Reproduction Endocrin Disruption By Triclocarban And Its Induces Apoptosis In Zebrafish (Danio Rerio)

Triclocarban(TCC)is widely used as antibacterial agent in products such as toothpaste and fabrics.Due to TCC can't be completely remove from domestic wastewater and the degradation efficiency is low,it is widely existed in the water environment.TCC has been regarded as a new type of environmental endocrine disruptor.Therefore,more and more attention has been paid to the effects of TCC on organisms.Studies have shown that TCC has oxidative damage and endocrine disruption effects on organisms,while TCC 's research on fish is limited to the detection of embryonic antioxidant enzymes Little is known about its potential molecular mechanisms,and its toxic effects on different life stages and offspring are unclear.Therefore,this study takes zebrafish as the research object,explores the potential toxicity and mechanism of TCC to larvae and offspring,and provides scientific basis for the potential risk assessment of TCC to non-target organisms.In this study,a 96-hour acute exposure test was first performed on zebrafish embryos,larvae,juveniles and adults to determine the life stage when zebrafish is most sensitive to TCC.Next,the effects of short-term TCC exposure on larvae were explored.3 days post fertilization(3 dpf)of larvae were exposed to different concentrations(0,1.25,2.5,5,10 ?g / L)Toxicity of TCC to water in terms of sex hormone levels,oxidative stress,apoptosis,and endocrine was discussed at 24 h,48 h,and 72 h in triclocarban water.Finally,the adult zebrafish(F0)was exposed to TCC,and the F1 embryos of the exposed and unexposed parents were collected after the exposure,and F0 and F1 were evaluated in terms of development parameters,antioxidant status,and expression levels of reproductive endocrine-related genes.Toxicity to F1 from all exposures,F0 exposure only,and F1 exposure only to TCC.The main findings are as follows:1.Through the 96-hour acute exposure test,revealed the different toxicity of TCC to zebrafish embryos,larvae,juveniles and adults,and the lethal sensitivity at different life stages was larvae(32.59 ?g / L).,Juvenile(76.83 ?g / L),adult(166.89 ?g / L),and embryo(200.63 ?g / L),indicating that the zebrafish larva stage is most sensitive to TCC.2.Through short-term exposure tests,reveal the effects of TCC on multiple aspects of zebrafish larvae: affecting larvae's antioxidant markers superoxide dismutase(SOD),catalase(CAT),and glutathione S-transferase(GST)activity,increased levels of reactive oxygen species(ROS)and malondialdehyde(MDA)cause oxidative damage;interfere with the expression of antioxidant-related genes(cat1,sod1,gstr,nrf2,keap1 and cox)It indicates that the balance of the antioxidant system is disrupted;it affects the content of estradiol(E2)and yolk protein(VTG)in larvae,and interferes with reproductive endocrine-related genes star,cyp11,3?-hsd,cyp17,17?-hsd,cyp19 a,and vtg expression;interfering with the expression of apoptosis-related genes bax,bcl2,apaf1,cas9 and cas3,and induce apoptosis.3.By exposing adult zebrafish(F0)to environmentally relevant concentrations(0,1.2,6,30 ?g / L)of TCC for 21 d,collect embryos and raise them to(F1)to 96 hpf.The effects of TCC exposure on the offspring: the female parents' spawning and gonad body mass constant(GSI)are significantly reduced;parental exposure to TCC significantly increases the mortality and deformity of the offspring,and leads to the offspring's body Shorter length and premature incubation time;cat1 expression was significantly down-regulated and apoptosis-related genes p53,cas9,and cas3 were significantly up-regulated in offspring,indicating that oxidative stress in offspring of parental TCC exposure may further induce apoptosis;the expression of cyp19 b,vtg1 and vtg3 in the offspring was significantly up-regulated,indicating that the offspring's reproductive endocrine was disturbed.