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 Habitation and Reproduction Medium (mCeHR)
Prepare mCeHR liquid media as described below12. This axenic liquid media allows the worms to grow without any additional food sources. Carry out all manipulations of axenic liquid media and axenic worms using strictly sterile conditions such as a laminar flow hood.
<ol>
	<li>Obtain ultra pasteurized fat-free milk from a grocery store. Use the refrigerated product and not the room temperature product. Prior to use in mCeHR medium, streak the milk on Brain Heart Infusion (BHI) agar plates and incubate for 3 days at 30 &#176;C and 37 &#176;C to check for sterility. Transfer the milk to 50 ml sterile tubes and store at -80 &#176;C</li>
	<li>Prepare each of the following components and combine in the order and amounts given to prepare 1 L&#160;of mCeHR (Table 1A): 10 ml of 2 mM choline diacid citrate, 10 ml of vitamin and growth factor mix (see recipe in Table 1B), 10 ml of 2.4 mM myo-inositol, 10 ml of 2 mM hemin chloride, 250 ml of deionized water. Apply suction and filter through a 0.22 &#956;m filter unit.</li>
	<li>Add 20 ml of nucleic acid mix (recipe in Table 1C), 100 ml of mineral mix (recipe in Table 1D), 20 ml of 170 mg/ml lactalbumin hydrolysate, 20 ml of essential amino acids, 10 ml of non-essential amino acids, 20 ml of 450 mM KH2PO4, 50 ml of 1.45 M D-glucose, 10 ml of 1 M HEPES, sodium&#160;salt, 250 ml deionized water.</li>
	<li>Apply suction to filter sterilize the components. Remove the filter and add 1 ml of 5 mg/ml cholesterol. Ensure that the pH of the media is approximately 6-6.5. Note: This solution can be stored at -80 &#176;C for up to one year.</li>
	<li>Add 20% (v/v) ultra pasteurized organic skim milk to the mCeHR medium before use. Use scrupulously sterile technique (for example in a laminar flow hood) when opening and aliquoting the milk. Store the media at 4 &#176;C.</li>
</ol>
3. Prepare C. elegans for Culture in Axenic mCeHR Liquid Medium
<ol>
	<li>Grow worms on ten 60&#160;mm NGM plates until there are many gravid worms and a minimal amount of OP50 E. coli on the plates.</li>
	<li>Remove the worms from each plate by rinsing with 5 ml of M9 buffer (recipe in Table 1F), and combine in a 50 ml conical tube.</li>
	<li>Allow the worms to settle by leaving the tube to stand for 5 to 10 min&#160;then carefully remove the supernatant containing the E. coli.</li>
	<li>Repeat steps 3.2 and 3.3 2x to remove as much of the residual bacteria as possible before continuing the procedure.</li>
	<li>Resuspend the worms in 0.1 N NaCl in a volume that is a multiple of three, for example 1.5 ml, 3 ml or 6 ml in which individual worms can be seen in the tube.</li>
	<li>Bleach the worms by adding 5 N NaOH and 5% sodium hypochlorite (bleach) solution in a 1:2:6 ratio to the worm suspension. For example, 1 ml 5 N NaOH: 2 ml 5% sodium hypochlorite: 6 ml of the worm suspension. Mix the NaOH and bleach before adding to the worm suspension.</li>
	<li>Vortex the solution vigorously until the gravid worms are dissolved and only eggs are visible within the suspension (about 5 to 10 min). Monitor the process using a phase contrast microscope with a 10X objective.</li>
	<li>After the worms have completely dissolved, immediately pellet the eggs at 800 x g for 45 sec at 4 &#176;C. Remove the supernatant and rinse the pellet twice with 10 ml of sterile water by centrifuging the pellet at 800 x g for 45 sec at 4 &#176;C.</li>
	<li>After bleaching, transfer the egg pellet to a 25 cm2 tissue culture flask containing 10 ml of mCeHR media supplemented with 100 &#956;g/ml tetracycline. Carry out this procedure using sterile techniques. If desired, add additional antibiotics, including 250 &#956;g/ml nalidixic acid, to prevent bacterial growth in the axenic liquid cultures.</li>
	<li>Incubate the liquid cultures at 20 &#176;C on a shaking incubator at approximately 70 rpm.</li>
	<li>Check the worms daily to note the stage of development and the rate of growth. 
	Note: Worms will initially grow slowly and require 7 to 10 days to become gravid. However, as the worms acclimatize to the liquid medium the generation time will decrease to approximately 4 days for wildtype (N2) worms.</li>
	<li>After the worms have developed to the gravid stage in liquid media, transfer the worm culture to a conical tube and pellet the worms at 800 x g for 5 min&#160;at 4 &#176;C using a swinging bucket rotor.</li>
	<li>Remove the supernatant and gently resuspend the worm pellet in an equal volume of 0.1 M NaCl. For example, use 10 ml of 0.1 M NaCl for worms cultured in 10 ml of mCeHR. Allow the worms to settle for 5 min&#160;on ice.</li>
	<li>Carry out the bleaching procedure as described above in steps 3.5-3.8, and allow the worms to grow for a second generation in the axenic liquid media. If necessary, add the antibiotic again to inhibit bacterial growth.</li>
	<li>Again allow the worms to become gravid then pellet and resuspend the worms in 0.1 M NaCl as described in steps 3.12 and 3.13, then bleach again as described in steps 3.5-3.8, to produce a synchronized population. Grow the L1 larval worms in liquid media without antibiotics from now on.</li>
</ol>
4. Synchronizing Worms from Liquid Culture
<ol>
	<li>Pellet and resuspend the worms in 0.1 M NaCl as described above in steps 3.12 and 3.13. Bleach as described above in steps 3.5-3.8.</li>
	<li>Resuspend the egg pellet in 10 ml of M9 buffer and allow the larvae to hatch O/N at 20 &#176;C on a rotating platform shaker. Note: The eggs will hatch into L1 larvae, but will not develop further, synchronizing the worms at the L1 stage.</li>
	<li>To maintain and subculture worms, pellet L1 larvae at 800 x g for 5 min, then resuspend the larvae in 10 ml of mCeHR and transfer to a 25 cm2 flask. Allow the worms to grow at 20 &#176;C on a rotating platform. Maintain a maximum density of 3,000 worms/ml/cm2 to ensure adequate nutrition for the worms. 
	Note: At this stage, antibiotics are not required to maintain axenic conditions when the procedures are carried out using sterile techniques in a laminar flow hood. Worms should be checked daily to monitor growth.</li>
</ol>
5. Freezing and Thawing Worms for Axenic Medium Cultures
<ol>
	<li>Freeze axenic asynchronous worm cultures or synchronized L1 larvae in liquid nitrogen. Pellet worms at 800 x g for 5 min then resuspend in S buffer (6.45 mM KHPO4, 43.55 mM KHPO4, 146.25 mM NaCl) using 0.5 ml for each vial. Add an equal volume of S buffer with 30% v/v glycerol to each vial and transfer the worms to -80 &#176;C before long term storage in liquid N2. Freeze approximately 1 x 106 worms per ml in each vial.</li>
	<li>Thaw worms by incubating the vials at 37 &#176;C for approximately 2 min until almost all of the ice is melted. In a laminar flow hood, transfer the worms to a sterile flask containing mCeHR and place them at 20 &#176;C.</li>
</ol>
6. Determine the Effect of Hemin Concentration on Growth and Reproduction in mCeHR
<ol>
	<li>Use axenic mCeHR media to assay nutrient dependent growth of C. elegans. To determine the effect of hemin concentration on worm growth and development, use synchronized axenic N2 worms or other strains of interest. Synchronize L1 larvae as described above in section 4.</li>
	<li>On the following day, pellet and count synchronized L1 larvae and dilute to 1 worm per &#956;l of axenic media. Make 10 mM hemin chloride in 0.3 M NH4OH and adjust to pH 8 using concentrated HCl.</li>
	<li>Add 800 &#956;l of mCeHR media to a 24-well plate. Add 100 worms to each well in 100 &#956;l of media. Add hemin chloride to each well in concentrations ranging from 0 &#956;M, 1.5 &#956;M to 1,000 &#956;M in triplicate. Ensure that all wells contain the same concentration of 0.3 M NH4OH. Gently resuspended the worms before pipetting to ensure that 100 L1 larvae are added to each well.</li>
	<li>Examine the worms daily and note the growth in each concentration in each well. Count the number of worms after 9 days of incubation and plot the number of worms/ml corresponding to each heme concentration (Figure 1).</li>
</ol>
7. Effect of Hemin Concentration on Heme Sensor Worms
<ol>
	<li>Incubate synchronized L1 heme sensor worms (Phrg-1::gfp) in mCeHR containing 4 &#956;M, 8 &#956;M, 10 &#956;M and 20 &#956;M hemin.</li>
	<li>Image the worms using fluorescence confocal microscopy, 48 hr&#160;post incubation (Figure 2).</li>
</ol>
8. Utilizing mCeHR to Generate Transgenic C. elegans&#160;Using Microparticle Bombardment
Note: The procedure for generating and carrying out microparticle bombardment using unc-119(ed3) worms grown in mCeHR is outlined in Figure 313.
<ol>
	<li>Worm Preparation
	<ol>
