Bacteria 'holds clue to life'
2007-08-28 09:04
London - Ancient bacteria are able
to survive nearly half a million years in harsh, frozen
conditions, researchers said on Monday in a study that adds to
arguments that permafrost environments on Mars could harbour
life.
The findings also represent the oldest independently
authenticated DNA to date obtained from living cells and could
offer clues to better understand ageing, said Eske Willerslev, a
researcher at the University of Copenhagen who led the study.
"When it can live half a million years on Earth it makes it
very promising it could survive on Mars for a very long time,"
Willerslev said. "Permafrost would be an excellent place to look
for life on Mars."
The international team, which also included researchers from
the United States, Canada, Russia and Sweden, tested the
microbes living up to 10 metres deep in permafrost collected
from Northern Canada, the Yukon, Siberia and Antarctica.
When a cell dies, its DNA fragments into pieces but the
samples the researchers studied were all very long strands -
evidence the cells were able to continuously repair genetic
material and remain alive, said Willerslev, whose findings were
published in the Proceedings of the Academy of Sciences.
"These cells are active cells repairing DNA to deal with
continuous degradation of the genomes, which is the genetic
material that is key to life," he said.
"It is the same thing with humans."
The scientists do not yet know the mechanism driving the
continuous repair but Willerslev said the cells survived by
eating nutrients like nitrogen and phosphate lodged in the
permafrost.
This is interesting because the temperature on Mars is much
colder with more stable temperatures, representing an even
better environment to sustain this kind of life, he added.
While most scientists think our neighbour in the solar
system is lifeless, the discovery of microbes on Earth that can
exist in environments previously thought too hostile has fuelled
debate over extraterrestrial life.
Researchers had known these microbes could survive for a
long time without food but until now there was little agreement
on how long they could live, Willerslev said.
Knowing this, and eventually pinpointing the key to this
longevity, may also help scientists better understand the ageing
process, he added.
"It is interesting to see why some cells can survive for a
very long time," he said. "That can be a key for
understanding ageing."