Nature Podcast 30 November 2006

This is a transcript of the 30 November edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (http://www.nature.com/nature/podcast), which also contains details on how to subscribe to the Nature Podcast for FREE, and has troubleshooting top-tips. Send us your feedback to mailto:podcast@nature.com

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Chris Smith: In this weeks program there's a bitter aftertaste for some red wine producers.

Roger Corder: Everybody thinks that having a glass of wine is going to reduce their risk of heart disease. The studies published in our paper suggests it may not be as simple as that.

Chris Smith: Roger Corder joins us shortly to tell you what vintages you need to put on your Christmas list. Also, the sound of music – how researchers have solved the mystery of why the Stradivarius violin sounds so sweet.

Joseph Nagyvary: We found the wood of Stradivari and Guarneri had been brutally treated, chemically, possibly for the purpose of wood preservation but we think it has a magical effect on the sound of those violins.

Chris Smith: And a 2,000-year-old-machine discovered on the seabed yields the secrets of its workings.

Joseph Nagyvary: An ancient technological device, what we believe is an astronomical calculator that dates from about 100BC, maybe just a little bit before that. It was originally found in a shipwreck in 1900 by some sponge divers who got blown off course in a storm.

Chris Smith: That's the Antikythera, which was an ancient celestial calculating machine; there'll be more about its history and how it came to be made, coming up very shortly. First, though, with the festive season approaching, what will be in your Christmas wine hamper this year? Well, hopefully something made in Sardinia or France because Roger Corder thinks he's got to the bottom of the so-called French Paradox or the Mediterranean diet, the fact that people around the Mediterranean seem to live a lot longer than the rest of us. It turns out that certain red wines contain very high levels of chemicals called procyanadins. These block the production, in the endothelial linings of blood vessels, of a substance known as endothelin-1 which is linked to heart disease and the good news is that, unlike some other wine anti-oxidants, like resveratrol, which are only found in tiny amounts, there's more than enough procyanadin in the average glass of the red stuff to keep your arteries in tip-top condition. Nature 444, 566 (30 November 2006)

Roger Corder: A few years ago we started looking into whether or not red wine could regulate endothelial function and we published, in 2001, evidence that you could suppress endothelial synthesis, which is a key mediator involved in heart disease, with extracts of red wine. And what we found in that study is that the degree of activity of each wine correlated with its polyphenol content but we didn't know precisely which polyphenol was involved, so over the past few years we've been purifying polyphenols from wine and identifying them just to see what they are.

Chris Smith: So what actually are the polyphenols and how do you think they work?

Roger Corder: Difficult question. What are the polyphenols? The polyphenols we identified to have the most vascular activity in wine are called procyanadin. How do they work? That's a question we will need to answer in the next series of investigations, it certainly doesn't look like they act as anti-oxidants – they somehow are triggering a change in endothelial cell function that clearly is very protective.

Chris Smith: But how did you track down what was in wine that was important in this process?

Roger Corder: We used endothelial cells in culture, we looked for response, which was suppression of endothelial synthesis, and we purified activities from wine based on the fractions that had the highest inhibitory activity and we eventually got some pure polyphenols and by mass-spectrometry in Glasgow the identities of these polyphenols were shown to be procyanadin. Beyond showing procyanadins, an important observation from our work is that wines coming from areas with high longevity, in Sardinia and in South West France, are much richer in procyanadin, suggesting an actual link between the levels of procyanadins in wine and the degree of protection that's afforded to a consumer of these wines.

Chris Smith: And why are those wines from those particular regions so much richer?

Roger Corder: Well I think there's two different explanations. One is that in Sardinia, the wines are from grapes grown at higher altitude and we know that UV light can affect polyphenols synthesis in grapes and in South West France it's the use of the particular type of grape, the tannat grape which is grown mainly in this South West region around the Departement of Gers and so having a wine that can be up to ten times more active in terms of biological property than a modern New World wine.

Chris Smith: But if you actually look at how much of these agents are present in the average glass of wine, is it enough to have a physiologically beneficial effect?

