Even a camel can't match this trick for surviving extreme drought: The nematode Aphelenchus avenae can lose nearly all its body water, then recover to its slippery self years later when conditions moisten. New work uncovers several genes that might contribute to this creature's powers of perseverance. Meddling with these genes might one day enable scientists to extend the shelf life of insect-killing nematodes that farmers spray onto crops.
A. avenae and other anhydrobiotic plants and animals--organisms that can live without water--produce large amounts (up to 20% of a cell's mass) of certain sugar molecules that harden into a semisolid state. Molecules enmeshed in this gel are locked into place and preserved from the random chemical movements that normally cause them to deteriorate. The sugars contain many polar chemical groups, which take the place of water and stabilize cellular proteins and membranes until the parched period is over. Recent studies have suggested that numerous genes, in addition to those involved in sugar synthesis, are required for plants to survive extreme dehydration.
Now researchers have found that at least one of these genes also functions in nematodes. Ann Burnell of the National University of Ireland in Maynooth and colleagues dried out A. avenae worms and screened for genes that ramp up in response. One of the several they identified resembles a plant gene called LEA that's also turned on by desiccation. The results, described in the 7 March issue of Nature, raise the possibility that nematodes and plants use some of the same equipment to fight drought, says plant physiologist Dorothea Bartels of the Max Planck Institute for Plant Breeding Research in Cologne, Germany.
Researchers don't know how these pieces of molecular machinery prevent living things from withering, but previous work in plants suggests that the genes produce ultrastable proteins that help form the protective sugar mesh. "Until recently people have thought that the main answer to anhydrobiosis has been the production of [sugar]," says nematode biologist David Wharton of the University of Otago in Dunedin, New Zealand. "This work indicates that there could be other mechanisms operating."
Related links A
longer version of this story on Science's Science of Aging
Knowledge Environment (SAGE KE)
SAGE
KE article on the link between such survival feats and
longevity
Burnell
lab
A.
avenae information from UC Davis
Parasitic Nematodes page from
the University of Nebraska, Lincoln
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