| Environmental hormones are also known as endocrine disruptors, Its metabolites or intermediate derivatives will eventually enter aquatic ecosystems through different routes. recent years the using of aquatic organism to assess risk of environmental hormone become one of focus research in the areas of aquatic environment. Rotifer plays an important role in the ecological system. And because of their small size, fast reproduction, short life cycle, sensitive to the toxic material and can be easily obtained, rotifer has been used as test animal in ecotoxicology, This paper analyzes three kinds of reagents:flutamide, estradiol and testosterone as subject hormones, they were androgen antagonist, estrogen and androgen, with rotifer Asplanchna brightwelli as subject rotifers. It is known that some vertebrate reproductive hormones have effects on rotifer reproduction, but little is known about their effects in combination. This motivated us to examine the effects of waterborne flutamide(F), testosterone(T), and estradiol(E) on reproduction of the rotifer Asplanchna brightwelli, comparing exposures to single hormones and mixtures hormones, provide new ideas for assess environmental hormone risk.The main results were as follows: 1. single factor experimentAsplanchna brightwelli were treated by three reagents separately at different concentrations, the number of neonates produced by mother females and the number of original test individuals alive were recorded, the neonates were removed at intervals of 12 hours. The original rotifers alive were transferred into freshly prepared test solution at intervals of 24 hours. The experiments were conducted in constant incubator at 25± 1 ℃ until each individual of every cohort died.In single hormones tests, the Intrinsic rate of population increase(rm), net reproductive rate(Ro), and generation time(T) were significantly affected by increasing concentrations of three hormones. In general, these parameters were decreased with increasing concentration of three hormones. A similar survivorship pattern was found between F0.5, F1 and control. In general, survival curve of the control group is one of A-type curve pattern, this trend gradually changed from A-B-C type as the concentration of the flutamide in the medium increased from 0.5 to 8 mg/L. At any given toxicant concentration, the negative impact of the toxicity of the flutamide was higher at higher concentration. In general, most cohort populations showed nearly normal distribution patterns of reproduction at lower concentration. At any given concentrations, increase in the flutamide concentration resulted in decreased age-specific reproduction, especially at the concentration of 4 and 8mg/L, the reproduction of Asplanchna brightwelli were deeper inhibited, the rotifers did not produce an offspring at the concentration of 8mg/L.The trend gradually changed from A-B-C type as the concentration of the testosterone in the medium increased from 2 to 8 mg/L. The similar trend had been found in estradiol treatments, the rotifers exposed to the medium at the concentration of estradiol (1,2,4 and 8mg/L) appeared lower age-specific reproduction compared to the control, above all, the age-specific reproduction were obviously restricted at the concentration of 4 and 8 mg/L.About the selected life history variables of Asplanchna brightwelli in relation to different concentrations of flutamide, estradiol and testosterone. Overall, Net reproductive rate(Ro) decreased with increasing concentration of three hormones. The difference is decline rate of Ro is faster when the rotifers exposed to estradiol-containing medium than exposed to other two hormones. The maximum of Ro is appeared at the concentration of 0.5mg/L flutamide, but not significant (P>0.05). Whereas, the minimum (P<0.01) of R0 is presented at treatment(F8), the rotifers did not give birth a neonate at this concentration. Generation time(T) and Intrinsic rate of population increase(rm) is lower than control and the corresponding values are decreased with increasing concentration of three hormones too. Ro, T and rm were all significantly affected by the increasing concentration of three reagents (P<0.05).2. Hormone combination experiment(1) Hormone flutamide and estradiol combined with testosterone experimentAbout the selected life history variables of Asplanchna brightwelli in relation to different concentrations of testosterone combined with flutamide. In terms of whole life table, Ro, T and rm decreases with the increase of the concentration of flutamide. Ro of T0.5 combined with flutamide (0.5,1,2,4 mg/L) are higher than the medium containing flutamide individually (P>0.05).About the selected life history variables of Asplanchna brightwelli in relation to different concentrations of testosterone combined with estradiol. In general, Ro and T are decreased with increasing concentration of estradiol (P<0.05). However, in the test of E0.5(T0,T0.5,T1,T2,T4,T8), Ei(T0,T0.5,T1,T2,T4,T8), E2(T0,T0.5,T1,T2,T4,Ts), E4(T0,T0.5,T1,T2,T4,T8), E8(T0,T0.5,T1,T2,T4,T8),we found Ro of T0.5 combined with E0.5(p<0.0.5), E1, E2 and E4(p<0.05)are higher than E combined with To, except the treatment of E8T0.5, but not significant (p>0.05).(2) Hormone combination experiment of flutamide and estradiol combined with testosterone at a total concentration of 8 mg/LIn all treatments, the Ro, T and rm values of treatments which containing estradiol at low levels are significantly higher than that of high levels (P<0.05). Likewise, corresponding parameters are significantly higher when the medium at a low concentration of flutamide compared to it at a high concentration too (P<0.05). In addition, remove the control group, the maximum of Ro is appeared in the treatment of E1T7 and F1T7, the corresponding values were 4.8 and 6.8. T maximums (37.24h, 51.29h) are also appeared in the experimental group E1T7 and F1T7.This article, we try to use predatory rotifer to evaluate estradiol, testosterone and its antagonist flutamide single and joint effects of rotifer population dynamics, single-factor tests found R0, T and rm were significantly affected by the concentration of three reagents (P<0.05). we used two different mixed modes to mix the hormones. As is revealed in hormones combination experiments, Ro and T are more affected by flutamide and estradiol. Asplanchna brightwelli are more sensitive to flutamide and estradiol compared to testosterone, this result were consistent with the results of single-factor test. From the experimental can be found in some combination concentration, the testosterone can resist toxic effects of flutamide on rotifer and from the result can revealed androgen(testosterone) combined with estradiol showed a synergistic effect on some combination of concentration. |
