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		The Effects of Ultraviolet Light on the Fertilization and Development of the Sea Urchin Embryo Jill K. Flemming, Franklin & Marshall College, Class of 2001 Introduction The objective of this project is to observe the effects of UV radiation on both fertilization and development in the sea urchin embryo. Ultraviolet (UV) light is becoming an increasing concern in today's society. Humans, as well as other organisms, are being exposed to more and more UV rays due to the expanding hole in and thinning of Earth's ozone layer. One way to examine the specific effects of the UV light on living organisms is to study the sea urchin. The embryo of the sea urchin is transparent, so it makes viewing development easier than most other organisms. The sea urchin spawns and develops in shallow tide pools. Therefore, the effect of UV light is a concern for fertilization and embryonic development of the sea urchin embryos. Previous experiments have shown that at a depth of one meter (which is the approximate depth of most tide pools) only 20% of UV radiation has been filtered out by the water, leaving 80% of the harmful rays to affect the urchin embryos. UV light disrupts microtubule and cytoskeleton development, as well as cleavage and gastrulation. Therefore, we expect to see the irradiated embryos dividing unevenly, cells cleaving improperly (partially or not at all), and gastrulation probably not occurring at all.