Today, a progress report. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
created them.
Years ago I did a program on
the wonderful silk that spiders spin to make their
webs. Spiders spin far stronger and more adaptable
silk than silkworms do. Typically five times
stronger than steel, it also has a special capacity
for absorbing the energy of an impact. It's ideal
for countless applications, but harvesting any
amount of it has been impossible. We're lucky to
get enough spider silk to make telescope reticules
I concluded that program with a quote from Dryden
about the mystery of: ... their own webs from
their own entrails spun. Solving that mystery
by synthesizing the proteins that make up spider
silk was a terrible challenge. And so it remains.
However, science writer Lawrence Osborne now tells
of an astonishing cut-the-Gordian-knot
solution to the problem. A company called Nexia
Biotechnologies has taken over an old maple sugar
farm in Quebec. They're raising Nubian goats in
that idyllic setting.
The goats are ordinary, playful, friendly animals
-- practically pets. However, one spider gene has
been stirred into the goat DNA. This gene is
programmed to activate only within the female's
mammary glands, and only when she's lactating.
Even then, the goats produce seemingly normal,
drinkable milk. A fairly simple process produces an
astonishing product from the milk. Skim off the
fat. Then, when you add salt, a special protein
curdles out of the milk. Add water to that protein,
and you get essentially the same fluid that's spun
by a spider.
Similar gene replacement processes produce many
pharmaceuticals. This is fairly routine technology,
and it's done without messing up the goats. No Jeff
Goldblum turning into a fly here, no
Island
of Dr. Moreau. These are the same
low-technology goats that've provided milk and
cheese for millennia. This is not terribly
different from processes we use to produce hybrid
grain.
Now, as a substantial supply of spider silk becomes
available, applications arise. It can be used to
make remarkable super-light clothing, biodegradable
sutures, body armor, ligament and tendon prostheses
-- any number of super-light structural materials.
Nexia calls it Bio-steel.
The company is turning a former American Air Force
base in northern New York into a much larger goat
farm -- one that includes adjacent lab space.
Osborne describes how the spider-web-producing
goats like to roll down the sloping sides of old
grass-grown concrete bunkers for the sheer pleasure
of it -- an idyllic spears-into-ploughshares scene.
Is it too good to be true?
One naturally holds one's breath when such a
radical technology comes along. But here is a
potential replacement for so many environmentally
unfriendly fibers. Spider webs are pure protein.
This is the ultimate biodegradable material. And to
receive it from such an amicable creature in
comparison with a spider -- well, that's the part
that truly seems miraculous.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
Osborne, L., Got Silk. New York Times
Magazine, June 16, 2002, pp. 48-51.
For more on spider silk, see Episode 1069.
For more on the Nexia technology, see:
http://www.spacedaily.com/news/materials-02a.html
The Engines of Our Ingenuity is
Copyright © 1988-2002 by John H.
Lienhard.
