We appreciate the support provided by William Archer and the Notre Dame Integrated Imaging Facility. Special thanks are directed to the Freimann Life Sciences technicians for their continuous help and their care and husbandry of the zebrafish. This study was supported by grants from the National Eye Institute of NIH to DRH (R01-EY018417, R01-EY024519) and the Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN.

Note: Zebrafish were raised and maintained in the Notre Dame Zebrafish facility in the Freimann Life Sciences Center. The methods described in this manuscript are approved by the University of Notre Dame Animal Care and Use Committee and are in compliance with the statement for the use of animals in vision research by the Association for Research in Vision and Ophthalmology.
1. Solutions
<ol>
	<li>Prepare 70% ethanol to sterilize the tissue culture hood and any equipment/reagents that are tr...

<ol>
	<li>Fausett, B. V., Goldman, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+alpha1+tubulin-expressing+Muller+glia+in+regeneration+of+the+injured+zebrafish+retina.">A role for alpha1 tubulin-expressing Muller glia in regeneration of the injured zebrafish retina.</a> J.Neurosci. 26 (23), 6303-6313 (2006).</li><li>Kassen, S. 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=Time+course+analysis+of+gene+expression+during+light-induced+photoreceptor+cell+death+and+regeneration+in+albino+zebrafish.">Time course analysis of gene expression during light-induced photoreceptor cell death and regeneration in albino zebrafish.</a> Dev.Neurobiol. 67 (8), 1009-1031 (2007).</li><li>Vihtelic, T. S., Hyde, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-induced+rod+and+cone+cell+death+and+regeneration+in+the+adult+albino+zebrafish+(Danio+rerio)+retina.">Light-induced rod and cone cell death and regeneration in the adult albino zebrafish (Danio rerio) retina.</a> J.Neurobiol. 44 (3), 289-307 (2000).</li><li>Bernardos, R. L., Barthel, L. K., Meyers, J. R., Raymond, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Late-stage+neuronal+progenitors+in+the+retina+are+radial+Muller+glia+that+function+as+retinal+stem+cells.">Late-stage neuronal progenitors in the retina are radial Muller glia that function as retinal stem cells.</a> J.Neurosci. 27 (26), 7028-7040 (2007).</li><li>Nelson, C. M., Ackerman, K. M., O'Hayer, P., Bailey, T. J., Gorsuch, R. A., Hyde, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+necrosis+factor-alpha+is+produced+by+dying+retinal+neurons+and+is+required+for+Muller+glia+proliferation+during+zebrafish+retinal+regeneration.">Tumor necrosis factor-alpha is produced by dying retinal neurons and is required for Muller glia proliferation during zebrafish retinal regeneration.</a> J.Neurosci. 33 (15), 6524-6539 (2013).</li><li>Lahne, M., Li, J., Marton, R. M., Hyde, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Actin-Cytoskeleton-+and+Rock-Mediated+INM+Are+Required+for+Photoreceptor+Regeneration+in+the+Adult+Zebrafish+Retina.">Actin-Cytoskeleton- and Rock-Mediated INM Are Required for Photoreceptor Regeneration in the Adult Zebrafish Retina.</a> J.Neurosci. 35 (47), 15612-15634 (2015).</li><li>Nagashima, M., Barthel, L. K., Raymond, P. 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+self-renewing+division+of+zebrafish+Muller+glial+cells+generates+neuronal+progenitors+that+require+N-cadherin+to+regenerate+retinal+neurons.">A self-renewing division of zebrafish Muller glial cells generates neuronal progenitors that require N-cadherin to regenerate retinal neurons.</a> Development. 140 (22), 4510-4521 (2013).</li><li>Sauer, M. E., Walker, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radioautographic+study+of+interkinetic+nuclear+migration+in+the+neural+tube.">Radioautographic study of interkinetic nuclear migration in the neural tube.</a> Proc.Soc.Exp.Biol.Med. 101 (3), 557-560 (1959).</li><li>Pearson, R. A., Luneborg, N. L., Becker, D. L., Mobbs, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gap+junctions+modulate+interkinetic+nuclear+movement+in+retinal+progenitor+cells.">Gap junctions modulate interkinetic nuclear movement in retinal progenitor cells.</a> J.Neurosci. 25 (46), 10803-10814 (2005).</li><li>Baye, L. M., Link, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interkinetic+nuclear+migration+and+the+selection+of+neurogenic+cell+divisions+during+vertebrate+retinogenesis.">Interkinetic nuclear migration and the selection of neurogenic cell divisions during vertebrate retinogenesis.</a> J.Neurosci. 27 (38), 10143-10152 (2007).</li><li>Del Bene, F., Wehman, A. M., Link, B. A., Baier, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+neurogenesis+by+interkinetic+nuclear+migration+through+an+apical-basal+notch+gradient.">Regulation of neurogenesis by interkinetic nuclear migration through an apical-basal notch gradient.</a> Cell. 134 (6), 1055-1065 (2008).</li><li>Norden, C., Young, S., Link, B. A., Harris, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Actomyosin+is+the+main+driver+of+interkinetic+nuclear+migration+in+the+retina.">Actomyosin is the main driver of interkinetic nuclear migration in the retina.</a> Cell. 138 (6), 1195-1208 (2009).</li><li>Becker, D. L., 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=Multiphoton+imaging+of+chick+retinal+development+in+relation+to+gap+junctional+communication.">Multiphoton imaging of chick retinal development in relation to gap junctional communication.</a> J.Physiol. 585 (Pt 3), 711-719 (2007).</li><li>Surzenko, N., Crowl, T., Bachleda, A., Langer, L., Pevny, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SOX2+maintains+the+quiescent+progenitor+cell+state+of+postnatal+retinal+Muller+glia.">SOX2 maintains the quiescent progenitor cell state of postnatal retinal Muller glia.</a> Development. 140 (7), 1445-1456 (2013).</li><li>Nickerson, P. E., 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+and+analysis+of+postnatal+mouse+retinal+development.">Live imaging and analysis of postnatal mouse retinal development.</a> BMC Dev.Biol. 13, 24 (2013).</li><li>Suzuki, S. C., Bleckert, A., Williams, P. R., Takechi, M., Kawamura, S., Wong, R. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cone+photoreceptor+types+in+zebrafish+are+generated+by+symmetric+terminal+divisions+of+dedicated+precursors.">Cone photoreceptor types in zebrafish are generated by symmetric terminal divisions of dedicated precursors.</a> Proc.Natl.Acad.Sci.U.S.A. 110 (37), 15109-15114 (2013).</li><li>Johnson, T. V., Martin, K. 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The authors have nothing to disclose.

