Nature Podcast 7 December 2006

This is a transcript of the 07 December 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: This week researchers have tracked down a bat with an unusual trait.

Nathan Muchhala: I've discovered a species of bat which has a tongue which can extend twice as far as any other bar and further relative to its body length than any other mammal.

Chris Smith: More from Nathan Muchhala coming up shortly. Also scientists have found an off switch for brain tumours.

Angelo Vescovi: When you deliver the substance that engages the switch what you get is that the tumour slows down or even stops completely.

Chris Smith: And some good news from the field of flu.

Jane Tao: Our discovery is going to have significant impact on creating a new drug against flu infection.

Chris Smith: Hello, I'm Chris Smith, welcome to the Nature Podcast. First this week to a world record breaker, it's an animal with an incredibly long tongue, it's so long, in fact, that there simply isn't room for it in the creature's mouth, so it has to store it in its chest just in front of its heart. Here's Nathan Muchhala. Nature 444, 701–702 (7 December 2006)

Nathan Muchhala: It's a new species of bat which we discovered recently. I described this in 2005 with a couple of co-authors. And at the time we noticed that it had a longer tongue than other bats. So from there I looked more closely and I did an experiment in flight cages holding this bat for a couple of days in the field in a flight cage and training it to feed from a straw filled with nectar. And I found that it had an extraordinarily long tongue extension which is 8.5 cm.

Chris Smith: How does that compare with most normal bats?

Nathan Muchhala: Other nectar bats do have extendable tongues; the most closely related species reach about 4 cm outside of their body length.

Chris Smith: So this is a pretty formidable tongue, it's twice the normal average.

Nathan Muchhala: Yeah, it's more than twice as long as the other bats.

Chris Smith: So where does it actually put the tongue when it hasn't got it out of its mouth because that's a big tongue to accommodate, isn't it?

Nathan Muchhala: Yeah, so what I found out is that across species they hold the tongue inside of the jaw so those species with longer jaws have longer tongue extensions. What this species does is the tongue actually passes back through the neck and into the body cavity and a sleeve of tissue covers this portion of the tongue; so this follows the neck back and places the tongue between the heart and the rib cage.

Chris Smith: What does it do with such an enormous appendage?

Nathan Muchhala: Well, it uses it to be able to reach nectar which is located at the base of specialised flowers with very long flower tubes, so only this bat can reach the nectar of these flowers. So it enters a very specialised relationship where the flower benefits in that it gets pollinated by the species of bat and the bat is feeding from the flowers.

Chris Smith: So given that you said you only just discovered what the bat was, does that mean you only just discovered the flower that it pollinates too?

Nathan Muchhala: The flower was a described species, so scientists knew that it existed but they didn't know what was pollinating it.

Chris Smith: So how did you track that down?

Nathan Muchhala: Well, I captured bats with nets set out in the forest and then I collected pollen from their fur; and then in the laboratory I used a microscope to identify the grains of pollen. And pollen is pretty neat; it's really distinctive so you can identify grains of pollen to the species of flower which produced it.

Chris Smith: Where did this bat actually come by this tongue, how do you think it got to having such a formidable tongue in the first place? Has it just had a relationship with this particular plant species for all eternity or has this been a fairly recent change?

Nathan Muchhala: Well the assumption is that it must have evolved with the plant, that they must have co-evolved together, but it seems like it must have been pretty recent because closely-related bats, the bats in the same genus don't have as long a tongue extension. So it would take further study to able to date this and to actually come up with a time of the change; but it seems like it was fairly recent.

Chris Smith: But it's a pretty unusual behaviour to be able to pack your tongue into your chest isn't it?

Nathan Muchhala: Yeah, there's actually only one other species of mammal which does this, it's the Pangolin or the Scaly Anteater. These also have this sleeve of tissue, and the tongue passes back into the rib cage; these animals feed on insects, on ants, so they need a long tongue for a different reason.

Chris Smith: It's a formidable tongue indeed. Miami University's Nathan Muchhala describing his discovery of the nectar-eating bat species, the Anoura fistulata which lives on the slopes of the Andes in South America. Sticking to the head, and to the brain now and Italy's Angelo Vescovi, who's found a clever way to switch off aggressive brain tumours like glioblastoma multiformi. He adds a factor called BMP4 or bone morphogenetic factor 4 which causes the cancel cells to differentiate and become more mature so they stop behaving like a cancer. Nature 444, 687–688 (7 December 2006) ; Nature 444, 761–765 (7 December 2006) ; Nature 444, 756–760 (7 December 2006)

Angelo Vescovi: What we found in this publication is that in the cancer stem-cells, the cells that give rise to the terrible glioblastoma multiformi there is a sort of a switch which is the very same switch that is found in normal brain stem cells. And when the switch is engaged in essence it turns on a very ancient programme in the cells forcing them to stop growing and to turn into something similar to mature brain cells. As a consequence when you deliver the cell stems that engage the switch what you get it that the tumour slows down or even stops completely.

