Marine Tubeworm Metamorphosis Induced by Arrays of Bacterial Phage Tail–Like Structures

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Science  31 Jan 2014:
Vol. 343, Issue 6170, pp. 529-533
DOI: 10.1126/science.1246794

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Big MACs

Tubeworms are important marine benthic species that encrust rocks and contribute to fouling of man-made objects, such as ships' hulls and drilling well heads. Like most marine invertebrates, the larval stages of tubeworms are free-swimming, but the cues for larval settlement and the triggers for metamorphosis are mysterious. Shikuma et al. (p. 529, published online 9 January) experimented on larval settlement by the tubeworm, Hydroides elegans, which needs to associate with a biofilm-forming bacterium, Pseudoalteromonas luteoviolacea, before settlement can occur. The bacterium was found to express metamorphosis-associated contractile structures (MACs) in large and structurally elaborate arrays that allow the tubeworm larvae to develop.


Many benthic marine animal populations are established and maintained by free-swimming larvae that recognize cues from surface-bound bacteria to settle and metamorphose. Larvae of the tubeworm Hydroides elegans, an important biofouling agent, require contact with surface-bound bacteria to undergo metamorphosis; however, the mechanisms that underpin this microbially mediated developmental transition have been enigmatic. Here, we show that a marine bacterium, Pseudoalteromonas luteoviolacea, produces arrays of phage tail–like structures that trigger metamorphosis of H. elegans. These arrays comprise about 100 contractile structures with outward-facing baseplates, linked by tail fibers and a dynamic hexagonal net. Not only do these arrays suggest a novel form of bacterium-animal interaction, they provide an entry point to understanding how marine biofilms can trigger animal development.

  • * These authors contributed equally to this work.

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