Roger Corder: Well that's where we certainly differ from the studies where resveratrol, for instance, has been attributed as the explanation for the French paradox, but you would have to drink hundreds of litres of wine per day to get that benefit from resveratrol. In the case of procyanadins, you can have up to a gram per litre which is a thousand times more than the typical levels of resveratrol and you would only need to have a small percentage of that absorbed from an average glass of wine to actually get to the levels in blood that you would expect to have these effects on endothelial function.

Chris Smith: So these very popular New World wines, which are lacking in this particular factor, are not really as good for us as people might have us believe then?

Roger Corder: Absolutely, I think we have to reappraise the whole idea that red wine consumption is universally good for you because on the basis of our research you would conclude that only some wines are going to confer that benefit and many other wines will confer little more benefit than drinking white wine.

Chris Smith: I rather regret splashing out on that crate of Australian Shiraz now. That was Roger Corder from Barts' in the London Medical School, he has found that some red wines are better for you than others, and it's all down to how much procyanadin they contain. And now let's raise a glass to Joseph Nagyvary who's discovered that the success in the 17th and 18th century, of the world's most famous instrument makers, Antonio Stradivari and Andrea Guarneri, could all be down to a fluke of chemistry. Wood shavings from a surviving 4 million dollar Stradivarius violin have shown that the wood has been chemically brutalised, possibly using iron salts. But Nogavari doesn't think it was done to make the sound sweet, that turned out to be a convenient side effect, it was actually intended to act as a form of preservative. Nature 444, 565 (30 November 2006)

Joseph Nagyvary: We set out to answer the question whether Stradivari and Guarneri use any kind of magic potion for improving the acoustical properties of their musical instruments. So we gathered samples from authentic instruments, we also used, for comparison, an old English instrument and an old French instrument. And then we analysed for changes in the three major components of the wood. The wood is always made up of cellulose, lignin and hemicellulose.

Chris Smith: Who actually gave you their instruments, because these things are pretty valuable, aren't they?

Joseph Nagyvary: I'm really not supposed to divulge the answer to this question. All I can say that samples came from one of the best-known restorers of antique instruments.

Chris Smith: So this was in the course of actually doing a bit of work on the instrument, you were able to get some shavings or something?

Joseph Nagyvary: Exactly, so it's a routine operation of repairing cracks, you excavate 70% of the wood and we got these shavings.

Chris Smith: And when you analysed them, what was the actual findings?

Joseph Nagyvary: Well the actual finding is really shocking, that we see major destruction of two components of the wood. The hemicellulose is greatly damaged and also the lignin component is greatly reduced.

Chris Smith: So what sorts of things would have provoked those kind of chemical changes in the Stradivarius and the Guarneri instruments?

Joseph Nagyvary: We tried, first, just doing boiling of specimens and baking. That is not drastic enough so my explanation and this is still just an educated guess, we see the action of oxidising agents so they included in their solution and probably they heated the samples of wood, including some sort of oxidising minerals. You know, the choices are very limited when it comes to ancient oxidising agents. Iron salts would be the most likely candidates. Iron and copper.

Chris Smith: And the idea behind exposing the wood would have been to alter its chemical properties and therefore its acoustic properties too, presumably?

Joseph Nagyvary: Well, I am a heretic in this regard. I really don't think that Stradivari and Guarneri did this for acoustical purpose. I think that was a rather routine process, around that time, in Cremona where most woodworkers had to preserve their wood against the woodworm.

Chris Smith: So it was almost discovered by accident then, in an attempt to get rid of the woodworm, they actually managed to make the wood sound a lot nicer?

Joseph Nagyvary: Well, my explanation is actually the Italian method of violin making was lost because I assume that the violin makers like Stradivari and colleagues really did not fully appreciate the effect of the preservatives and later on they used different preservatives and different techniques and so no-one really knew what makes the sound so pure.

Chris Smith: Joseph Nagyvary, who is Professor Emeritus at Texas A&M University. Coming up shortly we'll be finding out why plants are not so green when it comes to their knowledge of economics, but first Jo Marchant delves inside the workings of a 2,000 year-old-mystery, the purpose of an incredibly advanced mechanism, discovered in a shipwreck. Nature 444, 534–538 (30 November 2006) ;Nature 444, 551–552 (30 November 2006) ;Nature 444, 587–591 (30 November 2006)

Michael Wright: This a unique device, nothing like a device of this complication is known for a thousand years afterwards, till you get to the medieval cathedral clocks.

