Biology subjects

Chan, F.-Y.

Publications and source records attributed to Chan, F.-Y..

3 recordsLinked to original sources

bioRxiv2026

High-speed atomic force-Raman microscopy

A comprehensive understanding of the mechanisms underlying biological systems requires correlative analysis of multiple complementary molecular properties through multidimensional measurements. High-speed atomic force microscopy (HS-AFM) is a powerful tool for elucidating biomolecular structural dynamics at the single-molecule level with high spatiotemporal resolution. However, structural information alone is often insufficient for fully understanding the biological function mechanisms. Here, we report high-speed atomic force-Raman microscopy (HS-AFRM), which enables multimodal measurements combining video-rate structural imaging with chemical-bond analysis. Raman spectroscopy is a powerful, non-invasive technique that probes molecular vibrations to provide chemical information. We achieved several key technical developments that facilitated the seamless integration of HS-AFM and micro-Raman spectroscopy, allowing reliable correlative measurements of structural and chemical information. We validated the versatility of the developed system using representative samples, including two-dimensional materials and a protein. Furthermore, we demonstrate probing of changes in the surrounding environment, which are inaccessible by HS-AFM alone. Multimodal measurements incorporating fluorescence spectroscopy were also demonstrated as an additional practical extension. This multimodal approach substantially enhances the analytical capability of HS-AFM, providing a powerful platform for revealing correlated structural and chemical properties across diverse research fields.

biophysics↗

bioRxiv2026

Apical spectrin organizes cortical actin filament bundles to pattern C. elegans cuticle ridges

The apical extracellular matrix can form elaborate three-dimensional structures on animal surfaces. To better understand the mechanisms that pattern and shape these structures, we focus on development of collagen-rich cuticle ridges (alae) in adult C. elegans. Previous studies suggested that longitudinal actin filament bundles (AFBs) in the lateral seam epidermis specify alae position through a mechanism that involves post-secretory matrix delamination. Here we identify additional components of this highly organized cortical actin network and show that loss of the apical {beta}H-spectrin SMA-1 specifically disrupts organization of the two AFBs that would normally flank the site where the middle alae ridge forms. Correspondingly, sma-1 loss, or mutation of its actin binding domains, also disrupts formation of the middle alae ridge. Ultrastructurally, sma-1 mutants have expanded regions of matrix delamination that can explain middle ridge loss. Together, these data highlight the importance of apical spectrin for organizing a patterned actin network within epithelia and show that, via its effects on actin organization, spectrin can also change the extracellular matrix and its patterns on animal surfaces.

developmental biology↗

bioRxiv2022

Anillin forms linear structures and facilitates furrow ingression after septin and formin depletion

During cytokinesis a contractile ring consisting of unbranched filamentous actin (F-actin) and myosin II filaments assembles and constricts at the cell equator. Unbranched F-actin is de novo generated by formin and without formin cleavage furrow ingression fails. In C. elegans depletion of septin restores cleavage furrow ingression in formin (CYK-1) mutants. How the cleavage furrow ingresses without a detectable unbranched F-actin ring is not known. We report, that in this setting anillin (ANI-1) is essential for furrow ingression and forms a meshwork of linear structures, which circumferentially align around the cell equator. Although equatorial ANI-1 recruitment is facilitated by septins, the formation of linear ANI-1 structures is septin independent. Analysis of ANI-1 deletion mutants reveals that its disordered linker region is required for linear structure formation and furrow ingression. We also found that myosin II (NMY-2) decorates linear ANI-1 structures and promotes their circumferential alignment. NMY-2 also interacts with various lipids and forms membrane localized clusters in absence of F-actin and anillin binding. This suggests that NMY-2 represents an independent link between the F-actin / ANI-1 network and the plasma membrane. Collectively, our data reveals a compensatory mechanism, mediated by ANI-1 linear structures and membrane-bound NMY-2, that promotes furrow formation and ingression when formins are depleted and therefore unbranched F-actin polymerization is compromised.

cell biology↗