The OptoGenBox – a device for long-term optogenetics in C. elegans

Abstract

Optogenetics controls neural activity and behavior in living organisms through genetically targetable actuators and light. This method has revolutionized biology and medicine as it allows controlling cells with high temporal and spatial precision. Optogenetics is typically applied only at short time scales, for instance to study specific behaviors. Optogenetically manipulating behavior also gives insights into physiology, as behavior controls systemic physiological processes. For example, arousal and sleep affect aging and health span. To study how behavior controls key physiological processes, behavioral manipulations need to occur at extended time scales. However, methods for long-term optogenetics are scarce and typically require expensive compound microscope setups. Optogenetic experiments can be conducted in many species. Small model animals such as the nematode C. elegans have been instrumental in solving the mechanistic basis of medically important biological processes. We developed the OptoGenBox, an affordable stand-alone and simple-to-use device for long-term optogenetic manipulation of C. elegans. The OptoGenBox provides a controlled environment and is programmable to allow the execution of complex optogenetic manipulations over long experimental times of many days to weeks. To test our device, we investigated how optogenetically increased arousal and optogenetic sleep deprivation affect survival of arrested first larval stage C. elegans. We optogenetically activated the nociceptive ASH sensory neurons using ReaChR, thus triggering an escape response and increase in arousal. In addition, we optogenetically inhibited the sleep neuron RIS using ArchT, a condition known to impair sleep. Both optogenetic manipulations reduced survival. Thus, the OptoGenBox presents an affordable system to study the long-term consequences of optogenetic manipulations of key biological processes in C. elegans and perhaps other small animals.

Keywords:

• Caenorhabditis elegans
• C. elegans
• optogenetics
• arousal
• sleep
• lifespan

Acknowledgements

The authors thank the CGC, which is funded by NIH Office of Research Infrastructure Programs (P40 OD010440), for the N2 strain. The mechanics workshop at the MPI BPC provided us with valuable advice for the design and parts of the OptoGenBox. The authors also like to thank Juliane Haase for assisting with laboratory work.

Author contributions

IB and FJ designed the OptoGenBox. IB designed, performed and analyzed the experiments and wrote the manuscript. FJ built the hardware of the OptoGenBox and contributed to the manuscript. PS programmed the software of the OptoGenBox. HB acquired funding, conceived the project, supervised the work, and edited the manuscript.

Disclosure statement

The authors declare that they have no competing interest.

Additional information

Funding

This work was funded by the Max Planck Society (Max Planck Research Group), a European Research Council Starting Grant (ID: 637860, SLEEPCONTROL), and the University of Marburg.