全氟辛烷基磺酸与纳米氧化锌对斑马鱼联合毒性效应研究

发布时间：2018-08-09 20:33

【摘要】：污染物复合暴露对生物体的毒性危害是目前人们关注的焦点问题。全氟辛烷基磺酸(Perfluorooctane sulfonate,PFOS,C8F17SO3)是一类持久性有机污染物,对生物具有肝脏、神经、生殖和发育等毒性。由于PFOS在日常加工产品中的广泛应用,以及在土壤,水体和生物体中的广泛检出,对人们的健康造成了严重的危害,其毒性也是近年来人们研究的热点。纳米氧化锌(Nano-ZnO)是一种典型的纳米金属氧化物,其独特的化学特性使其使用量日益增加。NanoZnO可以通过皮肤进入生物体,并在体内富集,其对生物的毒害作用也引起了人们的重视。由于环境中PFOS和Nano-ZnO的排放量日益增多,它们在水中的潜在共存性增大,探究其对水生生物的复合暴露毒性及其作用机制变得十分必要。本文研究了PFOS和Nano-ZnO复合暴露对斑马鱼的发育毒性、甲状腺毒性和生殖毒性的影响及其致毒机制。为污染物复合暴露对鱼类毒性影响的应急处理提供了基础研究,同时为污染物水生态风险分析提供科学依据。根据急毒实验结果得出,96 h PFOS和Nano-ZnO的LC50值分别为3.502 mg/L和60 mg/L。同时,设计PFOS与Nano-ZnO等效应复合暴露以及(P 0.4+Z 50),(P 0.8+Z 50)和(P 1.6+Z 50)复合暴露组进行96 h胚胎发育毒性实验。另外将胚胎暴露于(P 0.2+Z 50),(P 0.4+Z 50)和(P 0.8+Z 50)复合暴露组和等效应复合暴露组中14 d后,考察Nano-ZnO的加入对PFOS诱导甲状腺毒性的影响,分析联合毒性类型和可能的致毒机制。最后利用(P 0.05+Z 1.7),(P 0.1+Z 3.4)和(P 0.2+Z6.75)处理组来考察等效应暴露对斑马鱼亲本代生殖毒性和子代胚胎质量的影响。本文探讨了污染物对斑马鱼从孵化到性成熟内各个发育时期相应毒性指标影响,研究成果如下:(1)PFOS和Nano-ZnO单独暴露均可以引起胚胎的急性毒性,PFOS和Nano-ZnO复合暴露后导致胚胎急性毒性增强。Nano-ZnO的加入显著增强了PFOS对幼鱼死亡率和畸形率诱导,抑制胚胎的孵化率和心率。复合暴露同时诱导幼鱼体内氧化应激和细胞凋亡反应增强。Nano-ZnO的出现激活了PFOS对氧化应激酶(SOD、GPx与MDA)和细胞凋亡酶(Caspase-3与Caspase-9)活性诱导,上调了细胞凋亡相关基因(p53,Bax,Bcl-2,caspase-3与caspase-9)的表达,同时抑制了氧化应激相关基因(SOD1、Cat与GPx1a)的表达。复合暴露后毒性增强的原因可能是由于PFOS的独特的化学性质,改变了细胞膜的通透性,使小粒径大分子污染物(Nano-ZnO)更容易进入膜内,进而影响体内一些重要的酶活性和激素分泌平衡,导致Nano-ZnO细胞内残留量增加,最终诱导胚胎的发育毒性增强。(2)Nano-ZnO与PFOS两种复合暴露类型均增强了幼鱼14 d的发育毒性,(P 0.8+Z 25)和(P 0.8+Z 50)mg/L复合暴露组显著提高幼鱼的死亡率和畸形率,同时抑制了幼鱼的体长。Nano-ZnO的加入使得PFOS对幼鱼体内T3含量诱导显著增强,同时抑制了T4含量。Nano-ZnO的加入显著的抑制了TSHβ与TRα基因的表达,上调了TRβ、Deio1、Deio2、NIS与CRH基因的表达,同时抑制TG、TTR基因和蛋白的表达,但对TPO基因表水平没有影响。研究结果表明,PFOS与Nano-ZnO相互作用进入细胞膜内,干扰幼鱼甲状腺轴的功能,影响碘的吸收,合成、运输和甲状腺激素核受体的绑定,破坏HPT轴作用位点,破坏体内甲状腺激素平衡从而对幼鱼的生长发育造成一系列的危害,这可能是PFOS与Nano-ZnO复合暴露增强幼鱼甲状腺毒性的原因。(3)复合暴露能够提高亲本代斑马鱼累积死亡数量,抑制成鱼体重与体长的发育,降低产卵量与胚胎中卵蛋白的含量。但并不影响成鱼性腺指数值,说明复合暴露不影响斑马鱼卵巢与精巢的重量。复合暴露影响精巢和卵巢内成熟细胞的生成,诱导肝脏和肠器官的细胞空穴及间隙增大。复合暴露组中的成鱼外周血细胞中彗星尾距值和微核率随着暴露浓度的升高,也显现增加状态,说明Nano-ZnO能增强PFOS对斑马鱼血细胞DNA的损伤程度。(P 0.1+Z 3.4)和(P0.2+Z 6.75)复合处理组能够显著降低雄鱼体内T的含量,不影响雌鱼体内T的含量。而对雌鱼体内E2的含量抑制作用明显,但对雄鱼体内E2含量没有影响,说明复合暴露影响斑马鱼体内性激素的分泌。Nano-ZnO单独暴露对Vtg1基因的表达没有显著影响,但与PFOS复合暴露后能显著地抑制斑马鱼肝脏组织内Vtg1基因的表达,进而影响子代胚胎中卵黄蛋白含量。复合暴露同时提高子代幼鱼死亡率,降低卵受精率和孵化率,对子代幼鱼体长和畸形率没有显著影响。复合暴露后生殖毒性增强的可能原因是由于污染物通过影响有机体内性激素的分泌来影响动物体的性器官成熟、副性征发育及维持性功能等作用。综上所述,环境中Nano-ZnO的存在会干扰PFOS对斑马鱼的发育毒性,甲状腺毒性和生殖毒性,且联合毒性作用增强。因此,进行污染物的风险评价,不能仅仅从单一污染物的毒性出发,还要考虑复合污染物的相互作用趋势,从而做出合理的风险评估,保护公众的生命健康。
[Abstract]:The toxicity of pollutants to organisms is the focus of attention at present. Perfluorooctane sulfonate (PFOS, C8F17SO3) is a class of persistent organic pollutants, which have liver, nerve, reproductive and developmental toxicity to organisms. Because PFOS is widely used in daily processing products, and in soil The extensive detection of soil, water and organism has caused serious harm to people's health, and its toxicity is also a hot spot in recent years. The nano Zinc Oxide (Nano-ZnO) is a typical nano metal oxide. Its unique chemical properties make it use more and more.NanoZnO to enter the organism