Name: ploidy manipulation of zebrafish embryos with heat shock 2 treatment
Uploaded: 2016-12-16T13:00:00
Description: Watch this Scientific Journal Video about Ploidy Manipulation of Zebrafish Embryos with Heat Shock 2 Treatment at JoVE.com

This work was supported by NIH grants R21 HD068949-01 and RO1 GM065303.

All animal experiments were conducted according to University of Wisconsin &#8211; Madison and Institutional Animal Care and Use Committee (IACUC) guidelines (University of Wisconsin &#8211; Madison Assurance number A3368-01).
1. Selecting Females for Egg Collection via Interrupted Mating
NOTE: IVF-based protocols rely on the extrusion of mature eggs from females through manual pressure 9. Previous protocols have used females directly from tanks or in pair matings without the females undergoing egg...

<ol>
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Biol. 20, 2040-2045 (2010).</li><li>Yabe, T., Ge, X., Pelegri, 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+zebrafish+maternal-effect+gene+cellular+atoll+encodes+the+centriolar+component+Sas-6+and+defects+in+its+paternal+function+promote+whole+genome+duplication.">The zebrafish maternal-effect gene cellular atoll encodes the centriolar component Sas-6 and defects in its paternal function promote whole genome duplication.</a> Dev. Biol. 312, 44-60 (2007).</li><li>Poss, K. D., Nechiporuk, A., Stringer, K. F., Lee, C., Keating, M. 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Critical steps
It is critical to work under conditions of effective in vitro fertilization. To insure a good supply of mature eggs (step 1), females set up for mating should not have been set up in mating crosses for at least 5 days and should appear gravid. During interruption of breeding, an observer can monitor 15-30 tanks adequately for the first appearance of natural egg extrusion. Interruption of mating should occur as soon as possible when the first eggs are released through natural mating...

