Biological uptake of Cd, Se(IV) and Zn by Chlamydomonas reinhardtii in response to different phosphate and nitrate additions
Biological uptake of Cd, Se(IV) and Zn by Chlamydomonas reinhardtii in response to different phosphate and nitrate additions
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DOI：
10.3354/ame035163
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发表时间：
2004-04
影响因子：
1.4
通讯作者：
R. Yu;Wen-Xiong Wang
中科院分区：
文献类型：
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作者：
R. Yu;Wen-Xiong Wang
研究了不同营养条件对淡水绿藻Cd、Zn和Se(IV)在4h暴露时间内积累的影响。细胞在不同的介质(缓冲液、碱性和简化吸收介质)中适应不同环境磷水平(0.1~10.0µM)2d后，细胞内金属离子浓度增加3.6~14倍(Cd)和1.6~4.0倍(Zn)。然而，硒的吸收却下降了7.7倍至44倍。半连续培养实验进一步证明，在相同的磷水平下，藻类中Cd的金属浓度提高了26倍，锌的浓度提高了8.0倍，而Se的积累被抑制了75倍。随着磷浓度的增加，半连续培养对Cd的吸收速率提高了269倍，对锌的吸收速率增加了11倍，而对Se的吸收降低了92倍。添加适量磷也显著增加了Cd和Zn的胞内分配，但对Se的影响不明显。对于缺磷或缺磷的细胞，富磷培养基比缺磷培养基能显著增加细胞对Cd和Zn的积累。磷饥饿细胞对Cd和Zn的摄取激增。缺磷还显著增加了缺磷培养基中Se的积累。N肥在5~200µM范围内显著增加了藻类对Cd和Zn的吸收和细胞内分配，尽管这种影响不是严格的浓度依赖关系。我们的研究有力地表明，环境中磷的富集会极大地促进Cd和Zn的积累和封存，这可能是由于细胞中快速的P吸收和随后形成的聚磷酸盐，而明显抑制吸收可能是由于Se和P之间竞争类似的阴离子形式来运输。
We investigated the influences of different nutrient regimes on the accumulation of Cd, Zn, and Se(IV) in the freshwater green alga Chlamydomonas reinhardtii over a 4 h exposure period. After the cells had been acclimated to different ambient P levels from 0.1 to 10.0 µM for 2 d in differ- ent media (buffer, basic and simplified uptake media), their intracellular metal concentrations increased by 3.6 to 14× for Cd and 1.6 to 4.0× for Zn. Se uptake was, however, decreased by 7.7 to 44× . Semi-continuous culture experiments further demonstrated that the alga's metal concentrations were enhanced 26× for Cd and 8.0× for Zn, whereas Se accumulation was inhibited 75× at the same medium P levels. The uptake rates in semi-continuous cultures increased by 269× for Cd and 11× for Zn, but Se uptake decreased 92× with increasing P concentration. Medium P additions also signifi- cantly increased intracellular partitioning for Cd and Zn, but there was no apparent effect for Se. For P-starved or P-repleted cells, the P-enriched medium dramatically increased the cellular accumula- tion of Cd and Zn compared with the P-depleted medium. A surge uptake of Cd and Zn occurred in P-starved cells. P starvation also resulted in a remarkable increase in Se accumulation in the P- deplete medium. N enrichment from 5 to 200 µM significantly increased the alga's uptake and intra- cellular partitioning for Cd and Zn, although the effects were not strictly concentration-dependent. Our study strongly suggests that ambient P enrichment greatly stimulates Cd and Zn accumulation and sequestration in C. reinhardtii, presumably due to rapid P uptake and subsequent formation of polyphosphate in the cells, and distinctly inhibits Se uptake possibly due to the competition of similar anionic forms for transport between Se and P.