title: Neuropeptides regulate swimming depth of Platynereis larvae.
abstract: Cilia-based locomotion is the major form of locomotion for microscopic planktonic organisms in the ocean. Given their negative buoyancy, these organisms must control ciliary activity to maintain an appropriate depth. The neuronal bases of depth regulation in ciliary swimmers are unknown. To gain insights into depth regulation we studied ciliary locomotor control in the planktonic larva of the marine annelid, Platynereis. We found several neuropeptides expressed in distinct sensory neurons that innervate locomotor cilia. Neuropeptides altered ciliary beat frequency and the rate of calcium-evoked ciliary arrests. These changes influenced larval orientation, vertical swimming, and sinking, resulting in upward or downward shifts in the steady-state vertical distribution of larvae. Our findings indicate that Platynereis larvae have depth-regulating peptidergic neurons that directly translate sensory inputs into locomotor output on effector cilia. We propose that the simple circuitry found in these ciliated larvae represents an ancestral state in nervous system evolution.
authors: Max Planck Institute for Developmental Biology, 72076 Tübingen,  Germany.
authors: Markus
authors: M
authors: Conzelmann
authors: Sarah-Lena
authors: SL
authors: Offenburger
authors: Albina
authors: A
authors: Asadulina
authors: Timea
authors: T
authors: Keller
authors: Thomas A
authors: TA
authors: Münch
authors: Gáspár
authors: G
authors: Jékely
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002923:Cilia / Q000378:metabolism; D004594:Electrophysiology / Q000379:methods; D019835:FMRFamide / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007814:Larva / Q000378:metabolism / Q000502:physiology; D008124:Locomotion; D008969:Molecular Sequence Data; D009132:Muscles / Q000502:physiology; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism*; D011077:Polychaeta / Q000196:embryology* / Q000502:physiology*; D013550:Swimming
chemical_list: D009479:Neuropeptides; D019835:FMRFamide