Name: reverse genetic morpholino approach using cardiac ventricular injection to transfect multiple difficult-to-target tissues in the zebrafish larva
Uploaded: 2014-06-17T15:00:00
Description: Watch this Scientific Journal Video about Reverse Genetic Morpholino Approach Using Cardiac Ventricular Injection to Transfect Multiple Difficult-to-target Tissues in the Zebrafish Larva at JoVE.com

This work was supported by the Deutsche Forschungsgemeinschaft (DFG), we wish to thank Ayele Tsedeke Taddese for technical support.

1. Preparation of the Glass Needles (Figure 1)
<ol>
	<li>Use glass capillaries with a 0.75 mm diameter to prepare injection needles (Figure 1A).</li>
	<li>Place the glass capillary into a needle puller and pull the needle with the following parameter: heating cycle value: 463; pulling cycle value: 230; velocity: 150 msec; time: 150 msec (Figure 1B).</li>
	<li>Break the pulled glass capillary with watchmaker tweezers to produce a 20 &#181;m diameter needle under a stereoscope with a mic...

<ol>
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The intraventricular injection provides a quick and reliable assessment method for testing gene function at later stages of development or of body homeostasis without affecting the gene function during embryogenesis. To ensure the success of this technique, one should be aware of four critical points: 1) needle size, 2) drying out of the needle, 3) minimizing volume, and 4) minimal exposure time in the sedation solution. Needles that are too small&#160;will clog frequently, while needles that are too large will damage th...

Regeneration of organs and appendages is fundamentally important for survival and fitness; however, several vertebrates including man have limited regenerative abilities. While several animal models exist that have extensive regenerative capacity, reverse genetic techniques to assess gene function during organ and appendage regeneration remain very limited or non-existent. Therefore, new approaches are required to dissect the molecular biology of regeneration in these model organisms.
The zebrafish is a well-established model for understanding the cell and molecular biology of organ and appendage regeneration1, not only because of its significant ability to regenerate multiple organs, tissues and appendages, but also because several transgenic fish lines exist to track cells and to overexpress gene constructs2,3. However, gene inhibition in larval zebrafish is mainly limited to the overexpression of dominant-negative constructs, which are not available to all genes of interest or whose transgene product can acquire gain-of-function effects that do not reflect the endogenous activity of the gene. Thus, an alternative method to specifically remove gene expression by knockout or knockdown is needed to overcome these issues.
Gene-specific targeting using TALENS exists as a reverse genetic means to knockout gene function; however, this knockout strategy is very frequently limited to functional assessments during early embryogenesis, because initial requirements of the gene prevent further progression of embryonic development. Thus, studying later phenomena such as regeneration or organ homeostasis after development using TALENS is precluded4,5. Therefore, an alternate gene removal strategy is needed that targets gene function after early development to assess gene requirements in fully formed organs and structures.
Morpholino injection has been shown to be effective in targeting genes in a few adult organs and the adult regenerating fin6-8, but these methods require electroporation and many internal organs are difficult to electroporate either due to their location or due to their sensitivity to electrical disruption. Furthermore, some tissues in the larva are difficult to inject directly, because direct injection may disrupt their structural integrity or because their size is limiting. The caudal fin of the larva is one such structure, because direct injection into the finfold is not possible. Thus, an alternative to electroporation and direct injection was needed to target genes in tissues that are either too small to inject or can&#39;t be electroporated.
In order to target and inhibit the function of specific genes during the regeneration of the larval caudal fin, we have modified existing morpholino technologies allowing the assessment of gene function during caudal fin regeneration in late-staged larva. This method employs intraventricular delivery9 of fluorescein-tagged morpholinos together with Endo-Porter transfection reagent10. Once in the ventricle, the morpholino-Endo-Porter mixture quickly spreads throughout the larva via the vasculature and enters tissues that have been previously impossible to target. This injection method may be modified to target genes in specific tissues and quite possibly can be applied in other animal models that currently lack reverse genetic methods to inhibit gene function. Thus, it offers a quick and easy method with the potential for broad range use to immediately study gene function during general organ homeostasis and regeneration at larval stages.

