Name: in ovo electroporation in the chicken auditory brainstem
Uploaded: 2017-06-09T13:00:00
Description: Watch this Scientific Journal Video about In Ovo Electroporation in the Chicken Auditory Brainstem at JoVE.com

We would like to thank Drs. Leslayann Schecterson, Yuan Wang, Andres Barria and Mrs. Ximena Optiz-Araya for initial assistance with protocol set-up and for providing plasmids. This work was supported by NIH/NIDCD grant DC013841 (JTS).

All procedures were approved by Northwestern University Institutional Animal Care and Use Committees, and carried out in accordance with the National Institutes of Health Guidelines for the Care and Use of Laboratory Animals.
1. Egg Handling
<ol>
	<li>Purchase fertilized eggs from a local vendor. Store eggs at 13 &#176;C in a refrigerator for no longer than 5 days prior to incubation. Embryo viability significantly decreases after 1 week.</li>
	<li>Swab each egg with 70% ethanol before setti...

<ol>
	<li>Grothe, B., Pecka, M., McAlpine, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+sound+localization+in+mammals.">Mechanisms of sound localization in mammals.</a> Physiol Rev. 90 (3), 983-1012 (2010).</li><li>Anderson, S., 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=Neural+timing+is+linked+to+speech+perception+in+noise.">Neural timing is linked to speech perception in noise.</a> J Neurosci. 30 (14), 4922-4926 (2010).</li><li>Shannon, R. V., 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=Speech+recognition+with+primarily+temporal+cues.">Speech recognition with primarily temporal cues.</a> Science. 270 (5234), 303-304 (1995).</li><li>Carr, C. 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=Evolution+and+development+of+time+coding+systems.">Evolution and development of time coding systems.</a> Curr Opin Neurobiol. 11 (6), 727-733 (2001).</li><li>Carr, C. E., Soares, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolutionary+convergence+and+shared+computational+principles+in+the+auditory+system.">Evolutionary convergence and shared computational principles in the auditory system.</a> Brain Behav Evol. 59 (5-6), 294-311 (2002).</li><li>Rubel, E. W., Parks, T. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organization+and+development+of+brain+stem+auditory+nuclei+of+the+chicken:+tonotopic+organization+of+n.+magnocellularis+and+n.+laminaris.">Organization and development of brain stem auditory nuclei of the chicken: tonotopic organization of n. magnocellularis and n. laminaris.</a> J Comp Neurol. 164 (4), 411-433 (1975).</li><li>Rubel, E. W., Smith, D. J., Miller, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organization+and+development+of+brain+stem+auditory+nuclei+of+the+chicken:+ontogeny+of+n.+magnocellularis+and+n.+laminaris.">Organization and development of brain stem auditory nuclei of the chicken: ontogeny of n. magnocellularis and n. laminaris.</a> J Comp Neurol. 166 (4), 469-489 (1976).</li><li>Schecterson, L. 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=TrkB+downregulation+is+required+for+dendrite+retraction+in+developing+neurons+of+chicken+nucleus+magnocellularis.">TrkB downregulation is required for dendrite retraction in developing neurons of chicken nucleus magnocellularis.</a> J Neurosci. 32 (40), 14000-14009 (2012).</li><li>Chesnutt, C., Niswander, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmid-based+short-hairpin+RNA+interference+in+the+chicken+embryo.">Plasmid-based short-hairpin RNA interference in the chicken embryo.</a> Genesis. 39 (2), 73-78 (2004).</li><li>Oertel, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Encoding+of+timing+in+the+brain+stem+auditory+nuclei+of+vertebrates.">Encoding of timing in the brain stem auditory nuclei of vertebrates.