Research reported in this project was supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under grant number P20GM10342 to HH3, and by NSF award number IOS-1257217 to CGE.

1. Hardware Setup and Preparation of Materials
NOTE: Please see Table 1 and Table of Materials for preparation of solutions, reagent, and equipment details.
<ol>
	<li>Set up a dissecting microscope in order to see eggs and guide the injection needle. (Figure 1A shows a dissecting microscope equipped with fluorescence.) Fluorescence capability is advantageous but not necessary.</li>
	<li>Position a 3-axis microma...

<ol>
	<li>Abzhanov, A., 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=Are+we+there+yet?+Tracking+the+development+of+new+model+systems.">Are we there yet? Tracking the development of new model systems.</a> Trends in Genetics. 24 (7), 353-360 (2008).</li><li>Krebs, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+August+Krogh+principle:+&#8220;For+many+problems+there+is+an+animal+on+which+it+can+be+most+conveniently+studied.">The August Krogh principle: &#8220;For many problems there is an animal on which it can be most conveniently studied.</a> Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 194 (1), 221-226 (1975).</li><li>Krogh, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Progress+of+Physiology.">The Progress of Physiology.</a> American Journal of Physiology. 90 (2), 243-251 (1929).</li><li>Huber, F., Moore, T. E., Loher, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cricket neurobiology and behavior. , (1989).</li><li>Horch, H. W., Mito, T., Popadic, A., Ohuchi, H., Noji, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Cricket as a Model Organism: Development, Regeneration, and Behavior. , (2017).</li><li>Misof, 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=Phylogenomics+resolves+the+timing+and+pattern+of+insect+evolution.">Phylogenomics resolves the timing and pattern of insect evolution.</a> Science. 346 (6210), 763-767 (2014).</li><li>Nakamura, 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=Imaging+of+transgenic+cricket+embryos+reveals+cell+movements+consistent+with+a+syncytial+patterning+mechanism.">Imaging of transgenic cricket embryos reveals cell movements consistent with a syncytial patterning mechanism.</a> Current Biology. 20 (18), 1641-1647 (2010).</li><li>Shinmyo, Y., 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=piggyBac-mediated+somatic+transformation+of+the+two-spotted+cricket,+Gryllus+bimaculatus.">piggyBac-mediated somatic transformation of the two-spotted cricket, Gryllus bimaculatus.</a> Development, growth &amp; differentiation. 46 (4), 343-349 (2004).</li><li>Watanabe, 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=Non-transgenic+genome+modifications+in+a+hemimetabolous+insect+using+zinc-finger+and+TAL+effector+nucleases.">Non-transgenic genome modifications in a hemimetabolous insect using zinc-finger and TAL effector nucleases.</a> Nature communications. 3, 1017 (2012).</li><li>Wang, H., La Russa, M., Qi, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRISPR/Cas9+in+Genome+Editing+and+Beyond.">CRISPR/Cas9 in Genome Editing and Beyond.</a> Annual Review of Biochemistry. 85 (1), 227-264 (2016).</li><li>Awata, H., Watanabe, T., Hamanaka, Y., Mito, T., Noji, S., Mizunami, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Knockout+crickets+for+the+study+of+learning+and+memory:+Dopamine+receptor+Dop1+mediates+aversive+but+not+appetitive+reinforcement+in+crickets.">Knockout crickets for the study of learning and memory: Dopamine receptor Dop1 mediates aversive but not appetitive reinforcement in crickets.