title: Increased resistance to Cd(II) in the primitive red algae Cyanidioschyzon merolae.
abstract: Growth of Cyanidioschyzon merolae was inhibited depending on the cadmium(II) concentration in the culture medium. Although a lower level (0.01 mM) of Cd(II) inhibited growth by a factor of 0.5, higher levels (0.1 and 1 mM) induced lag periods of 10-14 days. Algal cells pretreated with 1 mM Cd(II) for 27 days grew steadily in 1 mM Cd(II) without the lag period, demonstrating that the cells became Cd(II) resistant (CdR). Cells remained resistant after four cycles (7 days per cycle) of washing and re-growing in medium without Cd(II), while intracellular Cd(II) decreased to undetectable levels. These results suggest that the Cd(II)-resistant phenotype is heritable. This phenomena may be attributable to the presence of genetic inhomogeneity in the wild-type cell populations or to mutagenesis caused by Cd(II) stress. Intracellular Cd(II) levels significantly decreased in the CdR phenotype compared to the wild-type cells, indicating that resistant cells may have a defective gene that codes for Cd(II)-uptake protein or the ability to secrete Cd(II).
authors.affiliation: Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113-8657, Japan.
authors.forename: Tomoo
authors.initials: T
authors.lastname: Shirabe
authors.forename: Mariko
authors.initials: M
authors.lastname: Omura
authors.forename: Yuko
authors.initials: Y
authors.lastname: Osaki
authors.forename: Etsuro
authors.initials: E
authors.lastname: Yoshimura
mesh_terms: D001692:Biological Transport; D002104:Cadmium / Q000633:toxicity*; D004351:Drug Resistance / Q000502:physiology; D000461:Rhodophyta / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium