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Smart_Planet_4 00989.txt

Genetically modifying plants to absorb arsenicsince ancient times, humans have been using and abusing arsenic for everything from mining to medicine to murder. But a gene found in an ancient plant, a fern, might lead to solutions to sponge the toxin from contaminated areas. Arsenic and its compounds occur naturally in many places, but high levels accumulate in the environment through wood preservatives, fertilizers, coal burning, paints and other industrial uses. A carcinogen over long-term exposure, the metalloid becomes particularly troublesome when it contaminates groundwater. Known for its arsenic-proof powers, the ladder brake fern (Pteris vittata) is used already in some of the Environmental protection agency's phytoremediation efforts of arsenic-laden soil. But botanists at Purdue University hope their research, published in the journal Plant Cell, might eventually improve cleanup strategies, via genetic modification. They've isolated the gene (ACR3) that codes for a membrane protein within the ferns'vacuoles. A second copy of ACR3 allows the ladder brake fern to safely transport arsenic from its roots to its fronds, where most of the toxin is stored. Study authors Jody Banks and David Salt in a statement: Potentially you could take these genes and put them in any organism that could suck the arsenic out of the Soil banks said. Salt said rice plants could be modified with the gene to store arsenic in the roots of plants-instead of rice grains-in contaminated paddies. I think I'll pass on that rice, at least with the first few harvests. In fact, the botanists speculate that one possible explanation for the fern's arsenic storage ability is to discourage animals from dining on fern salad. Rice or not, genetically modifying organisms might also be problematic even if certain plants moss, lycophytes, gymnosperms, and other ferns already have a single copy of the gene. Flowering species (from more recent branches of plant evolution) appear not to have ACR3 at all. The researchers'next move will be to inject ACR3 into the genome of a flowering plant, thale cress (Arabidopsis), to see if it, too, can become an arsenic vacuum. Images: Wikipedia Commons

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