</a> Neuron. 19 (5), 959-962 (1997).</li><li>Cramer, K. S., Fraser, S. E., Rubel, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+origins+of+auditory+brain-stem+nuclei+in+the+chick+hindbrain.">Embryonic origins of auditory brain-stem nuclei in the chick hindbrain.</a> Dev Biol. 224 (2), 138-151 (2000).</li><li>Cramer, K. S., 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=EphA4+signaling+promotes+axon+segregation+in+the+developing+auditory+system.">EphA4 signaling promotes axon segregation in the developing auditory system.</a> Dev Biol. 269 (1), 26-35 (2004).</li><li>Korn, M. J., Cramer, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Windowing+chicken+eggs+for+developmental+studies.">Windowing chicken eggs for developmental studies.</a> J Vis Exp. (8), e306 (2007).</li><li>Sanchez, J. 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=Preparation+and+culture+of+chicken+auditory+brainstem+slices.">Preparation and culture of chicken auditory brainstem slices.</a> J Vis Exp. (49), (2011).</li><li>Jhaveri, S., Morest, D. 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+architecture+in+nucleus+magnocellularis+of+the+chicken+auditory+system+with+observations+on+nucleus+laminaris:+a+light+and+electron+microscope+study.">Neuronal architecture in nucleus magnocellularis of the chicken auditory system with observations on nucleus laminaris: a light and electron microscope study.</a> Neuroscience. 7 (4), 809-836 (1982).</li><li>Matsui, R., Tanabe, Y., Watanabe, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Avian+adeno-associated+virus+vector+efficiently+transduces+neurons+in+the+embryonic+and+post-embryonic+chicken+brain.">Avian adeno-associated virus vector efficiently transduces neurons in the embryonic and post-embryonic chicken brain.</a> PLoS One. 7 (11), e48730 (2012).</li><li>Koppl, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auditory+nerve+terminals+in+the+cochlear+nucleus+magnocellularis:+differences+between+low+and+high+frequencies.">Auditory nerve terminals in the cochlear nucleus magnocellularis: differences between low and high frequencies.</a> J Comp Neurol. 339 (3), 438-446 (1994).</li><li>Hyson, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+analysis+of+interaural+time+differences+in+the+chick+brain+stem.">The analysis of interaural time differences in the chick brain stem.</a> Physiol Behav. 86 (3), 297-305 (2005).</li><li>Jones, T. A., Jones, S. M., Paggett, K. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emergence+of+hearing+in+the+chicken+embryo.">Emergence of hearing in the chicken embryo.</a> J Neurophysiol. 96 (1), 128-141 (2006).</li><li>Saunders, J. C., Coles, R. B., Gates, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+auditory+evoked+responses+in+the+cochlea+and+cochlear+nuclei+of+the+chick.">The development of auditory evoked responses in the cochlea and cochlear nuclei of the chick.</a> Brain Res. 63, 59-74 (1973).</li><li>Woolf, N. K., Ryan, A. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+auditory+function+in+the+cochlea+of+the+mongolian+gerbil.">The development of auditory function in the cochlea of the mongolian gerbil.</a> Hear Res. 13 (3), 277-283 (1984).</li><li>Walsh, E. J., McGee, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Postnatal+development+of+auditory+nerve+and+cochlear+nucleus+neuronal+responses+in+kittens.">Postnatal development of auditory nerve and cochlear nucleus neuronal responses in kittens.</a> Hear Res. 28 (1), 97-116 (1987).</li><li>Uziel, A., Romand, R., Marot, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+cochlear+potentials+in+rats.">Development of cochlear potentials in rats.</a> Audiology. 20 (2), 89-100 (1981).</li></ol>

