The negative geotactic behavior is the innate escape mechanism exhibited by a Drosophila fly. CsBz flies (Drosophila melanogaster) which are cultured in labs in Corn meal agar media bottles are often seen near the cotton plug at the mouth of the culture bottles. Fruit fly single lines isolated from the environment can be checked for their geotactic behaviour and compared with CsBz flies using the Geotactic assay.
Protocol for the assay.
- From the selected media bottle consisting of staged flies, transfer the flies into a sugar tube by tapping it on banger and cotton plug the tube.
- Subject the tube to the freezing temperature of -4 degree C in a freezer for 10 minutes.
- Transfer the unconscious flies to a petri plate.
- With the help of brush, transfer one single fly to an individual test tube.
- Let the flies stay in the tubes and gain proper consciousness for 30 minutes.
- Insert one single fly from the test tube into the clean, 30 cm long glass tube and cotton plug the opening of the tube.
- Tap the glass tube on the banger so the fly falls on the cotton plug and start the stopwatch as soon as the fly starts climbing.
- Allow the fly to climb for 30 seconds and note the observations.
30cm long glass tube used for the geotactic assay.
Ref.
Linderman et. al. for Infection related defects in chill coma recovery and negative geotaxis in Drosophila melanogaster, 2012.