Name: microinjection of western corn rootworm, diabrotica virgifera virgifera, embryos for germline transformation, or crispr/cas9 genome editing
Uploaded: 2018-04-27T14:30:00
Description: Watch this Scientific Journal Video about Microinjection of Western Corn Rootworm, Diabrotica virgifera virgifera, Embryos for Germline Transformation, or CRISPR/Cas9 Genome Editing at JoVE.com

This work was supported by a grant from the Monsanto Corn Rootworm Knowledge Research Program, grant number AG/1005 (to MDL and YC) and start-up funds to MDL from NCSU. FC was supported by grants from Monsanto&#39;s Corn Rootworm Knowledge Research Program (AG/1005) and the National Science Foundation, grant number MCB-1244772 (to MDL). The authors declare no competing interests. FC and MDL conceived and designed the experiments; FC, PW and SP performed the experiments; FC and MDL analyzed the results; and FC, NG and MDL wrote the manuscript. We thank Teresa O&#39;Leary, William Klobasa, and Stephanie Gorski for their expert assistance in screening WCR. We also thank Dr. Wade French (USDA-ARS, North Central Agricultural Research Laboratory, Brookings, SD) for shipments of eggs to establish lab colonies and providing rearing protocols.

1. Colony-level Rearing of WCR Adults
<ol>
	<li>Obtain a sufficient quantity of WCR adults (500 - 1,000) from a reliable company or research laboratory (see Table of Materials for an example) and place in a 30 cm3 cage. 
	NOTE: Use of a non-diapausing strain is highly recommended.</li>
	<li>Prepare WCR artificial diet following manufacturer&#39;s protocol and pour a 1 cm-thick layer into a 38 oz container (see Table of Materials). After mixing, store unused diet at 4 &#...

<ol>
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Although microinjection of WCR with dsRNAs for the purpose of RNAi has been reported9, this is the first protocol to establish best practices for microinjecting precellular WCR embryos, a critical process for conducting germline transformation and/or CRISPR/Cas9 genome editing in this species. Successful microinjection of WCR embryos is dependent on many factors, as is transformation efficiency. Discussed below are some of the major issues impacting the outcome of using this protocol for germline ...

Western corn rootworm (WCR), Diabrotica virgifera virgifera, is an important pest of corn1. Interestingly, WCR appears to overcome control measures more rapidly than most agricultural pests since they not only adapt physiologically but also behaviorally2,3,4,5,6. Over the past decade, RNA interference (RNAi), a powerful functional genomic tool, has been investigated as a potential control method for WCR7,8, and has also been used as a means to study gene function9. However, while RNAi is frequently performed by microinjection of double-stranded RNA (dsRNA) in other species, injection-based RNAi is rare in WCR. In fact, there are only a few reports of RNAi via microinjection of dsRNA into WCR9. The reason is that WCR can attain high-levels of gene knockdown via ingestion of dsRNA7,10, even permitting the study of embryonic effects by feeding dsRNA to the mother11. While this method makes WCR an excellent subject for functional genomic analysis via RNAi, it has slowed progress on the development of methodologies for embryonic microinjection in this species.
Despite the power of RNAi, there are a few drawbacks. For example, not all genes respond equally to RNAi. This variability can make interpreting the results of a functional genomics assay more difficult. Also, RNAi is transient and does not generate heritable mutations. On the other hand, germline transformation, another functional genomic tool, can generate heritable mutations via insertion of a marked transposable element into the genome12,13. This makes germline transformation an excellent tool for creating mutant strains for use in long-term genetic studies. Transformation can also be used to rescue a mutation by delivering a functional copy of the gene to a mutant genome14. Moreover, germline transformation is the cornerstone of a wide variety of molecular genetic techniques. In addition to knocking out and/or rescuing gene function, germline transformation can be used for enhancer trapping15, gene trapping16, Gal4-based ectopic expression17, and genome-wide mutagenesis18.
More recently, tools that enable sophisticated genome editing&#160;have been developed. These tools include Transcription Activator-Like Effector Nucleases (TALEN) and the CRISPR/Cas9-nuclease system19,20. The advantage of these new tools is that they offer researchers the ability to induce a double-stranded DNA break at almost any location within almost any genome. Once induced, these breaks can be repaired through either non-homologous end joining, which can introduce deletions or insertions in the targeted gene, or through homology-directed repair, which in the presence of an engineered construct, can catalyze the replacement of entire genes or genetic regions21,22. However, these methods require microinjection of DNA, RNA and/or protein into very young embryos.
Importantly, unlike the dsRNAs used for RNAi, the nucleic acids and proteins used for germline transformation and genome editing cannot easily cross cell membranes. Therefore, microinjection of plasmid DNAs, mRNAs, and/or proteins must take place during the syncytial blastoderm stage (i.e. before the insect embryo cellularizes). This makes the timing of injections a critical factor. For example, in Drosophila melanogaster, embryos need to be injected within two hours after egg lay12. Therefore, development of a successful embryonic microinjection protocol for WCR must take into account the best conditions for female egg laying, as well as the best method for collecting sufficient quantities of precellular embryos.
An effort to bring a wide range of molecular genetic tools to bear on WCR biology requires developing methods for collecting and microinjecting precellular WCR embryos. Here we provide detailed instructions, along with tips and tricks, to help others use transformation-based techniques in WCR research. In addition to extending transgenic technologies to WCR for use in functional genomic studies, these techniques also enable powerful new pest control strategies such as gene drive23,24 to be tested in this economically important pest.

