title: Potent cytotoxins produced by a microbial symbiont protect host larvae from predation.
abstract: Larvae of the sessile marine invertebrate Bugula neritina (Bryozoa) are protected by an effective chemical defense. From the larvae, we isolated three bryostatin-class macrocyclic polyketides, including the novel bryostatin 20, that deterred feeding by a common planktivorous fish that co-occurs with B. neritina. A unique bacterial symbiont of B. neritina, Endobugula sertula, was hypothesized as the putative source of the bryostatins. We show that: (1) bryostatins are concentrated in B. neritina larvae and protect them against predation by fish; (2) the adults are not defended by bryostatins; and (3) E. sertula produces bryostatins. This study represents the first example from the marine environment of a microbial symbiont producing an anti-predator defense for its host and, in this case, specifically for the host's larval stage, which is exceptionally vulnerable to predators.
authors.affiliation: Graduate College of Marine Studies, University of Delaware, Lewes, DE 19958, USA. nlopanik@umich.edu
authors.forename: Nicole
authors.initials: N
authors.lastname: Lopanik
authors.forename: Niels
authors.initials: N
authors.lastname: Lindquist
authors.forename: Nancy
authors.initials: N
authors.lastname: Targett
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D054713:Bryostatins; D002013:Bryozoa / Q000254:growth & development* / Q000502:physiology*; D004777:Environment; D005247:Feeding Behavior; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D007814:Larva / Q000502:physiology; D018942:Macrolides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D020560:Proteobacteria / Q000737:chemistry* / Q000502:physiology; D013559:Symbiosis
chemical_list: D054713:Bryostatins; D007783:Lactones; D018942:Macrolides; C487869:bryostatin 20