Studies investigating the mechanisms governing regeneration of the damaged adult zebrafish retina predominantly used immunocytochemical methods5,25,26,27,28,29,30. Establishing conditions to culture retinal explants and to perform live-cell imaging on phenomena, such as INM, provide us a tec...

Unlike humans, zebrafish (Danio rerio) exhibit a robust regeneration response upon cell death of retinal neurons1,2,3,4. Tumor necrosis factor &#945;, a signaling molecule that is released from dying retinal neurons induces M&#252;ller glia residing in the basal Inner Nuclear Layer (INL) of the retina, to proliferate5 and produce neuronal progenitor cells that continue to proliferate before differentiating into the neuronal cell types that died2,3,4. During the proliferative phase of the regeneration response, the nuclei of M&#252;ller glia and their derived neuronal progenitor cells undergo a repetitive migratory pattern in phase with the cell cycle (Interkinetic Nuclear Migration, INM)6,7. Nuclei positioned in the basal INL replicate their DNA before migrating to the Outer Nuclear Layer (ONL) where they divide before the arising nuclei return basally to the INL. This process was first described during neuroepithelial development using histological methods, while live-cell imaging approaches later confirmed the interpretation by Sauer8,9,10,11,12. Both histochemical and live-cell imaging approaches have been used to determine mechanisms underlying INM and its function in developing neuroepithelia including the retina9,11,12,13. However, the mechanisms governing INM in the adult regenerating retina have not been studied in much detail6,7. Live-cell imaging will be an invaluable approach to advance our knowledge of the signaling pathways that control INM in the adult regenerating retina.
Until recently, live-cell imaging of INM in the retina was limited to either live zebrafish embryos or to embryonic chick or postnatal mouse retinal explants9,10,11,12,14,15,16. While retinal explants from adult animals of a variety of species including mouse, rat and zebrafish have been utilized for different cell biological approaches17,18,19,20, live-cell imaging experiments using retinal explants have been restricted to brief periods of time and have not been executed continuously over several hours21,22. Here, we describe a detailed protocol to culture light-damaged adult zebrafish retinas to perform live-cell imaging experiments monitoring INM using multi-photon microscopy6. Live-cell imaging approaches are advantageous over immunohistochemical methods when investigating the mechanisms controlling INM, as the dynamics of INM, e.g., velocities might be affected rather than the location of mitosis, which would potentially not be detected using immunocytochemistry.
In the future, this method has also the potential to be modified to study other dynamic processes during retinal regeneration, such as phagocytosis of dying photoreceptors by M&#252;ller glia or the behavior of microglia.