Chris Smith: So what actually is that factor that does that?

Angelo Vescovi: The factor is called the bone morphogenetic protein four, it is part of a huge family which comprises many members. We tested as many as 10 members and what we found is that a couple of the members of the family bone morphogenetic protein four and two are actually able to engage this switch which is the bone morphogenetic protein receptor, whereas the other members don't appear to do that or don't do that to the same extent.

Chris Smith: And when you actually supply that factor, what's its effect on the stem cell that it binds to, does it switch the cell off, does it kill the cell, what's the outcome?

Angelo Vescovi: This is a very good question because normally when you go about trying to stop a tumour which was our main aim you try to kill the cells; this is not what the factor does. What the factor does is it triggers internal programming in the cells so the cells will not die but they will become more mature. As a consequence when a cell of that kind becomes more mature it loses the capacity to proliferate and therefore the tumour stops. In essence the cells turn into cells that are very similar to normal brain cells.

Chris Smith: So how would you see it being used, would a surgeon go in and ablate the tumour and then the cavity left behind would be treated with this factor to erase any stem cells that remained.

Angelo Vescovi: That would probably be the first application if we can get enough data to file an investigation of a new drug. Yes, do the debulking of the tumour, so you take out the big mass, the tumour, and then you fill the cavity with probably a form containing the factor, probably with an osmotic pump pumping in the factor continuously to the block the remaining cells; that's the hope. So there are limitations as to the possibility to employ the factor for therapy because one of the main features of glioblastomas is that they spread throughout the brain; so it would be very difficult to get the factor to be spread to the same extent, but we're just at the beginning.

Chris Smith: You can't, for instance, rely on producing an agent that has the same affinity for the receptor that could be given by blood injection and which would cross the blood brain barrier and hit all the cells?

Angelo Vescovi: Which is specifically what we are trying to do right now, you asked a perfect question. The other thing that you can try to do is to couple this factor or similar molecule to antibodies that recognise the cancer stem cells. So that the protein that you create will be a chimeric protein, you will home to the specific cell to be differentiated; to become more mature.

Chris Smith: Angelo Vescovi from the University of Milan Bicocca, who's found a chemical off switch that can slow down or even stop glioblastoma multiformi by forcing the cells to take on a more mature form. I wonder if it works on teenagers.JingleNature's Podcast bringing the world of nature to life.End JingleComing up shortly a compact way to produce a high energy beam of electrons and also how monkeys linking up head to tail are teaching researchers how to design a new anti-flu drug. First though it's time to join Nature's news team for a look at some of this weeks other major science stories including nuclear weapons and global heating, which is apparently the new global warming. But first Jo Marchant caught up with Nature's business editor, Colin Macilwain who's just returned from Bonny Island in the Niger Delta where he was finding out how oil companies are trying to beat the AIDS pandemic. Nature 444, 663 (7 December 2006)

Colin Macilwain: Some of the oil companies in the Delta on Bonny Island are teaming up with experienced AIDS researchers and physicians to organize an initiative and try and deal with the potential for an AIDS pandemic outside out gates. In Nigeria as a whole about 3 million people are thought to have AIDS or HIV, that's quite a low incidence rate by African standards; but on Bonny Island it's estimated at about 8% of the adult population and it could get worse.

Jo Marchant: And what's in this for the oil and gas companies?

Colin Macilwain: Well given the difficult political situation in the Delta they need to do something for the community outside of their gates; and in order to try and stabilize that situation. They also need to safeguard their own workforce and try to avoid getting into the kind of situation of some of mining companies in Southern Africa where many of their best people are dying of AIDS.

Jo Marchant: So are you convinced then that this is really a genuine attempt to improve the situation rather than they're just doing it for the publicity?

Colin Macilwain: Well the oil companies are rather ambivalent about publicity on the project; nobody wants to have their business or their facility really associated with AIDS but they need to do something. Whether anything can be done given the massive logistical problems and the influx of people to the island remains to be seen.

Jo Marchant: Now over the Washington where the US Government announced last week that it will go ahead with developing replacement nuclear warheads even though new research suggests that its current stockpile will last for decades. Geoff can you tell us a little more about the research that's been released and about the significance of the government's decision? Nature 444, 660–661 (7 December 2006)

Geoff Brumfiel: The government has decided to go ahead with the programme called the Reliable Replacement Warhead which will look at redesigning the plutonium triggers on the current generation of nuclear warheads so that they will last longer into the future. The only problem with plan is and new research shows this week that the current warheads will last at least 100 years as is and maybe even longer.

