Evidence for a hypothesis that is widely believed but surprisingly difficult to demonstrate
The New York Times, October 12, 2010, by Gina Kolata — The two economists call their paper “Mental Retirement,” and their argument has intrigued behavioral researchers. Data from the United States, England and 11 other European countries suggest that the earlier people retire, the more quickly their memories decline.
The implication, the economists and others say, is that there really seems to be something to the “use it or lose it” notion — if people want to preserve their memories and reasoning abilities, they may have to keep active.
“It’s incredibly interesting and exciting,” said Laura L. Carstensen, director of the Center on Longevity at Stanford University. “It suggests that work actually provides an important component of the environment that keeps people functioning optimally.”
While not everyone is convinced by the new analysis, published recently in The Journal of Economic Perspectives, a number of leading researchers say the study is, at least, a tantalizing bit of evidence for a hypothesis that is widely believed but surprisingly difficult to demonstrate.
Researchers repeatedly find that retired people as a group tend to do less well on cognitive tests than people who are still working. But, they note, that could be because people whose memories and thinking skills are declining may be more likely to retire than people whose cognitive skills remain sharp.
And research has failed to support the premise that mastering things like memory exercises, crossword puzzles and games like Sudoku carry over into real life, improving overall functioning.
“If you do crossword puzzles, you get better at crossword puzzles,” said Lisa Berkman, director of the Center for Population and Development Studies at Harvard. “If you do Sudoku, you get better at Sudoku. You get better at one narrow task. But you don’t get better at cognitive behavior in life.”
The study was possible, explains one of its authors, Robert Willis, a professor of economics at the University of Michigan, because the National Institute on Aging began a large study in the United States nearly 20 years ago. Called the Health and Retirement Study, it surveys more than 22,000 Americans over age 50 every two years, and administers memory tests.
That led European countries to start their own surveys, using similar questions so the data would be comparable among countries. Now, Dr. Willis said, Japan and South Korea have begun administering the survey to their populations. China is planning to start doing a survey next year. And India and several countries in Latin America are starting preliminary work on their own surveys.
“This is a new approach that is only possible because of the development of comparable data sets around the world.” Dr. Willis said.
The memory test looks at how well people can recall a list of 10 nouns immediately and 10 minutes after they heard them. A perfect score is 20, meaning all 10 were recalled each time. Those tests were chosen for the surveys because memory generally declines with age, and this decline is associated with diminished ability to think and reason.
People in the United States did best, with an average score of 11. Those in Denmark and England were close behind, with scores just above 10. In Italy, the average score was around 7, in France it was 8, and in Spain it was a little more than 6.
Examining the data from the various countries, Dr. Willis and his colleague Susann Rohwedder, associate director of the RAND Center for the Study of Aging in Santa Monica, Calif., noticed that there are large differences in the ages at which people retire.
In the United States, England and Denmark, where people retire later, 65 to 70 percent of men were still working when they were in their early 60s. In France and Italy, the figure is 10 to 20 percent, and in Spain it is 38 percent.
Economic incentives produce the large differences in retirement age, Dr. Rohwedder and Dr. Willis report. Countries with earlier retirement ages have tax policies, pension, disability and other measures that encourage people to leave the work force at younger ages.
The researchers find a straight-line relationship between the percentage of people in a country who are working at age 60 to 64 and their performance on memory tests. The longer people in a country keep working, the better, as a group, they do on the tests when they are in their early 60s.
The study cannot point to what aspect of work might help people retain their memories. Nor does it reveal whether different kinds of work might be associated with different effects on memory tests. And, as Dr. Berkman notes, it has nothing to say about the consequences of staying in a physically demanding job that might lead to disabilities. “There has to be an out for people who face physical disabilities if they continue,” she said.
And of course not all work is mentally stimulating. But, Dr. Willis said, work has other aspects that might be operating.
“There is evidence that social skills and personality skills — getting up in the morning, dealing with people, knowing the value of being prompt and trustworthy — are also important,” he said. “They go hand in hand with the work environment.”
