Name: laser-assisted cytoplasmic microinjection in livestock zygotes
Uploaded: 2016-10-05T14:00:00
Description: Watch this Scientific Journal Video about Laser-assisted Cytoplasmic Microinjection in Livestock Zygotes at JoVE.com

Work related to this technique is supported by NIH/NICHD RO1 HD070044 and USDA/NIFA Hatch projects W-3171 and W-2112.

1. Micropipette Production
<ol>
	<li>Injection micropipette
	<ol>
		<li>Place a borosilicate glass capillary (outer diameter (OD): 1.0 mm, inner diameter (ID): 0.75 mm) in a micropipette puller (in the center of the right and left capillary holders) and lock it.</li>
		<li>Use an appropriate program to pull the glass capillary so it results in a thin tip with a long tapper. (Example: Heat: 825; Pull: 30; Velocity: 120; Time: 200; Pressure: 500).</li>
		<li>Carefully remove the pulled pipettes from the device and place ...

<ol>
	<li>McEvoy, T., Coull, G., Broadbent, P., Hutchinson, J., Speake, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fatty+acid+composition+of+lipids+in+immature+cattle,+pig+and+sheep+oocytes+with+intact+zona+pellucida.">Fatty acid composition of lipids in immature cattle, pig and sheep oocytes with intact zona pellucida.</a> J Reprod Fertil. 118 (1), 163-170 (2000).</li><li>Brinster, R. L., Chen, H. Y., Trumbauer, M. E., Yagle, M. K., Palmiter, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+affecting+the+efficiency+of+introducing+foreign+DNA+into+mice+by+microinjecting+eggs.">Factors affecting the efficiency of introducing foreign DNA into mice by microinjecting eggs.</a> Proc Natl Acad Sci U S A. 82 (13), 4438-4442 (1985).</li><li>Ross, P. 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=Parthenogenetic+activation+of+bovine+oocytes+using+bovine+and+murine+phospholipase+C+zeta.">Parthenogenetic activation of bovine oocytes using bovine and murine phospholipase C zeta.</a> BMC Dev Biol. 8 (1), (2008).</li><li>Canovas, J., Cibelli, J. B., Ross, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Jumonji+domain-containing+protein+3+regulates+histone+3+lysine+27+methylation+during+bovine+preimplantation+development.">Jumonji domain-containing protein 3 regulates histone 3 lysine 27 methylation during bovine preimplantation development.</a> Proc Natl Acad Sci U S A. 109 (7), 2400-2405 (2012).</li><li>Bogliotti, Y. 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=4+Developmental+outcomes+and+effiency+of+two+CRISPR/Cas9+microinjection+methods+in+bovine+zygotes.">4 Developmental outcomes and effiency of two CRISPR/Cas9 microinjection methods in bovine zygotes.</a> Reprod Fertil Dev. 27 (1), 94-94 (2015).</li><li>Bakhtari, A., Ross, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DPPA3+prevents+cytosine+hydroxymethylation+of+the+maternal+pronucleus+and+is+required+for+normal+development+in+bovine+embryos.">DPPA3 prevents cytosine hydroxymethylation of the maternal pronucleus and is required for normal development in bovine embryos.</a> Epigenetics. 9 (9), 1271-1279 (2014).</li><li>Yaul, M., Bhatti, R., Lawrence, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluating+the+process+of+polishing+borosilicate+glass+capillaries+used+for+fabrication+of+in-vitro+fertilization+(iVF)+micro-pipettes.">Evaluating the process of polishing borosilicate glass capillaries used for fabrication of in-vitro fertilization (iVF) micro-pipettes.</a> Biomed Microdevices. 10 (1), 123-128 (2008).</li><li>Sutter Instrument. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Pipette Cookbook 2015 P-97 &amp; P-1000 Micropipette Pullers. , (2015).</li><li>Sutter Instrument. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> P-97 Flaming/BrownTM Micropipette Puller Operation Manual Rev. 2.30 - DOM (20140825). , (2014).</li><li>Cibelli, J. B., Lanza, R. P., Campbell, K. H. S., West, M. 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> Principles of cloning. , (2002).</li><li>Wang, B., 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=Expression+of+a+reporter+gene+after+microinjection+of+mammalian+artificial+chromosomes+into+pronuclei+of+bovine+zygotes.">Expression of a reporter gene after microinjection of mammalian artificial chromosomes into pronuclei of bovine zygotes.</a> Mol Reprod Dev. 60 (4), 433-438 (2001).</li></ol>

Microinjection of zygotes is a well-established method for introducing solutions into mammalian embryos. With some variations dependent on the species and the aim of the experiment, this technique can be broadly used. We show how to perform intracytoplasmic microinjection using a laser to assist the entrance of a blunt-end micropipette. Zygotes of some livestock species (such as cattle, sheep, and pig) have a dark cytoplasm, hindering the visualization of the injection pipette once inside the embryo. Also, their plasma m...

