Monohydroxylated polycyclic aromatic hydrocarbons influence spicule formation in the early development of sea urchins (Hemicentrotus pulcherrimus)

We previously demonstrated that monohydroxylated polycyclic aromatic hydrocarbons (OHPAHs), which are metabolites of polycyclic aromatic hydrocarbons (PAHs), act on calcified tissue and suppress osteoblastic and osteoclastic activity in the scales of teleost fish. The compounds may possibly influence other calcified tissues. Thus, the present study noted the calcified spicules in sea urchins and examined the effect of both PAHs and OHPAHs on spicule formation during the embryogenesis of sea urchins. After fertilization, benz[a]anthracene (BaA) and 4-hydroxybenz[a]anthracene (4-OHBaA) were added to seawater at concentrations of 10− 8 and 10− 7 M and kept at 18 °C. The influence of the compound was given at the time of the pluteus larva. At this stage, the length of the spicule was significantly suppressed by 4-OHBaA (10− 8 and 10− 7 M). BaA (10− 7 M) decreased the length of the spicule significantly, while the length did not change with BaA (10− 8 M). The expression of mRNAs (spicule matrix protein and transcription factors) in the 4-OHBaA (10− 7 M)-treated embryos was more strongly inhibited than were those in the BaA (10− 7 M)-treated embryos. This is the first study to demonstrate that OHPAHs suppress spicule formation in sea urchins.