Preparation in advance of microinjection:
<ol>
<li>Blood feed mosquitoes: for injection from Monday to Wednesday feed females on the previous Friday. To inject Thursday and Friday, feed females on Monday of the same week. </li>
<li>Prepare the Quartz needles using program 2 and isotonic buffer (see Materials). </li>
<li>"Laying tube" for the embryos is the regular Drosophila culture vial. Wet cotton wool in the bottom, with a wet disk of filter paper covering it. </li>
<li>Prepare plastic cover slip by sticking double-side tape to one end. Trim tape to cover slip so that it ends at edge of cover slip. </li>
<li>Prepare oil for desiccation. </li>
<li>Prepare a Petri dish with isotonic buffer to transfer embryos for hatching. </li>
</ol>
Set up of forced laying:
<ol>
<li>Collect 6-10 blood fed females with the use of an aspirator and transfer them to the Drosophila culture vial with cotton and filter paper wet with isotonic buffer. </li>
<li>The mosquitoes are then put back into insectery conditions in the dark and allowed to lay eggs for 1 h and 15 min. </li>
<li>Let adults fly into the cage and remove the filter paper disk with embryos. </li>
<li>To line up eggs, do it under the dissecting scope. Collect bunches of eggs with a fine paintbrush (Sable, No 0000) and transfer to a prepared square of 3MM Whatman paper soaked with isotonic buffer. Keep paper all time wet. Don't let eggs get desiccated. Remove the exochorion with the brush, it helps to better stick eggs to the tape. </li>
<li>Using fine forcep No. 5 or a fine paintbrush, pick up darker grey embryos and arrange in line on square of 3MM Whatman wet with isotonic buffer. Line up from 20-30 embryos. All embryos must be in the same orientation as injection has to be at posterior pole. The anterior end of the embryos is slightly wider than the posterior. Then, using stripes of 3MM Whatman paper, dry the filter where the eggs are lined up by pressing hard on both sides of the egg line, not touching the eggs. </li>
<li>To transfer the eggs, invert the slide containing the double sided tape (Medicine), and gently press against the eggs. The posterior end of the eggs have to be very close to the edge of the double sided tape. The wetness of the paper is critical for this, if it is too wet they won't stick. I do desiccation of the embryos from 5-10 second, but desiccation time depends from humid and temperature in microinjection room. </li>
<li>Desiccation is crucial for eggs: little bit too much and embryos will not hatch. Without desiccation DNA is not going into embryo. </li>
<li>Cover desiccated embryos with halocarbon oil to prevent further desiccation. </li>
</ol>
Microinjection of the embryos:
The most important aspect of good injection is the quality of the needle (see Note).
<ol>
<li>Fill a needle with the DNA solution to be injected by using a microloader (Eppendorf #5242 956.003). Very little injection soliution is needed, 1 to 2 ml. </li>
<li>Connect the needle to the Eppendorf &nbsp;Transjector, which controls the injection time and pressure, as well as the backpressure. Microinjection is performed using a microscope with a moving stage (Leica) at x 10 magnification and micromanipulator (Leica). If necessary, a raised microscope stage may be prepared by stacking 4-5 microscope slides. Place the cover slip carrying the embryos onto raised stage. Embryos are injected at a 150&deg;&nbsp;angle; penetration should be at the posterior pole. For injection, I keep the needle stationary and move the stage of the microscope. When the needle is new, the tip is sealed and usually breaks in the first injection. I always work out the pressure needed to expel a small droplet of DNA into oil in between each injection. </li>
<li>I set the injection time to 0.2 - 0.9 sec and 1000 hPa when the needle is new. I vary the pressure and time until a small droplet is seen coming out from the needle into the oil. The backpressure needs to be set around 100. As the needle tip gets worn, the injection pressure has to be reduced to keep the injection volume low (about 300 hPa). After this, the needle tip is too large and is killing most of the the embryos. </li>
<li>After injection, remove the oil with tissue paper and cover the slide with embryos and&nbsp;place in the Petri dish with isotonic buffer. Place the dishes in the insectory and leave them there until the embryos hatch. They start to hatch after 2-6 days. Transfer the larvae to distilled water with the pinch of ground fish food. </li>
</ol>
Notes
DNA for injection: Plasmid DNA solution for injection was isolated using EndoFree plasmid kit. Construct plasmid and Helper plasmid mix together in right concentration, precipitated with isopropanol. The pellet was washed with 70% ethanol before resuspending in injection buffer. Before injection, clean DNA using Millex-GV column.
Izotonic buffer:
<table border="1" cellpadding="8">
<tbody>
<tr>
<td>1.68 M NaCl - 88.3 ml 1.68 M NaCl - 2.9 m 1 M Hepes -10.7 ml 1.12 M CaCl2 - 2.2 ml dH2O - 896 ml</td>
<td>OR</td>
<td>5 M NaCl - 29.67 ml 1 M KCl - 4.87 ml 1 M Hepes - 10.7 ml 1.12 M CaCl2 - 2.2 ml dH2O - 952.56 ml</td>
</tr>
</tbody>
</table>
Adjust to pH 7.2

