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NOVA scienceNOW: July 23, 2008

PBS Airdate: July 23, 2008
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NEIL DeGRASSE TYSON (Host/Astrophysicist, American Museum of Natural History): On this episode of NOVA scienceNOW: the swamp creature that everyone fears...

MARK E. SIDDALL (American Museum of Natural History): He's not going to bite you.

NEIL DeGRASSE TYSON: He started to bite me!

MARK SIDDALL: Come on.

NEIL DeGRASSE TYSON: ...the slithery, slimy leech.

MARK SIDDALL: He did not.

NEIL DeGRASSE TYSON: He was hanging on.

MARK SIDDALL: That was his back sucker, not his mouth sucker.

Uh, oh.

NEIL DeGRASSE TYSON: But now these flexible bloodsuckers are winning new fans in the world of microsurgery.

THOMAS CLARK (Accident Victim): The leeches saved my finger. The part of my finger that was dying started coming back to life.

NEIL DeGRASSE TYSON: And the big question...

JILL TARTER (Center for SETI Research): Are we alone? Humans have been asking it forever.

NEIL DeGRASSE TYSON: For more than 40 years, we've been trying to "tune in" to an alien station.

SETH SHOSTAK (Center for SETI Research): We're looking for a signal somewhere on the radio dial that they might be broadcasting into space.

NEIL DeGRASSE TYSON: Now, hundreds of new radio dishes...

ANDREA KISSACK (Correspondent): Wow! That is very Flash Gordon.

NEIL DeGRASSE TYSON: ...are expanding the search for intelligent life somewhere else in the universe.

JILL TARTER: The probability of success is difficult to estimate, but if we never search, the chance of success is zero.

NEIL DeGRASSE TYSON: Also, if you're looking to spy on life at the bottom of the sea, submarines are not the answer.

SOeNKE JOHNSEN (Duke University): It's got lights flashing, motors whirring, and then you come up to some animal, 5 inches away, and say, you know, "Act natural."

NEIL DeGRASSE TYSON: So this biologist came up with a new kind of camera. And it's working, revealing some weird and wonderful creatures.

EDITH WIDDER (Ocean Research & Conservation Association, Inc.): I was just wild. I couldn't believe it.

Every time we put this thing down we see something nobody's ever seen before.

NEIL DeGRASSE TYSON: All that and more, on this episode of NOVA scienceNOW.

Funding for NOVA scienceNOW is provided by...

Americans are living longer, spending more on healthcare. At Pfizer, we're working on ways to help, with medicines that help prevent illnesses, with programs that provide our medicines to people without coverage, and new partnerships to keep costs down and keep people healthy.

And by the National Science Foundation, where discoveries begin. And...

Discover new knowledge, biomedical research and science education. Howard Hughes Medical Institute: HHMI.

And the Alfred P. Sloan Foundation, to portray the lives of men and women engaged in scientific and technological pursuit.

And the George D. Smith Fund.

And by PBS viewers like you. Thank you.

LEECHES

NEIL DeGRASSE TYSON: Hello, I'm Neil deGrasse Tyson, your host of NOVA scienceNOW. You know, in the old days, centuries ago, barbers were considered medical professionals. Instead of a shave and a haircut, for two bits, what you'd get was the cutting-edge treatment of the day, and that was bloodletting.

And sometimes they did it, not with razors, but with a tiny little helper.

Modern medicine is not generally into bloodletting, but, strangely enough, in some cases, surgeons have come to rely once again on this talented little creature.

Ladies and gentlemen, it turns out the leech is back!

So how....you just look for ponds wherever you find them and...

MARK SIDDALL: Well, they have to have a certain character.

NEIL DeGRASSE TYSON: I wasn't quite sure what to expect, when biologist Mark Siddall, my colleague from the American Museum of Natural History, led me through the woods into a muddy swamp.

MARK SIDDALL: It's not too bad.

NEIL DeGRASSE TYSON: But I suspected it might be just kind of gross.

This is nasty; let the record show. Are we getting sucked on right now?

MARK SIDDALL: Not likely to be being fed on just yet. Normally, it takes them a little while to realize we're here. They respond to movement in the water first.

NEIL DeGRASSE TYSON: Within a few minutes, hungry leeches tracked us down and were swimming right towards us.

MARK SIDDALL: There's one right there, right there, right there in the water.

NEIL DeGRASSE TYSON: Do I grab him?

MARK SIDDALL: Yup. It's a beautiful, beautiful macrobdella decora, literally, "decorated leech." They have orange polka dots that go down the back.

NEIL DeGRASSE TYSON: Unlike Mark, the squirmy thing's body decoration was the last thing on my mind.

MARK SIDDALL: He's not going to bite you.

NEIL DeGRASSE TYSON: He started to bite me!

MARK SIDDALL: He did not.

NEIL DeGRASSE TYSON: He was hanging on.

MARK SIDDALL: That was his back sucker, not his mouth sucker.

NEIL DeGRASSE TYSON: You can't blame me for getting a little squeamish. After all, aren't these the bloodsucking creatures that turn up in movies to terrorize anybody who wanders into fresh water?

HUMPHREY BOGART in AFRICAN QUEEN: If there's anything in the world I hate, it's leeches, filthy little devils!

