Biology subjects

Bouchet-Marquis, C.

Publications and source records attributed to Bouchet-Marquis, C..

3 recordsLinked to original sources

bioRxiv2025

Nudibranch color diversity shares a common origin in guanine photonic structures

Nudibranchs are well known for their bright and diverse color patterns. This coloration is typically a form of aposematism, warning predators against toxic compounds sequestered from their prey and weaponized as a form of defense. Although many of the hues in nudibranchs have pigmentary origin, multilayer structures composed of guanine nano-platelets have been suggested as the source of color enhancement in the nudibranch Flabellina iodenea. Here, using a combination of white light and Raman microspectroscopy techniques, we report that such guanine-based multilayer structures are a widespread mechanism to create angular-independent structural color across the dorid and aeolid groups. Additionally, by using cryo-FIB tomography, we were able to access the complex 3D organization of the guanine nano-platelets responsible for the strong blue coloration of Chromodoris annae. We propose that the multilayer organization of guanine platelets with varying orientations across the tissue offers a particularly effective strategy for producing diverse optical effects. In this configuration, hue is mainly governed by interlayer spacing, while the angular dependence of color can be tuned through the degree of local order, allowing a single structural motif to generate a broad palette of optical appearances. Significance statementNudibranchs are an extraordinarily diverse group of marine animals, renowned for their dazzling range of colors and striking patterns. Whilst their pigmentary coloration is well understood, so far, structural coloration, obtained only by nanostructures, has only been reported in the nudibranch Flabellina iodenea. In this work, we present a comparative analysis of structural coloration across nudibranch species from both benthic and coral reef environments, and we show that guanine-based nano-structures are a common motif responsible for a wide range of colors, spanning the dorid and aeolid groups. We foresee that the 3D imaging conducted here may serve as inspiration for bio-photonics studies in other marine organisms, and that the structures themselves could serve as inspiration for bio-inspired materials.

biophysics↗

bioRxiv2024

Ribosome-Associated Vesicles promote activity-dependent local translation

Local protein synthesis in axons and dendrites underpins synaptic plasticity. However, the composition of the protein synthesis machinery in distal neuronal processes and the mechanisms for its deployment to local translation sites remain unclear. Here, we employed a multi-scale imaging approach combining cryo-electron tomography, volume electron microscopy, and live-cell imaging to identify endoplasmic reticulum-derived Ribosome-Associated Vesicles (RAVs) as a dynamic platform for moving ribosomes to distal processes and promoting activity-dependent local translation. We demonstrate that neuronal stimulation triggers compartment-specific RAV responses: dendrites accumulate stationary RAVs at sites of enhanced translation, while axons accelerate RAV transport. Real-time imaging of translation at single mRNA resolution reveals that RAVs boost local translation output compared to RAV-independent mechanisms. These findings establish RAVs as specialized platforms that integrate activity-dependent signals with local protein synthesis, providing a mechanistic framework for understanding how neurons achieve precise spatiotemporal control of protein synthesis.

neuroscience↗

bioRxiv2024

Characterization of the three-dimensional synaptic and mitochondrial nanoarchitecture within glutamatergic synaptic complexes in postmortem human brain via focused ion beam-scanning electron microscopy

Synaptic function is directly reflected in quantifiable ultrastructural features using electron microscopy (EM) approaches. This coupling of synaptic function and ultrastructure suggests that in vivo synaptic function can be inferred from EM analysis of ex vivo human brain tissue. To investigate this, we employed focused ion beam-scanning electron microscopy (FIB-SEM), a volume EM (VEM) approach, to generate ultrafine-resolution, three-dimensional (3D) micrographic datasets of postmortem human dorsolateral prefrontal cortex (DLPFC), a region with cytoarchitectonic characteristics distinct to human brain. Synaptic, sub-synaptic, and organelle measures were highly consistent with findings from experimental models that are free from antemortem or postmortem effects. Further, 3D neuropil reconstruction revealed a unique, ultrastructurally-complex, spiny dendritic shaft that exhibited features characteristic of heightened synaptic communication, integration, and plasticity. Altogether, our findings provide critical proof-of-concept data demonstrating that ex vivo VEM analysis is an effective approach to infer in vivo synaptic functioning in human brain.

neuroscience↗