title: Cell proliferation and migration during early development of a symbiotic scleractinian coral.
abstract: 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-labelled 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-labelled cells was tracked during a 3-day chase. The pharynx and gastrodermis were identified as the most proliferative tissues in the developing polyp, and BrdU-labelled 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 recorded in the calicodermis at all stages, despite active, ongoing skeletal deposition. In dinoflagellate symbionts, DNA synthesis was systematically higher than coral host gastrodermis, especially in planula and early metamorphosis. The symbiont to host cell ratio remained constant, however, indicating successive post-mitotic control mechanisms by the host of its dinoflagellate density in early life stages, increasingly shifting to apoptosis in the growing primary polyp.
authors.affiliation: Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland Unité MCAM UMR7245, Sorbonne Universités, Museum National d'Histoire Naturelle (MNHN), CNRS, Paris, France.
authors.forename: Agathe
authors.initials: A
authors.lastname: Lecointe
authors.affiliation: Unité MCAM UMR7245, Sorbonne Universités, Museum National d'Histoire Naturelle (MNHN), CNRS, Paris, France icoulon@mnhn.fr.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Domart-Coulon
authors.affiliation: Unité MCAM UMR7245, Sorbonne Universités, Museum National d'Histoire Naturelle (MNHN), CNRS, Paris, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Paris
authors.affiliation: Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland.
authors.forename: Anders
authors.initials: A
authors.lastname: Meibom
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D002465:Cell Movement; D049109:Cell Proliferation; D004141:Dinoflagellida / Q000502:physiology*; D013559:Symbiosis
keywords: BrdU; apoptosis; cell proliferation; dinoflagellates; metamorphosis; scleractinia