2025/08/01 by Chong Chen, Satoshi Okada, Hiromi Watanabe +2 · 1 voice
Materials Science · Biochemistry, Genetics and Molecular Biology · Engineering · #Silk-based biomaterials and applications #Cellular Mechanics and Interactions #Marine Biology and Environmental Chemistry
paper · doi:10.1098/rspb.2025.1220
Animals produce diverse hard structures for critical functions such as protection, feeding and detoxification. Most animals use the polysaccharide chitin as a framework for this, while vertebrates have switched to using fibrous proteins like collagen and keratin. Vertebrates make structures like skin and horns through a cellular differentiation process called keratinization where cells accumulating keratin die and compact into hard layers—drastically different from chitinous structures, which are secreted directly by living cells. Here, we report remarkable chitinous dermal sclerites that are not secreted but instead produced by a keratinization-like process, in the deep-sea hot-vent snail Ifremeria nautilei . These scales bundle to form ‘warts’ on the foot, the framework of which we show to be β-chitin. Microscopic observations reveal that Ifremeria scales are not formed by uniform, secreted layers but instead involve cells going through a series of unusual differentiation steps strongly resembling keratinization. The only other gastropod with chitinous dermal sclerites is the phylogenetically distant scaly-foot snail Chrysomallon squamiferum , but the scales of Chrysomallon form by secretion. Our finding of a chitinous convergence for keratinization opens a new avenue to unveil how such complex terminal cell differentiation processes evolve and may also inspire biomimetic innovation in material sciences.