Jo Marchant: So is this an example of politics trumping science?

Geoff Brumfiel: Yes, some people see it as an example of politics trumping science for sure. The research indicates that we have a perfectly reliable warheads and yet the government wants to go ahead with new designs. And that's seen by particularly arms control advocates as an example of the nuclear weapons complex trying to find work for itself, trying to keep itself busy. On the other hand the complex claims that the new warheads, while they may be no more reliable than the current generation will be safer and easier to maintain.

Jo Marchant: So what's likely to happen now, the decision to go ahead with a reliable replacement warhead presumably needs to go through congress; will this new research stoke opposition to the measures?

Geoff Brumfiel: I think it already has, there's been several congressmen and women out this week who've said that they're going to call for reviews of the programme and mainly they're democrats so when the democrats come into power in January they will likely hold hearings on the reliable replacement warhead and try to determine whether they really feel it's necessary. Now the RRW, the acronym it's known as, has received funding in the past but it may not next year.

Jo Marchant: Thanks Geoff'. Finally Mike, you've been talking to ecologist, James Lovelock, who was in London last week to propose that we should stop referring to the phenomenon of global warming and instead call it global heating. Why does he want to change its name, aren't there better things we could be doing to tackle climate change than worrying about terminology?

Mike Hopkin: Well, yeah, there are lots of good things we could be doing to tackle climate change but it's worth remembering that not everybody even things climate change is a problem. For everybody who's refusing to use their tumble drier there's somebody who's driving round in a 4-by-4 when they live in the city. Also it's a problem that might even extend to researchers themselves, they can often look at things in too much of a piecemeal way, so I think he viewed it as just a way to shake people's thinking up.

Jo Marchant: So presumably global heating is supposed to sound less cosy and attractive than global warming, is that what's behind this?

Mike Hopkin: I think so, he mentioned it being a wake up call. It's worth remembering that a lot of the warmest places already are where a lot of the world's people live and so it's going to cause a big displacement problem; and I think that's the prediction of the future that he subscribes to.

Jo Marchant: It's certainly true that people in a lot of countries are waking up to the seriousness of climate change; but this idea of actually changing the name of global warming, does Lovelock have much support for that idea?

Mike Hopkin: It's hard to say, I mean, he's known as a bit of a blue-sky thinker anyway on a lot of things; and his idea of the Earth resettling itself as a warmer Earth with radically fewer people all living up in the high latitudes instead of where they currently live. It's all tied up with the idea about the Gaia theory that Earth regulates itself. And obviously that theory itself was something that took decades to be accepted by the establishment, so it remains to be seen; usually he comes out with ideas and people only adopt them quite a lot later.

Jo Marchant: And will you be calling it global heating from now on?

Mike Hopkin: As opposed to 'global catastrophe of doom' or something like that?

Jo Marchant: As opposed to global warming?

Mike Hopkin: Well it's a nice idea, it probably does capture it a bit more but the thing is all the papers talk about global warming and so.

Jo Marchant: It will take a while to change that consensus.

Mike Hopkin: When searching the journals it's probably best to use the established term.

Chris Smith: Sounds like some scientists are getting hot under the collar trying to decide what to call global warming. You can find out more about those and other stories in this week's Nature; and on the web at http://www.nature.com/nature.This is Nature's Podcast from the 7th December Edition of Nature with me Chris Smith. In a second a new clue to conquering the avian flu threat. But first, how to create a beam of electrons but without needing a massive particle accelerator to do it. Jerome Faure has found that firing a laser at a gas jet creates an effect rather like the bow wave of a boat. And if you add a second laser, and fire that into the bow wave electrons can be encouraged to literally surf along it and produce a high energy particle beam. Nature 444, 688–689 (7 December 2006) ; Nature 444, 737–739 (7 December 2006)

Jerome Faure: We are trying to find new ways to accelerate particles because the particle accelerators are very large and very expensive machines; they can reach kilometers in length. So what we're trying to do is use a different way of accelerating particles in a much smaller size and for that we use lasers. And it turns out that if you use a laser and you focus it into a little gas jet in a few millimeters you can accelerate the particles to very high energies. Not as much yet as the energies from those big accelerators but we're starting to get something that's pretty similar.

Chris Smith: So when you say accelerate particles are we talking streams of ions?

Jerome Faure: Actually in this case accelerating electrons, so they're very light particles with negative charge.

Chris Smith: And how does it actually work, how do the lasers initiate that stream of electrons?

