The authors would like to thank Stephen Crews for dysfusion cDNA, Dys antibody and w1118 flies.

1. Embryo Collection
<ol>
<li>Set up cages at 25&deg;C using 2-4 day-old w1118 flies.Grape juice plates are changed every hour during the day to synchronize the egg collection over 1-2 day period before collection</li>
<li>Collect embryos for 1hr at 25&deg;C</li>
<li>Cut a rectangular piece of grape juice agar, cut lightly in the middle with a razor blade, leave a line in the agar</li>
<li>Use a metal probe to transfer embryos from grape juice plate to your piece of grape juice agar, line them up in a straight line with the embryo's longer axis at 45 degree angle to the line in the middle of the agar. Get a straight line of about 50 embryos. Make sure all the embryos point in the same direction, with posterior end pointing away from the line.</li>
<li>Cut a rectangular piece of double stick tape, and place it to a 18x18mm cover slip.</li>
<li>Pick up embryos with double stick tape on the cover slip</li>
<li>Place the cover slip to a glass slide, dry the embryo in air for about 10 min.</li>
<li>Cover the embryo with a thin layer of 700 Halocarbon oil, now it's ready for injection.</li>
</ol>
2. Pulling Needle
Make microinjection needles by pulling glass capillary tubes. We use a needle puller from World Precision Instrument (Model PUL-1). The needle puller program specifications are: heat: 1,delay 4.
3. Filling the Needles
Back-load needles using the Eppendorf p20 pipette fitted with Eppendorf Microloader tips, normally load 1.5-2 &mu;L dsRNA
4. Break the Needles
<ol>
<li>Before breaking the needle, place a coverslip onto a slide.</li>
<li>Prepare a slide with a drop of oil in the middle of the slide</li>
<li>Turn on the Picospritzer III picopump to adjust the air pressure</li>
<li>Break the filled needle against the edge of a cover slip, creating a sharp point.</li>
<li>When the tip is broken, step on the foot pedal of Picospritzer III picopump, some dsRNA will leak out of the needle tip.</li>
<li>Take out the slide with the coverslip.</li>
<li>Insert the needle under the oil drop in the middle of the slide prepared before.</li>
<li>Adjust the setting on the Picospritzer III picopump to get 100-200pl dsRNA when you step on the foot pedal. dsRNA can be seen as a small droplet.</li>
</ol>
5. Injection
<ol>
<li>Bring the needle tip to the posterior portion of the first blastoderm embryo into the same focal plane and inject the embryo off center around 30-50% egg length.</li>
<li>After you step on the foot pedal of the Picospritzer III picopump, a small amount of dsRNA will appear as a small dot in the injection site.</li>
</ol>
6. Phenotypic Analysis
<ol>
<li>After injection, place the slide into a covered moist chamber (plastic Petri dish) at 18&deg;C until the embryos develop to the desired embryonic stage.</li>
<li>Use probe to remove embryos from the double sided tape and push them to the edge of the cover slip. 
Wash the embryos off the slide into a collection vial with nylon mesh at the bottom using heptane, wash 3 times with PBT. 
 Dechorionate embryos in 50% bleach for 5 min, and wash 3 times with PBT. 
Transfer embryos from the collection vial to a piece of nylon mesh, and then dip the nylon mesh into the fixative solution (5ml heptane, 4.5ml PBS, 0.5ml 37% formaldehyde) to release embryos. Fix embryos in the fixative solution for 30min. 
Devitellinize embryos with methanol, transfer embryos to an eppendorf tube, and immunostain the embryos using standard protocols.</li>
<li>Embryos can also develop to appropriate larval stage.</li>
<li>Prepare a slide with a drop of Halocarbon 700 oil in the middle</li>
<li>Transfer one larvae to the slide, put a cover slip on the top</li>
<li>Observe larvae under bright field microscope.</li>
</ol>
7. Representative Results:
An example of dsRNA knock down dysfusion (dys) gene in Drosophlia embryo is shown in Fig1. GFP-dsRNA injected embryos are the negative control. Dys is a bHLH PAS transcription factor expressed in tracheal fusion cells. GFP-dsRNA injected embryos show normal tracheal fusion, and Dys protein is present in fusion cells (Figure 1A). On the other hand, dys-dsRNA injected embryos show failed branch fusion, and Dys proteins are not present in fusion cells (Figure 1B). When dsRNA injected embryos develop to larval stage, the dys-dsRNA injected larvae showed failed branch fusion (Fig.1D) compared to GFP- dsRNA injected negative control (Figure 1C). These results showed effective knock down of endogenous dys gene expression by dsRNA injection into Drosophila embryos
 <img src="/files/ftp_upload/2477/2477fig1.jpg" alt="Figure 1" /> 
Figure 1. Removal of dys function by dys-RNAi reveals tracheal fusion defects. Blastoderm embryos (w1118) were injected with either GFP-dsRNA (negative control) or dys-dsRNA and assayed for tracheal defects. (A) Stage 16 embryo injected with GFP-dsRNA and stained with &alpha;-Dys and MAb 2A12 that stains the tracheal lumen. Prominently shown is the lateral trunk, which has fused. Arrows point to lateral trunk Dys-positive fusion cells. (B) Stage 16 embryo injected with dys-dsRNA and stained with &alpha;-Dys and MAb 2A12. The embryo showed a lack of lateral trunk fusion (the asterisk indicates the normal location of a lateral-trunk fusion in control embryos). No Dys-positive cells were observed, indicating that the dys-RNA effectively abolished Dys protein. (C to D) Second-instar larvae with either GFP-dsRNA or dys-dsRNA were examined by bright-field microscopy for tracheal defects. (C) Sites of fusion are indicated by an asterisk in GFP-dsRNA injected control larvae. (D) The lateral trunk failed to fuse in the dys-RNA injected larvae, (*) indicates the normal location of a lateral trunk fusion.

