X-ray microanalysis of phytoferritin in Constantinea (Cryptonemiales, Rhodophyta)

Abstract
Particles characterized by an electron-dense core, 5-7 nm in diameter, form crystalline aggregations in chloroplasts of senescing blades of Constantinea simplex and C. subulifera. The native electron density of the particle core suggests the presence of a heavy metal. Earlier tentative identification of the particles as phytoferritin is now confirmed by X-ray microanalysis, which gives direct proof of the presence of Fe in the particles.