</a> Scientific Reports. 5, 15885 (2015).</li><li>Horch, H. W., Liu, J. J., Mito, T., Popadic, A., Watanabe, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protocols+in+the+Cricket.">Protocols in the Cricket.</a> The Cricket as a Model Organism: Development, Regeneration, and Behavior. , 327-370 (2017).</li><li>Watanabe, T., Noji, S., Mito, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome+Editing+in+the+Cricket,+Gryllus+bimaculatus.">Genome Editing in the Cricket, Gryllus bimaculatus.</a> Genome Editing in Animals. , 219-233 (2017).</li><li>Kainz, F., Ewen-Campen, B., Akam, M., Extavour, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Notch/Delta+signalling+is+not+required+for+segment+generation+in+the+basally+branching+insect+Gryllus+bimaculatus.">Notch/Delta signalling is not required for segment generation in the basally branching insect Gryllus bimaculatus.</a> Development. 138 (22), 5015-5026 (2011).</li><li>Miyawaki, K., 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=Involvement+of+Wingless/Armadillo+signaling+in+the+posterior+sequential+segmentation+in+the+cricket,+Gryllus+bimaculatus+(Orthoptera),+as+revealed+by+RNAi+analysis.">Involvement of Wingless/Armadillo signaling in the posterior sequential segmentation in the cricket, Gryllus bimaculatus (Orthoptera), as revealed by RNAi analysis.</a> Mechanisms of Development. 121 (2), 119-130 (2004).</li><li>Donoughe, S., Kim, C., Extavour, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+live-imaging+of+embryos+in+microwell+arrays+using+a+modular+specimen+mounting+system.">High-throughput live-imaging of embryos in microwell arrays using a modular specimen mounting system.</a> Biology Open. 7 (7), bio031260 (2018).</li><li>Donoughe, S., Nakamura, T., Ewen-Campen, B., Green, D. A., Henderson, L., Extavour, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BMP+signaling+is+required+for+the+generation+of+primordial+germ+cells+in+an+insect.">BMP signaling is required for the generation of primordial germ cells in an insect.</a> Proceeding of the National Academy of Science USA. 111 (11), 4133-4138 (2014).</li><li>Larson, E., Andres, J., Harrison, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+the+male+ejaculate+on+post-mating+prezygotic+barriers+in+field+crickets.">Influence of the male ejaculate on post-mating prezygotic barriers in field crickets.</a> PLOS ONE. 7 (10), e46202 (2012).</li><li>Donoughe, S., Extavour, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+development+of+the+cricket+Gryllus+bimaculatus.">Embryonic development of the cricket Gryllus bimaculatus.</a> Developmental Biology. , (2016).</li><li>Matsuoka, Y., 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=Short+germ+insects+utilize+both+the+ancestral+and+derived+mode+of+Polycomb+group-mediated+epigenetic+silencing+of+Hox+genes.">Short germ insects utilize both the ancestral and derived mode of Polycomb group-mediated epigenetic silencing of Hox genes.</a> Biology Open. 4 (6), 702-709 (2015).</li><li>Rosenberg, M., Lynch, J., Desplan, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heads+and+tails:+Evolution+of+antero-posterior+patterning+in+insects.">Heads and tails: Evolution of antero-posterior patterning in insects.</a> Biochimica et biophysica acta. 1789 (4), 333-342 (2009).</li><li>Bacon, J., Strausfeld, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonrandom+resolution+of+neuron+arrangements.">Nonrandom resolution of neuron arrangements.</a> Neuroanatomical Techniques: Insect Nervous System. , 357-372 (1980).</li></ol>

