Interference Effect And Mechanism Research Of Nonylphenol On Intergeneration Zebrafish

Nonylphenol,arising from the degradation of nonylphenol ethoxylates,is a highly cost effective surfactant usd in industrial,commericial and household applications.NP is a widespread distributed in aquatic system caused by household gaebage and chemical industry released in environment.NP is exogenous estrogen,which can bind to estrogenic receptors like endogenous estrogen mimics.Meanwhile,NP has potential to interfere with hormonal regulatios and homeostasis,and consequently cause health effects in aquatic organisms and humans.Therefore,we aimed to the effect of longtime exposure of NP on three generation zebrafish.The objectives of the present study were the experiment of NP on growth and development in intergeneration zebrafish,NP on reproduction toxicity in intergeneration zebrafish,and NP on sexual differentiation in zebrafish.The results could provide the data support for potential toxicity effect and intergeneration endocrine disruption effect of NP on teleost.NP significantly inhibited the length and weight of zebrafish in three generations.With the increasing generations,the inhibition effect was increased.Moreover,low concentration of NP had a potential toxic effect,as the 20 μg·L^-1 of NP inhibited the length and weight in F2 generation zebrafish.Meanwhile,NP could lead to teratogenicity and lethality in zebrafish.Teratogenicity was observed in 2 μg·L^-1 of NP in F3 generation zebrafish.This phenonmenon explained that NP has a strong genetic toxic effect through three generations.The toxicity degrees of NP on growth and development in three generation was F2>F1>P。The long-term exposure of NP inhibited the fertilization rate and hatching rate in zebrafish.The fertilization rate and hatching rate significantly decreased in the high treated group,but greatly improved in F2 generation.Histopathological results showed that NP significantly damage to the testis structure of male zebrafish,but ovary in female zebrafish.The situation of testis injury were spermatogenic cell reduced,Sertoli cells reduced and spermatogenic spermatids fused.Further study showed that non-cell area of F2 generation was significantly lower than F1 generation.This results had confirmed that the F2 generation zebrafish adapt the NP.The toxicity degrees of NP on testis in three generation was F1>F2>P。NP could interfered the sexual differentiation of zebrafish.Eighty percent of females in the 20 μg·L^-1 of NP in the F1 generation,but no difference with F2 generation.The genes of sex differentiation showed that cyp19a1 a and esr1 genes could indicated the female differentiation.However,in the F2 generation,the regulation of cyp19a1 a had no difference with control.Therefore,the cyp19a1 a gene could be used as biomarker for female differentiation in 15-40 dpf in zebrafish.NP could interfered the regulation of reproduction genes and estrogen receptor gene in HPG axis.In brain,the gnrh2 gene was up-regulated gradually with increasing generation,and the lh gene was down-regulated in males and up-regulated in females.In gonad,the fshr,lhr and cyp19a1 a genes were up-regulated in the P and F1 generations and down-regulated in the F2 generation.The esr1 gene was downregulated in males,while up-regulated in P and F1 generation and down-regulated in F2 generation in females.It is presumed that reproductive ability had tolerance in F2 generation under long-term exposure NP to zebrafish.In sum,the zebrafish appeared a complex pattern of regulation in long-term exposure for NP.The zebrafish chosed the tolerance and adaptability of reproduction,like fertilization rate and hatching rate increased in F2 generation,and ignored their own survival,like offspring length and weight decreaed.This pattern of regulation might be a life strategy for zebrafish to adapt the contaminative environment.