In ovo electroporation is a method of expressing or knocking down genes of interest in order to analyze in vivo gene function8,9. In the chicken embryo, it is an innovative method for expressing plasmid-encoded genes into different auditory brainstem regions8. To ensure optimal expression, several critical steps are required. First, only inject embryos whose otocysts are clearly visible. If otocysts are not visible the em...

Fast neural encoding of sound is essential for normal auditory functions. These include sound localization abilities1, speech in noise discrimination2, and the comprehension of other behaviorally relevant communication signals3. Analogous neurons located in the auditory brainstem of both avians and mammals are highly specialized for fast neural encoding4. These include the chicken nucleus magnocellularis (NM), the nucleus laminaris (NL) and their mammalian analogs, the anteroventral cochlear nucleus (AVCN) and the medial superior olive (MSO), respectively5. However, developmental mechanisms regulating fast neural encoding are poorly understood in the auditory brainstem. Therefore, it is advantageous to study specific genes that are responsible for fast neural encoding in order to better understand their expression, regulation and function in auditory development.
The developing chicken embryo is an effective and well-established research tool to study basic biological questions of auditory system development6,7. Recent molecular advances have addressed these biological questions in the developing chicken embryo by expressing or knocking down genes of interest in order to analyze in vivo gene function8,9. Investigating the regulatory role of specific genes is a significant advancement in understanding pathologies associated with auditory deficits. Here, we present in ovo electroporation of plasmid-encoded genes into the chicken auditory brainstem where fast neural encoding of sound occurs10. By targeting auditory neural progenitor regions associated with rhombomeres 5 and 611,12 (R5/R6), we show spatial control of plasmid transfection in NM and NL. In addition, we show temporal regulation of expression by adopting a tet-on vector system. This is a drug inducible procedure that expresses the genes of interest in the presence of doxycycline (Dox)8.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Fertilized white leghorn chicken eggs</td>
			<td>Sunnyside Inc. (Beaver Dam, WI)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Picospritzer</td>
			<td>Parker Hannifin</td>
			<td>052-0500-900</td>
			<td>Picospritzer III, single or dual channel</td>
		</tr>
		<tr>
			<td>Current/voltage stimulator</td>
			<td>Grass Technologies</td>
			<td>SD9</td>
			<td>SD9</td>
		</tr>
		<tr>
			<td>Microfil syringe needles</td>
			<td>World Precision Instruments</td>
			<td>MF28G67-5</td>
			<td>28 Gauge, 67 mm Long, (Pack of 5)</td>
		</tr>
		<tr>
			<td>Electrode holder</td>
			<td>Warner Instruments</td>
			<td>64-1280</td>
			<td>MP Series: Non-Electrical Pressure Applications</td>
		</tr>
		<tr>
			<td>Stimulating microelectrode</td>
			<td>FHC</td>
			<td>PBSA1075</td>
			<td>PBSA1075</td>
		</tr>
		<tr>
			<td>Air tank/regulator</td>
			<td>NU Laboratory Services</td>
			<td></td>
			<td>Air dry 300 CF</td>
		</tr>
		<tr>
			<td>Fast green</td>
			<td>Sigma Aldrich</td>
			<td>F7258-25G</td>
			<td>F7258-25G</td>
		</tr>
		<tr>
			<td>Clear plastic tape</td>
			<td>Scotch</td>
			<td>191</td>
			<td></td>
		</tr>
		<tr>
			<td>Doxycycline hyclate</td>
			<td>Sigma Aldrich</td>
			<td>D9891-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Egg refrigerator</td>
			<td>Vissani Wine Refrigerator</td>
			<td></td>
			<td>13.3-16.1&#176; C (56-61&#176; F)</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Hova-Bator</td>
			<td></td>
			<td>37.8&#176; C (100&#176; F), ~50% humidity</td>
		</tr>
		<tr>
			<td>Dissection scope</td>
			<td>Zeiss</td>
			<td>4.35E+15</td>
			<td>SteREO Discovery, V8 Microscope, 50.4X</td>
		</tr>
		<tr>
			<td>Cold-light source</td>
			<td>Zeiss</td>
			<td>4.36E+15</td>
			<td>CL6000 LED</td>
		</tr>
		<tr>
			<td>Micromanipulators</td>
			<td>Narishige Japan</td>
			<td>Model: MM-3</td>
			<td>2 Micromanipulators</td>
		</tr>
		<tr>
			<td>Capillary tubes</td>
			<td>Sutter Instrument</td>
			<td>BF150-86-10</td>
			<td>Thick-walled borosilicate (dimensions)</td>
		</tr>
		<tr>
			<td>Syringes</td>
			<td></td>
			<td></td>
			<td>1 mL, 3 mL</td>
		</tr>
		<tr>
			<td>Needles</td>
			<td>BD Precision Glide&#160;</td>
			<td></td>
			<td>27 G x 1 1/4, 19 G x 1 1/2</td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Stoelting</td>
			<td></td>
			<td>No. 5 Super Fine Dumont</td>
		</tr>
		<tr>
			<td>Egg holder</td>
			<td>Custom Made</td>
			<td></td>
			<td>Clay base works as well</td>
		</tr>
		<tr>
			<td>Micropipette puller</td>
			<td>Sutter Instrument</td>
			<td></td>
			<td>Model P-97</td>
		</tr>
		<tr>
			<td>Syringe filter</td>
			<td>Ultra Cruz</td>
			<td>sc-358811</td>
			<td>PVDF 0.22 &#956;m</td>
		</tr>
	</tbody>
</table>

in ovo electroporation in the chicken auditory brainstem

Electroporation is a method that introduces genes of interest into biologically relevant organisms like the chicken embryo. It is long established that the chicken embryo is an effective research model for studying basic biological functions of auditory system development. More recently, the chicken embryo has become particularly valuable in studying gene expression, regulation and function associated with hearing. In ovo electroporation can be used to target auditory brainstem regions responsible for highly specialized auditory functions. These regions include the chicken nucleus magnocellularis (NM) and nucleus laminaris (NL). NM and NL neurons arise from distinct precursors of rhombomeres 5 and 6 (R5/R6). Here, we present in ovo electroporation of plasmid-encoded genes to study gene-related properties in these regions. We show a method for spatial and temporal control of gene expression that promote either gain or loss of functional phenotypes. By targeting auditory neural progenitor regions associated with R5/R6, we show plasmid transfection in NM and NL. Temporal regulation of gene expression can be achieved by adopting a tet-on vector system. This is a drug inducible procedure that expresses the genes of interest in the presence of doxycycline (Dox). The in ovo electroporation technique &#8211; together with either biochemical, pharmacological, and or in vivo functional assays &#8211; provides an innovative approach to study auditory neuron development and associated pathophysiological phenomena.

