Fwd = Lightning provides vital spark for evolution
- Forwarded by: fwestra@... (Frits Westra)
Original Date: 2 Aug 2001 13:21:32 -0000
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The World's No.1 Science & Technology News Service
Lightning provides vital spark for evolution
19:00 01 August 01
Bolts of lightning that strike the ground may help bacteria adapt and
evolve. Experiments suggest that electrical currents help soil
bacteria exchange DNA.
Scientists commonly use electricity to increase the permeability of
bacterial cell membranes, making it easier to insert DNA. Now Sandrine
Deman�che's team at the University of Lyon has provided the first
evidence that nature may have been wise to this trick all along.
The researchers seeded soil samples with the E. coli bacterium, as
well as fragments of DNA containing genes for antibiotic resistance.
They zapped the soil with a simulated lightning strike, and found that
many of the bacteria had acquired the resistance genes.
Bacteria are already known to take up and use foreign DNA released
into the environment when other organisms die. Scientists knew this
"horizontal gene transfer" occurs naturally in soil, but thought it
was relatively rare. However, recent genomic research indicates that
this gene take-up is widespread and has played a major role in the
evolution of the bacterial genome.
"This result might help explain the discrepancy between the very low
observed rates of gene transfer and the apparently wide distribution
of DNA sequences among bacteria," says team member Timothy Vogel.
Lightning may seem relatively rare, but there are about a hundred
flashes a second around the planet. Ground strikes almost always
create currents in the surrounding soil similar to those from the
simulated bolts, Vogel says.
Journal reference: Applied and Environmental Microbiology (vol 67, p
19:00 01 August 01
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