NEIL DeGRASSE TYSON: Once upon a time, people often put leeches on their bodies on purpose. For centuries, people believed that intentional bleeding was good for you, as a way to regulate what were called the body's "humors."

MARK SIDDALL: If someone was sick, all you had to do was rebalance the humors. You have four humors: blood, yellow bile, black bile and phlegm. And what you needed to do was get the right balance of those, and then you would be fine.

NEIL DeGRASSE TYSON: In 19th century Europe, the leech became the method of choice for all-purpose bloodletting. Fever? Try a leech. Headache? Stick one on your temple. Overweight? Never fear, leeches to the rescue.

JOSEPH UPTON (Beth Israel Deaconess Medical Center): Leeching was kind of a panacea. If somebody had a black eye or a big shiner or something, they'd put a leech on it. That was commonplace.

NEIL DeGRASSE TYSON: Eventually, people began to realize for a lot of the patients, all this bloodletting wasn't really helping. And the leech fell into disrepute, the poster child of medical ignorance.

Of course, it wasn't really the leeches' fault. They were just doing what they're good at, dining on your blood.

MARK SIDDALL: Uh, oh.

NEIL DeGRASSE TYSON: He's got one.

MARK SIDDALL: Yup.

NEIL DeGRASSE TYSON: For some reason, the leeches here seemed to prefer Mark's legs to mine.

MARK SIDDALL: You got any on you, by the way?

NEIL DeGRASSE TYSON: I don't know. Will I feel it?

MARK SIDDALL: Yes, you will. You will feel a pinch.

NEIL DeGRASSE TYSON: And one really chowed down on the knee of Mark's assistant, Sara Watson.

MARK SIDDALL: So what the leech is doing right now is it's filling up with Sara's blood.

NEIL DeGRASSE TYSON: These leeches live exclusively on blood, and a huge stomach is key for their survival.

MARK SIDDALL: So leeches can feed six to seven, maybe eight times their unfed body weight in blood. And because of that, what they do is they hold onto that blood in the stomach, squeeze a little bit down into the intestines as they need it after they've finished feeding, and digest it while they're hiding under a rock or going off to find a mate.

NEIL DeGRASSE TYSON: A leech can live for months on one good blood meal, but a full stomach creates a potential risk. Left alone, the blood would soon clot and thicken. So the leech produces a powerful anti-coagulant, a blood thinner.

MARK SIDDALL: The importance of this is obvious, if you're a leech, because if you fill up with blood to, like, six or seven times your body weight, if that blood clots inside of you, you're going to turn into a brick and fall to the bottom of the water. You can't swim; you can't mate; you can't have young. You can't get away from predators, and it's all over. So, these anti-coagulants are extremely important in terms of the leeches' survival.

NEIL DeGRASSE TYSON: And this blood thinner, so crucial to the creature's survival, is one reason the leech's reputation has recently been rehabilitated.

Construction worker Thomas Clark had seen some leeches as a kid, but a few months ago, they played a major role in his life.

THOMAS CLARK: That particular day, I was doing tree work. So I was in a little Bobcat(R). It's pretty simple.

NEIL DeGRASSE TYSON: Clark was using a small loader to lift a tree trunk into a dump truck when things suddenly went wrong.

THOMAS CLARK: As I was rolling the log off, the Bobcat tilted forward, came off the rear wheels. My hand came out of the Bobcat, and this part of the Bobcat kissed the side of the dump truck and crushed off all these fingers. Exactly right here, chu, chu, chu, chu.

It just looked like I put my hand in a meat grinder 'cause it, like, it smushed.

NEIL DeGRASSE TYSON: Clark was rushed to the hospital where surgeons struggled to rebuild his hand.

AMIR TAGHINIA (Beth Israel Deaconess Medical Center): The middle finger had the worst injury, by far. It was really just hanging off by one tendon. And it was sort of twisted on itself. And we had to do quite a bit of surgery to get that finger to live.

NEIL DeGRASSE TYSON: The next day, Clark's middle finger was not doing well.

THOMAS CLARK: It was turning black, and they said that it was dying. So they were going to take it off.

NEIL DeGRASSE TYSON: Too much blood was coming into his finger, but not getting out. The veins that normally carry the blood away were too badly damaged.

AMIR TAGHINIA: If there's blood going into the finger, but there's no blood coming out of the finger, pressure builds up, and the tissues can't tolerate that. If you were to leave that state and not doing anything to relieve that pressure, relieve that tension, relieve that outflow, the finger would die.

NEIL DeGRASSE TYSON: It didn't look like more surgery would fix the problem. So, even though doctors usually want to stop bleeding after an operation, in this case, it was just the opposite.

AMIR TAGHINIA: So your next option is to use leeches.

THOMAS CLARK: I was actually kind of, like, "Cool." You know, I was like, you know, "Whatever works. I don't want to lose anything, you know. So, if it's going to work, let's do it."

NEIL DeGRASSE TYSON: Leeches were brought in to feed on his finger and suck out the extra blood.

THOMAS CLARK: Every time my heart beat, it was like the leech was sucking with the beat of my heart, and it was like a pump. It was like "bum-bum, bum-bum."

NEIL DeGRASSE TYSON: As the leech sucks, it releases that powerful blood thinner into the finger, which prevents clotting.

