Division of Microbial Ecology, Department of Microbiology and Ecosystem Science
Centre for Microbiology and Environmental Systems Science, University of Vienna
Abstract
Symbioses between animals and microbes are widespread and have significant impacts on host physiology, ecosystem function, and evolution. In particular, symbiosis with photosynthetic algae (“photosymbiosis”), like that between corals and the cosmopolitan Symbiodiniaceae dinoflagellates, allows hosts to dominate nutrient-poor tropical waters worldwide. In the talk, I will first discuss recent work investigating the mechanisms of sterol nutrient transfer in coral-algal symbiosis. Sterols are essential for their sterol-auxotrophic host cnidarians, yet types and mechanisms of sterol transfer were hitherto unknown. Using a combination of phylogenetics, lipidomics, gas chromatography-mass spectrometry, immunofluorescence, pharmacology, and quantitative PCR in corals and the model sea anemone Aiptasia, we observed surprising plasticity of sterol use by the host, and our data indicate that sterol transfer is mediated by symbiosis-specific, non-canonical NPC2 proteins that are adapted to the particular cellular environment.
In addition to corals, Symbiodiniaceae algae associate with other diverse, ecologically important marine invertebrates including flatworms, sponges, and mollusks. I will therefore discuss my current and future work using these photosymbioses to ask: how do these very different host organisms interact on the cellular level with the same intracellular algal symbiont? What are the molecular mechanisms underlying these symbioses, particularly complex metabolic exchange? To address this, we are combining functional experimentation in old and new model systems, single-cell transcriptomics, metabolomics/lipidomics, and MALDI-MS metabolic imaging. Overall the aim of our work is to understand globally widespread and evolutionarily important photosymbioses and their response to environmental change.
Bio Sketch
Dr. Elizabeth Hambleton is a Group Leader in the Division of Microbial Ecology (DOME) within the Centre for Microbiology and Environmental Systems Science (CMESS) at the University of Vienna. Hambleton received her PhD from Stanford University, where her work was supported by an NSF Graduate Research Fellowship, and conducted her postdoctoral work in the Centre for Organismal Studies at the University of Heidelberg. Throughout her career, Hambleton has been an expert in developing the sea anemone Aiptasia as a laboratory model to investigate the molecular mechanisms of coral-algal symbiosis. Since its establishment in September 2020, her group is studying the evolution and molecular mechanisms of diverse, ecologically important animal-algal ‘photosymbioses’ using a combination of single-cell transcriptomics, metabolomics, mass-spectrometry imaging, and functional manipulation in established and new model systems.
