We would like to thank Dr. Michael Baker for his help in generating constructs for gene knock-in and for providing the time-lapse movies of growing sensory projections. We would also like to thank Virginia Vandelinder for technical assistance with the pneumatic gun experiments.

Particles can be coated with different reagents, such as dsRNA molecules, DNA plasmids or dyes. The type and diameter of particles are chosen according to the reagent and the depth of the target cells in the tissue: larger particles penetrate further, but may cause some damage to the tissue.
1. Preparation of dsRNA coated particles
<ol>
<li>Place 100% isopropanol on ice.</li>
<li>Resuspend 5 mg gold particles (S1600ri, Seashell Technology, LLC; average diameter 1.6 &micro;m) in 100 ml binding buffer. When solution is ready, continue to the next step.</li>
<li>Dilute the particle solution by adding 100 &micro;l of binding buffer, vortex briefly and sonicate for 1-2 min to avoid clumping.</li>
<li>Add 5-10&micro;g of dsRNA/siRNA (dsRNAs/ siRNA should be dissolved in water to a concentration of ~1&micro;g/&micro;l).</li>
<li>Vortex and leave at room temperature for 2 min. These concentration and time interval result in siRNA saturated gold particles.</li>
<li>Pellet the siRNA/gold particle complexes by centrifugation at ~2,500 rpm in a bench top centrifuge for ~ 15 sec.</li>
<li>Remove the supernatant and gently add 750 ml cold isopropanol with minimal disruption of the pellet. Spin briefly and remove the supernatant.</li>
<li>Resuspend the gold particles in 100 &micro;l cold 100% isopropanol, then sonicate briefly in a bath sonicator (2-3 pulses) to break up particle agglomerates. Last, pour the suspended particles onto a glass slide and allow to dry at room temperature.</li>
</ol>
2. Preparing the experimental setup for a specific assay
<ol>
<li>Each gun has a different nozzle aperture diameter, ranging from a minimum of ~50&micro;m up to ~3mm. The specific to be used for the gun is therefore chosen according to the area of tissue to be targeted.</li>
<li>The He pressure is adjusted for the depth in the tissue of the target cells, generally up to ~100&micro;m (higher pressures can deliver the particles deeper). The distance between the embryo and the tip of the nozzle also affects the penetration depth, as gold particles loose momentum in air.</li>
</ol>
3. Loading the gun with the pre-coated particles
Particles should be loaded as a dry powder into the tygon tubing particle injection lines connected to the manifold. This tubing, which should be kept in a dry atmosphere at 4&deg;C when not in use, can be re-used in additional experiments with the same reagents. Our experimental setup can deliver up to two different reagents per assay through separate ports in the manifold.
<ol>
<li>Scrape the dried coated particles from the glass slides using the edge of a glass cover slip or a razor blade before loading them into the tygon tubing line. This tygon tubing will be specific only to this reagent to avoid cross contamination.</li>
<li>As you load the particles, bend the tubing into a U shape close to the connector, to keep the particles from spreading along the whole tubing and concentrated close to the connector. Pick up the particles with a small spatula or a piece of folded weigh paper, and load about half of them into the tubing for each series of embryos. Tap the tubing during the loading step to spread the particles evenly.</li>
</ol>
4. Animal Preparation
Before and after the gold particle delivery, the embryos are kept in sterile artificial pond water at room temperature.
<ol>
<li>Place the embryos, ventral side up, in a groove carved into a flat, 5mm-thick piece of silicone rubber (Sylgard 184, Dow Corning, Midland, MI) and anaesthetize them in a solution of 8% ethanol in sterile artificial pond water (younger embryos at stages E6-E8 can remain in artificial pond water with no ethanol throughout the experiment).</li>
<li>Immediately before shooting the particles, lower the bath level to uncover the ventral surface of the embryos by removing part of the solution. Place a piece of tissue paper with a small hole cut in the middle on top of it to stabilize it and to keep its surface from drying.</li>
</ol>
5. Delivery of coated particles into the target tissue
One load of particles can typically be used for up to ten shots, with a single shot usually delivering on the order of a few hundred particles.
<ol>
<li>Generate a shot by opening one of the valves for 0.3 s, causing the injection of a bolus of particles from the corresponding tubing line into the gun.</li>
<li>Tap the tubing gently between the shots to dislodge particles from the tubing wall and thus facilitate their injection into the He stream of the gun.</li>
<li>To cover the area of tissue of interest, multiple shots may be required.</li>
<li>After the particle delivery, place the embryos back into artificial pond water, preferably one embryo per well in a multi-well plate.</li>
</ol>
6. Immunostaining and neuronal labeling
Keep the embryos at room temperature and in darkness for 1 to 3 days after the particle delivery, until RNAi (or ectopic expression) is achieved. We then carry out one of the following procedures on the experimental specimens and controls:
<ol>
<li>In situ hybridization to assay for the presence or absence of Netrin mRNA. Digoxigenin-labeled leech netrin riboprobes are hybridized to whole leech embryos.</li>
<li>Immunocytochemistry to assay for Netrin protein and other proteins which are unique to neuronal tissue (such as anti acetylated tubulin). The procedure is performed also on whole-mount embryos.</li>
<li>Microinjections of lipophilic dyes (DiI and DiO) into single neurons, for dye-fills to label the complete arbors of the neurons of interest (mechanosensory pressure neurons in our case) in treated and control segments. This assay is performed on live embryos (intact or dissected).</li>
</ol>

