PT14 Toxicity of Mixtures
Exhibit Hall
8:00 AM - Tuesday
(PT228) Effects of binary mixtures of xenoestrogens on the reproductive fitness of zebrafish (Danio rerio).
Lin, L1, Janz, D1, 1 Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
ABSTRACT- The present study evaluated effects of binary mixtures of two common xenoestrogens on sex ratios, gonad morphology, vitellogenin induction, heat shock protein 70 (hsp70) expression, gonadal cell death, and breeding success in a partial life − cycle test with zebrafish (Danio rerio). Fish were exposed from 2 to 60 days post-hatch (dph) to environmentally relevant concentrations of 17
−ethinylestradiol (EE2) (1 or 10 ng/l nominal), 4−nonylphenol (NP) (10 or 100 
g/l nominal), binary combinations of EE2 and NP ( 1 ng/l + 10 g/l, 1 ng/l + 100 g/l, 10 ng/l + 10 g/l, or 10 ng/l + 100 g/l nominal) or solvent control (acetone; 0.1% v/v) in a static−renewal system with replacement every 48h. At 60 dph, 40 fish from each treatment were euthanized for evaluation of length, weight and condition factor. Initial statistical analysis showed no significant differences in mortality between solvent control and treatment groups. Significant increases in condition factor of treatment groups EE2 − 10 ng/l, EE2 − 10 ng/l + NP − 10 g/l, and EE2 − 10 ng/l + NP − 100 g/l were observed when compared to solvent controls (Dunn′s multiple comparison, all with p < 0.001). Subsequent histological examination of gonad development, condition factor, vitellogenin, hsp70 and cell death will be performed. The remaining fish will be reared in clean water until adulthood (120 dph), at which time breeding studies will be conducted to evaluate reproductive fitness via assessment of percent of viable eggs, hatchability, and swim−up success of fry.
Key words: 4−nonylphenol, zebrafish (Danio rerio), 17−ethinylestradiol, mixture