Developmental toxicity of 3,4-dichloroaniline on rare minnow (Gobiocypris rarus) embryos and larvae.

ABSTRACT

Gobiocypris rarus is a freshwater cyprinid, which possesses lots of attractive features (short life cycle, high fecundity, and especially the transparent trait during early life stage) that make it a suitable model in aquatic toxicity tests. In this study, the effects of 3,4-dichloroaniline (3,4-DCA) on the early life stages of G. rarus were measured. As endpoints, normal developmental parameters (survival rate, malformation rate, total body length and average heart rate) as well as biomarker genes (stress response (hsp70), organizer function and axis formation (wnt8a), vascular system development (vezf1), detoxification (cyp1a) and endocrine disruption (erα)) in the developing embryos and larvae were recorded during a 72 h exposure. The results revealed that reduced survival rate, increased malformation, changes in heart rate and total body length provide a gradual dose-response relationship, values of 72 h LC(50) were 4.146 (3.665-4.713) mg L(-1) for embryos and 1.088 (0.832-1.432) mg L(-1) for larvae. The developmental biochemical biomarkers are very promising tools to determine the severity of toxicants in the growing G. rarus embryos and larvae, even at a concentration of 1% for LC(50). Gene expressions of wnt8a and cyp1a in embryos were highly up-regulated (more than 100-fold) after exposure to 3,4-DCA. Overall, the present study points out that 3,4-DCA is high toxic to the early development of G. rarus, and offers a practicable and highly sensitive bioassay for the general assessment of chemical toxicity.