<table border="0" cellpadding="0" cellspacing="0" width="876">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:491px;">Dumont forceps size #5</td>
			<td style="width:201px;">World precision instruments</td>
			<td align="right" style="width:113px;">14098</td>
			<td style="width:72px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dumont forceps size #5, 45&#176; angle</td>
			<td>World precision instruments</td>
			<td align="right">14101</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">McPherson-Vannas scissors</td>
			<td>World precision instruments</td>
			<td align="right">501233</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fluordishes</td>
			<td>World precision instruments</td>
			<td>FD35-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Stereomicroscope</td>
			<td>Nikon&#160;</td>
			<td>SMZ-1B</td>
			<td>similar type of dissection stereomicroscope will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Biological Safety Cabinet class type A2</td>
			<td>Labconco</td>
			<td></td>
			<td>equivalent type will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">tissue culture incubator</td>
			<td>Thermoscientific</td>
			<td>HEPA-class 100</td>
			<td>equivalent type will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sylvania fluorescent lamps OSFP5835HOECO</td>
			<td>Bulbtronics</td>
			<td align="right">31850</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.2 &#181;m pore-size Acrodisc syringe filter</td>
			<td>VWR</td>
			<td align="right">4192</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10 ml Luer-lok syringe</td>
			<td>VWR</td>
			<td>BD309604</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">60 ml Luer-lok syringe</td>
			<td>VWR</td>
			<td>BD309653</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">NaHCO3</td>
			<td>FischerScientific</td>
			<td>S233-500</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">CaCl2</td>
			<td>ThermoScientific</td>
			<td>C79-500</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">MgCl2</td>
			<td>EMD Millipore</td>
			<td align="right">5980</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">HBSS w/o Ca2+/Mg2+, w/o phenol red, Gibco</td>
			<td>ThermoScientific</td>
			<td>14175-095</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MEM w/o phenol red, Gibco</td>
			<td>ThermoScientific</td>
			<td>5100-038</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Horse serum, heat-inactivated</td>
			<td>ThermoScientific</td>
			<td>26050-070</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">penicillin/streptomycin</td>
			<td>VWR</td>
			<td>16777-164</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultrapure low melting point agarose</td>
			<td>ThermoScientific</td>
			<td>16520-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ethanol, absolute</td>
			<td>ThermoScientific</td>
			<td>BP2818-4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2-phenoxyethanol</td>
			<td>Sigma</td>
			<td align="right">77699</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Corning Cell-Tak cell and tissue adhesive&#160;</td>
			<td>VWR</td>
			<td align="right">354240</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">refractive index liquid&#160;</td>
			<td>Cargille Lab</td>
			<td>1803Y</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nikon A1 multiphoton microscope equipped with a MaiTai infrared laser</td>
			<td>Nikon</td>
			<td></td>
			<td>equivalent system will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">40x Apo long-distance water immersion objective (N.A. 1.15)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">environmental chamber equipped with insert for 35 mm petridishes</td>
			<td>Okolab</td>
			<td></td>
			<td>equivalent system will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NIS analysis software</td>
			<td>Nikon</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

culture of adult transgenic zebrafish retinal explants for live-cell imaging by multiphoton microscopy

An endogenous regeneration program is initiated by M&#252;ller glia in the adult zebrafish (Danio rerio) retina following neuronal damage and death. The M&#252;ller glia re-enter the cell cycle and produce neuronal progenitor cells that undergo subsequent rounds of cell divisions and differentiate into the lost neuronal cell types. Both M&#252;ller glia and neuronal progenitor cell nuclei replicate their DNA and undergo mitosis in distinct locations of the retina, i.e. they migrate between the basal Inner Nuclear Layer (INL) and the Outer Nuclear Layer (ONL), respectively, in a process described as Interkinetic Nuclear Migration (INM). INM has predominantly been studied in the developing retina. To examine the dynamics of INM in the adult regenerating zebrafish retina in detail, live-cell imaging of fluorescently-labeled M&#252;ller glia/neuronal progenitor cells is required. Here, we provide the conditions to isolate and culture dorsal retinas from Tg[gfap:nGFP]mi2004 zebrafish that were exposed to constant intense light for 35 h. We also show that these retinal cultures are viable to perform live-cell imaging experiments, continuously acquiring z-stack images throughout the thickness of the retinal explant for up to 8 h using multiphoton microscopy to monitor the migratory behavior of gfap:nGFP-positive cells. In addition, we describe the details to perform post-imaging analysis to determine the velocity of apical and basal INM. To summarize, we established conditions to study the dynamics of INM in an adult model of neuronal regeneration. This will advance our understanding of this crucial cellular process and allow us to determine the mechanisms that control INM.

