Special thanks to James Copti for editing of the manuscript. We also gratefully acknowledge funding to JN from the German Research foundation (DFG) by the SFB 870 and SPP &#8220;Integrative Analysis of Olfaction&#8221; and SPP 1738 &#8220;Emerging roles of non-coding RNAs in nervous system development, plasticity &#38; disease&#8221;, SPP1757 &#8220;Glial heterogeneity&#8221;, and Excellence Strategy within the framework of the Munich Cluster for Systems Neurology (EXC 2145 SyNergy &#8211; ID 390857198).

All animals used in this protocol were kept under standard husbandry conditions, and experiments have been performed according to the handling guidelines and regulations of EU and the Government of Upper Bavaria (AZ 55.2-1-54-2532-0916).
1. Preparation of Plasmid Mixture for Electroporation
<ol>
	<li>Dilute the plasmid of interest in sterile water and add fast green stain stock solution [1 mg/mL]. Make sure that the final concentration of the plasmid is&#160; &#8764;1 &#181;g/&#181;L. Add th...

<ol>
	<li>Kaslin, J., Ganz, J., Brand, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proliferation,+neurogenesis+and+regeneration+in+the+non-mammalian+vertebrate+brain.">Proliferation, neurogenesis and regeneration in the non-mammalian vertebrate brain.</a> Philosophical Transactions of the Royal Society of London Series B Biological Sciences. 363 (1489), 101-122 (2008).</li><li>Baumgart, E. V., Barbosa, J. S., Bally-Cuif, L., Gotz, M., Ninkovic, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stab+wound+injury+of+the+zebrafish+telencephalon:+a+model+for+comparative+analysis+of+reactive+gliosis.">Stab wound injury of the zebrafish telencephalon: a model for comparative analysis of reactive gliosis.</a> Glia. 60 (3), 343-357 (2012).</li><li>Barbosa, 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=Live+imaging+of+adult+neural+stem+cell+behavior+in+the+intact+and+injured+zebrafish+brain.">Live imaging of adult neural stem cell behavior in the intact and injured zebrafish brain.</a> Science. 346 (6236), 789-793 (2015).</li><li>Kishimoto, N., Shimizu, K., Sawamoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+regeneration+in+a+zebrafish+model+of+adult+brain+injury.">Neuronal regeneration in a zebrafish model of adult brain injury.</a> Disease Model and Mechanisms. 5 (2), 200-209 (2012).</li><li>Kroehne, V., Freudenreich, D., Hans, S., Kaslin, J., Brand, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regeneration+of+the+adult+zebrafish+brain+from+neurogenic+radial+glia-type+progenitors.">Regeneration of the adult zebrafish brain from neurogenic radial glia-type progenitors.</a> Development. 138 (22), 4831-4841 (2011).</li><li>Marz, M., Schmidt, R., Rastegar, S., Strahle, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regenerative+response+following+stab+injury+in+the+adult+zebrafish+telencephalon.">Regenerative response following stab injury in the adult zebrafish telencephalon.</a> Developmental Dynamics. 240 (9), 2221-2231 (2011).</li><li>Ayari, B., Elhachimi, K. H., Yanicostas, C., Landoulsi, A., Soussi-Yanicostas, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prokineticin+2+expression+is+associated+with+neural+repair+of+injured+adult+zebrafish+telencephalon.">Prokineticin 2 expression is associated with neural repair of injured adult zebrafish telencephalon.</a> Journal of Neurotrauma. , (2010).</li><li>Skaggs, K., Goldman, D., Parent, J. 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A., Talbot, 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=Glial+cell+development+and+function+in+zebrafish.">Glial cell development and function in zebrafish.</a> Cold Spring Harbor Perspectives in Biology. 7 (2), a020586 (2014).</li><li>Obermann, 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=The+Surface+Proteome+of+Adult+Neural+Stem+Cells+in+Zebrafish+Unveils+Long-Range+Cell-Cell+Connections+and+Age-Related+Changes+in+Responsiveness+to+IGF.">The Surface Proteome of Adult Neural Stem Cells in Zebrafish Unveils Long-Range Cell-Cell Connections and Age-Related Changes in Responsiveness to IGF.</a> Stem Cell Reports. 12 (2), 258-273 (2019).</li><li>Progatzky, F., Dallman, M. J., Lo Celso, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+seeing+to+believing:+labelling+strategies+for+in+vivo+cell-tracking+experiments.">From seeing to believing: labelling strategies for in vivo cell-tracking experiments.