VEGA, Rebecca/L; EPEL, David: Early Embryonic Programmed Cell Death in the Sea Urchin, Strongylocentrotus purpuratus: Developmental Timing, Control, and Responses to Environmental Disturbance

Marine larva are exposed to a variety of biotic and abiotic stresses during development. Variations in water and light conditions, predator and prey abundance, as well as exposure to xenotoxins may all contribute to the disruption of embryogenesis. Aquatic organisms have adapted several mechanisms to defend themselves against potentially damaging environmental perturbations. Apoptosis, the main form of programmed cell death in metazoans, is essential for the destruction of damaged or abnormal cells in embryogenesis. Our studies on the sea urchin, Strongylocentrotus purpuratus, have identified a small number of embryos that display apoptotic-like characteristics during the very first hours of development and continuing on past gastrulation. This is in contrast to other lower vertebrate model systems studied thus far, in which apoptosis can only occur at a predetermined time in development. We are currently investigating whether our preliminary findings do in fact constitute bona fide apoptosis. We hope to determine the timing at which urchins do undergo apoptosis naturally and when they gain the capability to induce apoptosis in response to cellular damage.