“It’s a nice approach, a very good study,” he said. But, he said, there are many differences among countries besides retirement ages. The correlations do not prove causation. They also, he added, do not prove that there is a clinical significance to the changes in scores on memory tests.
All true, said Richard Suzman, associate director for behavioral and social research at the National Institute on Aging.
Nonetheless, he said, “it’s a strong finding; it’s a big effect.”
If work does help maintain cognitive functioning, it will be important to find out what aspect of work is doing that, Dr. Suzman said. “Is it the social engagement and interaction or the cognitive component of work, or is it the aerobic component of work?” he asked. “Or is it the absence of what happens when you retire, which could be increased TV watching?”
“It’s quite convincing, but it’s not the complete story,” Dr. Suzman said. “This is an opening shot. But it’s got to be followed up.”
The New York Times, October 12, 2010, by Denise Grady, STANFORD, Calif. — For a 55-year-old man with a bad back and a bum knee from too much tennis, Dr. Abraham Verghese was amazingly limber as he showed a roomful of doctors-in-training a twisting, dancelike walk he had spied in the hospital corridor the day before. He challenged them to diagnose it. Hemiplegia? Sensory ataxia? Chorea? Spastic diplegia? “It would be a shame to have someone with a gait that’s diagnostic, and yet we can’t recognize it,” he said.
It was their introduction to a rollicking workshop on abnormal gaits that soon had them shuffling, staggering and thrashing about, challenging one another. Parkinson’s? Neuropathy? Stroke?
Dr. Verghese (ver-GEESE) is the senior associate chairman for the theory and practice of medicine at Stanford University. He is also the author of two highly acclaimed memoirs, “My Own Country” and “The Tennis Partner,” and a novel, “Cutting for Stone,” which is now a best seller.
At Stanford, he is on a mission to bring back something he considers a lost art: the physical exam. The old-fashioned touching, looking and listening — the once prized, almost magical skills of the doctor who missed nothing and could swiftly diagnose a peculiar walk, sluggish thyroid or leaky heart valve using just keen eyes, practiced hands and a stethoscope.
Art and medicine may seem disparate worlds, but Dr. Verghese insists that for him they are one. Doctors and writers are both collectors of stories, and he says his two careers have the same joy and the same prerequisite: “infinite curiosity about other people.” He cannot help secretly diagnosing ailments in strangers, or wondering about the lives his patients lead outside the hospital.
“People are endlessly mysterious,” he said in an interview in his office at the medical school, where volumes of poetry share the bookshelves with medical texts, family photos and a collection of reflex hammers.
His sources of inspiration include W. Somerset Maugham and Harrison’s Principles of Internal Medicine. In addition to his medical degree, he has one from the writing workshop at the University of Iowa.
He is out to save the physical exam because it seems to be wasting away, he says, in an era of CT, ultrasound, M.R.I., countless lab tests and doctor visits that whip by like speed dates. Who has not felt slighted by a stethoscope applied through the shirt, or a millisecond peek into the throat?
Some doctors would gladly let the exam go, claiming that much of it has been rendered obsolete by technology and that there are better ways to spend their time with patients. Some admit they do the exam almost as a token gesture, only because patients expect it.
Medical schools in the United States have let the exam slide, Dr. Verghese says, noting that over time he has encountered more and more interns and residents who do not know how to test a patient’s reflexes or palpate a spleen. He likes to joke that a person could show up at the hospital with a finger missing, and doctors would insist on an M.R.I., a CT scan and an orthopedic consult to confirm it.
Dr. Verghese trained before M.R.I. or CT existed, in Ethiopia and India, where fancy equipment was scarce and good examination skills were a matter of necessity and pride. He still believes a thorough exam can yield vital information and help doctors figure out which tests to order and which to skip — surely a worthwhile goal as the United States struggles to control health care costs, he said.
A proper exam also earns trust, he said, and serves as a ritual that transforms two strangers into doctor and patient.
“Patients know in a heartbeat if they’re getting a clumsy exam,” he said.