<table border="0" cellpadding="0" cellspacing="0" width="1155">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Qualitative Filter Paper (Black)</td>
			<td style="width:189px;">Ahlstrom</td>
			<td style="width:287px;">8613-0900</td>
			<td style="width:339px;">For egg microinjection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1 oz Containers&#160;</td>
			<td style="width:189px;">Anny&#39;s Plastic Tableware</td>
			<td>ASET101</td>
			<td>Egg container</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Drosophila Agar Type II</td>
			<td style="width:189px;">Apex</td>
			<td style="width:287px;">66-103</td>
			<td>Substrate for WCR egg-laying dish</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Featherweight Forceps&#160;</td>
			<td>Bioquip</td>
			<td style="width:287px;">4748</td>
			<td>Handling larvae and pupae&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Clorox Regular-Bleach1</td>
			<td style="width:189px;">Clorox</td>
			<td style="width:287px;">44600-30770</td>
			<td>Wash corn and dishes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trucker&#39;s Favorite Yellow</td>
			<td>Coor Farm Supply</td>
			<td>502</td>
			<td>Corn for feeding WCR</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Microinjection System (Homemade)</td>
			<td style="width:189px;">NA</td>
			<td style="width:287px;">Parts &#38; instructions available upon request</td>
			<td>Controls injection pressure (0-20 psi)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Elmer&#39;s Non-toxic Glue</td>
			<td>Elmer&#39;s Products, Inc.</td>
			<td style="width:287px;">E304</td>
			<td>Glue eggs on filter paper</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">epTIPS Microloader Tips</td>
			<td style="width:189px;">Eppendorf</td>
			<td style="width:287px;">C2554691</td>
			<td>Backfilling needle loading tips</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Falcon Tissue Culture Dishes</td>
			<td style="width:189px;">Falcon</td>
			<td>25383-103</td>
			<td>Sprouting corn /150 x 25 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fisherbrand&#160;Quantitative-Grade Filter Paper Circles</td>
			<td style="width:189px;">Fisher Scientific</td>
			<td>S47576C</td>
			<td>Making agar dish for egg-lay/9cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Sparkleen</td>
			<td style="width:189px;">Fisher Scientific</td>
			<td style="width:287px;">04-320-4</td>
			<td>Wash dishes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Plain Microscope Slides</td>
			<td style="width:189px;">Fisher Scientific</td>
			<td style="width:287px;">12-549-3</td>
			<td>Holding filter paper and eggs for microinjection</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Western Corn Rootworm w/o Pollen Substitute</td>
			<td style="width:189px;">Frontier Agricultural Sciences&#160;</td>
			<td>F9766B</td>
			<td>WCR adult artificial diet</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cotton Balls, Large</td>
			<td>Genesee Scientific</td>
			<td>51-101</td>
			<td>Close the flask</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Globe Scientific 3.0 mL Small Bulb Transfer Pipettes</td>
			<td>Globe Scientific</td>
			<td>137035</td>
			<td>Collect and transfer eggs</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Leica M165 FC Fluorescence Stereomicroscope&#160;</td>
			<td style="width:189px;">Leica</td>
			<td>M165 FC&#160;</td>
			<td>WCR screening</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DsRed Filter Set for Fluorescence Stereomicroscope</td>
			<td style="width:189px;">Leica</td>
			<td>DSR</td>
			<td>Excitation filter: 510-560 nm, emission filter: 590-650 nm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EGFP filter</td>
			<td style="width:189px;">Leica</td>
			<td>GFP2</td>
			<td>Excitation filter: 440&#8211;520 nm, emission filter: 510 nm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BugDorm</td>
			<td>MegaView Science</td>
			<td>DP1000_5P</td>
			<td>Cage for adult colony</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Miniature Paint Brush</td>
			<td style="width:189px;">MyArtscape</td>
			<td>MAS-102-MINI</td>
			<td>Liner 2/0&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Joystick Micromanipulator</td>
			<td style="width:189px;">Narishige</td>
			<td style="width:287px;">MN-151</td>
			<td>Micromanipulator and needle holder</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:343px;">Microscope XY Stage</td>
			<td style="width:189px;">Olympus</td>
			<td style="width:287px;">265515</td>
			<td style="width:339px;">Microscope stage (adapted for use with stereoscope)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Grade 90 Cheesecloth</td>
			<td style="width:189px;">Online Fabric Store</td>
			<td>CHEE90</td>
			<td>For egg-lay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Plastic paraffin film&#160;</td>
			<td style="width:189px;">Pechiney Plastic Packaging</td>
			<td>PM-996</td>
			<td>Seal agar dish after microinjection/Roll size 4 in. x 125 ft</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Percival Incubator</td>
			<td style="width:189px;">Percival&#160;</td>
			<td style="width:287px;">I41VLH3C8</td>
			<td>WCR growing chamber (insect rearing incubator)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Narrow Mouth Erlenmeyer Flasks</td>
			<td style="width:189px;">VWR</td>
			<td>4980-300-PK</td>
			<td>Water container for adult colony&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Griffin Low Form Beakers</td>
			<td style="width:189px;">VWR</td>
			<td>1000-600-PK</td>
			<td>For egg wash</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Braided Cotton Rolls</td>
			<td>Richmond Dental Cotton Co.</td>
			<td>605-3599</td>
			<td>Use in water supply for adult colony&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Petri Dishes (35x10mm)</td>
			<td>SIGMA</td>
			<td>CLS430588-500EA</td>
			<td>For diet plates</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phenol Red</td>
			<td>Sigma</td>
			<td style="width:287px;">143-78-8</td>
			<td>Microinjection buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Laser-based Micropipiette Puller</td>
			<td>Sutter Instrument</td>
			<td>P-2000/G</td>
			<td>Needle puller/Heat = 335, FIL = 4, VEL = 40, DEL = 200, PUL = 100</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Premium Topsoil</td>
			<td>The Scotts Company</td>
			<td style="width:287px;">71130758</td>
			<td>Soil for cron growing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Reloc Zippit 2 Mil Zipper Bags</td>
			<td>United States Plastic Corporation</td>
			<td>48342</td>
			<td>Bag agar dish after microinjection/5x7</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Petri Dishes (100x15m)</td>
			<td style="width:189px;">VWR</td>
			<td style="width:287px;">89038-968</td>
			<td>Making agar dish for egg-lay/ 100 x 15 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">6 oz Containers</td>
			<td style="width:189px;">Webstaurantstore</td>
			<td>128E506</td>
			<td>WCR single pair mating chamber&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">38 oz Containers</td>
			<td style="width:189px;">Webstaurantstore</td>
			<td>128NC888</td>
			<td>Larvae rearing box/38 oz</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ChoiceHD 16 oz. Microwavable Translucent Plastic Deli Container</td>
			<td style="width:189px;">Webstaurantstore</td>
			<td>128HRD16</td>
			<td>Larvae rearing box/16 oz</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Microinjection Scope&#160;</td>
			<td style="width:189px;">Wild Heerbrugg</td>
			<td style="width:287px;">WILD-M8</td>
			<td style="width:339px;">Microinjection scope outfited with an XY stage</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Standard Glass Capillaries</td>
			<td>World Precision Instruments</td>
			<td>1B100F-4</td>
			<td>Microinjection needles</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:343px;">Adult Western Corn Rootworms</td>
			<td style="width:189px;">North Centeral Aqricultural reasearch Laboratory</td>
			<td style="width:287px;">Non-diapase strain</td>
			<td>Request from Dr. Bryan Wade French&#39;s lab</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Plasmid DNA Midi Kit</td>
			<td style="width:189px;">Qiagen</td>
			<td>12143</td>
			<td>Purification of injection-ready plasmid DNAs</td>
		</tr>
	</tbody>
</table>