<ol>
	<li>Baker, M. W., Macagno, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNAi+of+the+receptor+tyrosine+phosphatase+HmLAR2+in+a+single+cell+of+an+intact+leech+embryo+leads+to+growth-cone+collapse.">RNAi of the receptor tyrosine phosphatase HmLAR2 in a single cell of an intact leech embryo leads to growth-cone collapse.</a> Current Biology. 10, 1071-1074 (2000).</li><li>Baker, M. W., Macagno, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+Hirudo+medicinalis+DNA+Promoters+for+Targeted+Gene+Expression.">Characterization of Hirudo medicinalis DNA Promoters for Targeted Gene Expression.</a> Journal of Neuroscience Methods. 156, 145-153 (2006).</li><li>Gan, W. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+expression+of+a+leech+netrin+suggests+roles+in+the+formation+of+longitudinal+nerve+tracts+and+in+regional+innervation+of+peripheral+targets.">Cellular expression of a leech netrin suggests roles in the formation of longitudinal nerve tracts and in regional innervation of peripheral targets.</a> Journal of Neurobiology. 40, 103-115 (1999).</li><li>Juven-Gershon, T., Cheng, S., Kadonaga, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rational+design+of+a+super+core+promoter+that+enhances+gene+expression.">Rational design of a super core promoter that enhances gene expression.</a> Nature Methods. 3, 917-922 (2006).</li><li>Rinberg, D., Simonnet, C., Groisman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pneumatic+capillary+gun+for+ballistic+delivery+of+microparticles.">Pneumatic capillary gun for ballistic delivery of microparticles.</a> Applied Physics Letters. 87, 014103 (2005).</li><li>Shefi, O., Simonnet, C., Baker, M. W., Glass, J. R., Macagno, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microtargeted+gene+silencing+and+ectopic+expression+in+live+embryos+using+biolistic+delivery+with+a+pneumatic+capillary+gun.">Microtargeted gene silencing and ectopic expression in live embryos using biolistic delivery with a pneumatic capillary gun.</a> Journal of Neuroscience. 26, 6119-6123 (2006).</li></ol>

In this demonstration, we used the pneumatic capillary gun to deliver gold particles into cells in small localized volume of a live leech embryo to knock-in and knock-down genes. The target region generally had a diameter of ~150 &#181;m and particles were found ~15 &#181;m around the mean penetration depth, which was adjustable between 0 and 50 &#181;m. When the particles were coated with dsRNA molecules of the axon guidance factor netrin, they caused clearly visible knock-down of netrin expression that only occurred in...