He has lectured and written about the erosion of examination skills, and his ideas have resonated with many doctors.
Stanford recruited him in 2007, in large part because of his enthusiasm for teaching the exam. He seized the bully pulpit.
“Coming from here, it’s taken more seriously,” he said.
With colleagues, he developed the Stanford 25, a list of techniques that every doctor should know, like how to listen to the heart or look at blood vessels at the back of the eye. The 25 are not the only exams or even the most important ones, he emphasizes — just a place to start.
Medical School, Interrupted
At times, Dr. Verghese said, he feels almost embarrassed by all the interest in his work, because the exam techniques he is teaching are nothing more than the same ones he learned in Ethiopia and India decades ago.
Two days a week he hides out to write, in a secret office that was part of the deal he made when Stanford recruited him. His name is not even on the door; he left the names of the previous occupants. There is no land line.
Like Dr. Marion Stone, the main character in “Cutting for Stone,” Dr. Verghese was born in Ethiopia. His parents were teachers from Kerala, a state in southern India. His mother had newspaper articles published there about life in Ethiopia. The family’s expectations were high.
“You were a doctor, engineer, lawyer or a failure,” Dr. Verghese said. He was always drawn to literature, but never imagined he could make living at it.
He left Ethiopia at 15 for two years of premedical studies in Madras, India, and then returned to Addis Ababa for medical school. By then his parents, worried about Ethiopia’s stability, had moved to the United States. But he had no desire to leave.
“I loved that land,” he recalled.
The medical training was rigorous. Students spent a year dissecting a cadaver, and then had to pass grueling essay exams.
“It was almost brutal,” he said. “But it left us changed in some fundamental way, like formatting a disk.”
Medical students in the United States today spend far less time studying anatomy — too little to learn it well, he said, shaking his head.
IN HIS ELEMENT Dr. Verghese teaches a technique for diagnosing cerebellar disorders.
Thor Swift for The New York Times
Civil war broke out in Ethiopia in 1974. Emperor Haile Selassie was deposed, and the military took over. During Dr. Verghese’s third year of medical school, the university was shut down. Soldiers were everywhere. A curfew was imposed, and troops patrolled at night in jeeps with mounted machine guns. Corpses lay in the streets. As a citizen of India, he was a foreigner, and it was time to get out. He joined his parents in Westfield, N.J.
America excited him. But he was a young man used to being on his own, thrust back into a small house with his parents, who urged him to finish his medical studies. He would have to start from scratch, earning a bachelor’s degree and then applying to medical schools, even though he already had more than two years of medical training.
He took a night job as a hospital orderly. He liked earning a paycheck, and he bought a used car, hung out with nurses and orderlies, and dated an American girl.
“I could see my blue-collar life starting to unfold,” he said. “I’d marry a Jersey girl, we’d live in an apartment someplace and take vacations in the Poconos when we could afford it.”
He lost his way during that period, he says, and it made him the black sheep of the family.
A Passionate Return to Training
Then one night at work he had an epiphany. He picked up a book that a medical student had left behind, the Harrison textbook. It’s a medical school classic, the same book he had studied in Ethiopia. He realized how much he had already invested in medicine, and what he would be throwing away if he did not resume his training. He finished medical school in India, and then did his residency in the United States, specializing in internal medicine and infectious disease.
He worked in Tennessee during the early days of the AIDS epidemic, before there were any effective treatments. Before AIDS, he said: “I must have been a conceited ass, full of knowledge. AIDS humbled a whole generation.”
He came to know many of his patients and their families. He visited their homes, attended their deaths and their funerals. One patient, near death, awoke when Dr. Verghese arrived, and opened his shirt to be examined one last time.
“It was like an offering,” Dr. Verghese said, with tears in his eyes. “To preside over the bed of a dying man in his last few hours. I listen, I thump, I don’t even know what I’m listening for. But doing it says: ‘I will never leave you. I will not let you die in pain or alone.’ There’s not a test you can offer that does that.”
His long hours and intense involvement with his patients led to his first book, “My Own Country,” but also drained him and contributed to the failure of his first marriage. Still, it was not a mistake to get so close, he insists.