We show here that in ovo electroporation permits gene expression in a normally developing biological system. Plasmid-encoded genes are focally injected into the neural tube overlying R5/R6. A schematic example of the electrode and pipette placements relative to important anatomical markers is shown in Figure 1A. The correct location of plasmid injection is confirmed 24 h after electroporation and shown in Figure 1B. The targeted injection of plas...

Watch this Scientific Journal Video about In Ovo Electroporation in the Chicken Auditory Brainstem at JoVE.com

In Ovo Electroporation in the Chicken Auditory Brainstem

Auditory brainstem neurons of avians and mammals are specialized for fast neural encoding, a fundamental process for normal hearing functions. These neurons arise from distinct precursors of embryonic hindbrain. We present techniques utilizing electroporation to express genes in the hindbrain of chicken embryos to study gene function during auditory development.

In Ovo Electroporation in the Chicken Auditory Brainstem

Electroporation is a method that introduces genes of interest into biologically relevant organisms like the chicken embryo. It is long established that ...

The overall goal of this procedure is to spatially and temporally control gene expression in the chicken auditory brainstem. The utilization of in ovo electroporation provides an innovative approach to study auditory neuron development and associated pathophysiological phenomena. This procedure can help you answer key questions in the field of auditory neural development, such as how does the control of gene expression promote either a gain or loss of phenotype that are required for normal auditory brainstem development.Demonstrating the procedure will be Doctor Ting Lu, a postdoctoral fellow from my laboratory. To begin, prepare plasmid solutions by adding one microliter of Fast Green solution for every seven microliters of DNA mixture. Next, mix DNA solutions at a one-to-one ratio for simultaneous electroporation of multiple plasmids.Once the plasmid solution is prepared, fabricate pipettes with a micropipette puller. Then use a 28-gauge syringe needle to fill the pipette with one to two microliters of the plasmid solution. Using forceps, break the pipette tip to 10 to 20 microns and determine the size of the broken tip under a microscope, then connect the pipette to a picospritzer via pipette holder.Prior to the procedure, store eggs purchased from a local vendor for no longer than five days in a refrigerator at 13 degrees Celsius. To begin, disinfect the egg with 70%ethanol, then to achieve proper embryo positioning, incubate the egg on its side at 38 degrees Celsius, and approximately 50%humidity to ensure optimal viability. After 48 to 52 hours of incubation, when the egg reaches Hamburger-Hamilton stage approximately 12 to 13, disinfect the work area and all instruments with 70%ethanol.Then remove the egg from the incubator, leave it at room temperature, and wipe it with 70%ethanol a second time. Using a light illuminator, identify the positioning of the embryo, visible as a dark area, and with a pencil, mark it by drawing a circle around its center. Poke a hold in the blunt end of the egg with a 19-gauge needle, then make a second hole near the drawn circle on the pointy end of the egg.Use the 19-gauge needle to remove a small piece of the outer eggshell, and with forceps, remove a small piece of the inner eggshell membrane. Next, introduce a 19-gauge needle attached to a three milliliter syringe through the hole at the blunt end of the egg, and withdraw 1.5 to 2.5 milliliters of albumin. Cover the hole at the blunt end of the egg with a one centimeter by one centimeter piece of tape, and then cover the drawn circle and the second hole with a 2.5 centimeter by four centimeter piece of tape.Using curved scissors with a cutting edge of 2.5 centimeters, and keeping them parallel to the eggshell, excise a window within the marked circle. To inject the plasmid, turn on the picospritzer and adjust the instrument's setting to apply pressure of 18 PSI for five microseconds, then turn on an air tank, and the lamp for the dissection microscope. Next, prepare 30 milliliters of a stock solution of the commercially purchased India Ink in sterile PBS.Aspirate the India Ink solution into a one milliliter syringe, then attach a 27-gauge needle and remove any bubbles that appear in the syringe. To visualize the embryo, introduce the needle just under the yolk membrane, approximately two to three millimeters from the embryo, and inject approximately 0.2 milliliters of India Ink. Then transfer the windowed egg to an egg holder, positioned under the dissection microscope, and switch to the highest magnification to achieve the best view of the plasmid injection site.Remove the membrane covering the injection area with forceps. Find the otocysts, and use them as landmarks to identify rhombomeres five and six, located nearby, from which nucleus magnocellularis and nucleus laminaris arise. Using a micromanipulator, position the pipette containing DNA in the neural tube that overlies the R5-R6 region in-between the otocysts.Eject DNA into the neural tube with the picospritzer. To begin electroporation, turn on the voltage stimulator, then attach a 0.22 micron syringe filter to a three milliliter syringe pre-filled with PBS, and add one to two drops of the filtered PBS onto the embryo. Subsequently, move a bipolar electrode toward the embryo using the micromanipulator, and position the negative electrode above the injection site, while maintaining the positive electrode lateral to the R5-R6.With the voltage stimulator, apply 20 pulses of 50 volts for one millisecond at one second intervals. You will see bubbles near the tip of the electrode. After electroporation, add one drop of PBS onto the exposed area, gently remove the electrode and clean it with a laboratory tissue and 70%ethanol, then cover the window over the embryo with tape.Finally, note the injected plasmid type, and the hatch date on the eggshell, and place the egg in the incubator with window-side facing up. Incubate the eggs at 38 degrees Celsius with 50%humidity, until desired developmental stage is reached. 24 hours after the electroporation, remove the egg from the incubator, open the window, and using a stereo microscope, confirm the correct location of the targeted plasmid injection.If tet-on vectors were used, pipette 50 microliters of Doxycycline into the chorioallantoic membrane, close the window, and put the egg back into the incubator. Presented here are photographs of a brainstem slice prepared from an embryonic day-12 chicken, taken under differential interference contrast illumination and fluorescent illumination. The nucleus magnocellularis and nucleus laminaris can be recognized within the brainstem slice.Under fluorescent illumination, both structures reveal the expression of yellow fluorescent protein, confirming efficient spatial expression of the electroporated genes. The expression of the electroporated gene can be also observed in a brainstem slice comprising the nucleus magnocellularis obtained from an embryonic day-18 chicken. When magnified 80 times, the classic adendritic cell bodies are visible under differential interference contrast illumination.Adendritic cell bodies reveal yellow fluorescent protein expression, further demonstrating that in ovo electroporation can induce gene expression in specific auditory brainstem regions for studies on auditory neuron development. Once mastered, and if it is performed properly, this technique can be done in two to three hours for approximately 12 viable eggs. Following this procedure, other methods like biochemical, pharmacological, and in vitro-in vivo functional assays can be performed in order to answer additional questions about how gene expression phenotypes regulate normal auditory brainstem development.After watching this video, you should have a good understanding of how to spatially and temporally control gene expression in the chicken auditory brainstem. In ovo electroporation permits genetic control of anatomical and physiological specializations, and well-defined time periods in auditory brainstem development.

