This study was supported by grants from the Japan Society for the Promotion of Science KAKENHI (https://www.jsps.go.jp/english/index.html) to N.U. (19K23758, 21K06295) and K.W. (19H03242, 20K21420, 21H00420), from the Ohsumi Frontier Science Foundation (https://www.ofsf.or.jp/en/) to K.W., and from the Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials (http://alliance.tagen.tohoku.ac.jp/english/) to N.U. and K.W. We thank Ms.&#160;Miyuki Shinohara (Hosei Univ.) for her help in preparing the figures.

A wild-type strain of Chlamydomonas reinhardtii, CC-125, was used for the present study. CC-125 was obtained from Chlamydomonas Resource Center (see Table of Materials) and maintained on a Tris-acetate-phosphate (TAP)16, 1.5% agarose medium at 20-25 &#176;C.
1. Cell culture
<ol>
	<li>Culture Chlamydomonas reinhardtii (CC-125) in TAP medium16 in a 12 h/12 h light-dark period (light conditions f...

<ol>
	<li>Szent-Gyorgyi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Free-energy+relations+and+contraction+of+actomyosin.">Free-energy relations and contraction of actomyosin.</a> Biological Bulletin. 96 (2), 140-161 (1949).</li><li>Hoffman-Berling, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adenosintriphosphat+als+betriebsstoff+von+zellbewegungen.">Adenosintriphosphat als betriebsstoff von zellbewegungen.</a> Biochimica et Biophysica Acta. 14, 182-194 (1954).</li><li>Naitoh, Y., Kaneko, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactivated+Triton-extracted+models+of+Paramecium:+modification+of+ciliary+movement+by+calcium+ions.">Reactivated Triton-extracted models of Paramecium: modification of ciliary movement by calcium ions.</a> Science. 176 (4034), 523-524 (1972).</li><li>Witman, G. 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S., Satir, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direction+of+active+sliding+of+microtubules+in+Tetrahymena+cilia.">Direction of active sliding of microtubules in Tetrahymena cilia.</a> Proceedings of the National Academy of Sciences of the United States of America. 74 (5), 2045-2049 (1977).</li><li>Fox, L. A., Sale, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direction+of+force+generated+by+the+inner+row+of+dynein+arms+on+flagellar+microtubules.">Direction of force generated by the inner row of dynein arms on flagellar microtubules.</a> Journal of Cell Biology. 105 (4), 1781-1787 (1987).</li><li>Kamiya, R., Yagi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+diversity+of+axonemal+dyneins+as+assessed+by+in+vitro+and+in+vivo+motility+assays+of+Chlamydomonas+mutants.">Functional diversity of axonemal dyneins as assessed by in vitro and in vivo motility assays of Chlamydomonas mutants.</a> Zoolog Science. 31 (10), 633-644 (2014).</li><li>Kamiya, R., Witman, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Submicromolar+levels+of+calcium+control+the+balance+of+beating+between+the+two+flagella+in+demembranated+models+of+Chlamydomonas.">Submicromolar levels of calcium control the balance of beating between the two flagella in demembranated models of Chlamydomonas.</a> Journal of Cell Biology. 98 (1), 97-107 (1984).</li><li>Okita, N., Isogai, N., Hirono, M., Kamiya, R., Yoshimura, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phototactic+activity+in+Chlamydomonas+'non-phototactic'+mutants+deficient+in+Ca2+-dependent+control+of+flagellar+dominance+or+in+inner-arm+dynein.">Phototactic activity in Chlamydomonas 'non-phototactic' mutants deficient in Ca2+-dependent control of flagellar dominance or in inner-arm dynein.</a> Journal of Cell Science. 118, 529-537 (2005).</li><li>Hyams, J. S., Borisy, G. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolated+flagellar+apparatus+of+Chlamydomonas:+characterization+of+forward+swimming+and+alteration+of+waveform+and+reversal+of+motion+by+calcium+ions+in+vitro.">Isolated flagellar apparatus of Chlamydomonas: characterization of forward swimming and alteration of waveform and reversal of motion by calcium ions in vitro.</a> Journal of Cell Science. 33, 235-253 (1978).