The isolation of the retina according to the procedure outlined in the schematic in Figure 1 allows the culturing of a flattened dorsal retina from light-damaged adult Tg[gfap:nGFP]mi2004 zebrafish over a period of at least 24 h in a 5% CO2/air environment. These flat-mounted retinal explants can be used to image focal planes at deep tissue levels. An example is M&#252;ller glia/neuronal progenitor cell nuclei labeled with GFP from the M&#25...

Watch this Scientific Journal Video about Culture of Adult Transgenic Zebrafish Retinal Explants for Live-cell Imaging by Multiphoton Microscopy at JoVE.com

Culture of Adult Transgenic Zebrafish Retinal Explants for Live-cell Imaging by Multiphoton Microscopy

Zebrafish retinal regeneration has mostly been studied using fixed retinas. However, dynamic processes such as interkinetic nuclear migration occur during the regenerative response and require live-cell imaging to investigate the underlying mechanisms. Here, we describe culture and imaging conditions to monitor Interkinetic Nuclear Migration (INM) in real-time using multiphoton microscopy.

An endogenous regeneration program is initiated by M&#252;ller glia in the adult zebrafish (Danio rerio) retina following neuronal damage and death. The ...

The overall goal of this isolation procedure is to enable live cell imaging of the proliferating cells that are undergoing interkinetic nuclear migration in the retinal explant cultures from damaged zebrafish. This method can answer key questions in retinal regeneration, such as what mechanisms drive interkinetic nuclear migration or whether Muller glia in a renal progenitor cell interkinetic nuclear migration are similarly regulated. The main advantage of this technique is that the dynamic behavior of the proliferating cells undergoing interkinetic nuclear migration during regeneration can be monitored, which permits the investigation of cell cycle stage specific mechanisms.Though this method can provide insight into interkinetic nuclear migration, it can also be applied to other retinal research areas, such as investigating microglial behavior or Muller glia phagocytosis of dying neurons. Begin this procedure by transferring the zebrafish onto a dry paper towel. Then, remove one of the eyes with a pair of curved forceps and transfer it onto a FluoroDish.Under a stereo microscope, orient the eye with the pupil facing the coverslip of the FluoroDish so that the optic nerve on the back of the eye is visible. Then, remove the optic nerve as close to the back of the eye as possible. In addition, remove the connective tissue outside of the eye.Hold the eye between its nasal and temporal sides with a pair of forceps while making an incision at the optic stock by piercing through the lamina cribrosa with one scissor blade and cutting along both the nasal and temporal sides of the eye. Next, pull the dorsal and the ventral sides of the retina apart. Remove the sclera from the dorsal retina with one pair of forceps while holding the lens that is connected to the retina with a second pair of forceps.Following that, remove the lens and the vitreous without damaging the retina. Then, flatten the retina with the ganglion cell layer facing the coverslip of the FluoroDish. Afterward, surround the retina with 10 microliters of 1%low melting point agarose.Make sure that the retina is not lifted by the liquid agarose because even slight elevation might affect the ability to focus through the tissue. If lifting is observed, use a pipette to remove the agarose. It is critical that the agarose does not lift the tissue from the coverslip, as this reduces the ability to obtain quality images.Repeat this procedure several times before adding 1%low melting point agarose to cover the entire FluoroDish. Once the agarose has solidified, add 1.5 milliliters of culture medium to the tissue. In the image acquisition software, open A1 MP GUI TI pad, A1 compact GUI, and ND acquisition windows.For multi photon imaging, ensure that the IRNDD option is chosen in A1 compact GUI window. Then, in the setting field, select IRDM for the first dichroic mirror and check that the band pass filter is set to 525 to 50 to acquire GFP fluorescence. Next, switch on the IR laser in the A1 MP GUI window.It will take a few minutes for the laser to be ready. After that, set the wavelength to 910 nanometers to excite GFP flourescence and align the laser by clicking the auto-alignment button. After placing the retinal culture on the multiphoton microscope stage, ensure that the room and equipment lights are switched off before opening the shutter to avoid overexposure of the photo multiplier tube.To reduce noise levels, house the microscope in a darkened environment. Acquire images of a field of view of 300 by 300 pixels at a zoom of two, which are set in the scan area window and a pixel dwelling time of 4.8 microseconds per pixel chosen in the A1 compact GUI window. Roughly set up the laser power by changing the acquisition area in the A1 MP GUI window and the gain in the A1 compact GUI window.Now, focus