Stress responses and metal tolerance of Chlamydomonas acidophila in metal-enriched lake water and artificial medium.
Chlamydomonas acidophila faces high heavy-metal concentrations in acidic mining lakes, where it is a dominant phytoplankton species. To investigate the importance of metals to C. acidophila in these lakes, we examined the response of growth, photosynthesis, cell structure, heat-shock protein (Hsp) accumulation, and metal adsorption after incubation in metal-rich lake water and artificial growth medium enriched with metals (Fe, Zn). Incubation in both metal-rich lake water and medium caused large decreases in photosystem II function (though no differences among lakes), but no decrease in growth rate (except for medium + Fe). Concentrations of small Hsps were higher in algae incubated in metal-rich lake-water than in metal-enriched medium, whereas Hsp60 and Hsp70A were either less or equally expressed. Cellular Zn and Fe contents were lower, and metals adsorbed to the cell surface were higher, in lake-water-incubated algae than in medium-grown cells. The results indicate that high Zn or Fe levels are likely not the main or only contributor to the low primary production in mining lakes, and multiple adaptations of C. acidophila (e.g., high Hsp levels, decreased metal accumulation) increase its tolerance to metals and permit survival under such adverse environmental conditions. Supposedly, the main stress factor present in the lake water is an interaction between low P and high Fe concentrations.
Spijkerman
Elly
E
Department of Ecology and Ecosystem Modelling, University of Potsdam, Am Neuen Palais 10, Potsdam, Germany. spijker@uni-potsdam.de
Barua
Deepak
D
Gerloff-Elias
Antje
A
Kern
Jürgen
J
Gaedke
Ursula
U
Heckathorn
Scott A
SA
D000222:Adaptation, Physiological; D000818:Animals; D001692:Biological Transport; D018834:Chaperonin 60 / Q000378:metabolism; D002696:Chlamydomonas / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D005618:Fresh Water / Q000737:chemistry; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D050888:Heat-Shock Proteins, Small / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis / Q000633:toxicity*; D010758:Phosphorus / Q000032:analysis; D010788:Photosynthesis / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000378:metabolism; D013312:Stress, Physiological / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*; D015032:Zinc / Q000032:analysis / Q000633:toxicity*
D018834:Chaperonin 60; D003470:Culture Media; D018840:HSP70 Heat-Shock Proteins; D050888:Heat-Shock Proteins, Small; D045332:Photosystem II Protein Complex; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D007501:Iron; D015032:Zinc