Name: imaging membrane potential with two types of genetically encoded fluorescent voltage sensors
Uploaded: 2016-02-04T14:00:00
Description: Watch this Scientific Journal Video about Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors at JoVE.com

This work was supported by the World Class Institute (WCI) program of the National Research Foundation of Korea funded by Ministry of Education, Science, and Technology of Korea Grant WCI 2009-003 and Korea Institute of Science and Technology Institutional Program Project 2E24210. Sungmoo Lee was supported by Global Ph.D. Fellowship program (NRF-2013H1A2A1033344) of the National Research Foundation (NRF) under the Ministry of Education (MOE, Korea).

Ethics statement: The animal experiment protocol was approved by the Institutional Animal Care and Use Committee at KIST animal protocol 2014-001.
1. Equipment Setup
<ol>
	<li>Imaging setup
	<ol>
		<li>Place an inverted fluorescence microscope on a vibration isolation table. Use a high magnification (60X oil immersion lens with 1.35 numerical aperture) objective lens and a filter cube equipped with a dichroic mirror and filters suitable for the fluorescent proteins used for the voltage imagi...

<ol>
	<li>Salzberg, B. M., Davila, H. V., Cohen, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+recording+of+impulses+in+individual+neurones+of+an+invertebrate+central+nervous+system.">Optical recording of impulses in individual neurones of an invertebrate central nervous system.</a> Nature. 246, 508-509 (1973).</li><li>Cohen, L. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+axon+fluorescence+during+activity:+molecular+probes+of+membrane+potential.">Changes in axon fluorescence during activity: molecular probes of membrane potential.</a> J. Membrane Biol. 19, 1-36 (1974).</li><li>Tasaki, I., Warashina, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dye-membrane+interaction+and+its+changes+during+nerve+excitation.">Dye-membrane interaction and its changes during nerve excitation.</a> Photochem Photobiol. 24, 191-207 (1976).</li><li>Grinvald, A., Hildesheim, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=VSDI:+a+new+era+in+functional+imaging+of+cortical+dynamics.">VSDI: a new era in functional imaging of cortical dynamics.</a> Nat Rev Neurosci. 5, 874-885 (2004).</li><li>Jin, L., Han, Z., Platisa, J., Wooltorton, J. R., Cohen, L. B., Pieribone, V. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+action+potentials+and+subthreshold+electrical+events+imaged+in+neurons+with+a+fluorescent+protein+voltage+probe.">Single action potentials and subthreshold electrical events imaged in neurons with a fluorescent protein voltage probe.</a> Neuron. 75, 779-785 (2012).</li><li>Cao, G., Platisa, J., Pieribone, V. A., Raccuglia, D., Kunst, M., Nitabach, M. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+targeted+optical+electrophysiology+in+intact+neural+circuits.">Genetically targeted optical electrophysiology in intact neural circuits.</a> Cell. 154, 904-913 (2013).</li><li>St-Pierre, F., Marshall, J. D., Yang, Y., Gong, Y., Schnitzer, M. J., Lin, M. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-fidelity+optical+reporting+of+neuronal+electrical+activity+with+an+ultrafast+fluorescent+voltage+sensor.">High-fidelity optical reporting of neuronal electrical activity with an ultrafast fluorescent voltage sensor.</a> Nat Neurosci. 17, 884-889 (2014).</li><li>Piao, H. H., Rajakumar, D., Kang, B. E., Kim, E. H., Baker, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combinatorial+mutagenesis+of+the+voltage-sensing+domain+enables+the+optical+resolution+of+action+potentials+firing+at+60+Hz+by+a+genetically+encoded+fluorescent+sensor+of+membrane+potential.">Combinatorial mutagenesis of the voltage-sensing domain enables the optical resolution of action potentials firing at 60 Hz by a genetically encoded fluorescent sensor of membrane potential.</a> J Neurosci. 35, 372-385 (2015).</li><li>Jung, A., Garcia, J. E., Kim, E., Yoon, B. J., Baker, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Linker+length+and+fusion+site+composition+improve+the+optical+signal+of+genetically+encoded+fluorescent+voltage+sensors.">Linker length and fusion site composition improve the optical signal of genetically encoded fluorescent voltage sensors.</a> Neurophoton. 2, 021012 (2015).</li><li>Dimitrov, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+and+characterization+of+an+enhanced+fluorescent+protein+voltage+sensor.">Engineering and characterization of an enhanced fluorescent protein voltage sensor.</a> PLoS One. 2, e440 (2007).</li><li>Lam, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+FRET+dynamic+range+with+bright+green+and+red+fluorescent+proteins.">Improving FRET dynamic range with bright green and red fluorescent proteins.</a> Nat Methods. 9, 1005-1012 (2012).</li><li>Sung, U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developing+fast+fluorescent+protein+voltage+sensors+by+optimizing+FRET+interactions.">Developing fast fluorescent protein voltage sensors by optimizing FRET interactions.