A simple high-throughput method for automated detection of Drosophila melanogaster light-dependent behaviours

Abstract

Background Like most living organisms, the fruit fly Drosophila melanogaster exhibits strong and diverse behavioural reactions to light. Drosophila is a diurnal animal that displays both short- and long-term responses to light, important for, instance, in avoidance and light wavelength preference, regulation of eclosion, courtship, and activity, and provides an important model organism for understanding the regulation of circadian rhythms both at molecular and circuit levels. However, the assessment and comparison of light-based behaviours is still a challenge, mainly due to the lack of a standardised platform to measure behaviour and different protocols created across studies. Here, we describe the Drosophila Interactive System for Controlled Optical manipulations (DISCO), a low-cost, automated, high-throughput device that records the flies’ activity using infrared beams while performing LED light manipulations. Results To demonstrate the effectiveness of this tool and validate its potential as a standard platform, we developed a number of distinct assays, including measuring the locomotor response of flies exposed to sudden darkness (lights-off) stimuli. Both white-eyed and red-eyed wild-type flies exhibit increased activity after the application of stimuli, while no changes can be observed in Fmr1 null allele flies, a model of fragile X syndrome. Next, to demonstrate the use of DISCO in long-term protocols, we monitored the circadian rhythm of the flies for 48 h while performing an alcohol preference test. We show that increased alcohol consumption happens intermittently throughout the day, especially in the dark phases. Finally, we developed a feedback-loop algorithm to implement a place preference test based on the flies’ innate aversion to blue light and preference for green light. We show that both white-eyed and red-eyed wild-type flies were able to learn to avoid the blue-illuminated zones. Conclusions Our results demonstrate the versatility of DISCO for a range of protocols, indicating that this platform can be used in a variety of ways to study light-dependent behaviours in flies.

Evidence for Prepulse Inhibition of Visually Evoked Motor Response in Drosophila melanogaster

“…The flies were maintained in vials at 25 °C, 12:12 h light/dark cycle, 60% humidity, and fed with Fisherbrand Jazz-Mix Drosophila food supplemented with 8.3% yeast extract (Fisher Scientific, Lund, Sweden). Importantly, although previous studies have shown that white-eyed flies are more responsive to lights-off stimuli [ 30 ], red-eyed flies were used in this study to increase the applicability of the results to a broader range of researchers. Throughout the study, experiments were performed within the light phases (ZT 0–12) of the light/dark cycle, covering the full scope of manipulation and testing of the flies.…”

“…As previously described [ 30 ], the DISCO apparatus is based on the MB5 MultiBeam Activity Monitor (TriKinetics Inc., Waltham, MA, USA), which has 16 independent tube slots, each equipped with 17 infrared beams for movement assessment. Three LED lights are connected to the MB5 Monitor per fly slot, uniformly spaced, and regulated by an Arduino Uno microcontroller (Arduino, Milan, Italy), which in turn is programmed to communicate with the MATLAB environment version R2018b (MathWorks, Natick, MA, USA) through the Legacy NeoPixel Add-On Library.…”

“…A custom-made MATLAB routine was used to calculate the movement response to stimuli by subtracting the average movement counts for 3 s after a given stimulus from the baseline measure 3 s before the same point, disregarding the exact second in which the stimulus was presented, here named as startle index. Similar MATLAB routines can be found as supplementary material in a previous article describing the DISCO platform [ 30 ].…”

“…Recently, our group developed a novel platform for high-throughput screening of the flies’ light-based behaviors, named DISCO ( Drosophila Interactive System for Controlled Optical manipulations), which is able to record second-by-second movements from individual flies [ 30 ]. Making use of this device, we showed that one-second lights-off stimuli increased Drosophila ’s locomotion for both red-eyed and white-eyed flies, of which populational response ratios were remarkably similar to that from visually evoked giant fiber escape responses [ 30 ]. Notably, we also showed that a fly model of Fragile X syndrome ( Fmr1 null allele), which displays deficits in sensory responses [ 31 ], does not exhibit increased motor response after lights-off stimuli [ 30 ].…”

“…Making use of this device, we showed that one-second lights-off stimuli increased Drosophila ’s locomotion for both red-eyed and white-eyed flies, of which populational response ratios were remarkably similar to that from visually evoked giant fiber escape responses [ 30 ]. Notably, we also showed that a fly model of Fragile X syndrome ( Fmr1 null allele), which displays deficits in sensory responses [ 31 ], does not exhibit increased motor response after lights-off stimuli [ 30 ].…”