<table border="0" cellpadding="0" cellspacing="0" style="width:672px;" width="673">
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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:171px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Reagent/Material</td>
			<td style="width:171px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Morpholino with 3&#180;fluorescein tag</td>
			<td style="width:171px;">Gene Tools Inc.&#160;</td>
			<td style="width:119px;">Customized</td>
			<td style="width:167px;">More information on www.genetools.com</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Endo-Porter</td>
			<td style="width:171px;">Gene Tools Inc.&#160;</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">More information on www.genetools.com</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Agarose</td>
			<td style="width:171px;">Serva</td>
			<td style="width:119px;">120623</td>
			<td style="width:167px;">For pouring plates to place the fish during injections and imaging</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Tricane (L-Ethyl-m-amino-benzate-methane sulfonate)</td>
			<td style="width:171px;">Applichem</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">For anesthesia</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">E3 medium (5 mM NaCl; 0.17 mM KCl; 0.33 mM CaCl2; 0.33 mM MgSo4)</td>
			<td style="width:171px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">For larval husbandry</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Petri Dishes</td>
			<td style="width:171px;">Sarstedt</td>
			<td style="width:119px;">821.472</td>
			<td style="width:167px;">For placing the fish during injections and imaging</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">&#160;Equipment</td>
			<td style="width:171px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Thin Wall Glass Capillaries</td>
			<td style="width:171px;">World Precision Instruments, Inc.&#160;</td>
			<td style="width:119px;">TW100F-3</td>
			<td style="width:167px;">For preparing injection needles</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Microloader pipette tips</td>
			<td style="width:171px;">Eppendorf</td>
			<td style="width:119px;">5,242,956,003</td>
			<td style="width:167px;">For loading the needle</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Pasteur Pipettes (3 ml/1 ml)</td>
			<td style="width:171px;">Brand</td>
			<td style="width:119px;">747760/ 74775</td>
			<td style="width:167px;">For transfering larva</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Flaming / Brown&#160; needle puller&#160;</td>
			<td style="width:171px;">Sutter</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">More information on www.sutter.com</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Watchmaker (Dumont) Tweezers (size 5)</td>
			<td style="width:171px;">World Precision Instruments, Inc.&#160;</td>
			<td style="width:119px;">501985</td>
			<td style="width:167px;">To brake the needle before sharpening</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dissecting microscope</td>
			<td style="width:171px;">Olympus, Leica, Zeiss</td>
			<td style="width:119px;">Varies with the manufacturer</td>
			<td style="width:167px;">Part of the whole injection setup</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Fluorescence camera</td>
			<td style="width:171px;">Olympus, Leica, Zeiss</td>
			<td style="width:119px;">Varies with the manufacturer</td>
			<td style="width:167px;">To image the fluorescence after injeciton</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">PicoNozzle kit (microinjector holder)</td>
			<td style="width:171px;">World Precision Instruments</td>
			<td style="width:119px;">5430-12</td>
			<td style="width:167px;">For microinjections</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Pneumatic PicoPump (microinjector)</td>
			<td style="width:171px;">World Precision Instruments</td>
			<td style="width:119px;">SYS-PV820</td>
			<td style="width:167px;">For microinjections</td>
		</tr>
	</tbody>
</table>

reverse genetic morpholino approach using cardiac ventricular injection to transfect multiple difficult-to-target tissues in the zebrafish larva

The zebrafish is an important model to understand the cell and molecular biology of organ and appendage regeneration. However, molecular strategies to employ reverse genetics have not yet been adequately developed to assess gene function in regeneration or tissue homeostasis during larval stages after zebrafish embryogenesis, and several tissues within the zebrafish larva are difficult to target. Intraventricular injections of gene-specific morpholinos offer an alternative method for the current inability to genomically target zebrafish genes in a temporally controlled manner at these stages. This method allows for complete dispersion and subsequent incorporation of the morpholino into various tissues throughout the body, including structures that were formerly impossible to reach such as those in the larval caudal fin, a structure often used to noninvasively research tissue regeneration. Several genes activated during larval finfold regeneration are also present in regenerating adult vertebrate tissues, so the larva is a useful model to understand regeneration in adults. This morpholino dispersion method allows for the quick and easy identification of genes required for the regeneration of larval tissues as well as other physiological phenomena regulating tissue homeostasis after embryogenesis. Therefore, this delivery method provides a currently needed strategy for temporal control to the evaluation of gene function after embryogenesis.&#160;

The sharp, beveled injection needle is easily placed in the cardiac ventricle of the zebrafish larva when approached dorsally (Figure 3A). The heart continues pumping and blood flow is maintained despite the presence of the needle (Figures 3B and 3C). Careful injections do not disrupt the morphology of the ventricle or cardiac contractions (Figure 3D) despite injection of the morpholino into the heart (Figure 3E).
<p class="jove_cont...

Watch this Scientific Journal Video about Reverse Genetic Morpholino Approach Using Cardiac Ventricular Injection to Transfect Multiple Difficult-to-target Tissues in the Zebrafish Larva at JoVE.com

Reverse Genetic Morpholino Approach Using Cardiac Ventricular Injection to Transfect Multiple Difficult-to-target Tissues in the Zebrafish Larva (Video) | JoVE

An adaptable reverse genetic method for zebrafish to assess gene function during later stages of development and physiological homeostasis such as tissue regeneration using intraventricular injections of gene-specific morpholinos.

Reverse Genetic Morpholino Approach Using Cardiac Ventricular Injection to Transfect Multiple Difficult-to-target Tissues in the Zebrafish Larva

The zebrafish is an important model to understand the cell and molecular biology of organ and appendage regeneration. However, molecular strategies to ...

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