Community Research and Development Information Service - CORDIS

Periodic Report Summary 1 - ESYMBIOSIS (Molecular Basis of Coral Symbiosis)

Mutualistic symbioses are key to evolutionary and ecological novelties. Eukaryotic cells evolved through the acquisition of bacteria, and coral reef ecosystems depend on the endosymbiosis between corals and photosynthetic dinoflagellates. Most corals produce non-symbiotic larvae that acquire symbionts via phagocytosis into host endodermal cells. After acquisition, symbionts reside inside specialized phagosomes (“symbiosomes”) in the endodermal cells and transfer fixed carbon to their coral hosts to support their nutrition and thus survival in nutrient poor environments. Many questions about the molecular mechanisms underlying symbiosis establishment and maintenance remain unresolved, mostly due to the lack of a tractable model system. The goal of the project was to use Aiptasia, a marine sea anemone that lives in a stable symbiosis with the same symbionts as corals as a model system for elucidating key aspects of the molecular basis of symbiosis. To achieve this goal, I proposed to (1) analyze the cellular mechanisms and the effects of elevated temperature on initial symbiont acquisition in Aiptasia larvae; (2) identify conserved genes involved in symbiont acquisition and maintenance in cnidarian larvae by RNASeq, and (3) describe Aiptasia larval development and establish transgenesis using microinjection.

To date, my lab has developed a robust protocol to induce Aiptasia spawning in the lab, analyzed embryonic and larval development in relation to symbiont phagocytosis, and completed the first comparison of symbiosis specificity between Aiptasia and corals. We participated in sequencing the Aiptasia genome and identified a first set of candidate genes involved in symbiosis establishment by RNA-Seq. We have developed molecular tools such as in situ hybridization, confocal microscopy, protein extraction and metabolomics assays and are now investigating identified molecular key-players using such cell biological tools.

Coral reef ecosystems are ecologically and economically immensely important, but greatly threatened by global climate change. Accordingly, the investigation of the molecular basis of cnidarian endosymbiosis is a highly relevant and timely topic. I envision that my lab will make important contributions in unraveling fundamental aspects of coral symbiosis, a phenomenon that has shaped many evolutionary innovations and continues to allow adaptation to ecological niches. More information can be found at:

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Life Sciences
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