Novel iron-storage particles may play a role in aluminum tolerance of Cyanidium caldarium.
Cyanidium caldarium (Tilden) Geitler, a unicellular red alga, has extraordinarily high aluminum (Al) tolerance. Algal cells cultured in the presence or absence of Al were subjected to transmission electron microscopy and energy dispersive X-ray analysis. Substantial changes to the thylakoid lumens were observed for the algal cells cultured in medium containing 200 mM Al, while other organelles were largely unaffected. Several spherical electron-dense bodies were found in the cytoplasm near the nucleus of both of the control and Al-treated cells. Although high levels of Fe and P were found in the bodies of control cells, immunocytochemical and morphological analysis data did not match the criteria established for Fe-accumulating substances like ferritin and phytate. In addition to these elements, Al was found in the bodies of the Al-treated cells. These results suggest that the electron-dense bodies function as an Fe-storage site under normal culture conditions, and that sequestration of Al in these bodies contributes to the high Al tolerance exhibited by C. caldarium.
Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Seiji
S
Nagasaka
Naoko K
NK
Nishizawa
Takashi
T
Negishi
Kenichi
K
Satake
Satoshi
S
Mori
Etsuro
E
Yoshimura
D000535:Aluminum / Q000493:pharmacokinetics*; D002478:Cells, Cultured; D004361:Drug Tolerance; D007501:Iron / Q000378:metabolism*; D008854:Microscopy, Electron; D000461:Rhodophyta / Q000502:physiology* / Q000648:ultrastructure
D000535:Aluminum; D007501:Iron