Developmental disturbances caused by polychlorinated biphenyls in zebrafish ( Brachydanio rerio)

A selection of four PCB congeners (PCB#60, PCB#104, PCB#173 and PCB#190) and estradiol 17-β were tested on zebrafish for their effect on early embryo development. The females were kept separately in 21 aquaria and injected with the different compounds (1 μmol kg −1) or peanut oil. Ten days after injection the females were mated with uninjected male zebrafish and the eggs were collected and kept at 28 °C. It was observed that injection of estradiol 17-β (1 μmol kg −1 w.w.) and PCB#104 (2,2′,4,6,6′-pentaCB) resulted in high mortality before hatching. Injection of PCB#60 (2,3,4,4′-tetraCB) also resulted in high mortality and this was found to be due to impaired hatching. PCB#104, PCB#173 (2,2′,3,3′,4,5,6-heptaCB) and estradiol 17-β led to posterior malformations and edemas. PCB#190 (2,3,3′,4,4′,5,6-heptaCB) treatment led to slow embryonic growth and anterior malformations. Embryos of control fish injected with peanut oil had a better than 90% survival rate and showed no malformations. Following spawning the female fish were kept for an additional 20 days, after which they were sacrificed and the liver was removed. RNA was extracted from the livers and screened for estrogen receptor (ER) induction using zebrafish ER DNA-binding-domain cDNA as a probe. Increased ER mRNA levels were observed in estradiol 17-β and PCB#104 injected females. These results indicate that some of the effects seen with PCB#104 may be due to estrogen like effects on the embryos.