Cytoplasmic silicon in the centric diatom Thalassiosira pseudonana localized by electron spectroscopic imaging

Silicon and phosphorus distributions in the cytoplasm of the diatom Thalassiosira pseudonana were mapped separately using electron spectroscopic imaging techniques. The phosphorus profile delineating cytoplasmic ribosomes overlapped the silicon profile with a high degree of coincidence suggesting a silicon–ribosomal association. Lipid inclusions were also sites of silicon accumulation. The possible significance of these results in wall biomineralization is discussed.