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Injection Quartz needles</td>
<td>&nbsp;</td>
<td>Sutter Instrument</td>
<td>&nbsp;</td>
<td>O.D.- 1.0 mm, I.D.-0.70, 10 cm length, are prepared by drawing capillary tubing into a fine 3-8 um with a shaft of approximately 100-300 mm micropipette puller. </td>
</tr>
<tr>
<td>Quartz puller</td>
<td>Tool</td>
<td>Sutter Instrument Co</td>
<td>P-2000</td>
<td>Set-up: Heat-275, Fil-3, Vel-38, Del-250, Pull-141</td>
</tr>
<tr>
<td>EndoFree plasmid kit</td>
<td>&nbsp;</td>
<td>Quiagen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Isopropanol</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Millex-GV column</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>SLGV RO4 NL</td>
<td>for DNA cleaning</td>
</tr>
<tr>
<td>Construct DNA</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>0.5 mg/ml </td>
</tr>
<tr>
<td>Helper plasmid</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>0.3 mg/ml </td>
</tr>
<tr>
<td>Injection solution</td>
<td>Buffer</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>1x solution: 5mM KCl, 0.1mM sodium phosphate, ph 6. 8</td>
</tr>
<tr>
<td>Isotonic buffer</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>see recipe in the protocol section</td>
</tr>
<tr>
<td>Dessication oil</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Halocarbon oil 700:Halocarbon oil 27(1:1). Mix well. Prepare in advance of microinjection.</td>
</tr>
<tr>
<td>Blood</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>to feed mosquitos</td>
</tr>
<tr>
<td>Anopheles stephensi</td>
<td>Animal</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Mosquitos, male and female.</td>
</tr>
<tr>
<td>Drosophila culture vial</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>for egg laying</td>
</tr>
<tr>
<td>Petri dishes</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>with isotonic buffer, for embryo hatching</td>
</tr>
<tr>
<td>Fine paintbrush</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Sable # 0000</td>
</tr>
<tr>
<td>3MM Whatman paper</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Forceps #5</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>double sided tape</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Microloader</td>
<td>&nbsp;</td>
<td>Eppendorf</td>
<td>5242 956.003</td>
<td>&nbsp;</td>
<tr>
<td>Transjector</td>
<td>&nbsp;</td>
<td>Eppendorf</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Microscope</td>
<td>&nbsp;</td>
<td>Leica</td>
<td>&nbsp;</td>
<td>with moving stage and micromanipulator, set at 10x magnification </td>
</tr>		</tbody>
		</table>
		</div>
			<div>
					</div>

injection of an. stephensi embryos to generate malaria-resistant mosquitoes

The introduction of exogenous genes into the genomes of mosquitoes requires microinjection techniques tailored to the specific species of interest. This video protocol demonstrates a method used by the James laboratory to microinject DNA constructs into Anopheles stephensi embryos for the generation of transformed mosquitoes. Techniques for preparing microinjection needles, collecting and preparing embryos and performing the microinjection are illustrated.

Watch this Scientific Journal Video about Injection of An. stephensi Embryos to Generate Malaria-resistant Mosquitoes at JoVE.com

Injection of An. stephensi Embryos to Generate Malaria-resistant Mosquitoes

Anopheles stephensi mosquitoes are vectors for malaria inhabiting India and throughout Asia. This video demonstrates the technique for performing microinjections of this species with transgenes that will confer resistance to the malaria to the mosquito. Much of the methodology demonstrated in this video is applicable to microinjection techniques of other mosquito species.

