Electron microscopical observations of leaf ferritin from iron-treated Xanthium plants: Localization and diversity in the organelle

Increased ferritin quasicrystalline inclusions were obtained in Xanthium pensylvanicum leaves by a method of "iron treatment" applied to the cocklebur plants. Clusters ca. 0.5 μ in diameter of inherent electron dense particles consisting of the iron cores of ferritin (50-60 Å diameter) were observed electron microscopically in plastids and mature chloroplasts. In addition to the commonly occurring plastidal ferritin, some cytoplasmic (lipoidal) globules have been shown to contain scattered particles. In some cases the chloroplast bearing this inclusion demonstrates changes in the external shape and alterations from the normal contour. Additional aspects of the aggregate and its function are discussed.