Encyclopedia of Experiments: Biology
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-First, obtain a set number of adult Drosophila. The testing chamber for the climbing assay is composed of two vials taped together. One of these vials should be marked with a line.
Without carbon dioxide anesthesia, which can impair climbing behavior, transfer a set number of flies to the testing chamber. Allow the flies to recover for a predetermined amount of time. With the marked side of the chamber down, firmly tap the chamber on a mouse pad placed on a solid surface. This will force the flies to the bottom of the chamber. The climbing assay takes advantage of Drosophila's natural tendency to climb upwards against gravity, a behavior called negative geotaxis.
During the trial, the flies shouldn't be exposed to direct sunlight because the flies might display phototaxis behavior, or movement in response to light stimulus. Record the number of flies that reach or pass the line. Then obtain the percent pass rate by dividing this number by the total number of flies tested. Allow the flies to recover before repeating the trial. In the example, we will observe a fly climbing assay being used to assess Drosophila motor function after chemical mutagenesis.
-To begin, collect homozygous flies from lines belonging to the ENU mutagenized collection of Drosophila mutants mapped to the second chromosome. Flip the flies aged 10 to 12 days into a testing chamber without anesthesia one line at a time and allow them to recover for five minutes.
With the five-centimeter line marked side down, forcibly tap the chamber three times on a mouse pad placed on a solid surface so that all flies begin the assay at the bottom. Observe fly locomotion over a period of 10 seconds. Record the number of flies that reach or pass the five-centimeter line within this time as well as the total number of flies tested. Wait one minute before starting a second trial. Repeat a minimum of three trial replicates per line.