[Study on toxic effects of ammonia on embryonic and yolk-sac stage larvae of rare minnow].

To investigate the toxicity to fish which were exposed to ammonia during early life stages. This study choose rare minnow which is unique to China for experimental subject. Representative toxicological endpoints were observed and recorded during the development of embryo and yolk-sac stage larvae. Meanwhile, selected ammonia transporter protein Rhbg gene as a toxicity parameter to reflect the changes of rare minnow embryos Rhbg gene expression. The result shows that ammonia we have chosen in this research had an influence on many toxic effects including the hatching rate of fry, mortality rate, the slowing of heart rate and arrhythmia, unformed functional swim bladder, the decreasing of body length and weight and the occurrence of pericardium and yolk-sac edema etc. But other toxicological endpoints have relatively weak effect. The ammonia also affect the Rhbg gene expression changes, especially that of Rhbg gene at 72 hours post-fertilization distinctly. Rhbg may have important functions to facilitate ammonia transport during rare minnow embryo stages.