		<li>Transfer approximately 1 x 106 asynchronous unc-119(ed3) worms in 90 ml of mCeHR media in a 175 cm2 flask one week prior to bombardment. Allow the worms to grow at 20 &#176;C on a shaking platform at ~70 rpm (Figure 3-1). 
		Note: One week later, the worm density should be significantly greater with many adult gravid worms. Approximately 3 x 107 worms will be required for microparticle bombardment.</li>
		<li>Chill JM109 E. coli seeded 10 cm NGM plates on ice.</li>
		<li>Transfer the axenic worms to two 50 ml conical tubes and centrifuge the worms at 800 x g for 2 min. Aspirate the supernatant and resuspend the worms in each tube in 50 ml of M9 buffer (Figure 3-2).</li>
		<li>Allow the adult worms to pellet by gravity for 10 to 15 min&#160;on ice. 
		Note: The 2 ml pellet should now contain &#62;90% adult worms. This 2 ml pellet should have approximately 5 x 106 worms and is sufficient for one microparticle bombardment.</li>
		<li>Coat the entire surface of the chilled JM109 seeded NGM plate with the 2 ml pellet of worms. Allow the liquid to be completely absorbed then leave the plate for 30 min&#160;on ice before proceeding (Figure 3-3).</li>
	</ol>
	</li>
	<li>Preparation of gold particles
	<ol>
		<li>Weigh 30 mg of gold particles into a siliconized microcentrifuge tube. Add 1 ml 70% ethanol and vortex the tube for 5 min.</li>
		<li>Allow the tube to sit for 15 min, then centrifuge at 6,000 x g for 10 sec to pellet the gold particles. Remove the supernatant using a pipette tip by carefully touching the tip to the side of the tube opposite to the gold particles.</li>
		<li>Wash the gold particles with 1 ml of sterile water, vortex for 1 min&#160;and briefly centrifuge the tube at 6,000 x g for 10 sec. Repeat the wash step twice, then resuspend the gold particles in 0.5 ml of sterile 50% glycerol. 
		Note: The final concentration of the gold particles will be 60 mg/ml and it can be stored for 1 to 2 months at 4 &#176;C.</li>
	</ol>
	</li>
	<li>Prepare the DNA-gold particle mix
	<ol>
		<li>Combine 10 &#956;g of the desired plasmid DNA with 10 &#956;g of the unc-119 rescue plasmid in a siliconized 1.5 ml microcentrifuge tube. Add 50 &#956;l of DI water and 100 &#956;l of well resuspended gold particle solution then vortex for 1 min.</li>
		<li>Add 150 &#956;l of 2.5 M CaCl2 and vortex the solution again for 1 min. To this solution, add 60 &#956;l of 0.1 M spermidine and vortex for 3 to 5 min.</li>
		<li>Pulse centrifuge the solution at 6,000 x g for 10 sec, remove the supernatant and add 300 &#956;l of 70% ethanol. Vortex well for 1&#160;min, pulse centrifuge at 6,000 x g, remove the supernatant and resuspend in 170 &#956;l of 100% ethanol. Vigorously vortex the solution for 5 to 10 min&#160;then pulse centrifuge and remove the supernatant.</li>
	</ol>
	</li>
	<li>Bombardment (Figure 3-3) 
	Note: This protocol is carried out with the particle delivery system specified in the Table of Materials/Equipment. Follow the instructions for the particle delivery instrument available.
	<ol>
		<li>Place a sheet of tissue paper into a 15 cm plate. Using tweezers, dip seven macrocarriers individually into 100% ethanol and lay them on the tissue to dry.</li>
		<li>Thoroughly clean the biolistic chamber, macrocarrier holder, and target plate with 70% ethanol. Clean and autoclave the stopping screens before each bombardment procedure.</li>
		<li>Load the macrocarrriers into the holder using tweezers and press into the holder using the seating tool.</li>
		<li>Evenly spread 20 &#956;l of the DNA coated gold particles in the center of each macrocarrier and then allow the solution to dry completely.</li>
		<li>Clean the two parts of the pressure divider with ethanol and assemble with ethanol cleaned rupture disks. Screw the assembled pressure divider and rupture disks into the bombardment chamber.</li>
		<li>Assemble an autoclaved stopping screen with the macrocarrier holder and place the apparatus on to the metal shelf required and lock in place.</li>
		<li>Insert the assembled macrocarrier apparatus into the biolistic chamber in the allotted slot below the pressure divider and align with the pressure divider.</li>
		<li>Tape the open NGM plate with the worms onto the target plate shelf and close the door of the chamber.</li>
		<li>To bombard worms, adjust the pressure to that needed to break the rupture disks. Turn on the vacuum to 28 inches of Hg pressure, then press the fire button until the disks rupture.</li>
		<li>Release the vacuum and remove the NGM plate from the apparatus. Wash the worms from the plate and redistribute in twenty 10 cm NGM plates seeded with JM109 E. coli (Figure 3-4).</li>
		<li>Allow the worms to grow for 10 to 14 days at 25 &#176;C and starve the plates. Worms rescued from the unc-119 defect will have normal movement and can be identified at this time. Pick at least 10 &#8220;wildtype&#8221; worms from separate plates for further analysis as these represent independent transgenic lines (Figure 3-5).</li>
	</ol>
	</li>
</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 may metabolize molecules that are being assayed, confounding the interpretation of results. Therefore, the development of a defined medium to perform these studies is highly advantageous.
Although C. elegans have been grown in liquid media in previous studies15, worms grown in the C. elegans maintenance medium (CeMM) show a distinct delay in generation times16, unlike what we observe in mCeHR medium. Our main goal was to exploit C. elegans to study nutrient homeostasis with specific emphasis on heme and metal metabolism. With this in mind, mCeHR and modifications generated by our group accomplish this goal and has directly led to the identification of a number of genes required for maintaining heme homeostasis in the worm and ultimately in vertebrate model systems17,18. Reformulated mCeHR-1 media can also be exploited for other nematode species including Panagrellus redivivus, Oscheius myriophila, and C. remanei. In addition low metal formulations mCeHR-2 and mCeHR-3 can be exploited in studies examining heavy metal toxicity and requirements12.
Prior to acclimatization, N2 worms exhibit a longer generation time of approximately 7 to 10 days in mCeHR media. As the worms are subcultured, this generation time decreases to 4 days, similar to that of worms grown on OP50 bacteria. However, the generation time may be longer for certain mutant worms, plausibly because of defects in feeding, movement, or specific nutritional requirements.
When using axenic liquid media it is critical that fastidious sterile techniques are utilized. Usually, the use of antibiotics is minimized and eventually eliminated as the worms acclimatize to the medium and the residual bacteria are eliminated. Antibiotics are initially required to ensure that the cultures are axenic when established as it prevents the growth of residual bacteria that can overwhelm the worm cultures. After two successive rounds of bleaching, antibiotics are omitted from the cultures as continual usage of antibiotics only masks poor aseptic techniques that are essential for growing worms axenically. Using these techniques in a laminar flow cabinet, the authors have been able to grow the worms axenically without contamination. Additionally, proper storage of the media and components is essential for worm maintenance and growth. The worms should be checked for the rate of growth and subcultured to prevent crowding, which can lead to dauer formation as essential nutrients are depleted. This can be prevented by ensuring that the density of worms does not exceed 3,000 worms/ml/cm2. Researchers that are new to growing C. elegans axenically can achieve this by checking the worms daily and counting the worms weekly.
C. elegans researchers take advantage of its transparent properties by generating transgenic worms expressing fluorescently-tagged markers that allow for visualization of gene expression and protein localization. Utilizing biolistic bombardment allowed for generation of low copy integrants that avoided the issues of extrachromosomal arrays and elevated gene expression noted with transgenics generated using injection19. Previously, one drawback of generating transgenics using microparticle bombardment of C. elegans was the requirement for egg plate preparation to generate the large number of unc-119 (ed3) worms necessary for the procedure20. Each transformation required 20 egg plates for the number of worms needed. Using axenic mCeHR liquid culture allows more efficient growth and subsequently more worms for bombardments. Additionally, bombardments can be used in conjunction with drug selection to avoid using unc-119 (ed3) worms21.