</a> PLoS One. 10, e0141585 (2015).</li><li>Kralj, J. M., Douglass, A. D., Hochbaum, D. R., Maclaurin, D., Cohen, A. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+recording+of+action+potentials+in+mammalian+neurons+using+a+microbial+rhodopsin.">Optical recording of action potentials in mammalian neurons using a microbial rhodopsin.</a> Nat Methods. 9, 90-95 (2012).</li><li>Flytzanis, N. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Archaerhodopsin+variants+with+enhanced+voltage-sensitive+fluorescence+in+mammalian+and+Caenorhabditis+elegans+neurons.">Archaerhodopsin variants with enhanced voltage-sensitive fluorescence in mammalian and Caenorhabditis elegans neurons.</a> Nat Commun. 5, 4894 (2014).</li><li>Hochbaum, D. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=All-optical+electrophysiology+in+mammalian+neurons+using+engineered+microbial+rhodopsins.">All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins.</a> Nat Methods. 11, 825-833 (2014).</li><li>Gong, Y., Wagner, M. J., Zhong Li, J., Schnitzer, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+neural+spiking+in+brain+tissue+using+FRET-opsin+protein+voltage+sensors.">Imaging neural spiking in brain tissue using FRET-opsin protein voltage sensors.</a> Nat Commun. 5, 3674 (2014).</li><li>Zou, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bright+and+fast+multicoloured+voltage+reporters+via+electrochromic+FRET.">Bright and fast multicoloured voltage reporters via electrochromic FRET.</a> Nat Commun. 5, 4625 (2014).</li><li>Chanda, B., Blunck, R., Faria, L. C., Schweizer, F. E., Mody, I., Bezanilla, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+hybrid+approach+to+measuring+electrical+activity+in+genetically+specified+neurons.">A hybrid approach to measuring electrical activity in genetically specified neurons.</a> Nat Neurosci. 8, 1619-1626 (2005).</li><li>Wang, D., McMahon, S., Zhang, Z., Jackson, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybrid+voltage+sensor+imaging+of+electrical+activity+from+neurons+in+hippocampal+slices+from+transgenic+mice.">Hybrid voltage sensor imaging of electrical activity from neurons in hippocampal slices from transgenic mice.</a> J Neurophysiol. 108, 3147-3160 (2012).</li><li>Weigel, S., Flisikowska, T., Schnieke, A., Luksch, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybrid+voltage+sensor+imaging+of+eGFP-F+expressing+neurons+in+chicken+midbrain+slices.">Hybrid voltage sensor imaging of eGFP-F expressing neurons in chicken midbrain slices.</a> J Neurosci Methods. 233, 28-33 (2014).</li><li>Waters, J. C., Sluder, G., Wolf, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Live-Cell+Fluorescence+Imaging.">Live-Cell Fluorescence Imaging.</a> Methods in Cell Biology Volume 81. , 115-140 (2007).</li><li>Kaech, S., Banker, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culturing+hippocampal+neurons.">Culturing hippocampal neurons.</a> Nat Protoc. 1, 2406-2415 (2006).</li><li>Beaudoin, G. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culturing+pyramidal+neurons+from+the+early+postnatal+mouse+hippocampus+and+cortex.">Culturing pyramidal neurons from the early postnatal mouse hippocampus and cortex.</a> Nat Protoc. 7, 1741-1754 (2012).</li><li>Jiang, M., Chen, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+Ca2+-phosphate+transfection+efficiency+in+low-density+neuronal+cultures.">High Ca2+-phosphate transfection efficiency in low-density neuronal cultures.</a> Nat Protoc. 1, 695-700 (2006).</li><li>Molleman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Patch clamping: an introductory guide to patch clamp electrophysiology. , 101-102 (2003).</li><li>Osorio, N., Delmas, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patch+clamp+recording+from+enteric+neurons+in+situ.">Patch clamp recording from enteric neurons in situ.</a> Nat Protoc. 6, 15-27 (2010).</li><li>Schroder, M., Kaufman, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mammalian+unfolded+protein+response.">The mammalian unfolded protein response.</a> Annu Rev Biochem. 74, 739-789 (2005).</li><li>Wilt, B. A., Fitzgerald, J. E., Schnitzer, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photon+shot+noise+limits+on+optical+detection+of+neuronal+spikes+and+estimation+of+spike+timing.">Photon shot noise limits on optical detection of neuronal spikes and estimation of spike timing.</a> Biophys J. 104, 51-62 (2013).</li><li>Lundby, A., Mutoh, H., Dimitrov, D., Akemann, W., Knopfel, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+of+a+genetically+encodable+fluorescent+voltage+sensor+exploiting+fast+Ci-VSP+voltage-sensing+movements.">Engineering of a genetically encodable fluorescent voltage sensor exploiting fast Ci-VSP voltage-sensing movements.</a> PLoS One. 3, e2514 (2008).</li><li>Peterka, D. S., Takahashi, H., Yuste, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+voltage+in+neurons.">Imaging voltage in neurons.</a> Neuron. 69, 9-21 (2011).</li></ol>

