Secretory ferritins mediate iron delivery during magnetite tooth formation in chitons

Secretory ferritin subunits in chiton radular tissue are linked to iron delivery during magnetite tooth formation, with Ag-loaded hemolymph ferritin transferring Ag to developing teeth.

• Why it matters: Iron must be tightly regulated because unbound iron is toxic, yet chitons build magnetite-mineralized teeth using extreme iron accumulation whose supply route was unclear.
• What they did: Synchrotron X-ray fluorescence mapping tracked iron redistribution from radular epithelium to developing teeth, while integrated transcriptomics/proteomics identified secretory ferritin subunits expressed in the midgut gland and present in hemolymph.
• The result: In vivo fluorescence tracking showed circulating ferritin is selectively taken up by radular epithelium, and Ag-loaded hemolymph ferritin injection led to Ag detection in developing teeth, supporting midgut gland–to–hemolymph–to–radula iron transport.