microinjection of western corn rootworm, diabrotica virgifera virgifera, embryos for germline transformation, or crispr/cas9 genome editing

The western corn rootworm (WCR) is an important pest of corn and is well known for its ability to rapidly adapt to pest management strategies. Although RNA interference (RNAi) has proved to be a powerful tool for studying WCR biology, it has its limitations. Specifically, RNAi itself is transient (i.e. does not result in long-term Mendelian inheritance of the associated phenotype), and it requires knowing the DNA sequence of the target gene. The latter can be limiting if the phenotype of interest is controlled by poorly conserved, or even novel genes, because identifying useful targets would be challenging, if not impossible. Therefore, the number of tools in WCR&#39;s genomic toolbox should be expanded by the development of methods that could be used to create stable mutant strains and enable sequence-independent surveys of the WCR genome. Herein, we detail the methods used to collect and microinject precellular WCR embryos with nucleic acids. While the protocols described herein are aimed at the creation of transgenic WCR, CRISPR/Cas9-genome editing could also be performed using the same protocols, with the only difference being the composition of the solution injected into the embryos.

An important consideration when developing this protocol was the stage of embryonic development at the time of microinjection. Specifically, germline transformation requires microinjection of DNAs prior to embryonic cellularization. This is because DNAs cannot easily cross cell membranes. Attempts to visualize the stages of WCR embryonic development using a nuclear stain were unsuccessful because dechorionation of WCR embryos essentially dissolves all of the protective membranes responsib...

Watch this Scientific Journal Video about Microinjection of Western Corn Rootworm, Diabrotica virgifera virgifera, Embryos for Germline Transformation, or CRISPR/Cas9 Genome Editing at JoVE.com

Microinjection of Western Corn Rootworm, Diabrotica virgifera virgifera, Embryos for Germline Transformation, or CRISPR/Cas9 Genome Editing

Here we present protocols for collecting and microinjecting precellular western corn rootworm embryos for the purpose of performing functional-genomic assays such as germline transformation and CRISPR/Cas9-genome editing.

