Nature Podcast

This is a transcript of the 14th February 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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Adam Rutherford: This week, the origin of winged mammals.

Nancy B. Simmons: What we have discovered is the most primitive known bat and it's helping us understand the earliest stages of the evolution of bats.

Adam Rutherford: And we know the 80s are back in fashion, but on this show, power dressing takes on a new meaning.

Michael Hopkin: So in the future, people could be listening to the Nature Podcast using devices powered by their by own trousers.

Adam Rutherford: Meanwhile for Valentine's Day, Kerri is off Speed Dating. But if you want to hook up, what's the best tactic.

Eli J. Finkel: If you turn to be somebody who likes everybody, the people you meet tend to like you and return, right, it turns out that is exactly wrong when it comes to romantic attraction, people can smell it on you, you kind of smack of desperation and they tend not to like you in return.

Adam Rutherford: The psychology of speed dating, coming up later. This is the Nature Podcast and I'm Adam RutherfordMusic ends

Adam Rutherford: Another jam-packed show this week, so let's crack on. Two new studies in Nature explain how some tumours become insensitive to the drugs designed to treat them. We sent Charlotte Stoddart to meet some of the researchers.

Charlotte Stoddart: The BRCA2 gene stops cells becoming cancerous by repairing damaged DNA. People with a deficient form of the gene are more likely to develop breast or ovarian cancer, but the cancer-causing fault in the gene also makes these tumours sensitive to chemotherapy drugs. Unfortunately BRCA2 tumours often become resistant to these drugs, now researchers think they know why. I am on my way to the Institute of Cancer Research in Chelsea, London to meet Chris Lord and Jorge Reis-Filho who both study BRCA2. Hi Christopher, Jorge, nice to meet you. Nature advance online publication (10 February 2008) Nature advance online publication 10 February 2008

Christopher J. Lord: Hi.

Jorge S. Reis-Filho: Hello.

Charlotte Stoddart: So, it was here at the institute that you helped to identify BRCA2, 10 or so years ago. What have you been doing since then?

Christopher J. Lord: We've come all the way from working out what BRCA2 does inside the cell and basically it's involved in a process that repairs damaged DNA to coming up with some novel therapeutic approaches for treating cancer in women that have BRCA2 mutations to testing those treatments in clinical trials but also alongside that we are trying to work out what are the ways in which drug resistance can occur for these treatments, so kind of get ahead of the game a bit.

Charlotte Stoddart: And the study published in Nature this week focuses on the development of resistance?

Christopher J. Lord: Just to put this into context, cells that have defective BRCA2 genes, the reason why they are sensitive to drugs like PARP inhibitors or carboplatin, is because they can't carry out particular form of DNA repair that fixes the damage that these drugs cause. Now what we did was we took cells and we exposed them to PARP inhibitor, we identified clones, i.e., cells that are resistant to the PARP inhibitor.

Charlotte Stoddart: So, can we go up and see the labs where some of this work took place?

Christopher J. Lord: Okay

Jorge S. Reis-Filho: Okay.

Christopher J. Lord: White coats on.

Charlotte Stoddart: So, I've got my white coat on now, and we're in one of your lab's. Jorge could you tell us a little bit more about what you did?

Jorge S. Reis-Filho: We used a cell line called CAPAN1 that has a BRCA2 mutation and treated the cells with either single high-dose of PARP inhibitors or an escalating dose of PARP inhibitors and selected clones that were resistant to the therapy. What was really interesting then was that these cells were resistant because they had to some extent reacquired the ability to repair DNA defects, in a way that it would only be possible if they had BRCA1 and BRCA2 genes that were functional.

Charlotte Stoddart: So, this secondary mutation sort of reactivated the gene in some way.

Jorge S. Reis-Filho: At that point, we did not know yet what the mechanism was? But then...

Charlotte Stoddart: Chris?

Christopher J. Lord: Well, yes we were initially mystified on the basis that it didn't at first cross our minds that BRCA2 could be functional again, so we kind of went round and round in circles, but we kept on coming back to the same place. So finally we bit the bullet and had a look to see if the BRCA2 gene had reconstituted itself, and surprise surprise, it had.

Charlotte Stoddart: And something that surprised me about your study is that the secondary mutation that sort of reactivates the gene is actually a deletion, so it means some of the gene is removed, which seems sort of counterintuitive that that could restore the function.