</a> Interface Focus. 3 (3), 20130001 (2013).</li><li>Kusumanto, Y. H., 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=Improvement+of+in+vivo+transfer+of+plasmid+DNA+in+muscle:+comparison+of+electroporation+versus+ultrasound.">Improvement of in vivo transfer of plasmid DNA in muscle: comparison of electroporation versus ultrasound.</a> Drug Delivery. 14 (5), 273-277 (2007).</li><li>Zou, M., De Koninck, P., Neve, R. L., Friedrich, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+gene+transfer+into+the+adult+zebrafish+brain+by+herpes+simplex+virus+1+(HSV-1)+and+electroporation:+methods+and+optogenetic+applications.">Fast gene transfer into the adult zebrafish brain by herpes simplex virus 1 (HSV-1) and electroporation: methods and optogenetic applications.</a> Frontiers in Neural Circuits. 8 (41), (2014).</li><li>Van Tendeloo, V. F., 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=Highly+efficient+gene+delivery+by+mRNA+electroporation+in+human+hematopoietic+cells:+superiority+to+lipofection+and+passive+pulsing+of+mRNA+and+to+electroporation+of+plasmid+cDNA+for+tumor+antigen+loading+of+dendritic+cells.">Highly efficient gene delivery by mRNA electroporation in human hematopoietic cells: superiority to lipofection and passive pulsing of mRNA and to electroporation of plasmid cDNA for tumor antigen loading of dendritic cells.</a> Blood. 98 (1), 49-56 (2001).</li><li>Mars, T., 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=Electrotransfection+and+lipofection+show+comparable+efficiency+for+in+vitro+gene+delivery+of+primary+human+myoblasts.">Electrotransfection and lipofection show comparable efficiency for in vitro gene delivery of primary human myoblasts.</a> The Journal of Membrane Biology. 248 (2), 273-283 (2015).</li><li>Barbosa, J. S., Di Giaimo, R., Gotz, M., Ninkovic, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+in+vivo+imaging+of+adult+neural+stem+cells+in+the+zebrafish+telencephalon.">Single-cell in vivo imaging of adult neural stem cells in the zebrafish telencephalon.</a> Nature Protocols. 11 (8), 1360-1370 (2016).</li><li>Di Giaimo, 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=The+Aryl+Hydrocarbon+Receptor+Pathway+Defines+the+Time+Frame+for+Restorative+Neurogenesis.">The Aryl Hydrocarbon Receptor Pathway Defines the Time Frame for Restorative Neurogenesis.</a> Cell Reports. 25 (12), 3241-3251 (2018).</li><li>Breunig, C. T., 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=One+step+generation+of+customizable+gRNA+vectors+for+multiplex+CRISPR+approaches+through+string+assembly+gRNA+cloning+(STAgR).">One step generation of customizable gRNA vectors for multiplex CRISPR approaches through string assembly gRNA cloning (STAgR).</a> PLoS One. 13 (4), e0196015 (2018).</li><li>Barbosa, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> In vivo single cell analysis reveals distinct behavior of neural stem and progenitor cells in homeostasis and regeneration in the adult brain. , (2014).</li><li>Kelsh, R. N., 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=Zebrafish+pigmentation+mutations+and+the+processes+of+neural+crest+development.">Zebrafish pigmentation mutations and the processes of neural crest development.</a> Development. 123, 369-389 (1996).</li><li>Torper, O., 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=In+Vivo+Reprogramming+of+Striatal+NG2+Glia+into+Functional+Neurons+that+Integrate+into+Local+Host+Circuitry.">In Vivo Reprogramming of Striatal NG2 Glia into Functional Neurons that Integrate into Local Host Circuitry.</a> Cell Reports. 12 (3), 474-481 (2015).</li><li>Nguyen, L. T., Atobe, K., Barichello, J. M., Ishida, T., Kiwada, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complex+formation+with+plasmid+DNA+increases+the+cytotoxicity+of+cationic+liposomes.">Complex formation with plasmid DNA increases the cytotoxicity of cationic liposomes.</a> Biological and Pharmaceutical Bulletin. 30 (4), 751-757 (2007).</li><li>Chapouton, P., Godinho, L., Detrich, H. W., Westerfield, M., Zon, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Neurogenesis. 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Authors have nothing to disclose.

