Overview
This video describes a feeding assay for fruit flies in which colored food is used to monitor feeding and the effect added compounds may have on feeding activity. The example protocol tests the effects of several endocrine disrupting chemicals (EDC).
Protocol
This protocol is an excerpt from Bovier et al., Methods to Test Endocrine Disruption in Drosophila melanogaster, J. Vis. Exp. (2019).
1. Feeding Assay
NOTE: This assay is recommended to test if the presence of the selected EDC in the medium could affect feeding of flies.
- Put 15 young flies in vials containing Cornmeal medium (CM) supplemented with different concentrations of the selected EDC and a coloring food. Allow flies to feed on the media for 1 day.
NOTE: For example, use red dye no. 40 (1 mg/mL). - Put 15 young flies in vials containing CM supplemented with the solvent alone and a coloring food for control. Allow flies to feed on the media for 1 day.
- Anesthetize individually each group of flies with ether.
- Transfer flies of each group to a cylindrical glass container (etherizer) with a funnel inserted into the open end, inverting the vial over the funnel and gently tapping the two containers together to make the flies fall into the etherizer.
NOTE: The funnel will prevent them from getting out of the etherizer. - Knock flies down by gently tapping the etherizer on a soft surface, such as a mouse-pad, and quickly replace the funnel with an ether-soaked cotton and gauze plug.
- Wait about 1 min until the flies fall to the bottom and stop moving.
NOTE: Do not exceed the time or the flies will die.
- Transfer flies of each group to a cylindrical glass container (etherizer) with a funnel inserted into the open end, inverting the vial over the funnel and gently tapping the two containers together to make the flies fall into the etherizer.
- Put immobilized flies under a stereo-microscope and compare the abdominal coloring of each treatment group with respect to the control group.
Subscription Required. Please recommend JoVE to your librarian.
Materials
| Name | Company | Catalog Number | Comments |
| 17α-Ethinylestradiol | Sigma | E4876-1G | |
| Agar for Drosophila medium | BIOSIGMA | 789148 | |
| Bisphenol A | Sigma | 239658-50G | |
| Bisphenol AF | Sigma | 90477-100MG | |
| Cornmeal | CA' BIANCA | ||
| Diethyl ether | Sigma | ||
| Drosophila Vials | BIOSIGMA | 789008 | 25 mm x 95 mm |
| Drosophila Vials | BIOSIGMA | 789009 | 29 mm x 95 mm |
| Drosophila Vials | Kaltek | 187 | 22 mm x 63 mm |
| Ethanol | FLUKA | 2860 | |
| Etherizer | Crafts | cylindrical glass container with a cotton plug | |
| Hand blender Pimmy | Ariete | food processor | |
| Instant Success yeast | ESKA | Powdered yeast | |
| Red dye no. 40 | SIGMA | 16035 | |
| Stereomicroscope with LED lights | Leica | S4E |
