• 关键词：纳米氧化锌  锌离子  大型溞  肠道结构  毒性效应

• 基金项目：国家自然科学基金（No.41977340）；山西省重点研发项目科技计划（No.201803D31054）；山西省“1331工程”重点创新团队建设计划资助项目；广东工业大学教学改革项目（No.202023）

• 李美君
• 广东工业大学环境科学与工程学院，广州 510006

• 杜青平
• 广东工业大学环境科学与工程学院，广州 510006

• 罗宏威
• 广东工业大学环境科学与工程学院，广州 510006

• 钟钻佳
• 广东工业大学环境科学与工程学院，广州 510006

• 熊开容
• 广东工业大学环境科学与工程学院，广州 510006

• 许燕滨
• 广东工业大学环境科学与工程学院，广州 510006

• 摘要：研究了不同浓度纳米氧化锌（ZnONP）及其在水中释放的对应浓度的Zn²⁺溶液对大型溞（Daphnia magna）肠道组织显微和亚显微结构的影响，探讨了ZnONP对大型溞的肠道组织毒性效应特征和作用机理.结果表明，0.3 mg·L^-1-Zn²⁺组（Zn²⁺浓度0.170 mg·L^-1）和0.3 mg·L^-1 ZnONP溶液皆对大型溞的肠道造成损伤，主要导致大型溞中肠与直肠之间的连接处发生扭曲，其中ZnONP对肠道组织结构弯曲影响最为明显，0.3 mg·L^-1 ZnONP组引起大型溞个体最大肠道弯曲率高达42%.大型溞肠道组织HE染色结果显示，ZnONP暴露会造成大型溞肠道上皮组织断裂、胞间连接空泡化、纹状缘模糊及杯状细胞脱落等，而相对应浓度Zn²⁺组的毒性较弱.电子显微镜下对大型溞肠道组织亚显微结构观察发现，0.3 mg·L^-1 ZnONP处理组大型溞肠道上皮细胞组织出现微绒毛排列紊乱、脱落、溶解，上皮细胞松散，线粒体双层膜结构不完整，嵴溶解消失，核糖体增多等现象.0.3 mg·L^-1-Zn²⁺组大型溞肠道组织上皮细胞有损伤，但整体结构基本完整.从ZnONP和对应的Zn²⁺所产生的毒性效应特征和各组大型溞机体中Zn元素含量的测定分析，ZnONP对大型溞造成的肠道组织损伤不仅与其释放的Zn²⁺引起的毒性有关，更可能与大型溞对颗粒物摄取的方式或ZnONP在体内的积累量、排泄速率和作用的细胞器等有关.因此，ZnONP对肠道组织毒性效应产生的分子机制还需要 进一步研究.

• Abstract：To understand the toxic effects and mechanisms of zinc oxide nanoparticles （ZnONP） on intestinal tissue of Daphnia magna， the effects of different concentrations of ZnONP and the corresponding concentrations of Zn²⁺ released in water on the intestinal tissue of Daphnia magna at microstructure and sub-microstructure levels were studied. The results showed that both 0.3 mg·L^-1-Zn²⁺ and ZnONP groups damaged the intestinal tract of Daphnia magna， which mainly led to the distortion of the junction between the midgut and rectum of Daphnia magna. ZnONP caused the most obvious effect on the bending of intestinal tissue structure， and the maximum bending rate of intestinal tract caused by 0.3 mg·L^-1 ZnONP group was 42%. The results from intestinal HE staining of Daphnia magna showed that ZnONP exposure could cause rupture of intestinal epithelial tissue， vacuolization of intercellular connections， blurred striatum， and shedding of goblet cells， while corresponding concentration group of Zn²⁺ was less toxic. The submicroscopic structure of intestinal tissue of Daphnia magna was observed by electron microscope. Disordered microvilli of intestinal epithelial cells， loose epithelial cells， broken mitochondrial membrane and ridge and increased ribosomes were observed in Daphnia magna after exposure to 0.3 mg·L^-1 ZnONP. Although the intestinal epithelial tissue of Daphnia magna in 0.3 mg·L^-1-Zn²⁺ group were damaged， the overall structure was intact. Compared the characteristics of toxic effects and Zn content in Daphnia magna of each group produced by ZnONP with the corresponding Zn²⁺ group， the toxic mechanism of intestinal tissue caused by ZnONP was not only related to the toxicity caused by Zn²⁺ released by ZnONP. Furthermore， the damage was more likely related to the uptake of particle matter by Daphnia magna or the accumulation of ZnONP in body， the excretion rate and target organelles acting on. Therefore， the molecular mechanism of ZnONP induced toxic effect on intestinal tissues needs further study.

• Key words：zinc oxide nanoparticle  zinc ion  Daphnia magna  intestine structure  toxic effects

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