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Talk by Harald Gruber-Vodicka

Title: "Physiology and evolution of intracellular symbioses in marine invertebrates"
Occasion: SFB Seminar
Host: Achim Paululat
Start: 08.12.2022 - 16:15
Location: CellNanOs 38/201

About the speaker: Dr. Harald Gruber-Vodicka researches at the Max-Planck-Institute for Marine Microbiology in Bremen.

Abstract of the talk: Intracellular symbiosis is a key source for evolutionary innovation and, with the mitochondria and plastids, stands at the basis of all macroscopic life. Mitochondria share their ancestry with Alphaproteobacteria, a group of bacteria where many are well adapted to live within host cells. Members of the Alphaproteobacteria have repeatedly associated with ever more complex hosts and today fulfill many important roles, e.g. supplying nitrogen to plants or providing essential amino acids to insects that feed on nutrient poor plant sap.

In this talk I present the striking innovations that intracellular Alphaproteobacteria bacteria deliver to two enigmatic animal groups - placozoans and Paracatenula flatworms. Present in all temperate to tropical oceans, the two host groups have very simple body plans and are readily cultivable in the lab. Using an interdisciplinary approach, we show that these hosts have very different benefits and roles when interacting with their intracellular symbionts. The mouthless Paracatenula flatworms are highly integrated with their chemosynthetic Riegeria symbionts and the host completely relies on its symbionts for nutrition and energy storage. In contrast to this, the placozoans largely cater to their Grellia symbionts and in return receive a selected set of vitamins and co-factors. I am excited to share our latest results that suggest that the Grellia endosymbionts also supplies digestive enzymes to their placozoan hosts that massively expand their hosts’ access to important and ubiquitously available food sources. Building on these insights, I will provide my vision for symbiosis research and illustrate how pivotal it is to address and understand intracellular associations that can massively alter physiology, ecology and gene flow of animal hosts.