This electroporation protocol is a reliable in vivo method of labelling individual ependymoglial cells. The protocol may need a further adaptation to label other cell types such as neurons or oligodendrocytes. To achieve successful labelling, plasmids containing different promoters can be used. Chicken-beta actin promoter, eF1alpha, CMV and ubiquitin promoter have been previously used to drive the expression of different transgenes in ependymoglia and their progeny23. However, different kinetics o...

Zebrafish are excellent animal models to examine brain regeneration after a stab wound injury. In comparison to mammals, on the evolutionary ladder, less evolved species such as zebrafish generally show higher rates of constitutive neurogenesis and broader areas of adult neural stem cell residence, leading to constant generation of new neurons throughout most brain areas in the adult life. This feature appears to correlate with significantly higher regenerative capacity of zebrafish in comparison to mammals1, as zebrafish have remarkable potential to efficiently generate new neurons in most brain injury models studied2,3,4,5,6,7,8. Here, the zebrafish telencephalon is studied, since it is a brain area with prominent neurogenesis in adulthood. These zones of adult neurogenesis are homologous to neurogenic zones in the adult mammalian brain9,10,11.
Abundant neurogenic areas in the zebrafish telencephalon are present due to the existence of radial glia like cells or ependymoglia cells. Ependymoglial cells act as resident adult neural stem cells and are responsible for generation of new neurons in both the intact and regenerating brain3,5. Lineage tracing experiments have shown that ventricular ependymoglia react to injury, then proliferate and generate new neuroblasts that migrate to the lesion site5. Due to the everted nature of zebrafish telencephalon, ependymoglial cells line the ventricular surface and build the ventral ventricular wall. The dorsal ventricular wall is formed by a dorsal ependymal cell layer (Figure 1A). Importantly, zebrafish ependymoglia embody the characteristics of both mammalian radial glia and ependymal cells. Long radial processes are a typical feature of radial glia cells, whereas cellular extensions and tight junctions (as well as their ventricular positions) are typical features of ependymal cells12,13,14. Therefore, these cells are referred to as ependymoglial cells.
To follow in vivo behavior of single ependymoglial cells during regeneration, they need to be reliably labeled. Various methods of in vivo cell labeling for fluorescent microscopy have been previously described, such as endogenous reporters or lipophilic dyes15. These methods, in contrast to electroporation, may require longer periods of time and often do not offer the possibility of single cell labeling or permanent long-term tracing. Electroporation, however (besides single cell labeling), offers the possibility of introducing new DNA into the host cell. Moreover, compared to other methods of DNA transfer into the cells, electroporation has been demonstrated to be one of the most efficient methods16,17,18,19.
Presented here is an electroporation protocol that has been refined for the purpose of labeling single ependymoglial cells in the adult zebrafish telencephalon. This protocol allows for the labelling of single ependymoglial cells in order to follow them over a long-term period20 or to manipulate specific pathways in a cell-autonomous manner21,22.

