Balaton Limnological Research Institute, Hungarian Academy of Sciences, Klebelsberg K. u. 3, PO Box 35, H-8237 Tihany, Hungary.
Toxicon. 2011 May;57(6):831-40. doi: 10.1016/j.toxicon.2011.02.007. Epub 2011 Feb 17.
Cylindrospermopsis raciborskii is becoming a major concern among cyanobacteria, due to its potential ability to produce toxic metabolites. We assessed the cytotoxic potential of four C. raciborskii strains (ACT 9502, ACT 9503, ACT 9504 and ACT 9505) isolated from Lake Balaton (Hungary), by lactate dehydrogenase (LDH) leakage measurements and by detecting morphological alterations in CHO-K1 (Chinese Hamster Ovary) cells. The Australian AQS (cylindrospermopsin producer) strain of C. raciborskii and purified cylindrospermopsin (CYN) were used as positive references in both the biochemical and morphological studies. Chemical analysis for known cyanotoxins was performed on aqueous extracts of ACT and AQS strains by the HPLC-MS technique. Comparing threshold values of LDH leakage data, different toxic potentials of cyanobacterial extracts are suggested in short term (3 h) and long (24 h) exposure regimes. In the acute (3 h) experiments the aqueous extract of the ACT 9505 strain proved to be most toxic (EC(50) = 7.4 mg mL(-1)), while after 24 h the ACT 9504 extract was the most effective (EC(50) = 0.65 mg mL(-1)). The extract of the AQS strain and the purified CYN exerted most of their toxic effects after 3 h exposure (EC(50) = 0.74 mg mL(-1), and 0.9 μg mL(-1) respectively). The morphological changes of CHO-K1 cells induced by the crude extracts of the ACT strains included fragmentation of the actin filaments then relocation of the depolymerized actin to the perinuclear region, resulting cell rounding and loss of adhesion. Exposure of CHO-K1 cells to the crude extract of the AQS strain, moreover, resulted cell shrinking and formation of filopodia, i.e. distinctly different cytological alterations from that induced by the ACT extracts and the purified CYN. Chemical analysis of the cyanobacterial crude extracts confirmed the presence of cylindrospermopsin in the extract of the AQS strain (8.5 mg CYN g(-1) dry weight), and none of the presently known cyanotoxins have been analytically confirmed in the extracts of the ACT strains isolated from the Lake Balaton. Although a significant toxicity of all four ACT C. raciborskii strains is confirmed by both biochemical and morphological studies, our results also pointed out the necessity of further studies to identify the toxic, but still unknown metabolic components produced by these cyanobacterial members of the phytoplankton communities.
微囊藻毒素生产商澳大利亚 AQS 株（产微囊藻毒素）和纯化的微囊藻毒素（CYN）被用作生物化学和形态学研究的阳性对照。采用 HPLC-MS 技术对 ACT 和 AQS 株的水提物进行了已知的蓝藻毒素的化学分析。通过比较 LDH 漏出数据的阈值，表明在短期（3 小时）和长期（24 小时）暴露条件下，不同的蓝藻提取物具有不同的毒性潜力。在急性（3 小时）实验中，ACT 9505 株的水提物被证明是最有毒的（EC50=7.4mg/mL），而在 24 小时后，ACT 9504 提取物是最有效的（EC50=0.65mg/mL）。AQS 株的提取物和纯化的 CYN 在暴露 3 小时后表现出最大的毒性作用（EC50 分别为 0.74mg/mL 和 0.9μg/mL）。ACT 株粗提取物诱导 CHO-K1 细胞的形态变化包括肌动蛋白丝的片段化，然后解聚的肌动蛋白重新定位到核周区域，导致细胞圆化和失去粘附。暴露于 AQS 株粗提取物的 CHO-K1 细胞导致细胞收缩和形成丝状伪足，即与 ACT 提取物和纯化的 CYN 诱导的细胞形态变化明显不同。蓝藻粗提取物的化学分析证实了 AQS 株提取物中存在微囊藻毒素（8.5mg CYN g(-1)干重），而在从巴拉顿湖分离的 ACT 株的提取物中，尚未分析证实存在任何目前已知的蓝藻毒素。尽管生化和形态学研究都证实了所有四种 ACT 微囊藻的显著毒性，但我们的结果还指出，需要进一步研究以确定这些浮游植物群落中的蓝藻成员产生的有毒但仍未知的代谢成分。
