provided by Shunsuke Yaguchi

Researchers at University of Tsukuba identified a brain-like cluster of neurons in sea urchin larvae, traditionally considered lacking a brain, that regulates light-responsive behavior. These neurons possess a subset of gene expression profiles similar to those found in vertebrate brains, offering new insights into the evolutionary origins of brain functions that may trace back to a common ancestor in the bilaterian lineage of animals.

Tsukuba, Japan—A cluster of non-visual, light-sensitive neurons was discovered in the anterior apical neuroectoderm of sea urchin larvae. These neurons respond to light stimuli without forming visual images, suggesting the presence of a central regulatory network in echinoderms analogous to the vertebrate brain. The neuronal cluster expresses non-visual opsin (Opn5L), a light-sensitive protein, as well as key regulatory genes, such as rx, otx, six3, and lhx6, which are involved in vertebrate brain development. Integrative analysis revealed that functional disruption of Opn5L impairs light-dependent swimming behavior. The molecular profile of these neurons partially overlaps with that of vertebrate brain regions, suggesting the conservation of ancestral brain-like functions in sea urchin larvae.

Comprehensive cross-phylogenetic comparisons of the developmental processes involving non-visual opsin-expressing neurons and their surrounding regions are anticipated to yield novel theories and insights into central nervous system evolution and diversification, including the vertebrate brain.

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This work is supported by JST PRESTO Grant number JPMJPR194C, JST A-STEP Grant number JPMJTR204E, JSPS KAKENHI Grant number 23K23933, the Toray Science Foundation and Takeda Science Foundation to S. Yaguchi, JST PRESTO Grant number JPMJPR1945 and JSPS KAKENHI Grant Numbers 19K20406 and 23K11312 to K.Tsuyuzaki, AMED CREST Grant number 22gm1510007 and The Naito Foundation to T. Yamashita.

Original Paper

Title of original paper:

Non-Visual Photoreceptive Brain Specification in Sea Urchin Larvae

Journal:

Nature Communications

DOI:

10.1038/s41467-025-65628-9

Correspondence

Associate Professor YAGUCHI Shunsuke
Institute of Life and Environmental Sciences, University of Tsukuba

Specially Appointed Lecturer TSUYUZAKI Koki
Department of Artificial Intelligence Medicine, Graduate School of Medicine, Chiba University

Assistant Professor YAMASHITA Takahiro
Department of Biophysics, Graduate School of Science, Kyoto University

Professor YAMAMOTO Takashi
Genome Editing Innovation Center, Hiroshima University

Related Link

Institute of Life and Environmental Sciences