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		<div>
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		<tr>
		<th>Material Name</th>
		<th>Type</th>
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		<th>Catalogue Number</th>
		<th>Comment</th>
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<td>gold particles</td>
<td>Other</td>
<td>Seashell Technology, LLC</td>
<td>S1600ri</td>
<td>&nbsp;</td>
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<td>binding buffer</td>
<td>Reagent</td>
<td>Seashell Technology, LLC</td>
<td>&nbsp;</td>
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<td>silicone rubber </td>
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localized rnai and ectopic gene expression in the medicinal leech

In this video, we show the use of a pneumatic capillary gun for the accurate biolistic delivery of reagents into live tissue. We use the procedure to perturb gene expression patterns in selected segments of leech embryos, leaving the untreated segments as internal controls.
The pneumatic capillary gun can be used to reach internal layers of cells at early stages of development without opening the specimen. As a method for localized introduction of substances into living tissues, the biolistic delivery with the gun has several advantages: it is fast, contact-free and non-destructive. In addition, a single capillary gun can be used for independent delivery of different substances. The delivery region can have lateral dimensions of ~50-150 &#181;m and extends over ~15 &#181;m around the mean penetration depth, which is adjustable between 0 and 50 &#181;m. This delivery has the advantage of being able to target a limited number of cells in a selected location intermediate between single cell knock down by microinjection and systemic knockdown through extracellular injections or by means of genetic approaches.
For knocking down or knocking in the expression of the axon guidance molecule Netrin, which is naturally expressed by some central neurons and in the ventral body wall, but not the dorsal domain, we deliver molecules of dsRNA or plasmid-DNA into the body wall and central ganglia. This procedure includes the following steps: (i) preparation of the experimental setup for a specific assay (adjusting the accelerating pressure), (ii) coating the particles with molecules of dsRNA or DNA, (iii) loading the coated particles into the gun, up to two reagents in one assay, (iv) preparing the animals for the particle delivery, (v) delivery of coated particles into the target tissue (body wall or ganglia), and (vi) processing the embryos (immunostaining, immunohistochemistry and neuronal labeling) to visualize the results, usually 2 to 3 days after the delivery.
When the particles were coated with netrin dsRNA, they caused clearly visible knock-down of netrin expression that only occurred in cells containing particles (usually, 1-2 particles per cell). Particles coated with a plasmid encoding EGFP induced fluorescence in neuronal cells when they stopped in their nuclei.

Watch this Scientific Journal Video about Localized RNAi and Ectopic Gene Expression in the Medicinal Leech at JoVE.com

Localized RNAi and Ectopic Gene Expression in the Medicinal Leech

In this video, we show a procedure for an accurate biolistic delivery of reagents into live tissue with a novel miniature gene gun. We are knocking down the expression of the axon guidance molecule Netrin in leech embryos by delivering molecules of dsRNA into the ventral body wall and ganglia of single segments.

In this video, we show the use of a pneumatic capillary gun for the accurate biolistic delivery of reagents into live tissue. We use the procedure to ...

localized-rnai-and-ectopic-gene-expression-in-the-medicinal-leech

Research

JoVE Journal

Biology

9.5K Views.  University of California San Diego - UCSD. In this video, we show a procedure for an accurate biolistic delivery of reagents into live tissue with a novel miniature gene gun. We are knocking down the expression of the axon guidance molecule Netrin in leech embryos by delivering molecules of dsRNA into the ventral body wall and ganglia of single segments.

Video: Localized RNAi and Ectopic Gene Expression in the Medicinal Leech

The Preparation of Primary Hematopoietic Cell Cultures From Murine Bone Marrow for Electroporation

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell  electroporation system and Gene Pulser  electroporation buffer were specifically developed to transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells.This video demonstrates how to establish primary hematopoietic cell cultures from murine bone marrow, and then prepare them for electroporation in the MXcell system. We begin by isolating femur and tibia. Bone marrow from both femur and tibia are then harvested and cultures are established. Cultured bone marrow cells are then transfected and analyzed.

This procedure describes how to establish primary hematopoietic cell cultures from murine bone marrow and is followed by transfection using the Gene Pulser MXCell electroporation system.