The authors have nothing to disclose.

The two main challenges with this technique are the related issues of optimal needle size and survivability. Though smaller needles improve survivability, needles with narrower lumens have a greater degree of capillary forces at work, which makes it more likely that yolk will move into the needle causing it to clog. In the best case, blockages can be cleared simply by injecting another egg or by clearing the needle as described above. One can also attempt to increase the balance pressure on the microinjector until the yo...

The ability to modify the genome or influence gene expression in organisms is the basis for the design of many types of experiments testing functional causality. It is also critical for the comparative and evolutionarily-relevant work that genomic and non-genomic modification techniques be available in organisms outside traditional genetic laboratory animal model systems (e.g., Mus musculus, Danio rerio, Drosophila melanogaster, and Caenorhabditis elegans). Whether it is the desire to understand organismal diversity1 or one&#39;s adherence to Krogh&#39;s principle, that for every biological question there is an organism best suited to its solution2,3, the ability to modify genomes or influence the gene expression is essential for modern experimental designs.
The cricket Gryllus bimaculatus is an emerging model system. Used for the last century in neuroethology experiments4, the last two decades have witnessed an increased experimental interest in the cricket, particularly focused on the evolution and development of this organism5. The cricket is a hemimetabolous insect that branches basally to well-studied holometabolous insects, such as D. melanogaster and Tribolium castaneum6. Due to its useful position on the evolutionary tree, scientists are interested in asking modern, sophisticated experimental questions in this insect, which has led to a growing interest in adapting molecular tools for the use in G. bimaculatus.
Injections of molecular reagents into cricket eggs can be used for genomic modification experiments as well as non-genomic manipulations of gene expression in embryos. For example, transgenic G. bimaculatus carrying eGFP insertions have been created using the transposase piggyBac7,8. Investigators have successfully created knockout G. bimaculatus using Zinc-finger nucleases (ZFNs) and transcription activator-like (TAL) effector nucleases (TALENs) to introduce double-stranded breaks in specific genomic regions9. Though ZFNs and TALENs allow site-specific targeting in animals beyond the big four model systems, these reagents have quickly been surpassed by the CRISPR/Cas9 system, which is simpler to use, more efficient, and highly flexible10. CRISPR has been used in G. bimaculatus to produce knock-out11 as well as knock-in lines12,13 In addition to genomic modification, dsRNA can be injected into eggs to knock down mRNA expression in developing embryos, allowing investigators to understand the role of specific transcripts throughout development14,15. Some limited details on how to inject cricket eggs have been published previously12.
Here, we describe a detailed protocol for injecting early G. bimaculatus eggs. This protocol is effective and easily adaptable to various laboratory settings, injection materials, and possibly to other insects. While additional details for designing and implementing genomic modification and knockdown experiments have been published elsewhere12,13, these approaches will ultimately rely on the injection protocol detailed here.