Cytoplasmic microinjection of 1-cell embryos is a very powerful technique. It can be used for delivering any solution into the embryo to, for example, produce gene knock-outs to study gene function or to generate gene-edited animals. Most agriculturally-relevant farm animal zygotes have a very high fatty acid composition that makes their cytoplasm opaque and dark1. They also have a fairly elastic plasma membrane (PM). These characteristics make microinjection using conventional pronuclear/cytoplasmic injection as used in rodent species challenging and often inaccurate.
Cytoplasmic microinjection has advantages over pronuclear microinjection since it is easier to perform and also causes less damage to the injected embryos, resulting in higher viability2. The overall goal of this protocol is to demonstrate a successful method for delivering solutions into the cytoplasm of farm animal zygotes. To be able to perform cytoplasmic microinjection with high efficiency on livestock embryos, a laser is used to generate a hole in the zona pellucida (ZP) and then a blunt-end glass needle is used for the microinjection. This strategy aims to reduce the mechanical damage imprinted on the embryo during injection. Then, aspiration of cytoplasmic content inside the injection needle allows efficient and confident breakage of the PM ensuring that the solution is delivered into the cytoplasm of the embryo.
This technique has already been successfully used in bovine embryos to deliver siRNA into the zygotic cytoplasm3,4 and to generate mutations using the clustered regularly interspaced short palindromic repeats (CRISPR) / CRISPR associated system 9 (Cas9) system5. It is also suitable (with minor modifications) to inject bovine cumulus-enclosed oocytes6. Here, we describe our injection protocol delivering a dye, that can be applicable to injecting any desired solution into the zygote, and show that using this technique causes minimal lysis and does not affect early embryo development.