<ol>
	<li>St Johnston, D., Nusslein-Volhard, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+origin+of+pattern+and+polarity+in+the+Drosophila+embryo.">The origin of pattern and polarity in the Drosophila embryo.</a> Cell. 68, 201-219 (1992).</li><li>Venken, K. J., Bellen, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emerging+technologies+for+gene+manipulation+in+Drosophila+melanogaster.">Emerging technologies for gene manipulation in Drosophila melanogaster.</a> Nat. Rev. Genet. 6, 167-178 (2005).</li><li>Fire, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potent+and+specific+genetic+interference+by+double-stranded+RNA+in+Caenorhabditis+elegans.">Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans.</a> Nature. 391, 806-811 (1998).</li><li>Kennerdell, J. R., Carthew, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+dsRNA-mediated+genetic+interference+to+demonstrate+that+frizzled+and+frizzled+2+act+in+the+wingless+pathway.">Use of dsRNA-mediated genetic interference to demonstrate that frizzled and frizzled 2 act in the wingless pathway.</a> Cell. 95, 1017-1026 (1998).</li><li>Misquitta, L., Paterson, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeted+disruption+of+gene+function+in+Drosophila+by+RNA+interference+(RNA-i):+a+role+for+nautilus+in+embryonic+somatic+muscle+formation.">Targeted disruption of gene function in Drosophila by RNA interference (RNA-i): a role for nautilus in embryonic somatic muscle formation.</a> Proc. Natl. Acad. Sci. U. S. A. 96, 1451-1456 (1999).</li><li>Horowitz, A., Simons, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Branching+morphogenesis.">Branching morphogenesis.</a> Circ. Res. 103, 784-795 (2008).</li><li>Hogan, B. L., Kolodziej, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organogenesis:+molecular+mechanisms+of+tubulogenesis.">Organogenesis: molecular mechanisms of tubulogenesis.</a> Nat. Rev. Genet. 3, 513-523 (2002).</li><li>Ghabrial, A., Luschnig, S., Metzstein, M. M., Krasnow, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Branching+morphogenesis+of+the+Drosophila+tracheal+system.">Branching morphogenesis of the Drosophila tracheal system.</a> Annu. Rev. Cell Dev. Biol. 19, 623-647 (2003).</li><li>Jiang, L., Crews, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dysfusion+transcriptional+control+of+Drosophila+tracheal+migration,+adhesion,+and+fusion.">Dysfusion transcriptional control of Drosophila tracheal migration, adhesion, and fusion.</a> Mol. Cell. Biol. 26, 6547-6556 (2006).</li><li>Jiang, L., Crews, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Drosophila+dysfusion+basic+helix-loop-helix+(bHLH)-PAS+gene+controls+tracheal+fusion+and+levels+of+the+trachealess+bHLH-PAS+protein.">The Drosophila dysfusion basic helix-loop-helix (bHLH)-PAS gene controls tracheal fusion and levels of the trachealess bHLH-PAS protein.</a> Mol. Cell. Biol. 23, 5625-5637 (2003).</li></ol>