“I’ve never bought this idea of taking a therapeutic distance,” he said. “If I see a student or house staff cry, I take great faith in that. That’s a great person, they’re going to be a great doctor.”
He met his present wife, Sylvia, in El Paso, where she had started a ministry to help people with AIDS. Their son, Tristan, is 12. Dr. Verghese also has two grown sons, Jacob and Steven, from his first marriage.
The Next Generation
Making hospital rounds with students, Dr. Verghese is in his element. He is impeccably dressed under the white coat, in a crisp dress shirt, pale silk tie and sharply pressed pants. His hair has made its retreat, and what remains is trimmed too close to hide the hearing aids that he has reluctantly begun to wear. He loves being in the wards, he says. It is the only place where his back does not ache.
On a morning in August, he peppered four students with rapid-fire questions, mini-lectures on science and the history of medicine, pointers on presenting cases, and jokes that made them roll their eyes or laugh, or both.
“What can alcohol do to the nervous system?” he asked. Damage the cerebellum, said one. Cause seizures, said another. “Come on, I want 10,” Dr. Verghese said, insistent but not bullying.
“What’s the most important part of the stethoscope?” They stared at him. “The part between the earpieces.” They moaned.
Striding down the corridor, he told them about an unusual condition that produces silver-colored stools.
“You’ll be so impressed you’ll want to take them home,” he said.
With a group of third-year medical students, he waited until they had taken their places around a patient’s bed, then asked them to turn their backs and look away.
What had they noticed on the bedside table? A lunch tray? A book? Clues to whether the patient could eat, whether he was alert? Did he look comfortable? Or did he seem to be in pain?
“What if the patient says, ‘Whatever you do, Doc, don’t bump the bed’?” Dr. Verghese asked, bumping the bed with his hip. “Consider peritonitis.”
The patient, a man in his 80s, grinned, enjoying the show, and seemed pleased to let the students practice palpating his spleen and percussing his lungs.
“Name five things that are better outside the body than in,” he asked, not mentioning that the answer appears in his novel: fluids, fetuses, foreign bodies, feces and flatus.
As they headed to the next room, Dr. Verghese told the students: “We’re going to walk these corridors and I’m going to ask you if you notice anything unusual. I’m going to ask you about someone I see along the way. Peek into patients’ rooms as you go by.”
They gathered around the next patient, leaning in close as Dr. Verghese pointed out signs of facial weakness — inability to raise the eyebrows, a lip that rose more on one side than the other when Dr. Verghese asked to see the patient’s teeth, one eye that blinked more often than the other.
In the corridor, he said, “Here’s your question: What about the lady in the next bed?”
As she had watched them walk by, only one of her eyes had moved. Just a few of the students had noticed.
“You can’t show up at the bedside and then turn on your skills,” he said. “You have to keep your game sharp all the time.”
Outside another patient’s room, he had a group of interns and residents palpating their own thighs as he showed them a technique for finding the right place to stick the needle when culturing an abscess.
“Wow!” said one of the group, whose needle had recently missed its mark. “Amazing. This is great.”
Dr. Verghese smiled. “I am here to astound you,” he said.
“Conceptually it looks to me to be one of the most interesting transmission projects that I’ve ever seen walk through the door”
The New York Times, October 12, 2010, by Matthew L. Wald, WASHINGTON — Google and a New York financial firm have each agreed to invest heavily in a proposed $5 billion transmission backbone for future offshore wind farms along the Atlantic Seaboard that could ultimately transform the region’s electrical map.
The 350-mile underwater spine, which could remove some critical obstacles to wind power development, has stirred excitement among investors, government officials and environmentalists who have been briefed on it.
Google and Good Energies, an investment firm specializing in renewable energy, have each agreed to take 37.5 percent of the equity portion of the project. They are likely to bring in additional investors, which would reduce their stakes.
If they hold on to their stakes, that would come to an initial investment of about $200 million apiece in the first phase of construction alone, said Robert L. Mitchell, the chief executive of Trans-Elect, the Maryland-based transmission-line company that proposed the venture.
