Kteeba Shimaa M, El-Adawi Hala I, El-Rayis Osman A, El-Ghobashy Ahmed E, Schuld Jessica L, Svoboda Kurt R, Guo Laodong
School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI 53204, USA; Zoology Department, Faculty of Science, University of Damietta, New Damietta 34511, Damietta, Egypt.
Medical Biotechnology Department, Genetic Engineering and Biotech Institute, Borg El-Arab City for Scientific Research, Universities and Research District Sector, New Borg El-Arab 21934, Alexandria, Egypt.
Environ Pollut. 2017 Nov;230:1125-1140. doi: 10.1016/j.envpol.2017.07.042. Epub 2017 Aug 30.
Exposure experiments were conducted to evaluate the influence of dissolved organic matter (DOM) on the toxicity of ZnO-NPs (10-30 nm) and dissolved Zn at sub-lethal doses (50 and 5 ppm, respectively) to zebrafish (Danio rerio). Humic acid, alginic acid, bovine serum albumin and various natural DOM isolated from rivers as the Milwaukee River-WI (NOMW), Yukon River-AK (NOMA) and Suwannee River-GA DOM (NOMS) were used to represent humic substances (HA), carbohydrates (CHO), proteins (PTN), and natural organic matter (NOM), respectively. Initial experiments were carried out to confirm the toxic effect of ZnO-NPs at 50 ppm, followed by mitigation experiments with different types and concentrations of DOM (0.4-40 mg-C/L). Compared to 0% hatch of 50 ppm ZnO-NPs exposed embryos at 72 h post fertilization (hpf), NOMS, NOMW and HA had the best mitigative effects on hatching (53-65%), followed by NOMA, CHO and PTN (19-35%); demonstrating that the mitigation effects on ZnO-NPs toxicity were related to DOM's quantity and composition. At 96 hpf, 20% of embryos exposed to 50 ppm ZnO-NPs hatched, 100% of embryos reared in embryo medium hatched, and close to 100% of the embryos hatched upon mitigation, except for those mitigated with PTN which had less effect. Dissolved Zn (5 ppm) also exhibited the same toxicity on embryos as ZnO-NPs (50 ppm). However, in the presence of HA, NOM and CHO, the hatching rates at 72 and 96 hpf increased significantly compared to 5% hatch without DOM. The overall mitigation effects produced by DOM followed the order of HA ≥ NOMS > NOM (A&W) > CHO >> PTN, although specific mitigation effects varied with DOM concentration and functionalities. Our results also indicate that the toxicity of ZnO-NPs to embryos was mostly derived from NPs although dissolved Zn released from ZnO-NPs also interacted with embryos, affecting hatching, but to a less extent.
进行了暴露实验，以评估溶解有机物（DOM）对亚致死剂量（分别为50和5 ppm）的氧化锌纳米颗粒（ZnO-NPs，10 - 30纳米）和溶解态锌对斑马鱼（Danio rerio）毒性的影响。使用腐殖酸、海藻酸、牛血清白蛋白以及从河流中分离出的各种天然DOM，如威斯康星州密尔沃基河DOM（NOMW）、阿拉斯加州育空河DOM（NOMA）和佐治亚州苏万尼河DOM（NOMS），分别代表腐殖质（HA）、碳水化合物（CHO）、蛋白质（PTN）和天然有机物（NOM）。首先进行实验确认50 ppm ZnO-NPs的毒性作用，随后进行不同类型和浓度（0.4 - 40 mg-C/L）DOM的缓解实验。与受精后72小时（hpf）暴露于50 ppm ZnO-NPs的胚胎孵化率为0%相比，NOMS、NOMW和HA对孵化的缓解效果最佳（53 - 65%），其次是NOMA、CHO和PTN（19 - 35%）；这表明对ZnO-NPs毒性的缓解效果与DOM 的数量和组成有关。在96 hpf时，暴露于50 ppm ZnO-NPs的胚胎中有20%孵化，在胚胎培养基中饲养的胚胎100%孵化，除了用PTN缓解的胚胎效果较差外，其他缓解后的胚胎孵化率接近100%。溶解态锌（5 ppm）对胚胎的毒性与ZnO-NPs（50 ppm）相同。然而，在HA、NOM和CHO存在的情况下，与没有DOM时5%的孵化率相比，72和96 hpf时的孵化率显著提高。尽管具体的缓解效果因DOM浓度和功能而异，但DOM产生的总体缓解效果顺序为HA≥NOMS > NOM（A&W）> CHO >> PTN。我们的结果还表明，ZnO-NPs对胚胎的毒性主要源于纳米颗粒，尽管从ZnO-NPs释放的溶解态锌也与胚胎相互作用，影响孵化，但程度较小。
