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Breaking Science: Fire ants, jealous dogs, coral clocks...

Updated Thursday, 18th December 2008

Coral rings predict tsunami, how humans affect fire ant invasions, new way to combat HIV, dog morals and does searing meat really seal in the juices?

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The team explores how the growth rings of coral suggest a major earthquake is due in the next decade; the impact humans have on fire ant invasions; why extinct bird species are not what we thought they were; how paper and double-sided sticky tape have been used to make a cheap, effective disease diagnostic device; a new way to combat chronic viral diseases and possibly cancer; how studying the 'morals' of dogs gives an insight into the evolution of co-operation.

Plus, in 'Stuff and Non-Science', does searing meat really seal in the juice?

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Chris Smith: This week how a coral clock is warning researchers that history could be about to repeat itself.

Helen Scales: The clues left behind by these corals suggests that every two centuries there's been a sequence of multiple major earthquakes. Back last year, in September 2007, there was a moment magnitude 8.4 earthquake, and researchers think this could be the start of another one of these major earthquake sequences. The chances are a big one is coming along. It will generate tsunamis that could be similar or even worse than the 2004 Boxing Day tsunami.

Chris Smith: Helen Scales, who’ll be telling us why scientists are worried, in just a moment. Also on the way how scientists have uncovered a new way to treat the monkey equivalent of AIDS.

Gordon Freeman: So Rama Amara treated the monkeys with our antibody and found that the monkeys didn’t die and their immune system made more T cells. Not only were there more T cells but these were better fighters. They were more active and made better chemicals that fight an infection.

Chris Smith: And that suggests that the same trick may also work in people infected with HIV. Gordon Freeman will be explaining how it works later in the programme. Plus, with Christmas just around the corner, we’ll be hearing how best to baste the turkey, and the answer's not, you might be surprised to know, to seal the juices in.

John Fry: The idea that searing the outside of meat sealed it and made the interior more succulent has been around for centuries, and indeed to anyone who cooks it seems so intuitively correct that it’s hard to believe it’s not true, but it is wrong.

Chris Smith: But it still tastes great which is of course the most important thing. Hello, I’m Chris Smith and this is the Naked Scientists: Up All Night, which is produced in association with the Open University.

First, let’s take a look at some of this week’s top science news stories from around the globe and bringing us up to speed this week is newshound Helen Scales. And Helen, this sounds rather scary. The coral clock says that we might be overdue for another tsunami.

Helen Scales: Yes, as we all know Christmas is coming, and who can forget the images from the Boxing Day tsunami that happened four years ago, and scientists this week have warned in the journal Science that the Indian Ocean could be due another major earthquake within the next couple of decades. Now that's according to a team of researchers led by Kerry Sieh from the California Institute of Technology in the United States, who have looked through a 700 year record of earthquake activity near West Sumatra.

Now to find this record they turned to the long stretch of coral reefs that fringe the Indonesian Island along a zone called the Sunda Megathrust. Now a bit like trees, reef building corals also lay down annual growth rings, and over time corals build up layers and layers of carbonate forming huge reefs, and by drilling into the reef you can look at those growth rings and step back in time to unveil what was going on in the environment when these ancient corals were growing.

Chris Smith: So how would we know when a tsunami had happened from that coral clock?

Helen Scales: Well, the link between the earthquakes and the corals is that when the earthquake pushes up the sea floor, and causing a relative drop in sea level, it’s likely to actually expose coral reefs. So instead of growing upwards they actually grow outwards, or they might even stop growing altogether, and of course it’s the earthquakes we know that cause the tsunamis. So the clues left behind by these corals suggest that every two centuries, for at least the past 700 years, there's been a sequence of multiple major earthquakes.

Chris Smith: So what's the chances of history repeating itself?

Helen Scales: Well, what we see is back last year in September 2007 there was a moment magnitude 8.4 earthquake, and researchers think this could be the start of another one of these major earthquake sequences, and what's particularly worrying is that two out of those three past earthquake sequences began with smaller quakes which hit before a really big one arrived. And this 2007 quake was actually much smaller than it could have been if we think about how much the forces have built up during the time that's passed since that last major event in 1833.