Microinjection of Western Corn Rootworm, Diabrotica virgifera virgifera, Embryos for Germline Transformation, or CRISPR/Cas9 Genome Editing

The western corn rootworm (WCR) is an important pest of corn and is well known for its ability to rapidly adapt to pest management strategies. Although ...

The overall goal of this Microinjection protocol is to modify the Western Corn Rootworm genome. This method can help answer key questions regarding Western Corn Rootworm biology and their ability to quickly overcome pest control methods such as BT Toxin and RANI. Besides Western Corn Rootworms, this method can also be applied to similar species, such as Southern and Northern Rootworms.I first had the idea for this method when I was asked to help with injection based RANI in Western Corn Rootworm back in the 90's. Generally, individuals new to this method will struggle. Because rearing Western Corn Rootworms in the laboratory is labor intensive.And survival rates remain low using current technology. Obtain between 500 and 1, 000 non-diapausing rootworm adults from a reliable company or research laboratory. And house them at 30 cubic centimeter cages.Store the standard rootworm artificial diet in food storage containers about one centimeter deep. Unused diet can be stored at four degrees Celsius for up to two months. To feed the rootworm, load 100 centimeter Petri dishes with 10 to 15 grams of diet.Load one dish of food into each rootworm cage. And replenish it when the supply runs low or the diet dries out. Also keep a 300 milliliter water reservoir, covered by a cotton ball, in each cage to serve as a water source.Change the water when it runs low. Maintain the caged rootworm at 26 degrees Celsius with 60%humidity and a 14/10 light cycle in an insect rearing incubator. Set the lights off time later in the day such as at midnight so eggs are laid before morning work hours.First, collect the embryos. For an egg collection surface, load a 100 millimeter Petri dish with 30 milliliters of 1%agar and water. Next, place a single layer of filter paper on the agar, followed by four layers of cheese cloth.Each layer should be cut to size. Next, as late in the day as possible, place the egg collection plate into the rootworm cage and cover it with a tinfoil tent. Then on the following morning, remove the egg collection chamber.Use forceps to pick up one layer of cheese cloth at a time and place into 500 milliliter beaker loaded with water. Wash the eggs off of the cheese cloth by swirling in the water. Then, use a bulb pipet to transfer the eggs to another beaker of water as a wash step.Perform two or three washes in this manner. Then, deposit the cleaned eggs onto filter paper with as little water as possible. Next, prepare a slide by taping a piece of black filter paper flat to the slide to improve contrast.Then drizzle fine lines of non-toxic glue onto the paper that will be used to secure the eggs. Keep the glue below the girth of an egg. While the glue is wet, use a fine brush to place the eggs onto the glue line.Keep at least one egg's distance between each egg. Prepare multiple lines of eggs per slide. The eggs should now be injected within 30 minutes.Now, combine the helper plasmid, donor plasmid, and phenol red buffer. Use high quality, super coiled plasmids made with an endotoxin-free commercial kit. Fortex briefly to mix.And then spin down particulates for three minutes at maximum speed. Next, backfill pulled borosilicate glass needles with 0.5 to 1 microliters of injection solution. If any bubbles form, be sure to remove them.Then, attach the injection needle to the micromanipulator. Now, if necessary, under the microscope, gently break off the sealed needle tip using a fine pair of forceps or by gently touching the tip into a glass barrier. Try to make the smallest possible opening that releases injection solution.Before injecting the rootworm eggs, use a fine paintbrush to carefully wet the surface of one to three prepared eggs with sterile water. Then, inject the wetted embryos. Gently insert the needle into the middle of the embryo, and inject a small volume of solution.Start with using 10 to 13 psi of pressure and adjust the pressure as needed. Dry embryos has a distinct round shape, by pre-wetting each embryo with water will change their shape and soften the eggshell thus allowing the needle to easily penetrate. A successfully injected embryo will have a small amount of red color.If an egg was damaged, looks peculiar, or cannot be injected then crush it or remove it from the slide. After all eggs are injected, move the filter paper with the eggs on it to a 1%agar dish. Then, seal the dish with paraffin film and incubate it at 26 degrees Celsius until larvae hatch.12 days after injection, start checking for larvae everyday for the next two weeks. Transfer the larvae using a fine brush to a rearing box with sprouted corn and soil to rear them under standard conditions. Germline transformation of rootworm was attempted by co-injecting a transposase carrying plasmid with a transposon carrying plasmid into pre-cellular embryos.In the 26 survivors, each EFP expression was used to screen for donor element insertion. Although thoracent progeny were identified, screening rootworm embryos with the intense light source proved to be lethal. The next round of germline transformation utilized a red florescent protein gene driven by a constitutively active promoter from Drosophila melanogaster.Survival rates improved, but only one DS red positive larvae was recorded. Next, embryos were micro-injected with buffer alone or with helper and thorescently marked donor DNA plasmids. A similar ratio of embryos hatched when injected with plasmids or buffer alone.And interestingly, only about half of un-injected embryos hatched. This put the lethality of manipulating the embryos for the injection as high as performing the injection. After watching this video, you should have a good understanding of how to micro inject Western Corn Rootwall embryos.Once mastered two to three hundred embryos can be injected per hour using this technique. This method is indebted to techniques developed for germline transformation of Drosophila melanogaster which serve as templates applicable to many other species. Following this procedure, other methods like CRISPR/Cas9 based genome editing can be performed to make targeted mutations in Western Corn Rootwall's genome.In order to answer specific questions about genome function.

