A complex peripheral code for salt taste in Drosophila
- University of British Columbia, Canada
Figures
Figure 1 with 1 supplement
A molecular map of the fly labellum.
(A) A schematic of sensillum identities in the fly labellum. (B) A summary of how GRN identities are currently viewed across the three sensillum types, with each color representing a GRN class with …
Figure 1—figure supplement 1
Molecular mapping of characterized and uncharacterized labellar GRN types.
(A) Labellum expression of Ppk23-Gal4 restricted with ChAT-Gal80. Arrow indicates an S-type sensillum with two Ppk23 +GRNs, indicating incomplete elimination of Ppk23chat expression. (B) Ppk23-Gal4 …
Figure 2 with 2 supplements
Salt activates or inhibits every GRN class.
(A) Schematic of calcium imaging preparation. Taste neurons are stimulated on the proboscis, while GCaMP6f fluorescence is recorded at the synaptic terminals in the SEZ. (B) Representative heat map …
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Figure 2—source data 1
Raw numerical data for Figure 2 and associated figure supplements.
- https://doi.org/10.7554/eLife.37167.008
Figure 2—figure supplement 1
IR94e neurons show weak, low sodium-specific responses to salt.
(A) Time curves of GCaMP6f signal in IR94e GRNs following stimulation with indicated tastants. Lines and shaded regions indicate mean ±SEM. (B) Peak changes during stimulation of IR94e neurons with …
Figure 2—figure supplement 2
Ppk23 neurons respond strongly to all salts and only weakly to pheromones.
(A) Time curves of GCaMP6f activation in Ppk23 GRNs following stimulation with 1 M solutions of various salts and sucrose. Lines and shaded regions indicate mean ±SEM. (B) Peak changes during …
Figure 3 with 1 supplement
Morphological and functional distinction between Ppk23 subclasses.
(A) Representative heat maps showing the activation Ppk23 GRNs in a single fly stimulated with 1 M NaCl and 100 mM caffeine. Salt primarily results in lateral activation, while bitter activates …
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Figure 3—source data 1
Raw numerical data for Figure 3 and associated figure supplements.
- https://doi.org/10.7554/eLife.37167.011
Figure 3—figure supplement 1
Ppk23glut GRNs respond to high salt.
(A) GCaMP6f expression was primarily restricted to Ppk23glut GRNs using Ppk23-Gal4 in combination with ChAT-Gal80. Lines and shaded regions represent mean ±SEM of responses over time, with …
Figure 4 with 3 supplements
IR76b is necessary for Gr64f and Ppk23glut, but not Gr66a, salt responses.
(A) GCaMP6f fluorescence changes over time for each indicated GRN type, following stimulation with the denoted tastants. Black lines are for control genotypes (IR76b1/+ background), red lines for IR7…
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Figure 4—source data 1
Raw numerical data for Figure 4 and associated figure supplements.
- https://doi.org/10.7554/eLife.37167.016
Figure 4—figure supplement 1
Ppk23 GRN salt responses require IR76b.
(A) GCaMP6f fluorescence changes over time for full Ppk23 projections. Black lines are for control genotypes (IR76b1/+ background), red lines for IR76b1/IR76b2 mutants. (B) Peak fluorescence changes …
Figure 4—figure supplement 2
A subset of GRN salt responses requires IR25a.
Peak values of GCaMP6f fluorescence changes for each GRN type in heterozygous controls (filled grey circles), IR25a mutants (open red circles), and rescues (filled red circles), following …
Figure 4—figure supplement 3
Ppk23 GRN salt responses do not require Ppk23 or Ppk29.
(A–B) Response curves (A) and peak values (B) for Ppk23 calcium responses in a Ppk23, Ppk29 mutant background. Values represent mean ±SEM, n = 14. Asterisks denote significant different from water …
Figure 5 with 3 supplements
Specific GRN contributions to salt attraction and avoidance.
(A) Low salt attraction in binary choice assay, following silencing of different GRN populations with Kir2.1. Positive values indicate preference for 50 mM NaCl plus 2 mM sucrose; negative values …
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Figure 5—source data 1
Raw numerical data for Figure 5 and associated figure supplements.
- https://doi.org/10.7554/eLife.37167.021
Figure 5—figure supplement 1
Silencing with tetanus toxin reveals a role for IR94e in low salt attraction.
Low salt attraction in binary choice assay, following silencing of different GRN populations with Tetanus toxin (TNT). Positive values indicate preference for 50 mM NaCl plus 2 mM sucrose; negative …
Figure 5—figure supplement 2
Ppk23glut and Gr66a GRNs differentially function in PER suppression by high salt, depending on internal state.
(A–B) High salt inhibition of PER in salt fed (left) or salt deprived (right) flies following silencing of Ppk23glut (A) or Gr66a (B) GRNs. Labellar PER was measured to 100 mM sucrose plus the …
Figure 5—figure supplement 3
Ppk23glut calcium responses are not modulated by salt deprivation.