The nervous system uses voltage in several different ways, inhibition causes a slight hyperpolarization, synaptic input causes a slight depolarization and an action potential results in a relatively large voltage change. The ability to measure changes in membrane potential by GEVIs offers the promising potential of analyzing several components of neuronal circuits simultaneously. In this report we demonstrate a fundamental method for imaging changes in the membrane potential using GEVIs.
A maj...

The major focus of this paper is to demonstrate the optical imaging of changes in membrane potentials in vitro using genetically encoded fluorescent proteins. Imaging changes in membrane potential offers the exciting possibility of studying the activity of neuronal circuits. When changes in membrane potential result in a fluorescence intensity change, each pixel of the camera becomes a surrogate electrode enabling nonintrusive measurements of neuronal activity. For over forty years, organic voltage-sensitive dyes have been useful for observing the changes in membrane potential 1-4. However, these dyes lack cellular specificity. In addition, some cell types are difficult to stain. Genetically encoded voltage indicators (GEVIs) overcome these limitations by having the cells to be studied specifically express the fluorescent voltage-sensitive probe.
There are three classes of GEVIs. The first class of GEVI uses the voltage-sensing domain from the voltage-sensing phosphatase with either a single fluorescent protein (FP) 5-9 or a F&#246;rster resonance energy transfer (FRET) pair 10-12. The second class of sensors uses microbial rhodopsin as a fluorescent indicator directly 13-15 or via electrochromic FRET 16,17. The third class utilizes two components, the genetic component being a membrane anchored FP and a second component being a membrane bound quenching dye 18-20. While the second and third classes are useful for in vitro and slice experiments19,20, only the first class of sensors are currently useful for in vivo analyses 6.
In this report we will demonstrate the imaging of membrane potential using the first class of GEVIs (Figure 1) in vitro. This first class of voltage sensors is the easiest to transition to in vivo imaging. Since GEVIs utilizing a voltage-sensing domain fused to a FP are about 50-fold brighter than the rhodopsin class of sensors, they can be imaged using arc lamp illumination rather than requiring an extremely powerful laser. Another consequence of the disparity in brightness is that the first class of GEVIs can easily exceed the auto-fluorescence of the brain. The rhodopsin-based probes cannot. The third class of sensor is just as bright as the first class but requires the addition of a chemical quencher which is difficult to administer in vivo.
We will, therefore, demonstrate the acquisition of a probe with a single FP (Bongwoori) 8 and a probe consisting of a FRET pair (Nabi 2) 12. The FRET constructs in this report are butterfly versions of VSFP-CR (voltage-sensitive fluorescent proteins - Clover-mRuby2) 11 consisting of a green fluorescent donor, Clover, and a red fluorescent acceptor, mRuby2, named Nabi 2.242 and Nabi 2.244 12. The introduction to these types of recordings should give researchers a better understanding of the type of information GEVIs can provide.
<img alt="Figure 1" src="/files/ftp_upload/53566/53566fig1.jpg" /> 
Figure 1.&#160;Two Types of Genetically Encoded Voltage Indicators (GEVIs) Imaged in This Report (A) A mono FP based GEVI having a trans-membrane voltage-sensing domain and a fluorescent protein. (B) A FRET based GEVI comprised of a trans-membrane voltage-sensing domain, a FRET donor and acceptor. <a href="https://www.jove.com/files/ftp_upload/53566/53566fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="0" cellpadding="0" cellspacing="0" width="923">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Inverted Microscope</td>
			<td style="width:165px;">Olympus</td>
			<td style="width:203px;">IX71</td>
			<td style="width:187px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">60X objective lens (numerical aperture = 1.35)</td>
			<td style="width:165px;">Olympus</td>
			<td style="width:203px;">UPLSAPO 60XO</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Excitation filter</td>
			<td style="width:165px;">Semrock</td>
			<td style="width:203px;">&#160;FF02-472/30</td>
			<td rowspan="3" style="width:187px;">For voltage imaging of super ecliptic pHluorin in Bongwoori</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Dichroic mirror</td>
			<td style="width:165px;">Semrock</td>
			<td style="width:203px;">FF495-Di03-25x36</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Emission filter</td>
