New approach to finding minimum requirements for life.
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From primordial soup to cells
Life is complicated. Even the simplest cell has to deal with continual
changes in temperature, pressure, food, and anything else the
environment wants to throw at it. After millions of years adapting to
every kind of condition, it is hard to determine what genes are actually
driving the cell and which are only add-ons, like power windows and
air-conditioning. Biophysicist Albert Libchaber and colleagues at
Rockefeller University have been getting closer over the past few years
to identifying what are the bare-minimum components of a cell, and this
month they announce new progress.
Less than a year ago, Libchaber and Vincent Noireaux, a postdoc in his
lab, created a vesicle bioreactor, where a phospholipid membrane
surrounds an essential-nutrient containing liquid. Into this sphere,
they placed a small strand of DNA containing three genes. They showed
that this cell-like structure could produce proteins and sustain itself
for up to four days as long as the environment remained stable. Since
then, Libchaber and Noireaux, along with three other colleagues, have
tackled other basic problems that cells have to face every day.
Now, Libchaber, Noireaux and coworkers are tackling other basic problems
that cells have to face every day, like waste management. ³If you
produce, you cannot go on producing forever,² says Libchaber, Detlev W.
Bronk Professor and head of the Laboratory of Experimental Condensed
Matter Physics. ³There must be a balance between production and
destruction. But the destruction must be contained so that only specific
proteins are degraded.²
The concept of a minimal cell, one that contains only the most essential
genes, is being tackled by many different scientists, including Craig
Venter, the entrepreneur-biologist who made headlines in the late 1990s
for using private funding to sequence the human genome. Using the genome
as a base, Venter is trying to reach the same goal as Libchaber by
systematically removing genes, eliminating functionality in an effort to
attain the bare minimum. This is the approach of a biologist, Libchaber
explains. A physicist will take the opposite view if you understand a
system, you can build it from scratch.
Building on their earlier work, Libchaber¹s team expanded from three to
fifteen genes instructing and controlling their bioreactor. They also
are able to create a sink, where products are removed, in their minimal
cells. And they are tackling the basic question of membrane
destabilization. When cells divide, the state of the phospholipid
membrane that surrounds them must be destabilized so the two cells can
split at the very end. Because Libchaber¹s ultimate goal is to create a
minimal cell that can replicate, the problem of membrane destabilization
is important.
³Cells are complicated because the outside environment is complicated,²
says Libchaber. ³By creating a minimal cell, in an environment that does
not change, it will help us understand the problems posed by enclosure
at the origin of life. This paper is an extension towards understanding
what a minimal cell requires.²
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http://www.physorg.com/news8460.html
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
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