching the neuronal responses with known odor-response profiles. To record from specific sensilla, or to systematically screen all sensillar types, requires repetitive and semi-random SSR experiments. Here, we validate an approach in which the GAL4/UAS binary expression system is used for targeting specific sensilla for recordings. We take advantage of available OrX-Gal4 lines, in combination with recently generated strong membrane targeted GFP reporters, to guide electrophysiological recordings to GFP-labeled sensilla. We validate a full set of reagents that can be used to rapidly screen the odor-response profiles of all basiconic, intermediate, and trichoid sensilla. Fluorescence-guided SSR further revealed that two antennal trichoid sensilla types should be re-classified as intermediate sensilla. This approach provides a simple and practical addition to a proven method for investigating olfactory neurons, and can be extended by the addition of UAS-geneX effectors for gain-of-function or loss-of-function studies.

No MeSH data available.


Flow chart comparing traditional SSR with Fluorescence-guided SSR.Traditional Single Sensillum Recordings (SSR) often requires screening many sensilla for odorant activities before identifying a correct target. Fluorescence-guided SSR (FgSSR) allows for GFP-labeled sensilla to be targeted directly for recordings. This increases the success rate for recording from a specific sensillum (e.g., ab4), and decreases the effort needed to record from the desired sensillum. FgSSR is also useful for targeting sparse sensilla (e.g. ab4 to ab10), sensilla with similar sizes and locations (ab6-10 with ai1-3; pb1-3), sensilla that house neurons with unknown odor-responses (e.g, ai1), or for targeting specific Odorant Receptors in unknown sensillar types. Thick “Yes/No” arrows indicate higher probabilities and thin decision arrows indicate lower probabilities.
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pone.0139675.g001: Flow chart comparing traditional SSR with Fluorescence-guided SSR.Traditional Single Sensillum Recordings (SSR) often requires screening many sensilla for odorant activities before identifying a correct target. Fluorescence-guided SSR (FgSSR) allows for GFP-labeled sensilla to be targeted directly for recordings. This increases the success rate for recording from a specific sensillum (e.g., ab4), and decreases the effort needed to record from the desired sensillum. FgSSR is also useful for targeting sparse sensilla (e.g. ab4 to ab10), sensilla with similar sizes and locations (ab6-10 with ai1-3; pb1-3), sensilla that house neurons with unknown odor-responses (e.g, ai1), or for targeting specific Odorant Receptors in unknown sensillar types. Thick “Yes/No” arrows indicate higher probabilities and thin decision arrows indicate lower probabilities.

Mentions: Given the diversity of sensillar types (19 types in antenna and 3 types in maxillary palps), identification of each target sensilla for measurement of olfactory responses can be challenging and time-consuming (Fig 1). One method to circumvent this is to use the GAL4/UAS binary expression system [8, 9] to mis-express individual ORs in an easily identified basiconic sensilla (ab3) that houses a neuron lacking its endogenous receptor (the empty neuron system, genotype: Δhalo/Δhalo; Or22a-Gal4/UAS-OrX; [10]). This has proved to be an extremely powerful approach to define the odor profiles of many ORs [6, 7, 11]. However, several odorant receptors do not function in the empty neuron system (e.g, pheromone receptors, [12]), possibly because essential factors are lacking in the ab3A neuron or absent in the lymph surrounding the neuron [13, 14]. Therefore, direct measurement of neuronal activities in native sensilla remains the most reliable way to characterize the odor-activation profiles of individual ORNs. However, this can be particularly challenging for olfactory neurons that are sparse, or if odor-properties are not well defined.


Re-Classification of Drosophila melanogaster Trichoid and Intermediate Sensilla Using Fluorescence-Guided Single Sensillum Recording.

