the news hound yet again.

is it just me, or are these profound types of discoveries turning up faster
and faster?

janet

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Study confirms existence of third major branch of life
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Copyright 1996 Nando.net
Copyright 1996 The Associated Press

WASHINGTON (Aug 22, 1996 7:23 p.m. EDT) -- Scientists have decoded the
genes of a microbe that lives on the ocean floor, can survive only in
near-boiling water and thrives on carbon dioxide.

The study confirms existence of a third major branch of life, experts say.

A team of researchers from three institutions announced Thursday that they
decoded the 1,700 genes of a microbe called Methanococcus jannaschii and
found that it is a member of a branch of life called archaea.

"This is a very different life form from what we know," said J. Craig
Venter of the Institute for Genomic Research, the senior author of a study
to be published Friday in the journal Science.

"Two-thirds of the genes in this organism are new to science and biology,"
Venter said. This finding, he said, proves that the microbe is a member of
a class different from the two other basic branches of life -- bacteria and
eukaryotes, which include plants, animals and humans.

Cellular structure is the main difference between these forms of life. The
cells of eukaryotes have nuclear structures. Bacteria do not. The archaea
has some characteristics of the other life forms, but is fundamentally
different in the way it functions and lives, said Venter.

The existence of archaea as a third branch of life was first proposed by
Carl Woese and Ralph S. Wolfe of the University of Illinois, Urbana, in
1977.

Their conclusion was greeted with skepticism and only recently has it
gained acceptance as more and more of the strange new form of life has been
found in places where no other type of life can survive.

Archaea include microbes that live at the extremes of the planet -- the
very, very cold, hot or high pressure places that no other form of life
could endure.

"When the usual organisms start dying, then these start singing," said
Venter.

Some scientists have suggested that archaea may represent the earliest form
of life and that it may be the most likely form of life existing on other
planets. Its precise position on the tree of evolution is still uncertain,
said Venter.

The Methanococcus jannaschii is a microbe that was discovered living on the
edge of a volcanic vent on the floor of the Pacific Ocean in 8,606 feet of
water. It requires temperatures of 185 degrees F, just 27 degrees from
boiling, and must be in pressures of about 3,700 pounds per square inch.

Unlike most bacteria and all plants, animals and humans, the M. jannaschii
lives without the direct or indirect effects of sunlight and without
organic carbon as a food source. The microbe lives on carbon dioxide,
nitrogen and hydrogen expelled by the volcanic vent and gives off methane,
or natural gas, as a waste.

To study the microbe, Woese and his associates at the University of
Illinois constructed steel vats that kept the organism at high pressure and
temperatures and vented away the explosive methane.

"Just to keep them alive in the laboratory presented a considerable
challenge," said Venter.

The Illinois researchers extracted DNA from the microbe and Venter and his
team then decoded the 1,700 gene structure. Researchers from Johns Hopkins
University also participated in the study.

About 500 species of archaea are now identified and Venter said there may
be a million others. The life form is thought to produce about 30 percent
of the biomass on Earth, much of it in the Antarctic Ocean.

M. jannaschii is capable of digesting and concentrating heavy metals and
can produce methane, a natural fuel. For these reasons, the Department of
Energy is funding research on the organism.

Deputy DOE secretary Charles Curtis said that his agency is sponsoring
studies of 10 other bacteria and archaea that may help clean up heavy metal
waste and produce sources of energy.

Science, which published the study, is the journal of the American
Association for the Advancement of Science.


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