کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5530479 1549311 2017 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Calcium signalling in Drosophila photoreceptors measured with GCaMP6f
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی بیولوژی سلول
پیش نمایش صفحه اول مقاله
Calcium signalling in Drosophila photoreceptors measured with GCaMP6f
چکیده انگلیسی


- Fruitflies generated expressing GCaMP6f in photoreceptors using the opsin promoter.
- Quantitative in vivo Ca2+ imaging in completely intact flies as well as dissociated cells.
- Ca2+ rise in Ca2+ free bath abolished in Na+/Ca2+ exchanger mutants.
- Ca2+ free rise due to re-equilibration of Na+/Ca2+ exchange following Na+ influx.
- No significant light-induced release of Ca2+ from internal stores.

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 Ca2+ influx in response to light, but whether Ca2+ is released from internal stores remains controversial. We generated flies expressing GCaMP6f in their photoreceptors and measured Ca2+ signals from dissociated cells, as well as in vivo by imaging rhabdomeres in intact flies. In response to brief flashes, GCaMP6f signals had latencies of 10-25 ms, reached 50% Fmax with ∼1200 effectively absorbed photons and saturated (ΔF/F0 ∼ 10-20) with 10000-30000 photons. In Ca2+ free bath, smaller (ΔF/F0 ∼4), long latency (∼200 ms) light-induced Ca2+ rises were still detectable. These were unaffected in InsP3 receptor mutants, but virtually eliminated when Na+ was also omitted from the bath, or in trpl;trp mutants lacking light-sensitive channels. Ca2+ free rises were also eliminated in Na+/Ca2+ exchanger mutants, but greatly accelerated in flies over-expressing the exchanger. These results show that Ca2+ free rises are strictly dependent on Na+ influx and activity of the exchanger, suggesting they reflect re-equilibration of Na+/Ca2+ exchange across plasma or intracellular membranes following massive Na+ influx. Any tiny Ca2+ free rise remaining without exchanger activity was equivalent to <10 nM (ΔF/F0 ∼0.1), and unlikely to play any role in phototransduction.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Cell Calcium - Volume 65, July 2017, Pages 40-51
نویسندگان
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