Rare minnow Gobiocypris rarus is a Chinese cyprinid. It has many attractive features that make it a Suitable organism in aquatic toxicity tests, including small size, wide temperature range, easily being cultured in laboratory, large amount of eggs and short life cycle. It has also been reported this species is susceptible to heavy metals arid other xenobiotics. However, little has been known about the endocrine disruptions of xenoestrogens in this native Chinese species. The aim of the study was to investigate the effects of diethylstilbestrol ( DES) exposure in early life stage on development arid reproduction of rare minnow. Rare minnow were raised in the laboratory. They were maintained in a light/dark cycle of 14:10 h at 23-26 degrees C and fed once a day. To start the test with DES,embryos (< 8 h postfertilization) were collected from at least three spawnings as required by standard protocol. Based oil a 28 (lays preliminary exposure Study, nominal concentrations of DES at 10 arid 100 mu g/L, were selected for this study. Rare minnow were exposed to these two concentrations of DES from newly fertilized embryos to 23 (lays post hatch. The mortality, abnormal behavior and appearance of the larvae were recorded (hiring the exposure. At the end of exposure. fish were sampled to measure body weight, body length arid then stored at -80 degrees Cfor VTG analysis and Total T-4(TT4)measurement. At 24 days posthatch, rare minnow were transferred to clean water. At 175 days posthatch, 15 fish were sampled to measure body weight, body length and their stored at -80 degrees C for Vtg analysis. Four mating pairs were selected from control group and DES-exposed groups for examination Of fecundity and fertility. At the end of exposure, it was found that exposure to DES caused all increase in mortality arid vitellogenin ( VTG) levels. Growth was significantly inhibited in the fish exposed to DES. After a five-month period culture in clean water, the sex ratio male:female observed was changed from 46:54 in controls to 31:69 at 10 mu g/L., DES and 33:67 at 100 mu g/L DES. Reproductive capability was depreciated in the DES-treated fish as measured by fertility of eggs, hatchability of eggs and survival of F, larva. The growth arid VTG level had a significant change in the DES-treated fish when compared to the control group. The results indicate that exposure to DES in early life stage call cause adverse effects oil development arid reproduction. It suggests that rare minnow is suitable for early life stage test in assessing the environmental impact of endocrine-disrupting chemicals.
Zhong Xue-Ping; Xu Ying (xuying@ihb.ac.cn) ; Liang Yong; Liao Tao; Wang Jian-Wei.Effects of diethylstilbestrol exposure in early life stage on development and reproduction in rare minnow, Gobiocypris rarus,Acta Hydrobiologica Sinica,2005,29(6):667-672