AMIR TAGHINIA: The leech is interesting. It injects a blood thinner, called herudin, into the soft tissues around that area. So when the leech gets full and falls off, the finger continues to bleed. That buys you time, that process.

NEIL DeGRASSE TYSON: With a few days of leeching, the finger can naturally grow new veins and resume healthy blood circulation.

THOMAS CLARK: It was almost instant. You could tell that it was working, because my...the swelling was going down. The open wounds were actually healing. And I could actually feel a pulse in my finger. And the blackness started going away. And, like, the part of my finger that was dying started coming back to life.

JOSEPH UPTON: When you're in a situation where you've already done everything that you can technically do, and then you're still having problems, actually, the leeches are very valuable. They're incredibly valuable.

NEIL DeGRASSE TYSON: Thomas Clark's leech therapy worked. Though he hasn't regained full function of his hand, his fingers were all saved.

THOMAS CLARK: I definitely wanted to keep my hand and all fingers, because the human body's got ten fingers, not nine. So it means a lot. It does. The leeches saved my finger, no doubt about it.

AMIR TAGHINIA: They're really indispensable for what we do. And there would be many a finger's lopped off if it weren't for leeches.

NEIL DeGRASSE TYSON: The leech's comeback delights biologist Mark Siddall, but his appreciation goes far beyond its medical usefulness.

I don't mind him crawling on me, as long as I know when he's about to bite.

Leeches are a kind of worm, and there are hundreds of different species living all over the world.

MARK SIDDALL: He's trying to find a place to feed on me.

There are terrestrial leeches, there are fresh water leeches, there are marine leeches. There's just this huge diversity of form, color, pattern and even of behavior.

And most of them are not very specific, in terms of what they'll feed on, but some of them are. Some of them are very specific to fish, and there's even one in Africa that lives exclusively in the rectum of hippopotamus.

NEIL DeGRASSE TYSON: Eww.

MARK SIDDALL: Yes, well, there was a paper written called, "Leeches Ride the Tunnel of Love," because they mate there.

NEIL DeGRASSE TYSON: You sure?

Leeches have been crawling and swimming around Earth for hundreds of millions of years. For Siddall, these graceful creatures are fascinating, even beautiful, despite their taste for blood.

MARK SIDDALL: Leeches are unnecessarily maligned. They don't take more blood than you can reproduce by yourself. And you know what? Unlike a mosquito or a black fly, they don't transmit any parasites. And quite frankly, if you took some time to have a look at them, you'd see just how pretty they are. I know most people don't really think about conserving leeches, but just like any group of organisms on the face of this planet, wouldn't it be just a little bit colder and darker without them?

SEARCH FOR ET

NEIL DeGRASSE TYSON: Ever wonder what the chances really are of finding a needle in a haystack? Think they're about as good as finding space aliens?

The search for intelligent life beyond Earth has been going on now for 40 years. Some folks figure, "Hey, if they haven't found it by now, it's probably not there." But as correspondent Andrea Kissick reports, compared to needle hunting, looking for alien life in all the billions of possible places out there is much, much harder.

ANDREA KISSACK: Okay, imagine you're at the beach. In order to figure out if there are fish in the ocean, you dip an empty glass into the water and look inside...no fish in the glass, well, there must be no fish in the ocean. Not too logical, is it? But that's exactly the type of reasoning that's plagued Dr. Jill Tarter for years in her long search for intelligent life in our galaxy.

Astronomers like Tarter began searching for alien intelligence about four decades ago. In that 40 years, they've only managed to search 1,000 star systems—1,000 glasses of water—while an unexplored cosmic ocean lay right in front of them.

JILL TARTER: Forty years needs to be put in the context of how big the universe is, how enormous this cosmic haystack is that we're trying to search through. And, so, we've just begun.

ANDREA KISSACK: Jill knows a little something about SETI, the search for extra-terrestrial intelligence. She's the current director of the Center for SETI Research, in Mountain View, California. Like many SETI scientists, she was drawn into the search by the early work of astronomer Frank Drake.

Drake looked at the makeup of our galaxy and created an equation to determine the likelihood that other intelligent life exists. The equation offered a simple framework for modeling the problem, taking into account things like the fraction of stars with orbiting planets, the percentage of planets that go on to develop intelligent life, and the length of time that an intelligent race lasts. The results were clear: scientifically, the odds are pretty good that we are not alone.

But if you're hunting for E.T., where do you start? What would the sign of a technically sophisticated alien culture look like?

It could look something like this.

These television and radio signals are examples of the electromagnetic waves we've been leaking into space for over 80 years. That means any planet within 80 light years of Earth is receiving them. But TV and radio are only a small part of the electromagnetic spectrum.

Although astronomers use the term "radio waves," they're generally talking about any wavelength longer than a microwave. So the radio frequency spectrum is huge, much wider than the visible light spectrum.

And signals like this are simple to generate, easily pierce dust and atmospheres, and carry well over vast distances. That's why SETI scientists believe alien cultures might be leaking them, just like we are.

In 1979, as a young graduate student, Jill Tarter joined the hunt for these telltale signals.

JILL TARTER: I was so enthralled by the idea that I lived in the first generation, ever, of human beings that could try and answer the "are we alone" question by doing an experiment, rather than just asking the priests and the philosophers what they believed.