This protocol allows the manipulation of ploidy in zebrafish embryos, such as in the generation of homozygous gynogenetic diploids from gynogenetic haploids (Figure 1) or the production of tetraploids. This is achieved by inducing a delay in cytokinesis corresponding to precisely one cell cycle (Figure 2A, 2B). The key one-cycle delay in cytokinesis is achieved by treatment with heat shock. The standard protocol of Heat Shock (HS) as originally described by Streisinger and colleagues involved a temperature pulse during the period 13-15 mpf, resulting in a one-cycle cell division stall during the first cell cycle 1. The efficiency of this protocol has been recently improved by scanning the early cell cycles with a sliding temporal window of heat shock treatment. This scan identified a later time point for a heat shock, still within the first cell cycle (22-24 mpf), that results in a higher rate of embryos with a one-cycle cell division stall, which in this case affects the second cell cycle 2. The observation that experimental manipulations during the first cell cycle interfere with cell division during the second cell cycle and cause DNA content duplication has also been reported in other fish species 3,4. We refer to this modified protocol as Heat Shock 2 (HS2 &#8211; the term &#34;2&#34; reflects that the heat pulse occurs at a later time point than the standard HS method, and that the cell cycle delay caused by HS2 occurs during the second cell cycle). These studies showed that the basis for cytokinesis arrest after heat shock is the inhibition of centriole duplication during the heat pulse, which affects spindle formation and furrow induction in the following cell cycle. HS2 results in yields of cell cycle arrest nearing 100%, and rates of ploidy duplication up to 4 times higher than standard HS 2.
Embryos treated with a heat shock during blastomere cell cycling exhibit many deleterious effects, suggesting that heat shock affects multiple processes required for cell division 2. On the other hand, if the heat shock is applied prior to the initiation of cell cycling (time period 0-30 mpf), it appears to have effects consistent with specific interference with centriole duplication and does not seem to affect other essential cell processes 2. These studies showed that the time prior to the initiation of blastomere division appears to be a developmental period amenable to using Heat Shock as a tool to specifically manipulate ploidy through centriole inhibition. The underlying cause of the apparent selectivity for heat shock on centriole duplication is unknown, but may be related to a selective degradation of centrosome substructures observed under heat stress in certain cell types, such as leukocytes 5.
Temporal synchronization of embryonic development is achieved by in vitro fertilization (IVF). Use of untreated sperm during fertilization results in diploid embryos that upon HS2-induced one-cycle cytokinesis stall become tetraploid. Use of UV-treated sperm, which carries crosslinks that inactivate its DNA, results in gynogenetic haploid embryos 6, which upon HSII-induced one-cycle cytokinesis stall become gynogenetic diploids 2. Because of the resulting whole genome duplication, the latter gynogenetic diploids are homozygous at every single locus across the genome. For conciseness, we refer to gynogenetic haploid embryos as &#34;haploids&#34;, and homozygous gynogenetic diploid embryos as &#34;homozygous diploids&#34;. If viable and fertile, homozygous diploids can be used to initiate sterile and lethal-free lines. Direct homozygosity induced by HS2 should also be readily incorporated into genetic analysis or genetic screens, since homozygous diploids from females that are heterozygous carriers of mutations exhibit rates of homozygosity at high and fixed (50%) ratios 2.
The following protocol describes steps to perform HS2 and induce ploidy duplication with full homozygosity. For tetraploid production, sperm solution should be untreated. For homozygous diploid production, sperm should be inactivated by UV treatment. In addition, as described in the Discussion, visible pigment markers can also be used to facilitate identification of homozygous diploids. Zebrafish mate primarily during the first 3 hr of the initiation of their light cycle 7, and both adults and eggs are sensitive to circadian rhythms 8, so for best results the IVF procedure should occur within this time period.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<colgroup>
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		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Zebrafish mating boxes</td>
			<td style="width:71px;">Aqua Schwarz</td>
			<td style="width:119px;">SpawningBox1</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaCl</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">S5886</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">KCl</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">P5405</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Na2HPO4</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">S3264</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">KH2PO4</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">P9791</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CaCl2</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">C7902</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">MgSO4-7H2O</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">63138</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaHCO3</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">S5761</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Tricaine</td>
			<td style="width:71px;">Western Chemical</td>