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><tbody><tr><td>MgCl&lt;sub&gt;2&lt;/sub&gt;&amp;#8226;6H2O</td><td>Sigma</td><td>M-2393</td><td></td></tr><tr><td>Sodium citrate</td><td>Sigma</td><td>S-4641</td><td></td></tr><tr><td>Potassium citrate monohydrate</td><td>Sigma</td><td>P-1722</td><td></td></tr><tr><td>CuCl&lt;sub&gt;2&lt;/sub&gt;&amp;#8226;2H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Fisher</td><td>C455-500</td><td></td></tr><tr><td>MnCl&lt;sub&gt;2&lt;/sub&gt;&amp;#8226;4H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Fisher</td><td>M87-100</td><td></td></tr><tr><td>ZnCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma</td><td>Z-0152</td><td></td></tr><tr><td>Fe(NH4)&lt;sub&gt;2&lt;/sub&gt;(SO4)&lt;sub&gt;2&lt;/sub&gt;&amp;#8226;6H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma</td><td>F-1018</td><td></td></tr><tr><td>CaCl&lt;sub&gt;2&lt;/sub&gt;&amp;#8226;2H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Fisher</td><td>C70-500</td><td></td></tr><tr><td>Adenosine 5 -monophosphate, sodium salt</td><td>Sigma</td><td>A-1752</td><td></td></tr><tr><td>Cytidine 5 -phosphate</td><td>Sigma</td><td>C-1006</td><td></td></tr><tr><td>Guanosine 2&#039; - and 3&#039; -monophosphate</td><td>Sigma</td><td>G-8002</td><td></td></tr><tr><td>Uridine 5 -phosphate, disodium salt</td><td>Sigma</td><td>U-6375</td><td></td></tr><tr><td>Thymine</td><td>Sigma</td><td>T0376</td><td></td></tr><tr><td>N-Acetylglucosamine</td><td>Sigma</td><td>A3286</td><td></td></tr><tr><td>DL-Alanine</td><td>Fisher</td><td>S25648&amp;nbsp;</td><td></td></tr><tr><td>p-Aminobenzoic Acid</td><td>Sigma</td><td>A-9878</td><td></td></tr><tr><td>Biotin</td><td>Sigma</td><td>B-4639</td><td></td></tr><tr><td>Cyanocobalamine (B-12)</td><td>Sigma</td><td>V-2876</td><td></td></tr><tr><td>Folinate (Ca)</td><td>Sigma</td><td>F-7878</td><td></td></tr><tr><td>Niacin</td><td>Sigma</td><td>N-0761</td><td></td></tr><tr><td>Niacinamide</td><td>Sigma</td><td>N-3376</td><td></td></tr><tr><td>Pantetheine</td><td>Sigma</td><td>P-2125</td><td></td></tr><tr><td>Pantothenate (Ca)</td><td>Sigma</td><td>P-6292</td><td></td></tr><tr><td>Pteroylglutamic Acid (Folic Acid)</td><td>ACRCS</td><td>21663-0100</td><td></td></tr><tr><td>Pyridoxal 5&#039;-phosphate</td><td>Sigma</td><td>P-3657</td><td></td></tr><tr><td>Pyridoxamine 2HCl</td><td>Sigma</td><td>P-9158</td><td></td></tr><tr><td>Pyridoxine HCl</td><td>Sigma</td><td>P-6280</td><td></td></tr><tr><td>Riboflavin 5-PO&lt;sub&gt;4&lt;/sub&gt;(Na)</td><td>Sigma</td><td>R-7774</td><td></td></tr><tr><td>Thiamine HCl</td><td>Sigma</td><td>T-1270</td><td></td></tr><tr><td>DL-6,8-Thioctic Acid</td><td>Sigma</td><td>T-1395</td><td></td></tr><tr><td>KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma</td><td>P-5379</td><td></td></tr><tr><td>Choline di-acid citrate</td><td>Sigma</td><td>C-2004</td><td></td></tr><tr><td>&lt;em&gt;myo&lt;/em&gt;-Inositol</td><td>Sigma</td><td>I-5125</td><td></td></tr><tr><td>D-Glucose</td><td>Sigma</td><td>G-7520</td><td></td></tr><tr><td>Lactalbumin enzymatic hydrolysate</td><td>Sigma</td><td>L-9010</td><td></td></tr><tr><td>Brain Heart Infusion</td><td>BD</td><td>211065</td><td></td></tr><tr><td>Hemin chloride</td><td>Frontier Scientific</td><td>H651-9</td><td></td></tr><tr><td>HEPES, sodium salt</td><td>Sigma</td><td>H-3784</td><td></td></tr><tr><td>Cholesterol</td><td>J.T. Baker</td><td>F676-05</td><td></td></tr><tr><td>MEM Non-Essential Amino Acids</td><td>Invitrogen</td><td>11140-076</td><td></td></tr><tr><td>MEM Amino Acids Solution</td><td>Invitrogen</td><td>11130-051</td><td></td></tr><tr><td>Nalidixic acid sodium salt</td><td>Sigma</td><td>N4382</td><td></td></tr><tr><td>Tetracycline Hydrochloride</td><td>MP Biomedicals</td><td>2194542</td><td></td></tr><tr><td>Biolistic Delivery System</td><td>BioRad</td><td>165-2257</td><td></td></tr><tr><td>Gold particles (Au Powder)&amp;nbsp;</td><td>&amp;nbsp;Ferro Electronic Material Systems</td><td>6420 2504, JZP01010KM</td><td></td></tr><tr><td>or</td><td></td><td></td><td></td></tr><tr><td>Gold Particles 1.0 &amp;mu;m</td><td>BioRad</td><td>&amp;nbsp;165-2263</td><td></td></tr></tbody></table>

