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      Intraciliary calcium oscillations initiate vertebrate left-right asymmetry

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          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Summary

          Background

          Bilateral symmetry during vertebrate development is broken at the left-right organizer (LRO) by ciliary motility and the resultant directional flow of extracellular fluid. However, how ciliary motility is perceived and transduced into asymmetrical intracellular signaling at the LRO remains controversial. Previous work has indicated that sensory cilia and polycystin-2 (Pkd2), a cation channel, are required for sensing ciliary motility, yet their function and the molecular mechanism linking both to left-right signaling cascades is unknown.

          Results

          Here, we report novel intraciliary calcium oscillations (ICOs) at the LRO that connect ciliary sensation of ciliary motility to downstream left-right signaling. Utilizing cilia-targeted genetically-encoded calcium indicators in live zebrafish embryos, we show that ICOs depend on Pkd2 and are left-biased at the LRO in response to ciliary motility. Asymmetric ICOs occur with onset of LRO ciliary motility, thus representing the earliest known LR asymmetric molecular signal. Suppression of ICOs using a cilia-targeted calcium sink demonstrates that they are essential for LR development.

          Conclusions

          These findings demonstrate that intraciliary calcium initiates LR development and identify cilia as a functional ion signaling compartment connecting ciliary motility and flow to molecular LR signaling.

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          Most cited references 64

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          Ultra-sensitive fluorescent proteins for imaging neuronal activity

          Summary Fluorescent calcium sensors are widely used to image neural activity. Using structure-based mutagenesis and neuron-based screening, we developed a family of ultra-sensitive protein calcium sensors (GCaMP6) that outperformed other sensors in cultured neurons and in zebrafish, flies, and mice in vivo. In layer 2/3 pyramidal neurons of the mouse visual cortex, GCaMP6 reliably detected single action potentials in neuronal somata and orientation-tuned synaptic calcium transients in individual dendritic spines. The orientation tuning of structurally persistent spines was largely stable over timescales of weeks. Orientation tuning averaged across spine populations predicted the tuning of their parent cell. Although the somata of GABAergic neurons showed little orientation tuning, their dendrites included highly tuned dendritic segments (5 - 40 micrometers long). GCaMP6 sensors thus provide new windows into the organization and dynamics of neural circuits over multiple spatial and temporal scales.
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            Optimization of a GCaMP calcium indicator for neural activity imaging.

            Genetically encoded calcium indicators (GECIs) are powerful tools for systems neuroscience. Recent efforts in protein engineering have significantly increased the performance of GECIs. The state-of-the art single-wavelength GECI, GCaMP3, has been deployed in a number of model organisms and can reliably detect three or more action potentials in short bursts in several systems in vivo. Through protein structure determination, targeted mutagenesis, high-throughput screening, and a battery of in vitro assays, we have increased the dynamic range of GCaMP3 by severalfold, creating a family of "GCaMP5" sensors. We tested GCaMP5s in several systems: cultured neurons and astrocytes, mouse retina, and in vivo in Caenorhabditis chemosensory neurons, Drosophila larval neuromuscular junction and adult antennal lobe, zebrafish retina and tectum, and mouse visual cortex. Signal-to-noise ratio was improved by at least 2- to 3-fold. In the visual cortex, two GCaMP5 variants detected twice as many visual stimulus-responsive cells as GCaMP3. By combining in vivo imaging with electrophysiology we show that GCaMP5 fluorescence provides a more reliable measure of neuronal activity than its predecessor GCaMP3. GCaMP5 allows more sensitive detection of neural activity in vivo and may find widespread applications for cellular imaging in general.
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              An expanded palette of genetically encoded Ca²⁺ indicators.

              Engineered fluorescent protein (FP) chimeras that modulate their fluorescence in response to changes in calcium ion (Ca(2+)) concentration are powerful tools for visualizing intracellular signaling activity. However, despite a decade of availability, the palette of single FP-based Ca(2+) indicators has remained limited to a single green hue. We have expanded this palette by developing blue, improved green, and red intensiometric indicators, as well as an emission ratiometric indicator with an 11,000% ratio change. This series enables improved single-color Ca(2+) imaging in neurons and transgenic Caenorhabditis elegans. In HeLa cells, Ca(2+) was imaged in three subcellular compartments, and, in conjunction with a cyan FP-yellow FP-based indicator, Ca(2+) and adenosine 5'-triphosphate were simultaneously imaged. This palette of indicators paints the way to a colorful new era of Ca(2+) imaging.
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                Author and article information

                Journal
                9107782
                8548
                Curr Biol
                Curr. Biol.
                Current biology : CB
                0960-9822
                1879-0445
                6 June 2015
                05 February 2015
                2 March 2015
                02 March 2016
                : 25
                : 5
                : 556-567
                Affiliations
                [1 ]Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
                [2 ]Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
                Author notes
                [# ]Correspondence and request for materials should be addressed to: martina.brueckner@ 123456yale.edu and zhaoxia.sun@ 123456yale.edu
                [3]

                Current address: School of Public Health, School of Medicine, Zhejiang University, Hangzhou, 310058, China

                [*]

                These authors contributed equally

                Article
                NIHMS661880
                10.1016/j.cub.2014.12.051
                4469357
                25660539
                © 2014 Published by Elsevier Ltd.

                This manuscript version is made available under the CC BY-NC-ND 4.0 license.

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                Article

                Life sciences

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