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Spinal Cord Electrophysiology

The neonatal mouse spinal cord is a model for studying the development of neural circuitries and locomotor movement. We demonstrate the spinal cord dissection and preparation of recording bath artificial cerebrospinal fluid used for locomotor studies. Once dissected, the spinal cord ventral nerve roots can be attached to a recording electrode to record the electrophysiologic signals of the central pattern generating circuitry within the lumbar cord.

A demonstration of the isolation of neonatal mouse spinal cord for electrophysiologic studies.

The neonatal mouse spinal cord is a model for studying the development of neural circuitries and locomotor movement. We demonstrate the spinal cord ...

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

Robotics and Dynamic Image Analysis for Studies of Gene Expression in Plant Tissues

Gene expression in plant tissues is typically studied by destructive extraction of compounds from plant tissues for in vitro analyses. The methods presented here utilize the green fluorescent protein (gfp) gene for continual monitoring of gene expression in the same pieces of tissues, over time. The gfp gene was placed under regulatory control of different promoters and introduced into lima bean cotyledonary tissues via particle bombardment. Cotyledons were then placed on a robotic image collection system, which consisted of a fluorescence dissecting microscope with a digital camera and a 2-dimensional robotics platform custom-designed to allow secure attachment of culture dishes. Images were collected from cotyledonary tissues every hour for 100 hours to generate expression profiles for each promoter. Each collected series of 100 images was first subjected to manual image alignment using ImageReady to make certain that GFP-expressing foci were consistently retained within selected fields of analysis. Specific regions of the series measuring 300 x 400 pixels, were then selected for further analysis to provide GFP Intensity measurements using ImageJ software. Batch images were separated into the red, green and blue channels and GFP-expressing areas were identified using the threshold feature of ImageJ. After subtracting the background fluorescence (subtraction of gray values of non-expressing pixels from every pixel) in the respective red and green channels, GFP intensity was calculated by multiplying the mean grayscale value per pixel by the total number of GFP-expressing pixels in each channel, and then adding those values for both the red and green channels. GFP Intensity values were collected for all 100 time points to yield expression profiles. Variations in GFP expression profiles resulted from differences in factors such as promoter strength, presence of a silencing suppressor, or nature of the promoter. In addition to quantification of GFP intensity, the image series were also used to generate time-lapse animations using ImageReady. Time-lapse animations revealed that the clear majority of cells displayed a relatively rapid increase in GFP expression, followed by a slow decline. Some cells occasionally displayed a sudden loss of fluorescence, which may be associated with rapid cell death. Apparent transport of GFP across the membrane and cell wall to adjacent cells was also observed. Time lapse animations provided additional information that could not otherwise be obtained using GFP Intensity profiles or single time point image collections.

We report a method for introduction, tracking and quantitative analysis of GFP expression in plant cells. This method utilizes a custom-designed robotics system for semi-continuous image collection from large numbers of samples, over time. We also demonstrate the use of ImageJ and ImageReady for analysis of image series.

Gene expression in plant tissues is typically studied by destructive extraction of compounds from plant tissues for in vitro analyses. The methods ...

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only to study the effects of downregulating single genes, but also to interrogate signaling pathways and other complex interaction networks.  These pathway analyses require both the use of relevant cellular models and methods that cause less perturbation to the cellular physiology.  Electroporation is increasingly being used as an effective way to introduce siRNA and other nucleic acids into difficult to transfect cell lines and primary cells without altering the signaling pathway under investigation. There are multiple critical steps to a successful siRNA experiment, and there are ways to simplify the work while improving the data quality at several experimental stages.  To help you get started with your siRNA mediated gene knockdown project, we will demonstrate how to perform a pathway study complete from collecting and counting the cells prior to electroporation through post transfection real-time PCR gene expression analysis.  The following study investigates the role of the transcriptional activator STAT6 in IL-4 dependent gene expression of CCL17 in a Burkitt lymphoma cell line (Namalwa).  The techniques demonstrated are useful for a wide range of siRNA-based experiments on both adherent and suspension cells.  We will also show how to streamline cell counting with the TC10 automated cell counter, how to electroporate multiple samples simultaneously using the MXcell electroporation system, and how to simultaneously assess RNA quality and quantity with the Experion automated electrophoresis system.

