Name: using rna-mediated interference feeding strategy to screen for genes involved in body size regulation in the nematode c. elegans
Uploaded: 2013-02-13T12:00:00
Description: Watch this Scientific Journal Video about Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans at JoVE.com

We thank James Clark for providing figures of animals at various developmental time points. C. elegans strains in this study were obtained from the Caenorhabditis Genetics Center, which is supported by the NIH National Center for Research Resources (NCRR). This work was supported by CIRG 1817 from CUNY to J.L. and C.S.D.; and by NIH 1R15GM073678-01 and 1R15GM097692-01 to C.S.D. We thank Dr. William J Rice, Dr. Nathalia Holtzman, and Melissa Silvestrini for comments on the manuscript. This work was carried out in partial fulfillment of the requirements for a PhD degree from the Graduate Center of the City University of New York (S. Xiong).

1. Preparing RNAi Feeding Plates Carrying Target Gene Sequence
<ol>
	<li>If using commercially available RNAi libraries (e.g. from Source BioScience LifeSciences), proceed to step 1.4. Alternatively, clone target gene sequences into vector L4440, a commonly used worm RNAi plasmid8, by standard cloning protocol.</li>
	<li>Transform the recombinant plasmid into bacterial strain HT115(DE3), culture them on LB agar plates with 25 &mu;g/ml carbenicillin and 12.5 &mu;g/ml tetracycline, and pick a single c...

<ol>
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In this protocol, we describe our method for the identification of body size defective mutants of C. elegans by RNAi feeding. This method is applicable to the identification of TGF-&beta; signaling components. Since such components are highly conserved through evolution15, such screens are relevant to elucidating the molecular mechanisms of TGF-&beta; signaling in all metazoans. An important consideration in designing such a screen is the starting strain. We have demonstrated that both eri-1;lin-1...

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 <td>RNAi worm plates 
 17.7 g Worm Medium Mix 
 60 g Agar 
 Add H2O to 3 liters. Autoclave. 
 Add 3 ml 1M IPTG(sterile) and 3 ml 25 mg/ml Carbenicillin(sterile); then pour into 60 mm Petri dishes. 
 
 Worm plates 
 17.7 g Worm Medium Mix 
 0.6 g Streptomycin Sulfate 
 60 g Agar 
 Add H2O to 3 liters. Autoclave. Pour into 60 mm Petri dishes. 
 
 Worm Medium Mix 
 55 g Tris-Cl 
 24 g Tris-OH 
 310 g Bacto Peptone 
 800 mg Cholesterol 
 200 g NaCl 
Mix thoroughly and be sure to avoid chunks; this powdered mixture can be stored for many months prior to use. 
2% agarose 
0.5 g Agarose 
Add 25 ml dH2O. Heat in microwave until dissolved. 
 
1M Isopropyl &beta;-D-1-thiogalactopyranoside (IPTG) 
2 g IPTG 
Dissolve in10 ml dH2O 
 
1M NaN3 
6.5 g NaN3 
Add dH2O to 100 ml 
 
25 mM NaN3 
2.5 ml 1M NaN3 
Add dH2O to 100 ml 
 
Caenorhabditis elegans from Caenorhabditis Genetics Center 
L4440 plasmid (carries ampicillin-resistance gene) 
Bacteria strain HT115 (DE3) (contains IPTG inducible T7 polymerase; deficient for RNAse III gene (a dsRNAse) which also carries tetracycline-resistance gene)16 
60 mm Petri dishes 
100 mm Petri dishes 
14 ml round-bottom Falcon culture tubes 
glass slides 
glass coverslips 
1-20 &mu;l pipettor 
20-200 &mu;l pipettor 
200-1000 &mu;l pipettor 
1-200 &mu;l pipet tips 
200-1000 &mu;l pipet tips 
1.5 ml Eppendorf tubes 
platinum wire worm pick
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using rna-mediated interference feeding strategy to screen for genes involved in body size regulation in the nematode c. elegans

Double-strand RNA-mediated interference (RNAi) is an effective strategy to knock down target gene expression1-3. It has been applied to many model systems including plants, invertebrates and vertebrates. There are various methods to achieve RNAi in vivo4,5. For example, the target gene may be transformed into an RNAi vector, and then either permanently or transiently transformed into cell lines or primary cells to achieve gene knockdown effects; alternatively synthesized double-strand oligonucleotides from specific target genes (RNAi oligos) may be transiently transformed into cell lines or primary cells to silence target genes; or synthesized double-strand RNA molecules may be microinjected into an organism. Since the nematode C. elegans uses bacteria as a food source, feeding the animals with bacteria expressing double-strand RNA against target genes provides a viable strategy6. Here we present an RNAi feeding method to score body size phenotype. Body size in C. elegans is regulated primarily by the TGF- &beta; - like ligand DBL-1, so this assay is appropriate for identification of TGF-&beta; signaling components7. We used different strains including two RNAi hypersensitive strains to repeat the RNAi feeding experiments. Our results showed that rrf-3 strain gave us the best expected RNAi phenotype. The method is easy to perform, reproducible, and easily quantified. Furthermore, our protocol minimizes the use of specialized equipment, so it is suitable for smaller laboratories or those at predominantly undergraduate institutions.

In our research, we focus on body size regulation by the DBL-1/TGF-&beta; pathway. The loss of function of the DBL-1 pathway results in small body size, including a shorter body length compared with wild-type animals7,10,11. Thus, screens for C. elegans body size mutants are capable of identifying TGF-&beta; signaling components and modifiers. DBL-1 signaling is mediated by a conserved TGF-&beta; signal transduction pathway that includes cell surface receptors and intracellular Smad signal transducers...

Watch this Scientific Journal Video about Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans at JoVE.com

Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans

We demonstrate how to use the RNAi feeding technique to knock down target genes and score body size phenotype in C. elegans. This method could be used for a large scale screen to identify potential genetic components of interest, such as those involved in body size regulation by DBL-1/TGF-&beta; signaling.

Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans

Double-strand RNA-mediated interference (RNAi) is an effective strategy to knock down target gene expression1-3. It has been applied to many model systems ...

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