ANDREA KISSACK: By the early 1990s, with NASA funding, Tarter was heading up the search at the largest facility in the world, the Arecibo radio telescope, in Puerto Rico. Tarter became the poster child for SETI. Even Hollywood embraced her. Tarter is generally thought to be the inspiration for Ellie Arroway, the character played by Jodi Foster in the classic science fiction movie Contact.

It seemed the golden age of SETI had arrived. Then, in 1993, Congress abruptly shut off all federal SETI funding. But that wasn't the end. Today, nearly 15 years later, something big is happening in this remote valley near Hat Creek, California. SETI's luck may be about to change.

The radio telescope dishes behind me signal the beginning of what many believe will be a SETI renaissance. And if there is to be a breakthrough, the new Allen Telescope Array is the best bet.

The reversal of SETI's fortune has largely been made possible by a $25 million grant from Paul Allen, one of the founders of Microsoft. On October 11, 2007, Allen "pushed the silver button," bringing the first 42 radio dishes on-line. When completed, the Allen Telescope Array will consist of 350 separate dishes. Together they can operate as a single "virtual" dish, over 2,700 feet across, making it one of the largest and most sensitive radio telescopes in the world. It will be the fastest tool ever built to hunt for signals of extra terrestrial intelligence.

Senior SETI astronomer Seth Shostak tells us how this new telescope will work.

SETH SHOSTAK: Well, Andrea, to understand how we're trying to find E.T., you have to understand the technique we're using, and that is to look for signals in what's called the electromagnetic spectrum. That's a lot of Greek, but all it really means for us is the radio dial. We're looking for a signal, somewhere on the radio dial, that they might be broadcasting into space. Let me show you how this works. I'll just turn that on. Okay. Now, you notice that, if I just turn the dial here, you hear static everywhere?

ANDREA KISSACK: Yeah, like white noise.

SETH SHOSTAK: That's just all natural noise. I mean, galaxies and hot gas between the galaxies, and pulsars and quasars, they all make radio noise, and it's everywhere on the dial.

But here...wait a minute...hear that squeal? And then there's the station. All that energy...it's at one spot on the dial. Nature does not make signals that are restricted to one spot on the dial, in general. It just doesn't do that.

ANDREA KISSACK: So that's intelligent life?

SETH SHOSTAK: That's intell...

ANDREA KISSACK: ...depending on your musical taste.

SETH SHOSTAK: It's definitely intelligence.

ANDREA KISSACK: Since the cosmos just don't make narrow, focused signals like this, finding one would be an almost certain sign of an alien culture.

So what is it about this new array that makes it more likely to succeed?

JILL TARTER: The Allen Telescope Array, basically, is all about speed. We can look at more than one star at once. And so, whereas, in the last decade, we looked at about a thousand stars, in the next decade, we'll look at a million.

ANDREA KISSACK: That's because the Allen Array's field of view, the area of sky it sees at one time, is much larger than any other telescope. And it can capture millions of frequencies from multiple star systems, simultaneously. Basically, the Allen Telescope Array is a SETI hot rod with SETI astronomers at the controls, 24/7.

SETH SHOSTAK: So here you can see where the rubber really meets the road for the individual antennas.

ANDREA KISSACK: Wow! That is very Flash Gordon.

SETH SHOSTAK: Indeed it is. In fact, the way this thing works...it's really dead simple. The radio waves from the sky come in, they bounce off that 20-foot diameter reflector, and then they bounce off this somewhat smaller one here, in the front of the antenna, and then they come into this feed. So this is the thing that actually collects the radio waves and turns them into electrical signals, and in fact, down the pedestal, under the ground and back to the control room.

ANDREA KISSACK: So a huge swath of the universe comes right into this room.

SETH SHOSTAK: Yeah, it does, actually. The antennas send everything they collect from the cosmos into this room. It comes in right back here. So all those data come in here, and then we put it together.

ANDREA KISSACK: So how is this different than the SETI of old?

SETH SHOSTAK: Well, the fundamental difference here is simply the amount of data you can handle, and that's just the march of technology. The first SETI experiment, back in 1960, one channel of the radio. Here we've got 100 million channels coming in.

ANDREA KISSACK: The sheer scale of the search is almost impossible to imagine. Remember, in our galaxy alone, there are about 300 billion other suns, many with orbiting planets. And beyond that, lie a hundred billion other galaxies just like our own.

Even in its current configuration, the array's virtual dish gathers nine times more information than present-day processor technology can decode. That means 90 percent of what the telescope observes is simply thrown away, at least for now. So for the next decade or two, the technology in this little room will be playing catch-up with the dishes outside.

SETH SHOSTAK: All this stuff will be replaced, in another five years, by yet faster machines, which allow us to look at more star systems, more channels, in other words: to speed up the SETI search.

ANDREA KISSACK: And as that search accelerates, Tarter and other SETI scientists are thinking about the consequences of success.

JILL TARTER: If we detect a signal, we'll do everything that we can at this site to make sure that it isn't our own technology that's fooling us or that it isn't a deliberate hoax. If we get an independent confirmation, then we will, in fact, tell the world. Because a signal isn't being sent to the Allen Telescope Array, it's being sent to the planet Earth, and the planet Earth deserves to know about it.

