Got Silk?
By LAWRENCE OSBORNE
c.2002 Lawrence Osborne
(From The New York Times Magazine)
As soon as I walk into the humid goat shed in my Tyvex suit and sterilized boots, a dozen
Nubians run up to the fence and begin sniffing at me, their Roman noses dilated with fervent
curiosity.
I look around the pen. Hundreds of sly-looking, inquisitive goats are staring at me
intently. They seem unexceptional enough, but the goats that are being bred here are far from
ordinary.
This is a so-called ""transgenic farm'' a place where animal species are either cloned or
genetically mixed to create medically useful substances owned and run by a firm named Nexia
Biotechnologies. It is housed on a former maple-sugar farm in rural Quebec, not far from the
remote hamlet of St.-Telesphore.
Nexia's facility is one of only three transgenic farms in the world. (One of the company's
rivals, PPL Therapeutics, runs the farm in Scotland that collaborated in the production of the
famous sheep clone, Dolly.)
Out here in this tough French-speaking farming country, however, hardly anybody gets worked
up about the fact that on the old St.-Telesphore sugar farm, a new chapter in biotechnology is
being written.
Nexia scientists are pursuing a bizarre experiment straight out of ""The Island of Dr.
Moreau,'' H.G. Wells's dark science-fiction fable of a mad scientist who breeds experimental
animals on his private preserve.
""Oh, it's not that weird,'' Nexia's president and CEO, Jeffrey D. Turner, says as we walk
around the pens, being nibbled constantly by aroused goats. ""What we're doing here is
ingeniously simple,'' he says. ""We take a single gene from a golden orb-weaving spider and
put it into a goat egg. The idea is to make the goat secrete spider silk into its milk.''
Milk silk?
Turner, a bouncy 43-year-old scientist turned biotech entrepreneur, makes a sweeping
gesture at his bleating production units.
""Spider silk is practically the world's strongest material,'' he explains. ""It's much
stronger than steel five times as strong. We're going to make fishing lines out of it.''
I raise my eyebrows dubiously.
'Yes. Biodegradable fishing lines. Or maybe tennis racket strings.'' He grows even more
animated. ""You could make hundreds of things out of spider silk, if only you could produce
enough of it. Biodegradable sutures for surgery ... replacement ligaments or tendons ...
hemostatic dressings ... fashion. We call our product BioSteel.''
Turner isn't simply fantasizing. Nexia foresees tapping into the $500 million market for
fishing materials as well as the $1.6 billion market for industrial fibers in the near future.
And the haute-couture world is already intrigued by a nearly weightless gossamer-like fabric.
But the real gold mine might be body armor: the Pentagon is working with Nexia to develop a
prototype of a new kind of vest that might be made entirely out of goat silk. The vest would
be only a little thicker than nylon, but it could stop a bullet dead.
""It's nothing short of a revolution,'' Turner exclaims. ""This special silk is the first
transgenic material ever made. The amazing thing, however, is that we're changing the world
from a tiny low-rent sugar farm, and our only machinery is a goat.''
Turner admires his flock. ""You could call them Spidergoats,'' he says. ""But that would
give people misconceptions. They're only 1/70,000th spider, after all. When it comes down to
it, they're just normal goats with one spider gene in them. They're just goats.'' He pauses.
""Mostly.''
Scientists have been tinkering with the DNA of animals for years. Researchers have inserted
into rhesus monkeys the gene that makes jellyfish glow in the dark; they've produced chickens
that never grow feathers. But only recently have they begun to develop large-scale industrial
plans for these creatures.
For example, a company in Georgia called ProLinia has cloned cattle and hogs to produce
more genetically desirable breeding stock. After scientists at Johns Hopkins produced enormous
""supermice'' by removing the gene that limits muscle growth, researchers have scrambled to
create the same results in sheep, pigs and chickens.
