Cell proliferation and migration during early development of a symbiotic scleractinian coral

In scleractinian reef-building corals, patterns of cell self-renewal, migration and death remain virtually unknown, limiting our understanding of cellular mechanisms underlying initiation of calcification, and ontogenesis of the endosymbiotic dinoflagellate relationship. In this study we pulse-labeled the coral Stylophora pistillata for 24 h with BrdU at four life stages (planula, early metamorphosis, primary polyp, and adult colony) to investigate coral and endosymbiont cell proliferation during development, while simultaneously recording TUNEL-positive, i.e. apoptotic, nuclei. In the primary polyp, the fate of BrdU-labeled cells was tracked during a 3 days chase. The pharynx and gastrodermis were identified as the most proliferative tissues in the developing polyp, and BrdU-labeled cells accumulated in the surface pseudostratified epithelium and the skeletogenic calicodermis during the chase, revealing cell migration to these epithelia. Surprisingly, the lowest cell turnover was recor...