Biology subjects

Sutter, S. M.

Publications and source records attributed to Sutter, S. M..

2 recordsLinked to original sources

bioRxiv2026

Directional bone matrix mineralization in the CAM assay is governed by vascular integration and matrix remodeling

Bone matrix mineralization plays an important role in maintaining bone health but is a highly dynamic process for which few physiologically relevant model systems exist. The chorioallantoic membrane (CAM) assay is one such assay and has been used to study biomineralization; however, the mechanisms controlling mineral deposition in the CAM assay remain poorly understood. Here, we implanted decellularized, organic bone matrices onto the CAM and investigated their mineralization using a combination of micro-computed tomography, Raman spectroscopy, scanning electron microscopy, and histochemistry. These studies revealed increased mineralization and microvessel density on the shell-facing interface of the implanted matrices, while their embryo-facing counterpart lacked mineralization but was densely infiltrated by cells. Seeding organic bone matrices with mesenchymal stromal cells (MSCs) prior to CAM-implantation prevented mineralization by altering matrix micro- and nanostructure and limiting vessel integration. Collectively, our results suggest that mineral precursors from the eggshell and vasculature combine to mineralize organic bone matrix in the CAM assay, while proteolytic remodeling by invaded or implanted stromal cells inhibits that process. Our findings provide critical new insights into the interplay between acellular and cellular drivers of bone matrix mineralization, and will inform future studies of biomineralization using the CAM assay.

bioengineering↗

bioRxiv2025

A multiscale physicochemical characterization of melanin-based feather coloration in the rapid Capuchino Seedeater radiation

Melanin-based plumage coloration in birds is shaped by pigment composition as well as melanosome morphology and distribution, however, the ways in which these factors together modulate observable color remain poorly understood. We investigate this relationship in the Capuchino Seedeaters (genus Sporophila), whose recent, rapid radiation driven by sexual selection resulted in 12 species with diverse coloration patterns. Using scanning electron microscopy (SEM) and micro-computed tomography ({micro}CT), combined with a novel application of Fontana-Masson stain to image melanosomes at high resolution, we characterize melanosome distribution and morphology in several variably colored plumage patches across Capuchino species. Melanosome morphologies followed patch-specific patterns that did not directly correlate with coloration: crown feather melanosomes were larger, more elongated, and had greater percent eumelanin content than those in belly, throat, or dorsum/rump patches. We also observed that dorsal patches had more total melanin than ventral ones, with pigment and coloration patterns suggesting possible signaling and photoprotective roles. More generally, we show how the patch-specific coloration of male Capuchinos is accompanied by differences in melanosome morphology and melanin composition and abundance. Our work highlights the challenges that remain in understanding how the nanoscale mechanisms of melanin-based pigmentation translate into macroscale plumage coloration.

evolutionary biology↗