			<td style="width:119px;">Tricaine-D (MS 222)</td>
			<td>FDA approved (ANADA 200-226)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tris base</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">77-86-1</td>
			<td>to prepare 1 M Tris pH 9.0</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HCl</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">920-1</td>
			<td>to prepare 1 M Tris pH 9.0</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Fish net (fine mesh) (4-5 in)</td>
			<td style="width:71px;">PennPlax</td>
			<td style="width:119px;">(ThatFishThatPlace # 212370)</td>
			<td>available in ThatFishThatPlace</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Plastic spoon</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>available in most standard stores</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Dissecting scissors</td>
			<td style="width:71px;">Fine Science Tools</td>
			<td style="width:119px;">14091-09</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Dissecting forceps</td>
			<td style="width:71px;">Dumont</td>
			<td style="width:119px;">SS</td>
			<td>available from Fine Science Tools</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dissecting stereoscope (with transmitted light source)</td>
			<td style="width:71px;">Nikon</td>
			<td style="width:119px;">SMZ645</td>
			<td>or equivalent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Reflective light source (LED arms)</td>
			<td style="width:71px;">Fostec</td>
			<td style="width:119px;">KL1600 LED</td>
			<td>or equivalent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Petri plates 10 cm diameter</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Eppendorf tubes 1.5 ml</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ice bucket</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Pipetteman P-1000</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Pipette tips 1000 &#181;l</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Narrow spatula</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">14-374</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Depression glass plate</td>
			<td style="width:71px;">Corning Inc</td>
			<td style="width:119px;">722085 (Fisher cat. No 13-748B)</td>
			<td>available from Fisher Scientific</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">UV lamp</td>
			<td style="width:71px;">UVP</td>
			<td style="width:119px;">Model XX-15 (cat No. UVP18006201)</td>
			<td>available from Fisher Scientific. Although not observed by us with this model, some UV sources have been observed to experience a decrease of intensity over time (if this is the case, see Modifications and Troubleshooting)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">UV glasses</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Paper towels</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Kimwipes</td>
			<td style="width:71px;">Kimberly-Clark</td>
			<td style="width:119px;">06-666-11</td>
			<td>available from Fisher Scientific</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Timer stop watch</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Wash bottle</td>
			<td style="width:71px;">Thermo Scientific</td>
			<td style="width:119px;">24020500</td>
			<td>available from Fisher Scientific</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tea strainer</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>available in kitchen stores</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">beakers, 250 ml (2)</td>
			<td style="width:71px;">Corning Inc.</td>
			<td style="width:119px;">1000250</td>
			<td>available from Fisher Scientific</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">water bath (2)</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>any maker, with accurary to 0.1 C (e.g. Shel Lab H2O Bath Series)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="44">
			<td height="44" style="height:44px;">Hanks&#8217; Solution 1</td>
			<td style="width:71px;">see above</td>
			<td style="width:119px;">see above</td>
			<td>8.0g NaCl, 0.4g KCl in 100ml ddH2O. Store at 4&#176;C.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hanks&#8217; Solution 2</td>
			<td style="width:71px;">see above</td>
			<td style="width:119px;">see above</td>
			<td>0.358g Anhydrous Na2HPO4, 0.6g KH2PO4 in 100ml ddH2O. Store at 4&#176;C.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hanks&#8217; Solution 4</td>
			<td style="width:71px;">see above</td>
			<td style="width:119px;">see above</td>
			<td>0.72g CaCl2 in 50ml ddH2O. Store at 4&#176;C.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hanks&#8217; Solution 5</td>
			<td style="width:71px;">see above</td>
			<td style="width:119px;">see above</td>
			<td>1.23g MgSO4 &#8729; 7H2O in 50ml ddH2O. Store at 4&#176;C.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hank&#39;s Premix</td>
			<td style="width:71px;">see above</td>
			<td style="width:119px;">see above</td>
			<td>add, in the following order: 10.0 ml Solution 1;&#160; 1.0 ml Solution 2;&#160; 1.0 ml Solution 4;&#160; 86.0 ml ddH2O;&#160; 1.0 ml Solution 5. Store at 4&#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hanks&#8217; Solution 6</td>
			<td style="width:71px;">see above</td>
			<td style="width:119px;">see above</td>
			<td>0.33g NaHCO3 in 10ml ddH2O. Prepare fresh the morning of the IVF procedure.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hank&#39;s Solution (final solution)</td>
			<td style="width:71px;">see above</td>
			<td style="width:119px;">see above</td>
			<td>Combine 990ul of Hank&#8217;s Premix and 10ul of freshly made Solution 6 (NaHCO3 solution)</td>
		</tr>
	</tbody>
</table>

