DESPITE their diet of algae, chiton molluscs have the hardest teeth known – and a new atom-probe study is helping us figure out how they grow.
The chiton’s black, metallic teeth are made of magnetite, an iron oxide used in electronics and medical devices. Making magnetite often requires high temperature, pressure or acidity – but the chiton does it in its mouth. The question was, how?
Over five years, Lyle Gordon at Northwestern University in Evanston, Illinois, and colleagues have used an atom probe to study the teeth of a fingernail-sized chiton mollusc. The probe plucks charged atoms from a material one at a time, ultimately giving a detailed view inside it.
They found that, in the watery gel at a tooth’s centre, proteins and sugars criss-cross to form a scaffold that binds positively charged ions such as magnesium and sodium. Those ions, Gordon suspects, then bind negatively charged proteins that collect iron, providing a complex template for the growing tooth’s shell.
Better knowledge of chiton biology could spur manufacturing, says David Bell of Harvard University, who was not involved in the work. “It could be a revolutionary way to produce things.”
This article appeared in print under the headline “How to grow the hardest teeth in the sea”
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