How does an animal behave like a plant? Physiological and molecular adaptations of zooxanthellae and their hosts to symbiosis - 10/04/18
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Abstract |
Cnidarians (corals and sea anemones) harbouring photosynthetic microalgae derive several benefits from their association. To allow this association, numerous symbiotic-dependent adaptations in both partners, resulting from evolutionary pressures, have been selected. The dinoflagellate symbionts (zooxanthellae) are located inside a vesicle in the cnidarian host cell and are therefore exposed to a very different environment compared to the free-living state of these microalgae in terms of ion concentration and carbon content and speciation. In addition, this intracellular localization imposes that they rely completely upon the host for their nutrient supply (nitrogen, CO2). Symbiotic-dependent adaptations imposed to the animal host by phototrophic symbiosis are more relevant to photosynthetic organisms than to metazoans: indeed, the cnidarian host often harbours diurnal changes of morphology to adapt itself to the amount of light and possesses carbon-concentrating mechanisms, antioxidative defences and UV sunscreens similar to that present in phototrophs. These adaptations and the contrasting fragility of the association are discussed from both ecological and evolutionary points of view.
Le texte complet de cet article est disponible en PDF.Keywords : Cnidarians, Corals, Symbiosis, Dinoflagellate, Holobiont, Adaptation, Coral bleaching, MAA: Carbon-concentrating Mechanism, Superoxide dismutase, Evolution
Plan
☆ | This article is a follow up of the colloquium Symbiosis and cohabitation, held at the “Institut de France”, Paris, on 25 April 2017. |
☆☆ | Cet article fait suite au colloque Symbiose et cohabitation, qui s’est tenu à l’Institut de France, à Paris, le 25 avril 2017. |
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