</li><li>Fujiu, K., Nakayama, Y., Yanagisawa, A., Sokabe, M., Yoshimura, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chlamydomonas+CAV2+encodes+a+voltage-+dependent+calcium+channel+required+for+the+flagellar+waveform+conversion.">Chlamydomonas CAV2 encodes a voltage- dependent calcium channel required for the flagellar waveform conversion.</a> Current Biology. 19 (2), 133-139 (2009).</li><li>Bessen, M., Fay, R. B., Witman, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+control+of+waveform+in+isolated+flagellar+axonemes+of+Chlamydomonas.">Calcium control of waveform in isolated flagellar axonemes of Chlamydomonas.</a> Journal of Cell Biology. 86 (2), 446-455 (1980).</li><li>Wakabayashi, K., King, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+Chlamydomonas+reinhardtii+flagellar+motility+by+redox+poise.">Modulation of Chlamydomonas reinhardtii flagellar motility by redox poise.</a> Journal of Cell Biology. 173 (5), 743-754 (2006).</li><li>Saegusa, Y., Yoshimura, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=cAMP+controls+the+balance+of+the+propulsive+forces+generated+by+the+two+flagella+of+Chlamydomonas.">cAMP controls the balance of the propulsive forces generated by the two flagella of Chlamydomonas.</a> Cytoskeleton. 72 (8), 412-421 (2015).</li><li>Gorman, D. S., Levine, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytochrome+f+and+plastocyanin:+their+sequence+in+the+photosynthetic+electron+transport+chain+of+Chlamydomonas+reinhardi.">Cytochrome f and plastocyanin: their sequence in the photosynthetic electron transport chain of Chlamydomonas reinhardi.</a> Proceedings of the National Academy of Sciences of the United States of America. 54 (6), 1665-1669 (1965).</li><li>Takano, W., Hisabori, T., Wakabayashi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+estimation+of+cytosolic+ATP+concentration+from+the+ciliary+beating+frequency+in+the+green+alga+Chlamydomonas+reinhardtii.">Rapid estimation of cytosolic ATP concentration from the ciliary beating frequency in the green alga Chlamydomonas reinhardtii.</a> Journal of Biological Chemistry. 296, 100156 (2021).</li><li>Wakabayashi, K., Yagi, T., Kamiya, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ca2+-dependent+waveform+conversion+in+the+flagellar+axoneme+of+Chlamydomonas+mutants+lacking+the+central-pair/radial+spoke+system.">Ca2+-dependent waveform conversion in the flagellar axoneme of Chlamydomonas mutants lacking the central-pair/radial spoke system.</a> Cell Motility and the Cytoskeleton. 38 (1), 22-28 (1997).</li><li>Yueh, Y. G., Crain, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deflagellation+of+Chlamydomonas+reinhardtii+follows+a+rapid+transitory+accumulation+of+inositol+1,4,5-trisphosphate+and+requires+Ca2++entry.">Deflagellation of Chlamydomonas reinhardtii follows a rapid transitory accumulation of inositol 1,4,5-trisphosphate and requires Ca2+ entry.</a> Journal of Cell Biology. 123 (4), 869-875 (1993).</li><li>Wakabayashi, K., Ide, T., Kamiya, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium-dependent+flagellar+motility+activation+in+Chlamydomonas+reinhardtii+in+response+to+mechanical+agitation.">Calcium-dependent flagellar motility activation in Chlamydomonas reinhardtii in response to mechanical agitation.</a> Cell Motility and the Cytoskeleton. 66 (9), 736-742 (2009).</li><li>Ueki, N., Wakabayashi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detergent-extracted+Volvox+model+exhibits+an+anterior-posterior+gradient+in+flagellar+Ca2.">Detergent-extracted Volvox model exhibits an anterior-posterior gradient in flagellar Ca2.</a> Proceedings of the National Academy of Sciences of the United States of America. 115 (5), 1061-1068 (2018).</li><li>Tanno, A., 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=The+four-celled+Volvocales+green+alga+Tetrabaena+socialis+exhibits+weak+photobehavior+and+high-photoprotection+ability.">The four-celled Volvocales green alga Tetrabaena socialis exhibits weak photobehavior and high-photoprotection ability.</a> PLoS One. 16 (10), 0259138 (2021).</li></ol>