<table>
	<tbody>
		<tr>
			<td>Fluorescent dissecting microscope</td>
			<td>Leica</td>
			<td>M165 FC</td>
			<td>Stereomicroscope with fluorescence</td>
			<td></td>
		</tr>
		<tr>
			<td>External light source for fluorescence</td>
			<td>Leica</td>
			<td>EL 6000</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microinjector</td>
			<td>Narishige</td>
			<td>IM-300</td>
			<td>-Accessories may include Injection Needles Holder, Input Hose (with a hose connector), AC Power Cord, Foot Switch, Silicone Rubber Gasket-</td>
			<td></td>
		</tr>
		<tr>
			<td>mCherry filter cube</td>
			<td>Leica</td>
			<td>M205FA/M165FC</td>
			<td>Filter cube for mCherry or similar red dye will work</td>
			<td></td>
		</tr>
		<tr>
			<td>Micromanipulator</td>
			<td>World Precision Instruments, Inc.</td>
			<td>M3301R</td>
			<td>Used with Magnetic Stand (Narishige, Type GJ-8)</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic stand</td>
			<td>Narishige</td>
			<td>MMO-202ND</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette Holder (Needle holder)</td>
			<td>Narishige</td>
			<td>HD-21</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="2">Tubing to connect air source to microinjector</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Egg well stamp</td>
			<td>3D printed</td>
			<td>custom</td>
			<td>3D printed on a Lulzbot Taz 5 using Poly Lactic Acid thermoplastic</td>
			<td></td>
		</tr>
		<tr>
			<td>Microwave</td>
			<td>various</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Incubator or temperature controlled room</td>
			<td>various</td>
			<td></td>
			<td>Temperatures of 23.5-26&#176;C are needed.</td>
			<td></td>
		</tr>
		<tr>
			<td>cricket food</td>
			<td>various</td>
			<td></td>
			<td>cat food or fish flakes are appropriate food.&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>cricket wter</td>
			<td>vairous</td>
			<td></td>
			<td>Water can be held in vials and presented to crickets through cotton balls</td>
			<td></td>
		</tr>
		<tr>
			<td>cricket shelter</td>
			<td>arious</td>
			<td></td>
			<td>Shelter materials can include crumpled paper towels or egg cartons</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass capillary tubes</td>
			<td>World Precision Instruments, Inc.</td>
			<td>Item no. 1B100F-4</td>
			<td>Kwik-Fil&#8482; Borosilicate Glass Capillaries, 100mm length, 0.58 mm ID, 1.0 mm OD, with filament</td>
			<td></td>
		</tr>
		<tr>
			<td>Micropipette puller</td>
			<td>Flaming/Brown</td>
			<td>Model P-97</td>
			<td>Distributed by Sutter Instrument Co.</td>
			<td></td>
		</tr>
		<tr>
			<td>Beveller/Micro grinder</td>
			<td>Narishige</td>
			<td>Model EG-45/EG-400</td>
			<td>EG-400 includes a microscope head</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri dishes</td>
			<td>CellTreat</td>
			<td>Product code 229693</td>
			<td>90mm diameter</td>
			<td></td>
		</tr>
		<tr>
			<td>Play Sand</td>
			<td>Sandtastik Products Ltd.</td>
			<td>B003U6QLVS</td>
			<td>White play sand</td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>American Bioanalytical</td>
			<td>AB000972</td>
			<td>Agarose GPG/LE ultrapure</td>
			<td></td>
		</tr>
		<tr>
			<td>Egg Strainer: Extra Fine Twill Mesh Stainless Steel Conical Strainers</td>
			<td>US Kitchen Supply</td>
			<td>Model SS-C123</td>
			<td>Pore size should be between 0.5 - 1.0 mm</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin Streptomycin</td>
			<td>Gibco by Life Technologies</td>
			<td>Ref 15070-063</td>
			<td>Pen Strep</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic tweezers</td>
			<td>Sipel Electronic SA</td>
			<td>P3C-STD</td>
			<td>Black Static Dissipative, 118mm</td>
			<td></td>
		</tr>
		<tr>
			<td>syringe filters, 25mm diameter, 0.45 &#181;m</td>
			<td>Nalgene</td>
			<td>725-2545</td>
			<td>Use with 1 ml syringe</td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL syringe, with Tuberculin Slip Tip</td>
			<td>Becton Dickinson</td>
			<td>309602</td>
			<td>Use with syring filter to filter Injection Buffer , Luer-Lok tip syringes would also work</td>
			<td></td>
		</tr>
		<tr>
			<td>Air tank (optional)</td>
			<td>Midwest Products</td>
			<td>Air Works&#174;</td>
			<td>Portable air tank</td>
			<td></td>
		</tr>
		<tr>
			<td rowspan="2">Rhodamine dye</td>
			<td rowspan="2">Thermofisher</td>
			<td rowspan="2">D-1817</td>
			<td rowspan="2">dextran, tetramethylrhodamine 10,000MW,</td>
			<td></td>
		</tr>
		<tr>
			<td>20 mL loading tips</td>
			<td>Eppendorf</td>
			<td>Order no. 5242 956.003</td>
			<td>epT.I.P.S. 20uL Microloader</td>
			<td></td>
		</tr>
		<tr>
			<td>Compound microscope</td>
			<td>Zeiss</td>
			<td>Axioskope 2 plus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>20X objective</td>
			<td>Ziess</td>
			<td>Plan-Apochromat 20x/0.75 M27</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>camera</td>
			<td>Leica</td>
			<td>DMC 5400</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Leica Application Suite&#160; software</td>
			<td>Leica</td>
			<td>LAS</td>
			<td>Version 4.6.2 used here</td>
			<td></td>
		</tr>
	</tbody>
</table>