Marubeni, a Japanese trading company, has taken a 15 percent stake. Trans-Elect said it hoped to begin construction in 2013.
Several government officials praised the idea underlying the project as ingenious, while cautioning that they could not prejudge the specifics.
“Conceptually it looks to me to be one of the most interesting transmission projects that I’ve ever seen walk through the door,” said Jon Wellinghoff, the chairman of the Federal Energy Regulatory Commission, which oversees interstate electricity transmission. “It provides a gathering point for offshore wind for multiple projects up and down the coast.”
Industry experts called the plan promising, but warned that as a first-of-a-kind effort, it was bound to face bureaucratic delays and could run into unforeseen challenges, from technology problems to cost overruns. While several undersea electrical cables exist off the Atlantic Coast already, none has ever picked up power from generators along the way.
The system’s backbone cable, with a capacity of 6,000 megawatts, equal to the output of five large nuclear reactors, would run in shallow trenches on the seabed in federal waters 15 to 20 miles offshore, from northern New Jersey to Norfolk, Va. The notion would be to harvest energy from turbines in an area where the wind is strong but the hulking towers would barely be visible.
Trans-Elect estimated that construction would cost $5 billion, plus financing and permit fees. The $1.8 billion first phase, a 150-mile stretch from northern New Jersey to Rehoboth Beach, Del., could go into service by early 2016, it said. The rest would not be completed until 2021 at the earliest.
Richard L. Needham, the director of Google’s green business operations group, called the plan “innovative and audacious.”
“It is an opportunity to kick-start this industry and, long term, provide a way for the mid-Atlantic states to meet their renewable energy goals,” he said.
Yet even before any wind farms were built, the cable would channel existing supplies of electricity from southern Virginia, where it is cheap, to northern New Jersey, where it is costly, bypassing one of the most congested parts of the North American electric grid while lowering energy costs for northern customers.
Generating electricity from offshore wind is far more expensive than relying on coal, natural gas or even onshore wind. But energy experts anticipate a growing demand for the offshore turbines to meet state requirements for greater reliance on local renewable energy as a clean alternative to fossil fuels.
Four connection points — in southern Virginia, Delaware, southern New Jersey and northern New Jersey — would simplify the job of bringing the energy onshore, involving fewer permit hurdles. In contrast to transmission lines on land, where a builder may have to deal with hundreds of property owners, this project would have to deal with a maximum of just four, and fewer than that in its first phase.
Ultimately the system, known as the Atlantic Wind Connection, could make building a wind farm offshore far simpler and cheaper than it looks today, experts said.
Environmentalists who have been briefed on the plan were enthusiastic. Melinda Pierce, the deputy director for national campaigns at the Sierra Club, said she had campaigned against proposed transmission lines that would carry coal-fired energy around the country, but would favor this one, with its promise of tapping the potential of offshore wind.
“These kinds of audacious ideas might just be what we need to break through the wretched logjam,” she said.
Projects like Cape Wind, proposed for shallow waters just off Cape Cod in Massachusetts, met with fierce objections from residents who felt it would mar the ocean vista. But sponsors of the Trans-Elect project insist that the mid-Atlantic turbines would have less of a visual impact.
The hurdles facing the project have more to do with administrative procedures than with engineering problems or its economic merit, several experts said.
By the time the Interior Department could issue permits for such a line, for example, the federal subsidy program for wind will have expired in 2012, said Willett M. Kempton, a professor at the School of Marine Science and Policy at the University of Delaware and the author of several papers on offshore wind.
Another is that PJM Interconnection, the regional electricity group that would have to approve the project and assess its member utilities for the cost, has no integrated procedure for calculating the value of all three tasks the line would accomplish — hooking up new power generation, reducing congestion on the grid and improving reliability.
And elected officials in Virginia have in the past opposed transmission proposals that would tend to average out pricing across the mid-Atlantic states, possibly raising their constituents’ costs.