GCaMP imaging of Ppk23glut GRN responses in flies that have been salt fed (filled grey circles) or salt deprived (open grey circles). Bars represent mean ±SEM of peak fluorescence changes during …
Figure 6
Salt deprivation modulates salt avoidance downstream of Ppk23glut.
(A) Schematic of closed-loop optogentic feeding assay, called the ‘sip triggered optogenetic behavior enclosure’ (STROBE). Each food is presented as a small drop containing 1% agar. Interactions …
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Figure 6—source data 1
Raw numerical data for Figure 6.
- https://doi.org/10.7554/eLife.37167.023
Figure 7
Model for salt encoding across different GRN classes in the labellum.
Line thickness indicates strength of the excitatory (arrows) or inhibitory (bars) effects of high and low salt on each GRN class, as well as the impact of each cell type on behavior.
Tables
Key resources table
| Reagent type (species) or resource | Designation | Source or reference | Identifiers | Additional information |
|---|---|---|---|---|
| Genetic reagent (D. melanogaster) | vGlutMI04979-Gal4 | Diao et al. (2015) | BDSC: 60312; RRID:BDSC_60312 | |
| Genetic reagent (D. melanogaster) | ChATMI04508-Gal4 | Diao et al. (2015) | BDSC: 60317; RRID:BDSC_60317 | |
| Genetic reagent (D. melanogaster) | vGlutMI04979-LexA::QFAD | Diao et al. (2015) | BDSC: 60314; RRID:BDSC_60314 | |
| Genetic reagent (D. melanogaster) | ChATMI04508- LexA::QFAD | Diao et al. (2015) | BDSC: 60319; RRID:BDSC_60319 | |
| Genetic reagent (D. melanogaster) | vGlutMI04979-Gal80 | Diao et al. (2015) | BDSC: 60316; RRID:BDSC_60316 | |
| Genetic reagent (D. melanogaster) | ChATMI04508-Gal80 | Diao et al. (2015) | BDSC: 60321; RRID:BDSC_60321 | |
| Genetic reagent (D. melanogaster) | ΔPpk23 | Thistle et al. (2012) | Flybase: FBal0277047 | |
| Genetic reagent (D. melanogaster) | ΔPpk29 | Thistle et al. (2012) | Flybase: FBal0277049 | |
| Genetic reagent (D. melanogaster) | Gr66a-LexA | Thistle et al. (2012) | Flybase: FBal0277069 | |
| Genetic reagent (D. melanogaster) | ppk28-LexA | Thistle et al. (2012) | Flybase: FBal0277050 | |
| Genetic reagent (D. melanogaster) | ppk23-Gal4 | Thistle et al. (2012) | Flybase: FBal0277044 | |
| Genetic reagent (D. melanogaster) | Gr64fLexA | Miyamoto et al. (2012) | Flybase: FBti0168176 | |
| Genetic reagent (D. melanogaster) | ppk23-LexA | Toda et al. (2012) | Flybase: FBst0051311 | |
| Genetic reagent (D. melanogaster) | IR76b-Gal4 | Zhang et al. (2013) | Flybase: FBtp0085485 | |
| Genetic reagent (D. melanogaster) | IR76b1 | Zhang et al. (2013) | Flybase: FBst0051309 | |
| Genetic reagent (D. melanogaster) | IR76b2 | Zhang et al. (2013) | Flybase: FBst0051310 | |
| Genetic reagent (D. melanogaster) | UAS-IR76b | Zhang et al. (2013) | Flybase: FBtp0085485 | |
| Genetic reagent (D. melanogaster) | IR25a1 | Benton et al. (2009) | Flybase: FBst0041736 | |
| Genetic reagent (D. melanogaster) | IR25a2 | Benton et al. (2009) | Flybase: FBst0041737 | |
| Genetic reagent (D. melanogaster) | UAS-IR25a | Abuin et al., 2011 | Flybase: FBst0041747 | |
| Genetic reagent (D. melanogaster) | Gr66a-Gal4 | Wang et al. (2004) | Flybase: FBtp0014660 | |
| Genetic reagent (D. melanogaster) | Gr64f-Gal4 | Dahanukar et al. (2007) | Flybase: FBti0162678 | |
| Genetic reagent (D. melanogaster) | Gr64f-Gal4 | Dahanukar et al. (2007) | Flybase: FBtp0057275 | |
| Genetic reagent (D. melanogaster) | Ppk28-Gal4 | Cameron et al. (2010) | Flybase: FBtp0054514 | |
| Genetic reagent (D. melanogaster) | LexAop-CD2::GFP | Lai and Lee (2006) | Flybase: FBti0186090 | |
| Genetic reagent (D. melanogaster) | UAS-Kir2.1 | Baines et al. (2001) | Flybase: FBti0017552 | |
| Genetic reagent (D. melanogaster) | tub-Gal80ts | McGuire et al. (2004) | Flybase: FBti0027797 | |
| Genetic reagent (D. melanogaster) | IR94e-Gal4 | Tirián and Dickson, 2017 | VDRC: v207582 | |