ANDREA KISSACK: For Jill Tarter, it's a scenario she's imagined for almost 30 years. Detecting even the accidental noise, the "dial tone" of an alien culture, would finally answer one of the most ancient questions of all.

JILL TARTER: Are we alone? Humans have been asking it forever.

The probability of success is difficult to estimate, but if we never search, the chance of success is zero.

STEM CELLS BREAKTHROUGH

NEIL DeGRASSE TYSON: What if I made fettucini Alfredo and then decided what I really wanted was cheesecake? Could I turn one into the other? Well, maybe I could. If I could turn back time and go back to the original ingredients, then I could make something else, entirely.

This idea, of turning back the clock and rebuilding something from scratch is the basic premise behind stem cell research, which aims to transform one kind of cell into another.

Correspondent Chad Cohen reports recent groundbreaking discoveries seem to be bringing them that much closer to their goal.

AMIEL REID (Sickle Cell Anemia Patient): It feels like a lot of people are stabbing me with knives, from the inside of my body, all the way down to my bone. Sometimes I couldn't catch my breath it was so intense.

STEPHANIE TERMITUS (Sickle Cell Anemia Patient): I'm in tears, basically. It's just pain everywhere, it's going through your head, your back, your legs, and you can't do anything about it.

CHAD COHEN (Correspondent): Stephanie Termitus and Amiel Reid know the inside of Children's Hospital Boston better than any teenager should. They both suffer from sickle cell anemia. Instead of the plump, doughnut-shaped blood cells most of us have delivering oxygen to our organs, their blood cells are sickle-shaped, "banana," as Stephanie likes to say. These cells can't deliver oxygen very well, which causes the kids excruciating pain. Amiel's mom is on a first-name basis with the hospital staff.

LYNNIE REID (Mother of Sickle Cell Anemia Patient): They've given Amiel pain medication, and it doesn't take the pain completely away. It sort of numbs it. I mean, that's happened, where he's ended up in the intensive care unit for four months. So it's pretty serious.

GEORGE DALEY (Children's Hospital Boston): The misshapen, stiff red blood cells get sludged and clogged into the blood vessels that feed their organs and their muscles and their bones. And this is intensely painful.

CHAD COHEN: It's been 50 years since researchers found the cause for those misshapen blood cells, a single change in a single faulty gene. Sickle cell was the first genetic disease ever identified.

GEORGE DALEY: Give me a big, deep breath.

CHAD COHEN: Yet despite decades of searching for cures, all we can do is treat the symptoms, or in rare cases, perform bone marrow transplants, which are dangerous and carry a high risk of rejection.

GEORGE DALEY: And so this is a condition that we need a new approach for.

CHAD COHEN: Lately, that new approach has involved embryonic stem cells, cells that are "pluripotent," meaning they can grow into just about any cell in the body. When they were discovered, more than a decade ago, it was thought that stem cells could fix, not just sickle cells, but the damaged cells of countless diseases: Parkinson's, diabetes, A.L.S. That's what's driven George Daley, who also heads a stem cell lab, right across the street from his patients.

GEORGE DALEY: Thinking about the potential that this has for changing the way that we not only study disease, but one day treat disease, is really very, very exciting.

CHAD COHEN: But there's a problem. Stem cells, for the most part, come from human embryos, from that time, just after sperm meets egg, when we're made up of just a few dozen cells, and the function of those cells has yet to be determined. The main sources for the embryos are I.V.F. clinics, where surplus embryos are often discarded as medical waste. Still, harvesting the stem cells destroys the embryo and for many, that's morally wrong. Others believe that holding back medical progress is also wrong.

GEORGE DALEY: Here we are, at the dawn of this whole new field, all this excitement, all this possibility, and yet we're working with one hand tied behind our back.

CHAD COHEN: But in 2007, some experiments were conducted that many believe will finally bring the fighting to an end. Japanese researcher Shinya Yamanaka figured out a way to take an ordinary skin cell from an adult, turn back its genetic clock and transform it into the equivalent of an embryonic stem cell, no embryos required. Yamanaka's motivation came when he first glimpsed human embryos under a microscope about 10 years ago.

SHINYA YAMANAKA (Gladstone Institute, University of California, San Francisco): I have two daughters. And I thought, "The differences between those small embryos and my own daughters are very small."

CHAD COHEN: The realization presented some conflict for him, since, as a physician, he believed that embryonic stem cells were his best shot at treating disease.

SHINYA YAMANAKA: To me, treating patients and saving patients is the most important thing to do. But if we can avoid the usage of human embryos, we should avoid.

CHAD COHEN: Ironically, Yamanaka had to use embryonic stem cells in order to find a way to do without them. He started by exploring one of their fundamental properties. Virtually every cell in the human body has the same D.N.A. Heart cells, liver cells, skin cells, all share the same 20,000 genes. During our development as embryos, though, different genes in different cells get switched on and off, in different ways, and that's what creates all the different types of cells in our bodies. It's called cell programming. Yamanaka believed if he could find the gene switches responsible for programming stem cells, he could flip those same switches in adult cells, like skin cells, and re-program them back to the moment before their destinies were determined.

SHINYA YAMANAKA: Each cell has at least 20,000 genes, so that means we have to find those important switches from the 20,000 candidates.

