Abstract
Small, genetically tractable species such as larval zebrafish, Drosophila, or Caenorhabditis elegans have become key model organisms in modern neuroscience. In addition to their low maintenance costs and easy sharing of strains across labs, one key appeal is the possibility to monitor single or groups of animals in a behavioural arena while controlling the activity of select neurons using optogenetic or thermogenetic tools. However, the purchase of a commercial solution for these types of experiments, including an appropriate camera system as well as a controlled behavioural arena, can be costly. Here, we present a low-cost and modular open-source alternative called ‘FlyPi’. Our design is based on a 3D-printed mainframe, a Raspberry Pi computer, and high-definition camera system as well as Arduino-based optical and thermal control circuits. Depending on the configuration, FlyPi can be assembled for well under €100 and features optional modules for light-emitting diode (LED)-based fluorescence microscopy and optogenetic stimulation as well as a Peltier-based temperature stimulator for thermogenetics. The complete version with all modules costs approximately €200 or substantially less if the user is prepared to ‘shop around’. All functions of FlyPi can be controlled through a custom-written graphical user interface. To demonstrate FlyPi’s capabilities, we present its use in a series of state-of-the-art neurogenetics experiments. In addition, we demonstrate FlyPi’s utility as a medical diagnostic tool as well as a teaching aid at Neurogenetics courses held at several African universities. Taken together, the low cost and modular nature as well as fully open design of FlyPi make it a highly versatile tool in a range of applications, including the classroom, diagnostic centres, and research labs.
Highlights
The advent of protein engineering has brought about a plethora of genetically encoded actuators and sensors that have revolutionised neuroscience as we knew it but a mere decade ago
In tandem, falling prices of high-performance chargecoupled device (CCD) chips and optical components such as lenses and spectral filters mean that today, already a basic webcam in combination with coloured, transparent plastic or a diffraction grating may suffice to perform sophisticated optical measurements [11,12]
The basic FlyPi can resolve samples down to approximately 10 microns, acquire video at up to 90 Hz, and acquire time-lapse series over many hours. It consists of the 3D-printed mainframe (Fig 1A–1D), one Raspberry Pi 3 single-board computer (RPi3) computer with a Pi camera and off-the-shelf objective lens, one Arduino-Nano microcontroller, as well as a custom printed circuit board (PCB) for flexible attachment of a wide range of actuators and sensors (Fig 1C)
Summary
The advent of protein engineering has brought about a plethora of genetically encoded actuators and sensors that have revolutionised neuroscience as we knew it but a mere decade ago. Modern biosciences today stand at a precipice of technological possibilities, in which a functional neuroscience laboratory set-up, capable of delivering high-quality data over a wide range of experimental scenarios, can be built from scratch for a mere fraction of the cost traditionally required to purchase any one of its individual components.
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