| Recently,endocrine disrupting chemicals(EDCs)are causing an increasingly serious pollution problem to the human and wildlife all over the world.These chemicals have the ability to mimic or resist the action of endogenous hormones,and affect growth, development and reproduction and so on.At present,some research work about the single chemicals effects on fish were focoused on mature fish,and less attention has been given to the effect in juvenile fish.Furthermore,the wild environment is complex, diversification and the EDCs always interact with each other,their fuction and mechanisms are very different from the single chemicals.In this paper,we used 4-nonylphenol(NP)andβ-naphthoflavone(βNF)as two antagonism EDCs to study the estrogenic and antiestrogenic effects on juvenile Gobbid fish.This paper included two parts,first,the long-term NP exposed effects on the sex differentiation,testis development and VTG induction were studies;second,we select VTG, ethoxyresorufin-O-deethylase(EROD),and glutathione S-transferase(GST)as biomarkers to study the effects of NP andβNF on juvenile Gobbid fish.The ultimate aim was to provide basic dates to further understanding the effects of EDCs on juvenile fish extoxicology.1 Effect of NP on VTG induction in juvenile Gobbid fish(Odontobutis potamophila)VTG has been used as an important biomarker for assessing the estrogenic potency in fish and other oviparous vertebrate.This paper reported the effect of NP on VTG in Gobbid fish by ELISA and semi-quantitative reverse transcription-polymerase chain reaction(RT-PCR).The larvae were exposed to 100μg/L,300μg/L,500μg/L(nominal concentrations)NP.The period lasted 150 days.Plasma VTG concentrations and its mRNA level of Gobbid fish were measured.The results showed:plasma VTG concentration and its mRNA level increased with the NP concentration,this effect was dose dependent,it was greatly significant difference in the NP500μg/L exposure group(P＜0.001)with the control group.So the concentration of VTG and its mRNA level could be the appropriate endpoints for screening environmental estrogens.2 Effect of long-term NP exposed on the gonadal differentiation and development in Gobbid fish(Odontobutis potamophila)The effect of environmental estrogen compound,4-nonylphenol(NP)on goandal differentiation and development in Gobbid fish was studied by using histological techniques.The larvae were exposed to 100μg/L,300μg/L,500μg/L(nominal concentrations)NP,blank control group and vehicle control group.The period lasted 150 days,and then the gonads were examined with histological methods.The results showed that the process of gonadal differentiation developed neutron-states at first,and then directly formed ovary and testis.Compared with control group,there were no statistically significant departures from sex ratio of 1:1 at any concentration groups of NP,but the number of undeveloped testes was increased.The percentage of undeveloped testis were 20%at 300μg/L NP and 22%at 500μg/L NP respectively,Furthermore,Not only testicular development was suppressed in the exposed group,but also histopathological changes were also observed within the testes.Increased testicular fibrosis and necrotic testicular cells at the high concentration of NP.3 The effects of NP andβNF combined on VTG in juvenile Gobbid fish(Odontobutis potamophila)This study investigated the effects of combined with NP and polycyclic aromatic hydrocarbons(PAHs)like compound—βNF on vitellogenin(VTG)induction in juvenile Gobbid fish by using ELISA and real-time RT-PCR.The juvenile fish was exposed to NP100μg/L,NP200μg/L,NP300μg/L;NP200μg/L+βNF30μg/L,NP200μg/L +βNF60μg/L,NP200μg/L+βNF120μg/L(nominal concentrations).Each experimental exposure was for 28 days,plasma VTG and liver VTG mRNA were measured in order to evaluate the effect of chemicals on fish.The results showed:The estrogenic effect of NP was inhibited byβNF,the plasma VTG protein ofβNF30μg/L+NP200μg/L,βNF60μg/L +NP200μg/L andβNF120μg/L+NP200μg/L were 36%,40%,35%respectively over the NP200μg/L group,and have greatly significant difference(P＜0.001),and the gene expression was inhibited.The VTG mRNA was also restrained in theβNF and NP combined groups(P＜0.05).So there was antiestrogenic affection in the combined groups.4 The effects of NP andβNF on biotransformation enzyme system in juvenile Gobbid fish(Odontobutis potamophila)This paper investigated the effects of NP andβNF on biotransformation enzyme system in juvenile Gobbid fish.The fish was exposed to NP100μg/L,200μg/L,300μg/L;βNF30μg/L,60μg/L,120μg/L;NP200μg/L+βNF30μg/L,NP200μg/L+βNF60μg/L, NP200μg/L+βNF120μg/L(nominal concentrations)and blank control group.Each experimental exposure was for 28 days,and then EROD and GST activities were measured in order to evaluate the effect of environmental chemicals on fish.The results showed:first,NP can inhibit the EROD activities,there was a difference at the NP200μg/L and 300μg/L group(P＜0.05)with control group.βNF30μg/L andβNF60μg/L can improve the EROD activity,but it was no difference with control group,the activity declined at theβNF 120μg/L group,the induced mechanisms of enzyme may be destroyed byβNF at the high concentration.When mixed NP andβNF,the EROD activities get back to the level of control group.Second,the GST activity of the NP group and theβNF group was declined,when they combined,the GST activity level restored the control group.Whether NP andβNF single or combined,the GST activity didn't increase,this may be some other enzymes active in this pase,such as UDP-glucuronide transferase (UDP-GT).
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