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dc.contributor.authorAsteriti, Sabrinaen
dc.contributor.authorLiu, C-Hen
dc.contributor.authorHardie, Rogeren
dc.date.accessioned2017-05-01T11:34:09Z
dc.date.available2017-05-01T11:34:09Z
dc.identifier.issn0143-4160
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/263914
dc.description.abstract$\textit{Drosophila}$ phototransduction is mediated by phospholipase C leading to activation of cation channels (TRP and TRPL) in the 30000 microvilli forming the light-absorbing rhabdomere. The channels mediate massive Ca$^{2+}$ influx in response to light, but whether Ca$^{2+}$ is released from internal stores remains controversial. We generated flies expressing GCaMP6f in their photoreceptors and measured Ca$^{2+}$ signals from dissociated cells, as well as $\textit{in vivo}$ by imaging rhabdomeres in intact flies. In response to brief flashes, GCaMP6f signals had latencies of 10–25 ms, reached 50% $\textit{F}$max with $\sim$ 1200 effectively absorbed photons and saturated ($\textit{ΔF/F}$$_{0}$ $\sim$ 10–20) with 10000–30000 photons. In Ca$^{2+}$ free bath, smaller ($\textit{ΔF/F}$$_{0}$ $\sim$ 4), long latency ($\sim$ 200 ms) light-induced Ca$^{2+}$ rises were still detectable. These were unaffected in InsP$_{3}$ receptor mutants, but virtually eliminated when Na+ was also omitted from the bath, or in trpl;trp mutants lacking light-sensitive channels. Ca$^{2+}$ free rises were also eliminated in Na+/Ca$^{2+}$ exchanger mutants, but greatly accelerated in flies over-expressing the exchanger. These results show that Ca$^{2+}$ free rises are strictly dependent on Na+ influx and activity of the exchanger, suggesting they reflect re-equilibration of Na+/Ca$^{2+}$ exchange across plasma or intracellular membranes following massive Na+ influx. Any tiny Ca$^{2+}$ free rise remaining without exchanger activity was equivalent to <10 nM ($\textit{ΔF/F}$$_{0}$ $\sim$ 0.1), and unlikely to play any role in phototransduction.
dc.description.sponsorshipThe authors thank Dr Marten Postma for comments on the MS. This project received funding from the Biotechnology and Biological Sciences Research Council (BB/M00706/1 and BB/J009253/1; RCH, C-HL) and Horizon 2020 “European Union’s Horizon 2020 research and innovation programme under grant agreement No (658818-FLYghtCaRe RCH, SA).
dc.languageengen
dc.language.isoenen
dc.publisherElsevier
dc.rightsAttribution 4.0 Internationalen
dc.rightsAttribution 4.0 Internationalen
dc.rightsAttribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.subjectCalcium imagingen
dc.subjectgenetically encoded calcium indicatorsen
dc.subjectInsP(3)en
dc.subjectNa/Ca exchangeren
dc.subjectphospholipase Cen
dc.subjectphototransductionen
dc.subjectTRP channelsen
dc.titleCalcium signalling in $\textit{Drosophila}$ photoreceptors measured with GCaMP6fen
dc.typeArticle
prism.publicationNameCell Calciumen
dc.identifier.doi10.17863/CAM.9292
dcterms.dateAccepted2017-02-10en
rioxxterms.versionofrecord10.1016/j.ceca.2017.02.006en
rioxxterms.versionVoRen
rioxxterms.licenseref.urihttp://creativecommons.org/licenses/by/4.0/en
rioxxterms.licenseref.startdate2017-02-10en
dc.contributor.orcidHardie, Roger [0000-0001-5531-3264]
dc.identifier.eissn1532-1991
rioxxterms.typeJournal Article/Reviewen
pubs.funder-project-idBBSRC (BB/M007006/1)
pubs.funder-project-idBBSRC (BB/J009253/1)
pubs.funder-project-idEuropean Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (658818)
cam.issuedOnline2017-02-15en


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Attribution 4.0 International
Except where otherwise noted, this item's licence is described as Attribution 4.0 International