The introduction of exogenous genes into the genomes of mosquitoes requires microinjection techniques tailored to the specific species of interest. This ...

injection-an-stephensi-embryos-to-generate-malaria-resistant

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12.9K vues.  University of California, Irvine (UCI). Moustiques Anopheles stephensi sont des vecteurs de la malaria qui habitent en Inde et en Asie. Cette vidéo montre la technique pour effectuer des micro-injections de cette espèce avec des transgènes qui confèrent une résistance à la malaria au moustique. Une grande partie de la méthodologie démontrée dans cette vidéo est applicable à des techniques de micro-injection d'autres espèces de moustiques.

Vidéo: Injection of An. stephensi Embryos to Generate Malaria-resistant Mosquitoes

Microinjection of A. aegypti Embryos to Obtain Transgenic Mosquitoes

In this video, Nijole Jasinskiene demonstrates the methodology employed to generate transgenic Aedes aegypti mosquitoes, which are vectors for dengue fever.  The techniques for correctly preparing microinjection needles, dessicating embryos, and performing microinjection are demonstrated.

In this video, Nijole Jasinskiene demonstrates the methodology employed to generate transgenic Aedes aegypti mosquitoes, which are vectors for dengue fever. The techniques for correctly preparing microinjection needles, dessicating embryos, and performing microinjection are demonstrated.

In this video, Nijole Jasinskiene demonstrates the methodology employed to generate transgenic Aedes aegypti mosquitoes, which are vectors for dengue ...

In Utero Intraventricular Injection and Electroporation of E16 Rat Embryos

In-utero in-vivo injection and electroporation of the embryonic rat neocortex provides a powerful tool for the manipulation of individual progenitors lining the walls of the lateral ventricle. This technique is now widely used to study the processes involved in corticogenesis by over-expressing or knocking down genes and observing the effects on cellular proliferation, migration, and differentiation. In comparison to traditional knockout strategies, in-utero electroporation provides a rapid means to manipulate a population of cells during a specific temporal window. In this video protocol, we outline the experimental methodology for preparing rats for surgery, exposing the uterine horns through laporatomy, injecting DNA into the lateral ventricles of the developing embryo, electroporating DNA into the progenitors lining the lateral wall, and caring for animals post-surgery. Our laboratory uses this protocol for surgeries on E15-E21 rats, however it is most commonly performed at E16 as shown in this video.

In-utero in-vivo injection and electroporation of the embryonic rat neocortex provides a powerful tool for the manipulation of individual progenitors ...

In Utero Intraventricular Injection and Electroporation of E15 Mouse Embryos

In-utero in-vivo injection and electroporation of the embryonic mouse neocortex provides a powerful tool for the manipulation of individual progenitors lining the walls of the lateral ventricle. This technique is now widely used to study the processes involved in corticogenesis by over-expressing or knocking down genes and observing the effects on cellular proliferation, migration, and differentiation. In comparison to traditional knockout strategies, in-utero electroporation provides a rapid means to manipulate a population of cells during a specific temporal window. In this video protocol we outline the experimental methodology for preparing mice for surgery, exposing the uterine horns through laporatomy, injecting DNA into the lateral ventricles of the developing embryo, electroporating DNA into the progenitors lining the lateral wall, and caring for animals post-surgery. Our laboratory uses this protocol for surgeries on E13-E16 mice, however, it is most commonly performed at E15, as shown in this video. 

In-utero in-vivo injection and electroporation of the embryonic mouse neocortex provides a powerful tool for the manipulation of individual progenitors ...

Microinjection of Zebrafish Embryos to Analyze Gene Function

One of the advantages of studying zebrafish is the ease and speed of manipulating protein levels in the embryo.  Morpholinos, which are synthetic oligonucleotides with antisense complementarity to target RNAs, can be added to the embryo to reduce the expression of a particular gene product.  Conversely, processed mRNA can be added to the embryo to increase levels of a gene product.  The vehicle for adding either mRNA or morpholino to an embryo is microinjection.  Microinjection is efficient and rapid, allowing for the injection of hundreds of embryos per hour.  This video shows all the steps involved in microinjection.  Briefly, eggs are collected immediately after being laid and lined up against a microscope slide in a Petri dish.  Next, a fine-tipped needle loaded with injection material is connected to a microinjector and an air source, and the microinjector controls are adjusted to produce a desirable injection volume.  Finally, the needle is plunged into the embryo's yolk and the morpholino or mRNA is expelled.

This video shows how morpholino or mRNA can be injected into zebrafish embryos at the one-cell stage to decrease or increase the level of specific gene products during subsequent development.

One of the advantages of studying zebrafish is the ease and speed of manipulating protein levels in the embryo.  Morpholinos, which are synthetic ...