Christopher J. Lord: Well, you know, this I'm sure is going to be the cause of great debate, but it's true. So, the mutations that restored the BRCA2 open reading frame, the way the gene is read and then encodes. What is done is deleted out large pieces of the gene that code for what we previously thought to be, you know, vitally important regions, but actually the BRCA2 mutants that can perform this form of DNA repair are a lot smaller and lack several regions of the BRCA2 gene that we previously thought were important. But what's also interesting is, we know from work done in this lab, that when BRCA2 is absent the cells compensate by using a different form of DNA repair and that form of DNA repair is characterized by having repeats either side of regions deleted and when we looked in the cells, Alan Ashworth noted the same repeats present when finally we kind of followed up on our cell base work and looked in tumours, we saw the same thing and as closest I'll ever come as a scientist to Eureka moment, seeing those sequencing traces come back and seeing these repeats again. There was a lot of swearing and shouting and screaming and jumping up and down.

Jorge S. Reis-Filho: But the point that's really important here is that we have not only seen these in cell line models, but also in patient material and that's very important.

Charlotte Stoddart: Does this apply just to breast and ovarian cancers or to other types of cancer too?

Christopher J. Lord: No, I think it is highly likely, but lots of other forms of cancer that have a underlying genetic defect will become resistant by a similar mechanism where mutant genes are reconstituted to give you resistance to a drug.

Jorge S. Reis-Filho: And I think, not a very important implication of this piece of work, is that it does provide us, let's say, direct evidence for natural selection within tumours, given that a very small percentage of these cells may have acquired or even developed this intergenic deletions during the course of therapy. So, I think it's a very good example of Darwinian evolution in the development of resistance to specific agents.

Christopher J. Lord: As Darwin predicted, those cells that have adapted to their environment will be selected. So, you know, Darwin was right, he will be pleased

Adam Rutherford: Charlotte talking to Chris Lord and Jorge Reis-Filho at The Breakthrough Breast Cancer Research Centre at The Institute of Cancer Research in London. Now I am on my own in the pod today, Kerri is away at the AAAS meeting in Boston. We'll be hearing her report from there in the next show. But Valentine's Day is this week. So before she left Kerri went in search of love.

Kerri Smith: They say you can't hurry love, but two psychologists from North-western University in Illinois might disagree. Eli Finkel and Paul Eastwick are using speed dating to investigate how strangers become couples. They even went on a few dates themselves in the name of research. I called them to ask what they were hoping to find out by analyzing these rapid rendezvous. Eli Finkel first of all. Nature 451, 760–762 (2008)

Eli J. Finkel: We're trying to understand what makes human beings romantically interested in one another and speed dating is something of a providential gift from singles culture to social psychologists because it is a very efficient means of looking at what makes people attracted to one another and the fact that a bunch of people are all expressing their levels of romantic interest in a bunch of other people. We can find out things like "my liking for the women in the room is only moderate, but for Charlotte, in particular, is extremely high," for example. So, you can actually distinguish not only whether people are attracted to one another, but whether that attraction is unique that is specific to Charlotte, in particular or just a sort of generalized desire for the women in the room in general.

Kerri Smith: Okay and I believe it was your idea, Paul, to start using this kind of a dating scenario for research purposes?

Paul W. Eastwick: Yeah, it seems like a long time ago now, but several years ago, I was taking a graduate seminar with Eli and you know, Eli and I realized that there was still lot of great work to be done, looking at the initial attraction processes and looking at, you know, what happens after that initial meeting you have with somebody then how does a relationship grow and develop and, you know, you decide to start a real relationship with somebody or may be it just peters out. And so in this class, we decided that speed dating would be a terrific way to explore some of these early attraction processes and we took a field trip, everybody in the class went and the single people, the people who were single at the time, went speed dating and we immediately recognized that this was going to be a terrific avenue to try to explore some of these attraction processes because even though we were meeting people for very short period of time, we felt at least that there was a good possibility we were making some sophisticated evaluations and judgments about them and so we wanted to understand more about how people did that.

Kerri Smith: And so analyzing these speedy meetings allowed you to get this early phase than analyzing other types of relationship you can't get to?