on the ganglion cell layer and set the top focal plane of the z stack in the z sub-window within the ND acquisition window. Move the focal plane through the level of the outer nuclear layer, which is characterized by the presence of dimly labeled GFAP and GFP positive cells that are round and enlarged relative to their counterparts in the inner nuclear layer. Set this plane as the bottom of the z stack.Next, set the z step size between 0.7 to one micrometer. To set up the z intensity correction, open the z intensity correction window and choose from ND for setting the z stack range. Then, click on the bottom focal plane in the z intensity correction window and set the laser intensity and gain.Afterward, click the arrow next to the z values in the z intensity correction window to confirm the settings that are subsequently shown under device settings in the z intensity correction window for the chosen focal plane. Repeat the process for the middle and top planes, increasing the laser power and gain. Set the acquisition area in the A1 MP GUI window and avoid selecting an acquisition area larger than 15 and a gain higher than 126 at the start of imaging to circumvent photo bleaching and increased noise levels.Subsequently, choose relative intensity correction in the z intensity correction window. In the time series sub window of the ND acquisition window, set the duration to 8 hours and the interval to no delay. Then, click the run z correction in the z stack sub window of the ND acquisition window to acquire 3D time series.In this procedure, crop a region that contains a dividing GFAP and GFP positive nucleus. Choose a cropped region that contains at least one nucleus that does not undergo INM in order to set a reference point to subsequently measure the distances that the dividing nucleus migrated in relation to the basal INL. It helps to prepare a 3D reconstruction.Using the show slices view function, generate orthogonal projections. Subsequently, change the mode from slice to maximum intensity projection. Then, turn off the XY view of the orthogonal maximum projection.Depending on the orientation at which the migrating and dividing nucleus is best visible, also turn off either the XZ or the YZ view. Click on the remaining image with the right mouse button and extract the XZ or YZ image series with the create new document from this view function. If necessary, rotate the image.Using the manual measurement function, draw a horizontal line across the image at the bottom level of the nucleus that remains in the basal INL and does not undergo INM. Measure the distance between the reference line and the basal point of the migrating nucleus for the time series using the line measurement tool in the analysis software. Shown here is the maximum YZ projection of a z stack image series of the retinal explants at different time points of the time lapse recording acquired by multiphoton microscopy.Using the line tool under the manual measurement function, a horizontal line was placed at the level of the reference cell indicated by a star. A vertical measurement line was positioned starting at the horizontal line and extending to the basal position of the migrating GF AP and GFP positive nucleus. Distance that the cell, F0, measured in the previous figure migrated apically and that the arising daughter cells, D1 and D2, migrated basally in the multi photon time lapse recording.The red line indicates the measurements for which the apical migration velocity was calculated, while the black and gray lines indicate the measurements used to calculate the basal migration velocities for D1 and D2 respectively. The distance was plotted against time in itself for apical migration before the nuclear envelope breakdown and the phase of rapid basal migration for daughter cell D1.Once mastered, the isolation of retinas from three fish can be done in 60 to 90 minutes if it is performed properly. This time excludes the preparation steps.While attempting this procedure, it's important to remember to work as quickly as possible to ensure viability of the retinal explant. It is also critical to mount retinas as flat as possible to enable imaging in deeper tissue layers. After watching this video, you should have a good understanding of how to isolate and mount zebrafish retinas, perform live cell imaging in order to monitor interkinetic nuclear migration and to determine migration velocities.

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JoVE Journal

Developmental Biology

8.4K vistas.  University of Notre Dame. The overall goal of this isolation procedure is to enable live cell imaging of the proliferating cells that are undergoing interkinetic nuclear migration in the retinal explant cultures from damaged zebrafish. This method can answer key questions in retinal regeneration, such as what mechanisms drive interkinetic nuclear migration or whether Muller glia in a renal progenitor cell interkinetic nuclear migration are similarly regulated. The main advantage of this technique is that the dynamic b...