Exploring the Role of Glutamate Signaling in the Regulation of the Aiptasia-Symbiodiniaceae Symbiosis

  • Migle Konciute

Student thesis: Master's Thesis

Abstract

The symbiotic relationship between cnidarians and their photosynthetic dinoflagellate symbionts underpins the success of coral reef communities in oligotrophic, tropical seas. Despite several decades of study, the cellular and molecular mechanisms that regulate the symbiotic relationship between the dinoflagellate algae and the coral hosts are still not clear. One of the hypotheses on the metabolic interactions between the host and the symbiont suggests that ammonium assimilation by the host can be the underlying mechanism of this endosymbiosis regulation. An essential intermediate of the ammonium assimilation pathway is glutamate, which is also known for its glutamatergic signaling function. Interestingly, recent transcriptomic level and DNA methylation studies on sea anemone Aiptasia showed differences in metabotropic glutamate signaling components when comparing symbiotic and non-symbiotic animals. The changes in this process on transcriptional and epigenetic levels indicate the importance of glutamate signaling in regard to cnidarian symbiosis. In this study, I tested glutamatergic signaling effect on symbiosis in sea anemone Aiptasia using a broad-spectrum glutamate receptor inhibitor 7- CKA and glutamate. Significantly decreased cell density was observed in animals with inhibitor treatment suggesting a possible correlation between glutamate signaling and the establishment or maintenance of symbiosis. Using RNA-Seq, I was able to obtain transcriptional profiles of the animals under inhibitor and glutamate treatment. Differential gene expression and gene ontology analyses indicated changes in amino acid metabolism, lipid metabolism and such signaling pathways as MAPK, NF-kappa B and phospholipase C. Although amino acid and lipid metabolism could be a result of the reduced symbiotic state of inhibitor treated Aiptasia, the signaling pathways which are related to apoptosis and immune response provide an exciting venue for direct regulatory interaction between symbiosis and glutamatergic signaling. However, as these signaling pathways mainly act via signal transduction through protein phosphorylation, further studies looking at changes on a post-translational level might provide further insight into the mechanisms underlying the observed phenotype.
Date of AwardApr 2020
Original languageEnglish (US)
Awarding Institution
  • Biological, Environmental Science and Engineering
SupervisorManuel Aranda (Supervisor)

Keywords

  • Aiptasia
  • symbiosis
  • glutamate
  • signaling
  • RNA-Seq

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