microinjection-western-corn-rootworm-diabrotica-virgifera-virgifera

Research

JoVE Journal

Bioengineering

Viral Nanoparticles for In vivo Tumor Imaging

The use of nanomaterials has the potential to revolutionize materials science and medicine. Currently, a number of different nanoparticles are being investigated for applications in imaging and therapy. Viral nanoparticles (VNPs) derived from plants can be regarded as self-assembled bionanomaterials with defined sizes and shapes. Plant viruses under investigation in the Steinmetz lab include icosahedral particles formed by Cowpea mosaic virus (CPMV) and Brome mosaic virus (BMV), both of which are 30 nm in diameter. We are also developing rod-shaped and filamentous structures derived from the following plant viruses: Tobacco mosaic virus (TMV), which forms rigid rods with dimensions of 300 nm by 18 nm, and Potato virus X (PVX), which form filamentous particles 515 nm in length and 13 nm in width (the reader is referred to refs. 1 and 2 for further information on VNPs).
From a materials scientist's point of view, VNPs are attractive building blocks for several reasons: the particles are monodisperse, can be produced with ease on large scale in planta, are exceptionally stable, and biocompatible. Also, VNPs are "programmable" units, which can be specifically engineered using genetic modification or chemical bioconjugation methods 3. The structure of VNPs is known to atomic resolution, and modifications can be carried out with spatial precision at the atomic level4, a level of control that cannot be achieved using synthetic nanomaterials with current state-of-the-art technologies.
In this paper, we describe the propagation of CPMV, PVX, TMV, and BMV in Vigna ungiuculata and Nicotiana benthamiana plants. Extraction and purification protocols for each VNP are given. Methods for characterization of purified and chemically-labeled VNPs are described. In this study, we focus on chemical labeling of VNPs with fluorophores (e.g. Alexa Fluor 647) and polyethylene glycol (PEG). The dyes facilitate tracking and detection of the VNPs 5-10, and PEG reduces immunogenicity of the proteinaceous nanoparticles while enhancing their pharmacokinetics 8,11. We demonstrate tumor homing of PEGylated VNPs using a mouse xenograft tumor model. A combination of fluorescence imaging of tissues ex vivo using Maestro Imaging System, fluorescence quantification in homogenized tissues, and confocal microscopy is used to study biodistribution. VNPs are cleared via the reticuloendothelial system (RES); tumor homing is achieved passively via the enhanced permeability and retention (EPR) effect12. The VNP nanotechnology is a powerful plug-and-play technology to image and treat sites of disease in vivo. We are further developing VNPs to carry drug cargos and clinically-relevant imaging moieties, as well as tissue-specific ligands to target molecular receptors overexpressed in cancer and cardiovascular disease.

Viral Nanoparticles for In vivo Tumor Imaging

Plant viral nanoparticles (VNPs) are promising platforms for applications in biomedicine. Here, we describe the procedures for plant VNP propagation, purification, characterization, and bioconjugation. Finally, we show the application of VNPs for tumor homing and imaging using a mouse xenograft model and fluorescence imaging.

The use of nanomaterials has the potential to revolutionize materials science and medicine. Currently, a number of different nanoparticles are being ...

Microinjection Wound Assay and In vivo Localization of Epidermal Wound Response Reporters in Drosophila Embryos.

The Drosophila embryo develops a robust epidermal layer that serves both to protect the internal cells from a harsh external environment as well as to maintain cellular homeostasis. Puncture injury with glass needles provides a direct method to trigger a rapid epidermal wound response that activates wound transcriptional reporters, which can be visualized by a localized reporter signal in living embryos or larvae. Puncture or laser injury also provides signals that promote the recruitment of hemocytes to the wound site. Surprisingly, severe (through and through) puncture injury in late stage embryos only rarely disrupts normal embryonic development, as greater than 90% of such wounded embryos survive to adulthood when embryos are injected in an oil medium that minimizes immediate leakage of hemolymph from puncture sites. The wound procedure does require micromanipulation of the Drosophila embryos, including manual alignment of the embryos on agar plates and transfer of the aligned embryos to microscope slides. The Drosophila epidermal wound response assay provides a quick system to test the genetic requirements of a variety of biological functions that promote wound healing, as well as a way to screen for potential chemical compounds that promote wound healing. The short life cycle and easy culturing routine make Drosophila a powerful model organism. Drosophila clean wound healing appears to coordinate the epidermal regenerative response, with the innate immune response, in ways that are still under investigation, which provides an excellent system to find conserved regulatory mechanisms common to Drosophila and mammalian epidermal wounding.

Microinjection Wound Assay and In vivo Localization of Epidermal Wound Response Reporters in Drosophila Embryos.

The embryonic epidermis of very late stage Drosophila embryos provides an in vivo system for rapid puncture wound response analysis and can be combined with genetic manipulations or chemical microinjection treatments to advance studies in wound healing for translation into mammalian models.