injecting gryllus bimaculatus eggs

Altering gene function in a developing organism is central to different kinds of experiments. While tremendously powerful genetic tools have been developed in traditional model systems, it is difficult to manipulate genes or messenger RNA (mRNA) in most other organisms. At the same time, evolutionary and comparative approaches rely on an exploration of gene function in many different species, necessitating the development and adaptation of techniques for manipulating expression outside currently genetically tractable species. This protocol describes a method for injecting reagents into cricket eggs to assay the effects of a given manipulation on embryonic or larval development. Instructions for how to collect and inject eggs with beveled needles are described. This relatively straightforward technique is flexible and potentially adaptable to other insects. One can gather and inject dozens of eggs in a single experiment, and survival rates for buffer-only injections improve with practice and can be as high as 80%. This technique will support several types of experimental approaches including injection of pharmacological agents, in vitro capped mRNA to express genes of interest, double-stranded RNA (dsRNA) to achieve RNA interference, use of clustered regularly interspaced short palindromic repeats (CRISPR) in concert with CRISPR-associated protein 9 (Cas9) reagents for genomic modification, and transposable elements to generate transient or stable transgenic lines.

Crickets readily lay eggs in the moist material, and providing adequate material, such as moist sand or dirt, induces them to lay a large number of eggs. This is especially effective if crickets are first deprived of egg-laying material for 8&#8211;10 h. Eggs laid in clean sand can be easily separated, collected (Figure 1B) and placed into custom-designed egg wells for injection (Figure 1C). A dissecting microscope, a microinject...

Watch this Scientific Journal Video about Injecting Gryllus bimaculatus Eggs at JoVE.com

Injecting Gryllus bimaculatus Eggs

Here we present a protocol to inject cricket eggs, a technique which serves as a foundational method in many experiments in the cricket, including, but not limited to, RNA interference and genomic manipulation.

Injecting Gryllus bimaculatus Eggs

Altering gene function in a developing organism is central to different kinds of experiments. While tremendously powerful genetic tools have been ...

