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Beaking Science: Fish elections, cholera, evolution...

Updated Friday, 14th November 2008

Identifying faulty genes, what stickleback leader selection says about us, and predicting cholera outbreaks from space.

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The team explores how combining technologies has enabled the identification of the gene faults linked to cancer, how injections into the groin lymph nodes is a more effective way to treat allergies, why we now have a better view of another solar system, how sticklebacks select a leader, how cholera outbreaks can be predicted from space, and why a specimen of Homo erectus sheds light on our evolution.

Plus, in 'Stuff and Non-Science', are silencers really as effective as Hollywood would have us believe?

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Chris Smith: Hello and welcome to the Naked Scientists: Up All Night which is produced in association with the Open University. I'm Chris Smith. In this week’s show, why scientists might have to rewrite the history books of human origins because our ancient relatives, it turns out, might not have looked the way that we first thought they did.

Scott Simpson: So the expectation was that Homo erectus would be a very narrow hipped individual, a very tall individual like we see in modern Kenya and Tanzania and Ethiopia. But in fact what we’re finding is that our individual sort of turns that on its head because we've got a very short individual, much shorter than previously known for Homo erectus, and with a very, very wide pelvis, much wider than we see in any living modern population.

Chris Smith: Scott Simpson, and what that big pelvis meant was that our ancient ancestors could begin to have babies with much bigger brains. Poor them I hear some of you say. And as Bond mania takes hold of cinemas across the World, we'll also be unpicking the workings of the silencer to find out whether they really can do what Hollywood would have you believe.

Hugh Hunt: When the bullet leaves the end of the barrel, the pressurised gas suddenly expands, and that’s what makes the noise. And it's just like it with a balloon. If I take a balloon, I’ve got a balloon here, and if I pop it, it sounds like this [balloon pops]. Okay. It makes a big noise because the gas inside the balloon is suddenly being released.

Chris Smith: Hugh Hunt will be investigating the workings of the assassin’s silencer. That’s all on the way in this week’s Naked Scientists: Up All Night. First, let’s take a look at some of this week’s top science news stories from around the World, and pouncing on the pick of this week’s scientific catch, here’s Kat Arney. Kat, I hear there’s been a breakthrough in the genetics of cancer?

Kat Arney: Yes. Well according to tabloid newspapers cancer’s caused by anything from toothpaste to telegraph poles, but in fact cancer is due to gene faults. And writing in the journal Cell this week scientists have used a combination of new technologies to find thirteen new genes that are involved in liver cancer, and twelve of these had never been linked to cancer before, so this is really quite good stuff. And the genes are all tumour-suppressors, which means they normally act as brakes on cell division, and if they’re faulty, then the cells multiply out of control and this can lead to cancer.

Chris Smith: How did the researchers detect these new genes?

Kat Arney: Well, the problem with looking for this kind of gene faults in cancers is that basically cancer cells, genetically speaking, are a total mess. They’ve got all sorts of faults in them, and it's really difficult to try and work out what are the important ones against what’s just the background noise. And so in this study the researchers first identified genes that kind of cropped up again and again and again as being faulty or missing in around a hundred human liver cancer samples, and the idea was that these missing genes were likely to be tumour-suppressors, and that turned up three hundred and sixty-two potentially interesting genes.

So then they identified mouse-versions of three hundred and one of these human genes and used a technique called RNA interference to silence those one at a time in liver cells. And then they put these modified liver cells back into mice. And the mice they studied already had genetic changes that predisposed them to developing liver cancer, but on their own those weren't enough to give them the disease, and the idea was to see which of the genes lost in the human cancers could push those mouse cells over the edge into developing cancer.

Chris Smith: And what was the outcome?

Kat Arney: Well, this approach turned up thirteen genes that actually led to cancer when they were faulty, out of the original three hundred, so this is pretty much needle in a hay stack stuff. So this of course could pave the way for new treatments for liver cancer, which does have a relatively low survival rate, because if you could find a way to reactivate or replace the missing tumour-suppressors, then you may be able to stop the disease.

Chris Smith: Do they also have any sort of what’s called prognostic value in terms of you could test to see if someone carries some of these altered genes and that will give you a clue as to what their risks of developing a liver cancer are?

Kat Arney: Well, yes, that’s the kind of idea. It may be not so much for working out if someone’s at risk of liver cancer but certainly the way that medicine for cancer is going is working out what your tumour looks like, genetically speaking, and then how you would tailor treatment to it. So it's probably got a lot of benefits in terms of working out how people are going to do with the disease and what sort of treatment they should have.

Chris Smith: Now here’s a story not to be sniffed at, which is a better way to tackle allergy by giving people injections with the thing they react to and it desensitises them.

Kat Arney: Yes. Do you have hay fever?

Chris Smith: Yes, I do, and I have had a series of injections when I was little, and they had a modest benefit, but I don’t think I took them for long enough.

Kat Arney: Yes, I get hay fever and I just take tablets and snuffle for most of the year. But yes, as you said, people who have very severe hay fever can have a series of injections, and you’re directly injecting them with the thing that they’re allergic to so pollen or particles from the air. And that’s because hay fever is caused by your body just mounting an excessive immune response to the allergens in the air, the pollen and that kind of thing.

Chris Smith: So why would injecting someone with the very thing they’re reacting to help to make them better?

Kat Arney: Well it basically helps the immune system to learn that this stuff is okay. But it does carry quite a big risk. Because obviously the person is allergic to this and it can cause very severe allergic reactions, this stuff called anaphylactic shock, which can be extremely dangerous. And also, the course of injections, it can take seventy visits to the doctor over five years. But now scientists have come up with an alternative.