The Drosophila embryo develops a robust epidermal layer that serves both to protect the internal cells from a harsh external environment as well as to ...

Efficient Generation and Editing of Feeder-free IPSCs from Human Pancreatic Cells Using the CRISPR-Cas9 System

Embryonic and induced pluripotent stem cells can self-renew and differentiate into multiple cell types of the body. The pluripotent cells are thus coveted for research in regenerative medicine and are currently in clinical trials for eye diseases, diabetes, heart diseases, and other disorders. The potential to differentiate into specialized cell types coupled with the recent advances in genome editing technologies including the CRISPR/Cas system have provided additional opportunities for tailoring the genome of iPSC for varied applications including disease modeling, gene therapy, and biasing pathways of differentiation, to name a few. Among the available editing technologies, the CRISPR/Cas9 from Streptococcus pyogenes has emerged as a tool of choice for site-specific editing of the eukaryotic genome. The CRISPRs are easily accessible, inexpensive, and highly efficient in engineering targeted edits. The system requires a Cas9 nuclease and a guide sequence (20-mer) specific to the genomic target abutting a 3-nucleotide &#34;NGG&#34; protospacer-adjacent-motif (PAM) for targeting Cas9 to the desired genomic locus, alongside a universal Cas9 binding tracer RNA (together called single guide RNA or sgRNA). Here we present a step-by-step protocol for efficient generation of feeder-independent and footprint-free iPSC and describe methodologies for genome editing of iPSC using the Cas9 ribonucleoprotein (RNP) complexes. The genome editing protocol is effective and can be easily multiplexed by pre-complexing sgRNAs for more than one target with the Cas9 protein and simultaneously delivering into the cells. Finally, we describe a simplified approach for identification and characterization of iPSCs with desired edits. Taken together, the outlined strategies are expected to streamline generation and editing of iPSC for manifold applications.

This protocol describes in detail the generation of footprint-free induced pluripotent stem cells (iPSCs) from human pancreatic cells in feeder-free conditions, followed by editing using CRISPR/Cas9 ribonucleoproteins and characterization of the modified single-cell clones.

Embryonic and induced pluripotent stem cells can self-renew and differentiate into multiple cell types of the body. The pluripotent cells are thus coveted ...

Production of Genetically Engineered Golden Syrian Hamsters by Pronuclear Injection of the CRISPR/Cas9 Complex

The pronuclear (PN) injection technique was first established in mice to introduce foreign genetic materials into the pronuclei of one-cell stage embryos. The introduced genetic material may integrate into the embryonic genome and generate transgenic animals with foreign genetic information following transfer of the injected embryos to foster mothers. Following the success in mice, PN injection has been applied successfully in many other animal species. Recently, PN injection has been successfully employed to introduce reagents with gene-modifying activities, such as the CRISPR/Cas9 system, to achieve site-specific genetic modifications in several laboratory and farm animal species. In addition to mastering the special set of microinjection skills to produce genetically modified animals by PN injection, researchers must understand the reproduction physiology and behavior of the target species, because each species presents unique challenges. For example, golden Syrian hamster embryos have unique handling requirements in vitro such that PN injection techniques were not possible in this species until recent breakthroughs by our group. With our species-modified PN injection protocol, we have succeeded in producing several gene knockout (KO) and knockin (KI) hamsters, which have been used successfully to model human diseases. Here we describe the PN injection procedure for delivering the CRISPR/Cas9 complex to the zygotes of the hamster, the embryo handling conditions, embryo transfer procedures, and husbandry required to produce genetically modified hamsters.

Pronuclear (PN) injection of the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein-9 nuclease (CRISPR/Cas9) system is a highly efficient method for producing genetically engineered golden Syrian hamsters. Herein, we describe the detailed PN injection protocol for the production of gene knockout hamsters with the CRISPR/Cas9 system.

The pronuclear (PN) injection technique was first established in mice to introduce foreign genetic materials into the pronuclei of one-cell stage embryos. ...

Ultra-long Read Sequencing for Whole Genomic DNA Analysis

Third generation single-molecule DNA sequencing technologies offer significantly longer read length that can facilitate the assembly of complex genomes and analysis of complex structural variants. Nanopore platforms perform single-molecule sequencing by directly measuring the current changes mediated by DNA passage through the pores and can generate hundreds of kilobase (kb) reads with minimal capital cost. This platform has been adopted by many researchers for a variety of applications. Achieving longer sequencing read lengths is the most critical factor to leverage the value of nanopore sequencing platforms. To generate ultra-long reads, special consideration is required to avoid DNA breakages and gain efficiency to generate productive sequencing templates. Here, we provide the detailed protocol of ultra-long DNA sequencing including high molecular weight (HMW) DNA extraction from fresh or frozen cells, library construction by mechanical shearing or transposase fragmentation, and sequencing on a nanopore device. From 20-25 &#181;g of HMW DNA, the method can achieve N50 read length of 50-70 kb with mechanical shearing and N50 of 90-100 kb read length with transposase mediated fragmentation. The protocol can be applied to DNA extracted from mammalian cells to perform whole genome sequencing for the detection of structural variants and genome assembly. Additional improvements on the DNA extraction and enzymatic reactions will further increase the read length and expand its utility.

