Speaker
Description
Marine invertebrate larvae with pelago-benthic life cycles employ distinct locomotory strategies: swimming larvae move by ciliary beating during the pelagic phase, while benthic adults use muscles for crawling. Despite the fundamental importance of this lifestyle and behavioural change, the developmental and evolutionary relationships between the underlying nervous systems remain poorly understood. Here, we investigate the developmental trajectories of ciliomotor and neuromuscular neurons using the marine annelid Platynereis dumerilii, a model organism featuring a biphasic life cycle and invariant development. We combine zygote microinjection of neuronal (GCaMP6s) and nuclear (H2A-mCherry) fluorescent markers with long-term live imaging on a custom-built light-sheet fluorescence microscope ("Flamingo") to capture neuronal development at high temporal resolution. Through semi-automated cell tracking, we reconstruct the complete developmental lineages of neurons associated with each locomotory mode. Here, we present preliminary findings from this ongoing study. Our analysis addresses two key questions: (1) Do ciliomotor and neuromuscular neurons arise from the same or distinct cell lineage? (2) Do these neurons follow conserved or divergent molecular differentiation programs? By integrating these lineage data with existing transcriptomic and connectomic datasets, we plan to map relationships between gene expression patterns, neuron identity, and circuit assembly onto the lineages. This work will provide new insights into the mechanisms driving neuronal differentiation during the pelagic-to-benthic transition and contributes to our understanding of the evolutionary origins of metazoan nervous systems.