This procedure describes a quick and easy workflow to introduce siRNA into difficult to transfect cell lines and follow gene expression by real-time PCR. Use of an automated cell counter, multi-well electroporation plate, and automated electrophoresis station provide quick and reliable results without the need for expensive robotic handling.

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only ...

Paraffin-Embedded and Frozen Sections of Drosophila Adult Muscles

The molecular characterization of muscular dystrophies and myopathies in humans has revealed the complexity of muscle disease and genetic analysis of muscle specification, formation and function in model systems has provided valuable insight into muscle physiology. Therefore, identifying and characterizing molecular mechanisms that underlie muscle damage is critical. The structure of adult Drosophila multi-fiber muscles resemble vertebrate striated muscles 1 and the genetic tractability of Drosophila has made it a great system to analyze dystrophic muscle morphology and characterize the processes affecting muscular function in ageing adult flies 2. Here we present the histological technique for preparing paraffin-embedded and frozen sections of Drosophila thoracic muscles. These preparations allow for the tissue to be stained with classical histological stains and labeled with protein detecting dyes, and specifically cryosections are ideal for immunohistochemical detection of proteins in intact muscles. This allows for analysis of muscle tissue structure, identification of morphological defects, and detection of the expression pattern for muscle/neuron-specific proteins in Drosophila adult muscles. These techniques can also be slightly modified for sectioning of other body parts.

Paraffin-Embedded and Frozen Sections of Drosophila Adult Muscles

Identification of mechanisms underlying muscle damage is crucial. Here we present the histological technique for preparing paraffin-embedded and frozen sections of Drosophila thoracic muscles. This allows analysis of muscle morphology and localization of protein and other muscle cell components.

The molecular characterization of muscular dystrophies and myopathies in humans has revealed the complexity of muscle disease and genetic analysis of ...

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.
Telomerase is a specialized reverse transcriptase1 that adds short DNA repeats, called telomeres, to the 3' end of linear chromosomes2 that serve to protect them from end-to-end fusion and degradation. Following DNA replication, a short segment is lost at the end of the chromosome3 and without telomerase, cells continue dividing until eventually reaching their Hayflick Limit4. Additionally, telomerase is dormant in most somatic cells5 in adults, but is active in cancer cells6 where it promotes cell immortality7.
The minimal telomerase enzyme consists of two core components: the protein subunit (TERT), which comprises the catalytic subunit of the enzyme and an integral RNA component (TER), which contains the template TERT uses to synthesize telomeres8,9. Prior to 2008, only structures for individual telomerase domains had been solved10,11. A major breakthrough in this field came from the determination of the crystal structure of the active12, catalytic subunit of T. castaneum telomerase, TcTERT1.
Here, we present methods for producing large quantities of the active, soluble TcTERT for structural and biochemical studies, and the reconstitution of the telomerase RNP complex in vitro for telomerase activity assays. An overview of the experimental methods used is shown in Figure 1.

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more ...

RNAi Mediated Gene Knockdown and Transgenesis by Microinjection in the Necromenic Nematode Pristionchus pacificus

