This work was supported by the National Institutes of HealthGrants DK85035 and DK074797 (I.H).

1. Worm Strains
<ol>
	<li>Obtain C. elegans wildtype Bristol N2 strains from the Caenorhabditis Genetics Center (CGC) (http://www.cbs.umn.edu/cgc) and maintain them on NGM plates seeded with E. coli strain OP507. Note: Transgenic worm strains IQ6011 (Phrg-1::GFP) utilized were generated as previously described11. IQ6011 can be requested from the corresponding author.</li>
</ol>
2. Preparation of Modified C. elegans</em...

<ol>
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The authors declare there are no competing financial interests or conflict of interests.

In this protocol we present a modified axenic liquid media mCeHR that allows for rapid C. elegans generation with production of a large number of worms. This media shows several advantages as the worms are grown without contaminating E. coli or bacterial byproducts and can be exploited in nutritional and toxicological studies. The use of E. coli or other bacteria in such studies has several drawbacks. For example, the growth of the bacteria can change under various conditions and the bacteria m...

The soil nematode, Caenorhabditis elegans, is a powerful model organism used in numerous studies from genetics to toxicology. As a result of its 1 mm size, rapid generation time of four days, ease of cultivation, and large progeny numbers, these nematodes have been utilized in a number of genetic and pharmacological screens1,2. Researchers take advantage of this worm to identify molecules and pathways conserved in vertebrate systems. These pathways include cell death signals, pathways of aging and metabolism, and the nervous system3-6. Additionally, the transparency of C. elegans allows for the generation of transgenic lines using fluorescent protein reporters, which can be directly visualized to analyze gene expression patterns and protein localization.
In many studies this nematode is cultured on a solid agar-based surface using nematode growth medium (NGM) plates or in liquid cultures seeded with Escherichia coli as a food source7,8. These bacterial food sources can confound biochemical and toxicology studies with interference from bacterial by-products affecting the interpretation of results. In order to avoid these compounding effects, C. elegans can be cultured in an axenic liquid media that is devoid of bacteria as a food source. Using this media, we successfully cultured millions of highly synchronized worms for many standard C. elegans protocols including microarray analysis of differentially regulated genes in C. elegans exposed to different heme concentrations, and production of transgenic worms using gene bombardment. This media is chemically defined and modified from an original recipe formulated by Dr. Eric Clegg9. Using this mCeHR media, we have successfully identified genes involved in heme homeostasis, referred to as heme responsive genes (hrgs)10, which would have not been possible in regular growth conditions which utilize NGM agar plates seeded with E. coli.
In this protocol we describe the procedure for introducing and maintaining C. elegans grown on E. coli to the axenic mCeHR and utilize this method to obtain a large number of worms for producing transgenic C. elegans lines using microparticle bombardment. We also present studies that show the utility of using axenic media for determining the nutritional requirement of C. elegans using heme as an example. These studies show that using mCeHR media allows for rapid growth of a large number of C. elegans for many downstream applications utilized by worm researchers.

