Departamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
Chemosphere. 2010 Jan;78(4):397-401. doi: 10.1016/j.chemosphere.2009.11.006. Epub 2009 Dec 3.
Copper complexation in marine systems is mainly controlled by organic matter, partially produced by micro- and macroalgae that release exudates with the capacity to bind metals. This feature is important as it influences bioavailability, bioaccumulation, toxicity, and transport of copper through biological membranes. The release of Cu-complexing ligands by seaweeds cultured under copper excess was studied in the laboratory. Five macroalgae belonging to different functional groups were used, including the filamentous Chaetomorphafirma (Chlorophyta), the foliose Ulvalactuca (Chlorophyta) and Porphyra columbina (Rhodophyta), the corticated Gelidium lingulatum (Rhodophyta), and the leathery Lessonia nigrescens (Phaeophyceae). The concentration of ligands and their copper-binding strength (logK') of exudates released by each species was determined by anodic stripping voltammetry (ASV). The selected algae released exudates in a wide range of concentration (42-117 nM) after 48h of culture, and addition of 157nM copper increased the production of ligands up to 8 times. A relationship between structural complexity or thallus thickness and the amount of ligands released was not observed. The binding strength (logK') varied among species from 7.6 to 8.9, a response that was not modified by exposure to sub-lethal copper excess. The kelp L. nigrescens showed a fast response to copper excess, releasing ligands that reduced toxicity of the metal in hours. Results suggest that intertidal and shallow subtidal macroalgae might have been overlooked regarding their role as producers of organic ligands and, therefore, as modulators of metal complexing capacity in coastal waters.
海洋系统中的铜络合主要受有机物控制，部分由微藻和海藻产生，这些藻类释放出具有结合金属能力的分泌物。这一特性很重要，因为它影响铜的生物利用度、生物积累、毒性和通过生物膜的运输。在实验室中研究了在铜过剩条件下培养的海藻释放铜络合剂的情况。使用了属于不同功能群的五种大型藻类，包括丝状 Chaetomorpha firma（绿藻）、叶状 Ulva lactuca（绿藻）和 Porphyra columbina（红藻）、皮质化 Gelidium lingulatum（红藻）和革质 Lessonia nigrescens（褐藻）。通过阳极溶出伏安法（ASV）测定每种物种释放分泌物中的配体浓度及其铜结合强度（logK'）。所选藻类在培养 48 小时后释放出浓度范围很广的分泌物（42-117 nM），添加 157 nM 铜可将配体的产量增加 8 倍。未观察到结构复杂性或叶状体厚度与释放配体数量之间存在关系。结合强度（logK'）在物种之间从 7.6 到 8.9 不等，暴露于亚致死铜过剩不会改变这种响应。黑潮 L. nigrescens 对铜过剩表现出快速反应，在几小时内释放出的配体降低了金属的毒性。结果表明，潮间带和浅海大型藻类可能因其作为有机配体生产者的作用而被忽视，因此可能是沿海水域金属络合能力的调节剂。
