Spijkerman Elly, Barua Deepak, Gerloff-Elias Antje, Kern Jürgen, Gaedke Ursula, Heckathorn Scott A
Department of Ecology and Ecosystem Modelling, University of Potsdam, Am Neuen Palais 10, Potsdam, Germany.
Extremophiles. 2007 Jul;11(4):551-62. doi: 10.1007/s00792-007-0067-0. Epub 2007 Apr 12.
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.
嗜酸衣藻生长在酸性采矿湖中，这里重金属浓度很高，嗜酸衣藻是该湖中占主导地位的浮游植物物种。为了研究金属对嗜酸衣藻在这些湖泊中的重要性，我们检测了在富含金属的湖水以及添加了金属（铁、锌）的人工生长培养基中培养后，嗜酸衣藻在生长、光合作用、细胞结构、热休克蛋白（Hsp）积累和金属吸附方面的反应。在富含金属的湖水和培养基中培养均导致光系统II功能大幅下降（尽管不同湖泊间无差异），但生长速率未下降（除了培养基+铁的情况）。在富含金属的湖水中培养的藻类中，小分子热休克蛋白的浓度高于在添加金属的培养基中培养的藻类，而Hsp60和Hsp70A的表达量则较低或相当。与在培养基中生长的细胞相比，在湖水中培养的藻类细胞内锌和铁的含量较低，而吸附在细胞表面的金属含量较高。结果表明，高锌或高铁水平可能不是采矿湖初级生产力低的主要或唯一原因，嗜酸衣藻的多种适应性变化（如高水平的热休克蛋白、减少的金属积累）增强了其对金属的耐受性，使其能够在这种不利的环境条件下生存。据推测，湖水中存在的主要压力因素是低磷和高铁浓度之间的相互作用。
