Hormetic Effects of Cerium, Lanthanum and Their Combination at Sub-micromolar Concentrations in Sea Urchin Sperm

Rare earth elements (REEs) cerium (Ce) and lanthanum (La) and their combination were tested across a concentration range, from toxic (10(-4) to 10(-5) M) to lower concentrations (10(-6) to 10(-8) M) for their effects on sea urchin (Sphaerechinus granularis) sperm. A significantly decreased fertilization rate (FR) was found for sperm exposed to 10(-5) M Ce, La and their combination, opposed to a significant increase of FR following 10(-7) and 10(-8) M REE sperm exposure. The offspring of REE-exposed sperm showed significantly increased developmental defects following sperm exposure to 10(-5) M REEs vs. untreated controls, while exposure to 10(-7) and 10(-8) M REEs resulted in significantly decreased rates of developmental defects. Both of observed effects-on sperm fertilization success and on offspring quality-were closely exerted by Ce or La or their combination.