This technique serves as a foundational method for experiments designed to assay the embryonic or larval development of the cricket. The main advantage of this technique is that it is flexible and will support several types of experimental approaches, such as those utilizing RNA interference or genomic manipulation. Demonstrating the procedure will be Hadley Wilson Horch, the principal investigator in the laboratory.To begin this procedure wet the spinning grinder plane of the beveler with dripping water. Place the pulled needle into the beveler and turn it to a 20 degree angle. Lower the needle until it just touches the grinding plate and bevel it for two to three minutes.Assess the bevel by placing the beveled needle on double stick tape that has been adhered to a glass microscope slide. Place the slide on the stage of a compound microscope equipped with a camera and image acquisition software. Acquire an image of the needle using a 20x objective.Use the imaging software to measure the interior lumen diameter of the needle just proximal to the beveled opening. Discard any needles with an opening smaller than eight micrometers or larger than 12 micrometers. First, make 40 milliliters of 1%agarose in water and pour it into a 10 centimeter Petri dish.Place an egg well stamp on the surface of the agarose before it solidifies. Once the agarose is solidified, remove the stamp to reveal the wells. Next, fill the agarose well plate with HBS containing 1%penicillin streptomycin.Place the lid on the dish, wrap it in Parafilm and store it at four degrees Celsius. After this, fill a 35 millimeter Petri dish with white playground sand to make an egg collection dish for the crickets to lay eggs in. Cover the egg dish with a paper towel square cut to approximately 18 by 18 centimeters.Fill with tap water through the paper towel. Then, tilt the Petri dish and gently squeeze the top to remove excess water. Tuck the corners of the paper towel square under the dish and place the egg dish in an inverted lid which will help keep the paper towel in place.Place the egg dish into the cricket bin and allow the adult females to oviposit the eggs for one to two hours. Meanwhile, allow the agarose dish to warm to room temperature in preparation for holding the eggs for injection. When ready, remove the egg collection dish, now containing freshly laid eggs, from the cricket bin.Remove the paper towel and place a strainer with a pore size between 0.5 and one millimeters over a beaker. Rinse the contents of the egg laying dish into the strainer under gently running tap water. The sand grains will fall through the strainer mesh into the beaker below while the cricket eggs remain in the strainer basket.Fill a container with reverse osmosis water and place it in a tray. Invert the strainer over the container and tap it against the dish to dislodge the eggs into the water. The eggs will sink to the bottom of the container.Next, use scissors to cut the tip off a P1000 pipette tip to make an opening approximately three millimeters in diameter. Place this tip on a P1000 pipetter, and use it to transfer the eggs from the container to the agarose egg molds dish. Using plastic tweezers, line up the eggs in the agarose wells.Each egg will sink to the bottom of an individual well. Cover the Petri dish with a lid until ready to inject. To begin, place the dish of eggs under the dissecting microscope and select a low magnification of around 10x.Draw up 1.5 microliters of injection solution using 20 microliter loading tips and a P10 pipette and insert the loading tip into the wide end of the injection needle. Expel the injection solution into the injection needle. Insert the needle into the injection housing and tighten, making sure that the needle is properly and firmly inserted into the housing.Then carefully insert the injection housing into the micromanipulator, being careful to not break or be injured by the needle. While looking at both the eggs and needle through the microscope, move the needle near the X in the top left corner of the dish grid. Lower the needle until the tip enters the HBS plus penicillin streptomycin buffered solution in the dish.Center the needle in the field of vision and move the egg dish so that the needle is a few millimeters closer to the edge of the dish than the eggs. After this, set the microscope to the filter appropriate for Rhodamine to observe the fluorescence in the needle and focus on its tip. On the microinjector slowly turn the balance knob clockwise until the injection solution starts to leak out of the needle into the suspension solution.Then turn the knob back counterclockwise slightly until the dye just stops leaking out of the needle. With the needle still centered in the field of view, move the egg dish so that the needle is aimed at the egg to be injected first. Adjust the magnification to about 50x so that a single egg fills most of the field of view.Use both the micromanipulator and one's hand on the egg dish to move the needle into position for the injection. Use the micromanipulator to advance the needle and insert the tip into the first egg to be injected, making sure to insert the needle at 20 to 30%of the egg length from the posterior end of the egg perpendicular to the long axis of the egg. Inject the solution with either the injection foot pedal or the injection button on the microinjector.A small bolus of fluorescent material inside the egg will indicate a successful injection. After this, retract the needle from the egg. If the egg is unintentionally lifted out of its well upon retraction of the needle, use small forceps to push the egg back into the well while retracting the needle.In this study, cricket eggs are injected using a technique that serves as a foundational method in many experiments, including but not limited to, RNA interference and genomic manipulation. The survival rate is one important parameter for assessing the success of this experiment. Most dead eggs can easily be identified by sight as the yolk and embryonic tissue within the egg begin to clump unevenly, and eventually most of the yolk will migrate to one side of the egg.When assessed after four to six days, greater than 85%of uninjected eggs survived, while eggs injected with experimental reagents generally had a lower survival rate. Controlling for all aspects of the injection itself, including the needle puncture, the introduction of dye and buffer, or the presence of vehicle or double stranded RNA, is required in order to understand the true effects of the experimental manipulation attempted. The way one assesses the phenotypic results of injection depends on what was injected.For example, phenotypic changes as a result of specific mRNA knockdowns may be obvious at the gross anatomy level. If on the other hand a cDNA encoding an EGFP tagged histone 2B gene under the control of a G.bimaculatus actin promoter is inserted into the cricket genome using piggyback transposase, it becomes possible to visualize each nucleus in the egg using fluorescence to excite the EGFP tagged hist 2B protein. Adjusting the balance so that the needles don't clog is a critical step in this procedure.You may need to make several adjustments after subsequent injections since yolk sometimes clogs the needle tip. The cricket is a hemimetabolous insect that branches basally to well studied holometabolous insects such as Drosophila. Studying cricket development will help us understand more about evolution and development across the animal kingdom.This technique takes some practice. We recommend practicing control injections until the survival rate four or five days after injection is at least 80%

Research

JoVE Journal

Developmental Biology

15.8K ビュー.  Colby College. この技術は、クリケットの胚または幼虫の発達をアッセイするように設計された実験の基礎的な方法として機能する。この技術の主な利点は、柔軟性があり、RNA干渉やゲノム操作を利用するものなど、いくつかのタイプの実験的アプローチをサポートすることです。手順のデモンストレーションは、研究室の主任研究者であるハドリー・ウィルソン・ホーチです。?...