Barón-Sola Ángel, Toledo-Basantes Margarita, Arana-Gandía María, Martínez Flor, Ortega-Villasante Cristina, Dučić Tanja, Yousef Ibraheem, Hernández Luis E
Laboratory of Plant Physiology-Department of Biology/Research Centre for Biodiversity and Global Change, Universidad Autónoma Madrid, Darwin 2, ES28049 Madrid, Spain.
CELLS ALBA, Carrer de la Llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
J Hazard Mater. 2021 Oct 5;419:126502. doi: 10.1016/j.jhazmat.2021.126502. Epub 2021 Jun 26.
Toxic metals such as cadmium (Cd) and mercury (Hg) represent a threat to photosynthetic organisms of polluted aquatic ecosystems, and knowledge about mechanisms of toxicity is essential for appropriate assessment of environmental risks. We used Synchrotron Radiation-Fourier Transformed Infrared microspectroscopy (μSR-FTIR) to characterise major changes of biomolecules caused by Cd and Hg in the model green microalga Chlamydomonas reinhardtii. μSR-FTIR showed several metabolic alterations in different biochemical groups such as carbohydrates, proteins, and lipids in a time-dose dependent manner, with the strongest changes occurring at concentrations above 10 μM Cd and 15 μM Hg after short-term (24 h) treatments. This occurred in a context where metals triggered intracellular oxidative stress and chloroplast damage, along with autophagy induction by overexpressing AUTOPHAGY-RELATED PROTEIN 8 (ATG8). Thin layer chromatography analysis confirmed that toxic metals promoted remarkable changes in lipid profile, with higher degree of esterified fatty acid unsaturation as detected by gas chromatography coupled with mass spectrometry. Under Cd stress, there was specifically higher unsaturation of free fatty acids, while Hg led to stronger unsaturation in monogalactosyldiacylglycerol. μSR-FTIR spectroscopy proved as a valuable tool to identify biochemical alterations in microalgae, information that could be exploited to optimise approaches for metal decontamination.
镉（Cd）和汞（Hg）等有毒金属对受污染水生生态系统中的光合生物构成威胁，了解其毒性机制对于准确评估环境风险至关重要。我们利用同步辐射傅里叶变换红外显微光谱（μSR-FTIR）来表征模式绿藻莱茵衣藻中镉和汞引起的生物分子的主要变化。μSR-FTIR显示不同生化组（如碳水化合物、蛋白质和脂质）中存在多种代谢改变，且呈时间-剂量依赖性，短期（24小时）处理后，在镉浓度高于10μM和汞浓度高于15μM时变化最为强烈。这种情况发生在金属引发细胞内氧化应激和叶绿体损伤，以及通过过度表达自噬相关蛋白8（ATG8）诱导自噬的背景下。薄层色谱分析证实，有毒金属促使脂质谱发生显著变化，气相色谱-质谱联用检测到酯化脂肪酸不饱和度更高。在镉胁迫下，游离脂肪酸的不饱和度尤其高，而汞则导致单半乳糖基二酰基甘油的不饱和度更高。μSR-FTIR光谱被证明是识别微藻生化改变的有价值工具，这些信息可用于优化金属去污方法。