No conflicts of interest declared.

The dsRNA injection method present here enables a very sensitive and rapid analysis of gene function in Drosophila tracheal development. This method can potentially be applied to analyze gene function for other tissue and organ development.

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		<th>Material Name</th>
		<th>Type</th>
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		<th>Catalogue Number</th>
		<th>Comment</th>
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<td>Halocarbon oil 700</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>H8898</td>
<td>&nbsp;</td>
<tr>
<td>Picospritzer III picopump</td>
<td>&nbsp;</td>
<td>Parker Precision Fluidics</td>
<td>051-0500-900</td>
<td>&nbsp;</td>
<tr>
<td>Micro-pipettes</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>21170M</td>
<td>&nbsp;</td>
<tr>
<td>Microloaders</td>
<td>&nbsp;</td>
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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.

Watch this Scientific Journal Video about RNAi Interference by dsRNA Injection into Drosophila Embryos at JoVE.com

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.

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 ...

rnai-interference-by-dsrna-injection-into-drosophila-embryos

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16.1K Views.  Oakland University. 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.

Video: RNAi Interference by dsRNA Injection into Drosophila Embryos

Injection of dsRNA into Female A. aegypti Mosquitos

Reverse genetic approaches have proven extremely useful for determining  which genes underly resistance to vector pathogens in mosquitoes.  This video protocol illustrates a method used by the James lab to inject dsRNA into female A. aegypti mosquitoes, which harbor the dengue virus.  The technique for calibrating injection needles, manipulating the injection setup, and injecting dsRNA into the thorax is illustrated.

Reverse genetic approaches have proven extremely useful for determining which genes underly resistance to vector pathogens in mosquitoes. This video protocol illustrates a method used by the James lab to inject dsRNA into female A. aegypti mosquitoes, which harbor the dengue virus. The technique for calibrating injection needles, manipulating the injection setup, and injecting dsRNA into the thorax is illustrated.

Reverse genetic approaches have proven extremely useful for determining  which genes underly resistance to vector pathogens in mosquitoes.  This video ...

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.

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 ...

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 ...

Live Dissection of Drosophila Embryos: Streamlined Methods for Screening Mutant Collections by Antibody Staining

Drosophila embryos between stages 14 and 17 of embryonic development can be readily dissected to generate "fillet" preparations. In these preparations, the central nervous system runs down the middle, and is flanked by the body walls. Many different phenotypes have been examined using such preparations. In most cases, the fillets were generated by dissection of antibody-stained fixed whole-mount embryos. These "fixed dissections" have some disadvantages, however. They are time-consuming to execute, and it is difficult to sort mutant (GFP-negative) embryos from stocks in which mutations are maintained over GFP balancer chromosomes. Since 2002, our group has been conducting deficiency and ectopic expression screens to identify ligands for orphan receptors. In order to do this, we developed streamlined protocols for live embryo dissection and antibody staining of collections containing hundreds of balanced lines. We have concluded that it is considerably more efficient to examine phenotypes in large collections of stocks by live dissection than by fixed dissection. Using the protocol described here, a single trained individual can screen up to 10 lines per day for phenotypes, examining 4-7 mutant embryos from each line under a compound microscope. This allows the identification of mutations conferring subtle, low-penetrance phenotypes, since up to 70 hemisegments per line are scored at high magnification with a 40X water-immersion lens.

