X-Message-Number: 14949
From: <>
Date: Sat, 18 Nov 2000 15:12:29 +0100 (CET)
Subject: Wherever you look, there's life

From: Ron Baalke <>
Subject: Wherever You Look, There's Life
To:  (Astronomy List)
Date: Thu, 9 Nov 2000 08:50:47 -0800 (PST)
X-Mailer: ELM [version 2.5 PL1]


http://www.newscientist.com/news/news.jsp?id=ns226415

Exposed

Wherever you look, there's life

By Joanna Marchant

New Scientist
November 11, 2000

LIFE exists even at the South Pole, one of the most inhospitable places on
Earth.

Microbiologist Ed Carpenter of the State University of New York in Stony
Brook and his colleagues have found between 200 and 5000 bacteria per
millilitre of melted snow from the pole.

To their surprise, biochemical tests and electron microscope images show
that the organisms can grow and divide even at -17 degrees C--the coldest 
condition the team tested. "Probably they could live at even lower
temperatures," says Carpenter.

Although bacteria have been found in the snow near the pole before, they
were thought to have blown in accidentally. No one believed they could grow
in the harsh conditions there, where temperatures range between -85 degrees 
C and -13 degrees C.

DNA tests revealed that all the bacteria are previously unknown species.
Their closest relatives are a group called Deinococcus, which are known for
their extremely efficient DNA repair mechanisms.

It was not known why the Deinococcus evolved such high protection, since
nowhere on Earth is ultraviolet radiation strong enough to damage DNA so
badly. However, severe desiccation can harm DNA just as much as UV radiation
does--and the Antarctic is very dry, because all the water is frozen. "At
the South Pole, the repair mechanisms make sense," says Carpenter.

The finding suggests that life could exist in other environments previously
thought too harsh, such as the polar ice cap on Mars, the researchers say.
"The more extreme conditions that we look at, the more we find that bacteria
are able to survive," says Carpenter.

Rich Zurek, who worked on NASA's Mars Polar Lander programme, says that
while the average temperature at Mars's North Pole is only around -70 
degrees C in summer, local areas of volcanic activity or hot springs might 
have provided enough warmth for life to evolve. In the Martian winter, 
temperatures fall to around -120 degrees C, but Zurek says there is no 
reason why organisms would not be able to survive.

"Under those kind of conditions, life goes dormant. It finds a way to
preserve itself, " he says.

More at: Applied and Environmental Microbiology (vol 66, p 4514)

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