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Georgia Journal of Science

Article Title

THE ROLE OF SPHINGOSINE RHEOSTAT IN UPTAKE OF DINOFLAGELLATE SYMBIONTS BY THE SEA ANEMONE EXAIPTASIA PALLIDA

Abstract

In phylum Cnidaria, animals such as corals and sea anemones engage in a mutualistic symbiotic relationship with photosynthetic dinoflagellates. These dinoflagellates play a critical role in nutrient production and coral livelihood. Recently, there has been a rising public awareness of coral bleaching and its negative impact on the reef ecosystem. Coral bleaching is when a stressor, such as increased water temperature, induces loss of symbionts which can lead to pathogen susceptibility, nutrient deficiency, and an overall vulnerability of the organism. Therefore, it is useful to investigate closely related lab models such as Exaiptasia pallida, a species of sea anemone, to gain a better understanding of this host-symbiont relationship. This research explores the role the sphingosine rheostat plays in the symbiotic partnership of dinoflagellates and E. pallida. The sphingosine rheostat is a regulatory pathway that includes the sphingolipids, sphingosine (Sph) and sphingosine 1-phosphate (S1P), along with the modifying enzymes sphingosine kinase and sphingosine 1-phosphate phosphatase. An abundance of S1P signals for cell proliferation and survival, while Sph promotes apoptosis. Previous research suggests that the sphingosine rheostat plays a role in the establishment, maintenance, and breakdown of symbiosis. However, the impact of individual rheostat components on symbiont colonization is still poorly understood and warrants further investigation. Therefore, this research used exposures to a sphingosine kinase inhibitor and FTY720, a S1P receptor agonist,​ and measured their impact on the uptake of dinoflagellates at the onset of symbiosis. The sphingosine kinase inhibitor decreased dinoflagellate uptake by E. pallida (p=0.042), while the results for FTY720 currently suggest no impact on uptake and that high concentrations structurally compromised the organism. Overall these results demonstrate the importance of sphingosine kinase in successful symbiosis establishment.

Acknowledgements

Berry College Department of Biology

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