Biology subjects

Amano, R.

Publications and source records attributed to Amano, R..

3 recordsLinked to original sources

bioRxiv2026

Coupled transcriptomic divergence establishes a human-specific synaptic glial precursor state

The mammalian cerebral cortex is built from a conserved developmental program, yet exhibits profound species-specific complexity. To decode the regulatory changes driving human brain evolution, we reconstructed and aligned continuous single-cell differentiation trajectories across the developing human, macaque, mouse, and ferret cortices. This comparative framework revealed a fundamental principle of transcriptomic evolution during mammalian cortical development: while stable expression is the mammalian default, genes that diverge strictly shift their allocation to cell differentiation trajectories and developmental timing in tandem. By isolating these coupled regulatory shifts to the human lineage, we revealed that a canonical synaptic gene network uniquely redeployed into early human oligodendrocyte precursor cells (OPCs). Human, chimpanzee, and gorilla cortical organoids confirmed that this neuron-like OPC state is an exclusively human innovation. Spatial transcriptome analysis found that these specialized OPCs engage adjacent neural progenitors (outer radial glia) via synaptic-adhesion signaling during neurogenetic period. These findings demonstrate that this coupled spatiotemporal rewiring establishes novel developmental microenvironments, providing a discrete molecular engine for human cortical evolution.

genomics↗

bioRxiv2025

Human-specific NOTCH2NL promotes astrogenesis by expanding proliferative glial progenitor states

The human cerebral cortex contains an unusually large number of glial cells, particularly astrocytes, yet the developmental and genetic mechanisms underlying their expansion remain poorly understood. While human-specific genes have been shown to promote neuronal production during cortical development, whether such genes also regulate gliogenesis has remained unclear. Here, we identify a previously unrecognized role for the human-specific gene family NOTCH2NL in promoting astrocyte-lineage expansion. Reanalysis of human fetal single-cell transcriptomic datasets revealed that NOTCH2NL is robustly expressed along the gliogenic trajectory, from glial intermediate progenitor cells to astrocytes. Functional perturbations in a human astrocyte culture system demonstrated that NOTCH2NL is both required and sufficient for astrocyte proliferation. In vivo overexpression of NOTCH2NLB in the developing mouse cortex shifted progenitor output toward the astrocyte lineage, increasing the astrocyte-to-neuron ratio from the early postnatal period through adulthood. This phenotype was associated with an expansion of proliferative glial progenitors around birth. Single-nucleus transcriptomic profiling further showed that NOTCH2NLB suppresses neuronal gene programs while activating transcriptional modules related to cell proliferation and cellular homeostasis during gliogenesis. Together, these findings indicate that human-specific NOTCH2NL acts at a conserved developmental decision point to amplify astrocyte production. Our study extends the function of NOTCH2NL beyond neurogenesis and suggests that human lineage-specific gene duplications can modulate gliogenesis, providing a developmental mechanism that may have contributed to the coordinated expansion of neuronal and glial populations in the human cortex.

developmental biology↗

bioRxiv2023

Low-CO2 inducible bestrophins in diatom thylakoid membranes sustain high photosynthetic efficacy at distant locations from the pyrenoid

Anion transporters are important to sustain a variety of physiological states in cells. Bestrophins are a family of Cl- and/or HCO3- transporters conserved in bacteria, animals, algae, and plants. Recently, bestrophin paralogs were found in the green alga Chlamydomonas reinhardtii as up- regulated components in low CO2 conditions that play an essential role in the CO2- concentrating mechanism (CCM). Bestrophin orthologs are also conserved in diatoms, a group of secondary endosymbiotic algae harboring red-type plastids, but their physiological functions are not known yet. Here, we characterized the subcellular localization and expression profile of bestrophins in the marine diatoms Phaeodactylum tricornutum (PtBST1-4) and Thalassiosira pseudonana (TpBST1 and 2). PtBST1 and PtBST2 were localized at the stromal thylakoid membrane outside of the pyrenoid, and PtBST3 was localized in the pyrenoid. Contrarily, TpBST1 and TpBST2 were both localized in the pyrenoid. These bestrophin proteins were accumulated in cells grown in atmospheric CO2 but not in 1% CO2-grown cells. To assess the physiological functions, we generated knock-out mutants for PtBST1 by genome editing. The lack of PtBST1 decreased affinity of photosynthesis for dissolved inorganic carbon closer to that of the cells grown in 1% CO2. Additionally, non-photochemical quenching was 1.5-2.0 times higher in the mutants than that of the wild type cells. These data suggests that HCO3- transport at the stroma thylakoid membranes by PtBST1 is a critical part of the CO2 evolving system of the pyrenoid in the fully induced CCM, and simultaneously that PtBST1 modulates photoprotection in response to CO2 availability in P. tricornutum. Significant statementMarine diatoms are responsible for nearly half of oceanic primary production, owing to the high-affinity photosynthesis for dissolved inorganic carbon which is supported by CO2- concentrating mechanism (CCM). This study uncovered that a bestrophin family protein at the stoma thylakoid membrane operates to import HCO3- to the thylakoid lumen and mobilizes it towards the CO2 evolving system at the pyrenoid-penetrating thylakoid in the diatom Phaeodactylum tricornutum. This HCO3- collecting system not only enhances the CCM but also down regulates the photoprotection capacity of photosystem II, presumably by affecting the thylakoid lumen acidification. This study experimentally demonstrates the molecular mechanism how diatoms optimize the use of CO2 and light energy, giving an insight into the reason of ecological successfulness of marine diatoms.

plant biology↗