<table border="0" cellpadding="0" cellspacing="0" width="754">
	<tbody>
		<tr height="25">
			<td height="25" style="height:25px;width:359px;">MgCl2.6H2O</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">M-2393</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium citrate</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">S-4641</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium citrate.H2O</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">P-1722</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">CuCl2.2H2O</td>
			<td style="width:108px;">Fisher</td>
			<td style="width:121px;">C455-500</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">MnCl2.4H2O</td>
			<td style="width:108px;">Fisher</td>
			<td style="width:121px;">M87-100</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">ZnCl2</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">Z-0152</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Fe(NH4)2(SO4)2.6H2O</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">F-1018</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">CaCl2.2H2O</td>
			<td style="width:108px;">Fisher</td>
			<td style="width:121px;">C70-500</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Adenosine 5 -monophosphate, sodium salt</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">A-1752</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cytidine 5 -phosphate</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">C-1006</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Guanosine 2 - and3&#160; -monophosphate</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">G-8002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Uridine 5 -phosphate, disodium salt</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">U-6375</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thymine&#160;</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">T0376</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">N-Acetylglucosamine</td>
			<td style="width:108px;">Sigma</td>
			<td>A3286</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">DL-Alanine</td>
			<td style="width:108px;">Fisher</td>
			<td>S25648&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">p-Aminobenzoic Acid</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">A-9878</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Biotin</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">B-4639</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Cyanocobalamine (B-12)</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">V-2876</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Folinate (Ca)&#160;</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">F-7878</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Niacin</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">N-0761</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Niacinamide</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">N-3376</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Pantetheine</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">P-2125</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Pantothenate (Ca)</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">P-6292</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Pteroylglutamic Acid (Folic Acid)</td>
			<td style="width:108px;">ACRCS</td>
			<td style="width:121px;">21663-0100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Pyridoxal 5&#39;-phosphate</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">P-3657</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Pyridoxamine.2HCl</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">P-9158</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Pyridoxine.HCl</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">P-6280</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:359px;">Riboflavin 5-PO4(Na)</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">R-7774</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Thiamine.HCl</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">T-1270</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">DL-6,8-Thioctic Acid</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">T-1395</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:359px;">KH2PO4</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">P-5379</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Choline di-acid citrate</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">C-2004</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">myo-Inositol</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">I-5125</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">D-Glucose</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">G-7520</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lactalbumin enzymatic hydrolysate</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">L-9010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Brain Heart Infusion</td>
			<td style="width:108px;">BD</td>
			<td style="width:121px;">211065</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:359px;">Hemin chloride</td>
			<td style="width:108px;">Frontier Scientific</td>
			<td style="width:121px;">H651-9</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">HEPES, Na salt</td>
			<td style="width:108px;">Sigma</td>
			<td style="width:121px;">H-3784</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Cholesterol</td>
			<td style="width:108px;">J.T. Baker</td>
			<td style="width:121px;">F676-05</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MEM Non-Essential Amino Acids</td>
			<td style="width:108px;">Invitrogen</td>
			<td>11140-076</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MEM Amino Acids Solution</td>
			<td style="width:108px;">Invitrogen</td>
			<td>11130-051</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nalidixic acid sodium salt</td>
			<td style="width:108px;">Sigma</td>
			<td>N4382</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tetracycline Hydrochloride</td>
			<td style="width:108px;">MP Biomedicals</td>
			<td>2194542</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Biolistic Delivery System</td>
			<td style="width:108px;">BioRad</td>
			<td>165-2257</td>
			<td></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;">Gold particles (Au Powder)&#160;</td>
			<td style="width:108px;">&#160;Ferro Electronic Material Systems</td>
			<td style="width:121px;">6420 2504, JZP01010KM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">or</td>
			<td style="width:108px;"></td>
			<td style="width:121px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gold Particles 1.0 &#956;m</td>
			<td style="width:108px;">BioRad</td>
			<td>&#160;165-2263</td>
			<td></td>
		</tr>
	</tbody>
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culturing caenorhabditis elegans in axenic liquid media and creation of transgenic worms by microparticle bombardment

In this protocol, we present the required materials, and the procedure for making modified&#160;C. elegans&#160;Habituation and Reproduction media (mCeHR). Additionally, the steps for exposing and acclimatizing C. elegans grown on E. coli to axenic liquid media are described. Finally, downstream experiments that utilize axenic C. elegans illustrate the benefits of this procedure. The ability to analyze and determine C. elegans&#160;nutrient requirement was illustrated by growing N2 wild type worms in axenic liquid media with varying heme concentrations. This procedure can be replicated with other nutrients to determine the optimal concentration for worm growth and development or, to determine the toxicological effects of drug treatments. The effects of varied heme concentrations on the growth of wild type worms were determined through qualitative microscopic observation and by quantitating the number of worms that grew in each heme concentration. In addition, the effect of varied nutrient concentrations can be assayed by utilizing worms that express fluorescent sensors that respond to changes in the nutrient of interest. Furthermore, a large number of worms were easily produced for the generation of transgenic C. elegans using microparticle bombardment.

Culturing C. elegans in axenic liquid medium aids in the determination of nutrients that are required by worms, without interference from secondary metabolites produced by E. coli. Wildtype N2 worms acclimatize to mCeHR media within three generations and show growth comparable to worms grown on NGM bacterial plates. Indeed, these worms become gravid within 4&#160;days as compared with 3.5 days for worms grown on OP50 bacteria.
One advantage of using mCeHR was seen in studies ...

Watch this Scientific Journal Video about Culturing Caenorhabditis elegans in Axenic Liquid Media and Creation of Transgenic Worms by Microparticle Bombardment at JoVE.com

Culturing Caenorhabditis elegans in Axenic Liquid Media and Creation of Transgenic Worms by Microparticle Bombardment

C. elegans is usually grown on solid agar plates or in liquid cultures seeded with E. coli. To prevent bacterial byproducts from confounding toxicological and nutritional studies, we utilized an axenic liquid medium, CeHR, to grow and synchronize a large number of worms for a range of downstream applications.

Culturing Caenorhabditis elegans in Axenic Liquid Media and Creation of Transgenic Worms by Microparticle Bombardment

In this protocol, we present the required materials, and the procedure for making modified&#160;C. elegans&#160;Habituation and Reproduction media ...

culturing-caenorhabditis-elegans-axenic-liquid-media-creation

Research

JoVE Journal

Biology

16.8K Views.  University of Maryland. C. elegans is usually grown on solid agar plates or in liquid cultures seeded with E. coli. To prevent bacterial byproducts from confounding toxicological and nutritional studies, we utilized an axenic liquid medium, CeHR, to grow and synchronize a large number of worms for a range of downstream applications.