<table border="0" cellpadding="0" cellspacing="0" width="786">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:268px;">Micropipette puller</td>
			<td style="width:143px;">Sutter Instrument</td>
			<td style="width:119px;">P-97</td>
			<td style="width:257px;"></td>
		</tr>
		<tr height="80">
			<td height="80" style="height:80px;width:268px;">Glass capillary</td>
			<td style="width:143px;">Sutter instruments</td>
			<td style="width:119px;">B100-75-10</td>
			<td style="width:257px;">These capillaries are used for making the holding and injecting pipettes. Any thick/standard wall borosilicate tubing without filament can be used.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:268px;">Microforge</td>
			<td style="width:143px;">Narishige</td>
			<td style="width:119px;">MF-9</td>
			<td>Equipped with 10X magnification lense.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:268px;">Micromanipulator</td>
			<td style="width:143px;">Nikon/ Narishige</td>
			<td>NT88-V3</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">Inverted microscope</td>
			<td style="width:143px;">Nikon</td>
			<td>TE2000-U</td>
			<td style="width:257px;">Equipped with 4x, 20x lenses and with a laser system.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Laser</td>
			<td style="width:143px;">Research Instruments</td>
			<td>7-47-500</td>
			<td>Saturn 5 Active laser.</td>
		</tr>
		<tr height="80">
			<td height="80" style="height:80px;width:268px;">Microdispenser</td>
			<td>Drummond</td>
			<td>3-000-105</td>
			<td style="width:257px;">The microdispenser is used to move the embryos. A p10 pipette can also be used but loading as minimal volume as possible.</td>
		</tr>
		<tr height="100">
			<td height="100" style="height:100px;width:268px;">60mm culture dish</td>
			<td style="width:143px;">Corning</td>
			<td style="width:119px;">430166</td>
			<td style="width:257px;">Use the lid of the dish to make the injection plate since they have lower walls and will make positioning and moving of the micropipettes with the micromanipulator easier.&#160;</td>
		</tr>
		<tr height="160">
			<td height="160" style="height:160px;width:268px;">35mm culture dish</td>
			<td style="width:143px;">Corning</td>
			<td style="width:119px;">430165</td>
			<td style="width:257px;">These dishes are used for culturing the embryos in 50&#956;l drops covered with mineral oil. Alternatively, a 4 well dish can also be used. Regardless of the dish chosen to culture the embryos, they always have to be equilibrated in the incubator for at least 4 hours prior to transfering the embryos to them.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">Incubator</td>
			<td style="width:143px;">Sanyo</td>
			<td style="width:119px;">MCO-19AIC</td>
			<td style="width:257px;">Any incubator that can be set to 38.5&#176;C 5% CO2 conditions can be used.</td>
		</tr>
		<tr height="80">
			<td height="80" style="height:80px;width:268px;">Stereomicroscope</td>
			<td style="width:143px;">Nikon</td>
			<td>SMZ800</td>
			<td style="width:257px;">Used for visualizing the embryos in the culture drops and during washes. Any stereomicroscope with a 10x magnification can be used.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Control Unit HT</td>
			<td style="width:143px;">Minitube</td>
			<td>12055/0400</td>
			<td style="width:257px;">Heating system attached to the stereomicroscope.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Heated Microscope Stage</td>
			<td style="width:143px;">Minitube</td>
			<td>12055/0003</td>
			<td style="width:257px;">Heating system attached to the stereomicroscope.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:268px;">Dextran-Red</td>
			<td>Thermo Scientific</td>
			<td>D1828</td>
			<td>A sterile 10mg/ml solution is used to inject.</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:268px;">Mineral Oil</td>
			<td style="width:143px;">sigma</td>
			<td style="width:119px;">M8410</td>
			<td style="width:257px;">Keep the mineral oil at room temperature and&#160; protected from light using foil paper.</td>
		</tr>
		<tr height="80">
			<td height="80" style="height:80px;width:268px;">KSOMaa Evolve Bovine</td>
			<td style="width:143px;">Zenit</td>
			<td style="width:119px;">ZEBV-100</td>
			<td style="width:257px;">Supplemented with 4mg/ml BSA. KSOM plates for embryo culture should be equilibrated in an incubator for at least 4 hours before use.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:268px;">FBS</td>
			<td style="width:143px;">Gemini-Bio</td>
			<td style="width:119px;">100-525</td>
			<td>Use a stem-cell qualified FBS.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">Zygotes</td>
			<td style="width:143px;"></td>
			<td style="width:119px;"></td>
			<td style="width:257px;">Zygotes are injected 17-20 hpf and can be in-vitro- or in-vivo-derived.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">NaCl</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">S5886</td>
			<td style="width:257px;">Final concentration: 107.7mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">KCl</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">P5405</td>
			<td style="width:257px;">Final concentration: 7.16mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">KH2PO4</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">P5655</td>
			<td style="width:257px;">Final concentration: 1.19mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">MgCL2 6H2O</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">M2393</td>
			<td style="width:257px;">Final concentration: 0.49mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">Sodium DL-lactate</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">L4263</td>
			<td style="width:257px;">Final concentration: 5.3mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">CaCl2-2H2O&#160;</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">C7902</td>
			<td style="width:257px;">Final concentration: 1.71mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">D-(&#8722;)-Fructose&#160;</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">F3510</td>
			<td style="width:257px;">Final concentration: 0.5mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">HEPES&#160;</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">H4034</td>
			<td style="width:257px;">Final concentration: 21mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">MEM-NEAA</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">M7145</td>
			<td style="width:257px;">Final concentration: 1X. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">BME-EAA</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">B6766</td>
			<td style="width:257px;">Final concentration: 1X. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">NaHCO3</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">S5761</td>
			<td style="width:257px;">Final concentration: 4mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">Sodium pyruvate</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">P4562</td>
			<td style="width:257px;">Final concentration: 0.33mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">Glutamax</td>
			<td style="width:143px;">Gibco</td>
			<td style="width:119px;">35050</td>
			<td style="width:257px;">Final concentration: 1mM. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">BSA</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">A-3311</td>
			<td style="width:257px;">Final concentration: 1mg/ml. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:268px;">Gentamicin</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">G-1397</td>
			<td style="width:257px;">Final concentration: 5&#956;g/ml. Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:268px;">Water for embryo transfer</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">W1503</td>
			<td style="width:257px;">Component of SOF-HEPES medium.</td>
		</tr>
		<tr height="80">
			<td height="80" style="height:80px;width:268px;">SOF-HEPES medium</td>
			<td style="width:143px;">Made in the lab</td>
			<td style="width:119px;"></td>
			<td style="width:257px;">pH 7.3-7.4, 280&#177;10 mOs. Filter sterilized through a 22&#956;m filter can be stored in the fridge at 4&#176; C for 1 month. Warm in 37 &#176;C water bath before use.</td>
		</tr>
	</tbody>
</table>

laser-assisted cytoplasmic microinjection in livestock zygotes

Cytoplasmic microinjection into one-cell embryos is a very powerful technique. As an example, it enables the delivery of genome editing tools that can create genetic modifications that will be present in every cell of an adult organism. It can also be used to deliver siRNA, mRNAs or blocking antibodies to study gene function in preimplantation embryos. The conventional technique for microinjecting embryos used in rodents consists of a very thin micropipette that directly penetrates the plasma membrane when advanced into the embryo. When this technique is applied to livestock animals it usually results in low efficiency. This is mainly because in contrast to mice and rats, bovine, ovine, and porcine zygotes have a very dark cytoplasm and a highly elastic plasma membrane that makes visualization during injection and penetration of the plasma membrane hard to achieve. In this protocol, we describe a suitable microinjection method for the delivery of solutions into the cytoplasm of cattle zygotes that has proved to be successful for sheep and pig embryos as well. First, a laser is used to create a hole in the zona pellucida. Then a blunt-end glass micropipette is introduced through the hole and advanced until the tip of the needle reaches about 3/4 into the embryo. Then, the plasma membrane is broken by aspiration of cytoplasmic content inside the needle. Finally, the aspirated cytoplasmic content followed by the solution of interest is injected back into the embryonic cytoplasm. This protocol has been successfully used for the delivery of different solutions into bovine and ovine zygotes with 100% efficiency, minimal lysis, and normal blastocysts development rates.