Although it is increasingly affordable for emerging model organisms to obtain completely sequenced genomes, further in-depth gene function and expression analyses by RNA interference and stable transgenesis remain limited in many species due to the particular anatomy and molecular cellular biology of the organism. For example, outside of the crown group Caenorhabditis that includes Caenorhabditis elegans3, stably transmitted transgenic lines in non-Caenorhabditis species have not been reported in this specious phylum (Nematoda), with the exception of Strongyloides stercoralis4 and Pristionchus pacificus5. To facilitate the expanding role of P. pacificus in the study of development, evolution, and behavior6-7, we describe here the current methods to use microinjection for making transgenic animals and gene knock down by RNAi. Like the gonads of C. elegans and most other nematodes, the gonads of P. pacificus is syncitial and capable of incorporating DNA and RNA into the oocytes when delivered by direct microinjection. Unlike C. elegans however, stable transgene inheritance and somatic expression in P. pacificus requires the addition of self genomic DNA digested with endonucleases complementary to the ends of target transgenes and coinjection markers5. The addition of carrier genomic DNA is similar to the requirement for transgene expression in Strongyloides stercoralis4 and in the germ cells of C. elegans. However, it is not clear if the specific requirement for the animals' own genomic DNA is because P. pacificus soma is very efficient at silencing non-complex multi-copy genes or that extrachromosomal arrays in P. pacificus require genomic sequences for proper kinetochore assembly during mitosis. The ventral migration of the two-armed (didelphic) gonads in hermaphrodites further complicates the ability to inject both gonads in individual worms8. We also demonstrate the use of microinjection to knockdown a dominant mutant (roller,tu92) by injecting double-stranded RNA (dsRNA) into the gonads to obtain non-rolling F1 progeny. Unlike C. elegans, but like most other nematodes, P. pacificus PS312 is not receptive to systemic RNAi via feeding and soaking and therefore dsRNA must be administered by microinjection into the syncitial gonads. In this current study, we hope to describe the microinjection process needed to transform a Ppa-egl-4 promoter::GFP fusion reporter and knockdown a dominant roller prl-1 (tu92) mutant in a visually informative protocol.

RNAi Mediated Gene Knockdown and Transgenesis by Microinjection in the Necromenic Nematode Pristionchus pacificus

In model organisms, transgenesis can manipulate gene functions while RNAi can knockdown specific mRNA transcripts 1-2. This protocol aims to illustrate the techniques needed to introduce stably transmitted DNA and transient double stranded RNA into the necromenic nematode Pristionchus pacificus for studies in evolutionary, developmental, and behavioral biology.

Although it is increasingly affordable for emerging model organisms to obtain completely sequenced genomes, further in-depth gene function and expression ...

Analysis of Global RNA Synthesis at the Single Cell Level following Hypoxia

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a particular transcriptional program in order to mount an appropriate and coordinated cellular response. The cell possesses several oxygen sensor enzymes that require molecular oxygen as cofactor for their activity. These range from prolyl-hydroxylases to histone demethylases. The majority of studies analyzing cellular responses to hypoxia are based on cellular populations and average studies, and as such single cell analysis of hypoxic cells are seldom performed. Here we describe a method of analysis of global RNA synthesis at the single cell level in hypoxia by using Click-iT RNA imaging kits in an oxygen controlled workstation, followed by microscopy analysis and quantification.&nbsp; Using cancer cells exposed to hypoxia for different lengths of time, RNA is labeled and measured in each cell. This analysis allows the visualization of temporal and cell-to-cell changes in global RNA synthesis following hypoxic stress.

We describe a technique for analysis of global RNA synthesis in hypoxia using imaging. Click-chemistry labeling of RNA has not previously been performed under hypoxia and allows visualization of global RNA changes at the single cell level. This approach complements the existing averaged RNA techniques, allowing direct visualization of cell-to-cell changes in global RNA synthesis.

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a ...

Measurement of Metabolic Rate in Drosophila using Respirometry

Metabolic disorders are a frequent problem affecting human health. Therefore, understanding the mechanisms that regulate metabolism is a crucial scientific task. Many disease causing genes in humans have a fly homologue, making Drosophila a good model to study signaling pathways involved in the development of different disorders. Additionally, the tractability of Drosophila simplifies genetic screens to aid in identifying novel therapeutic targets that may regulate metabolism. In order to perform such a screen a simple and fast method to identify changes in the metabolic state of flies is necessary. In general, carbon dioxide production is a good indicator of substrate oxidation and energy expenditure providing information about metabolic state. In this protocol we introduce a simple method to measure CO2 output from flies. This technique can potentially aid in the identification of genetic perturbations affecting metabolic rate.

Measurement of Metabolic Rate in Drosophila using Respirometry

Metabolic disorders are among one of the most common diseases in humans. The genetically tractable model organism D. melanogaster can be used to identify novel genes that regulate metabolism. This paper describes a relatively simple method which allows studying the metabolic rate in flies by measuring their CO2 production.