Inevitably, some bioethicists are alarmed by these projects. And Turner agrees that some of
these experiments are creepy. ""Why do we need cloned sheep?'' he asks. ""What the hell's the
use of millions of cloned sheep? Dolly was a scientific stunt.''
He tells me that Nexia's project is less about altering nature than harnessing it. The
company's goal isn't to create weird goats; they're merely a means of producing useful
quantities of spider silk.
How does a spider gene get into goat milk in the first place? Nexia uses two common spider
specimens, Araneus diadematus (the common garden spider) and Nephila clavipes (the golden orb
weaver, native to many tropical forests). The spiders are frozen in liquid nitrogen, then
ground into a brown powder.
Since every cell of a spider contains the precious silk-producing genes, it's easy to
extract them. These genes are then tested in the ""Charlotte machine,'' what Turner calls a
""synthetic goat'' that tests whether or not the gene will function inside an actual goat.
Next, the gene is altered. A ""genetic switch'' is added, which programs the gene to ""turn
on'' only inside the mammary gland of its new female host during lactation. The altered gene
is then pushed on a fine glass pipette into a goat egg.
The baby goat will have a spider gene present in each of its cells (its eyes, ears and
hooves will all be part spider), but only in the mammary glands of female goats will the silk
gene actually spring to life. The goat will eventually start lactating a kind of silk-milk
mixture, which looks and tastes just like normal milk.
This milk is first skimmed of fat, and salt is added to make the silk proteins curdle into
thin whitish particles that promptly sink to the bottom. After the residue has been removed
from the milk, a little water is added to this sediment until it turns into a golden-tinged
syrup.
This silk concentrate is known to scientists as ""spin dope'' and is more or less identical
to what is inside a spider's belly. Now completely stripped from its milky context, the syrupy
raw silk is ready for spinning.
The properties of spider silk have long been recognized. Fishermen in India have always
prized it for the making of their nets; American Civil War soldiers frequently used it as a
surgical dressing.
The problem lay always in getting sufficient quantities of it. Whereas silkworms are
peaceful herbivores and can easily be farmed, spiders are aggressive territorial carnivores
that need plenty of space and solitude. In farm conditions, they moodily attack and eat each
other.
Farming zillions of spiders, then, is far too tricky. But farming peaceable goats is a
cinch. Yet how to get the desirable material from a rather nasty predator like a spider into
the reproductive system of a kindly animal like a Nubian goat? Enter the odd subject of
mammary glands.
The mammary gland is a perfect natural factory for the synthesizing and production of
proteins. It occurred to Turner, who had been working on lactation at McGill University's
animal sciences department in the mid-to-late '80s, that, theoretically, one could introduce
foreign genes into an animal's mammary gland and get any given protein out of the animal
without killing it, much as one milks a cow.
Given the enormous expense of manufacturing drugs artificially, transgenic animals offered
a brilliant way to make dirt-cheap drugs; $50,000 worth of proteins could be extracted from a
few buckets of milk at a cost of about $12 of hay! The logic seemed irresistible: the udder as
factory outlet.
In 1993, Turner was approached by the two venture-capitalist godfathers of Canada's budding
biotech industry, Bernard Coupal and Ed Rygiel. They had heard of his work at McGill and were
interested in finding a way to create a transgenic goat.
But where most transgenics is concentrated on making drugs, Turner, Coupal and Rygiel
eventually wondered if it might not be more practical, and less risky, to concentrate on
materials.
For one thing, they realized, it's almost impossible for small companies to manufacture
drugs. But a simple material that doesn't need FDA approval is quite another thing. And when
they considered the possible uses of spider silk, they were astounded.
""Humans never think about size,'' Turner says. ""If an animal doesn't make stuff on a
scale we understand, we just ignore it. But insects and marine animals, although they're tiny,
make incredible materials that we could use. Who's to say we can't?''
(Lawrence Osborne is a frequent contributor to The New York Times Magazine.)