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 that examined the exact nutrient requirement of these worms14. In Figure 1 worms were grown in mCeHR supplemented with increasing amounts of heme,&#160;up to 1 mM. Observations of these worms showed a distinct delay in growth at heme concentrations below 4 &#956;M, with worms developing to the L4 larval stage but unable to progress to the gravid stage after nine days in mCeHR. At concentrations of 10 &#956;M and 20 &#956;M heme the worms develop to the gravid stage in 4 days and produce large number of progeny. A maximum number of progeny was seen when worms were grown in mCeHR containing 20 &#956;M heme. Worms continued to develop and produce progeny at 100 &#956;M and 500 &#956;M heme. However, the number of larval progeny significantly declined in comparison to worms grown at the optimal heme concentration of 20 &#956;M heme. Heme concentrations at or above 800 &#956;M resulted in stunted, sickly worms at the L3 larval stage, which indicated that these heme concentrations were toxic to the worms.
In addition to determining the optimal heme concentration and the effect of heme deprivation and heme toxicity on C. elegans growth, heme reporter strains could be utilized to indirectly assess the heme status of the worm within a smaller concentration range. The IQ6011 worm is a transgenic worm that expresses a heme responsive transcriptional reporter, Phrg-1::GFP, that inversely expresses GFP in response to environmental heme concentrations. When this worm is exposed to low environmental heme in mCeHR, GFP is highly expressed. This response is reversed under heme replete conditions, as seen in Figure 2. GFP expression is repressed at 20 &#956;M heme and increases as the heme concentration is decreased. The incremental changes in heme concentration can be accurately correlated with gene response and expression in mCeHR media.
In addition to being able to carefully control nutrient concentrations provided to the worm, mCeHR axenic media allows for the efficient growth of a large number of synchronized worms. &#160;This feature can be exploited for microparticle bombardment (Figure 3). Using this procedure at least one integrated line have been developed from every microparticle bombardment carried out (Table 2).
<img alt="Figure 1" src="/files/ftp_upload/51796/51796fig1highres.jpg" /> 
Figure 1.&#160;C. elegans heme growth curve. Worms were grown in a range of heme concentrations from 0 &#956;M to 1,000 &#956;M in mCeHR for 9 days. The number of worms in each concentration was counted and plotted. At 1.5 &#956;M heme concentrations worms were L4 and unable to further develop. At 800 &#956;M heme the worms were stunted at L2-L3 stages and showed effects of heme toxicity.
<img alt="Figure 2" src="/files/ftp_upload/51796/51796fig2highres.jpg" /> 
Figure 2.&#160;Response of heme sensor (Phrg-1::GFP) strain to different heme concentrations in mCeHR. Synchronized transgenic C. elegans expressing hrg-1::GFP were grown in mCeHR media supplemented with 4, 8, 10, or 20 &#181;M heme for 48 hr.&#160; Images were taken with a Zeiss LSM 710 confocal microscope. Scale bar is 100 &#181;m. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51796/51796fig2highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/51796/51796fig3highres.jpg" /> 
Figure 3.&#160;Schematic of microparticle bombardment in C. elegans using unc-119 worms grown in mCeHR. (1) Approximately 3 x 107 unc-119(ed3) worms are grown in 90 ml mCeHR media. (2) Gravids were allowed to settle on ice for 10-15 min in 50 ml&#160;conical tubes.&#160; (3) A 2 ml&#160;pellet of approximately 5 x 106 gravid worms was spread evenly onto an unseeded NGM plate. The worms were bombarded with 12 &#956;g of plasmid of interest and 6 &#956;g of unc-119 rescue plasmid complexed to gold particles. (4) The bombarded worms were split onto twenty&#160;10 cm plates seeded with the E. coli strain JM109.&#160; (5) After 2 weeks incubation at 25 &#176;C, plates with wild type worms were selected for analysis of transgene expression strength and segregation rates.&#160;
<table border="0" cellpadding="0" cellspacing="0" width="479">
	<tbody>
		<tr>
			<td colspan="2" style="text-align:center">Table 1A</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">CeHR, 1 L</td>
		</tr>
		<tr>
			<td colspan="2">Using sterile technique and a 1 L (0.22 &#956;m) vacuum filter unit, filter the following volumes of stock solutions and water in the order described.&#160;</td>
		</tr>
		<tr>
			<td>Choline diacid citrate</td>
			<td>10 ml&#160;</td>
		</tr>
		<tr>
			<td>Vitamin and growth factor mix&#160;</td>
			<td>10 ml&#160;</td>
		</tr>
		<tr>
			<td>myo-Inositol&#160;</td>
			<td>10 ml&#160;</td>
		</tr>
		<tr>
			<td>Hemin chloride&#160;</td>
			<td>10 ml</td>
		</tr>
		<tr>
			<td>Deionized water</td>
			<td>250 ml&#160;</td>
		</tr>
		<tr>
			<td>Nucleic acid mix</td>
			<td>20 ml</td>
		</tr>
		<tr>
			<td>Mineral Mix</td>
			<td>100 ml</td>
		</tr>
		<tr>
			<td>Lactalbumin hydrolysate</td>
			<td>20 ml</td>
		</tr>
		<tr>
			<td>Essential Amino Acid Mix</td>
			<td>20 ml</td>
		</tr>
		<tr>
			<td>Non-essential Amino Acid Mix</td>
			<td>10 ml</td>
		</tr>
		<tr>
			<td>KH2PO4&#160;</td>
			<td>20 ml</td>
		</tr>
		<tr>
			<td>D-Glucose&#160;</td>
			<td>50 ml</td>
		</tr>
		<tr>
			<td>HEPES, sodium salt</td>
			<td>10 ml&#160;</td>
		</tr>
		<tr>
			<td>Deionized water</td>
			<td>250 ml</td>
		</tr>
		<tr>
			<td>Volume will be 800 ml at this point 
			Remove filter unit from vacuum then add:</td>
		</tr>
		<tr>
			<td>Cholesterol</td>
			<td>1 ml</td>
		</tr>
		<tr>
			<td>Ultra-pasteurized skim milk&#160;</td>
			<td>200 ml</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Table 1B</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Vitamin and growth factor mix, 100 ml</td>
		</tr>
		<tr>
			<td>Solution 1: To 60 ml of water add:</td>
			<td></td>
		</tr>
		<tr>
			<td>N-acetyl-&#945;-D-glucosamine&#160;</td>
			<td>0.15 g</td>
		</tr>
