Effect of UV Treatment on Early Development of Sea Urchin Embryos

Nicole Porter 4/26/01

Objective:
To test the effects of UV radiation at 254nm on Sea Urchin embryo development after radiation at the 2-cell stage.

Background:
Sea Urchins exhibit radial holoblastic cleavage. The first and second cleavages are perpendicular to one another

and go through the animal and vegetal poles. The subsequent cleavages separate the cells into mesomeres,

macromeres, and micromeres. Sea Urchins undergo formation of the blastula and gastrulation before developing into a

mature embryo.

UV light is harmful to many organisms just as it is harmful to humans. Many eggs of marine animals including sea

urchins have a high concentration of mycosporine amino acids that protect them from UV damage. Mycosporine amino

acids are obtained through the diet of the adult and are stored in the egg. However, there is fear that the amphibians are

declining because of the increased UV-B reaching the earth's surface. UV-A and UV-B reach the earth's surface. UV-B is

increasingly hitting the earth's surface because of the depleting ozone layer. One of the more common effects of UV-B is

adjacent thymidines condensing into cyclobutane pyrimidine dimers (CBPDs) which impede DNA replication and

transcription. UV-C (200-280nm) is the most harmful type of UV to organisms, however, due to oxygen in the atmosphere