<table>
	<tbody>
		<tr>
			<td>Reagent/Material</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fast Green</td>
			<td>Sigma-Aldrich</td>
			<td>F7258-25G</td>
			<td>For coloring plasmid solution</td>
		</tr>
		<tr>
			<td>MS222</td>
			<td>Sigma-Aldrich</td>
			<td>A5040-25G</td>
			<td>MS222 should be stored at RT (up to two weeks) and protected from light</td>
		</tr>
		<tr>
			<td>Ultrasound gel</td>
			<td>SignaGel, Parker laboratories INC.</td>
			<td>15-60</td>
			<td>Electrode Gel</td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Air pump</td>
			<td>TetraTec APS 50, 10l-60l</td>
			<td></td>
			<td>Can be bought in the pet shops</td>
		</tr>
		<tr>
			<td>BTX Tweezertrodes Electrodes</td>
			<td>Platinum Tweezertrode, BTX Harvard Apparatus</td>
			<td>45-0486</td>
			<td>1mm diameter</td>
		</tr>
		<tr>
			<td>Electroporation device</td>
			<td>BTX ECM830 Square Wave Electroporation System, BTX Harvard Apparatus</td>
			<td>45-0662</td>
			<td></td>
		</tr>
		<tr>
			<td>Injection device</td>
			<td>FemtoJet 4i, Eppendorf</td>
			<td>5252000013</td>
			<td></td>
		</tr>
		<tr>
			<td>Standard Wall Borosillicate Glass Capillary</td>
			<td>Warner Instruments</td>
			<td>64-0766</td>
			<td>Model No: G100-4</td>
		</tr>
		<tr>
			<td>Microloader tips</td>
			<td>Eppendorf</td>
			<td>5242956003</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro-knife</td>
			<td>Fine Science Tools</td>
			<td>10056-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Joystick micromanipulator</td>
			<td>Narishige Japan</td>
			<td>MN - 151</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle holder</td>
			<td>FemtoJet 4i, Eppendorf</td>
			<td>5252000013</td>
			<td>Needle holder comes together with the injection device</td>
		</tr>
		<tr>
			<td>Needle pulling device</td>
			<td>Narishige Japan</td>
			<td>Model No: PC-10</td>
			<td>The PC-10 was discontinued by Narishige in 2017 and replaced by the PC-100</td>
		</tr>
		<tr>
			<td>Petri dishes</td>
			<td>Greiner Bio-One International</td>
			<td>633161</td>
			<td></td>
		</tr>
	</tbody>
</table>

electroporation method for in vivo delivery of plasmid dna in the adult zebrafish telencephalon

Electroporation is a transfection method in which an electrical field is applied to cells to create temporary pores in a cell membrane and increase its permeability, thereby allowing different molecules to be introduced to the cell. In this paper, electroporation is used to introduce plasmids to ependymoglial cells, which line the ventricular zone of the adult zebrafish telencephalon. A fraction of these cells shows stem cell properties and generates new neurons in the zebrafish brain; therefore, studying their behavior is essential to determine their roles in neurogenesis and regeneration. The introduction of plasmids via electroporation enables long-term labeling and tracking of a single ependymoglial cell. Furthermore, plasmids such as Cre recombinase or Cas9 can be delivered to single ependymoglial cells, which enables gene recombination or gene editing and provides a unique opportunity to assess the cell&#8217;s autonomous gene function in a controlled, natural environment. Finally, this detailed, step-by-step electroporation protocol is used to obtain successful introduction of plasmids into a large number of single ependymoglial cells.

The described electroporation method allows delivery of plasmid DNA into ependymoglial cells, which are located superficially in the zebrafish telencephalon and just under the dorsal ependymal cell layer (Figure 1A).
If the result of electroporation is positive, labeled single ependymoglial cells (red cells in Figure 2A,B) can be observed among other ependymoglial cells (white in <s...

Watch this Scientific Journal Video about Electroporation Method for In Vivo Delivery of Plasmid DNA in the Adult Zebrafish Telencephalon at JoVE.com

Electroporation Method for In Vivo Delivery of Plasmid DNA in the Adult Zebrafish Telencephalon

Presented here is an electroporation method for plasmid DNA delivery and ependymoglial cell labeling in the adult zebrafish telencephalon. This protocol is a quick and efficient method to visualize and trace individual ependymoglial cells and opens up new possibilities to apply electroporation to a broad range of genetic manipulations.

Electroporation is a transfection method in which an electrical field is applied to cells to create temporary pores in a cell membrane and increase its ...

