Drosophila Cornmeal–Yeast Food
| Reagent | Vendor | Amount |
|---|---|---|
| Distilled H2O | 4 L | |
| Cornmeal (Quaker yellow) | Genesee Scientific | 400 g |
| Agar (Drosophila agar, 100 mesh) | Genesee Scientific | 24 g |
| Yeast (Red Star active dry yeast) | Genesee Scientific | 72 g |
| Dextrose | Fisher Scientific | 240 g |
| Sucrose | Fisher Scientific | 120 g |
| Methyl paraben | Josh's Frogs | 2 g |
| Mix of propionic acid (41.8%, v/v) and phosphoric acid (4.15%, v/v) | Fisher Scientific | 40 mL |
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1. Combine 1 L of distilled H2O with sucrose, dextrose, and yeast in a large pot on a hot plate and stir.
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2. Slowly add the cornmeal and continue stirring.
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3. While doing Steps 1 and 2, slowly add agar to 3 L of distilled H2O in a large pot on another hot plate while stirring. Boil until solution is clear.
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4. Pour the agar solution into the cornmeal solution while still on the hot plate. Solution should be steaming but not boiling.
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5. Pour solution into three separate 2-L glass beakers, cover each with foil, place the beakers in a metal tray, and autoclave on liquid setting at 18 PSI for 30 min at 121°C.
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6. While autoclaving, combine the acid mixture with methyl paraben.
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7. After autoclaving, recombine the three beakers’ contents into a single pot, add acid/methyl paraben mix, and stir well.
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8. (Optional): Add All-trans-retinal (ATR, 100 mm) to a final concentration of 1 mm.
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ATR+ food can also be prepared by melting a known volume of cornmeal food in the microwave, mixing in the ATR solution at 1:100, and then pouring the resulting 1 mm ATR food into bottles and/or vials as needed.
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9. Dispense into containers as needed.
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10. Store for up to 2 wk at 4°C.