So the chances are a big one is coming along. We don’t quite know when it’s going to be. But, when it does arrive, the chances are it will generate tsunamis that could be similar or even worse than the 2004 Boxing Day tsunami, and that's obviously a great concern for people living in the area and makes it all the more important that proper early warning systems and evacuation plans are put together for the region.

Chris Smith: And I guess we just have to have massive respect for the awesome power of nature. We also need to have massive respect for nature when it comes to living things because how we interact with the environment can also have knock on effects for other animals, and in fact that could come round to bite us, especially if you’re a fire ant.

Helen Scales: Yes, indeed. The problem of fire ants, those nasty biting, stinging creatures, alien species that are invading parts of the world where they’re not normally found, and it turns out that the way we’re actually trying to combat those invasions might be actually missing an important point. Now this is all new stuff coming out of a study in the journal PNAS this week, by Joshua King and Walter Tschinkel from Florida State University in the US.

Now invasive species are an increasing problem around the world. They drive out native species, and they can also be a real nuisance to people, and that's definitely the case for these red fire ants in Florida. Now this particular invasive species arrived from South America on a cargo ship in the early 20th Century, and it’s a huge problem in the US and in many parts of the world. They don’t only cause these nasty bites to people, but they also cause millions and millions of dollars worth of damage to crops and livestock.

Chris Smith: So how do people try and tackle them?

Helen Scales: Well up until now it’s been assumed that the main reason these fire ants are such a big problem, it’s because the colonies are so huge and aggressive. So they tend to essentially chuck chemicals at these fire ants just to try and get rid of the infestations.

Chris Smith: But that's the wrong thing to do?

Helen Scales: But it seems now, indeed, that at least for fire ants we people are actually as much to blame for unwittingly encouraging the spread and success of these alien species.

Chris Smith: How do they prove that?

Helen Scales: Well, to find out more about this, King and Tschinkel conducted a large scale experiment in Pine Flatwoods in Florida. What they did was they took 40 by 40 metre plots, and in various different combinations, they left some of them alone, they mowed some of them twice a year and they actually ploughed some of them up once a year, and it’s that habitat change that we think has got this link to these invasive species.

Chris Smith: So what did those interventions actually do to the success or failure of the ant colonies in those areas?

Helen Scales: What they found was that in the disturbed areas the fire ants did much much better. They lived longer, the colonies grew bigger, and also the native ant species did pretty badly in these disturbed plots as well, but they did even worse when there were also fire ants present to kind of out competing them.

Chris Smith: Why would they do better in areas we’ve disturbed?

Helen Scales: It’s a good question. It’s certainly some aspect of the ecosystem that does change when we disturb the habitat. And what it really means is, and essentially, it’s all about how we control this invasive species and what we should be doing, we shouldn’t perhaps be covering them in chemicals. It’s more a case of really understanding how we’re affecting the habitat ourselves.

Chris Smith: And now Helen from ants to birds, although thankfully these ones don’t bite you possibly because they’re extinct.

Helen Scales: Unfortunately yes. These are five species of bird that were discovered living in Hawaii by James Cook’s third epic voyage, all the way back in the 1770s, but they’re now sadly extinct. But a new study of their genetics has revealed them not to be what we thought they were.

Chris Smith: How are they studying them genetically if they’re extinct?

Helen Scales: Well, that's a very good question, there are actually a few dead bodies lying around. In fact the only specimens we have left of these creatures are in museums, but they’re enough so that they could actually just extract some nuclear DNA. This was a study in the journal Current Biology this week, by Robert Fleischer, Helen James and Storrs Olson, and they’re all from the National Zoological Park at the Smithsonian Institute in Washington DC.