		<tr>
			<td>DL-alanine&#160;</td>
			<td>0.15 g</td>
		</tr>
		<tr>
			<td>Nicotinamide</td>
			<td>0.075 g</td>
		</tr>
		<tr>
			<td>D-pantethine</td>
			<td>0.0375 g&#160;</td>
		</tr>
		<tr>
			<td>DL-pantothenic acid, hemi calcium salt</td>
			<td>0.075 g</td>
		</tr>
		<tr>
			<td>Folic acid</td>
			<td>0.075 g</td>
		</tr>
		<tr>
			<td>Pyridoxamine 2HCl</td>
			<td>0.0375 g&#160;&#160;</td>
		</tr>
		<tr>
			<td>Pyridoxine HCl</td>
			<td>0.075 g&#160;</td>
		</tr>
		<tr>
			<td>Flavin mononucleotide, sodium salt</td>
			<td>0.075 g</td>
		</tr>
		<tr>
			<td>Thiamine hydrochloride</td>
			<td>0.075 g</td>
		</tr>
		<tr>
			<td>Solution 2: Prepare the following chemicals in 5 ml 1 N KOH:</td>
			<td></td>
		</tr>
		<tr>
			<td>p-aminobenzoic acid</td>
			<td>0.075 g&#160;</td>
		</tr>
		<tr>
			<td>D-biotin</td>
			<td>0.0375 g&#160;</td>
		</tr>
		<tr>
			<td>Cyanocobalamin (B12)</td>
			<td>0.0375 g&#160;</td>
		</tr>
		<tr>
			<td>Folinic acid, calcium salt</td>
			<td>0.0375 g&#160;</td>
		</tr>
		<tr>
			<td>Nicotinic acid</td>
			<td>0.075 g</td>
		</tr>
		<tr>
			<td>Pyridoxal 5-phosphate</td>
			<td>0.0375 g&#160;</td>
		</tr>
		<tr>
			<td>Solution 3: 0.0375 g (&#177;) &#945;-L-lipoic acid, oxidized form in 1 ml ethanol:</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="2">Combine solutions 1, 2, and 3 and bring the final volume to 100 ml. Store in dark at 4 &#176;C or freeze aliquots at -20 &#176;C. 
			Make small volumes of stocks for this mix so it is used quickly.</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Table 1C</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Nucleic acid mix, 100 ml</td>
		</tr>
		<tr>
			<td>To 60 ml of water add:</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 5&#39; -monophosphate, sodium salt</td>
			<td>1.74 g&#160;</td>
		</tr>
		<tr>
			<td>Cytidine 5&#39; -phosphate</td>
			<td>1.84 g&#160;</td>
		</tr>
		<tr>
			<td>Guanosine 2&#39; - and 3&#39; -monophosphate&#160;</td>
			<td>1.82 g&#160;</td>
		</tr>
		<tr>
			<td>OR</td>
			<td></td>
		</tr>
		<tr>
			<td>Guanosine 5&#39; -phosphate</td>
			<td>&#160;2.04 g</td>
		</tr>
		<tr>
			<td>Uridine 5&#39; -phosphate, disodium salt</td>
			<td>1.84 g</td>
		</tr>
		<tr>
			<td>Thymine (add last)</td>
			<td>0.63 g&#160;</td>
		</tr>
		<tr>
			<td colspan="2">Bring solution to 100 ml and store in the dark at 4 &#176;C or freeze aliquots at -20 &#176;C. 
			Make small volumes of stocks for this mix so it is used quickly.</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Table 1D</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Mineral Mix, 1 L</td>
		</tr>
		<tr>
			<td>MgCl2&#8226;6H2O</td>
			<td>4.1 g&#160;</td>
		</tr>
		<tr>
			<td>Sodium citrate</td>
			<td>2.9 g&#160;</td>
		</tr>
		<tr>
			<td>Potassium citrate monohydrate</td>
			<td>4.9 g&#160;</td>
		</tr>
		<tr>
			<td>CuCl2&#8226;2H2O</td>
			<td>0.07 g</td>
		</tr>
		<tr>
			<td>MnCl2&#8226;4H2O</td>
			<td>0.2 g</td>
		</tr>
		<tr>
			<td>ZnCl2</td>
			<td>0.1 g&#160;</td>
		</tr>
		<tr>
			<td>Fe(NH4)2(SO4)2&#8226;6H2O</td>
			<td>0.6 g&#160;</td>
		</tr>
		<tr>
			<td>CaCl2&#8226;2H2O (always add last)</td>
			<td>0.2 g&#160;</td>
		</tr>
		<tr>
			<td colspan="2">Make small volumes of stocks for this mix so it is used quickly.</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Table 1E</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Other Components</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>450 mM</td>
		</tr>
		<tr>
			<td>Choline di-acid citrate</td>
			<td>2 mM</td>
		</tr>
		<tr>
			<td>myo-Inositol</td>
			<td>2.4 mM</td>
		</tr>
		<tr>
			<td>D-Glucose</td>
			<td>1.45 M</td>
		</tr>
		<tr>
			<td>Hemin chloride</td>
			<td>2 mM in 0.1 N NaOH pH 8.0</td>
		</tr>
		<tr>
			<td>HEPES, sodium salt</td>
			<td>1 M stock solution</td>
		</tr>
		<tr>
			<td>Cholesterol</td>
			<td>5 mg/ml in ethanol</td>
		</tr>
		<tr>
			<td>Lactalbumin enzymatic hydrolysate</td>
			<td>170 mg/ml</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">Table 1F</td>
		</tr>
		<tr>
			<td colspan="2" style="text-align:center">M9 Buffer, 1 L</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>3 g&#160;</td>
		</tr>
		<tr>
			<td>Na2HPO4</td>
			<td>6 g&#160;</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>5 g&#160;</td>
		</tr>
		<tr>
			<td>H2O</td>
			<td>1 L</td>
		</tr>
		<tr>
			<td>Autoclave 30 min</td>
			<td></td>
		</tr>
		<tr>
			<td>1 M MgSO4 (sterile)</td>
			<td>1 ml&#160;</td>
		</tr>
	</tbody>
</table>
Table 1.&#160;Recipes for components of mCeHR and mCeHR.
<table border="0" cellpadding="0" cellspacing="0" width="486">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:109px;">Bombardment</td>
			<td style="width:141px;">Lines with wild type rescue</td>
			<td style="width:148px;">Lines with rescue / transgene</td>
			<td style="width:88px;">Stable lines</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:109px;">1</td>
			<td style="width:141px;">2</td>
			<td style="width:148px;">2</td>
			<td style="width:88px;">1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:109px;">2</td>
			<td style="width:141px;">8</td>
			<td style="width:148px;">5</td>
			<td style="width:88px;">0</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:109px;">3</td>
			<td style="width:141px;">4</td>
			<td style="width:148px;">4</td>
			<td style="width:88px;">2</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:109px;">4</td>
			<td style="width:141px;">5</td>
			<td style="width:148px;">2</td>
			<td style="width:88px;">1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:109px;">5</td>
			<td style="width:141px;">5</td>
			<td style="width:148px;">3</td>
			<td style="width:88px;">1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:109px;">Average</td>
			<td style="width:141px;">4.8</td>
			<td style="width:148px;">3.2</td>
			<td style="width:88px;">1</td>
		</tr>
	</tbody>
</table>
Table 2.&#160;Average number of transgenic C. elegans generated using microparticle bombardment.