Laser-assisted cytoplasmic microinjection is a powerful and reliable protocol to deliver solutions into the cytoplasm of livestock zygotes. Figure 3 shows a general outline of the zygotes before and after injection as well as the overall outline of the technique. Dextran-red is used as injecting solution to allow tracking site of injection and injection efficiency and accuracy. Successful delivery of the solution is illustrated in Figure 4 showing a recen...

Watch this Scientific Journal Video about Laser-assisted Cytoplasmic Microinjection in Livestock Zygotes at JoVE.com

Laser-assisted Cytoplasmic Microinjection in Livestock Zygotes

This protocol shows how to perform cytoplasmic microinjection in farm animal zygotes. This technique can be used to deliver any solution into the one-cell embryo such as genome editing tools to generate knockout animals.

Cytoplasmic microinjection into one-cell embryos is a very powerful technique. As an example, it enables the delivery of genome editing tools that can ...

The overall goal of this procedure is to effectively deliver solutions into the cytoplasm of livestock zygotes using a blunt-end needle with the aid of a laser. This method is used in research and in the animal trans-genesis field, since one is associated with a genome-editing tool, such as a CRISPR Cas9 system, it can create new cows to study gene function and transgenic animals in a very simple and reliable way. The main advantage of this technique is that it can be used to deliver any solution into a cytoplasm of large animal's zygotes.With a handy person's injection efficiency minimalizes animal liver lomotil rates. First, prepare the injection micropipette by placing a borosilicate glass capillary into a micropipette puller and locking it into place. Use an appropriate program to pull the capillary so it results in a thin tip with a long taper.Then, carefully remove the pulled pipettes from the device and place them onto a microforge in a horizontal position. Bring the pulled pipette and the microforge heater filament, with it's glass bead, into focus. Use the eyepiece reticle to measure the desired thickness, and move the pipette horizontally until the heater filament reaches the target inner diameter of five micrometers.Adjust the heat to about 45%and gently bring the pipette down so it touches the filament. Then, briefly activate the heater. This will slightly melt the pipette so it adheres to the filament, and upon cooling, the pipette will break at the contact point, generating a straight cut.Setting the right temperature is key in this step. Temperatures too high will bend the pipette, while temperatures too low will not be sufficient for cutting the pipette. Next, make an approximate 30 degree angle near the pipette tip by positioning the tip about 10 micrometers away from the heater filament.Set the temperature to 60%and activate the heater so that the pipette bends over the filament to the desired angle. Using the settings shown here, pull a glass capillary that results in a micro-pipette having a thin tip with a long, even taper and parallel walls. Carefully remove the pulled pipette from the puller device and place it on the microforge holder in a horizontal position.Use the eyepiece reticle to measure the pipette diameter and move the pipette until its diameter over the filament reaches 180 micrometers. Mark the glass capillary with a diamond-tipped pen and then gently press on the pulled tip to break the glass. This should result in a straight cut.Next, move the pipette to a vertical position, with its tip close to the filament. Set the temperature of the microforge to 60%and fire-polish the tip of the pipette, using standard techniques until the inner diameter reaches the target size. Measure the inner diameter of the pipette, which should be 40 micrometers.Using the same procedure as before, bend the tip to a 30 degree angle. Insert the holding pipette into the left micro-manipulator holder and the injection pipette into the right micro-manipulation holder. Then, fill the injection pipette with oil.Use the micro-manipulator controls to bring the pipettes into the center of the microscope's field of view. Using 4X magnification, check that the micro-pipette tips are at the correct angle so that they are parallel to the bottom of the dish. Place a 50 microliter drop of 37 degree celsius SOF-HEPES solution, that is supplemented with 20%FBS onto the center of the lid of a 100 millimeter petri dish.Then, place a one to two microliter drop of the solution to be injected close to the injection drop. Next, cover the drops and the injection plate using approximately 10 milliliters of mineral oil. Place the plate on the microscope stage and use a microdispenser to load about 20 to 30 zygotes in the upper side of the injection drop.Using the 4X objective, load the solution to be injected into the injection pipette by applying negative pressure to the microinjector. Load a sufficient amount of solution to inject two to three zygotes and then move to the injection drop. Within the injection drop, move the holding pipette so the tip gets close to a zygote.Apply negative pressure with the holding micro-injector so the zygote gets fixed to the holding pipette. Once the zygote is secure, change to a 20X objective. Check that the injection pipette is positioned on the embryo's mid-plane by gently touching the zygote on the site of injection.If it is not on its mid-plane, the needle will tend to make the embryo rotate, instead of puncture. Next, use software to place the laser vertical in the zona pellucida where the hole will be made. Once correctly positioned, use the laser control window and click on the FIRE button.Ensure that the size of the hole is large enough to create an opening in the zona pellucida for the needle to pass through without damaging the plasma membrane. Pass the injection needle through the hole in the zona pellucida and make contact with the plasma membrane. Continue pushing the pipette forward until the needle is 3/4 of the way into the embryo.Observe the position of the meniscus at the solution oil interphase. This will be used to consistently control the injection volume. Apply negative pressure on the injection pipette to aspirate the plasma membrane and cytoplasm into the injection needle.Continue until the movement of cytoplasm in the needle accelerates or when cytoplasm content, mixing with the injection solution, can be seen. These will indicate breakage of the plasma membrane. Inject back the cytoplasmic content, followed by the solution into the cytoplasm of the zygote, by applying positive pressure until the meniscus at the solution oil interphase has advanced one zygote's diameter equivalent past the starting point.Then, change to a 4X objective, and move the injected embryo to the lower side of the injection drop. Release the embryo by applying positive pressure on the holding micro-injector. Collect the injected embryos using a micro-dispenser.Wash the injected embryos by moving them through the three drops of SOF-HEPES and culture them, as described in the accompanying text protocol. Successful delivery of the solution is visible in the fluorescent image, where dexion red is used to track the site of injection and injection efficiency and accuracy. Here, the dye is homogeneously distributed in the cytoplasm, which is typical when using this technique.This protocol has minimal lysis rates in bovine and ovine zygotes. Few of the injected embryos were lysed in cattle, or sheep as a result of microinjection. Also, there are no statistically significant differences in blastocyst development rates in the control versus injected groups for both bovine and ovine embryos.Once mastered, this technique can be done at the rate of two embryos per minute. With a handy person injection efficiency, minimalizes animal blastocyst rates. After watching this video, you should understand how to perform laser-assisted intracytoplasmic micro-injection in livestock zygotes.And also how to use positive and negative suction pressure to assure the rupture of the plasma membrane for an efficient delivery.

