Karadjova Irina B, Slaveykova Vera I, Tsalev Dimiter L
Environmental Biophysical Chemistry, ISTE-ENAC, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 2, CH-1015 Lausanne, Switzerland.
Aquat Toxicol. 2008 May 30;87(4):264-71. doi: 10.1016/j.aquatox.2008.02.006. Epub 2008 Mar 10.
The present study focuses on the biouptake, biotransformations, and toxicity of arsenic species on the marine green alga Chlorella salina in seawater from the Bulgarian Black Sea coast. Exposure to equal concentrations of As(III) or As(V) led to equivalent levels of toxicity and total intracellular arsenic content. Biouptake and toxicity of methylated arsenic species, monomethylarsonate (MMA) and dimethylarsinate (DMA), were approximately three orders of magnitude lower than those for inorganic arsenic species. Seawater enrichment with phosphate (up to 1.3 mg P L(-1)) resulted in a significant reduction of both intracellular As content and toxicity due to As(III) and As(V). In contrast, the toxicity and intracellular content of MMA and DMA were unaffected by the presence of phosphate. We measured the distribution and excretion of intracellular arsenic species, and demonstrated that the release of As(V) and/or As(III), together with the bio-reduction of As(V) and the subsequent methylation of As(III) may be a detoxification mechanism for these algae. The implications of the results with respect to arsenic species bioavailability and toxicity in marine water are further discussed.
本研究聚焦于保加利亚黑海沿岸海水中砷形态对海洋绿藻盐生小球藻的生物摄取、生物转化及毒性。暴露于同等浓度的As(III)或As(V)会导致同等水平的毒性和细胞内总砷含量。甲基化砷形态一甲基胂酸（MMA）和二甲基胂酸（DMA）的生物摄取和毒性比无机砷形态低约三个数量级。海水中添加磷酸盐（浓度高达1.3 mg P L(-1)）会导致细胞内砷含量以及As(III)和As(V)所致毒性显著降低。相反，MMA和DMA的毒性及细胞内含量不受磷酸盐存在的影响。我们测定了细胞内砷形态的分布和排泄情况，并证明As(V)和/或As(III)的释放，以及As(V)的生物还原和随后As(III)的甲基化可能是这些藻类的一种解毒机制。文中进一步讨论了这些结果对海水中砷形态生物可利用性和毒性的影响。
