The molecular basis for water taste in Drosophila. Nature

Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, CA, USA.
Nature (Impact Factor: 41.46). 04/2010; 465(7294):91-5. DOI: 10.1038/nature09011
Source: PubMed


The detection of water and the regulation of water intake are essential for animals to maintain proper osmotic homeostasis. Drosophila and other insects have gustatory sensory neurons that mediate the recognition of external water sources, but little is known about the underlying molecular mechanism for water taste detection. Here we identify a member of the degenerin/epithelial sodium channel family, PPK28, as an osmosensitive ion channel that mediates the cellular and behavioural response to water. We use molecular, cellular, calcium imaging and electrophysiological approaches to show that ppk28 is expressed in water-sensing neurons, and that loss of ppk28 abolishes water sensitivity. Moreover, ectopic expression of ppk28 confers water sensitivity to bitter-sensing gustatory neurons in the fly and sensitivity to hypo-osmotic solutions when expressed in heterologous cells. These studies link an osmosensitive ion channel to water taste detection and drinking behaviour, providing the framework for examining the molecular basis for water detection in other animals.

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Available from: Makoto Hiroi, Aug 13, 2014
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    • "), (22) Gr5a-GAL4 (Wang et al., 2004), (23) Gr66a- GAL4 (Scott et al., 2001), (24) Ir76b-GAL4 (Zhang et al., 2013), (25) ppk28-GAL4 (Cameron et al., 2010), (26) Ir76b-QF (Zhang et al., 2013), (27) QUAS-mtdTomato::3xHA (Potter et al., 2010), (28) lexAop-CD2::GFP (Lai & Lee, 2006), (29) 13xLexAop2- IVS-FRT-stop-FRT-spGFP11::CD4::HA-T2A-Brp D3 ::mCherry (attP2) (Karuppudurai et al., 2014), (30) UAS-Syb::spGFP1-10 (Karuppudurai et al., 2014). To label single cells by the FLP-out recombination method, wandering larvae, or early pupae were treated with 39 ° C heat shock for 20 min (for UAS-FRT-CD2, y -FRT-CD8::GFP ), 5 min (for 20xUAS-IVS-FRT-stop-FRT- spGFP1-10::CD4::HA ) or 0 – 2 min (for 13xLexAop2-IVS-FRT- stop-FRT-spGFP11::CD4::HA-T2A-Brp D3 ::mCherry (attP2) ), and then kept at 25 ° C until dissection. "
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    • "Previous studies had revealed excellent correspondence between stimulus-evoked electrophysiological responses in sensory neurons and calcium responses in their cell bodies and axon termini in olfactory and gustatory receptor neurons of fruit flies (de Bruyne et al., 2001; Suh et al., 2004; Pelz et al., 2006; Kwon et al., 2007; Cameron et al., 2010). Although we do not know the correlation between the calcium signals observed in the axons of subgroup-D JO neurons and their action potential responses, the tonic calcium response of subgroup-D JO neurons to vibrations of middle-range frequencies, a pulse song, and the anterior deflection observed in this study strongly suggests these signals would be transmitted to their downstream neural circuits. "
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