What they found out was that instead of belonging to a family of birds that still lives today in Australia and Papua New Guinea, it turns out that these Hawaiian honeyeaters actually make up an entirely different family. Even though they looked and behaved almost exactly the same as these distant antipodean cousins. The honeyeaters, and their name gives it away, they eat honey. They’ve got these lovely curved beaks which they go round and sipping nectar from flowers, and essentially these two different groups of birds lived in different parts of the world but figured out a really similar way of solving the problem of living in that habitat and eating that type of food.

Chris Smith: And it’s certainly an intriguing mystery, and to finish up, Helen. This is interesting, were you a fan of Blue Peter?

Helen Scales: I was indeed. I can’t say I watched …

Chris Smith: And double-sided sticky tape.

Helen Scales: Absolutely, and double-sided sticky tape and sticky-back plastic was the thing. This next story might sound like it should belong in Blue Peter but scientists have unveiled a new gadget to diagnose diseases made from nothing more than paper and double-sided sticky tape, which is fantastic.

Chris Smith: So tell us more, this presumably is a bit complicated to see in the how you do this at home section of Blue Peter but what have they done and who is it?

Helen Scales: I don’t know if it will be appearing on Blue Peter soon, but it is fantastic because they’re a really innovative new device that's extremely cheap, very simple and robust - all features that can make a huge difference in poorer countries. Now this new invention was the brainchild of Andreas Martinez, Scott Phillips and George Whitesides, all from Harvard University in the States, and they’ve published this study in the journal PNAS this week.

And the thing is that for many conditions and diseases they can be diagnosed by identifying particular substances in body fluids. Now at the moment the main option available to test for things like this are paper-based dipsticks which work by passing fluid across a flat sheet impregnated with reagents, and now they will change colour in the presence of particular molecules. But these tests are quite limited in their capabilities and in the number of different conditions that they can test for at the same time. And the secret behind these new tests is their three dimensional structure.

Now the Harvard research team used a laser to cut patterns in double-sided tape, and apparently you can actually do this at home using simple mechanical hole punches, but it would take a lot longer, and they then built up a three dimensional structure with layers of tape and paper. Now what this does is creates waterproof channels and chambers, and by dotting different types of light sensitive reagents into these chambers you can create an array of thousands of detection zones at the same time.

Chris Smith: How much do we think this will cost and is it affordable for third world countries?

Helen Scales: Well, these devices have been estimated to cost around 2p to make each, and that's really pretty good considering as well just how complex and how many different types of diseases they can actually diagnose.

Chris Smith: That is good news. How does that actually work, how does the fluid that you want to put through them actually get through them, because lots of other ‘lab on a chip’ type technologies that we’ve mentioned in the past tend to have little miniature pumps to push things around?

Helen Scales: Absolutely, this one doesn’t need a pump. It’s actually all based around just the capillary wicking forces because this is paper. You know what happens if you dip a piece of paper into water, it sucks up that water and gets all soggy, and that's exactly what's happening here. A really neat thing about this is as well is that you don’t actually need to have someone present to interpret the results. Another idea of how to apply this technology is to use camera phones. I think this is brilliant. You take a picture of the diagnostic device, once you’ve used it, and you send that off to a specialist diagnosis centre. So you don’t even have to have someone there on site.

There are also environmental monitoring applications. This could be a really easy way of testing water quality and air quality, things like that, and yeah why not use this technology anywhere that it’s needed. If it can cut costs and make things more efficient, then that's fantastic.

Chris Smith: So who knows on a future edition of Blue Peter you might find out how to build a diagnostics centre for you model of Tracy Island - thank you Helen. That was Helen Scales from the Naked Scientist with a roundup of some of this week’s top science news stories. And if you’d like to follow up on any of those items the details and the references are all on the Open University’s website and that's at open2.net/nakedscientists.

In just a moment, gr, gr, gr-een with envy, we’ll be talking to the scientist who’s shown that dogs have a jealous side, that's coming up, but first a new way to combat HIV, the virus that causes AIDS.

After it gains entry to the body HIV continuously outmanoeuvres the immune systems by mutating and changing its appearance. At the same time it also attacks the very same white blood cells that are needed to control the infection in the first place. The result is that eventually the immune system becomes exhausted and even immune cells that can attack the virus fail to respond.

