纳米二氧化钛致日本青鳉鱼胚胎毒性效应特征

Toxic effects of nanometer titanium dioxide on embryos of Japanese medaka(Oryzias latipes)

采用青鳉鱼胚胎暴露的方法,研究不同浓度纳米TiO_2对胚胎的毒性效应.结果表明,纳米TiO_224 h的半数致死率LD50为115.17 mg·L^(-1),但不同浓度组引起致死效应差别很大,不存在剂量—效应关系.随着处理浓度从高到低的变化,青鳉鱼胚胎孵化率呈现V字型降低.孵化率最低的为0.1 mg·L^(-1)纳米TiO_2处理组,其孵化率低于10%.高浓度组纳米TiO_2(1 mg·L^(-1)试验组和10 mg·L^(-1)试验组)导致青鳉鱼胚胎孵化时间延迟1—2周.高浓度组(1 mg·L^(-1)和10 mg·L^(-1)处理组)和低浓度组(0.1 mg·L^(-1)和0.01 mg·L^(-1)处理组)的纳米TiO_2对青鳉鱼胚胎和幼鱼造成的畸形毒性特征不同.高浓度组主要造成卵黄囊水肿,低浓度组的毒性特征主要是卵膜破损和胚胎急性致死.对纳米TiO_2的致毒机理,尤其是低于0.1mg·L^(-1)的毒性效应和致毒机理需要进一步研究.

In this study,we investigated the toxic effects of nano-TiO_2 on embryos of the Medaka fish（Oryzias latipes） at different exposure concentrations of nano-TiO_2.The results showed that the LD50（Lethal Dose,50%） of nano-TiO_2 at 24 h was 115.17 mg·L^（-1）.However,the lethal effects of Medaka embryos varied greatly among different concentration groups,and no dose-effect correlation can be observed.The hatching rate of Medaka embryos was no more than 10% and changed as ″V″pattern with the increasing TiO_2 concentrations.The lowest hatching point was found in the treatment group of 0.1 mg·L^（-1） nano-TiO_2.The hatching time of Medaka embryos was delayed for 1—2 weeks in the groups treated by higher exposure concentrations（1 mg·L^（-1） or 10 mg·L^（-1））.Malformations of Medaka embryos were observed in all treatment groups.The abnormal characteristic of Medaka embryos and juvenile fish was different between low concentration groups（0.1 mg·L^（-1） and0.01 mg·L^（-1）） and high concentration groups（1 mg·L^（-1） and 10 mg·L^（-1））.The treatment groups with high concentrations of nano-TiO_2 caused edema of yolk sac of Medaka embryos,while those with low concentrations led to membrane rupture of eggs,part of which was broken and suffered acutelethality.Therefore,the variation of toxicities of nano-TiO_2 towards Medaka embryos can be attributed to different exposure concentrations of nanomaterials.Further studies with lower exposure concentrations（ 0.1 mg·L^（-1）） are needed to better understand the toxic mechanism of nano-TiO_2 to aquatic organisms.