| Genetic reagent (D. melanogaster) | w1118 | Bloomington Drosophila Stock Center | BDSC: 3605; RRID:BDSC_3605 | |
| Genetic reagent (D. melanogaster) | LexAop-Gal80 | Bloomington Drosophila Stock Center | BDSC: 32214; RRID:BDSC_32214 | |
| Genetic reagent (D. melanogaster) | LexAop-GCaMP6f | Bloomington Drosophila Stock Center | BDSC: 44277; RRID:BDSC_44277 | |
| Genetic reagent (D. melanogaster) | UAS-GCaMP6f | Bloomington Drosophila Stock Center | BDSC: 42747; RRID:BDSC_42747 | |
| Genetic reagent (D. melanogaster) | UAS-GCaMP6f | Bloomington Drosophila Stock Center | BDSC: 52869; RRID:BDSC_52869 | |
| Genetic reagent (D. melanogaster) | UAS-CsChrimson | Bloomington Drosophila Stock Center | BDSC: 55135; RRID:BDSC_55135 | |
| Genetic reagent (D. melanogaster) | UAS-TNT | Bloomington Drosophila Stock Center | BDSC: 28838; RRID:BDSC_28838 | |
| Genetic reagent (D. melanogaster) | UAS-impTNT | Bloomington Drosophila Stock Center | BDSC: 28840; RRID:BDSC_28840 | |
| Antibody | anti-GFP | Abcam, Cambridge, UK, | #13970; RRID:AB_300798 | (1:1000 dilution) |
| Antibody | anti-RFP | Rockland Immunochemicals, Pottstown, PA, | #600-401-379; RRID:AB_2209751 | (1:200 dilution) |
| Antibody | anti-chicken Alexa 488 | Abcam | #150169; RRID:AB_2636803 | (1:200 dilution) |
| Antibody | anti-rabbit Alexa 647 | Thermo Fisher Scientific, Waltham, MA, | #A21245; RRID:AB_2535813 | (1:200 dilution) |
| Antibody | anti-brp | Developmental Studies Hybridoma Bank | #nc82; RRID:AB_2314866 | (1:50 dilution) |
| Antibody | anti-rabbit Alexa 568 | Thermo Fisher Scientific, Waltham, MA, | #A11036; RRID:AB_10563566 | (1:200 dilution) |
| Chemical compound, drug | All trans-Retinal | Sigma-Aldrich | #R2500 | |
| Chemical compound, drug | Sucrose | Sigma-Aldrich | #S7903 | |
| Chemical compound, drug | NaCl | Sigma-Aldrich | #S7653 | |
| Chemical compound, drug | KCl | Sigma-Aldrich | #P9541 | |
| Chemical compound, drug | NaBr | Sigma-Aldrich | #S4547 | |
| Chemical compound, drug | KBr | Sigma-Aldrich | #221864 | |
| Chemical compound, drug | CsCl | Sigma-Aldrich | #289329 | |
| Chemical compound, drug | CaCl2 | BDH chemicals | #BDH4524 | |
| Chemical compound, drug | Lobeline hydrochloride | Sigma-Aldrich | #141879 | |
| Chemical compound, drug | Caffeine | Sigma-Aldrich | #C0750 | |
| Chemical compound, drug | 7,11-heptacosadiene (7,11-HC) | Caymen chemical company | #10012567 | |
| Chemical compound, drug | 7,11-nonacosadiene (7,11-NC) | Caymen chemical company | #9000314 | |
| Chemical compound, drug | 7-tricosene (7 T) | Caymen chemical company | #9000313 | |
| Chemical compound, drug | Cis-vaccenyl acetate (c-VA) | Caymen chemical company | #10010101 | |
| Chemical compound, drug | Erioglaucine | Spectrum chemical | #FD110 | |
| Chemical compound, drug | Amaranth | Sigma-Aldrich | #A1016 | |
| Software, algorithm | STROBE executable | Chan, 2018a | github: https://github.com/rcwchan/STROBE_software/ (copy archived at https://github.com/elifesciences-publications/STROBE_software) | |
| Software, algorithm | STROBE post- processing | Chan, 2018a | github: https://github.com/rcwchan/STROBE_software/ (copy archived at https://github.com/elifesciences-publications/STROBE_software) | |
| Software, algorithm | STROBE VHDL code | Chan, 2018b | github: https://github.com/rcwchan/STROBE-fpga (copy archived at https://github.com/elifesciences-publications/STROBE-fpga) | |
| Software, algorithm | ImageJ | Schneider et al. (2012) | https://imagej.nih.gov/ij; RRID:SCR_003070 | |
| Software, algorithm | Prism 6 | Graphpad | RRID:SCR_002798 | |
| Software, algorithm | Photoshop | Adobe | RRID:SCR_014199 | |
| Software, algorithm | Illustrator | Adobe | RRID:SCR_010279 |
Additional files
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Transparent reporting form
- https://doi.org/10.7554/eLife.37167.025