through skin and in body. The toxicity of PFOS and Nano-ZnO in the environment is increasing, and the potential coexistence of them in the water is increasing. It is very necessary to explore the compound exposure toxicity of the aquatic organisms and its mechanism of action. This paper studies the combined exposure of PFOS and Nano-ZnO to zebrafish. The effects of developmental toxicity, thyroid toxicity and reproductive toxicity and its toxic mechanism provide a basic study for the emergency treatment of the effects of compound exposure to fish on the toxicity of fish, and provide a scientific basis for the analysis of the ecological risk of pollutant water. According to the results of the acute toxicity test, the LC50 values of 96 h PFOS and Nano-ZnO are 3.502 mg/L and 60 mg, respectively. /L. also designed PFOS and Nano-ZnO effect compound exposure and (P 0.4+Z 50), (P 0.8+Z 50) and (P 1.6+Z 50) composite exposure group for 96 h embryo development toxicity test. The effects of thyroid toxicity, combined toxicity types and possible toxic mechanisms were analyzed. Finally, the effects of equal effect exposure on the reproductive toxicity and offspring embryo quality of zebrafish were investigated using (P 0.05+Z 1.7) (P 0.1+Z 3.4) and (P 0.2+Z6.75) treatment group. The results were as follows: (1) the exposure of PFOS and Nano-ZnO could cause acute toxicity of embryo. After PFOS and Nano-ZnO combined exposure, the acute toxicity of the embryo was enhanced by the addition of.Nano-ZnO, which significantly enhanced the mortality and deformity rate induced by PFOS, and inhibited the hatchability and heart rate of the embryo. Exposure to oxidative stress and cell apoptosis induced by exposure to.Nano-ZnO increased the activation of PFOS to the activity of oxidative stress kinase (SOD, GPx and MDA) and apoptosis enzyme (Caspase-3 and Caspase-9), up regulation of apoptosis related genes (p53, Bax, Bcl-2, caspase-3 and caspase-9), and inhibition of oxidative stress. The expression of gene (SOD1, Cat and GPx1a). The cause of toxicity enhancement after the compound exposure may be due to the unique chemical properties of PFOS, which changes the permeability of the cell membrane, which makes the small size large molecular pollutants (Nano-ZnO) more easily entered into the membrane, and then affects some important enzyme activities and hormone secretion in the body, resulting in the internal residue of Nano-ZnO cells. (2) the developmental toxicity of two species of Nano-ZnO and PFOS increased the developmental toxicity of 14 d in young fish, and (P 0.8+Z 25) and (P 0.8+Z 50) mg/L compound exposure group significantly increased the mortality and malformation rate of young fish, and inhibited the addition of.Nano-ZnO in young fish to PFOS for T3. The content of.Nano-ZnO was significantly enhanced and the expression of TSH beta and TR alpha gene was inhibited significantly by the