Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada M5S 3H6; Environmental NMR Centre and Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, Canada M1C 1A4.
Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada M5S 3H6; Environmental NMR Centre and Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, Canada M1C 1A4.
Ecotoxicol Environ Saf. 2018 Nov 30;164:189-200. doi: 10.1016/j.ecoenv.2018.08.006. Epub 2018 Aug 14.
Previous studies have shown that contaminant toxicity to target organisms is altered by the presence of dissolved organic matter (DOM). Contaminants can bind to DOM and this may alter the bioavailability and subsequent toxicity of the contaminants. However, molecular-level techniques are needed to more closely evaluate the impact of DOM on the sub-lethal biochemical responses to emerging contaminants. To investigate how DOM may alter the metabolic response to organic contaminant exposure, H nuclear magnetic resonance (NMR)-based metabolomics was used to investigate how the metabolome of Daphnia magna changes when Suwannee River DOM (5 mg organic carbon/L) is included in the acute exposure of four contaminants with varying hydrophobicity. Sub-lethal concentrations of the hydrophobic contaminant 17α-ethynylestradiol (EE2), the relatively more polar compounds carbamazepine and imidacloprid, or the anionic contaminant perfluorooctane sulfonate (PFOS) were used. A 48-h exposure to DOM alone had a minor impact on the metabolome of D. magna. There were significant increases in amino acids from EE2 exposure which were reduced in the presence of DOM, suggesting that DOM may alleviate the sub-lethal metabolic response from EE2 exposure through sorption and a reduction in freely dissolved EE2. The metabolome was relatively unaltered with exposure to carbamazepine and imidacloprid in the presence of DOM which is likely because these contaminants are water soluble and did not strongly interact with DOM. PFOS exposure resulted in a more significant metabolic response with DOM suggesting that DOM enhanced the uptake and bioavailability of PFOS in D. magna. As such, the presence of DOM should be considered when determining sensitive molecular-level changes in organisms to sub-lethal organic contaminant exposure.
先前的研究表明，溶解有机质（DOM）的存在会改变目标生物体内污染物的毒性。污染物可以与 DOM 结合，这可能会改变污染物的生物利用度和随后的毒性。然而，需要分子水平的技术来更密切地评估 DOM 对新兴污染物亚致死生化反应的影响。为了研究 DOM 如何改变对有机污染物暴露的代谢反应，使用基于 H 核的核磁共振（NMR）代谢组学来研究当苏万尼河 DOM（5mg 有机碳/L）包含在四种疏水性不同的污染物的急性暴露中时，大型溞的代谢组如何变化。使用了疏水性污染物 17α-乙炔雌二醇（EE2）、相对更极性的化合物卡马西平和吡虫啉、或阴离子污染物全氟辛烷磺酸（PFOS）等亚致死浓度的污染物。单独暴露于 DOM 对大型溞的代谢组仅有轻微影响。EE2 暴露导致的氨基酸含量显著增加，但在 DOM 存在的情况下减少，这表明 DOM 可能通过吸附和减少游离 EE2 来减轻 EE2 暴露的亚致死代谢反应。在 DOM 存在的情况下，暴露于卡马西平和吡虫啉对代谢组的影响相对较小，这可能是因为这些污染物水溶性好，与 DOM 没有强烈相互作用。PFOS 暴露在 DOM 存在下会导致更显著的代谢反应，这表明 DOM 增强了 PFOS 在大型溞中的吸收和生物利用度。因此，在确定对亚致死有机污染物暴露的生物体的敏感分子水平变化时，应考虑 DOM 的存在。
