Interdisciplinary Centre of Marine and Environmental Research, CIIMAR/CIMAR, Porto, Portugal.
Ecotoxicol Environ Saf. 2013 Aug;94:45-53. doi: 10.1016/j.ecoenv.2013.04.019. Epub 2013 May 30.
Toxic cyanobacteria and cyanotoxins have been pointed as important players in the control of phytoplankton diversity and species abundance, causing ecological unbalances and contamination of the environment. In vitro experiments have been undertaken to address the impact of toxic cyanobacteria in green algae. In this regard the aim of this work was to compare the toxicity of two cyanobacteria species, Aphanizomenon ovalisporum and Microcystis aeruginosa, to the green alga Chlorella vulgaris by assessing culture growth when exposed for three and seven days to (I) cyanobacterial cell extracts and (II) pure toxins microcystin-LR (MC-LR) and cylindrospermopsin (CYN). The biochemical response of the green alga to pure toxins was also characterized, through the activity of the antioxidant markers glutathione S-transferase (GST) and glutathione peroxidase (GPx) and the expressed extracellular proteins in seven-day exposed cultures. A. ovalisporum crude extracts were toxic to C. vulgaris. Pure toxins up to 179.0 µg/L, on the other hand, stimulated the green alga growth. Growth results suggest that the toxicity of A. ovalisporum extracts is likely due to a synergistic action of CYN and other metabolites produced by the cyanobacterium. Regarding the green alga antioxidant defense mechanism, CYN at 18.4 and 179.0 µg/L increased the activity of GPx and GST while MC-LR inhibited the enzymes' activity at a concentration of 179.0 µg/L demonstrating a contrasting mode of action. Moreover the identification of F-ATPase subunit, adenylate cyclase, sulfate ABC transporter, putative porin, aspartate aminotransferase, methylene-tetrahydrofolate dehydrogenase and chlorophyll a binding proteins in the culture medium of C. vulgaris indicates that biochemical processes involved in the transport of metabolites, photosynthesis and amino acid metabolism are affected by cyanobacterial toxins and may contribute to the regulation of green alga growth.
有毒蓝藻和蓝藻毒素已被指出是控制浮游植物多样性和物种丰度的重要因素，导致生态失衡和环境污染。已经进行了体外实验来研究有毒蓝藻对绿藻的影响。在这方面，这项工作的目的是比较两种蓝藻物种，微囊藻和鱼腥藻，对绿藻小球藻的毒性，通过评估暴露于（I）蓝藻细胞提取物和（II）纯毒素微囊藻毒素-LR（MC-LR）和柱孢藻毒素（CYN）的藻类生长来比较毒性。通过测定抗氧化标记物谷胱甘肽 S-转移酶（GST）和谷胱甘肽过氧化物酶（GPx）的活性以及在暴露于纯毒素的 7 天培养物中表达的细胞外蛋白，还对绿藻的生化反应进行了表征。鱼腥藻粗提取物对小球藻有毒。另一方面，纯毒素高达 179.0 µg/L 刺激绿藻生长。生长结果表明，鱼腥藻提取物的毒性可能是由于 CYN 和蓝藻产生的其他代谢物的协同作用。关于绿藻抗氧化防御机制，CYN 在 18.4 和 179.0 µg/L 时增加了 GPx 和 GST 的活性，而 MC-LR 在 179.0 µg/L 时抑制了酶的活性，表明其作用方式相反。此外，在小球藻培养液中鉴定到 F-ATP 酶亚基、腺苷酸环化酶、硫酸盐 ABC 转运蛋白、假定的孔蛋白、天冬氨酸转氨酶、亚甲基四氢叶酸脱氢酶和叶绿素 a 结合蛋白，表明参与代谢物运输、光合作用和氨基酸代谢的生化过程受到蓝藻毒素的影响，可能有助于调节绿藻的生长。
