Champelovier, D. | Search bioRxiv

bioRxiv2026

Pdgfrβ signaling orchestrates meningeal repair via the mobilization of arachnoid cells.

Zebrafish possess remarkable regeneration abilities, including the capacity to repair their central nervous system (CNS). Leveraging the optical accessibility of the zebrafish brain, we investigated the mechanisms underlying meningeal repair following laser-induced brain injuries to the optic tectum. In previous work, using live imaging of laser-induced surface injuries to the optic tectum in juvenile zebrafish, we identified a population of flat PDGFR{beta}+ cells that rapidly migrate to the wound site and contribute to meningeal repair. Here, using pharmacological inhibition or genetic perturbation of PDGFR{beta}, we show that recruitment of these PDGFR{beta}+ meningeal cells is strongly dependent on PDGFR{beta} signaling, unlike recruitment of PDGFR{beta}+ pericytes deeper in the wound. Furthermore, PDGFR{beta} inhibition diminishes neurite regrowth and macrophage recruitment. Using photoconversion assays, we traced the origin of PDGFR{beta}+ meningeal cells that migrated to the wound in response to injury, in the midbrain-forebrain and midbrain-hindbrain sulci. Our findings highlight PDGFR{beta}s pivotal role in orchestrating meningeal repair and reveal novel cellular dynamics during CNS regeneration. These results provide insights into potential therapeutic strategies for enhancing brain repair and mitigating fibrosis in mammals, where meningeal scarring remains a barrier to CNS regeneration. HighlightsPDGFR{beta} signaling orchestrates the rapid accumulation of meningeal cells at CNS injury sites to drive tissue remodeling. PDGFR activity acts as a critical regulator, co-recruiting PDGFR{beta}+ meningeal cells and mfap4+ macrophages to the lesion. Meningeal cells are essential for neural repair, with PDGFR inhibition leading to significantly reduced neurite density. Zebrafish maintain locomotor resilience post-injury, identifying a clear distinction between meningeal-driven axonal regrowth and basic motor circuitry recovery. Establishes a high-resolution zebrafish platform to identify conserved meningeal targets for mammalian CNS regeneration.

cell biology↗

bioRxiv2024

Root Expansion Microscopy (ROOT-ExM): A streamlined super resolution method for plants

Expansion microscopy (ExM) has revolutionized biological imaging by physically enlarging samples, surpassing the light diffraction limit and enabling nanoscale visualization using standard microscopes. While extensively employed across a wide range of biological samples, its application to plant tissues is sparse. In this work, we present ROOT-ExM, an expansion method suited for stiff and intricate multicellular plant tissues, focusing on the primary root of Arabidopsis thaliana. ROOT-ExM achieves isotropic expansion with a fourfold increase in resolution, enabling super-resolution microscopy comparable to STimulated Emission Depletion (STED) microscopy. Labelling is achieved through immunolocalization, compartment-specific dyes, and native fluorescence preservation, while N-Hydroxysuccinimide (NHS) ester-dye conjugates reveal the ultrastructural context of cells alongside specific labelling. We successfully applied ROOT-ExM to image various cellular structures, including the Golgi apparatus, the endoplasmic reticulum, the cytoskeleton, and wall-embedded structures such as plasmodesmata. When combined with lattice light sheet microscopy (LLSM), ROOT-ExM achieves 3D quantitative analysis of nanoscale cellular process, revealing increased vesicular fusion in close proximity of the cell plate during cell division. Achieving super-resolution fluorescence imaging in plant biology remains a formidable challenge. Our findings underscore that ROOT-ExM provides a remarkable, cost-effective solution to this challenge, paving the way for unprecedented insights into plant cellular subcellular architecture. One sentence summaryROOT-ExM achieves super-resolution expansion microscopy in plants

plant biology↗