Paul W. Eastwick: That's true and, you know, one thing when we started conducting our own speed dating study, you know, we took that speed dating experience and we took what we liked about it and we decided, you know, well we could study it this way and we could add to it in this dimension and one of the things that we really wanted to do was follow our participants over the days and weeks following the event because we really wanted to see, you know, what happens from here now that its been a week, what predicts were they more likely to hang out and what predicts, you know, might increasing liking for somebody over those early developing days and weeks after. You initially meet somebody and become attracted to them because the truth is we don't know a lot about that time frame, how people move from being strangers to being romantically involved with one another.

Kerri Smith: And so what have you been able to find out so far through these studies of what makes a successful date then. Eli, can I come to you?

Eli J. Finkel: Sure. There are over a 100 studies that show that women care more than men do about how much a partner makes and men care more than women do about how physically attractive the partner is, but somehow or another these studies really haven't introduced people to a living breathing partners and our data suggest that those sex differences seem to disappear once you actually meet a person. So, in other words the sex differences that people are getting when they ask participants to report on hypothetical partners may just be looking at people's theories about what they think they want and that may not map that well onto what they actually prefer.

Kerri Smith: Neither of you met your partners if you have them on a speed date, did you?

Eli J. Finkel: Neither one of us is currently dating anybody we met, when we went speed dating, but we did have a very good time and in fact we went speed dating on a Wednesday and we found out who our matches were on a Thursday and I was out on a date on a Friday and I actually dated that woman for a while, so it was excellent.

Paul W. Eastwick: I did not have the same success.

Adam Rutherford: Paul Eastwick who still can't get a date. Ending that report from Kerri. He and Eli Finkel's research is featured in an article by journalist Matt Kaplan in this week's issue. You can read that online at http://www.nature.com/nature.

Jingle

Adam Rutherford: While hopeful speed daters ask for the moon, we've still got the stars; exploding supernovae in fact, so not too romantic at all. Here's Geoff Brumfiel.

Geoff Brumfiel: Supernova are so bright that astronomers can see them go often far away galaxies, but it's much harder to tell what's happening just before a supernova explodes. In particular, astronomers have been trying to understand what causes the kind of supernova known as type Ia. In a paper in this week's Nature, two astronomers report the first evidence of what caused one type Ia supernova. I called Rasmus Voss of the Max Planck Institute for Extraterrestrial Physics in Garching to talk about what this is all. Nature 451, 802–804 (14 February 2008)

Rasmus Voss: Basically there are two different ways to create a supernovae that you have some low mass star, a white dwarf, that accretes matter from a companion star and then become massive enough that it collapses and creates a supernova in this collapse, whereas the other type, the type II supernovae that start out being a very massive star that collapses itself and forms a supernova that way.

Geoff Brumfiel: And the type that sort of steals mass from another star, the type Ia supernova, I understand that there were a couple of different theories about what might actually cause them to explode.

Rasmus Voss: Yes, the point is that we have white dwarf that has to be above a certain mass before it actually collapses and there are basically two ways to make the white dwarf more massive than this and one is that we have a normal companion star that transfers mass from the star to the white dwarf and when enough mass is transferred the white dwarf collapses. And the other model, you have two white dwarfs that because of the emission of gravitational waves spiral in and they merge and thereby become more massive than this specific mass you need.

Geoff Brumfiel: Why has it been hard to tell which theory is cracked.

Rasmus Voss: The other supernova types, we have very massive stars and they can be seen to a very large distance, so you can see this star and then it explodes as a supernova. For a white dwarf and the companion stars that they have, the systems are not very luminous and therefore you cannot see them at large distances, so it is never been possible before to see the system before it explodes.

Geoff Brumfiel: But, that's exactly what you guys were able to do, as I understand, you took a look at one of these explosions in 2007, how did you do that?

Rasmus Voss: In one of the models, the white dwarf when it accretes, it emits x-rays and there are not very many objects that are emitting luminous x-rays, so you can see them out to a quite large distance clearly on the sky. The only problem is that it is only the last 10 years that they have actually been x-ray telescopes that can do that and there are not very many supernovae that are exploding nearby enough that with these telescopes it has been possible to do it.

Geoff Brumfiel: And what did you see?

Rasmus Voss: In November there exploded this new supernovae and we looked in the archive of the galaxy and there we saw that in the x-ray images there was an x-ray source very close to where the supernovae later exploded.

Geoff Brumfiel: I guess this tells us more than just about how supernova explode, because as I understand that these supernovae are used as probes of something called dark energy, may be you can tell us what is dark energy?