Long-read sequences greatly facilitate the assembly of complex genomes and characterization of structural variation. We describe a method to generate ultra-long sequences by nanopore-based sequencing platforms. The approach adopts an optimized DNA extraction followed by modified library preparations to generate hundreds of kilobase reads with moderate coverage from human cells.

Third generation single-molecule DNA sequencing technologies offer significantly longer read length that can facilitate the assembly of complex genomes ...

CRISPR/Cas12a Multiplex Genome Editing of Saccharomyces cerevisiae and the Creation of Yeast Pixel Art

High efficiency, ease of use and versatility of the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system has facilitated advanced genetic modification of Saccharomyces cerevisiae, a model organism and workhorse in industrial biotechnology. CRISPR-associated protein 12a (Cas12a), an RNA-guided endonuclease with features distinguishable from Cas9 is applied in this work, further extending the molecular toolbox for genome editing purposes. A benefit of the CRISPR/Cas12a system is that it can be used in multiplex genome editing with multiple guide RNAs expressed from a single transcriptional unit (single CRISPR RNA (crRNA) array). We present a protocol for multiplex integration of multiple heterologous genes into independent loci of the S. cerevisiae genome using the CRISPR/Cas12a system with multiple crRNAs expressed from a single crRNA array construct. The proposed method exploits the ability of S. cerevisiae to perform in vivo recombination of DNA fragments to assemble the single crRNA array into a plasmid that can be used for transformant selection, as well as the assembly of donor DNA sequences that integrate into the genome at intended positions. Cas12a is pre-expressed constitutively, facilitating cleavage of the S.&#160;cerevisiae genome at the intended positions upon expression of the single crRNA array. The protocol includes the design and construction of a single crRNA array and donor DNA expression cassettes, and exploits an integration approach making use of unique 50-bp DNA connectors sequences and separate integration flank DNA sequences, which simplifies experimental design through standardization and modularization and extends the range of applications. Finally, we demonstrate a straightforward technique for creating yeast pixel art with an acoustic liquid handler using differently colored carotenoid producing yeast strains that were constructed.

CRISPR/Cas12a Multiplex Genome Editing of Saccharomyces cerevisiae and the Creation of Yeast Pixel Art

The CRISPR/Cas12a system in combination with a single crRNA array enables efficient multiplex editing of the S.&#160;cerevisiae genome at multiple loci simultaneously. This is demonstrated by constructing carotenoid producing yeast strains which are subsequently used to create yeast pixel art.

High efficiency, ease of use and versatility of the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) ...

Measuring the Spin-Lattice Relaxation Magnetic Field Dependence of Hyperpolarized [1-13C]pyruvate

The fundamental limit to in vivo imaging applications of hyperpolarized 13C-enriched compounds is their finite spin-lattice relaxation times. Various factors affect the relaxation rates, such as buffer composition, solution pH, temperature, and magnetic field. In this last regard, the spin-lattice relaxation time can be measured at clinical field strengths, but at lower fields, where these compounds are dispensed from the polarizer and transported to the MRI, the relaxation is even faster and difficult to measure. To have a better understanding of the amount of magnetization lost during transport, we used fast field-cycling relaxometry, with magnetic resonance detection of 13C nuclei at ~0.75 T, to measure the nuclear magnetic resonance dispersion of the spin-lattice relaxation time of hyperpolarized [1-13C]pyruvate. Dissolution dynamic nuclear polarization was used to produce hyperpolarized samples of pyruvate at a concentration of 80 mmol/L and physiological pH (~7.8). These solutions were rapidly transferred to a fast field-cycling relaxometer so that relaxation of the sample magnetization could be measured as a function of time using a calibrated small flip angle (3&#176;-5&#176;). To map the T1 dispersion of the C-1 of pyruvate, we recorded data for different relaxation fields ranging between 0.237 mT and 0.705 T. With this information, we determined an empirical equation to estimate the spin-lattice relaxation of the hyperpolarized substrate within the mentioned range of magnetic fields. These results can be used to predict the amount of magnetization lost during transport and to improve experimental designs to minimize signal loss.

Measuring the Spin-Lattice Relaxation Magnetic Field Dependence of Hyperpolarized [1-13C]pyruvate

We present a protocol to measure the magnetic field dependence of the spin-lattice relaxation time of 13C-enriched compounds, hyperpolarized by means of dynamic nuclear polarization, using fast field-cycled relaxometry. Specifically, we have demonstrated this with [1-13C]pyruvate, but the protocol could be extended to other hyperpolarized substrates.

The fundamental limit to in vivo imaging applications of hyperpolarized 13C-enriched compounds is their finite spin-lattice relaxation times. Various ...