But the lure of Atlantic wind is very strong. The Atlantic Ocean is relatively shallow even tens of miles from shore, unlike the Pacific, where the sea floor drops away steeply. Construction is also difficult on the Great Lakes because their waters are deep and they freeze, raising the prospect of moving ice sheets that could damage a tower.
Nearly all of the East Coast governors, Republican and Democratic, have spoken enthusiastically about coastal wind and have fought proposals for transmission lines from the other likely wind source, the Great Plains.
“From Massachusetts down to Virginia, the governors have signed appeals to the Senate not to do anything that would lead to a high-voltage grid that would blanket the country and bring in wind from the Dakotas,” said James J. Hoecker, a former chairman of the Federal Energy Regulatory Commission, who now is part of a nonprofit group that represents transmission owners.
He described an Atlantic transmission backbone as “a necessary piece of what the Eastern governors have been talking about in terms of taking advantage of offshore wind.”
So far only one offshore wind project, Bluewater Wind off Delaware, has sought permission to build in federal waters. The company is seeking federal loan guarantees to build 293 to 450 megawatts of capacity, but the timing of construction remains uncertain.
Executives with that project said the Atlantic backbone was an interesting idea, in part because it would foster development of a supply chain for the specialized parts needed for offshore wind.
Interior Secretary Ken Salazar, whose agency would have to sign off on the project, has spoken approvingly of wind energy and talked about the possibility of an offshore “backbone.” In a speech this month, he emphasized that the federal waters were “controlled by the secretary,” meaning him.
Within three miles of the shore, control is wielded by the state. Nonetheless, if the offshore wind farms are built on a vast scale, the project’s sponsors say, a backbone with just four connection points could expedite the approval process.
In fact, if successful, the transmission spine would reduce the regulatory burden on subsequent projects, said Mr. Mitchell, the Trans-Elect chief executive.
Mr. Kempton of the University of Delaware and Mr. Wellinghoff of the Federal Energy Regulatory Commission said the backbone would offer another plus: reducing one of wind power’s big problems, variability of output.
“Along the U.S. Atlantic seaboard, we tend to have storm tracks that move along the coast and somewhat offshore,” Mr. Kempton said.
If storm winds were blowing on Friday off Virginia, they might be off Delaware by Saturday and off New Jersey by Sunday, he noted. Yet the long spine would ensure that the amount of energy coming ashore held roughly constant.
Wind energy becomes more valuable when it is more predictable; if predictable enough, it could replace some land-based generation altogether, Mr. Kempton said.
But the economics remain uncertain, he warned, for now, he said, the biggest impediment may be that the market price of offshore wind energy is about 50 percent higher than that of energy generated on land.
With a change in market conditions — an increase in the price of natural gas, for example, or the adoption of a tax on emissions of carbon dioxide from coal- or gas-generated electricity — that could change, he said.
Spidergoat This baby goat will produce milk that contains spider silk proteins. Holly Steinkraus/University of Wyoming
After years of research, we may be close to full-scale production of super-strong spider silk
PopSci.com, October 12, 2010, by Rebecca Boyle — Mutant silkworms can produce miles of super-strong silk, in a new breakthrough that could lead to mass production of tough, flexible spider-silk material. Thanks to the efforts of these genetically modified spider-worms, along with spidergoats and spider-alfalfa, spider clothes may soon be upon us.
Randy Lewis, a molecular biologist at the University of Wyoming, has been milking his spidergoats for a couple years now, and he’s been trying to improve yields of genetically engineered spider-silk alfalfa. He’s researching improved synthetic spider silk genes, and he hopes to start growing spider cotton in the near future. With his latest research, spider fabrics might only be a year away.
Last week, Lewis and Malcolm Fraser at the University of Notre Dame announced they bred silkworms that had been genetically engineered to produce spider silk.
“From our perspective, there are huge advantages to the fact that the fiber is already spun,” Lewis said. “You don’t have to purify the protein, you don’t have to take it and spin fibers.”
Lewis said the study, which has not yet been published, proves the concept of engineering and breeding transgenic silkworms.
