Biology subjects

Gyoja, F.

Publications and source records attributed to Gyoja, F..

3 recordsLinked to original sources

bioRxiv2026

Spatial transcriptomic landscape of the Ciona adult brain: functional zonalisation and cellular composition in a sessile chordate brain and a novel insight into neural gland function

The ascidian Ciona provides a key model for understanding the evolutionary origin of the vertebrate brain. While the larval nervous system has been extensively characterized, the molecular and cellular organization of the adult neural complex remains poorly defined. Here, we generated spatial transcriptomic maps of the adult Ciona neural complex from three individuals, with four serial sections per donor, using the 10x Visium platform. Clustering-based analysis identified five major tissue domains, including the cerebral ganglion, neural gland, ciliated funnel, neural gland duct/dorsal strand, and body wall muscle. To further refine spatial resolution, we computationally reconstructed approximately 980 super-resolution gene expression maps by integrating transcriptomic measurements with histological image features. The super-resolution maps enabled precise delineation of molecular territories within the neural complex. In the cerebral ganglion, high-resolution reconstruction revealed clear molecular zonation, distinguishing the cortex and medulla. Within the cortex, the central region facing the neural gland and anteroposterior distal regions showed distinct molecular properties. In the neural gland, we identified coordinated enrichment of cell-cell interaction- and extracellular matrix-related genes, suggesting specialized structural and physiological properties. We propose that the neural gland play a pivotal role for the cerebral ganglion in maintaining homeostasis, supporting development, and providing a signaling interface, which is reminiscent of a primitive form of the choroid plexus and meninges found in vertebrates. Together, this study provides the first spatially resolved transcriptomic atlas of the adult Ciona neural complex and establishes a molecular framework for investigating functional regionalization and brain evolution in chordates.

genomics↗

bioRxiv2025

How opsins diversified after the teleost whole-genome duplication: Insights from two parietopsins of the red piranha, Pygocentrus nattereri

The teleost whole-genome duplication (TGD) contributed to functional diversification of opsins. Some TGD paralogs, including those of parapinopsin (PP), Vertebrate Ancient (VA) opsin, and long wavelength-sensitive (LWS) opsin, show different absorption spectra and/or expression patterns. However, our knowledge of detailed evolutionary processes and mechanisms by which TGD contributed to opsin diversification is still limited. Here, we report that TGD paralogs of parietopsin (PT1 and PT2) are retained in extant species. While most species, including the zebrafish, have only PT1, several characins, including the red piranha (Pygocentrus nattereri), retain both PT1 and PT2. The Mexican tetra (Astyanax mexicanus) and catfishes have only PT2. To assess the degree of functional diversification between PT1 and PT2, we characterized spectral properties and expression patterns. Maximum absorption spectra differ slightly among PTs. Those of red piranha PT1, PT2, Mexican tetra PT2, and Japanese catfish (Silurus asotus) PT2 were located at 517 nm, 528 nm, 517 nm, and ~535 nm, respectively. Fluorescence in situ hybridization showed that (1) piranha PT1 and PT2 are expressed in the same pineal cells, and (2) they are also co-expressed with PP1. Based on these findings, functional diversification of opsins after gene duplication is discussed.

evolutionary biology↗

bioRxiv2023

Comparative single-cell transcriptomic analysis reveals key differentiation drivers and the potential origin of the vertebrate retina

Despite known single-cell expression profiles in vertebrate retinas, understanding of their developmental and evolutionary expression patterns among homologous cell classes remains limited. We examined and compared approximately 240, 000 retinal cells from four species and found significant similarities among homologous cell classes, indicating inherent regulatory patterns. To understand these shared patterns, we constructed gene regulatory networks for each developmental stage for three of these species. We identified 690 regulons governed by 530 regulators across three species, along with 10 common cell class-specific regulators and 16 preserved regulons. RNA velocity analysis pinpointed conserved putative driver genes and regulators to retinal cell differentiation in both mouse and zebrafish. Investigation of the origins of retinal cells by examining conserved expression patterns between vertebrate retinal cells and invertebrate Ciona intestinalis photoreceptor-related cells implied functional similarities in light transduction mechanisms. Our findings offer insights into the evolutionarily conserved regulatory frameworks and differentiation drivers of vertebrate retinal cells.

bioinformatics↗