This protocol allows the labeling of individual ependymoglial cells in the zebrafish telencephalon to enable their long-term monitoring, as well as the manipulation of specific pathways in a cell-autonomous manner. The main advantage of this technique is that it allows single cell labeling in fast and efficient way, as well as gene editing and signaling pathway manipulation in cell-autonomous manner. This method allows the investigation of basic cell biology questions, for example, about cell delamination, the maintenance of epithelial homeostasis, and the symmetry of cell division.Begin by using a needle-pulling apparatus to prepare glass capillaries. Use microloader tips to fill a prepared glass capillary with ten microliters of plasmid solution. Then press menu change capillary"on the injection device to allow the needle to be loaded into the needle holder.Then switch the injection device from change capillary to inject mode. Then, using a stereomicroscope with a four times magnification, and Finden forceps, cut only the tip of the capillary. Then apply pressure to the foot pedal to confirm that the plasmid solutions runs easily out of the needle without hindrance.When the needle is ready, transfer a zebrafish from the husbandry tank to a container of anesthetic solution. And wait a few minutes until the movement of the gills subsides. Press the sedated fish dorsal side up onto a pre-wetted sponge under the stereomicroscope, and use a stainless steel dissecting microknife with a 40 millimeter cutting edge and a 0.5 millimeter thickness to carefully create a small hole in the fish skull at the posterior side of the telencephalon, just next to the border of the optic tectum.Tilt the fish as necessary and orient the tip of the glass capillary towards the skull in the correct angle to facilitate penetration of the capillary tip through the hole. Then, very carefully insert the tip of the capillary into the hole through the dorsal ependymal cell layer, until it reaches the telencephalic ventricle, and apply pressure to the foot pedal for about 10 seconds to deliver approximately 1 microliter of the plasmid solution. The success of the delivery can be confirmed by observing the spreading of the green liquid throughout the ventricle.Cover the fish telencephalon with a small amount of ultrasound gel. For electroporation of the plasmid injected animal, remove the sponge from the injection set-up and immerse the inner side of the electrotips into ultrasound gel. Position the fish head between the electrodes, with the positive electrode at the ventral side of the head and the negative electrode on the dorsal side.Then, while still holding the fish's body in the sponge, press the electrodes gently and precisely against the telencephalon and administer the current with the foot pedal, holding the electrodes in place until all five pulses are finished. If the electroporation is successful, plasmid labeled single ependymoglial cells can be observed among the non-plasmid labeled ependymoglial cells. Depending on the efficiency of the electroporation process, a higher or lower number of ependymoglial cells may be labeled.Nevertheless, the demonstrated protocol yields a higher number of labeled cells than previously published protocols. Note that the highest density of labeled cells tends to emerge mostly at the inner ventricular side of both hemispheres due to the way in which the injected plasmid liquid distributes between the hemispheres. In this video, one hemisphere of the zebrafish telencephalon is presented in 3D, where the ependymoglial cells with radio-processes, are in magenta when observed from the side.Through co-electroporation with another plasmid that labels nuclei, cell division of ependymoglial cells can be observed. Unsuccessful electroporation results in very low number or no labeled ependymoglial cells. Dorsal ependymal cells, however, are the most likely to be labeled.Their soma is larger in cuboid and they do not possess radio-elongated processes as evident from a side view of the ependymoglial cell layer. tdTomato-mem labeled cells are most likely ependymal cells, which are located above the layer of ependymoglia. In contrast, the introduction of a tdTomato-mem expressing plasmid to individual ependmyoglial cells results in tdTomato-mem expression in addition to the initial cell labeling.The most important things to remember are to cut only the tip of the capillary and to penetrate the ependymal layer while injecting so that the liquid spreads throughout the ventricle. This technique enables the long-term monitoring of single ependymoglial cells through in vivo imaging, and therefore establishing their role in brain regeneration as well as their vast in vivo genetic link.

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Developmental Biology

9.6K visualizações.  Helmholtz Zentrum München. Este protocolo permite a rotulagem de células ependymoglial individuais no telencephalon de zebrafish para permitir seu monitoramento a longo prazo, bem como a manipulação de caminhos específicos de forma autônoma celular. A principal vantagem dessa técnica é que ela permite a rotulagem de células únicas de forma rápida e eficiente, bem como a edição de genes e a manipulação da via de sinalização de forma autônoma celular. Este método permite a investigação de questões b?...