RNAi Interference by dsRNA Injection into Drosophila Embryos

Genetic screening is one of the most powerful methods available for gaining insights into complex biological process 1. Over the years many improvements and tools for genetic manipulation have become available in Drosophila 2. Soon after the initial discovery by Frie and Mello 3 that double stranded RNA can be used to knockdown the activity of individual genes in Caenorhabditis elegans, RNA interference (RNAi) was shown to provide a powerful reverse genetic approach to analyze gene functions in Drosophila organ development 4, 5.
Many organs, including lung, kidney, liver, and vascular system, are composed of branched tubular networks that transport vital fluids or gases 6, 7. The analysis of Drosophila tracheal formation provides an excellent model system to study the morphogenesis of other tubular organs 8. The Berkeley Drosophila genome project has revealed hundreds of genes that are expressed in the tracheal system. To study the molecular and cellular mechanism of tube formation, the challenge is to understand the roles of these genes in tracheal development. Here, we described a detailed method of dsRNA injection into Drosophila embryo to knockdown individual gene expression. We successfully knocked down endogenous dysfusion(dys) gene expression by dsRNA injection. Dys is a bHLH-PAS protein expressed in tracheal fusion cells, and it is required for tracheal branch fusion 9, 10. dys-RNAi completely eliminated dys expression and resulted in tracheal fusion defect. This relatively simple method provides a tool to identify genes requried for tissure and organ development in Drosophila.

RNAi Interference by dsRNA Injection into Drosophila Embryos

RNA interference has been proven very effective to analyze gene function in Drosophila tracheal development. A detailed protocol used by Jiang lab to inject dsRNA into fly embryos to knockdown gene expression is illustrated. This technique has the potential for screening genes required for tissue and organ development in Drosophila.

Genetic screening is one of the most powerful methods available for gaining insights into complex biological process 1. Over the years many improvements ...

An in vivo Crosslinking Approach to Isolate Protein Complexes From Drosophila Embryos

Many cellular processes are controlled by multisubunit protein complexes. Frequently these complexes form transiently and require native environment to assemble. Therefore, to identify these functional protein complexes, it is important to stabilize them in vivo before cell lysis and subsequent purification. Here we describe a method used to isolate large bona fide protein complexes from Drosophila embryos. This method is based on embryo permeabilization and stabilization of the complexes inside the embryos by in vivo crosslinking using a low concentration of formaldehyde, which can easily cross the cell membrane. Subsequently, the protein complex of interest is immunopurified followed by gel purification and analyzed by mass spectrometry. We illustrate this method using purification of a Tudor protein complex, which is essential for germline development. Tudor is a large protein, which contains multiple Tudor domains - small modules that interact with methylated arginines or lysines of target proteins. This method can be adapted for isolation of native protein complexes from different organisms and tissues.

An in vivo Crosslinking Approach to Isolate Protein Complexes From Drosophila Embryos

Multi-component protein complexes play crucial roles during cellular function and development. Here we describe a method used to isolate native protein complexes from Drosophila embryos after in vivo crosslinking followed by purification of the crosslinked complexes for subsequent structure-function analysis.

Many cellular processes are controlled by multisubunit protein complexes. Frequently these complexes form transiently and require native environment to ...

Toxicological Assays for Testing Effects of an Epigenetic Drug on Development, Fecundity and Survivorship of Malaria Mosquitoes

Insecticidal resistance poses a major problem for malaria control programs. Mosquitoes adapt to a wide range of changes in the environment quickly, making malaria control an omnipresent problem in tropical countries. The emergence of insecticide resistant populations warrants the exploration of novel drug target pathways and compounds for vector mosquito control. Epigenetic drugs are well established in cancer research, however not much is known about their effects on insects. This study provides a simple protocol for examining the toxicological effects of 3-Deazaneplanocin A (DZNep), an experimental epigenetic drug for cancer therapy, on the malaria vector, Anopheles gambiae. A concentration-dependent increase in mortality and decrease in size was observed in immature mosquitoes exposed to DZNep, whereas the compound reduced the fecundity of adult mosquitoes relative to control treatments. In addition, there was a drug-dependent decrease in S-adenosylhomocysteine (SAH) hydrolase activity in mosquitoes following exposure to DZNep relative to control treatments. These protocols provide the researcher with a simple, step-by-step procedure to assess multiple toxicological endpoints for an experimental drug and, in turn, demonstrate a unique multi-prong approach for exploring the toxicological effects of water-soluble epigenetic drugs or compounds of interest against vector mosquitoes and other insects.

