Tuesday, May 30, 2006

Poison Ivy Thrives as Planet Warms

Another reason to worry about global warming: more and itchier poison ivy.

The noxious vine grows faster and bigger as carbon dioxide levels in the atmosphere rise, researchers reported yesterday.

And a CO2-driven vine also produces more of its rash-causing chemical, urushiol, conclude experiments conducted in a forest at Duke University where scientists increased carbon-dioxide levels to those expected in 2050.

Carbon dioxide is a greenhouse gas -- a chemical that traps heat similar to the way a greenhouse does -- that is considered a major contributor to global warming. Poison ivy's itchy, sometimes blistering rash is one of the most widely reported ailments, with more than 350,000 reported cases a year.

Compared with poison ivy grown in usual atmospheric conditions, those exposed to the extra-high carbon dioxide grew about three times larger -- and produced more allergenic form of urushiol, scientists from Duke and Harvard University reported. Their study appears in this week's Proceedings of the National Academy of Sciences.

Lobsters Ostracize Ailing Brethren

Caribbean spiny lobsters are mercenary when it comes to staying healthy, shunning their diseased comrades, researchers have found.

The lobsters know, probably through their fine sense of smell, even before symptoms appear, when other lobsters are sick with a highly infectious and deadly virus spread mainly by physical contact. Researchers say the crustaceans' ability to detect infection and steer clear of the infected individuals was unknown in animals in the wild.

"It's unlikely that this kind of behavior evolved in just one organism," said Old Dominion University marine biologist Mark Butler, one of the researchers who reported the behavior in the journal Nature. "It's possible, given how many social animals there are out there, that similar kinds of behaviors exist and that we just haven't recognized it."

-- From News Services

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