Octylphenol Rana Larval Growth And Development And Its Transfer-generation Effect

Belong to nonionics, octylphenol (OP) is widely used in the manufacture of detergents, paints, pesticides, cosmetics products with characters of hard degradation, lasted toxic effects and bioaccumulation in aquatic animals. It is investigated that OP is a class of endocrine-disruption chemicals (EDCs) with strong estrogenic activities, which has potential to cause significant endocrine disruption effects on development, gonadal differentiation and hormone in contemporary animals and their offsprings. In this research, given the great sensitivity of frogs Rana chensinensis to environmental contaminants at early developmental stage, tadpoles were considered to be model animals to study acute toxicity effects and effects of OP on development, gonadal differentiation, expressions of P450arom in gonads. Moreover, frogs R. chensinensis were exposed to study trans-generation effects of OP. The aim of this research was to investigate the endocrine disruption mechanism of EDCs to amphibians, and provid scientific evidence for protection of ecology environment.To evaluate the acute toxicity effects of OP to tadpoles R. chensinensis, tadpoles were exposed to 5.0×10-7～5.0×10-6 mol·L-1OP under static conditions at stage 26 for 96h, and the median lethal concentrations (LC50) and safe concentrations (SC) were calculated. To evaluate the effects of OP on development, tadpoles were continuously exposed to 10-7,10-8,10-9mol·L-1 OP and 10-7,10-8mol·L-1 estradiol (E2) at stage 26 until metamorphosis of 70% tadpoles. Then weight and length of tadpoles were examined at 20,40d and after metamorphosis of 70% tadpoles respectively, development time was recorded at stage of 38,42 and 46 respectively, and survival rate, sex ratio and expression of P450arom in gonads of young frogs were examined at the end of experiments.To evaluate the trans-generation effects of OP, female adults R. chensinensis were exposed to 10-7,10-8,10-9mol·L-1OP and 10-7,10-8 mol·L-1 E2 for 60d. Then survival rate, quantity of spawn of female adults and hatchability of F1 generation tadpoles were recorded. Moreover, their tadpoles at stage 26 were separated into two exposure groups:1.Continuous exposure group (treated with 10-1 10-9 mol·L-1OP and 10-7,10-8 mol·L-1E2); 2. Mother exposure group (normal feeding). Then weight and length of tadpoles were examined at 20,40d and after metamorphosis of 70% tadpoles respectively, development time was recorded at stage of 38,42 and 46 respectively, and survival rate, sex ratio and expression of P450arom in gonads of young frogs were examined at the end of experiment. The results and conclusions are listed as follows:1. Results of acute toxicity experiment showed that the LC50 values of OP were 3.55×10-6, 2.96×10-6,1.90×10-6,1.52×10-6 mol-L-1 for 24,48,72 and 96h respectively, and safe SC value of OP was 1.52×10-7 mol·L-1. The results indicated that OP had the acute toxicity effects on tadpoles, and the death rate of tadpoles increased with OP concentration ascend and prolong exposed time.2. Results of sub-chronic experiment showed that OP did not affect mortality of tadpoles under SC, but decreased body weight and length, delayed metamorphosis time, resulted in development malformation of tadpoles, increased female ratio and induced expression of P450arom in gonads of young frogs. It was indicated that OP had the similar inhibition effects on growth and development and estrogen effects on gonadal differentiation of tadpoles as well as E23. Results of trans-generation effects experiment showed that OP and E2 did not affect hatchability and survival rate of F1 generation tadpoles under SC, but decreased body weight and length, delayed development time, caused feminization and intersex formation and induced expression of P450arom in gonads of young frogs.These results indicated that OP and E2 had the trans-generation effects on growth and development, gonadal differentiation and expression of P450arom in gonads of tadpoles R. chensinensis, which increased with OP and E2 concentrations ascend.In conclusion, OP appears to directly result in death for tadpoles R. chensinensis at higher concentrations, and can inhibit growth and development, disrupt normal gonadal differentiation, cause feminization and intersex formation and induce expression of P450arom in gonads of young frogs at lower concentrations, which can be transmitted from female adults to their offsprings to interference their growth and development.