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Fig. 1
BPA treatment induces otolith abnormalities. A: BPA induced otolith malformation is dose dependent. Embryos were treated with different concentrations of BPA from 5 hpf onwards. Black bars represent embryos showing no otolith abnormalities, red bars represent treated embryos showing otolith abnormalities. (*: P < 0.01, Fisher test after Bonferroni correction). B: Anterior otolith (ao, upper left) and posterior otolith (po, upper middle) of control embryo and ao (lower left) and po (lower middle) of embryos treated with 70 µM BPA from 5 to 50 hpf showing otolith aggregation. In some rare cases a single otolith (upper right) or extra otolith (eo lower right) are observed. C: Upper panel: control embryo at 50 hpf (Upper right: close up of the otic vesicle). Lower panel: overall shape of BPA treated embryos form 6-50 hpf resembles control embryos, but display otolith aggregates (arrow). Lower right: close up of the otic vesicle in a BPA treated embryo form 24-50 hpf showing normal otoliths. D: After 75 hours of exposure, the concentration of BPA measured in embryos is 0.7 µg equivalent per mg fresh weight and 0.22 µg of BPF equivalent per mg fresh weight; see also Figure 2 C-E. E: BPA induces malformation of the otic vesicle in Xenopus embryos. Xenopus embryos were exposed to BPA (5 or 10 µM) from stage NF 18 to stage NF 40 (48 h) and examined at stage NF 45. The upper panel shows the morphology of the otoliths (or otoconia 73]) in control and BPA treated embryos. Note that 5 and 10 µM of BPA induce a progressive reduction in the size of the otoconia. The lower panel shows the semi-circular canals with a reduction in the distance between the two semi circular canals (arrowheads) induced by BPA. Similarly, the morphology of the developing semi circular canals is flattened under BPA treatment.