in-ovo-electroporation-in-the-chicken-auditory-brainstem

Research

JoVE Journal

Developmental Biology

Efficient Gene Transfer in Chick Retinas for Primary Cell Culture Studies: An Ex-ovo Electroporation Approach

The cone photoreceptor-enriched cultures derived from embryonic chick retinas have become an indispensable tool for researchers around the world studying the biology of retinal neurons, particularly photoreceptors. The applications of this system go beyond basic research, as they can easily be adapted to high throughput technologies for drug development. However, genetic manipulation of retinal photoreceptors in these cultures has proven to be very challenging, posing an important limitation to the usefulness of the system. We have recently developed and validated an ex&#160;ovo plasmid electroporation technique that increases the rate of transfection of retinal cells in these cultures by five-fold compared to other currently available protocols1. In this method embryonic chick eyes are enucleated at stage 27, the RPE is removed, and the retinal cup is placed in a plasmid-containing solution and electroporated using easily constructed custom-made electrodes. The retinas are then dissociated and cultured using standard procedures. This technique can be applied to overexpression studies as well as to the downregulation of gene expression, for example via the use of plasmid-driven RNAi technology, commonly achieving transgene expression in 25% of the photoreceptor population. The video format of the present publication will make this technology easily accessible to researchers in the field, enabling the study of gene function in primary retinal cultures. We have also included detailed explanations of the critical steps of this procedure for a successful outcome and reproducibility.

Efficient Gene Transfer in Chick Retinas for Primary Cell Culture Studies: An Ex-ovo Electroporation Approach

Embryonic chick retinal cell cultures constitute valuable tools for the study of photoreceptor biology. We have developed an efficient gene transfer technique based on ex&#160;ovo plasmid electroporation of the retinas prior to culture. This technique considerably increases transfection efficiencies over currently available protocols, making genetic manipulation feasible for this system.

The cone photoreceptor-enriched cultures derived from embryonic chick retinas have become an indispensable tool for researchers around the world studying ...

