Speaker
Description
In animal-microbe interactions, symbiont lifestyles in the host can range from intimate intracellular environments to looser extracellular associations. For each of these lifestyles, symbiont acquisition and maintenance will likely require specific sets of adaptations and interactions between both partners. Deep-sea mussels harbor their symbiotic bacteria in or on specialized gill cells called bacteriocytes with three different morphologies: as endosymbionts engulfed intracellularly in vacuoles, as ectosymbionts in crypts on the outside of host bacteriocytes, or as extracellular endosymbionts. In the latter, the symbionts sit inside bacteriocytes but extracellularly in a complex, interconnected channel system with pores that are open to the environment. The factors driving these different lifestyles and the specific roles of host and symbiont remain unidentified. Our research aims to identify the molecular and cellular determinants involved in the remodeling of the bacteriocytes to better understand each partner's role. By comparing functional capabilities of different symbionts and their free-living relatives, we identified several genes exclusive to the extracellular endosymbionts. Comparing hosts with different symbiont lifestyles, we discovered expanded functions linked to cytoskeleton proteins in mussels with extracellular endosymbionts. Upcoming imaging analyses aim to visualize these candidate factors in situ, comparing symbiotic mussels and cell types to their non-symbiotic counterparts.
