The inebri-actometer: a device for measuring the locomotor activity of Drosophila exposed to ethanol vapor

Drosophila melanogaster can be used as a model organism for probing the gen etic basis for alcohol sensitivity. In this paper, we describe a new device , the inebri-actometer, which measures the locomotor activity of up to 128 individual flies simultaneously. The device consists of 128 pairs of emitte r/detector photodiodes connected in series through a computer interlink. A single fly is placed in each of the 128 chambers and humidified air or air containing variable amounts of ethanol vapor is pumped through the chambers . When a fly blocks the infrared signal transmitted by an emitter photodiod e, the computer records one movement for that fly. We present preliminary r esults showing the effect of ethanol on the activity of wild-type Oregon R Drosophila. Five preliminary runs with 95% ethanol vapor revealed that this concentration induces an approximately 3- to 4-fold increase in locomotor activity which peaks at about 5 min after the addition of ethanol vapor. Th is is followed by a gradual decrease in activity leading to a nearly total cessation of movement after 30 min. Statistically significant dose-related activity increases were obtained for ethanol concentrations of 8, 19, 50, a nd 100% of maximum, assessed in two replications at each dose. Unlike the c omplete suppression of locomotion seen in the last 10 min of the session at maximum ethanol exposure, the initial stimulation effect at the 19% concen tration was maintained across the 30-min session. (C) 2001 Elsevier Science B.V. All rights reserved.