Peña-Castro Julián Mario, Martínez-Jerónimo Fernando, Esparza-García Fernando, Cañizares-Villanueva Rosa Olivia
Laboratorio de Biotecnología de Microalgas, Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional. Ave. IPN 2508, San Pedro Zacatenco, México DF 07360, Mexico.
Chemosphere. 2004 Dec;57(11):1629-36. doi: 10.1016/j.chemosphere.2004.06.041.
The microalgae genus Scenedesmus is commonly found in freshwater bodies, wastewater facilities and water polluted with heavy metals. Phenotypic plasticity in Scenedesmus has been documented in response to a wide variety of conditions; however, heavy metals have not been comprehensively documented as phenotypic plasticity inducers. In this study, we report the phenotypic plasticity of Scenedesmus incrassatulus (a non-spiny, four-cell coenobium forming species) in response to EC(50) value of copper, cadmium and hexavalent chromium. S. incrassatulus was grown in batch cultures in the presence of each metal. Chlorophyll-a content, cell size, parameters derived from the schematic energy-flux model for photosystem II, and morphotype expressions were recorded. Divalent cation metals induced unicellular forms, and hexavalent chromium produced out-of-shape coenobia corresponding to various stages of autospore formation. The changes induced by divalent metals were interpreted as phenotypic plasticity, because they were always associated to population doublings and were reversible when toxicant pressure was removed (only for Cu). Copper was the best inductor of unicellular forms and also affected significantly all the photosynthetic parameters measured. The developed morphotypes could confer ecological advantages to S. incrassatulus in metal stressed environments.
栅藻属微藻常见于淡水水体、污水处理设施以及受重金属污染的水体中。已记录到栅藻对多种条件具有表型可塑性；然而，重金属作为表型可塑性诱导剂尚未得到全面记录。在本研究中，我们报告了厚壁栅藻（一种不具刺、形成四细胞群体的物种）对铜、镉和六价铬的半数效应浓度（EC50）值的表型可塑性。厚壁栅藻在每种金属存在的情况下进行分批培养。记录叶绿素a含量、细胞大小、源自光系统II示意能量通量模型的参数以及形态型表达。二价阳离子金属诱导单细胞形态，六价铬产生对应于不同阶段自孢子形成的畸形群体。二价金属诱导的变化被解释为表型可塑性，因为它们总是与种群倍增相关，并且在去除毒物压力时是可逆的（仅针对铜）。铜是单细胞形态的最佳诱导剂，并且对所有测量的光合参数也有显著影响。所形成的形态型可能赋予厚壁栅藻在金属胁迫环境中的生态优势。