CHAD COHEN: With so many genes to choose from, so many potential combinations, the search could have been infinitely complex.

GEORGE DALEY: Yamanaka's insight was to appreciate that it was a very limited set of genes. And he set out to identify them.

CHAD COHEN: First he reduced 20,000 possible gene candidates down to 100, using on-line databases. But then, the work got harder.

SHINYA YAMANAKA: We spent, like, three years to study the function of those 100 genes.

CHAD COHEN: Were there people saying, "Give up, there's no use in this?"

SHINYA YAMANAKA: Yeah, many people told me that this is going to be very difficult. "You will fail."

CHAD COHEN: Using specially engineered mice, called knockouts, he tested each gene's ability to make pluripotent stem cells, eliminating them, one by one. After more than three years, culturing hundreds of thousands of cells, Yamanaka narrowed the gene pool down to 24 genes, and finally four. Then came the moment of truth: getting these four painstakingly selected genes to make stem cells. He took some skin cells from an adult mouse, then used a virus to insert the four genes inside them. Two weeks later the skin cells in the Petri dish had completely transformed.

SHINYA YAMANAKA: We saw cells which looked like stem cells. So it was...at the moment, you know we were very, very excited, and we were very surprised.

CHAD COHEN: Yamanaka dubbed the cells "Induced Pluripotent Stem cells," or I.P.S. cells, and found they were virtually indistinguishable from embryonic stem cells.

I can't see a difference; I wouldn't expect to be able to see a difference, but...

SHINYA YAMANAKA: No, we can't see differences either. So these embryonic stem cells and Induced Pluripotent Stem cells are indistinguishable. They are the same cells.

CHAD COHEN: It's amazing.

GEORGE DALEY: Yamanaka's experiment was bold, some might say foolhardy. I think it's the type of experiment that would be laughed out of the room in a standard peer review study section. You would never have gotten your grant funded with that experiment.

CHAD COHEN: Really?

GEORGE DALEY: And now it's probably going to win Shinya Yamanaka a Nobel Prize.

CHAD COHEN: Creating stem cells without an embryo in mice certainly made headlines in the scientific community, but less than a year later came the news that caught the world's attention. Based on Yamanaka's work, three independent scientists, James Thomson in Wisconsin, George Daley in Boston and Yamanaka, himself, transformed human skin cells into I.P.S. stem cells. It was a monumental breakthrough, and in George Daley's case, the doctor even experimented on himself.

DERMATOLOGIST: So what we're going to be doing is just obtaining a small biopsy of the skin and...

GEORGE DALEY: We have a protocol where we can have anyone walk in, roll up their sleeve...we take a very small skin biopsy, smaller than the eraser at the end of a pencil.

DERMATOLOGIST: We'll just snip this, and we're good to go.

GEORGE DALEY: Fantastic.

And those skin cells are then put right into a Petri dish, and then, within a week, all of a sudden, this huge bloom of cells appears. And then you bring into them the three or four genes that do the re-programming.

What's really remarkable is that just simply putting those genes into the cell and making them work, starts this whole process. It takes those stable, specialized skin cells and erases all the skin functions, and reactivates, enlivens the embryonic functions and turns that skin cell back into a pluripotent embryonic cell. That's really...

CHAD COHEN: Back in time, basically.

GEORGE DALEY: It's back in time, I mean, it's like a whole altered universe. I mean, it's really changed the fundamental nature of that cell.

How many times would you say you've been in the hospital your whole life?

STEPHANIE TERMITUS: I can't even say it's so many; ten times a year?

CHAD COHEN: So, how long before this technology actually helps patients like Stephanie? Well, some serious challenges will have to be overcome first.

For one thing, that virus to shovel Yamanaka's four genes into adult cells can mutate a patient's D.N.A. and cause cancer. At least one of the four genes is an actual oncogene; it definitely causes cancer. And a high percentage of the mice created with these stem cells did develop cancer. But the promise of these cells far outweighs their problems, and, as we speak, researchers around the world are figuring out how to safely use them. Late in 2007, Rudolph Jaenisch, of the Whitehead Institute at M.I.T, demonstrated a powerful application of I.P.S. cells. He used them to cure sickle cell anemia in mice. To do it, he first had to give the mice the disease.

So you were able, basically, to give the mice sickle cell disease, and use that as a model?

RUDOLPH JAENISCH (Whitehead Institute, Massachusetts Institute of Technology): Yes. These mice were highly anemic. They had just stopped growing. They were very...rather small. They wouldn't gain weight, they would die early. I mean it was...it's a very faithful model of this major human disease.

You would take then a skin cell from this mouse and re-program it to I.P.S. cells.

CHAD COHEN: Jaenisch made the stem cells using Yamanaka's same four gene switches, but this time he removed that nasty oncogene once it had done its job.

RUDOLPH JAENISCH: So now these I.P.S. cells they didn't need anymore, they didn't have that oncogene. So that was useful. And then the next thing was we repaired the genetic defect by gene targeting.

CHAD COHEN: Jaenisch targeted that single sickle cell mutation, fixed it, then prompted the stem cells to become blood cells and injected them back into the mice. Since these cells came from the very same mice, they were a perfect match; there was no chance of rejection.

