title: Breakdown of coral colonial form under reduced pH conditions is initiated in polyps and mediated through apoptosis.
abstract: Certain stony corals can alternate between a calcifying colonial form and noncalcifying solitary polyps, supporting the hypothesis that corals have survived through geologic timescale periods of unfavorable calcification conditions. However, the mechanisms enabling this biological plasticity are yet to be identified. Here we show that incubation of two coral species (Pocillopora damicornis and Oculina patagonica) under reduced pH conditions (pH 7.2) simulating past ocean acidification induce tissue-specific apoptosis that leads to the dissociation of polyps from coenosarcs. This in turn leads to the breakdown of the coenosarc and, as a consequence, to loss of coloniality. Our data show that apoptosis is initiated in the polyps and that once dissociation between polyp and coenosarc terminates, apoptosis subsides. After reexposure of the resulting solitary polyps to normal pH (pH 8.2), both coral species regenerated coenosarc tissues and resumed calcification. These results indicate that regulation of coloniality is under the control of the polyp, the basic modular unit of the colony. A mechanistic explanation for several key evolutionarily important phenomena that occurred throughout coral evolution is proposed, including mechanisms that permitted species to survive the third tier of mass extinctions.
authors: Marine Biology Department, Leon H. Charney School of Marine Sciences, University of Haifa, Mount Carmel, Haifa 31905, Israel; Interuniversity Institute for Marine Science, Eilat 88103, Israel; Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat 88112, Israel;
authors: Hagit
authors: H
authors: Kvitt
authors: Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University, Beer-Sheva 8410501, Israel; and.
authors: Esti
authors: E
authors: Kramarsky-Winter
authors: The Mina & Everard Goodman Faculty for Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel.
authors: Keren
authors: K
authors: Maor-Landaw
authors: Interuniversity Institute for Marine Science, Eilat 88103, Israel;
authors: Keren
authors: K
authors: Zandbank
authors: Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University, Beer-Sheva 8410501, Israel; and.
authors: Ariel
authors: A
authors: Kushmaro
authors: Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat 88112, Israel;
authors: Hanna
authors: H
authors: Rosenfeld
authors: Interuniversity Institute for Marine Science, Eilat 88103, Israel; The Mina & Everard Goodman Faculty for Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel.
authors: Maoz
authors: M
authors: Fine
authors: Marine Biology Department, Leon H. Charney School of Marine Sciences, University of Haifa, Mount Carmel, Haifa 31905, Israel; Interuniversity Institute for Marine Science, Eilat 88103, Israel; dtchernov@univ.haifa.ac.il.
authors: Dan
authors: D
authors: Tchernov
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000166:cytology / Q000648:ultrastructure; D017209:Apoptosis; D006863:Hydrogen-Ion Concentration; D046529:Microscopy, Electron, Transmission
keywords: apoptosis; corals; ocean acidification
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