How coral cures your ills

Next time you successfully fight off a nasty infection, give thanks to the Great Barrier Reef. A dramatic discovery by an Australian team of scientists has revealed that the ability of humans to resist bacterial diseases may go as far back in our ancestry as corals.

Researchers at the ARC Centre of Excellence for Coral Reef Studies (CoECRS) have found three genes in Acropora (staghorn) corals which show a very fast, strong immune response to the presence of bacteria – and the same genes also occur in mammals, including people.

"It's early days, but it certainly looks as if key aspects of our ability to resist bacteria are extremely ancient and may have been pioneered by the ancestor of corals – and then passed down to humans in our evolutionary lineage," explains team leader Professor David Miller of CoECRS and James Cook University.

"Corals are constantly attacked by bacteria in their natural environment, and so have perfected very efficient defences against them," he says. "These defences apparently work well enough to be preserved in mammals like us, and possibly in plants too. Certain animals in between us and coral, like roundworms and flies, seem to have lost these genes, but our line appears to have retained them."

The genes belong to a family known as the GiMAPs and have been associated with anti-bacterial immunity in mammals, including humans. The team made its discovery by challenging living colonies of Acropora with certain chemicals commonly found in the coats of bacteria, and studying which genes reacted across virtually its entire genome of 20,000-plus genes. "We were quite surprised at how rapidly and strongly these three genes in particular reacted to the presence of bacterial proteins," Prof. Miller says. "It was spectacular."