Now scientists from America have tracked down a chemical signal called PD1 that seems to be responsible for shutting off the immune response, and when they block this signal, monkeys with SIV, the monkey equivalent of HIV, all remained healthy. To tell us how it works here’s Gordon Freeman.

Gordon Freeman: We wanted to come up with a new way to treat chronic diseases, and chronic diseases are really the world’s biggest unmet health need. Diseases like AIDS, hepatitis, tuberculosis, malaria, they’re all infections that start, and you just can’t kick them out. So we wanted to come up with ways to treat chronic viral diseases.

My lab has basically discovered pathways that turn on the immune system and then turn it off. When you, for instance, begin to get a cold, in your whole body there are only about 1,000 T cells that can fight that infection. Then once your body recognises it has an infection, those T cells start dividing and expanding, and the number goes up from 1,000 to ten million. Those ten million T cells are enough to really attack the disease, fight it and get rid of that cold.

Chris Smith: So what's going on when you have a chronic infection like hepatitis B or like HIV, and you don’t get rid of it?

Gordon Freeman: In a chronic viral disease like AIDS, you get that initial burst of expansion, but the body, for some reason, doesn’t successfully fight off the infection. The T cells that are unsuccessful become exhausted. These T cells aren’t good fighters anymore; they don’t make the chemicals that fight infection.

Chris Smith: But do you know why the immune system should turn off in those settings, because to turn off when you haven’t got rid of the infection is the wrong thing to do?

Gordon Freeman: I think it’s the body’s conservative response to not burning out. You can’t go top speed all the time. So the body, if it is faced with an infection that it can’t cure, the T cells fight and fight but then become exhausted and lose activity.

Chris Smith: So what you’re saying is that if you can find a way to prevent the T cells getting exhausted or prevent them turning themselves off, there's a chance that they will live to fight another day and that includes fighting off the infection.

Gordon Freeman: Not quite, what we can do is we can reverse the exhaustion. So when the T cells become exhausted, on the surface of the T cell we’ve shown they put a new molecule called PD1. PD1 receives a signal that turns off the immune response. And so the idea in this paper is basically PD1 puts a brake on the immune system, block that brake and you rev up the immune system again.

Chris Smith: So in this present study what did you actually do to try and understand what PD1 does and how blocking it can alter that?

Gordon Freeman: We’d made an antibody, a chemical that will block PD1. So what that does is it takes the brake off the immune system and allows it to accelerate again. Rama Amara infected monkeys with SIV. SIV is the AIDS counterpart for monkeys. So these monkeys get sick and after a couple of months they’re going to die.

So Rama Amara treated the monkeys with our antibody and found that the monkeys didn’t die and their immune system made more T cells. Not only were there more T cells but these were better fighters, they were more active and made better chemicals that fight an infection.

Chris Smith: And what effect did that have on the amount of virus in the bloodstream of these monkeys?

Gordon Freeman: So the amount of virus went down and the monkeys have survived eight months after treatment now. In contrast, the control monkeys all died within five months – most of them within a month or two.

Chris Smith: Now the obvious question is of course, as you’ve pointed out that SIV is the monkey equivalent of HIV, in fact we think that's partly where HIV came from in humans, so the key question is would the same trick work in a human?

Gordon Freeman: That's what we want to test. This work has progressed from the test tube to experiments with mice. Now we’re in monkeys. The next step is human studies in chronic viral diseases, and in cancer.

Chris Smith: Why would it work with cancer?

Gordon Freeman: It turns out that cancer has also stolen this idea of turning off the immune system, and they do it by making a molecule called PDO1 that engages the PD1 molecule and turns the immune system off. So cancer may be another disease, which is a chronic disease, where the immune system is shut off, and so we also think that blocking the PD1 pathway may allow immune cells to be more active and to fight cancers better also.

Chris Smith: So potentially a new way to treat a host of chronic diseases including HIV and possibly cancer. That was Harvard researcher Gordon Freeman, and he’s published that work in this week’s edition of the journal Nature.