The authors have nothing to disclose.

There are two critical steps in this protocol. The first is a process known as demembranation, which needs to be carried out gently but thoroughly. Deciliation (i.e., detaching of cilia from the cell body) is induced by vigorous pipetting or vortexing, rendering the cell models immobile even after the addition of ATP. Typically, 5 &#215; 107 cells are suspended in ~0.5 mL of demembranation buffer (final cell density: 1 &#215; 108 cells/mL). The reactivation rate of the cell models would decrease if ...

The in vitro reactivation of demembranated motile cells is a valuable tool for studying the molecular basis for the regulatory mechanism of cell motility. Szent-Gy&#246;rgyi first demonstrated in vitro contraction of rabbit skeletal muscle fibers extracted with 50% glycerol by adding adenosine triphosphate (ATP)1. This experiment was the first to prove that ATP energizes muscle contraction. The methodology was soon applied to the study of ATP-energized ciliary/flagellar motility, such as sperm flagella2, Paramecium cilia3, and Chlamydomonas reinhardtii cilia (also called flagella)4 using non-ionic detergents for demembranation.
The unicellular green alga C. reinhardtii is a model organism for studying cilia: it swims with two cilia by beating them like a human&#39;s breaststroke5. Ciliary motion is driven by dynein, a minus-end directed microtubule-based motor protein6,7. Ciliary dyneins can be classified into outer-arm dyneins and inner-arm dyneins. Mutants lacking each kind of dynein have been isolated as slow-swimming mutants with different motility abnormalities. Detailed in vitro motility analysis of these mutants has significantly advanced dynein research8.
Many important findings have been achieved utilizing this method and its derivatives since the in vitro reactivation experiment of demembranated C. reinhardtii cells (cell models) was established. Reactivation of cell models in a series of Ca2+ buffers, for example, showed9 that two cilia are differently regulated by submicromolar Ca2+, and this asymmetrical cilia control enables the phototactic orientation of C. reinhardtii10. Furthermore, both cilia show waveform conversion from the forward swimming mode (called asymmetric waveform) to the backward swimming mode (called symmetric waveform that appears for a short period when cells are photo- or mechano-shocked)11,12. This waveform conversion is regulated by submillimolar Ca2+, which was shown by the reactivation of the so-called nucleoflagellar apparatus (a complex containing two cilia, the basal bodies, the structures linking the basal bodies with the nucleus, and the remnant of the nucleus)11 or demembranated axonemes of isolated cilia13. Other than Ca2+, redox (reduction-oxidation) poise is a signal that regulates the ciliary beating frequency, which was shown by reactivation of cell models in redox buffers containing different ratios of reduced glutathione vs. oxidized glutathione14. In addition, cyclic adenosine monophosphate (cAMP) asymmetrically regulates two cilia, which was shown by the reactivation of axonemes with photocleavable caged cAMP15. These in vitro findings, combined with genetic findings, have led to a deeper understanding of the molecular mechanisms of cilia regulation in C. reinhardtii.
A protocol for reactivating the cell models is described here. The method is simple, allows for various modifications, and can be applied to multiple organisms that move with cilia. However, because demembranated cells are fragile, it requires some tips to reactivate the motility of cell models with good efficiency while preventing deciliation.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.5 mL plastic tube</td>
			<td>QSP</td>
			<td>502-PLN-Q</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL conical tube</td>
			<td>SARSTEDT</td>
			<td>62.554.502</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 5&#39;-triphosphate disodium salt hydrate (ATP)</td>
			<td>Sima-Aldrich</td>
			<td>A2383</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>KUBOTA</td>
			<td>2800</td>
			<td></td>
		</tr>
		<tr>
			<td>Chlamydomonas strain CC-125</td>
			<td>Chlamydomonas Resource Center</td>
			<td></td>
			<td>https://www.chlamycollection.org/</td>
		</tr>
		<tr>
			<td>Creatine kinase</td>
			<td>Merck</td>
			<td>CK-RO</td>
			<td></td>
		</tr>
		<tr>
			<td>Creatine phosphate</td>
			<td>Merck</td>
			<td>CRPHO-RO</td>
			<td></td>
		</tr>
		<tr>
			<td>Dithiothreitol (DTT)</td>
			<td>Nakalai tesque</td>
			<td>14128-46</td>
			<td></td>
		</tr>
		<tr>
			<td>GEDTA(EGTA)</td>
			<td>Dojindo</td>
			<td>G002</td>
			<td></td>
		</tr>
		<tr>
			<td>Hepes</td>
			<td>Dojindo</td>
			<td>GB70</td>
			<td></td>
		</tr>
		<tr>
			<td>Igepal CA-630</td>
			<td>Sigma-Aldrich</td>
			<td>I8896</td>
			<td>IUPAC name is octylphenoxypolyethoxyethanol: IGEPAL CA-630 is a substitute for Nonidet P-40 (NP-40); NP-40 is no longer available in Sigma-Aldrich.</td>
		</tr>
		<tr>
			<td>MgSO4-7H2O</td>
			<td>Nakalai tesque</td>
			<td>21002-85</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus</td>
			<td>BX-53</td>
			<td></td>
		</tr>
		<tr>
			<td>Pasteur pipette</td>
			<td>fisher scientific</td>
			<td>13-678-20C</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylene glycol, Mr 20,000</td>
			<td>Merck</td>
			<td>8.18897.1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Pottasium acetate</td>
			<td>Nakalai tesque</td>
			<td>28434-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Hydroxide</td>
			<td>Nacalai</td>
			<td>31511-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>FUJIFILM Wako Pure Chemical Corporation</td>
			<td>196-00015</td>
			<td></td>
		</tr>
	</tbody>
</table>

