Whole-body connectome of a segmented annelid larva

Dynamics and emergence of metachronal waves in the ciliary band of a metazoan larva

Both natural and synthetic ciliary arrays exhibit diverse coordination patterns. Proper coordination of cilia is essential for the normal physiology of many organisms, from single cells to humans. Yet despite decades of research the mechanisms of cilia coordination remains disputed, particularly the question of how coordinated waves of activity known as metachronal waves arise in different ciliated systems. In many aquatic larvae that rely on ciliary motility to swim, the cilia are often arranged ornately in arrays or bands, along which robust metachronal waves propagate. Here, to resolve the origins of ciliary metachronism, we target the equatorial ciliary band of the marine annelid, Platynereis dumerelii, using whole-body high-speed imaging, and physical and biological manipulations. The results reveal an unprecedented wave structure featuring strong coupling within individual multiciliated cells that breaks down across cell boundaries, and complete absence of global coupling across the organism. Using laser ablation to create gaps in the ciliary band, we quantified the resulting disruption to wave propagation, revealing the extent of interciliary phase-locking and implicating steric interactions as an important contributor to coordination. The larvae also exhibit spontaneous whole-body ciliary arrests which allowed us to study wave emergence and re-establishment for the first time, revealing a novel role of the animal's nervous system in the dynamic coupling of cilia. ### Competing Interest Statement The authors have declared no competing interest.

Bluesky

Mechanism of barotaxis in marine zooplankton

Ciliated zooplankton larvae sense pressure by ciliary photoreceptor cells, which increase the beating of locomotor cilia via a serotonergic motor circuit leading to rapid upward swimming during barotaxis.

Nouvelle avancée dans la compréhension de la régénération chez un ver marin

Long de seulement quelques centimètres, le ver marin Platynereis dumerilii possède une faculté notable : il est capable de régénérer des parties entières de son corps suite à une blessure ou une amputation, et ce en seulement quelques jours.

Dynamic microvilli sculpt bristles at nanometric scale - Nature Communications

Bristleworms possess dedicated cells that can synthesize highly stereotypical bristles with sub-micrometric precision. Here, Ikeda and colleagues shed light on the underlying dynamics of cellular protrusions, revealing an extension-disassembly cycle that resembles a 3D printer.

Skurril: Meereswurm nutzt 3D-Druck

Patent der Natur: Ein simpler Meereswurm nutzt eine "hochmoderne" Technologie, um seine Borsten zu produzieren – er erzeugt sie mittels 3D-Druck. Sein