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C. elegans requires cholesterol to progress through the four larval stages. The Andersen lab found that some filters were removing cholesterol from K medium and S medium, and most worms arrested in larval development. For this reason, we add cholesterol after filtration or autoclaving of media for NGMA plates.

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For NGM/HGM plates

Use the unfiltered but sterile 5 mg/mL cholesterol in ethanol. To make it:

1. Take an autoclaved sterile 250 mL bottle.
2. Add 1 g of powdered cholesterol (VWR #0433-250G) to the bottle.
3. Add 200 mL of 100% ethanol.
4. Cap and shake to resuspend.
5. Store at room temperature on the reagents shelf for up to six months.