乙草胺对斑马鱼幼鱼早期发育阶段甲状腺相关基因的影响

Effects of acetochlor on the expression of thyroid related genes in early development stage of zebrafish(Danio rerio) larvae

为评价乙草胺的毒性,以斑马鱼为受试生物,采用静态法和实时荧光定量PCR方法,研究了乙草胺对斑马鱼成鱼和胚胎的急性毒性、对胚胎的致畸作用,以及不同窗口期暴露对幼鱼甲状腺相关基因的影响。结果表明:乙草胺对斑马鱼成鱼96 h-LC50值为3.04 mg/L,属中等毒性,对胚胎的120 h-LC50值为5.32 mg/L;斑马鱼胚胎受精后于0.3 mg/L乙草胺中暴露5 d,幼鱼可出现心包囊水肿、脊索弯曲等致畸现象。窗口期暴露试验表明:斑马鱼胚胎受精后3 h起于0.06 mg/L乙草胺中暴露10和14 d,以及在0.3 mg/L乙草胺中暴露10 d,均会引起幼鱼脱碘酶基因(d1、d2)、甲状腺激素受体基因(trα、trβ)、钠/碘同向转运体基因(s1c5a5)、促甲状腺激素释放激素基因(crh)、促甲状腺激素基因(tsh)等的表达呈现不同程度下调,而在0.3 mg/L乙草胺中暴露14 d,除d1的表达量显著上调外,对其余各相关基因的表达均无明显影响。试验结果表明,乙草胺能够干扰斑马鱼幼鱼早期发育,且在不同暴露浓度和时间下,干扰效应存在较大差异。

In order to evaluate the toxicity of acetochlor,zebrafish was used as targeted animal for the test of acute toxicity to adult and embryo,teratogenesis and expression of thyroid related genes in larvae of zebrafish after exposure to acetochlor by static method and quantitive real-time PCR method.The results showed that the 96 h-LC50 value of acetochlor to adult zebrafish and 120 h-LC50 value to larvae was 3. 04 mg / L and 5. 32 mg / L,respectively,suggesting acetochlor has moderate toxicity to zebrafish. Notochord deformation and pericardial edema were observed in larvae after exposure to0. 3 mg / L acetochlor for five days. The result of windowphase exposure test indicated that thyroid related genes such as d1,d2,trα,trβ,s1c5a5,crh,tsh in zebrafish larvae were down-regulated after exposure to 0. 06 mg / L acetochlor from 3 h post-fertilization to 10 d,14 d and exposure to 0. 3 mg / L acetochlor from 3 h post-fertilization to 10 d; however,after exposure to 0. 3 mg / L acetochlor from3 h post-fertilization to 14 d,no significant change in the expression of the above-mentioned genes was observed except that d1 was significant up regulated. The results suggested that acetochlor could disrupt the early development of zebrafish larvae,which depends on the exposure dosage and time.