Lin CC, Potter CJ - PLoS ONE (2015)

Flow chart comparing traditional SSR with Fluorescence-guided SSR.Traditional Single Sensillum Recordings (SSR) often requires screening many sensilla for odorant activities before identifying a correct target. Fluorescence-guided SSR (FgSSR) allows for GFP-labeled sensilla to be targeted directly for recordings. This increases the success rate for recording from a specific sensillum (e.g., ab4), and decreases the effort needed to record from the desired sensillum. FgSSR is also useful for targeting sparse sensilla (e.g. ab4 to ab10), sensilla with similar sizes and locations (ab6-10 with ai1-3; pb1-3), sensilla that house neurons with unknown odor-responses (e.g, ai1), or for targeting specific Odorant Receptors in unknown sensillar types. Thick “Yes/No” arrows indicate higher probabilities and thin decision arrows indicate lower probabilities.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4592000&req=5

pone.0139675.g001: Flow chart comparing traditional SSR with Fluorescence-guided SSR.Traditional Single Sensillum Recordings (SSR) often requires screening many sensilla for odorant activities before identifying a correct target. Fluorescence-guided SSR (FgSSR) allows for GFP-labeled sensilla to be targeted directly for recordings. This increases the success rate for recording from a specific sensillum (e.g., ab4), and decreases the effort needed to record from the desired sensillum. FgSSR is also useful for targeting sparse sensilla (e.g. ab4 to ab10), sensilla with similar sizes and locations (ab6-10 with ai1-3; pb1-3), sensilla that house neurons with unknown odor-responses (e.g, ai1), or for targeting specific Odorant Receptors in unknown sensillar types. Thick “Yes/No” arrows indicate higher probabilities and thin decision arrows indicate lower probabilities.
Mentions: Given the diversity of sensillar types (19 types in antenna and 3 types in maxillary palps), identification of each target sensilla for measurement of olfactory responses can be challenging and time-consuming (Fig 1). One method to circumvent this is to use the GAL4/UAS binary expression system [8, 9] to mis-express individual ORs in an easily identified basiconic sensilla (ab3) that houses a neuron lacking its endogenous receptor (the empty neuron system, genotype: Δhalo/Δhalo; Or22a-Gal4/UAS-OrX; [10]). This has proved to be an extremely powerful approach to define the odor profiles of many ORs [6, 7, 11]. However, several odorant receptors do not function in the empty neuron system (e.g, pheromone receptors, [12]), possibly because essential factors are lacking in the ab3A neuron or absent in the lymph surrounding the neuron [13, 14]. Therefore, direct measurement of neuronal activities in native sensilla remains the most reliable way to characterize the odor-activation profiles of individual ORNs. However, this can be particularly challenging for olfactory neurons that are sparse, or if odor-properties are not well defined.

Bottom Line: Drosophila olfactory receptor neurons are found within specialized sensory hairs on antenna and maxillary palps.Fluorescence-guided SSR further revealed that two antennal trichoid sensilla types should be re-classified as intermediate sensilla.This approach provides a simple and practical addition to a proven method for investigating olfactory neurons, and can be extended by the addition of UAS-geneX effectors for gain-of-function or loss-of-function studies.

View Article: PubMed Central - PubMed

Affiliation: The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.

ABSTRACT
Drosophila olfactory receptor neurons are found within specialized sensory hairs on antenna and maxillary palps. The linking of odorant-induced responses to olfactory neuron activities is often accomplished via Single Sensillum Recordings (SSR), in which an electrode inserted into a single sensory hair records the neuronal activities of all the neurons housed in that sensillum. The identification of the recorded sensillum requires matching the neuronal responses with known odor-response profiles. To record from specific sensilla, or to systematically screen all sensillar types, requires repetitive and semi-random SSR experiments. Here, we validate an approach in which the GAL4/UAS binary expression system is used for targeting specific sensilla for recordings. We take advantage of available OrX-Gal4 lines, in combination with recently generated strong membrane targeted GFP reporters, to guide electrophysiological recordings to GFP-labeled sensilla. We validate a full set of reagents that can be used to rapidly screen the odor-response profiles of all basiconic, intermediate, and trichoid sensilla. Fluorescence-guided SSR further revealed that two antennal trichoid sensilla types should be re-classified as intermediate sensilla. This approach provides a simple and practical addition to a proven method for investigating olfactory neurons, and can be extended by the addition of UAS-geneX effectors for gain-of-function or loss-of-function studies.

No MeSH data available.