Analysis of Zebrafish Larvae Skeletal Muscle Integrity with Evans Blue Dye

The zebrafish model is an emerging system for the study of neuromuscular disorders. In the study of neuromuscular diseases, the integrity of the muscle membrane is a critical disease determinant. To date, numerous neuromuscular conditions display degenerating muscle fibers with abnormal membrane integrity; this is most commonly observed in muscular dystrophies. Evans Blue Dye (EBD) is a vital, cell permeable dye that is rapidly taken into degenerating, damaged, or apoptotic cells; in contrast, it is not taken up by cells with an intact membrane. EBD injection is commonly employed to ascertain muscle integrity in mouse models of neuromuscular diseases. However, such EBD experiments require muscle dissection and/or sectioning prior to analysis. In contrast, EBD uptake in zebrafish is visualized in live, intact preparations. Here, we demonstrate a simple and straightforward methodology for performing EBD injections and analysis in live zebrafish. In addition, we demonstrate a co-injection strategy to increase efficacy of EBD analysis. Overall, this video article provides an outline to perform EBD injection and characterization in zebrafish models of neuromuscular disease.

In this study, we describe a straightforward method to perform Evans Blue Dye (EBD) analysis on zebrafish larvae. This technique is a powerful tool for the characterization of skeletal muscle integrity and delineation of zebrafish models of muscular dystrophy, and is a valuable method for the development of novel therapeutics.

The zebrafish model is an emerging system for the study of neuromuscular disorders.  In the study of neuromuscular diseases, the integrity of the muscle ...

Whole Retinal Explants from Chicken Embryos for Electroporation and Chemical Reagent Treatments

The retina is a good model for the developing central nervous system. The large size of the eye and most importantly the accessibility for experimental manipulations in ovo/in vivo makes the chicken embryonic retina a versatile and very efficient experimental model. Although the chicken retina is easy to target in ovo by intraocular injections or electroporation, the effective and exact concentration of the reagents within the retina may be difficult to fully control. This may be due to variations of the exact injection site, leakage from the eye or uneven diffusion of the substances. Furthermore, the frequency of malformations and mortality after invasive manipulations such as electroporation is rather high.
This protocol describes an ex ovo technique for culturing whole retinal explants from chicken embryos and provides a method for controlled exposure of the retina to reagents. The protocol describes how to dissect, experimentally manipulate, and culture whole retinal explants from chicken embryos. The explants can be cultured for approximately 24 hr and be subjected to different manipulations such as electroporation. The major advantages are that the experiment is not dependent on the survival of the embryo and that the concentration of the introduced reagent can be varied and controlled in order to determine and optimize the effective concentration. Furthermore, the technique is rapid, cheap and together with its high experimental success rate, it ensures reproducible results. It should be emphasized that it serves as an excellent complement to experiments performed in ovo.

This protocol describes a method to dissect, experimentally manipulate and culture whole retinal explants from chicken embryos. The explant cultures are useful when high success rate, efficacy and reproducibility are needed to test the effects of plasmids for electroporation and/or reagent substances, i.e., enzymatic inhibitors.

The retina is a good model for the developing central nervous system. The large size of the eye and most importantly the accessibility for experimental ...

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. The inner ear auditory sensory organ is critical for our ability to hear. It houses a highly specialized sensory epithelium that consists of mechano-transducing hair cells (HCs) and surrounding glial-like supporting cells (SCs). Despite structural differences in the auditory organs, molecular mechanisms regulating the development of the auditory organ are evolutionarily conserved between mammals and aves. In ovo electroporation is largely limited to early stages at E1 - E3. Due to the relative late development of the auditory organ at E5, manipulations of the auditory organ by in ovo electroporation past E3 are difficult due to the advanced development of the chicken embryo at later stages. The method presented here is a transient gene transfer method for targeting genes of interest at stage E4 - E4.5 in the developing chicken auditory sensory organ via in ovo micro-electroporation. This method is applicable for gain- and loss-of-functions with conventional plasmid DNA-based expression vectors and can be combined with in ovo cell proliferation assay by adding EdU (5-ethynyl-2&#180;-deoxyuridine) to the whole embryo at the time of electroporation. The use of green or red fluorescent protein (GFP or RFP) expression plasmids allows the experimenter to quickly determine whether the electroporation successfully targeted the auditory portion of the developing inner ear. In this method paper, representative examples of GFP electroporated specimens are illustrated; embryos were harvested 18 - 96 hr&#160;after electroporation and targeting of GFP to the pro-sensory area of the auditory organ was confirmed by RNA in situ hybridization. The method paper also provides an optimized protocol for the use of the thymidine analog EdU to analyze cell proliferation; an example of an EdU based cell proliferation assay that combines immuno-labeling and click EdU chemistry is provided.