Mike Edmunds: I can't tell you who made it, but I can tell you what sort of man made it, the man who made it was a highly skilled mechanic, he knew exactly what he was doing.

Xenophon Moussas: This Antikythera mechanism has been my obsession since the time I was a child.

Jo Marchant: This is a sound that hasn't been heard for 2,000 years, it's a reconstruction of the Antikythera machine, the most sophisticated technology we know about, from its time and for many centuries that followed. Discovered in 1900 in a 1st century BC shipwreck near the Greek islands that bears it's name, the remains of a complicated of gear wheels and pointers was so battered and corroded it has taken decades for researchers to work out what it was for. But it's clear that is far more complex than any other device we have from Ancient Greece. So what was this thing and who on Earth could have made it? This week a study using modern technology to image the fragile pieces is published in Nature and it gives us the clearest picture yet of how the machine worked. I jumped on a plane to Athens to meet physicist Xenophon Moussas one of the paper's authors. He took me to see what remains of the mechanism on display in the National Archaeological Museum. The fragments look incredibly, they're flaky and green and covered in these corrosion products but you can see the tiny little markings on it and all the little gear wheels fitting together and how sophisticated was this mechanism?

Xenophon Moussas: It is not only a very sophisticated mechanism, it is the oldest instrument that has scales on it. We see the largest fragments, these are free, we can clearly see a large gear wheel which drives all the mechanism and in this and the other fragments we can count something like thirty gears which help the astronomers of the 2nd century BC, we believe now, to calculate the positions of the Sun, the Moon, perhaps to work out the time of eclipses of the Moon and possibly of the Sun as well. Since we discovered inside the mechanism very many hidden writings which are the manual of this ancient computer, we know for sure that many parts of the text are referred to the motion of the planets.

Jo Marchant: So these crumbly green fragments once worked like a calendar to calculate the motions of the Sun, Moon and maybe the planets in the sky and to predict future astronomical phenomena such as eclipses. I'm intrigued to know what the device would have looked like before it spent 2,000 years at the bottom of the sea so on my way home from the airport I go to see Michael Wright who is curator at the Science Museum in London for 20 years and who has devoted much of his life to building a model of the mechanism. So we've got a wooden casing, basically a little bit smaller than a shoebox with a metal plate with some dials on the front, could you just turn the knob for me and explain what's happening as it goes around?

Michael Wright: With pleasure, when I turn the knob, the gear mechanism inside is driving this set of pointers showing the movement of the Sun and the Moon around the zodiac. This little rolling ball at the centre which shows the phase of the Moon, as the sun and the Moon pointers move relative to one another. I've also built into this the motions of the five planets that were known in antiquity, Mercury, Venus, Mars, Jupiter and Saturn.

Jo Marchant: Who do you imagine made this and why?

Michael Wright: I can't tell you who made it but I can tell you what sort of man made it. I can tell you, from having examined the original, that the man who made it was a highly-skilled mechanic; he knew exactly what he was doing. The other thing I can tell you about it is that the man who designed it certainly knew his astronomy. We have, from antiquity, just the names of a couple of people who are said to have been responsible for such gadgets, one of them is Archimedes, an instrument like this is said to have been taken when Syracuse was captured in 212BC, the time when poor old Archimedes was killed. The other name we know is Posidonius, who worked in Rhodes in the 1st century BC who is said to have designed some sort of an instrument showing the motion of the planets.

Jo Marchant: The ship on which the Antikythera Mechanism was found, had just passed Rhodes when it sank, probably on it's way to Rome and may well have stopped off at the island. Mike Edmunds, lead author of a study in Nature also speculates that Posidonius or even his mentor, Hipparcos, arguably the greatest of the greatest of the ancient Greek astronomers, might have had a hand in constructing the mechanism. I went to see him at Cardiff University to ask how his team's results link the device to Hipparcos?

Mike Edmunds: Our study really hoped to get some really good, modern investigation of the mechanism using very modern imaging techniques and complete X-ray tomography, basically you give it a good old body scan. We believe we've managed to show that the way in which it displayed the moon is very, very advanced and seems to be based on a theory of the moon developed by Hipparcos around about 150BC.