			<td style="width:165px;">Semrock</td>
			<td style="width:203px;">FF01-497/LP</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:368px;">75W Xenon arc lamp</td>
			<td style="width:165px;">CAIRN</td>
			<td style="width:203px;">OptoSource Illuminator</td>
			<td style="width:187px;">LEDs and lasers are also effective light sources</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Slow speed CCD camera</td>
			<td style="width:165px;">Hitachi</td>
			<td style="width:203px;">KP-D20BU</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Dual port camera adaptor</td>
			<td style="width:165px;">Olympus</td>
			<td style="width:203px;">U-DPCAD</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">High speed CCD camera</td>
			<td style="width:165px;">RedShirtImaging, LLC</td>
			<td style="width:203px;">NeuroCCD-SM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Image splitter</td>
			<td style="width:165px;">CAIRN</td>
			<td style="width:203px;">Optosplit 2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Excitation filter</td>
			<td style="width:165px;">Semrock</td>
			<td style="width:203px;">FF01-475/23-25</td>
			<td rowspan="5" style="width:187px;">For voltage imaging of FRET pair based GEVI consisting of Clover and mRuby2)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Dichroic mirror</td>
			<td style="width:165px;">Semrock</td>
			<td style="width:203px;">FF495-Di03-25x36</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Emission filter</td>
			<td style="width:165px;">Chroma</td>
			<td style="width:203px;">ET520/40</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Dichroic mirror</td>
			<td style="width:165px;">Semrock</td>
			<td style="width:203px;">FF560-FDi01-25X36</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Emission filter</td>
			<td style="width:165px;">Chroma</td>
			<td style="width:203px;">ET645/75</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Vibration isolation system</td>
			<td style="width:165px;">Kinetic systems</td>
			<td style="width:203px;">250BM-IC, 5702E-3036-31</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Patching chamber</td>
			<td style="width:165px;">Warner instruments</td>
			<td style="width:203px;">RC-26G, 64-0235</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:368px;">#0 Micro Coverglass (22x40mm)</td>
			<td style="width:165px;">Electron Microscopy Sciences</td>
			<td style="width:203px;">72198-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Temperature controller</td>
			<td style="width:165px;">Warner instruments</td>
			<td style="width:203px;">TC-344B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">#0 (0.08~0.13mm) - 10mm diameter glass coverslip</td>
			<td style="width:165px;">Ted Pella</td>
			<td style="width:203px;">260366</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Lipofection agent</td>
			<td style="width:165px;">Life Technologies</td>
			<td style="width:203px;">11668-027</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Calcium phosphate reagent</td>
			<td style="width:165px;">Clontech - Takara</td>
			<td style="width:203px;">631312</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Patch clamp amplifier</td>
			<td style="width:165px;">HEKA</td>
			<td style="width:203px;">EPC 10 USB amplifier</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Multi-channel data acquisition software</td>
			<td style="width:165px;">HEKA</td>
			<td style="width:203px;">Patchmaster</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Image acquisition and analysis software</td>
			<td style="width:165px;">RedShirtImaging</td>
			<td style="width:203px;">Neuroplex</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Spreadsheet application software</td>
			<td style="width:165px;">Microsoft</td>
			<td style="width:203px;">Microsoft Excel 2010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Data analysis software</td>
			<td style="width:165px;">OriginLab</td>
			<td style="width:203px;">OriginPro 8.6.0</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:368px;">Demagnifier</td>
			<td style="width:165px;">Qioptiq LINOS</td>
			<td style="width:203px;">Optem standard camera coupler 0.38x SC38 J clamp</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:368px;">Confocal microscope</td>
			<td style="width:165px;">Nikon</td>
			<td style="width:203px;">Nikon A1R confocal microscope</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Anti-fade reagent</td>
			<td style="width:165px;">Life Technologies</td>
			<td style="width:203px;">P36930</td>
			<td></td>
		</tr>
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imaging membrane potential with two types of genetically encoded fluorescent voltage sensors