ploidy manipulation of zebrafish embryos with heat shock 2 treatment

Manipulation of ploidy allows for useful transformations, such as diploids to tetraploids, or haploids to diploids. In the zebrafish Danio rerio, specifically the generation of homozygous gynogenetic diploids is useful in genetic analysis because it allows the direct production of homozygotes from a single heterozygous mother. This article describes a modified protocol for ploidy duplication based on a heat pulse during the first cell cycle, Heat Shock 2 (HS2). Through inhibition of centriole duplication, this method results in a precise cell division stall during the second cell cycle. The precise one-cycle division stall, coupled to unaffected DNA duplication, results in whole genome duplication. Protocols associated with this method include egg and sperm collection, UV treatment of sperm, in vitro fertilization and heat pulse to cause a one-cell cycle division delay and ploidy duplication. A modified version of this protocol could be applied to induce ploidy changes in other animal species.

In spite of the one-cell cycle cytokinesis stall, DNA replication occurs normally in such embryos, resulting in the duplication of the DNA content of the embryo (Figure 1). The Streisinger Heat Shock protocol (standard HS) involves a heat pulse during the period 13-15 minutes post fertilization (mpf) and induces primarily cytokinesis arrest during the first embryonic cell division at 35 mpf 1,2, whereas the derived method described here, referred to as Heat Sho...