laser-assisted-cytoplasmic-microinjection-in-livestock-zygotes

Research

JoVE Journal

Genetics

Delivery of Nucleic Acids through Embryo Microinjection in the Worldwide Agricultural Pest Insect, Ceratitis capitata

The Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a pest species with extremely high agricultural relevance. This is due to its reproductive behavior: females damage the external surface of fruits and vegetables when they lay eggs and the hatched larvae feed on their pulp. Wild C. capitata populations are traditionally controlled through insecticide spraying and/or eco-friendly approaches, the most successful being the Sterile Insect Technique (SIT). The SIT relies on mass-rearing, radiation-based sterilization and field release of males that retain their capacity to mate but are not able to generate fertile progeny. The advent and the subsequent rapid development of biotechnological tools, together with the availability of the medfly genome sequence, has greatly boosted our understanding of the biology of this species. This favored the proliferation of new strategies for genome manipulation, which can be applied to population control.
In this context, embryo microinjection plays a dual role in expanding the toolbox for medfly control. The ability to interfere with the function of genes that regulate key biological processes, indeed, expands our understanding of the molecular machinery underlying medfly invasiveness. Furthermore, the ability to achieve germ-line transformation facilitates the production of multiple transgenic strains that can be tested for future field applications in novel SIT settings. Indeed, genetic manipulation can be used to confer desirable traits that can, for example, be used to monitor sterile male performance in the field, or that can result in early life-stage lethality. Here we describe a method to microinject nucleic acids into medfly embryos to achieve these two main goals.

Delivery of Nucleic Acids through Embryo Microinjection in the Worldwide Agricultural Pest Insect, Ceratitis capitata

The Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae) is a worldwide pest of agriculture. A deeper understanding of its biology is key to control medfly populations and thus reduce economic impact. Embryo microinjection is a fundamental tool allowing both germ-line transformation and reverse genetics studies in this species.

The Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a pest species with extremely high agricultural relevance. ...

Optogenetic Random Mutagenesis Using Histone-miniSOG in C. elegans

Forward genetic screening in model organisms is the workhorse to discover functionally important genes and pathways in many biological processes. In most mutagenesis-based screens, researchers have relied on the use of toxic chemicals, carcinogens, or irradiation, which requires designated equipment, safety setup, and/or disposal of hazardous materials. We have developed a simple approach to induce heritable mutations in C. elegans using germline-expressed histone-miniSOG, a light-inducible potent generator of reactive oxygen species. This mutagenesis method is free of toxic chemicals and requires minimal laboratory safety and waste management. The induced DNA modifications include single-nucleotide changes and small deletions, and complement those caused by classical chemical mutagenesis. This methodology can also be used to induce integration of extrachromosomal transgenes. Here, we provide the details of the LED setup and protocols for standard mutagenesis and transgene integration.

