| The hazard of endocrine disrupting chemicals(EDCs)to aquatic ecological system has raised more and more concerns in recent years.As a typical model organism in the water-sediment system,chironomids is extremely sensitive to changes of environmental factors.In this paper,BPP was used to study Chironomus tentans the early response of the molecular biology level(cell level,protein level,gene level)and responses of individual level(life cycle toxicity).The results are as follows:(1)In this study,the embryos and larvae of the Chironomids were exposed to BPP for 72 h and 48h respectively,the results showed that the 72h-EC50 of BPP on embryos was 0.81 mg/L,the 48h-EC50 of BPP on the first-instar larvae was 0.12 mg/L,and the fourth-instar larvae was 0.47 mg/L.The results indicated that the larvae of the first-instar was more affected than the embryos of the Chironomids,and the larvae of the first instar were the more sensitive to the BPP.(2)The NOEC value of BPP on the total eclosion rate of P generation tentans was 0.015 mg/L,and the eclosion rate of male tentans was 0.05 mg/L,which had no significant effect on the eclosion rate of female.The NOEC value of total development Was 0.015 mg/L,the NOEC values of both sexes were 0.015 mg/L,and the P generation of both sexes and fecundity did not change significantly.The NOEC values of the FI generation with eclosion rate on BPP was 0.003 mg/L,positive rates of females and males were 0.05 mg/L and 0.015 mg/L,The values of NOEC of female and male chironomus were 0.003 mg/L.Compared with the parents tentans,the total female-male ratio of tentans changed significantly at 0.161 mg/L,that is,the NOEC value was 0.05 mg/L.From the data we can see that the survival rate of P generation tentans is higher than that of offspring.Because of the bioaccumulation,more BPP toxic substances accumulate in the offspring,resulting in higher offspring's sensitivity to BPP than to their parents generation,so F1 generation had a much lower NOEC value than that of its P generation.Therefore,BPP played a certain role in the sex differentiation of C.tentans,indicating that BPP has estrogenic effects.(3)In the apoptosis test,the fluorescent part located on the head of the chironomid mosquito was more obvious with the increase of concentration and time of BPP exposure.Compared With the reference figure,it can be seen that the tentans head emitting the fluorescent color is the endocrine system,the larvae cells were stimulated injury because of the toxicity of BPP,resulting in more cells apoptosis,and embroys fluorescence effect is higher than larvae,its indicated that the impact of embroys was more higher than four-instar larvae,and BPP does have a certain impact on the endocrine system of tentans.(4)The activities of CAT and SOD were significantly induced by 24 h BPP exposure,and a similar trend was observed between CAT and SOD.There was a high positive correlation between the two indicators,indicating that SOD and CAT behaved in harmony as the first defense line of enzyme.In short-term test,GST activity in larvae showed a downward trend,its indicated that BPP inhibited the activity of GST enzyme,it was inhibited significantly that probably enhancing the toxicity of the BPP to Chironomids larvae.(5)BPP could significantly induce ECR,Usp and E74 genes in embroys and larvae.After 24h exposure,ECR,Usp and E74 genes in larvae were all significantly up-regulated at 0.5 mg/L,ECR and Met genes Also increased significantly at 0.5 mg/L.With the increase of exposure time,the ECR,Usp and E74 genes were significantly up-regulated at 0.05,0.1 and 0.1 mg/L of embroys in 48h exposure.ECR and Met genes of larvae were significantly up-regulated at 0.1,0.5 and 0.1 mg/L,it showed that the embroys were more sensitive than the larvae,and there was a downward trend of the Met gene in embroys and larvae.Therefore,it is speculated that BPP can interfere with ecdysone and juvenile hormonal regulation system of tentans,it may belong to Environmental endocrine disruptors. |
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