addition of T4 content, and the expression of TR beta, Deio1, Deio2, NIS and CRH genes was up-regulated, and the expression of TG, TTR gene and protein were inhibited, but the TPO gene surface level was not affected. In the membrane, it interferes with the function of the juvenile thyroid axis, affecting the absorption, synthesis, transportation and binding of the thyroid hormone nuclear receptor, destroying the HPT axis action site, destroying the thyroid hormone balance in the body and causing a series of harm to the growth and development of the young fish, which may be the primary toxicity of PFOS and Nano-ZnO to the hypothyroidism of young fish. (3) complex exposure can increase the number of cumulative deaths in the parent zebrafish, inhibit the growth of body weight and body length, reduce the amount of egg production and egg protein in the embryo, but do not affect the value of the adult gonadal finger, indicating that the compound exposure does not affect the weight of the ovaries and the sperms of the zebrafish. In the compound exposure group, the comet tail distance and micronucleus rate also increase with the increase of exposure concentration, indicating that Nano-ZnO can enhance the damage degree of PFOS to the DNA of zebrafish blood cells. (P 0.1+Z 3.4) and (P0.2+Z 6.75) compound treatment group It can significantly reduce the content of T in the male body and not affect the content of T in the female fish, but the inhibitory effect on the content of E2 in the female fish is obvious, but it has no effect on the E2 content in the male fish, which indicates that the compound exposure affects the secretion of sex hormone in the zebrafish body, and the.Nano-ZnO alone exposure has no significant influence on the expression of the Vtg1 base, but with the PFOS compound storm. After exposure, the expression of Vtg1 gene in the liver tissue of zebrafish was inhibited significantly, and the yolk protein content in the offspring embryos was affected. The compound exposure increased the mortality of the juvenile fish, reduced the fertilization rate and hatchability of the eggs, and had no significant influence on the length and the malformation rate of the offspring. The possible reasons for the enhancement of reproductive toxicity after the compound exposure were the possible reasons for the increase of reproductive toxicity. The presence of Nano-ZnO in the environment may interfere with the developmental toxicity of PFOS to zebrafish, thyroid toxicity and reproductive toxicity, and combined toxicity, and thus contaminate the body. Risk assessment can not only start from the toxicity of a single pollutant, but also consider the interaction trend of compound pollutants, so as to make a reasonable risk assessment and protect the health of the public.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X171.5

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