Optogenetic Random Mutagenesis Using Histone-miniSOG in C. elegans

Genetically-encoded histone-miniSOG induces genome-wide heritable mutations in a blue&#160;light-dependent manner. This mutagenesis method is simple, fast, free of toxic chemicals, and well-suited for forward genetic screening and transgene integration.

Forward genetic screening in model organisms is the workhorse to discover functionally important genes and pathways in many biological processes. In most ...

Rearing and Double-stranded RNA-mediated Gene Knockdown in the Hide Beetle, Dermestes maculatus

Advances in genomics have raised the possibility of probing biodiversity at an unprecedented scale. However, sequence alone will not be informative without tools to study gene function. The development and sharing of detailed protocols for the establishment of new model systems in laboratories, and for tools to carry out functional studies, is thus crucial for leveraging the power of genomics. Coleoptera (beetles) are the largest clade of insects and occupy virtually all types of habitats on the planet. In addition to providing ideal models for fundamental research, studies of beetles can have impacts on pest control as they are often pests of households, agriculture, and food industries. Detailed protocols for rearing and maintenance of D. maculatus laboratory colonies and for carrying out dsRNA-mediated interference in D. maculatus are presented. Both embryonic and parental RNAi procedures-including apparatus set up, preparation, injection, and post-injection recovery-are described. Methods are also presented for analyzing embryonic phenotypes, including viability, patterning defects in hatched larvae, and cuticle preparations for unhatched larvae. These assays, together with in situ hybridization and immunostaining for molecular markers, make D. maculatus an accessible model system for basic and applied research. They further provide useful information for establishing procedures in other emerging insect model systems.

Rearing and Double-stranded RNA-mediated Gene Knockdown in the Hide Beetle, Dermestes maculatus

Here, we present protocols for rearing an intermediate-germ beetle, Dermestes maculatus (D. maculatus) in the lab. We also share protocols for embryonic and parental RNAi and methods for analyzing embryonic phenotypes to study gene function in this species.

Advances in genomics have raised the possibility of probing biodiversity at an unprecedented scale. However, sequence alone will not be informative ...

Microinjection of CRISPR/Cas9 Protein into Channel Catfish, Ictalurus punctatus, Embryos for Gene Editing

The complete genome of the channel catfish, Ictalurus punctatus, has been sequenced, leading to greater opportunities for studying channel catfish gene function. Gene knockout has been used to study these gene functions in vivo. The clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system is a powerful tool used to edit genomic DNA sequences to alter gene function. While the traditional approach has been to introduce CRISPR/Cas9 mRNA into the single cell embryos through microinjection, this can be a slow and inefficient process in catfish. Here, a detailed protocol for microinjection of channel catfish embryos with CRISPR/Cas9 protein is described. Briefly, eggs and sperm were collected and then artificial fertilization performed. Fertilized eggs were transferred to a Petri dish containing Holtfreter's solution. Injection volume was calibrated and then guide RNAs/Cas9 targeting the toll/interleukin 1 receptor domain-containing adapter molecule (TICAM 1) gene and rhamnose binding lectin (RBL) gene were microinjected into the yolk of one-cell embryos. The gene knockout was successful as indels were confirmed by DNA sequencing. The predicted protein sequence alterations due to these mutations included frameshift and truncated protein due to premature stop codons.

Microinjection of CRISPR/Cas9 Protein into Channel Catfish, Ictalurus punctatus, Embryos for Gene Editing

A simple and efficient microinjection protocol for gene editing in channel catfish embryos using the CRISPR/Cas9 system is presented. In this protocol, guide RNAs and Cas9 protein were microinjected into the yolk of one-cell embryos. This protocol has been validated by knocking out two channel catfish immune-related genes.

The complete genome of the channel catfish, Ictalurus punctatus, has been sequenced, leading to greater opportunities for studying channel catfish gene ...

Embryo Microinjection and Transplantation Technique for Nasonia vitripennis Genome Manipulation

The jewel wasp Nasonia vitripennis has emerged as an effective model system for the study of processes including sex determination, haplo-diploid sex determination, venom synthesis, and host-symbiont interactions, among others. A major limitation of working with this organism is the lack of effective protocols to perform directed genome modifications. An important part of genome modification is delivery of editing reagents, including CRISPR/Cas9 molecules, into embryos through microinjection. While microinjection is well established in many model organisms, this technique is particularly challenging to perform in N. vitripennis primarily due to its small embryo size, and the fact that embryonic development occurs entirely within a parasitized blowfly pupa. The following procedure overcomes these significant challenges while demonstrating a streamlined, visual procedure for effectively removing wasp embryos from parasitized host pupae, microinjecting them, and carefully transplanting them back into the host for continuation and completion of development. This protocol will strongly enhance the capability of research groups to perform advanced genome modifications in this organism.

