wes_von_papineäu
Our Roving Correspondent
NEW SCIENTIST (London, UK) 11 March 08 Toxic newts lose war against 'super-immune' snakes (Phil McKenna)
An ancient battle between snakes and their prey could be over – with the snake victorious. The outcome could have ominous implications for the battles playing out between humans and the microbes that infect us.
Garter snakes along the west coast of North America have evolved "super-immunity" against a newt armed with a poison so deadly that a single animal can kill a dozen people. The poison has escalated in power as the snake – the newt's main predator – has evolved resistance.
Charles Hanifin of Stanford University, California, US, and colleagues measured the toxicity of 383 rough-skinned newts (newts of the genus Taricha) at 28 sites from British Columbia to central California.
The newts carry extremely high levels of tetrodotoxin (TTX) – the same deadly poison found in blowfish.
"Ounce for ounce, some of these populations are the most toxic amphibians on the planet," Hanifin says.
'Untouchable' snakes
They compared this toxin data to the resistance found in common garter snakes (Thamnophis sirtalis) throughout the region.
In most locations, the snakes' level of resistance closely matched newt toxicity. In such cases, the poison temporarily slows the snakes down but isn't enough to kill them. This supports "arms race" theories explaining how toxicity and resistance co-evolve.
But in some areas where newt toxicity was relatively high, the poison had no measurable affect on snake mobility.
The team found that resistant snakes had a single genetic mutation on TTX receptor sites on their neural and muscle cells, which prevented the toxin from binding. It made snakes with this mutation "untouchable".
"It is pretty much biologically impossible for the newts to ever catch up," Hanifin says.
While the snakes achieved this super-immunity from a single mutation, Hanifin says that increases in toxicity only occur in smaller incremental changes in a number of genes. And Hanifin thinks microbes infecting humans could also develop super-immunity.
"The rapid evolution of resistance in snakes doesn't bode all that well [for humans]," Hanifin says. "When you have relatively simple toxins or simple drugs you can get this rapid, extreme resistance – and it doesn't take that long to happen."
However, Craig Benkman of the University of Wyoming cautions against extrapolating from snakes and newts to antibiotics and microbes.
"It might apply to these examples that they are alluding to, but it may not," he says, noting that there is great variation in the molecular pathways and number of genes controlling chemical receptors on microbes.
"If there are a lot of genes with small affect than this analogy won't apply," Benkman adds.
Journal Reference: PLoS Biol (DOI: 10.1371/journal.pbio.0060060)
http://www.newscientist.com/article/dn13438-toxic-newts-lose-war-against-superimmune-snakes.html
THE TIMES (London, UK) 11 March 08 Snake evolves to take on toxic newt (Mark Henderson)
http://www.timesonline.co.uk/tol/news/environment/article3525429.ece
SAN FRANCISCO CHRONICLE (California) 11 March 08 Garter snakes out-evolve food prey – newts (David Perlman)
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/03/11/BAV0VEVRN.DTL
VANCOUVER SUN (British Columbia) 11 March 08 Evolution can make sudden leaps: scientists (Maggie Fox)
http://www.canada.com/vancouversun/news/story.html?id=c593fc4b-790d-4163-9ced-9d33b2a3985a
An ancient battle between snakes and their prey could be over – with the snake victorious. The outcome could have ominous implications for the battles playing out between humans and the microbes that infect us.
Garter snakes along the west coast of North America have evolved "super-immunity" against a newt armed with a poison so deadly that a single animal can kill a dozen people. The poison has escalated in power as the snake – the newt's main predator – has evolved resistance.
Charles Hanifin of Stanford University, California, US, and colleagues measured the toxicity of 383 rough-skinned newts (newts of the genus Taricha) at 28 sites from British Columbia to central California.
The newts carry extremely high levels of tetrodotoxin (TTX) – the same deadly poison found in blowfish.
"Ounce for ounce, some of these populations are the most toxic amphibians on the planet," Hanifin says.
'Untouchable' snakes
They compared this toxin data to the resistance found in common garter snakes (Thamnophis sirtalis) throughout the region.
In most locations, the snakes' level of resistance closely matched newt toxicity. In such cases, the poison temporarily slows the snakes down but isn't enough to kill them. This supports "arms race" theories explaining how toxicity and resistance co-evolve.
But in some areas where newt toxicity was relatively high, the poison had no measurable affect on snake mobility.
The team found that resistant snakes had a single genetic mutation on TTX receptor sites on their neural and muscle cells, which prevented the toxin from binding. It made snakes with this mutation "untouchable".
"It is pretty much biologically impossible for the newts to ever catch up," Hanifin says.
While the snakes achieved this super-immunity from a single mutation, Hanifin says that increases in toxicity only occur in smaller incremental changes in a number of genes. And Hanifin thinks microbes infecting humans could also develop super-immunity.
"The rapid evolution of resistance in snakes doesn't bode all that well [for humans]," Hanifin says. "When you have relatively simple toxins or simple drugs you can get this rapid, extreme resistance – and it doesn't take that long to happen."
However, Craig Benkman of the University of Wyoming cautions against extrapolating from snakes and newts to antibiotics and microbes.
"It might apply to these examples that they are alluding to, but it may not," he says, noting that there is great variation in the molecular pathways and number of genes controlling chemical receptors on microbes.
"If there are a lot of genes with small affect than this analogy won't apply," Benkman adds.
Journal Reference: PLoS Biol (DOI: 10.1371/journal.pbio.0060060)
http://www.newscientist.com/article/dn13438-toxic-newts-lose-war-against-superimmune-snakes.html
THE TIMES (London, UK) 11 March 08 Snake evolves to take on toxic newt (Mark Henderson)
http://www.timesonline.co.uk/tol/news/environment/article3525429.ece
SAN FRANCISCO CHRONICLE (California) 11 March 08 Garter snakes out-evolve food prey – newts (David Perlman)
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/03/11/BAV0VEVRN.DTL
VANCOUVER SUN (British Columbia) 11 March 08 Evolution can make sudden leaps: scientists (Maggie Fox)
http://www.canada.com/vancouversun/news/story.html?id=c593fc4b-790d-4163-9ced-9d33b2a3985a