Live Dissection of Drosophila Embryos: Streamlined Methods for Screening Mutant Collections by Antibody Staining

We describe a streamlined protocol for generating "fillet" preparations of Drosophila embryos of specific genotypes. This protocol allows efficient execution of a variety of genetic screens. It also allows excellent visualization of structures in the late embryo.

Drosophila embryos between stages 14 and 17 of embryonic development can be readily dissected to generate "fillet" preparations.  In these preparations, ...

In-vivo Centrifugation of Drosophila Embryos

A major strategy for purifying and isolating different types of intracellular organelles is to separate them from each other based on differences in buoyant density. However, when cells are disrupted prior to centrifugation, proteins and organelles in this non-native environment often inappropriately stick to each other. Here we describe a method to separate organelles by density in intact, living Drosophila embryos. Early embryos before cellularization are harvested from population cages, and their outer egg shells are removed by treatment with 50% bleach. Embryos are then transferred to a small agar plate and inserted, posterior end first, into small vertical holes in the agar. The plates containing embedded embryos are centrifuged for 30 min at 3000g. The agar supports the embryos and keeps them in a defined orientation. Afterwards, the embryos are dug out of the agar with a blunt needle. Centrifugation separates major organelles into distinct layers, a stratification easily visible by bright-field microscopy. A number of fluorescent markers are available to confirm successful stratification in living embryos. Proteins associated with certain organelles will be enriched in a particular layer, demonstrating colocalization. Individual layers can be recovered for biochemical analysis or transplantation into donor eggs. This technique is applicable for organelle separation in other large cells, including the eggs and oocytes of diverse species.

In-vivo Centrifugation of Drosophila Embryos

We describe a method to separate organelles by density in living Drosophila embryos. Embryos are embedded in agar and centrifuged. This technique yields reproducible separation of major organelles along the anterior-posterior embryo axis. This method facilitates colocalization experiments and yields organelle fractions for biochemical analysis and transplantation experiments.

A major strategy for purifying and isolating different types of intracellular organelles is to separate them from each other based on differences in ...

Bacterial Delivery of RNAi Effectors: Transkingdom RNAi

RNA interference (RNAi) represents a high effective mechanism for specific inhibition of mRNA expression. Besides its potential as a powerful laboratory tool, the RNAi pathway appears to be promising for therapeutic utilization. For development of RNA interference (RNAi)-based therapies, delivery of RNAi-mediating agents to target cells is one of the major obstacles. A novel strategy to overcome this hurdle is transkingdom RNAi (tkRNAi). This technology uses non-pathogenic bacteria, e.g. Escherichia coli, to produce and deliver therapeutic short hairpin RNA (shRNA) into target cells to induce RNAi. A first-generation tkRNAi-mediating vector, TRIP, contains the bacteriophage T7 promoter for expression regulation of a therapeutic shRNA of interest. Furthermore, TRIP has the Inv locus from Yersinia pseudotuberculosis that encodes invasin, which permits natural noninvasive bacteria to enter &beta;1-integrin-positive mammalian cells and the HlyA gene from Listeria monocytogenes, which produces listeriolysin O. This enzyme allows the therapeutic shRNA to escape from entry vesicles within the cytoplasm of the target cell. TRIP constructs are introduced into a competent non-pathogenic Escherichia coli strain, which encodes T7 RNA polymerase necessary for the T7 promoter-driven synthesis of shRNAs. A well-characterized cancer-associated target molecule for different RNAi strategies is ABCB1 (MDR1/P-glycoprotein, MDR1/P-gp). This ABC-transporter acts as a drug extrusion pump and mediates the "classical" ABCB1-mediated multidrug resistance (MDR) phenotype of human cancer cells which is characterized by a specific cross resistance pattern. Different ABCB1-expressing MDR cancer cells were treated with anti-ABCB1 shRNA expression vector bearing E. coli. This procedure resulted in activation of the RNAi pathways within the cancer cells and a considerable down regulation of the ABCB1 encoding mRNA as well as the corresponding drug extrusion pump. Accordingly, drug accumulation was enhanced in the pristine drug-resistant cancer cells and the MDR phenotype was reversed. By means of this model the data provide the proof-of-concept that tkRNAi is suitable for modulation of cancer-associated factors, e.g. ABCB1, in human cancer cells.