Embryo Microinjection and Transplantation Technique for Nasonia vitripennis Genome Manipulation

Microinjection of Nasonia vitripennis embryos is an essential method for generating heritable genome modifications. Described here is a detailed procedure for microinjection and transplantation of Nasonia vitripennis embryos, which will greatly facilitate future genome manipulation in this organism.

The jewel wasp Nasonia vitripennis has emerged as an effective model system for the study of processes including sex determination, haplo-diploid sex ...

Characterizing Histone Post-translational Modification Alterations in Yeast Neurodegenerative Proteinopathy Models

Neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and Parkinson&#39;s disease (PD), cause the loss of hundreds of thousands of lives each year. Effective treatment options able to halt disease progression are lacking. Despite the extensive sequencing efforts in large patient populations, the majority of ALS and PD cases remain unexplained by genetic mutations alone. Epigenetics mechanisms, such as the post-translational modification of histone proteins, may be involved in neurodegenerative disease etiology and progression and lead to new targets for pharmaceutical intervention. Mammalian in vivo and in vitro models of ALS and PD are costly and often require prolonged and laborious experimental protocols. Here, we outline a practical, fast, and cost-effective approach to determining genome-wide alterations in histone modification levels using Saccharomyces cerevisiae as a model system. This protocol allows for comprehensive investigations into epigenetic changes connected to neurodegenerative proteinopathies that corroborate previous findings in different model systems while significantly expanding our knowledge of the neurodegenerative disease epigenome.

This protocol outlines experimental procedures to characterize genome-wide changes in the levels of histone post-translational modifications (PTM) occurring in connection with the overexpression of proteins associated with ALS and Parkinson&#39;s disease in Saccharomyces cerevisiae models. After SDS-PAGE separation, individual histone PTM levels are detected with modification-specific antibodies via Western blotting.

Neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and Parkinson&#39;s disease (PD), cause the loss of hundreds of thousands of lives ...

Investigation of the Transcriptional Role of a RUNX1 Intronic Silencer by CRISPR/Cas9 Ribonucleoprotein in Acute Myeloid Leukemia Cells

The bulk of the human genome (~98%) is comprised of non-coding sequences. Cis-regulatory elements (CREs) are non-coding DNA sequences that contain binding sites for transcriptional regulators to modulate gene expression. Alterations of CREs have been implicated in various diseases including cancer. While promoters and enhancers have been the primary CREs for studying gene regulation, very little is known about the role of silencer, which is another type of CRE that mediates gene repression. Originally identified as an adaptive immunity system in prokaryotes, CRISPR/Cas9 has been exploited to be a powerful tool for eukaryotic genome editing. Here, we present the use of this technique to delete an intronic silencer in the human RUNX1 gene and investigate the impacts on gene expression in OCI-AML3 leukemic cells. Our approach relies on electroporation-mediated delivery of two preassembled Cas9/guide RNA (gRNA) ribonucleoprotein (RNP) complexes to create two double-strand breaks (DSBs) that flank the silencer. Deletions can be readily screened by fragment analysis. Expression analyses of different mRNAs transcribed from alternative promoters help evaluate promoter-dependent effects. This strategy can be used to study other CREs and is particularly suitable for hematopoietic cells, which are often difficult to transfect with plasmid-based methods. The use of a plasmid- and virus-free strategy allows simple and fast assessments of gene regulatory functions.

Investigation of the Transcriptional Role of a RUNX1 Intronic Silencer by CRISPR/Cas9 Ribonucleoprotein in Acute Myeloid Leukemia Cells

Direct delivery of preassembled Cas9/guide RNA ribonucleoprotein complexes is a fast and efficient means for genome editing in hematopoietic cells. Here, we utilize this approach to delete a RUNX1 intronic silencer and examine the transcriptional responses in OCI-AML3 leukemic cells.

The bulk of the human genome (~98%) is comprised of non-coding sequences. Cis-regulatory elements (CREs) are non-coding DNA sequences that contain binding ...

