Gallego Andrea, Martín-González Ana, Ortega Ruth, Gutiérrez Juan C
Departamento de Microbiología-III, Facultad de Biología, Cl. Jose Antonio Novais 2, Universidad Complutense, 28040 Madrid, Spain.
Chemosphere. 2007 Jun;68(4):647-61. doi: 10.1016/j.chemosphere.2007.02.031. Epub 2007 Mar 29.
In the present study, we have assessed by flow cytometry, the cytotoxicity of the heavy metals Cd, Zn and Cu on populations of the ciliated protozoan Tetrahymena thermophila. The obtained LC(50) for these metals was estimated as 0.195mgCdl(-1), 3.58mgZnl(-1) and 0.47mgCul(-1), respectively. As a result, the toxicity rank for this eukaryotic microorganism is Cd>Cu>>Zn. Using the same methodology and the Concentration Addition approach, the toxicity of binary mixtures of these metals was evaluated in order to detect the type of interaction between these metals. Results indicated that antagonism is the predominant interaction but it can change to additivity or even to synergism at high metal concentrations. Besides, the concentration ratio between metals plays also a crucial role in determining the type of metallic interaction, at least in Tetrahymena. Cytotoxicity data from single and bimetallic mixtures have been compared with those from selected microalgae, other species of ciliates, fish and mammalian cell lines and metazoan. By other hand, we have detected the mitochondrial generation of peroxides induced by both single and binary treatments with Cd, Zn and Cu on populations of Tetrahymena, using the specific fluorophore dyhidrorhodamine. The nature and concentrations of metal as well as the metallic ratio were important factors in reactive oxygen species production. All results found in T. thermophila are compared with previous reports in other organisms and, some explanations and hypothesis to support results are given, including the involvement of metallothioneins as antioxidants and their role in the binding of metal cations.
在本研究中，我们通过流式细胞术评估了重金属镉（Cd）、锌（Zn）和铜（Cu）对嗜热四膜虫纤毛原生动物群体的细胞毒性。这些金属的半数致死浓度（LC(50)）分别估计为0.195mgCd l(-1)、3.58mgZn l(-1)和0.47mgCu l(-1)。因此，这种真核微生物的毒性等级为Cd>Cu>>Zn。使用相同的方法和浓度相加法，评估了这些金属二元混合物的毒性，以检测这些金属之间的相互作用类型。结果表明，拮抗作用是主要的相互作用，但在高金属浓度下可能会转变为相加作用甚至协同作用。此外，金属之间的浓度比在确定金属相互作用类型方面也起着关键作用，至少在四膜虫中是这样。已将单金属和双金属混合物的细胞毒性数据与选定的微藻、其他纤毛虫物种、鱼类和哺乳动物细胞系以及后生动物的数据进行了比较。另一方面，我们使用特异性荧光团二氢罗丹明检测了镉、锌和铜对四膜虫群体进行单处理和二元处理所诱导的线粒体过氧化物生成。金属的性质和浓度以及金属比例是活性氧产生的重要因素。将嗜热四膜虫中的所有结果与其他生物体的先前报告进行了比较，并给出了一些支持结果的解释和假设，包括金属硫蛋白作为抗氧化剂的参与及其在结合金属阳离子中的作用。
