title: Relief of arsenate toxicity by Cd-stimulated phytochelatin synthesis in the green alga Chlamydomonas reinhardtii.
abstract: In most photosynthetic organisms, inorganic arsenic taken up into the cells inhibits photosynthesis and cellular growth. In a green alga, Chlamydomonas reinhardtii, 0.5 mM arsenate inhibited photosynthesis almost completely within 30 min. However, in cells acclimated with a sublethal concentration (0.05 to 0.1 mM) of Cd, the inhibition of photosynthesis at 30 min after the addition of arsenate was relieved by more than 50%. The concentrations of arsenic incorporated into the cells were not significantly different between the Cd-acclimated and the non-acclimated cells. The Cd-acclimated cells accumulated Cd and synthesized phytochelatin (PC) peptides, which are known to play an important role in detoxification of heavy metals in plants. By the addition of an inhibitor of glutathione (an intermediate in the PC biosynthetic pathway) biosynthesis, buthionine sulfoximine, cells lost not only Cd tolerance but also arsenate tolerance. These results suggest that glutathione and/or PCs synthesized in Cd-acclimated cells are involved in mechanisms of arsenate tolerance.
authors.affiliation: School of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Kobayashi
authors.forename: Shoko
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Saegusa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Inouhe
authors.forename: Hiroko
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Mikio
authors.initials: M
authors.lastname: Tsuzuki
mesh_terms: D000818:Animals; D001149:Arsenates / Q000378:metabolism / Q000633:toxicity*; D001151:Arsenic / Q000032:analysis; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002104:Cadmium / Q000032:analysis / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D016825:Chlamydomonas reinhardtii / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology*; D005978:Glutathione / Q000096:biosynthesis* / Q000187:drug effects / Q000378:metabolism; D008658:Inactivation, Metabolic / Q000502:physiology; D010788:Photosynthesis / Q000187:drug effects; D054811:Phytochelatins; D013997:Time Factors
chemical_list: D001149:Arsenates; D002104:Cadmium; D019328:Buthionine Sulfoximine; D054811:Phytochelatins; D005978:Glutathione; D001151:Arsenic; C025657:arsenic acid