A protocol is developed to examine the effects of an epigenetic drug DZNep on the development, fecundity and survivorship of mosquitoes. Here we describe procedures for the aqueous exposure of DZNep to immature mosquitoes and a blood-based exposure of DZNep to adult mosquitoes in addition to measuring SAH hydrolase inhibition.

Insecticidal resistance poses a major problem for malaria control programs. Mosquitoes adapt to a wide range of changes in the environment quickly, making ...

Protocols for Testing the Toxicity of Novel Insecticidal Chemistries to Mosquitoes

New classes of insecticides with novel modes of action are needed to control insecticide resistant populations of mosquitoes that transmit diseases such as Zika, dengue and malaria. Assays for rapid, high-throughput analyses of unformulated novel chemistries against mosquito larvae and adults are presented. We describe protocols for single point-dose and dose response assays to evaluate the toxicity of small molecule chemistries to the Aedes aegypti vector of Zika, dengue and yellow fever,&#160;the malaria vector, Anopheles gambiae and the northern house mosquito, Culex quinquefasciatus, on contact and via ingestion. As an example, we evaluated the toxicity of amitriptyline, a small molecule antagonist of G protein-coupled receptors, via larval, adult topical and adult blood-feeding assay. The protocols provide a starting point to investigate insecticide potential. Results are discussed in the context of additional experiments to explore product applications and mechanisms for delivery.

Protocols are described for assessing the toxicity of chemistries to immature and adult mosquitoes for development as new classes of larvicides, adulticides and endectocides. The protocols enable high-throughput testing of multiple chemistries at single-point dose and subsequent evaluation via dose response assay to determine toxicity on contact or via ingestion.

New classes of insecticides with novel modes of action are needed to control insecticide resistant populations of mosquitoes that transmit diseases such ...

Forced Salivation As a Method to Analyze Vector Competence of Mosquitoes

Vector competence is defined as the potential of a mosquito species to transmit a mosquito-borne virus (mobovirus) to a vertebrate host. Viable virus particles are transmitted during a blood meal via the saliva of an infected mosquito. Forced salivation assays allow determining the vector potential on the basis of single mosquitoes, avoiding the use of animal experiments. The method is suitable to analyze a large number of mosquitoes in one experiment within a short period of time. Forced salivation assays were used to analyze 856 individual mosquitoes trapped in Germany, including two different Culex pipiens pipiens biotypes, Culex torrentium as well as Aedes albopictus, which were experimentally infected with Zika virus (ZIKV) and incubated at 18 &#176;C or 27 &#176;C for two and three weeks. The results indicated the lack of vector competence of the different Culex taxa for ZIKV. In contrast, Aedes albopictus was susceptible to ZIKV, but only at 27 &#176;C, with transmission rates similar to an Aedes aegypti laboratory colony tested in parallel.

For efficient control of mosquito borne virus transmission, the knowledge of the vector potential of respective mosquitoes is of particular interest. We describe forced salivation as a method to analyze vector competence of Aedes albopictus and three different Culex taxa for the transmission of Zika virus.

Vector competence is defined as the potential of a mosquito species to transmit a mosquito-borne virus (mobovirus) to a vertebrate host. Viable virus ...

A Blood-Free Diet to Rear Anopheline Mosquitoes

Malaria research requires large-scale breeding and production conditions for mosquitoes (Anopheles spp.) in captivity. The sustainable and reliable production of mosquitoes is currently inhibited by the supply of fresh vertebrate blood. Alternatives to blood are required to promote efficient control strategies for malaria and other vector borne diseases that are transmitted by blood feeding insects. With this in mind, artificial liquid diets were formulated as substitutes for fresh vertebrate blood. Herein we report a blood-free artificial liquid diet that delivers feeding rates similar to blood and mimics the physiological effects of a fresh vertebrate blood meal. The diet induces ovarian and egg maturation of Anopheles mosquitoes and also produces good larval survival and development of functional adults. The formulated blood-free liquid diet is an important advance towards sustainable mosquito breeding in captivity and will reduce the maintenance costs of mosquito colonies and eliminate the need for fresh vertebrate blood.

A protocol is presented for formulation of a blood-free artificial diet to feed Anopheles mosquitoes in captivity. This diet has a similar performance to vertebrate blood and triggers oogenesis and egg maturation and produces viable adult progeny.

Malaria research requires large-scale breeding and production conditions for mosquitoes (Anopheles spp.) in captivity. The sustainable and reliable ...