Jerome Faure: So the idea here is that you're sending a laser into a gas jet and the physics that's happening are very similar to imagining that your laser is a motor boat going onto a lake. The lake is what we call the plasma, it's ionized matter in the gas jet. And so when the motor boat is going into the lake it's creating a wave behind it in its wake. So when the laser goes into the plasma, into the gas jet, it also creates a wave and what we need to do is to get the electrons to catch the wave, to surf on the wave so that they can be accelerated.

Chris Smith: So is that why you need two lasers, one to create the wave and another to kick-start the electrons?

Jerome Faure: Exactly, that's the novelty of this work that was just published, we use a second laser just to kick the surface, to kick the electrons, to get them to ride the wave in a controlled way; and that really changed the outcome of the results.

Chris Smith: And how could you see these streams of electrons being applied, what sorts of things would be usefully served by doing this?

Jerome Faure: So there are several applications that came to our mind and one of the applications we would like to push is a medical application. We think it's possible maybe to use these electron beams to cure cancer; we're not completely sure yet but it might be an interesting application. And the other applications in different fields such as biology and certain fields of physics like solid state physics and here what we can do is use these electron beams because they're very shortened time. So they're flashes of electrons and because they're very short they give us new opportunities in this field of biology, solid state physics and even chemistry.

Chris Smith: Jerome Faure from Frances Ecole Polytechnique with a new ultra-short particle accelerator that uses two lasers to produce a high energy beam of electrons. Now finally this week to a spectre that's been hovering on the horizon for some time, and that's the threat of avian flu. Part of the problem posed the flu is that that there really are no effective drugs capable of stopping it. But now Jane Tao and her colleagues have identified an Achilles' Heel that might just provide us with a new way to hit the virus. The genetic material of flue is associated with a structure called NP or nuclear protein that's made up of repeated subunits that are linked together like beads on a string. What the team have done is to find out how these subunits lock together and now they know how that happens it might be possible to find a way to block the process and neutralize the virus. Nature advance online publication 6 December 2006

Jane Tao: We have discovered the atomic structure of the nuclear protein from the influenza A virus. We know that the influenza A virus poses serious threats to public health and we know that especially the avian H5N1 virus has spread from Asia to several other continents. So our discover is going to have a significant impact on creating a new drug against flu infection.

Chris Smith: Could you just tell us Jane what actually is the NP, the nuclear protein, how does it affect the virus and the virus's lifecycle?

Jane Tao: The nuclear protein has several important functions; the first is for it to interact with the genomic array and form the rod-shaped double-helical structure and the form of the double helical structure is important for virus infection.

Chris Smith: So if you were to zoom in with a very powerful microscope on those ribonuclear proteins, the genomic material of flu, what would he NP, this nuclear protein actually look like, how would it be formed and what would its appearance be?

Jane Tao: The protein looks like a monkey with a head and a body and a tail and we've found that the tail has a very important function because it allows the nuclear protein molecule to interact with another nuclear protein molecule. One molecule grabs the tail of the other molecule and therefore they're able to form various forms of structures like close links or very loose polymers or very rigid double helical structures.

Chris Smith: So on each piece of RNA, the genetic material of the virus, these sort of individual protein molecules link together head to tail to form a long chain or a string.

Jane Tao: Yes.

Chris Smith: So that presumably gives you a target at which to aim for perhaps making drugs which could disrupt that process and therefore be a novel kind of anti-viral?

Jane Tao: Yes, we find that the loop is pretty short, it consists of only about 20 to 30 amino acids and also this loop is very well preserved and therefore if we have a drug compound that can displace the tail loop from its binding pocket then we are able to inhibit virus replication.

Chris Smith: Do you know that will actually be the case?

Jane Tao: Yes, there are in fact another paper published a few years ago reported that if the nuclear protein is not able to polymerize, then it's not able to replicate RNA and then it's not able to produce infectious virus.

Chris Smith: Jane Tao from Rice University in Texas with the structure of the influenza virus nuclear protein. And hopefully those findings will provide scientists with clues as to how to design drugs to stop flu in its tracks. Well that's it for this week and thanks for listening. Next time I shall be hearing how some people can jump off roofs or even walk on hot coals without even flinching. Join me next time to find out how they're doing it. In the meantime if you'd like to find out a bit more about any of the reports we covered this week, they're all available on our website at http://www.nature.com/nature. And also take a look at Nature's Energy for a Cool Planet web focus which is at http://nature.com/nature/focus/energy. And if you'd like some more audio-scientific stimulation this week's Naked Scientists Podcast takes a look at the science of polonium 210 and the somewhat whiffy reaction between milk and vinegar; that's the Naked Scientists Podcast; it's freely available from the http://www.nakedscientists.com. This weeks Nature Podcast was produced by me, Chris Smith, by Anna Lacey and Derek Thorne; until next time, goodbye.

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