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

The auditory organ mediates hearing. Here we present a modified in ovo micro-electroporation method optimized for studying auditory progenitor cell proliferation and differentiation in the developing chicken auditory organ.

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. ...

A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and molecular level. To alter intracardiac hemodynamics, fertilized chicken eggs are incubated in a humidified chamber to obtain embryos of the desired stage (HH17). Once this developmental stage is achieved, the embryo is maintained ex ovo and hemodynamics in the embryonic heart are altered by partially constricting the outflow tract (OFT) with a surgical suture at the junction of the OFT and ventricle (OVJ). Control embryos are also cultured ex ovo but are not subjected to the surgical intervention. Banded and control embryos are then incubated in a humidified incubator for the desired period of time, after which 2D ultrasound is employed to analyze the change in blood flow velocity at the OVJ as a result of OFT banding. Once embryos are maintained ex ovo, it is important to ensure adequate hydration in the incubation chamber so as to prevent drying and eventually embryo death. Using this new banded model, it is now possible to perform analyses of changes in the expression of key players involved in valve development and to understand the role of hemodynamics on cellular responses in vivo, which could not be achieved previously.

A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

For the first time we present here a reproducible banding procedure to alter hemodynamics in the developing heart ex ovo. This is achieved by partially constricting the outflow tract (OFT).

The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and ...

Embryo Microinjection and Electroporation in the Chordate Ciona intestinalis

Simple model organisms are instrumental for in vivo studies of developmental and cellular differentiation processes. Currently, the evolutionary distance to man of conventional invertebrate model systems and the complexity of genomes in vertebrates are critical challenges to modeling human normal and pathological conditions. The chordate Ciona intestinalis is an invertebrate chordate that emerged from a common ancestor with the vertebrates and may represent features at the interface between invertebrates and vertebrates. A common body plan with much simpler cellular and genomic composition should unveil gene regulatory network (GRN) links and functional genomics readouts explaining phenomena in the vertebrate condition. The compact genome of Ciona, a fixed embryonic lineage with few divisions and large cells, combined with versatile community tools foster efficient gene functional analyses in this organism. Here, we present several crucial methods for this promising model organism, which belongs to the closest sister group to vertebrates. We present protocols for transient transgenesis by electroporation, along with microinjection-mediated gene knockdown, which together provide the means to study gene function and genomic regulatory elements. We extend our protocols to provide information on how community databases are utilized for in silico design of gene regulatory or gene functional experiments. An example study demonstrates how novel information can be gained on the interplay, and its quantification, of selected neural factors conserved between Ciona and man. Furthermore, we show examples of differential subcellular localization in embryonic cells, following DNA electroporation in Ciona zygotes. Finally, we discuss the potential of these protocols to be adapted for tissue specific gene interference with emerging gene editing methods. The in vivo approaches in Ciona overcome major shortcomings of classical model organisms in the quest of unraveling conserved mechanisms in the chordate developmental program, relevant to stem cell research, drug discovery, and subsequent clinical application.

Embryo Microinjection and Electroporation in the Chordate Ciona intestinalis

We present transient transgenesis and gene knockdown in Ciona intestinalis, a chordate sister group to vertebrates, using microinjection and electroporation techniques. Such methods facilitate functional genomics in this simple invertebrate that features rudimentary characteristics of vertebrates, including notochord and head sensory epithelia, and many orthologs of human disease associated genes.

Simple model organisms are instrumental for in vivo studies of developmental and cellular differentiation processes. Currently, the evolutionary distance ...

Dissection and Immunofluorescent Staining of Mushroom Body and Photoreceptor Neurons in Adult Drosophila melanogaster Brains

Nervous system development involves a sequential series of events that are coordinated by several signaling pathways and regulatory networks. Many of the proteins involved in these pathways are evolutionarily conserved between mammals and other eukaryotes, such as the fruit fly Drosophila melanogaster, suggesting that similar organizing principles exist during the development of these organisms. Importantly, Drosophila has been used extensively to identify cellular and molecular mechanisms regulating processes that are required in mammals including neurogenesis, differentiation, axonal guidance, and synaptogenesis. Flies have also been used successfully to model a variety of human neurodevelopmental diseases. Here we describe a protocol for the step-by-step microdissection, fixation, and immunofluorescent localization of proteins within the adult Drosophila brain. This protocol focuses on two example neuronal populations, mushroom body neurons and retinal photoreceptors, and includes optional steps to trace individual mushroom body neurons using Mosaic Analysis with a Repressible Cell Marker (MARCM) technique. Example data from both wild-type and mutant brains are shown along with a brief description of a scoring criteria for axonal guidance defects. While this protocol highlights two well-established antibodies for investigating the morphology of mushroom body and photoreceptor neurons, other Drosophila brain regions and the localization of proteins within other brain regions can also be investigated using this protocol.