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

Nanyang Technological University

Research

JoVE Journal

Biology

17.0K Views.  University of Maryland.  C. elegans is meestal gekweekt op vaste agar platen of in vloeibare culturen bezaaid met E. coli. Om te voorkomen dat bacteriële bijproducten van verstorende toxicologische en nutritionele studies, hebben we gebruik gemaakt van een axenische vloeibaar medium, CeHR, te groeien en te synchroniseren een groot aantal wormen voor een reeks afgeleide toepassingen. 

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

The Nematode Caenorhabditis Elegans - A Versatile In Vivo Model to Study Host-microbe Interactions

We demonstrate a method using Caenorhabditis elegans as a model host to study microbial interaction. Microbes are introduced via the diet making the intestine the primary location for disease. The nematode intestine structurally and functionally mimics mammalian intestines and is transparent making it amenable to microscopic study of colonization. Here we show that pathogens can cause disease and death. We are able to identify microbial mutants that show altered virulence. Its conserved innate response to biotic stresses makes C. elegans an excellent system to probe facets of host innate immune interactions. We show that hosts with mutations in the dual oxidase gene cannot produce reactive oxygen species and are unable to resist microbial insult. We further demonstrate the versatility of the presented survival assay by showing that it can be used to study the effects of inhibitors of microbial growth. This assay may also be used to discover fungal virulence factors as targets for the development of novel antifungal agents, as well as provide an opportunity to further uncover host-microbe interactions. The design of this assay lends itself well to high throughput whole-genome screens, while the ability to cryo-preserve worms for future use makes it a cost-effective and attractive whole animal model to study.

The Nematode Caenorhabditis Elegans - A Versatile In Vivo Model to Study Host-microbe Interactions

Here, we present the nematode Caenorhabditis elegans as a versatile host model to study microbial interaction.

We demonstrate a method using Caenorhabditis elegans as a model host to study microbial interaction. Microbes are introduced via the diet making the ...

Genetics

Generation of Stable Transgenic C. elegans Using Microinjection

Transgenic Caenorhabditis elegans can be readily created via microinjection of a DNA plasmid solution into the gonad 1. The plasmid DNA rearranges to form extrachromosomal concatamers that are stably inherited, though not with the same efficiency as actual chromosomes 2. A gene of interest is co-injected with an obvious phenotypic marker, such as rol-6 or GFP, to allow selection of transgenic animals under a dissecting microscope. The exogenous gene may be expressed from its native promoter for cellular localization studies. Alternatively, the transgene can be driven by a different tissue-specific promoter to assess the role of the gene product in that particular cell or tissue. This technique efficiently drives gene expression in all tissues of C. elegans except for the germline or early embryo 3. Creation of transgenic animals is widely utilized for a range of experimental paradigms. This video demonstrates the microinjection procedure to generate transgenic worms. Furthermore, selection and maintenance of stable transgenic C. elegans lines is described.

