CIIMAR- Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208 Porto, Portugal.
Area of Toxicology, Faculty of Pharmacy, Universidad de Sevilla, Profesor García González n2, 41012 Seville, Spain.
Toxins (Basel). 2020 Mar 20;12(3):196. doi: 10.3390/toxins12030196.
Toxic cyanobacterial blooms are a major contaminant in inland aquatic ecosystems. Furthermore, toxic blooms are carried downstream by rivers and waterways to estuarine and coastal ecosystems. Concerning marine and estuarine animal species, very little is known about how these species are affected by the exposure to freshwater cyanobacteria and cyanotoxins. So far, most of the knowledge has been gathered from freshwater bivalve molluscs. This work aimed to infer the sensitivity of the marine mussel to single as well as mixed toxic cyanobacterial cultures and the underlying molecular responses mediated by toxic cyanobacteria. For this purpose, a mussel exposure experiment was outlined with two toxic cyanobacteria species, and at 1 × 10 cells/mL, resembling a natural cyanobacteria bloom. The estimated amount of toxins produced by and were respectively 0.023 pg/cell of microcystin-LR (MC-LR) and 7.854 pg/cell of cylindrospermopsin (CYN). After 15 days of exposure to single and mixed cyanobacteria, a depuration phase followed, during which mussels were fed only non-toxic microalga . The results showed that the marine mussel is able to filter toxic cyanobacteria at a rate equal or higher than the non-toxic microalga . Filtration rates observed after 15 days of feeding toxic microalgae were 1773.04 mL/ind.h (for ), 2151.83 mL/ind.h (for ), 1673.29 mL/ind.h (for the mixture of the 2 cyanobacteria) and 2539.25 mL/ind.h (for the non-toxic ). Filtering toxic microalgae in combination resulted in the accumulation of 14.17 ng/g dw MC-LR and 92.08 ng/g dw CYN. Other physiological and biochemical endpoints (dry weight, byssus production, total protein and glycogen) measured in this work did not change significantly in the groups exposed to toxic cyanobacteria with regard to control group, suggesting that mussels were not affected with the toxic microalgae. Nevertheless, proteomics revealed changes in metabolism of mussels related to diet, specially evident in those fed on combined cyanobacteria. Changes in metabolic pathways related with protein folding and stabilization, cytoskeleton structure, and gene transcription/translation were observed after exposure and feeding toxic cyanobacteria. These changes occur in vital metabolic processes and may contribute to protect mussels from toxic effects of the toxins MC-LR and CYN.
有毒蓝藻水华是内陆水生态系统的主要污染物。此外，有毒水华通过河流和水道被携带到河口和沿海水生态系统中。关于海洋和河口动物物种，我们对这些物种接触淡水蓝藻和蓝藻毒素的影响知之甚少。到目前为止，大部分知识都是从淡水双壳贝类中收集到的。这项工作旨在推断海洋贻贝对单一和混合有毒蓝藻培养物的敏感性，以及有毒蓝藻介导的潜在分子反应。为此，设计了一个贻贝暴露实验，使用两种有毒蓝藻物种，和 ，浓度为 1×10 个细胞/mL，类似于自然蓝藻水华。和分别产生 0.023 pg/细胞微囊藻-LR（MC-LR）和 7.854 pg/细胞的节球藻毒素（CYN）的估计毒素量。暴露于单一和混合蓝藻 15 天后，进行了一个净化阶段，在此期间，贻贝只喂食非毒性微藻。结果表明，海洋贻贝能够以等于或高于非毒性微藻的速度过滤有毒蓝藻。在喂食有毒微藻 15 天后观察到的过滤速率分别为 1773.04、2151.83、1673.29 和 2539.25 mL/ind.h（分别为 、 、混合物和非毒性 ）。有毒微藻的混合过滤导致 14.17ng/g dw MC-LR 和 92.08ng/g dw CYN 的积累。与对照组相比，暴露于有毒蓝藻的各组中测量的其他生理和生化终点（干重、足丝生产、总蛋白和糖原）没有显著变化，这表明贻贝没有受到有毒微藻的影响。然而，蛋白质组学揭示了与饮食相关的贻贝代谢的变化，特别是在喂食混合蓝藻的贻贝中更为明显。暴露于有毒蓝藻并喂食后，观察到与蛋白质折叠和稳定、细胞骨架结构以及基因转录/翻译相关的代谢途径发生变化。这些变化发生在重要的代谢过程中，可能有助于保护贻贝免受 MC-LR 和 CYN 毒素的毒性影响。