Genetically encoded voltage indicators (GEVIs) have improved to the point where they are beginning to be useful for in vivo recordings. While the ultimate goal is to image neuronal activity in vivo, one must be able to image activity of a single cell to ensure successful in vivo preparations. This procedure will describe how to image membrane potential in a single cell to provide a foundation to eventually image in vivo. Here we describe methods for imaging GEVIs consisting of a voltage-sensing domain fused to either a single fluorescent protein (FP) or two fluorescent proteins capable of F&#246;rster resonance energy transfer (FRET) in vitro. Using an image splitter enables the projection of images created by two different wavelengths onto the same charge-coupled device (CCD) camera simultaneously. The image splitter positions a second filter cube in the light path. This second filter cube consists of a dichroic and two emission filters to separate the donor and acceptor fluorescent wavelengths depending on the FPs of the GEVI. This setup enables the simultaneous recording of both the acceptor and donor fluorescent partners while the membrane potential is manipulated via whole cell patch clamp configuration. When using a GEVI consisting of a single FP, the second filter cube can be removed allowing the mirrors in the image splitter to project a single image onto the CCD camera.

Transiently transfected cells can exhibit significant variation in fluorescence intensity and the degree of plasma membrane expression. Even on the same coverslip some cells will have varying levels of internal fluorescence. This is most likely due to the amount of transfection agent absorbed by the cell. Occasionally, too much expression causes the cell to experience the unfolded protein response resulting in apoptosis 27 (bright, rounded cells, with high internal fluorescence...

Watch this Scientific Journal Video about Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors at JoVE.com

Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors

A method for imaging changes in membrane potential using genetically encoded voltage indicators is described.

Genetically encoded voltage indicators (GEVIs) have improved to the point where they are beginning to be useful for in vivo recordings. While the ultimate ...

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