For development of RNA interference (RNAi)-based therapies, a novel strategy was developed, transkingdom RNAi (tkRNAi). This technology uses non-pathogenic bacteria to produce and deliver therapeutic short hairpin RNA (shRNA) into target cells. Here, tkRNAi was successfully applied for reversal of classical ABCB1-mediated multidrug resistance (MDR) of cancer cells.

RNA interference (RNAi) represents a high effective mechanism for specific inhibition of mRNA expression. Besides its potential as a powerful laboratory ...

Intraperitoneal Injection into Adult Zebrafish

A convenient method for chemically treating zebrafish is to introduce the reagent into the tank water, where it will be taken up by the fish. However, this method makes it difficult to know how much reagent is absorbed or taken up per fish. Some experimental questions, particularly those related to metabolic studies, may be better addressed by delivering a defined quantity to each fish, based on weight. Here we present a method for intraperitoneal (IP) injection into adult zebrafish. Injection is into the abdominal cavity, posterior to the pelvic girdle. This procedure is adapted from veterinary methods used for larger fish. It is safe, as we have observed zero mortality. Additionally, we have seen bleeding at the injection site in only 5 out of 127 injections, and in each of those cases the bleeding was brief, lasting several seconds, and the quantity of blood lost was small. Success with this procedure requires gentle handling of the fish through several steps including fasting, weighing, anesthetizing, injection, and recovery. Precautions are required to minimize stress throughout the procedure. Our precautions include using a small injection volume and a 35G needle. We use Cortland salt solution as the vehicle, which is osmotically balanced for freshwater fish. Aeration of the gills is maintained during the injection procedure by first bringing the fish into a surgical plane of anesthesia, which allows slow operculum movements, and second, by holding the fish in a trough within a water-saturated sponge during the injection itself. We demonstrate the utility of IP injection by injecting glucose and monitoring the rise in blood glucose level and its subsequent return to normal. As stress is known to increase blood glucose in teleost fish, we compare blood glucose levels in vehicle-injected and non-injected adults and show that the procedure does not cause a significant rise in blood glucose.

We demonstrate intraperitoneal injection into adult zebrafish. We use a 10 &mu;l NanoFil microsyringe controlled by a Micro4 controller and UltraMicroPump III. This demonstration includes the use of cold water as an anesthetic.

A convenient method for chemically treating zebrafish is to introduce the reagent into the tank water, where it will be taken up by the fish. However, ...

Upright Imaging of Drosophila Embryos

Several well-known morphogenetic gradients and cellular movements occur along the dorsal/ventral axis of the Drosophila embryo. However, the current techniques used to view such processes are somewhat limited. The following protocol describes a new technique for mounting fixed and labeled Drosophila embryos for coronal viewing with confocal imaging. This method consists of embedding embryos between two layers of glycerin jelly mounting media, and imaging jelly strips positioned upright. The first step for sandwiching the embryos is to make a thin bedding of glycerin jelly on a slide. Next, embryos are carefully aligned on this surface and covered with a second layer of jelly. After the second layer is solidified, strips of jelly are cut and flipped upright for imaging. Alternatives are described for visualizing the embryos depending upon the type of microscope stand to be used. Since all cells along the dorsal-ventral axis are imaged within a single confocal Z-plane, our method allows precise measurement and comparison of fluorescent signals without photobleaching or light scattering common to 3D reconstructions of longitudinally mounted embryos.

Upright Imaging of Drosophila Embryos

Here we present a mounting protocol for stained Drosophila embryos in an upright position that allows imaging of cross-sections using Confocal microscopy.

Several well-known morphogenetic gradients and cellular movements occur along the dorsal/ventral axis of the Drosophila embryo. However, the current ...

Primary Cell Cultures from Drosophila Gastrula Embryos

Here we describe a method for preparing and culturing primary cells dissociated from Drosophila gastrula embryos. In brief, a large amount of staged embryos from young and healthy flies are collected, sterilized, and then physically dissociated into a single cell suspension using a glass homogenizer. After being plated on culture plates or chamber slides at an appropriate density in culture medium, these cells can further differentiate into several morphologically-distinct cell types, which can be identified by their specific cell markers. Furthermore, we present conditions for treating these cells with double stranded (ds) RNAs to elicit gene knockdown. Efficient RNAi in Drosophila primary cells is accomplished by simply bathing the cells in dsRNA-containing culture medium. The ability to carry out effective RNAi perturbation, together with other molecular, biochemical, cell imaging analyses, will allow a variety of questions to be answered in Drosophila primary cells, especially those related to differentiated muscle and neuronal cells.