Microinjection of Corn Planthopper, Peregrinus maidis, Embryos for CRISPR/Cas9 Genome Editing

The corn planthopper, Peregrinus maidis, is&#160;a pest of maize and a vector of several maize viruses. Previously published methods describe the triggering of RNA interference (RNAi) in P. maidis through microinjection of double-stranded RNAs (dsRNAs) into nymphs and adults. Despite the power of RNAi, phenotypes generated via this technique are transient and lack long-term Mendelian inheritance. Therefore, the P. maidis toolbox needs to be expanded to include functional genomic tools that would enable the production of stable mutant strains, opening the door for researchers to bring new control methods to bear on this economically important pest. However, unlike the dsRNAs used for RNAi, the components used in CRISPR/Cas9-based genome editing and germline transformation do not easily cross cell membranes. As a result, plasmid DNAs, RNAs, and/or proteins must be microinjected into embryos before the embryo cellularizes, making the timing of injection a critical factor for success. To that end, an agarose-based egg-lay method was developed to allow embryos to be harvested from P. maidis females at relatively short intervals. Herein are provided detailed protocols for collecting and microinjecting precellular P. maidis embryos with CRISPR components (Cas9 nuclease that has been complexed with guide RNAs), and results of Cas9-based gene knockout of a P. maidis eye-color gene, white, are presented. Although these protocols describe CRISPR/Cas9-genome editing in P. maidis, they can also be used for producing transgenic P. maidis via germline transformation by simply changing the composition of the injection solution.

Microinjection of Corn Planthopper, Peregrinus maidis, Embryos for CRISPR/Cas9 Genome Editing

Herein are protocols for collecting and microinjecting precellular corn planthopper embryos for the purpose of modifying their genome via CRISPR/Cas9-based genome editing or for the addition of marked transposable elements through germline transformation.

The corn planthopper, Peregrinus maidis, is&#160;a pest of maize and a vector of several maize viruses. Previously published methods describe the ...

Liquid Chromatography Coupled to Refractive Index or Mass Spectrometric Detection for Metabolite Profiling in Lysate-based Cell-free Systems

Engineering cellular metabolism for targeted biosynthesis can require extensive design-build-test-learn (DBTL) cycles as the engineer works around the cell&#39;s survival requirements. Alternatively, carrying out DBTL cycles in cell-free environments can accelerate this process and alleviate concerns with host compatibility. A promising approach to cell-free metabolic engineering (CFME) leverages metabolically active crude cell extracts as platforms for biomanufacturing and for rapidly discovering and prototyping modified proteins and pathways. Realizing these capabilities and optimizing CFME performance requires methods to characterize the metabolome of lysate-based cell-free platforms. That is, analytical tools are necessary for monitoring improvements in targeted metabolite conversions and in elucidating alterations to metabolite flux when manipulating lysate metabolism. Here, metabolite analyses using high-performance liquid chromatography (HPLC) coupled with either optical or mass spectrometric detection were applied to characterize metabolite production and flux in E. coli S30 lysates. Specifically, this report describes the preparation of samples from CFME lysates for HPLC analyses using refractive index detection (RID) to quantify the generation of central metabolic intermediates and by-products in the conversion of low-cost substrates (i.e., glucose) to various high-value products. The analysis of metabolite conversion in CFME reactions fed with 13C-labeled glucose through reversed-phase liquid chromatography coupled to tandem mass spectrometry (MS/MS), a powerful tool for characterizing specific metabolite yields and lysate metabolic flux from starting materials, is also presented. Altogether, applying these analytical methods to CFME lysate metabolism enables the advancement of these systems as alternative platforms for executing faster or novel metabolic engineering tasks.

The protocols describe high-performance liquid chromatography methods coupled to refractive index or mass spectrometric detection for studying metabolic reactions in complex lysate-based cell-free systems.

Engineering cellular metabolism for targeted biosynthesis can require extensive design-build-test-learn (DBTL) cycles as the engineer works around the ...

Microtubule Plus-End Dynamics Visualization in Huntington's Disease Model based on Human Primary Skin Fibroblasts

Transfection with a fluorescently labeled marker protein of interest in combination with time-lapse video microscopy is a classic method of studying the dynamic properties of the cytoskeleton. This protocol offers a technique for human primary fibroblast transfection, which can be difficult because of the specifics of primary cell cultivation conditions. Additionally, cytoskeleton dynamic property maintenance requires a low level of transfection to obtain a good signal-to-noise ratio without causing microtubule stabilization. It is important to take measures to protect the cells from light-induced stress and fluorescent dye fading. In the course of our work, we tested different transfection methods and protocols as well as different vectors to select the best combination of conditions suitable for human primary fibroblast studies. We analyzed the resulting time-lapse videos and calculated microtubule dynamics using ImageJ. The dynamics of microtubules' plus-ends in the different cell parts are not similar, so we divided the analysis into subgroups - the centrosome region, the lamella, and the tail of fibroblasts. Notably, this protocol can be used for in vitro analysis of cytoskeleton dynamics in patient samples, enabling the next step towards understanding the dynamics of the various disease development.

Microtubule Plus-End Dynamics Visualization in Huntington&#039;s Disease Model based on Human Primary Skin Fibroblasts

This protocol is dedicated to the microtubule plus-end visualization by EB3 protein transfection to study their dynamic properties in primary cell culture. The protocol was implemented on human primary skin fibroblasts obtained from Huntington's disease patients.

Transfection with a fluorescently labeled marker protein of interest in combination with time-lapse video microscopy is a classic method of studying the ...