Abstract
BackgroundCnidarian – dinoflagellate intracellular symbioses are one of the most important mutualisms in the marine environment. They form the trophic and structural foundation of coral reef ecosystems, and have played a key role in the evolutionary radiation and biodiversity of cnidarian species. Despite the prevalence of these symbioses, we still know very little about the molecular modulators that initiate, regulate, and maintain the interaction between these two different biological entities. In this study, we conducted a comparative host anemone transcriptome analysis using a cDNA microarray platform to identify genes involved in cnidarian – algal symbiosis.ResultsWe detected statistically significant differences in host gene expression profiles between sea anemones (Anthopleura elegantissima) in a symbiotic and non-symbiotic state. The group of genes, whose expression is altered, is diverse, suggesting that the molecular regulation of the symbiosis is governed by changes in multiple cellular processes. In the context of cnidarian – dinoflagellate symbioses, we discuss pivotal host gene expression changes involved in lipid metabolism, cell adhesion, cell proliferation, apoptosis, and oxidative stress.ConclusionOur data do not support the existence of symbiosis-specific genes involved in controlling and regulating the symbiosis. Instead, it appears that the symbiosis is maintained by altering expression of existing genes involved in vital cellular processes. Specifically, the finding of key genes involved in cell cycle progression and apoptosis have led us to hypothesize that a suppression of apoptosis, together with a deregulation of the host cell cycle, create a platform that might be necessary for symbiont and/or symbiont-containing host cell survival. This first comprehensive molecular examination of the cnidarian – dinoflagellate associations provides critical insights into the maintenance and regulation of the symbiosis.
Highlights
Cnidarian – dinoflagellate intracellular symbioses are one of the most important mutualisms in the marine environment
Since 104 false positives were expected from the 10,368 gene-tests performed under the null hypothesis when P = 0.01, we applied a False Discovery Rate (FDR) multiple-testing adjustment to control for type I error [17]
We demonstrate that the gene expression profile of the host sea anemone Anthopleura elegantissima changes in symbiosis with the dinoflagellate Symbiodinium muscatinei
Summary
Cnidarian – dinoflagellate intracellular symbioses are one of the most important mutualisms in the marine environment They form the trophic and structural foundation of coral reef ecosystems, and have played a key role in the evolutionary radiation and biodiversity of cnidarian species. Mutualistic symbioses are defined as the association between unrelated organisms living together in a close, protracted relationship that benefits both partners. They are common in nature and are a driving force in evolution [1]. Cnidarian – dinoflagellate associations represent one of the most important symbioses in the marine environment These partnerships form the trophic and structural foundation of coral reef ecosystems, and have played a (page number not for citation purposes). The mechanisms of avoiding host digestion remain largely unknown, some studies suggest that persistence may be due to the failure of phagosomelysosome fusion [3-6]
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