Peptide-driven control of somersaulting in Hydra vulgaris

The cnidarian Hydra vulgaris has a simple nervous system with a few hundred neurons in distributed networks. Yet Hydra can perform somersaults, a complex acrobatic locomotion. To understand the neural mechanisms of somersaulting we used calcium imaging and found that Rhythmical Potential 1 (RP1) neurons activate before somersaulting. Decreasing RP1 activity or ablating RP1 neurons reduced somersaulting, while two-photon activation of RP1 neurons induced somersaulting. Hym-248, a peptide synthesized by RP1 cells, selectively generated somersaulting. We conclude that RP1 activity, via release of Hym-248, is necessary and sufficient for somersaulting. We propose a circuit model to explain the sequential unfolding of this locomotion, using integrate-to-threshold decision-making and cross-inhibition. Our work demonstrates that peptide-based signaling is used by simple nervous systems to generate behavioral fixed action patterns. , Detailed methods are provided in the online version of this paper.
Lead contact
Further information and requests for resources and reagents should be directed to and will be fulfilled by the Lead Contact, Rafael Yuste ([e-mail]).
Materials availability
Transgenic Hydra are available upon request.
Data and code availability
The data generated or analyzed during this study will be available through Mendeley as well as this repository. All the codes are available at GitHub (https://github.com/NTCColumbia). All data are archived at the NeuroTechnology Center at Columbia University.
EXPERIMENTAL MODEL AND SUBJECT DETAILS
Hydra
Hydra vulgaris AEP strains were maintained in the dark at 18°C in Hydra culture media (1mM CaCl2, 0.5mM NaHCO3, 0.33 mM MgSO4, 0.03 mM KCl). Hydra were fed freshly hatched Artemia nauplii three times a week and were starved for 1-2 days before an experiment.
Transgenic lines
In the study, we used newly created transgenic Hydra expressing GCaMP6s or GFP in RP1 ...,