Jose M Martin Duran: The symbiosis of Osedax worms and the genomic adaptation to digest vertebrate bones

Abstract:

Bacterial symbioses allow annelids to colonise extreme ecological niches, such ashydrothermal vents and whale falls. Yet, the genetic principles sustaining thesesymbioses remain unclear. Here, we show that different genomic adaptations underpinthe symbioses of phylogenetically related annelids with distinct nutritional strategies.Genome compaction and extensive gene losses distinguish the heterotrophicsymbiosis of the bone-eating wormOsedax frankpressi from the chemoautotrophicsymbiosis of deep-sea Vestimentifera.Osedax’s endosymbionts complement many ofthe host's metabolic deficiencies, including the loss of pathways to recycle nitrogenand synthesise some amino acids.Osedax’s endosymbionts possess the glyoxylatecycle, which could allow more efficient catabolism of bone-derived nutrients and theproduction of carbohydrates from fatty acids. Unlike in most Vestimentifera, innateimmunity genes are reduced inO. frankpressi, which, however, has an expansion ofmatrix metalloproteases to digest collagen. Our study supports that distinct nutritionalinteractions influence host genome evolution differently in highly specialisedsymbioses.