Now from monkey business to jealous dogs, by sitting a series of dogs side by side and asking them each to hold out a paw but rewarding just one of the pair, scientists in Austria have found that dogs also seem to have a moral compass, which, the researchers say, could help us to understand how social behaviour evolved in the first place. Here’s Friederike Range.

Friederike Range: Basically, I mean there has been quite a lot of studies on primates trying to test if monkeys react to inequity in reward distribution, so if they react if they don’t get the same reward for the same task, and actually the results are quite controversial. So we were interested if other cooperating species are also able to show any of this behaviour.

Chris Smith: So this would be, for example, if you had two animals sitting side by side, and you give one of them a big bit of fruit and the other one got half a grape, the one that got half a grape would show some kind of displeasure at being deprived of the big bit of fruit.

Friederike Range: Exactly, yeah. That's what you would expect if they react to this kind of different reward distribution.

Chris Smith: And that's what you see in primates, I guess, and so is the big question then that will this translate into other animals?

Friederike Range: It’s important for cooperating. So if you’re cooperating with somebody, you should be somewhat sensitive what the outcome of the cooperation is. If the other one always gets the heap of the reward then you should pay attention to that, and you shouldn’t necessarily continue cooperating with that person because they can just take advantage of you.

Chris Smith: So would your theory be then that any social animal, dogs, wolves, monkeys, whatever, should show this behaviour?

Friederike Range: It’s likely that a lot of species that show a more complicated form of cooperation would show that behaviour, yes.

Chris Smith: So how have you set out to test that?

Friederike Range: So, we basically had two similiar dogs. We sat them next to each other, and in front of them there was a football. There's a high value reward, there’s a sausage and a low value reward, pieces of bread. And then all these dogs were, they’re trained dogs and they all knew how to give the paw.

So first, the first dog was asked to give the paw, and then it received a reward, and the second dog was asked for the paw and also received a reward. And then we rated the outcomes, so each of them got the same for giving the paw to the experimenter, and asking for the paw was repeated 30 times for each dog. And then in the second condition the partner dog receives a piece of bread and the subject doesn’t get anything for it, and what you see in those trials is that after a while they stop cooperating altogether so they just lay down and won’t give you the paw anymore even if you ask.

Chris Smith: And what happens if you do the same experiment but without the other dog present. So it doesn’t see that it's being treated unfairly compared to another dog?

Friederike Range: They continue working.

Chris Smith: So that's strong evidence that the dog is definitely reacting to the physical presence and observing the fact that the other animal is getting a reward and the dog can size up the scale of that reward relative to what it is or isn’t getting.

Friederike Range: Yes, exactly.

Chris Smith: What about in terms of food value because that's just whether or not the other dog got a reward or not, but what about if you do the experiment again but you give one dog a bit of bread and the other dog gets the preferable bit of sausage, does it realise that it’s being disadvantaged then?

Friederike Range: In general they don’t. So overall we didn’t find a significant result there. For most dogs they’d just continue working in that situation.

Chris Smith: But that's not what you see with higher animals like primates. I know some of those studies are controversial but when you do this with monkeys and things, they do seem to be able to gauge the value of the reward that they’re getting versus the other monkey.

Friederike Range: Yes but there are different possibilities why we didn’t find it. One of course is that the dogs cannot differentiate between that, and they actually have a lower sense of the feeling, whatever it is, and then also if you work for something it might increase in value, and then on top, with the dogs, we have the social reward as well, from the experimenter being then asking. So there are a lot of things that might not be so true for the primates in this experimental set up as there is with dogs.

Chris Smith: I was just going to say because if you were to go to dogs' nearest relative, the animals from which they came in the first place, wolves, they’re pack animals as well, do you think you’d see the same effect or do you think that there's this socialisation and adeptness of interaction with humans which is what makes dogs behave like this?

Friederike Range: I would be very surprised if wolves won’t show such behaviour - so we are working also with wolves. Now that we know that dogs actually can do it, we will try to use different kinds of paradigm to repeat these results and also then test it in the wolf, so that we see if this is something dog specific or is it more a general behaviour, a pattern that we’ll also find in the wolf, which I will expect.

