Faculty of Sciences, Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Uni Carl Vogt, 66 Blvd Carl-Vogt, Geneva CH 1211, Switzerland.
Bren School of Environmental Science & Management, University of California, Santa Barbara, Santa Barbara, California 93106-5131, United States.
Environ Sci Technol. 2021 Mar 16;55(6):3876-3887. doi: 10.1021/acs.est.0c08416. Epub 2021 Feb 25.
Metabolomics characterizes low-molecular-weight molecules involved in different biochemical reactions and provides an integrated assessment of the physiological state of an organism. By using liquid chromatography-mass spectrometry targeted metabolomics, we examined the response of green alga to sublethal concentrations of inorganic mercury (IHg) and monomethylmercury (MeHg). We quantified the changes in the levels of 93 metabolites preselected based on the disturbed metabolic pathways obtained in a previous transcriptomics study. Metabolites are downstream products of the gene transcription; hence, metabolite quantification provided information about the biochemical status of the algal cells exposed to Hg compounds. The results showed that the alga adjusts its metabolism during 2 h exposure to 5 × 10 and 5 × 10 mol L IHg and MeHg by increasing the level of various metabolites involved in amino acid and nucleotide metabolism, photorespiration, and tricarboxylic acid (TCA) cycle, as well as the metabolism of fatty acids, carbohydrates, and antioxidants. Most of the metabolic perturbations in the alga were common for IHg and MeHg treatments. However, the exposure to IHg resulted in more pronounced perturbations in the fatty acid and TCA metabolism as compared with the exposure to MeHg. The observed metabolic perturbations were generally consistent with our previously published transcriptomics results for exposed to the comparable level of IHg and MeHg. The results highlight the potential of metabolomics for toxicity evaluation, especially to detect effects at an early stage of exposure prior to their physiological appearance.
代谢组学鉴定了参与不同生化反应的低分子量分子，提供了生物体生理状态的综合评估。我们采用液质联用靶向代谢组学方法，研究了绿藻对亚致死浓度无机汞（IHg）和甲基汞（MeHg）的响应。我们定量检测了 93 种代谢物水平的变化，这些代谢物是根据先前转录组学研究中获得的代谢途径紊乱情况预选的。代谢物是基因转录的下游产物；因此，代谢物的定量分析提供了有关暴露于 Hg 化合物的藻类细胞生化状态的信息。结果表明，藻类通过增加参与氨基酸和核苷酸代谢、光呼吸和三羧酸（TCA）循环以及脂肪酸、碳水化合物和抗氧化剂代谢的各种代谢物的水平，在 5×10 和 5×10 mol L IHg 和 MeHg 暴露的 2 小时内调整其代谢。藻类的大多数代谢紊乱对于 IHg 和 MeHg 处理都是共同的。然而，与暴露于 MeHg 相比，暴露于 IHg 导致脂肪酸和 TCA 代谢更明显的紊乱。观察到的代谢紊乱与我们之前发表的暴露于可比水平的 IHg 和 MeHg 的藻类转录组学结果基本一致。结果强调了代谢组学在毒性评估中的潜力，特别是在暴露的早期阶段检测毒性，此时生理变化尚未出现。
