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内容記述 |
Metal accumulation in marine invertebrates has attracted significant attention owing to its toxicity to human health. Turbo sazae are marine gastropods that inhabit rocky coastal shores and feed on algae. Although T. sazae is a major edible fish resource in Japan, metal accumulation in the soft body of T. sazae has not been examined. In this study, metal levels, distribution, chemical forms, and elemental composition in soft tissues of T. sazae were examined. Extensive iron accumulation i.e. over 10,000 µg/g dw in the digestive gland of T. sazae was detected. Moreover, X-ray absorption fine structure (XAFS) measurements revealed that ferritin, an iron storage protein, was an iron accumulator. Elemental distribution was observed using particle-induced X-ray emission with a microbeam (µ-PIXE), indicating that ferritin in the digestive gland contains phosphorus in the iron mineral core. The synchrotron radiation micro-X-ray fluorescence (SR-µXRF) measurements showed that the µm-sized brown granular cells are responsible for iron storage, with over 70,000 µg/g ww of iron accumulated at the most concentrated point. These results suggest that T. sazae contributes to the ocean’s iron cycle by grazing on iron-rich algae and rocks and storing iron using unique ferritin, which is inaccessible to many marine organisms. |