Jo Marchant: So do you think that Hipparcos might have had something to do with building this mechanism?

Mike Edmunds: Well, its very tempting to think so, we haven't actually found his fingerprints or Hiparcus made this on the mechanism but whoever did build this was extremely intelligent, it's just beautifully designed, I think that's one of the most surprising things that comes up of this, is realising how sophisticated the design is, so there's a great mind behind it.

Jo Marchant: So it sounds like, in terms of the astronomical knowledge, this fits in with what we think was known during that period, but what about the technological sophistication, how does that fit in?

Mike Edmunds: That's a very interesting question. This is a unique device, it shows the ability to think through and manufacture a highly technical device, it's certainly something you couldn't make one of, it would have to be part of a series of these things, made over a period of time. So it does suggest there could have been real technological capability that could have done other things as well but we have no real knowledge of anything this technological being produced at that time. Maybe it's there, maybe it's been lost. One of the fascinating things would be whether that this work will, in fact, root out other examples of this sort of technology.

Chris Smith: Nature's Jo Marchant exploring the Antikythera and where it came from and now to the world of metamaterials which are substances specifically designed to respond to certain frequencies of electromagnetic waves. At the moment computers work at giga hertz frequencies but wouldn't it be nice to make them work a thousand times faster - at the terahertz rate? Well the reason they currently don't is because materials capable of doing this don't crop up naturally which has made it difficult to exploit this part of the electromagnetic spectrum. But now Richard Averitt and his colleagues have developed a material that can work within the terahertz regime. Nature 444, 560–561 (30 November 2006) Nature 444, 597–600 (30 November 2006)

Richard Averitt: There's this field of metamaterials where people really make artificial structures that have functionality that, maybe, doesn't occur naturally but those materials that they've made, what we've done is made them active, we've made them be able to do something that you couldn't otherwise do and so a simple example of that is what's just like a solenoid. So you can imagine that if you have currents flowing through this solenoid then you get a magnetic field and so you get these interesting responses. What we've been able to do is being able to just apply a simple voltage and shut off that solenoid, so that's just a very simple way to control the properties of this material. And then the question becomes at what frequencies are we doing this? And so the way to look at that is, while working in the so-called terahertz regime and to give you an idea of what a terahertz is, you know, most computers these days work at about a gigahertz and so the terahertz regime is three orders of magnitude faster than that, so we're working at about 1,000 gigahertz.

Chris Smith: And why is that actually useful Richard?

Richard Averitt: It's useful because in this part of the electromagnetic spectrum there's a dearth of devices to manipulate this radiation at these frequencies so this material that we've developed, basically, allows us to switch the radiation on and off so we can change the transmission properties of a material just by applying a voltage at this frequency range and no-one has been able to do that before.

Chris Smith: And turning now to Willie Padilla, who is one of the other researchers on the paper, Willy, what are the implications now that you've arrived at this point? How can you see this being pushed into operation actually on the grand scale?

Willie Padilla: This is already applicable to devices within the terahertz regime. The uniqueness of what we've fabricated and demonstrated is that this metamaterial device or artificial device can be used right now within the terahertz regime. The reason being that the terahertz regime is the last undiscovered portion of the electromagnetic spectrum and so even though this is a first-generation device, it can be used already. And so one example of what it could be used for would be high bit rate communications at terahertz frequencies. What we've demonstrated is a switching of terahertz radiation.

Chris Smith: Why has it taken so long for us to be able to venture into this electromagnetic territory? Why couldn't we do this before?

Willie Padilla: The terahertz regime of the electro magnetic spectrum is actually a universal gap in the electromagnetic spectrum. It happens to lie between two regimes in which there has been considerably more work such as the microwave, which is at lower frequencies, and the infrared regime, which is at higher frequencies, and it's really the region between a optical response, at higher frequencies and an electronic response at lower frequencies. So its so happens that the Universe is constructed such that materials naturally do not respond here. And so what metamaterials allow us to do it to, instead of being stuck with natural materials, as they occur and as we find them, we can construct an artificial material to have a designed response, so we can design a material to have an exact electromagnetic response at terahertz frequencies. And it's really a new design paradigm that permits the construction of devices to be operable within this range.