This video demonstrates the technique of microinjection into the gonad of C. elegans to create transgenic animals.

Transgenic Caenorhabditis elegans can be readily created via microinjection of a DNA plasmid solution into the gonad 1.  The plasmid DNA rearranges to ...

Application of RNAi and Heat-shock-induced Transcription Factor Expression to Reprogram Germ Cells to Neurons in C. elegans

Studying the cell biological processes during converting the identities of specific cell types provides important insights into mechanism that maintain and protect cellular identities. The conversion of germ cells into specific neurons in the nematode Caenorhabditis elegans (C. elegans) is a powerful tool for performing genetic screens in order to dissect regulatory pathways that safeguard established cell identities. Reprogramming of germ cells to a specific type of neurons termed ASE requires transgenic animals that allow broad over-expression of the Zn-finger transcription factor (TF) CHE-1. Endogenous CHE-1 is expressed exclusively in two head neurons and is required to specify the glutamatergic ASE neurons fate, which can easily be visualized by the gcy-5prom::gfp reporter. A trans gene containing the heat-shock promoter-driven che-1 gene expression construct allows broad mis-expression of CHE-1 in the entire animal upon heat-shock treatment. The combination of RNAi against the chromatin-regulating factor LIN-53 and heat-shock-induced che-1 over-expression leads to reprogramming of germ cell into ASE neuron-like cells. We describe here the specific RNAi procedure and appropriate conditions for heat-shock treatment of transgenic animals in order to successfully induce germ cell to neuron conversion.

Application of RNAi and Heat-shock-induced Transcription Factor Expression to Reprogram Germ Cells to Neurons in C. elegans

This protocol describes how to study cellular processes during cell fate conversion in Caenorhabditis elegans in vivo. Using transgenic animals, allowing heat-shock promoter-driven overexpression of the neuron fate-inducing transcription factor CHE-1 and RNAi-mediated depletion of the chromatin-regulating factor LIN-53 germ cell to neuron reprogramming can be observed in vivo.

Studying the cell biological processes during converting the identities of specific cell types provides important insights into mechanism that maintain ...

Developmental Biology

A Caenorhabditis elegans Model System for Amylopathy Study

Amylopathy is a term that describes abnormal synthesis and accumulation of amyloid beta (A&beta;) in tissues with time. A&beta; is a hallmark of Alzheimer's disease (AD) and is found in Lewy body dementia, inclusion body myositis and cerebral amyloid angiopathy 1-4. Amylopathies progressively develop with time. For this reason simple organisms with short lifespans may help to elucidate molecular aspects of these conditions. Here, we describe experimental protocols to study A&beta;-mediated neurodegeneration using the worm Caenorhabditis elegans. Thus, we construct transgenic worms by injecting DNA encoding human A&beta;42 into the syncytial gonads of adult hermaphrodites. Transformant lines are stabilized by a mutagenesis-induced integration. Nematodes are age synchronized by collecting and seeding their eggs. The function of neurons expressing A&beta;42 is tested in opportune behavioral assays (chemotaxis assays). Primary neuronal cultures obtained from embryos are used to complement behavioral data and to test the neuroprotective effects of anti-apoptotic compounds.

A Caenorhabditis elegans Model System for Amylopathy Study

We describe methods to study aspects of amylopathies in the worm C. elegans. We show how to construct worms expressing human A&beta;42 in neurons and how to test their function in behavioral assays. We further show how to obtain primary neuronal cultures that can be used for pharmacological testing.

Amylopathy is a term that describes abnormal synthesis and accumulation of amyloid beta (A&beta;) in tissues with time. A&beta; is a hallmark of ...

Neuroscience

Generation of Transgenic C. elegans by Biolistic Transformation

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid generation time and short life span, easy and inexpensive maintenance, fully sequenced genome, and array of RNAi resources and mutant animals. Additionally, analysis of the C. elegans genome revealed a great similarity between worms and higher vertebrates, which suggests that research in worms could be an important adjunct to studies performed in whole mice or cultured cells. A powerful and important part of worm research is the ability to use transgenic animals to study gene localization and function. Transgenic animals can be created either via microinjection of the worm germline or through the use of biolistic bombardment. Bombardment is a newer technique and is less familiar to a number of labs. Here we describe a simple protocol to generate transgenic worms by biolistic bombardment with gold particles using the Bio-Rad PDS-1000 system. Compared with DNA microinjection into hermaphrodite germline, this protocol has the advantage of not requiring special skills from the operator with regards to identifying worm anatomy or performing microinjection. Further multiple transgenic lines are usually obtained from a single bombardment. Also in contrast to microinjection, biolistic bombardment produces transgenic animals with both extrachromosomal arrays and integrated transgenes. The ability to obtain integrated transgenic lines can avoid the use of mutagenic protocols to integrate foreign DNA. In conclusion, biolistic bombardment can be an attractive method for the generation of transgenic animals, especially for investigators not interested in investing the time and effort needed to become skilled at microinjection.

Generation of Transgenic C. elegans by Biolistic Transformation

Transgenic worms are commonly used in C. elegans research. Described is a simple, yet effective, protocol to introduce transgenes into worms using biolistic bombardment with DNA-coated gold particles. The effort involved and results of bombardment compare favorably with microinjection for the generation of transgenic animals.

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid ...

Culturing and Genetically Manipulating Entomopathogenic Nematodes

Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema are obligate parasites of insects that live in the soil. The main characteristic of their life cycle is the mutualistic association with the bacteria Photorhabdus and Xenorhabdus, respectively. The nematode parasites are able to locate and enter suitable insect hosts, subvert the insect immune response, and multiply efficiently to produce the next generation that will actively hunt new insect prey to infect. Due to the properties of their life cycle, entomopathogenic nematodes are popular biological control agents, which are used in combination with insecticides to control destructive agricultural insect pests. Simultaneously, these parasitic nematodes represent a research tool to analyze nematode pathogenicity and host anti-nematode responses. This research is aided by the recent development of genetic techniques and transcriptomic approaches for understanding the role of nematode secreted molecules during infection. Here, a detailed protocol on maintaining entomopathogenic nematodes and using a gene knockdown procedure is provided. These methodologies further promote the functional characterization of entomopathogenic nematode infection factors.

Entomopathogenic nematodes live in symbiosis with bacteria and together they successfully infect insects by undermining their innate immune system. To promote research on the genetic basis of nematode infection, methods for maintaining and genetically manipulating entomopathogenic nematodes are described.

Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema are obligate parasites of insects that live in the soil. The main characteristic ...

Immunology and Infection

Using Single-Worm Data to Quantify Heterogeneity in Caenorhabditis elegans-Bacterial Interactions

The nematode Caenorhabditis elegans is a model system for host-microbe and host-microbiome interactions. Many studies to date use batch digests rather than individual worm samples to quantify bacterial load in this organism. Here it is argued that the large inter-individual variability seen in bacterial colonization of the C. elegans intestine is informative, and that batch digest methods discard information that is important for accurate comparison across conditions. As describing the variation inherent to these samples requires large numbers of individuals, a convenient 96-well plate protocol for disruption and colony plating of individual worms is established.

Using Single-Worm Data to Quantify Heterogeneity in Caenorhabditis elegans-Bacterial Interactions

This protocol describes a 96-well disruption of individual bacterially colonized Caenorhabditis elegans following cold paralysis and surface bleaching&#160;to remove external bacteria. The resulting suspension is plated on agar plates to allow accurate, medium-throughput quantification of bacterial load in large numbers of individual worms.

The nematode Caenorhabditis elegans is a model system for host-microbe and host-microbiome interactions. Many studies to date use batch digests rather ...

Long-Term Culture of Individual Caenorhabditis elegans on Solid Media for Longitudinal Fluorescence Monitoring and Aversive Interventions

Caenorhabditis elegans are widely used to study aging biology. The standard practice in C. elegans aging studies is to culture groups of worms on solid nematode growth media (NGM), allowing the efficient collection of population-level data for survival and other physiological phenotypes, and periodic sampling of subpopulations for fluorescent biomarker quantification. Limitations to this approach are the inability to (1) follow individual worms over time to develop age trajectories for phenotypes of interest and (2) monitor fluorescent biomarkers directly in the context of the culture environment. Alternative culture approaches use liquid culture or microfluidics to monitor individual animals over time, in some cases including fluorescence quantification, with the tradeoff that the culture environment is contextually distinct from solid NGM. The WorMotel is a previously described microfabricated multi-well device for culturing isolated worms on solid NGM. Each worm is maintained in a well containing solid NGM surrounded by a moat filled with copper sulfate, a contact repellent for C. elegans, allowing longitudinal monitoring of individual animals. We find copper sulfate insufficient to prevent worms from fleeing when subjected to aversive interventions common in aging research, including dietary restriction, pathogenic bacteria, and chemical agents that induce cellular stress. The multi-well devices are also molded from polydimethylsiloxane, which produces high background artifacts in fluorescence imaging. This protocol describes a new approach for culturing isolated roundworms on solid NGM using commercially available polystyrene microtrays, originally designed for human leukocyte antigen (HLA) typing, allowing the measurement of survival, physiological phenotypes, and fluorescence across the lifespan. A palmitic acid barrier prevents worms from fleeing, even in the presence of aversive conditions. Each plate can culture up to 96 animals and easily adapts to a variety of conditions, including dietary restriction, RNAi, and chemical additives, and is compatible with automated systems for collecting lifespan and activity data.

Long-Term Culture of Individual Caenorhabditis elegans on Solid Media for Longitudinal Fluorescence Monitoring and Aversive Interventions

Here, we present a protocol to culture isolated individual nematodes on solid media for lifelong physiological parameter tracking and fluorescence quantification. This culture system includes a palmitic acid barrier around single-worm wells to prevent animals from fleeing, allowing the use of aversive interventions, including pathogenic bacteria and chemical stressors.

Caenorhabditis elegans are widely used to study aging biology. The standard practice in C. elegans aging studies is to culture groups of worms on solid ...

Long-Term Culture and Monitoring of Isolated Caenorhabditis elegans on Solid Media in Multi-Well Devices

The nematode Caenorhabditis elegans is among the most common model systems used in aging research owing to its simple and inexpensive culture techniques, rapid reproduction cycle (~3 days), short lifespan (~3 weeks), and numerous available tools for genetic manipulation and molecular analysis. The most common approach for conducting aging studies in C. elegans, including survival analysis, involves culturing populations of tens to hundreds of animals together on solid nematode growth media (NGM) in Petri plates. While this approach gathers data on a population of animals, most protocols do not track individual animals over time. Presented here is an optimized protocol for the long-term culturing of individual animals on microfabricated polydimethylsiloxane (PDMS) devices called WorMotels. Each device allows up to 240 animals to be cultured in small wells containing NGM, with each well isolated by a copper sulfate-containing moat that prevents the animals from fleeing. Building on the original WorMotel description, this paper provides a detailed protocol for molding, preparing, and populating each device, with descriptions of common technical complications and advice for troubleshooting. Within this protocol are techniques for the consistent loading of small-volume NGM, the consistent drying of both the NGM and bacterial food, options for delivering pharmacological interventions, instructions for and practical limitations to reusing PDMS devices, and tips for minimizing desiccation, even in low-humidity environments. This technique allows the longitudinal monitoring of various physiological parameters, including stimulated activity, unstimulated activity, body size, movement geometry, healthspan, and survival, in an environment similar to the standard technique for group culture on solid media in Petri plates. This method is compatible with high-throughput data collection when used in conjunction with automated microscopy and analysis software. Finally, the limitations of this technique are discussed, as well as a comparison of this approach to a recently developed method that uses microtrays to culture isolated nematodes on solid media.

Long-Term Culture and Monitoring of Isolated Caenorhabditis elegans on Solid Media in Multi-Well Devices

Presented here is an optimized protocol for culturing isolated individual nematodes on solid media in microfabricated multi-well devices. This approach allows individual animals to be monitored throughout their lives for a variety of phenotypes related to aging and health, including activity, body size and shape, movement geometry, and survival.

The nematode Caenorhabditis elegans is among the most common model systems used in aging research owing to its simple and inexpensive culture techniques, ...

C. elegans Maintenance

Ceanorhabditis elegans has been, and is still, used to great success as a model organism for studying a variety of developmental, genetic, molecular and even physical phenomena. In order to use C. elegans to its full potential, proper care and attention to the basic maintenance of this powerful organism is essential.
In this video you will learn the basic housing and feeding requirements of C. elegans, how to correctly handle and manipulate worms using a worm pick and how to freeze and recover important worm stocks. Towards the end of the video we will visit a few applications of modifying the housing, feeding and manipulation of these important animals.

Maintenance of Caenorhabditis elegans

Ceanorhabditis elegans has been, and is still, used to great success as a model organism for studying a variety of developmental, genetic, molecular and ...

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

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