Watch this Scientific Journal Video about Ploidy Manipulation of Zebrafish Embryos with Heat Shock 2 Treatment at JoVE.com

Ploidy Manipulation of Zebrafish Embryos with Heat Shock 2 Treatment

A modified protocol for ploidy manipulation uses a heat shock to induce a one-cycle stall in cytokinesis in the early embryo. This protocol is demonstrated in the zebrafish but may be applicable to other species.

Manipulation of ploidy allows for useful transformations, such as diploids to tetraploids, or haploids to diploids. In the zebrafish Danio rerio, ...

The overall goal of this procedure is to promote diploidization in the early zebrafish embryo through inhibition of cytokinesis corresponding to one embryonic cell cycle. This method can help answer key questions in the field of genetics such as through the identification of genes involved in adult or reproductive traits, the generation of inbred lines or other genetic manipulations. The main advantage of this technique is that it is simple yet effective in promoting diploidization, allowing the direct homozygosis of alleles present in a single heterozygous individual.The afternoon before the experiment, set up mating pairs of the desired zebrafish strain in standard zebrafish mating boxes with dividers to separate males and females. The morning of the experiment, remove the physical partition for egg laying to begin. Visually inspect tanks containing mating pairs to detect extrusion of eggs during natural mating.At the first signs of egg extrusions, separate the male and female to interrupt breeding. Keep the pre-selected females either separately or pooled in the same tank. Use multiple females depending on the number of embryos desired.To prepare a sperm solution from zebrafish testes, after confirming euthanasia according to the text protocol, remove the males from the beaker. Use conditioned water to rinse briefly and dry them lightly by briefly placing them on several locations of paper towel. Use dissecting scissors or a razor blade to decapitate the fish and make a longitudinal cut along the abdomen.Then under a dissecting microscope with a reflected light source, use dissecting forceps to remove the internal organs. Pull out each of the testes'masses and transfer them to a microcentrifuge tube with Hank solution. To release the sperm into the solution, use a narrow spatula to shear the testes or use a 1, 000 microliter tip and pipette up and down five to six times in the solution while avoiding air bubble formation.Then allow the testes debris to settle. Store the sperm solution on ice where it can keep its potency for two to three hours. If proceeding to UV sperm treatment, transfer the sperm solution to a clean microcentrifuge tube leaving the sperm debris behind.To carry out UV treatment of sperm, transfer up to one milliliter of the sperm solution to a clean dry well of a depression glass plate sitting on an ice bed. Place the ice bed with the depression plate under a UV lamp at a distance of 19 centimeters from the light source and treat the sperm solution at 115 volts for 90 seconds. With the end of an unused pipette tip, gently mix the solution every 30 seconds during UV treatment.Using a clean pipette tip on a micropipette, transfer the treated sperm solution to a new microcentrifuge tube. Store on ice no longer than two to three hours until needed for IVF. After anesthetizing female zebrafish according to the text protocol, as soon as the fish stops gill movement, use a spoon to collect the fish and use conditioned water to briefly rinse it.With the spoon moving from the anterior to the posterior of the fish to avoid damaging the gill operculum, place the fish briefly and repeatedly on several locations of a paper towel to lightly dry it. Then transfer it to a clean 10 centimeter diameter Petri dish. Use lab wipes or soft tissue to further gently dry the anal fin area to prevent any released eggs from prematurely being activated by water.Then after lightly dampening the fingers with water, place one finger of one hand on the female's back as support and with the finger on the other hand, apply slight pressure along the female's abdomen until eggs are extruded. It is crucial that the extruded eggs do not encounter any excess water to avoid them from becoming prematurely activated which would prevent them from becoming fertilized by sperm. Use a narrow spatula to move the eggs away from the female's body.Then place the female back into a tank with conditioned water for recovery. Within 90 seconds after egg extrusion, add 100 microliters of sperm solution to the extruded eggs in a Petri dish. Gently swirl the pipette tip among the eggs to mix the sperm and eggs together, being sure not to lift the tip from the surface of the Petri dish to avoid egg damage.Immediately activate the eggs by adding approximately one milliliter of embryonic or E3 medium and again gently mix the eggs and sperm by using a pipette tip to swirl. Initiate timing relative to fertilization. At one minute post fertilization in the one milliliter volume, use E3 to flood the plate.Leave the fertilized eggs undisturbed until 10 to 12 minutes post fertilization or MPF to allow egg activation including full chorion expansion. After expansion of the chorions, pour the embryos from the Petri dish into a tea strainer. Then use a wash bottle with E3 to rinse the Petri dish to collect any remaining eggs into the strainer.Place the tea strainer with the embryos inside a beaker in a pre-heated bath with E3 at 28.5 degrees Celsius. Pre-equilibrate the beaker and E3 to the water bath temperature and make sure there is enough E3 so that all embryos in the strainer are submerged. At 22 MPF, remove the tea strainer from the water bath then briefly blot it onto a paper towel to remove excess moisture and place it inside a similarly pre-heated E3 beaker in a heat bath at 41.4 degrees Celsius.The key step in the procedure is the heat shock which induces a one-cycle delay in the cell division and therefore hold genome duplication. At 24 MPF, briefly blot the strainer and transfer it back into the E3 in a 28.5 degrees Celsius water bath. Then at 29 MPF, use a wash bottle with E3 to transfer the embryos from the tea strainer to a 10 centimeter Petri plate.Between 35 to 45 MPF, under a dissecting microscope with a transmitted light source, select embryos that are undergoing symmetrical cleavage into the two-cell stage and which were therefore fertilized. Remove embryos that are not undergoing cell cleavage. Continue observing the fertilized embryos selected for normal cell division during the first cell cycle and during the second cell cycle.Sort embryos according to the following categories. Four cells or no stall in the two to two arrangement standard for a four-cell embryo, three cells or partial stall in an aberrant two smaller cells to one large cell arrangement and two cells or stalled embryos. Sort the stalled embryos into a fresh Petri plate.Allow up to 80 embryos to develop in the Petri dish. At 24 hours post fertilization or HPF, observe the embryos to determine whether they have a normal morphology characteristic of diploid or homozygous diploid embryos. In contrast to reduced axis extension, an increased body thickness characteristic of haploids.In addition, at 36 HPF, assess diploidization using genetic pigment markers and other assays such as golden or albino. Finally, remove any embryos that appear to have a haploid morphology or that have lysed or exhibit other grossly abnormal defects. The derived method demonstrated here, referred to as HS2, uses a heat shock during the period 22 to 24 MPF and induces cytokinesis arrest during the second embryonic cell division at 50 MPF.During the stall, ongoing DNA synthesis result in embryos undergoing diploidization from either haploid to diploid or diploid to tetraploid. HS2 treated embryos can exhibit a variety of blastomere arrangements including no stall where neither blastomere exhibits a delay, a partial stall where one of the two blastomeres is delayed and stalled where both blastomeres exhibit delays. The morphology of the embryos can be determined at 24 HPF with a normal morphology characteristic of diploid or homozygous diploid embryos or the shorter and wider body axis morphology characteristic of haploid embryos.If properly selected for a one-cell cycle delay, all embryos should exhibit a normal diploid morphology. Once mastered, this technique can be done in two hours if it is performed properly. Although, it will take more time to process multiple clutches.While attempting this procedure, it is important to remember to separate females in time, dissect testes accurately, avoid prematurely contact of extruded eggs with water and keep proper timing of the fertilized clutches. Following this procedure, other methods like forward genetic screens can be performed in order to answer additional questions like what genes are involved in specific biological functions. After its development, this technique paved the way for researchers in the field of genetics to explore traits relevant to juvenile, adult and intergenerational traits in the zebrafish.After watching this video, you should have a good understanding of how to use heat treatment to induce diploidization in zebrafish. Don't forget that working with UV light can be extremely hazardous and precautions such as wearing UV protective safety glasses should always be taken while performing this procedure.

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