“The real question is going to be, can we make the necessary improvements in the mechanical properties of the silkworm silk by incorporating the spider silk in it? If we can do that, then obviously it makes a whole lot of things possible in terms of the amount of material you can make.”
A single silkworm cocoon contains more than a half-mile of silk thread, so colonies of transgenic silkworms produce plenty of silk, said Fraser, a molecular biologist at Notre Dame. He believes industrial production of engineered spider silk could happen within a year.
Spider silk is one of the most valuable materials in nature. It could be used for a vast array of products, from artificial ligaments to super-strong wound dressings or even body armor. Lewis envisions spider-silk replacement tendons, parachute cords and more.
Silk could even be used to transport drugs or act as nanoscale transistor scaffolds. In a study last year, scientists at Legacy Clinical Research & Technology Center in Portland, Ore., demonstrated that silk-based brain implants containing adenosine can suppress seizures in rats. In a paper published in the journal Science in July, Tufts University researchers said silk could be used to build flexible and degradable displays or even implantable optical systems for medicine.
“There’s lots of things you can do with fibers that you can’t do with something that comes as an amorphous blob or a solid,” Lewis said.
Nano-sized fibers are still limited. “We can make textile quantities of the silkworm silks,” Fraser said. “Nanotechnology is certainly something that has some awesome potential, but I don’t know how soon that potential will be realized, and even if it is realized, I’m not sure that it would replace many of the medical applications of natural silk fibers, which are considerable.”
Lewis has been working on those applications for two decades. It’s been 12 years since he first isolated the genes that produce high-performance spider silk, and he garnered international attention for his transgenic goats, whose DNA has been altered to produce the proteins necessary to make spider silk. When the goats give birth and start lactating, they produce spider silk proteins in their milk, which is collected, purified and spun into silk, Lewis said.
It would be easier to milk spiders than mutant goats, if only spiders were not so murderous and territorial. As it is, spider farms have not proven a successful venture, whereas there are long traditions of farming both silkworms and goats. Scale makes a difference too: Lewis can get half an ounce of silk from every quart of milk. It would take 100 spiders to obtain that amount.
Transgenic silkworms could be even more productive. Breeding them involved some sneaky DNA, however. Kraig Biocraft Laboratories Inc., a Lansing, Mich., firm, partnered with Fraser, who discovered and patented a DNA transposon called “piggyBAC.” The transposon can insert itself into a cell’s genetic material. The researchers used piggyBAC to incorporate snippets of spider DNA into silkworm embryos, resulting in silkworms that spin a hybridized part-silkworm, part-spider silk.
The researchers wanted to be sure they could breed the spiderized silkworms, so they also added fluorescent protein to the spider DNA. The mutant silkworms had glowing red eyes, and their silk was fluorescent green.
Silkworm: A mature silkworm is pictured just before it starts spinning its transgenic silk. University of Notre Dame
Fraser said he is completing molecular analyses before submitting his study to a research journal. Meanwhile, he hopes to continue improving the snippets of spider DNA — especially if scientists obtain a sequence for a brand-new spider just discovered in Madagascar. The Darwin’s bark spider makes the largest webs in the world, spinning silk that is 10 times stronger than Kevlar.
Fraser also studies HIV and hepatitis, and he hinted that piggyBAC-hacked silkworms might be useful for other applications: “Silk isn’t the only protein that silkworms can produce,” he said.
Lewis said his highest priority is figuring out the fastest and most efficient way to produce large quantities of silk. He also hopes to continue isolating new spider silk genes and incorporating them into his formula. As of now, his formula is a blend of several different spider proteins, mainly from the golden orb weaver.
Lewis also hopes to start breeding cotton plants that contain the protein necessary to make spider silk. Cotton seeds already contain protein, and they’re considered a waste product, Lewis said.
“If we can take and use something that nobody is going to eat and that doesn’t have much value, and use that as a production system, then we have very little impact on food and fiber, and we can use the methods that are already out there,” he said. Then spider clothes might not be far off at all.