Inhibitory effects of neurotoxin β-N-methylamino-L-alanine on fertilization and early development of the sea urchin Lytechinus pictus

Neurotoxin beta-N-methylamino-L-alanine (BMAA) has been widely detected in diverse aquatic organisms and hypothesized as an environmental risk to neurodegenerative diseases in humans. However, the knowledge of its toxicity to marine organisms requires attention. In the present study, embryos and sperm of the sea urchin, Lytechinus pictus, were used to assess the toxicity of BMAA. Effects of BMAA on fertilization and development of sea urchin embryos were measured, and its impacts on efflux transport of sea urchin blastula were also assayed. Results demonstrated that the fertilization and development of embryos were significantly inhibited by high concentrations of BMAA above 300 mu g L-1. The EC50 values indicated by active swimming larvae and total larvae numbers at 96 HPF (hours post fertilization) were 165 mu g L-1 (1.4 mu mol L-1) and 329 mu g L-1 (2.8 mu mol L-1), respectively. Additionally, sperm exposed to BMAA for 10 min significantly reduced the fertilization ratio of sea urchin eggs. However, the ABC transport activity on the cytomembrane of sea urchin blastula was not inhibited by the presence of BMAA at 50 mu g L-1, even up to 500 mu g L-1. Abnormal division and developmental malformations occurred at different developmental stages for sea urchin embryos exposed to BMAA at 500 mu g L-1. The inhibitory effects of BMAA on sea urchin embryos were reported at the first time in this study, for which the toxicological mechanisms will be explored in future studies.