Chris Smith: Introducing a newmeta material, capable of supporting terahertz frequencies, that was Willy Perdillo from Boston College and before him Richard Averitt from Los Alamos National Laboratory. Now to finish this week, we are taking a leaf out of the plants guide to economics to find out how the forest can teach us a thing or two about the marketplace. Jo Marchant spoke with Science writer John Whitfield. http://www.inthebeatofaheart.com

John Whitfield: In a sense the living world is the most, the most cutthroat market that there is in the if you don't make a profit then you go out of business, you go extinct. Whether you thrive or go bush depends on your investment strategy, how you get resources and then what you do with them. That's true for life in general and it's no less true for leaves, so, for example, a plant has a decision about what sort of leaves it makes and if you go into woodland you can see all these different decisions, there might be something like, say, holly which has very tough, shiny, long-lived leaves, or there might be things like oak and beach which have softer, flimsier leaves which last for a few months and then they're thrown away at the end of the summer. It's a bit like when you go shopping for clothes, for example, you can decide if you are going to spend all your money on buying one suit that's very well made and is expensive and is going to last you a long time or you can spend it on lots of t-shirts which might fall apart quickly but each one is cheap.

Jo Marchant: And I understand that these kinds of factors are constraining the kinds of leaves that you can get?

John Whitfield: That's right. So if you look at the about 250,000 species of plant that there are, you see everything from flimsy grass blades to palm fronds, say, that you might be able to cut yourself on, they are so hard and tough. Things like dessert plants that have very small, tough leaves, but what a bunch of ecologists discovered a couple of years ago is that if you look at the sort of variation that you find in leaves, in the type of things that plants invest in, so say how thick a leaf is, how long it lives, which is largely as consequence of that physical toughness, how quickly it photosynthesises, which is related to things like how much nitrogen you put in it. then all the world's leaves line up on this one spectrum, they call it the World Leaf Economics Spectrum and that explains nearly all the variation in all these different types of leaves properties and it shows that although there's this mind blowing diversity of plant form and leaf form out there, it actually seems as if the physics of economics, if you like, the options that plants have in investing their resources, is actually quite constrained and so what choice the plant really has is where to put itself on this line that runs from short-lived, fast-return, flimsy leaves to very tough, long lived but slowly photosynthesising leaves?

Jo Marchant: So why are ecologists and botanists so excited about this whole concept, how is it going to help their fields?

John Whitfield: Well partly it's just kind of cool that so much of the variation in the natural world can be explained by this one set of properties, about plants, so that kind of makes the world a lot simpler for scientists studying it because you don't have to understand a lot about every individual plant in detail, you can measure a few things and get a good idea about how it will live and how it will fit into the living world and in a biological sense, leaves are the foundation of the living world, in a way, because at least on the land that's where energy comes into life, there at the bottom of the food chain.

Jo Marchant: So you discuss some of these concepts further in your new book, In the Beat of a Heart, can you just tell a little bit more about that?

John Whitfield: That's right. So in general its about the idea that although the living world is very complex and very diverse, there are patterns like this that underlie it and, in some sense, are a bit like the laws of physics and can be explained in a physics-type way. The subtitle of my book is Life, Energy and the Unity of Nature and if you understand what living things do to get energy and then what they do with it, you can understand the patterns in nature.

Chris Smith: Science writer John Whitfield, who has written a feature this week exploring the economics of leaves. You can find out more about his new book via his website which is http://www.inthebeatofaheart.com. Well, that's it for this week and thanks for listening. Do join me next time when we'll be finding out how to do battle with brain tumours, in the meantime don't forget that all of the reports featured in this week's show are also available on our website at http://www.nature.com/nature. For more scientific stimulation in the interim, this week's edition of the Naked Scientists podcast explores the science of brain repair, including how scientists are using stem cells to overcome the problems of paralysis caused by spinal chord injuries and blindness secondary to retinal damage, that's the Naked Scientists podcast which is freely available from http://www.nakedscientists.com. The Nature Podcast, this week, was produced at Cambridge University by me, Chris Smith with Anna Lacey and Derek Thorne. Until next time, goodbye.

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