RUDOLPH JAENISCH: And to our—really—delight, the blood of the mouse totally normalized, and they begin to, began to gain weight. They have lived. As far as we know, they have no problem, so that they're totally cured, these mice, from the sickle cell condition.

CHAD COHEN: So have these new stem cells made embryonic stem cells obsolete? Well, until we know for sure whether they can faithfully grow into all the different cell types, the answer is definitely no.

GEORGE DALEY: I'm not willing to concede that I.P.S. cells will ever fully replace human embryonic stem cells. The embryonic stem cell line remains the gold standard.

Could you take a big deep breath?

It has been the most exciting past few years I could imagine, in my career. And I hope that it is translated into real treatments for my kids.

AMIEL REID: My favorite subject is science.

GEORGE DALEY: That's good! That's very good. We like to hear that.

AMIEL REID: The fact that they can take your own skin and turn it into something that can cure a disease like that, it's incredible.

PROFILE: EDITH WIDDER

NEIL DeGRASSE TYSON: The bottom of the ocean is a dark and secretive place. But if you come down here to take a look around, once you turn on a light, of course, all the interesting stuff disappears.

Well, in this episode's profile, we'll meet one of the world's most determined undersea spies, who's engineering new and ingenious ways to behold the mysteries of the deep.

She's clearly a woman on the go. And when her feet are not firmly on the ground, she's perfecting her sea legs out here.

Edie Widder is a marine biologist and explorer. Her quest? To understand ocean creatures and help save their undersea world.

EDIE WIDDER: I think I have the best job in the world. Seventy-one percent of the planet is covered by water, we've explored less than five percent of the ocean, and there are so many fabulous discoveries that have yet to be made.

NEIL DeGRASSE TYSON: She's working on discovering how animals communicate using light. It's called bioluminescence.

EDIE WIDDER: They use it to attract food, to ward off predators, to attract mates. It's vital to their existence.

NEIL DeGRASSE TYSON: But there's a problem. There are only two ways to study these creatures, in their environment or in ours. Both have their limitations. Bringing them up, well, they're not exactly themselves. Going to them in a submersible also has its drawbacks.

SOeNKE JOHNSEN: It's got lights flashing, motors whirring. And then you come up to some animal, five inches away, and say, you know, "Act natural." And it's not going to happen.

NEIL DeGRASSE TYSON: So Edie came up with a new kind of camera she calls the "Eye in the Sea." It's basically a highly sensitive waterproof security camera on a timer. Its lights are red, which most underwater creatures cannot see.

To entice animals in front of the camera, Edie uses smelly fish guts inside a bait box and an electronic light show that mimics the way certain animals attract prey.

PETER GIRGUIS (Harvard University): There is no doubt that Edie is at the forefront of her field. And this is, again, sort of a tribute to her capacity as a scientist and, let's say, her closet engineering tendencies.

NEIL DeGRASSE TYSON: The Eye gets dropped off on the ocean floor, via submersible. Today, Edie is deploying it in the Bahamas.

EDIE WIDDER: So we're just looking for a nice flat piece of terrain that we can set it down on safely.

PHIL: Topside, our depth is 1,585, one, five, eight, five feet. We're going to attempt to deploy it here.

EDIE WIDDER: Now, you've got to let go at the right moment.

NEIL DeGRASSE TYSON: New revelations pop up every time Edie uses it.

EDIE WIDDER: The payoffs have been huge. I mean, every time we put this thing down, we see something nobody's ever seen before.

NEIL DeGRASSE TYSON: In the Gulf of Mexico, the Eye recorded an amazing first: a squid, over six feet long, that is so new to science, it cannot be placed in any known family.

EDIE WIDDER: I screamed so loud; and I'm not a screamer. But I was just wild. I couldn't believe it.

NEIL DeGRASSE TYSON: Most recently, the Eye revealed previously unknown feeding behavior of six-gilled sharks.

EDIE WIDDER: They were doing something nobody's ever seen before. They were rooting on the bottom and apparently sucking up, in the sand, these little pill bugs, these isopods. And it's a possible explanation for how these behemoths survive in what seems like a desert sometimes.

NEIL DeGRASSE TYSON: The Eye has allowed marine biologists to study creatures only a mother could love, or a human like Edie. She's been drawn to other species since she was a kid.

EDIE WIDDER: I loved anything to do with animals from a very early age.

NEIL DeGRASSE TYSON: School, on the other hand, wasn't quite as much fun.

EDIE WIDDER: I was so bored that I just tuned out everything that was being said.

NEIL DeGRASSE TYSON: Then Edie got a new lease on learning. Her parents, both mathematics professors, whisked her away on a magical globetrotting adventure. First stop: Europe.

EDIE WIDDER: ...went to all these magnificent art museums, and I decided I wanted to be an artist. Then we went to Egypt, and I decided I wanted to be an archeologist. And then we went to Australia and saw all of these fabulous animals, and I decided I had to be a biologist.

NEIL DeGRASSE TYSON: One of the last stops? A fateful trip to the teeming reefs in Fiji.

EDIE WIDDER: I just was mesmerized by all of this life everywhere I looked. And so I wanted to be a marine biologist.

NEIL DeGRASSE TYSON: Edie had found her element.