Dissection and Immunofluorescent Staining of Mushroom Body and Photoreceptor Neurons in Adult Drosophila melanogaster Brains

This protocol describes the dissection and immunostaining of adult Drosophila melanogaster brain tissues. Specifically, this protocol highlights the use of Drosophila mushroom body and photoreceptor neurons as example neuronal subsets that can be accurately used to uncover general principles underlying many aspects of neuronal development.

Nervous system development involves a sequential series of events that are coordinated by several signaling pathways and regulatory networks. Many of the ...

Visualizing the Node and Notochordal Plate In Gastrulating Mouse Embryos Using Scanning Electron Microscopy and Whole Mount Immunofluorescence

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is the formation of the transient organizers, the node and notochordal plate, from cells that have passed through the primitive streak. The proper formation of these signaling centers is essential for the development of the body plan and techniques to visualize them are of high interest to mouse developmental biologists. The node and notochordal plate lie on the ventral surface of gastrulating mouse embryos around embryonic day (E) 7.5 of development. The node is a cup-shaped structure whose cells possess a single slender cilium each. The proper subcellular localization and rotation of the cilia in the node pit determines left-right asymmetry. The notochordal plate cells also possess single cilia albeit shorter than those of the node cells. The notochordal plate forms the notochord which acts as an important signaling organizer for somitogenesis and neural patterning. Because the cells of the node and notochordal plate are transiently present on the surface and possess cilia, they can be visualized using scanning electron microscopy (SEM). Among other techniques used to visualize these structures at the cellular level is whole mount immunofluorescence (WMIF) using the antibodies against the proteins that are highly expressed in the node and notochordal plate. In this report, we describe our optimized protocols to perform SEM and WMIF of the node and notochordal plate in developing mouse embryos to help in the assessment of tissue shape and cellular organization in wild-type and gastrulation mutant embryos.

The node and notochordal plate are transient signaling organizers in developing mouse embryos that can be visualized using several techniques. Here, we describe in detail how to perform two of the techniques to study their structure and morphogenesis: 1) scanning electron microscopy (SEM); and 2) whole mount immunofluorescence (WMIF).

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is ...

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.

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 ...

Electroporation-mediated RNA Interference Method in Odonata

Dragonflies and damselflies (order Odonata) represent one of the most ancestral insects with metamorphosis, in which they change their habitat, morphology, and behavior drastically from aquatic larvae to terrestrial/aerial adults without pupal stage. Odonata adults have a well-developed color vision and show a remarkable diversity in body colors and patterns across sexes, stages, and species. While many ecological and behavioral studies on Odonata have been conducted, molecular genetic studies have been scarce mainly due to the difficulty in applying gene functional analysis to Odonata. For instance, RNA interference (RNAi) is less effective in the Odonata, as reported in the Lepidoptera. To overcome this problem, we successfully established an RNAi method combined with in vivo electroporation. Here we provide a detailed protocol including a video of the electroporation-mediated RNAi method as follows: preparation of larvae, species identification, preparation of dsRNA/siRNA solution and injection needles, ice-cold anesthesia of larvae, dsRNA/siRNA injection, in vivo electroporation, and individual rearing until adult emergence. The electroporation-mediated RNAi method is applicable to both damselflies (suborder Zygoptera) and dragonflies (suborder Anisoptera). In this protocol, we present the methods for the blue-tailed damselfly Ischnura senegalensis (Coenagrionidae) as an example of damselfly species and the pied skimmer dragonfly Pseudothemis zonata (Libellulidae) as another example of dragonfly species. As representative examples, we show the results of RNAi targeting the melanin synthesis gene multicopper oxidase 2. This RNAi method will facilitate understanding of various gene functions involved in metamorphosis, morphogenesis, color pattern formation, and other biological features of Odonata. Moreover, this protocol may be generally applicable to non-model organisms in which RNAi is less effective in gene suppression due to the inefficiency and low penetrance.

We provide a detailed protocol for electroporation-mediated RNA interference in insects of the order Odonata (dragonflies and damselflies) using the blue-tailed damselfly (Ischnura senegalensis: Coenagironidae: Zygoptera) and the pied skimmer dragonfly (Pseudothemis zonata: Libellulidae: Anisoptera).