Meeting Abstract
Corals, which are members of Phylum Cnidaria, play a critical role in coral reefs, one of the world’s most productive and diverse ecosystems. Coral reef health depends on a mutualistic symbiotic relationship between cnidarians and photosynthetic dinoflagellates of the family Symbiodiniaceae. However, a variety of stressors to reefs such as elevated temperatures and coral disease contribute to breakdown of this symbiotic relationship which can lead to coral death and collapse of the reef ecosystem. To better understand coral disease and symbiosis, we looked at a group of potential immune proteins in cnidarians called GTPases of immunity associated proteins (GIMAPs). In vertebrates these proteins regulate the fate of developing lymphocytes and a previous study revealed their presence and potential immune function in cnidarians. To better understand the evolution of GIMAPs within this phylum, bioinformatic searches were conducted in a diversity of publicly available genomes and transcriptomes. Additionally, to better understand the role of GIMAPs in cnidarian immunity and symbiosis, both symbiotic and aposymbiotic Exaiptasia pallida were exposed to the immune stimulant lipopolysaccharide (LPS) and gene expression of four GIMAP-like sequences called Ep_GIMAPs was measured using qPCR. The bioinformatic searches revealed two types of GIMAP-like sequences termed long and short, with patchy distribution, including cnidarians that contain one, both, or neither GIMAP type. The gene expression work showed two of the Ep_GIMAPs had greater expression in symbiotic than aposymbiotic E. pallida, implying a function in regulating symbiosis. However, Ep_GIMAPs did not show significant expression differences in response to LPS treatment, suggesting a role other than immunity. Overall, this work provides a greater understanding of the cnidarian immune system and the evolution of GIMAPs.
