MYCOSPORINE-LIKE AMINO-ACIDS PROVIDE PROTECTION AGAINST ULTRAVIOLET-RADIATION IN EGGS OF THE GREEN SEA-URCHIN STRONGYLOCENTROTUS-DROEBACHIENSIS

A photoprotective role of ultraviolet radiation-absorbing mycosporine- like amino acids (MAAs) in eggs of the green sea urchin Strongylocentr otus droebachiensis was demonstrated by comparing UV-induced delays in the first division of embryos having either high or low concentration s of MAAs, Embryos from adult urchins fed Laminaria saccharina (no MAA s) had low concentrations of MAAs and experienced a significantly long er UV-induced delay in cleavage (25.1%) than MAA-rich embryos from adu lts fed Mastocarpus stellatus (12.8% delay) or a combination diet of b oth macroalgae (12.3% delay). Collectively, these embryos displayed a significant inverse logarithmic relationship between MAA concentration and percentage cleavage delay, so that the greater the MAA concentrat ion in the eggs, the less they were affected by UV radiation. This is the first study to examine such MAA photoprotection during acute UV ex posure using dietary manipulation of cellular MAA concentrations with no prior UV exposure of the experimental subjects, Concentrations of M AAs were also measured in unfertilized eggs, blastulae, gastrulae and early pluteus larvae, providing the first documentation of changes in MAAs during embryological and larval development. The concentration of shinorine (the principal MAA in the eggs) did not change during short -term UV exposure lit vivo or long-term exposure in vitro; such photos tability is a useful attribute of a natural sunscreen.