Researchers have unveiled a groundbreaking discovery regarding the common sea urchin species, Paracentrotus lividus, revealing it possesses an ‘all-body brain.’ The most surprising and perhaps most important discovery was the result of a pioneering study by Dr. Jack Ullrich-Lüter. In addition, he is the first author at Museum für Naturkunde Berlin. The research aimed to explore how a single genome can give rise to two remarkably different body plans: the bilaterally symmetrical larva and the adult sea urchin characterized by its fivefold radial symmetry.
The study’s main focus was on determining which particular cell types are responsible for the change from larva to adult. From this ocean of P. lividus specific neurons, researchers found hundreds of unique neurons. These neurons express a suite of both echinoderm-specific “head” genes and highly conserved genes typically associated with the vertebrate central nervous system. This finding points to an organizational complexity of the neural ground plan of P. lividus previously unappreciated.
The recently published research points to an interesting find. Additionally, it’s the first to isolate a unique P. lividus cell type that entirely fuses melanopsin and go-opsin. This unusual combination is a testament to an amazing ability to pick up and process light stimuli. It indicates that this species of the prickly invertebrate has an underappreciated visual prowess. Such results would radically change the prevailing view of sensory perception in echinoderms.
The collaborative effort for this research involved multiple institutions, including the Stazione Zoologica Anton Dohrn in Naples, the Laboratoire de Biologie du Développement de Villefranche-sur-Mer, and the Institut de Génomique Fonctionnelle de Lyon. The team utilized advanced techniques such as HCR (hybridization chain reaction) with specific probes targeting opsin3.2 and opsin4 to analyze the opsin-positive neuronal clusters in P. lividus. The genome of this squidsheernet species contains numerous loci encoding opsin genes, molecules that are integral to photoreception.
Next, the researchers looked at transcription factor orthologs that are known to modify the establishment of photoreceptor cell fate in other organisms. They sequenced and measured the average expression levels of these opsin genes and found that all of these transcription factor orthologs were expressed in P. lividus. The comprehensive analysis provided a clearer picture of how these genetic components contribute to the sea urchin’s neural architecture and sensory capabilities.
The findings from this pivotal study have been published with the DOI: 10.1126/sciadv.adx7753, contributing valuable insights into the evolutionary biology of echinoderms and expanding the understanding of neural complexity in marine organisms.