Hyperaccumulation of Elements in Marine Organisms

High accumulation of manganese by a giant clam Tridacna squamosa

The genus Tridacna live in a coral reef of tropical and subtropical zones. High concentrations of transition elements like Mn, Ni, Zn，etc. are contained in the kidney.
From light and electron microscopic observation, many intracellular granules (10-20μm　in a diameter) with concentric layered-structure are present in the kidney tissues. It was concluded that the high Mn concentration in the kidney resulted from the presence of Mn-rich granules.

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Light　micrograph of the kidney lumen
（Intracellular granules are observed in cells)

Granules isolated from kidney tissues
(Granules have a spherical shape)

Granules of the genus Tridacna are formed in cells. The concentration and chemical form of Mn in kidney granules will be explained in the next item of Cyclosunetta menstrualis.

The biological functions and formation process of intracellular granule are under investigation.

TEM image inside of a granule
(A concentric layered-structure is observed)

｜High accumulation of metals by Bryopsis maxima｜High accumulation of vanadium by a fan worm Pseudopotamilla occelata｜
｜ High accumulation of manganese by a giant clam Tridacna squamosa｜
｜High accumulation of manganese by a marine bivalve Cyclosunetta menstrualis｜High accumulaton of iodine by a strawberry conch shell Strombus luhuanus｜
｜ High accumulation of iron by teeth of mollusks｜High accumulation of metals by an octopus Octopus vulgaris｜

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