Chris Smith: And in terms of our understanding of evolution and how animals like humans appeared on Earth in the first place and how they learnt to cooperate together, what does this new data from dogs, lower animals, actually add to that picture?

Friederike Range: I mean we know that dogs are cooperating and that other species are cooperating and this reaction to inequity might not be primate specific so it might be present in other species, thus the evolution of cooperation might get easier to explain.

Chris Smith: Friederike Range from the University of Vienna and she’s published those findings in this week’s edition of the journal PNAS.

This is the Naked Scientists: Up All Night with me Chris Smith, and time now for this week’s ‘Stuff and Non Science’ where we murder urban myths, and contemplating frying her Christmas dinner this year, here’s Diana O’Carroll.

Diana O’Carroll: This week’s ‘Stuff and Non Science’ is all about searing meat, I bet you’ve heard all those TV chefs talking about sealing in the moisture when you’re frying meat. But does it actually do that? Here’s John Fry.

John Fry: The idea that searing the outside of meat sealed it and made the interior more succulent has been around for centuries, but it was revived in its modern form around 1850 by Justus von Liebig, a German professor of chemistry and food scientist. Incidentally he founded the meat extract company that owned the well known OXO brand. So he should have known a thing or two about meat.

His idea about sealing in the meat juices was enthusiastically embraced by the famous French chef Escoffier and many others since, and indeed to anyone who cooks it seems so intuitively correct that it’s hard to believe it’s not true, but it is wrong.

Searing the outside of meat does not seal it and, in fact, in cooking tests seared meat tends to lose more moisture than unseared. Why then do we persist in searing our joints and steaks? Well the moisture content of meat is not the only factor that determines if it’s delicious and searing has some big benefits. The reactions that occur and give rise to the characteristic brown colour of seared meat also create a lot of flavour compounds that we humans like. The harder texture of the seared layer is not only attractive in its own right but makes a pleasing contract with a softer interior. In short, if you don’t sear it, meat can look uninteresting and lack flavour. So we sear to improve taste, texture and appearance but not to seal the meat.

Diana O’Carroll: That's John Fry, and he’s a food scientist and chemist. Well, if you have any myths of your own then do send them in to us. That's diana@thenakedscientists.com.

Chris Smith: So fried whole turkey might not be the best way forward this year. Thanks Diana. That's Diana O’Carroll with this week’s ‘Stuff and Non-Science’.

Well, that's it for this time; we’re back next week with another round up of the latest findings from the world of science, the Naked Scientists Up: All Night is produced in association with the Open University, and you can follow up on any of the items included in the programme via the OU website. That's at open2.net/nakedscientists.

Alternatively, you can follow the links from the Five Live Up All Night website. Production this week was by Diana O’Carroll from the nakedscientists.com, and I’m Chris Smith, until next time goodbye!

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Background

These are the sources used by the Naked Scientists in making the show:

In the news

'Experimental evidence that human impacts drive fire ant invasions and ecological change'
by Joshua R. King and Walter R. Tschinkel
in PNAS

'Earthquake Supercycles Inferred from Sea-Level Changes Recorded in the Corals of West Sumatra'
by Kerry Sieh, et al
in Science

'Three-dimensional microfluidic devices fabricated in layered paper and tape'
by Andres W. Martinez, Scott T. Phillips, and George M. Whitesides
in PNAS

'Convergent Evolution of Hawaiian and Australo-Pacific Honeyeaters from Distant Songbird Ancestors'
by Robert C. Fleischer, Helen F. James, and Storrs L. Olson
in Current Biology

Interviews

Friederike Range, 'The absence of reward induces inequity aversion in dogs', by Friederike Range, Lisa Horn, Zsofia Viranyi, and Ludwig Huber in PNAS

Gordon Freeman, 'Enhancing SIV-specific immunity in vivo by PD-1 blockade', by Vijayakumar Velu, et al in Nature

John Fry for 'Stuff and Non-Science'

 

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