EDIE WIDDER: So the family joke is, "If we'd gone from west to east instead of east to west, would I have ended up as an artist?" But I think the total lack of talent might have been somewhat of a drawback.

NEIL DeGRASSE TYSON: And then she found a soul mate. She was in high school, when she caught husband Dave's eye.

DAVE SMITH (Edie Widder's Husband): There was an assembly, and I was sitting in there, and I saw her come down the aisle with some of her girlfriends. And she was wearing a leather skirt. And she just looked really hot. She was definitely fantasy stuff.

EDIE WIDDER: I think the leather skirt is a figment of his imagination. But, okay, we'll keep it in the mythology.

But he was a boy with a brain. He was the first one I'd ever met. Then one of my girlfriends pointed out to me, "Wow, he's got great shoulders." Shoulders? Really? And so we started dating. And I hate to admit it, but I married the first boy I ever dated.

NEIL DeGRASSE TYSON: And they lived happily ever after...well, almost.

EDIE WIDDER: It turns out my poor husband gets seasick if there's a heavy dew on the lawn. In fact, he has declared he will never be going to sea with me again.

NEIL DeGRASSE TYSON: That's okay. There's lots for him to do on land. Dave's an expert in high tech instruments and is pitching in with Edie's newly-founded Ocean Research & Conservation Association, ORCA.

EDIE WIDDER: You were talking about storm water runoff. You have to have that meteorological data.

A lot of what we want to do with our new organization is make people aware of the value of the ocean for our existence on this planet.

NEIL DeGRASSE TYSON: To do this, Edie came up with another invention she calls Kilroy. It's a monitoring device equipped with sensors that can track salinity, temperature, wave height, direction and speed of the current.

EDIE WIDDER: We can send out commands to it as well as receive information from it.

NEIL DeGRASSE TYSON: To send the data back to shore, Kilroy just makes a call, via standard cell phone technology. They'll keep adding sensors, including some that will measure certain pollutants.

EDIE WIDDER: And suddenly, now, we're starting to understand what's going on. So it's not just this placid blue surface that...everything looks fine. We can start telling people what's really happening.

NEIL DeGRASSE TYSON: Edie is diving into anything that will help people understand the oceans, including a children's book series on bioluminescence.

The originality of her work and her determination to share it with the public have earned her the prestigious MacArthur award.

EDIE WIDDER: I never, ever would have imagined the kind of career I've had. It just wouldn't have occurred to me that anything like this could have been possible. I didn't have any such aspirations. And I still can't believe my good fortune.

COSMIC PERSPECTIVE – SETI

NEIL DeGRASSE TYSON: And now for some final thoughts on the search for life in the universe.

I've always wondered how we would fare, if the search for intelligent life in the universe were conducted by intelligent aliens in another star system.

Suppose they used radio waves to observe us. And suppose they had super-sensitive detectors with specially designed decoders. Imagine what they would find.

If they fell within our radio bubble, that expanding sphere of waves from the dawn of our broadcast technology, then the aliens would first hear our early radio programs like Amos 'n' Andy, as these signals passed them by.

Some years later, they might decode TV programs such as The Howdy Doody Show. Then comes The Beverly Hillbillies, followed by graphic images from the Vietnam and Gulf wars.

The aliens might then look at technology markers in our atmosphere, and find high radiation areas from nuclear test blasts and global greenhouse warming from the burning of fossil fuels.

After all that, what else could the aliens possibly conclude, but that Earth shows no signs of intelligent life?

Meanwhile, with the growth of Internet radio and cable television, Earth may one day fall silent to eavesdropping aliens, with no broadcast signals for them to decode.

They might wonder if we'd disappeared completely. But, more likely, they will conclude, as do those on Earth who search elsewhere for intelligence, that the absence of evidence is not the same as the evidence of absence.

And that is the cosmic perspective.

And now, we'd like to hear your perspective on this episode of NOVA scienceNOW. Log on to our Web site and tell us what you think. You can watch any of these stories again, download audio and video podcasts, hear from experts and much more. Find us at PBS.org.

That's our show. We'll see you next time.

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PRODUCTION CREDITS

Leeches

Edited by
Steve Audette & Harlan Reiniger

Written, Produced and Directed by
Julia Cort


The Search for ET

Edited by
Stephanie Challberg

Produced and Directed by
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Stem Cells Breakthrough

Edited by
Ben Ehrlich

Produced and Directed by
Dean Irwin


Profile: Edith Widder

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Produced and Directed by
Dana Rae Warren


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Archival Material
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Edie Widder
Nikica Zaninovic, Richard Bodine, Roger Gosden, Zev Rosenwaks, Lucinda Veeck Gosden at the Center for Reproductive Medicine and Infertility
Embryology Laboratory, Weill Cornell Medical College, New York.

Special Thanks
American Museum of Natural History
Beth Israel Deaconess Medical Center
Harbor Branch Oceanographic Institute
Christy Herren
Tom Kilsdonk, SETI Institute
Kevin Langton
John Lewis
Larry Madin
Illustrator Janeen Mason
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Chris Neller, SETI Institute
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Yankee


Neil deGrasse Tyson is director of the Hayden Planetarium in the Rose Center for Earth and Space at the American Museum of Natural History.


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This material is based upon work supported by the National Science Foundation under Grant No. 0638931. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation

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