Universidade Federal do Pampa, Campus Uruguaiana, BR-472 Km 592, ZIP code: 97500-970, RS, Brazil.
Universidade Federal de Santa Maria, Departamento de bioquímica e biologia celular/CCNE/UFSM, Laboratório de Bioquímica Toxicológica, Farmacologia e Organocalcogênios, ZIP code: 97105900, Santa Maria, RS, Brazil.
Mar Environ Res. 2021 Jan;163:105221. doi: 10.1016/j.marenvres.2020.105221. Epub 2020 Dec 1.
Uranium (U) mining is an aquatic environmental concern because most of these harmful compounds are discharged into freshwater, reaching the saline environment as the final destination of this contaminated water. Carbonates are present in ocean waters and are essential for benthic organisms, however they may influence the U-induced toxicity. Thus, the aim of this study was to compare the toxicity of uranium nitrate (UN) and uranium acetate (UA) in Artemia salina (AS), which is one of the leading representatives of the marine biota. The cultures of AS (instar II) maintained in artificial seawater containing CaCO were exposed for 24 h to different concentrations of U compounds. The results showed that AS were more sensitive to UN (LC ≈ 15 μM) when compared with UA (LC ≈ 245 μM) indicating higher toxicity of this U compound. Calculated U speciation indicated that CaUO(CO) and (UO)2CO(OH) complexes predominated under our experimental conditions. The immobilization/lethality was observed after 9 h of exposure for both U compounds. However, only UN caused a significant decrease (≈40%) in the acetylcholinesterase (AChE) activity when compared with control. In order to observe preliminary toxicity effects, we evaluated oxidative stress parameters, such as catalase (CAT) activity, TBARS formation, radical species (RS) generation and cell membrane injury and/or apoptosis (CMI). In this study, we demonstrate that U compounds caused a significant decrease in CAT activity. Similarly, we also observed that UN increased TBARS levels in AS at concentrations 5 times lower than AU (10 μM and 50 μM, respectively). Furthermore, RS generation and CMI were enhanced only on AS treated with UN. Overall, the effects observed here were remarkably significant in AS exposed to UN when compared with AU. In this study, we showed different profiles of toxicity for both U compounds, contributing significantly to the current and scarce understanding of the aquatic ecotoxicity of this heavy metal.
铀（U）开采是一种对水生环境有影响的活动，因为这些有害物质大多数都被排放到淡水中，最终到达这些受污染水的目的地是咸水环境。碳酸盐存在于海水之中，是底栖生物所必需的，但它们可能会影响铀引起的毒性。因此，本研究旨在比较硝酸铀（UN）和乙酸铀（UA）对卤虫（AS）的毒性，AS 是海洋生物群的主要代表之一。在含有 CaCO3 的人工海水中，处于第二龄期的 AS 培养物暴露于不同浓度的 U 化合物中 24 小时。结果表明，与 UA（LC50≈245μM）相比，AS 对 UN（LC50≈15μM）更为敏感，表明这种 U 化合物毒性更高。计算得出的 U 形态表明，在我们的实验条件下，CaUO（CO3）和（UO）2CO（OH）络合物占主导地位。在暴露 9 小时后，两种 U 化合物都观察到了固定/致死现象。然而，只有 UN 会导致乙酰胆碱酯酶（AChE）活性显著下降（≈40%），与对照组相比。为了观察初步的毒性效应，我们评估了氧化应激参数，如过氧化氢酶（CAT）活性、TBARS 形成、自由基（RS）生成以及细胞膜损伤和/或细胞凋亡（CMI）。在这项研究中，我们证明 U 化合物会导致 CAT 活性显著下降。同样，我们还观察到 UN 在 AS 中的浓度比 AU（分别为 10μM 和 50μM）低 5 倍时就会增加 TBARS 水平。此外，仅在 UN 处理的 AS 中观察到 RS 生成和 CMI 增强。总的来说，与 AU 相比，UN 处理的 AS 观察到的效应显著得多。在这项研究中，我们展示了两种 U 化合物的不同毒性特征，这对当前和缺乏对这种重金属的水生生态毒性的理解有重要贡献。
