Attenuation of host NO production by MAMPs potentiates development of the host in the squid-vibrio symbiosis

Cell Microbiol. 2011 Apr;13(4):527-37. doi: 10.1111/j.1462-5822.2010.01552.x.


Bacterial pathogens typically upregulate the host's production of nitric oxide synthase (NOS) and nitric oxide (NO) as antimicrobial agents, a response that is often mediated by microbe-associated molecular patterns (MAMPs) of the pathogen. In contrast, previous studies of the beneficial Euprymna scolopes/Vibrio fischeri symbiosis demonstrated that symbiont colonization results in attenuation of host NOS/NO, which occurs in high levels in hatchling light organs. Here, we sought to determine whether V. fischeri MAMPs, specifically lipopolysaccharide (LPS) and the peptidoglycan derivative tracheal cytotoxin (TCT), attenuate NOS/NO, and whether this activity mediates the MAMPs-induced light organ morphogenesis. Using confocal microscopy, we characterized levels of NOS with immunocytochemistry and NO with a NO-specific fluorochrome. When added exogenously to seawater containing hatchling animals, V. fischeri LPS and TCT together, but not individually, induced normal NOS/NO attenuation. Further, V. fischeri mutants defective in TCT release did not. Experiments with NOS inhibitors and NO donors provided evidence that NO mediates apoptosis and morphogenesis associated with symbiont colonization. Attenuation of NOS/NO by LPS and TCT in the squid-vibrio symbiosis provides another example of how the host's response to MAMPs depends on the context. These data also provide a mechanism by which symbiont MAMPs regulate host development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aliivibrio fischeri / physiology*
  • Animals
  • Decapodiformes / anatomy & histology
  • Decapodiformes / metabolism
  • Decapodiformes / microbiology*
  • Host-Pathogen Interactions*
  • Light
  • Morphogenesis
  • Nitric Oxide / metabolism*
  • Nitric Oxide Donors / metabolism
  • Nitric Oxide Synthase / metabolism
  • Symbiosis / physiology*


  • Nitric Oxide Donors
  • Nitric Oxide
  • Nitric Oxide Synthase