Primary Cell Cultures from Drosophila Gastrula Embryos

We provide a detailed protocol for preparing primary cells dissociated from Drosophila embryos. The ability to carry out the effective RNAi perturbation, together with other molecular, biochemical and cell imaging methods will allow a variety of questions to be addressed in Drosophila primary cells.

Here we describe a method for preparing and culturing primary cells dissociated from Drosophila gastrula embryos.   In brief, a large amount of staged ...

Imaging Cell Shape Change in Living Drosophila Embryos

The developing Drosophila melanogaster embryo undergoes a number of cell shape changes that are highly amenable to live confocal imaging. Cell shape changes in the fly are analogous to those in higher organisms, and they drive tissue morphogenesis. So, in many cases, their study has direct implications for understanding human disease (Table 1)1-5. On the sub-cellular scale, these cell shape changes are the product of activities ranging from gene expression to signal transduction, cell polarity, cytoskeletal remodeling and membrane trafficking. Thus, the Drosophila embryo provides not only the context to evaluate cell shape changes as they relate to tissue morphogenesis, but also offers a completely physiological environment to study the sub-cellular activities that shape cells.
The protocol described here is designed to image a specific cell shape change called cellularization. Cellularization is a process of dramatic plasma membrane growth, and it ultimately converts the syncytial embryo into the cellular blastoderm. That is, at interphase of mitotic cycle 14, the plasma membrane simultaneously invaginates around each of ~6000 cortically anchored nuclei to generate a sheet of primary epithelial cells. Counter to previous suggestions, cellularization is not driven by Myosin-2 contractility6, but is instead fueled largely by exocytosis of membrane from internal stores7. Thus, cellularization is an excellent system for studying membrane trafficking during cell shape changes that require plasma membrane invagination or expansion, such as cytokinesis or transverse-tubule (T-tubule) morphogenesis in muscle.
Note that this protocol is easily applied to the imaging of other cell shape changes in the fly embryo, and only requires slight adaptations such as changing the stage of embryo collection, or using "embryo glue" to mount the embryo in a specific orientation (Table 1)8-19. In all cases, the workflow is basically the same (Figure 1). Standard methods for cloning and Drosophila transgenesis are used to prepare stable fly stocks that express a protein of interest, fused to Green Fluorescent Protein (GFP) or its variants, and these flies provide a renewable source of embryos. Alternatively, fluorescent proteins/probes are directly introduced into fly embryos via straightforward micro-injection techniques9-10. Then, depending on the developmental event and cell shape change to be imaged, embryos are collected and staged by morphology on a dissecting microscope, and finally positioned and mounted for time-lapse imaging on a confocal microscope.

Imaging Cell Shape Change in Living Drosophila Embryos

Early development of the fruit fly, Drosophila melanogaster, is characterized by a number of cell shape changes that are well suited for imaging approaches. This article will describe basic tools and methods required for live confocal imaging of Drosophila embryos, and will focus on a cell shape change called cellularization.

The developing Drosophila melanogaster embryo undergoes a number of cell shape changes that are highly amenable to live confocal imaging.  Cell shape ...

RNAi Interference by dsRNA Injection into Drosophila Embryos

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In Utero Intraventricular Injection and Electroporation of E16 Rat Embryos

Live Dissection of Drosophila Embryos: Streamlined Methods for Screening Mutant Collections by Antibody Staining

In-vivo Centrifugation of Drosophila Embryos

Bacterial Delivery of RNAi Effectors: Transkingdom RNAi

Intraperitoneal Injection into Adult Zebrafish

Upright Imaging of Drosophila Embryos

Primary Cell Cultures from Drosophila Gastrula Embryos

Imaging Cell Shape Change in Living Drosophila Embryos