Effects of Metal Combinations on the Production of Phytochelatins and Glutathione by the Marine Diatom Phaeodactylum tricornutum Article Received: 21 February 2005 Accepted: 06 April 2005 DOI:
Cite this article as: Kawakami, S.K., Gledhill, M. & Achterberg, E.P. Biometals (2006) 19: 51. doi:10.1007/s10534-005-5115-6 Abstract
Copper, Cd and Zn can be found at elevated concentrations in contaminated estuarine and coastal waters and have potential toxic effects on phytoplankton species. In this study, the effects of these metals on the intracellular production of the polypeptides phytochelatin and glutathione by the marine diatom
Phaeodactylum tricornutum were examined in laboratory cultures. Single additions of Cu and Cd (0.4 μM Cu 2 and 0.45 μM Cd 2+) to the culture medium induced the production of short-chained phytochelatins (( γ-Glu-Cys) -Gly where n n = 2–5), whereas a single addition of Zn (2.2 μM Zn 2+) did not stimulate phytochelatin production. Combination of Zn with Cu resulted in a similar phytochelatin production compared with a single Cu addition. The simultaneous exposure to Zn and Cd led to an antagonistic effect on phytochelatin production, which was probably caused by metal competition for cellular binding sites. Glutathione concentrations were affected only upon exposure to Cd (85% increase) or the combination of Cd with Zn (65% decrease), relative to the control experiment. Ratios of phytochelatins to glutathione indicated a pronounced metal stress in response to exposures to Cu or Cd combined with Zn. This study indicates that variabilities in phytochelatin and glutathione production in the field can be explained in part by metal competition for cellular binding sites. Keywords glutathione metal toxicity metal stress Phaeodactylum tricornutum phytochelatins thiols References Ahner, BA, Kong, S, Morel, FMM 1995 Phytochelatin production in marine-algae. 1. An Interspecies Comparison Limnol Oceanogr 40 649 657 Google Scholar Ahner, BA, Morel, FMM 1995 Phytochelatin production in marine-algae 2. Induction by various metals Limnol Oceanogr 40 658 665 Google Scholar Ahner, BA, Wei, LP, Oleson, JR, Ogura, N 2002 Glutathione and other low molecular weight thiols in marine phytoplankton under metal stress Mar Ecol Prog Ser 232 93 103 Google Scholar Cid, A, Herrero, C, Torres, E, Abalde, J 1995 Copper toxicity on the marine microalga Phaeodactylum tricornutum – effects on photosynthesis and related parameters Aquat Toxicol 31 165 174 CrossRef Google Scholar Cobbett, CS 2000 Phytochelatins and their roles in heavy metal detoxification Plant Physiol 123 825 832 CrossRef PubMed Google Scholar Croot, PL, Moffett, JW, Brand, LE 2000 Production of extracellular Cu complexing ligands by eucaryotic phytoplankton in response to Cu stress Limnol Oceanogr 45 619 627 Google Scholar
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