Rasmus Voss: Well, no one really knows, it is basically sitting there and pushing on the universe. What it is doing is that it is modifying how quickly the universe is expanding. The type Ia supernovae, almost all explode with exactly the same luminosity and for this reason when you measure them out to very large distances, you can see at what distance did this supernova explode, so you use them to measure distances in the universe and there are some of the objects that you can measure to the highest distances with very reliable results.

Geoff Brumfiel: Now that we have some evidence for how these supernova work, how will this help us with our measurements of dark energy?

Rasmus Voss: It helps us to really know whether the supernovae are reliable as distance estimators like in the very old universe, you need to understand properly how they were formed and for this you need, for example, to distinguish between the two models for how they are formed. So, for example in one model the star that explodes has exactly the mass of this mass limits for the explosion whereas if you have two white dwarfs that are merging then the total mass that explodes as a supernova will be much larger and this can give some systematic differences in how luminous the supernovae are and if this is different at different times, then your observations when you just assume that they are all equally luminous will be wrong.

Geoff Brumfiel: So, I guess this is good news then for people studying dark energy with supernova, because it implies that the accretion model, the one that goes off with a very uniform brightness is the right one, is that right?

Rasmus Voss: Well, the problem is that this result implies this is the right one for this supernovae, there is still a very good possibility that actually both methods work.

Adam Rutherford: Rasmus Voss talking to Geoff, now with news about how you could some day be listening to the pod on an mp3 player powered by our own clothes, here is Mike Hopkin.

Michael Hopkin: Anyone who has ever used an iPod camera or mobile phone knows the frustration of the batteries running out of juice, but a new invention could soon provide a solution as well as a new definition for the term "power dressing". Researchers at Georgia Institute of Technology in Atlanta have invented fibres that can take the vibrations you make as you walk along the street and turn them into enough energy to power small electrical devices. These fibres called nanowires are made by coating strands of Kevlar with zinc oxide and they are flexible enough to be made into clothes that will really put a spark in your step, as inventor Zhong Lin Wang explains. Nature 451, 809–813 (14 February 2008)

Zhong Lin Wang: The new work we have done is using textile fibres on a surface to grow nano structures, using the nanowires we can harvest energy from your body movements, from light wind, from any kind of mechanical disturbance. Our goal is that to use those energy we generate to power little tiny devices and the future goal is power iPod and some of the sensors like gas sensors, chemical sensors, maybe UV sensors and those are our goals for general electricity and our hope is one day will change somebody's life in many ways.

Michael Hopkin: So in the future, people could be listening to the Nature podcast using devices powered by their own trousers, is that what you are saying?

Zhong Lin Wang: That's what it is. The goal is that because there are a lot of energy being wasted in our daily life because of walking, your breathing, all this body movements and can we harvest those energy for some useful purposes, especially in an environment you do not have energy supply, for example, if you work in a remote area, the soldiers in a battlefield, can we use those energy to communicate with satellite or with central command so that you can get signals back and forth. So, this is also for that kind of applications as well.

Michael Hopkin: So, say, I was wearing a shirt made out of these powered nanofibers, how much power would it potentially be able to generate and how much energy would I have to supply to make it work?

Zhong Lin Wang: The energy you can generate is that from our current calculation based on the data we received and if we have optimal design we should achieve about 20 to 18 milliwatts of power and that is the energy close enough to power a iPod, this little mp3 player and if we can improve we can power a lot of more devices.

Michael Hopkin: And that would work just with the energy supplied by walking along.

Zhong Lin Wang: Just by walking and your body movement.

Michael Hopkin: How did you actually make the fibres?

Zhong Lin Wang: The fibre was made by chemical synthesis in a beaker and is very cheap, any fibre, any shape of fibre we can grow on a surface and the growth temperature is 70 degrees C, is just your coffee temperature and using chemical solutions we grow that on a surface and no major equipment is needed for such a growth and the wires distribute on the surface of the fibre like the baby bottle brush, you know, you have a central stem and around it you have this bristles stick out that's the one we used to brush the other fibre for generation of electricity.

Jingle

Adam Rutherford: For your chance to win an iPod Touch make sure you listen to the very end of the show and remember you can write to us with any comments or feedback by e-mail. The address is mailto:podcast@nature.com. Finally, Twinkle Twinkle little bat, how I wonder where you are at! We have a new star in the world of flying mammals, a 50-million-year-old bat has been found in Wyoming. This critter is providing the researchers with clues to the early origins of bats, which amazingly make up one-fifth of living mammal species. Earlier this week I spoke to lead author Nancy Simmons from the American Museum of Natural History in New York and asked her why their find is so significant? Nature 451, 818–821 (14 February 2008)

Nancy B. Simmons: Well, let me start out and say, it's not the oldest known bat; it's tied for that record. We have early Eocene bats from actually many places around the world, however, anatomically speaking it's more primitive and that's part of it that makes it very exciting.

Adam Rutherford: So, if you say that there are many bats of this age spread across the world, does that not indicate that there is going to be a more primitive bat found at some point which is common to all of those?

Nancy B. Simmons: You can always find more and more primitive animals, the problem with fossils are particularly, relatively small fragile animals like this, is they are just not preserved very frequently and much of what we find are bits and pieces of teeth and skull from which we cannot say very much about the biology of the animals. Part of what's very unusual about the circumstances with the find of this animal is that it comes from a rock formation which was formed in ancient fossil lake where very very fine grain sediments preserved beautifully whatever was on the bottom of the lake at that time. So, there is a lot of beautiful fossil fish come from these deposits and very rarely an animal like a fossil bat, which apparently somehow fell or washed into the lake and was preserved beautifully and so that's part of it. What's very exciting here is we have in essence the complete skeleton of this animal to work with.

Adam Rutherford: Looking at the figure in the paper, it is an excellently preserved skeleton. Tell us about the ear morphology because that indicates something very specific about bat evolution, doesn't it?

Nancy B. Simmons: Yes, there are many different morphologies in the skull region of the animals and we can tell a lot about what an animal's sensory habits were by looking at the morphology of the bony part of the base of the skull. Within bats we see two different morphologies, so echolocating bats have larger cochlea than other mammals and also then non-echolocating bats. Not all bats use echolocation, Old World fruit bats use vision instead and they are not capable of this sophisticated echolocation that we see in all other bats. Interestingly all of the previously known Eocene bat fossils, where we had fossils that were preserved well enough to look at these features, all showed that they were probably echolocating animals. This new bat that we are describing, we've looked that the ear region is fairly nicely preserved in one of the specimens and it lacks all three of these features, so we believe that the new bat was not an echolocating bat.

Adam Rutherford: So the absence of echolocation in your new specimen, what does that tell us about the order in which flight echolocation has occurred?

Nancy B. Simmons: Well, the fact that the new animal was clearly capable of powered flight yet did not echolocate is a really interesting combination. In order to understand what this means we need to put it into a phylogenetic context, that is we need to think about how this animal is related to other bats and we did an analysis based on many many features of the morphology of the new bat that seems to come out right at the bottom of the bat family tree. So, what this seems to tell us is that flight evolved first and that echolocation was something that evolved a little higher up the bat family tree and then was shared by all of the subsequent descendants. Now among living bats there is one lineage, the Old World fruit bats that don't use echolocation but that lineage is nested so far up within bats that we now believe that they must have lost the power of echolocation because many of the branches below them on the tree shared echolocation with all of the living bats. So, today our hypothesis is that flight evolved first followed by echolocation and then subsequently much further up the tree echolocation was lost in this one lineage that led to the Old World fruit bats.

Adam Rutherford: Nancy Simmons from the American Museum of Natural History. Our sound of science is in tribute to Roy Scheider who died this week best known for playing Chief Brody in the blockbuster, Jaws. Jeff Drazen, Max Cremer, Craig Smith, and Eric Vetter at the University of Hawaii were investigating underwater canyons by submarine, when they were stunned to find a humongous specimen of Hexanchus griseus, the six-gill shark, taking their bait. This is what real marine scientists sound like when they see a genuine leviathan of the deep. I'm Adam Rutherford and these guys are definitely going to need a bigger boat.

[Sound of Science]

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Adam Rutherford: If you're still listening, here's your chance to win an iPod Touch courtesy of the Nature podcast.

Kerri Smith: First you need to listen to the following three sounds of science taken from the podcast archives from autumn last year and then go to our web site that is http://www.nature.com/nature/podcast and follow the link at the very bottom of that page. Here they come.

[Music plays with three different sounds]

Adam Rutherford: So identify those three sounds and follow the link from http://www.nature.com/nature/podcast. This competition closes on the 31st of March 2008. Good luck and thanks for listening.