reactivation of demembranated cell models in chlamydomonas reinhardtii

Since the historical experiment on the contraction of glycerinated muscle by adding ATP, which Szent-Gy&#246;rgyi demonstrated in the mid-20th century, in vitro reactivation of demembranated cells has been a traditional and potent way to examine cell motility. The fundamental advantage of this experimental method is that the composition of the reactivation solution may be easily changed. For example, a high-Ca2+ concentration environment that occurs only temporarily due to membrane excitation in vivo can be replicated in the lab. Eukaryotic cilia (a.k.a. flagella) are elaborate motility machinery whose regulatory mechanisms are still to be clarified. The unicellular green alga Chlamydomonas reinhardtii is an excellent model organism in the research field of cilia. The reactivation experiments using demembranated cell models of C. reinhardtii and their derivatives, such as demembranated axonemes of isolated cilia, have significantly contributed to understanding the molecular mechanisms of ciliary motility. Those experiments clarified that ATP energizes ciliary motility and that various cellular signals, including Ca2+, cAMP, and reactive oxygen species, modulate ciliary movements. The precise method for demembranation of C. reinhardtii cells and reactivation of the cell models is described here.

The demembranation and reactivation process in C. reinhardtii wild type strain (CC-125) is shown here. The culture 2 days after inoculation became a light green color (step 1.1) (Figure 1). Cells were collected (step 2.1), washed (step 2.2), and demembranated (step 2.5).&#160;After demembranation, all cell models became immotile (step 2.7). The demembranated cilia (called axonemes) remain attached to the cell body, which shows that the immotility of the cell models is not caused by ...

Watch this Scientific Journal Video about Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii at JoVE.com

Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii

The in vitro reactivation of motile cells is a crucial experiment in understanding the mechanisms of cell motility. The protocol describes reactivating the demembranated cell models of Chlamydomonas reinhardtii, a model organism to study cilia/flagella.

Reactivation of Demembranated Cell Models in Chlamydomonas reinhardtii

Since the historical experiment on the contraction of glycerinated muscle by adding ATP, which Szent-Gy&#246;rgyi demonstrated in the mid-20th century, in ...

This method can help to understand which factors affect cilia motility. The main advantage of this technique is that the phenomena that occur only temporarily in vivo, such inversion of calcium ion concentrations in cilia can be continuously observed in vitro. This method contributes specifically to the research field of motile cilia.It would be difficult for beginners to perform the demembranation step. Hence, it is highly recommended to carry out the steps gently but precisely. Begin by centrifuging approximately 10 milliliters of Chlamydomonas reinhardtii culture at 1, 000 RCF at 20 degrees Celsius for three minutes.Decant the supernatant and aspirate the remnant by a Pasteur pipette. Resuspend the precipitates in approximately five milliliters of washing buffer. Centrifuge cells in the washing buffer at 1, 000 RCF for three minutes at 20 degrees Celsius.Discard the supernatant carefully with a pipette. Add approximately 0.5 milliliters of demembranation buffer to the cell pellet. Shake the tube gently to roughly suspend the cells in the buffer, then put the tube on ice.Suspend the remaining cell pellet gently with a pipette and place the tube on the ice again. Take 5 to 10 microliters of the cell model, dilute tenfold with the dilution buffer, and observe under the microscope to confirm all the cell models are demembranated and not swimming. In a 0.5-milliliter tube, mix 80 microliters of reactivation solution, 10 microliters of ATP solution, and 10 microliters of cell models by tapping the tube.Put approximately 30 microliters of the mixed solution onto a glass slide and gently place a cover slip on it with spacers to avoid a mechanical shock to the cell model. Observe the reactivated cell models under a microscope. After demembranation of the C.reinhardtii culture, all cell models became immotile and the demembranated cilia remained attached to the cell body, confirming that the immotility of the cell models was not caused by de-ciliation.After mixing the cell models with the reactivation buffer in ATP, more than 50%of cell models became motile. Even without the ATP regeneration system, the reactivated cells continued to move for approximately 90 minutes with a final ATP concentration of one millimolar before gradually stopping. The demembranation step is critical.All the cells should stop swimming, but they should not be mixed so strongly that de-ciliation occurs. Researchers can modify this protocol to include reagents such as calcium ions or cyclic AMP, or perform experiments with a mutant lacking a particular protein to identify their biological role.

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2.0K vistas.  Hosei University. Este método puede ayudar a comprender qué factores afectan la motilidad de los cilios. La principal ventaja de esta técnica es que los fenómenos que ocurren solo temporalmente in vivo, dicha inversión de las concentraciones de iones de calcio en los cilios se puede observar continuamente in vitro. Este método contribuye específicamente al campo de investigación de los cilios móviles.Sería difícil para los principiantes realizar el paso de demembranación. Por lo tanto, es mu...