Bacterial pathogen on the hunt for stressed corals

Coral reefs are threatened by disease. Using microfluidics and video microscopy to spy on the behavior of a coral pathogen, we discovered that it follows gradients of chemical cues leaking from the coral surface and responds more strongly to those coming from heat-stressed hosts.

HFSP Young Investigator Grant holders Roman Stocker and Justin Seymour and colleagues
authored on Fri, 07 February 2014

Tropical reef-building corals are complex biological systems comprised of a delicate balance of partnerships (symbioses) among the coral animals and the microbes that live with them, including single-celled algae, bacteria, and viruses. We used microfluidics and video microscopy to spy on the interactions among these diverse partners and to learn how pathogens manage to invade such a rich ecosystem. We discovered that the pathogen follows gradients of chemical cues, in particular dimethylsulfoniopropionate (DMSP), leaking from the coral surface – a driving signal originally produced by the algae inside the coral – to reach its host. These pathogens have a wide variety of behaviors, including chemotaxis (the ability to navigate based on chemical gradients) and chemokinesis (the ability to increase swimming speeds in the presence of a chemical cue) that help them follow this chemical trail in the complex ocean microenvironment and successfully infect their hosts. Field experiments on Australia’s Great Barrier Reef revealed that warming waters, for example associated with global change, increase the amount of chemical signal (DMSP) coming from the coral and simultaneously increase the rate and intensity at which the pathogen homes in on the coral surface. Thus, these pathogen attacks are predicted to become more intense as ocean waters become warmer in the future.

Text by Melissa Garren and Roman Stocker

Figure 4 from ISME Journal, 2013 Dec 12, Garren et al., A bacterial pathogen uses dimethylsulfoniopropionate as a cue to target heat-stressed corals. Image by Melissa Garren, Glynn Gorick and Roman Stocker.

Reference

A bacterial pathogen uses dimethylsulfoniopropionate as a cue to target heat-stressed corals. Garren M, Son K, Raina JB, Rusconi R, Menolascina F, Shapiro OH, Tout J, Bourne DG, Seymour JR, Stocker R. ISME J. 2013 Dec 12. doi: 10.1038/ismej.2013.210. 

Pubmed link

Press release from MIT