Embryo Microinjection Techniques for Efficient Site-Specific Mutagenesis in Culex quinquefasciatus

Culex quinquefasciatus is a vector of a diverse range of vector-borne diseases such as avian malaria, West Nile virus (WNV), Japanese encephalitis, Eastern equine encephalitis, lymphatic filariasis, and Saint Louis encephalitis. Notably, avian malaria has played a major role in the extinction of numerous endemic island bird species, while WNV has become an important vector-borne disease in the United States. To gain further insight into C. quinquefasciatus biology and expand their genetic control toolbox, we need to develop more efficient and affordable methods for genome engineering in this species. However, some biological traits unique to Culex mosquitoes, particularly their egg rafts, have made it difficult to perform microinjection procedures required for genome engineering. To address these challenges, we have developed an optimized embryo microinjection protocol that focuses on mitigating the technical obstacles associated with the unique characteristics of Culex mosquitoes. These procedures demonstrate optimized methods for egg collection, egg raft separation and other handling procedures essential for successful microinjection in C. quinquefasciatus. When coupled with the CRISPR/Cas9 genome editing technology, these procedures allow us to achieve site-specific, efficient and heritable germline mutations, which are required to perform advanced genome engineering and develop genetic control technologies in this important, but currently understudied, disease vector.

Embryo Microinjection Techniques for Efficient Site-Specific Mutagenesis in Culex quinquefasciatus

This protocol describes microinjection procedures for Culex quinquefasciatus embryos that are optimized to work with CRISPR/Cas9 gene editing tools. This technique can efficiently generate site-specific, heritable, germline mutations that can be used for building genetic technologies in this understudied disease vector.

Culex quinquefasciatus is a vector of a diverse range of vector-borne diseases such as avian malaria, West Nile virus (WNV), Japanese encephalitis, ...

Sand Fly (Phlebotomus papatasi) Embryo Microinjection for CRISPR/Cas9 Mutagenesis

Sand flies are the natural vectors for Leishmania species, protozoan parasites producing a broad spectrum of symptoms ranging from cutaneous lesions to visceral pathology. Deciphering the nature of the vector/parasite interactions is of primary importance for better understanding of Leishmania transmission to their hosts. Among the parameters controlling the sand fly vector competence (i.e. their ability to carry and transmit pathogens), parameters intrinsic to these insects were shown to play a key role. Insect immune response, for example, impacts sand fly vector competence to Leishmania. The study of such parameters has been limited by the lack of methods of gene expression modification adapted for use in these non-model organisms. Gene downregulation by small interfering RNA (siRNA) is possible, but in addition to being technically challenging, the silencing leads to only a partial loss of function, which cannot be transmitted from generation to generation. Targeted mutagenesis by CRISPR/Cas9 technology was recently adapted to the Phlebotomus papatasi sand fly. This technique leads to the generation of transmissible mutations in a specifically chosen locus, allowing to study the genes of interest. The CRISPR/Cas9 system relies on the induction of targeted double-strand DNA breaks, later repaired by either Non-Homologous End Joining (NHEJ) or by Homology Driven Repair (HDR). NHEJ consists of a simple closure of the break and frequently leads to small insertion/deletion events. In contrast, HDR uses the presence of a donor DNA molecule sharing homology with the target DNA as a template for repair. Here, we present a sand fly embryo microinjection method for targeted mutagenesis by CRISPR/Cas9 using NHEJ, which is the only genome modification technique adapted to sand fly vectors to date.

Sand Fly Phlebotomus papatasi Embryo Microinjection for CRISPR/Cas9 Mutagenesis

This protocol details the steps of CRISPR/Cas9 targeted mutagenesis in sand flies: embryo collection, injection, insect rearing, and identification as well as selection of mutations of interest.

Sand flies are the natural vectors for Leishmania species, protozoan parasites producing a broad spectrum of symptoms ranging from cutaneous lesions to ...

Microinjection Method for Anopheles gambiae Embryos

Embryo microinjection techniques are essential for many molecular and genetic studies of insect species. They provide a means to introduce exogenous DNA fragments encoding genes of interest as well as favorable traits into the insect germline in a stable and heritable manner. The resulting transgenic strains can be studied for phenotypic changes resulting from the expression of the integrated DNA to answer basic questions or used in practical applications. Although the technology is straightforward, it requires of the investigator patience and practice to achieve a level of skill that maximizes efficiency. Shown here is a method for microinjection of embryos of the African malaria mosquito, Anopheles gambiae. The objective is to deliver by microinjection exogenous DNA to the embryo so that it can be taken up in the developing germline (pole) cells. Expression from the injected DNA of transposases, integrases, recombinases, or other nucleases (for example CRISPR-associated proteins, Cas) can trigger events that lead to its covalent insertion into chromosomes. Transgenic An. gambiae generated from these technologies have been used for basic studies of immune system components, genes involved in blood-feeding, and elements of the olfactory system. In addition, these techniques have been used to produce An. gambiae strains with traits that may help control the transmission of malaria parasites.

Microinjection Method for Anopheles gambiae Embryos

Microinjection techniques are essential to introduce exogenous genes into the genomes of mosquitoes. This protocol explains a method used by the James laboratory to microinject DNA constructs into Anopheles gambiae embryos to generate transformed mosquitoes.

Embryo microinjection techniques are essential for many molecular and genetic studies of insect species. They provide a means to introduce exogenous DNA ...