手性农药氟环唑对映体对斜生栅藻的毒性效应差异以及选择性生物富集研究

发布时间：2018-01-29 04:03

本文关键词： 氟环唑斜生栅藻对映选择性毒性富集　出处：《贵州大学》2015年硕士论文　论文类型：学位论文

【摘要】：氟环唑是美国巴斯夫公司于1985年开发的一种高效、低毒的三唑类手性杀菌剂,在农业上被广泛使用。然而,长期使用氟环唑会使其进入淡水循环造成水体污染。本实验考察了氟环唑及其对映体对斜生栅藻的生长抑制,通过计算半最大效应浓度(EC50)比较了氟环唑对映体的急性毒性大小;检测了氟环唑对映体对斜生栅藻细胞内光合色素和脂质过氧化物丙二醛(MDA)含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性的影响;利用透射电子显微镜(TEM)观察了氟环唑对映体处理过的斜生栅藻细胞的超微结构的变化,并探讨氟环唑对映体的选择性毒性效应;研究了氟环唑对映体在栅藻细胞中的选择性富集和降解。结果表明:氟环唑外消旋体、(-)-对映体和(+)-对映体的96h-EC50分别为5.850,4.296和2.488 mg/L。当给药量较低(1 mg/L)时,rac-及(-)-氟环唑处理的藻细胞中总叶绿素含量分别高于对照组14.2%和1.3%,随着给药量增加,藻细胞中叶绿素和类胡萝卜素含量均降低。氟环唑及其对映体对斜生栅藻细胞的脂质过氧化物(MDA)含量以及抗氧化物酶(SOD和CAT)活性的影响也表现出对映选择性。另外,氟环唑对映体还会导致藻细胞产生超微结构的改变,包括质壁分离现象,叶绿体和细胞核的消失,脂肪低和淀粉颗粒的累积等。斜生栅藻可富集氟环唑,并有助于氟环唑在水中的消解。持续暴露于rac-氟环唑中的栅藻,(-)-和(+)-对映体的富集量第三天达到最大值,分别为28.4和21.6 mg/kg。之后两对映体的富集量下降,并出现对映选择性翻转。暴露于氟环唑单体的栅藻,富集结果在整个实验期内未发现对映体互变,并且(-)-氟环唑和(+)-氟环唑单体的总富集量分别是外消旋体暴露时的1.53和1.75倍,表明氟环唑对映体以单体形式存在时比外消旋体形式更容易被藻细胞富集。
[Abstract]:Fluoxazole is a highly efficient and low toxic triazole chiral bactericide developed by Pasteur Company in 1985, which is widely used in agriculture. Long term use of fluoxazole will cause water pollution by entering fresh water cycle. The growth inhibition of flucyclazole and its enantiomers on S. obliquus was investigated in this experiment. The acute toxicity of flucyclazole enantiomers was compared by calculating the semi-maximum effect concentration (EC50). The effects of flucyclazole enantiomers on the contents of photosynthetic pigment, malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) in the cells of S. obliquus were determined. Transmission electron microscopy (TEM) was used to observe the ultrastructural changes of the cells treated with flucyclazole enantiomers, and to investigate the selective toxicity of flucyclazole enantiomers. The selective enrichment and degradation of flucyclazole enantiomers in algae cells were studied. The 96 h-EC50 of the enantiomers were 5.850 mg / L and 2.488 mg / L, respectively, when the dosage was lower than 1 mg / L. The content of total chlorophyll in algal cells treated with rac- and trifluocyclozole was 14.2% and 1.3 respectively higher than that in control group. The contents of lipid peroxides (MDAs) and antioxidant enzymes (SOD and CAT) in flucyclazole and its enantiomers were decreased. The effect of activity also showed enantioselectivity. Flucyclazole enantiomers also lead to ultrastructural changes in algal cells, including the separation of cytoplasm, the disappearance of chloroplasts and nuclei, low fat levels and the accumulation of starch granules, etc. It also contributes to the digestion of flucyclazole in water. The concentration of the enantiomers in rac-fluoxazole is the highest on the third day. The concentration of the enantiomers decreased and the enantioselectivity flipped after 28.4 and 21.6 mg / kg, respectively. No enantiomeric interaction was found in the whole experiment period, and the total enrichment amounts were 1.53 and 1.75 times higher than those of the racem-exposed monomers, respectively. The results showed that flucyclazole enantiomers were more easily enriched by algal cells in the form of monomers than racemes.
【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X592;TQ450.26

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