And this is work by Gabriela Senti and her colleagues at University Hospital of Zurich, and they found that if you inject the allergens directly into the lymph nodes in the groin - the sort of lymph nodes are the junctions in all your lymphatic vessels, they’re where immune cells hang out and they’re where foreign bodies that come into your body end up being processed by the immune system and recognised. And to test this, they ran a clinical trial of about a hundred and ten hay fever sufferers, split them into two groups.

The first group got the standard treatment, which was fifty injections under their skin over three years, and the second group got just three injections straight into the lymph nodes in the groin over just eight weeks. And after just four months, the group who’d been injected into their lymph nodes were about ten times less sensitive to pollen. You know, the group that was having the conventional treatment took around a year to show any kind of response. And also it's much safer because you’re really decreasing the risk of a massive anaphylactic shock or a very bad reaction to it.

Chris Smith: Why did the researchers see the difference that they obtained when they were injecting straight into the lymph modes?

Kat Arney: Well they think that you’re injecting the thing that you’re allergic to, the allergens, directly to where the immune cells all are, where the immune system is really recognising things and learning. So you’re kind of going straight for the immune system hub really.

Chris Smith: And is it more uncomfortable to be injected in your lymph nodes or is it worse being injected in the skin?

Kat Arney: Well certainly from their study, it seems that the lymph node injections are perfectly acceptable, and if you only have to have a few injections, that’s a lot better than having fifty injections into your skin isn't it?

Chris Smith: Well let’s hope so because I might put myself forward for that. Now this is very interesting in terms of astronomers have made a giant leap for mankind in terms of detecting far off worlds.

Kat Arney: Yes, this is a fantastic story. A little group of planets have been discovered orbiting around a star, and this is the first ever time that direct pictures of planets orbiting around a star, not including our own solar system obviously, have been seen.

Chris Smith: Because in the past of course what we have got used to was people detecting the presence of these so-called extra solar planets indirectly?

Kat Arney: Yes, so, before, you’d see this kind of planets being detected like wiggly lines on a graph of a star’s velocity or brightness. You haven't actually been able to see them directly. And they’re writing in the journal Science this week, and it's absolutely lovely stuff that they’ve done, and it's led by Christian Marois from Canada, and this includes scientists from the US and the UK. And they’ve been using two telescopes that are in Hawaii - which is quite nice, if you’re an astronomer, you can go to Hawaii. But the star that they’re orbiting around is called HR7899. And they first spotted two planets there orbiting around the star back in October last year. And then this summer they found a third planet that was even closer. And this is the first time they’ve directly managed to image a family of planets around a normal star.

Chris Smith: Why have they been able to do this now and in the past we haven't been able to see planets like this?

Kat Arney: I think it's using these new telescopes that they’ve got. The telescopes are really quite sensitive now. And the star is pretty interesting. I mean it's about a hundred and thirty light years away from us on Earth and it's about one and half times the mass of our Sun, and it's about five times as bright, so it's also younger too. So it's kind of like a bigger brasher version of our own solar system. And the planets that they found are about seven and ten times the mass of Jupiter so it's a kind of a big scaled up version of our own solar system. But it is an important discovery because it's now we know that these planets are there, maybe they could play a role in our space exploration in the future if we’re looking for an alternative Earth - who knows?

Chris Smith: Although the planets they did see were quite large, so wouldn’t you have to be quite resilient against the affects of gravity if you were to go and live there?

Kat Arney: You certainly would. I think we’re talking many, many, many years in the future if we ever make it there.

Chris Smith: Now, talking about being big weighty and resilient, let’s finish up finding out how fish elect their leader. We know how Americans do it, tell us about sticklebacks?

Kat Arney: Yes, I'm still feeling the afterglow from the most anticipated election on Earth here, but it is time to turn our attention to the elections of sticklebacks. And researchers in Sydney University in Australia have found out that when sticklebacks choose their leader, they are very shallow and they go for looks.

Chris Smith: We would never do a think like that would we?

Kat Arney: Oh no, never, never at all! And writing in the journal Current Biology, this is work by Ashley Ward and his team, and they found that the fish prefer to follow larger leaders than smaller ones, fat leaders rather than thin leaders, healthy leaders rather than ill-looking leaders, and so on. And they found that these preferences grew much more noticeable as the group of fish got bigger suggesting that there’s some kind of social feedback at work in consensus formation. And David Sumpter, who also is from the Uppsala University in Sweden, and he also worked on the project, and he explained that some fish spot the best choice early on, although others do make a mistake and they go with the wrong fish, and the remaining fish assess how many fish have gone after each leader - and effectively they do reach a consensus about who is the leader of the sticklebacks.

Chris Smith: Now how did they actually do this study because sticklebacks are pretty small? Did they go and look at rivers or did they do this in the lab?

Kat Arney: To make their discovery, the researchers used sticklebacks in a tank in different sized groups, and they showed them two fake sticklebacks that differed in two characteristics - so, for example, a big one and a little one, a fat one and a thin one, ones with different patterns on. This is quite important because if you’ve got a nice fat healthy looking stickleback, that suggests that they’re good at finding food, whereas if you’ve got a spotty stickleback, they might have something wrong with them, they might be ill, so that’s not so good. But the researchers ran trials in which one, two, four or eight sticklebacks had to choose between the two replica fish. And, as the group size increased, the fish made more accurate decisions about which was the right one.

And now you may think, you know, what’s all this got to do with anything, I'm not that interested in fish, but it does tell us a bit about human behaviour as well. Because as we know, recently, things like runs on banks, stock market behaviour are all basically group behaviours and consensus behaviours, and watching others and copying them is quite a good idea if you want to try and get a good leader and stay alive, but maybe not so sensible if you’re working out where to keep your cash.

Chris Smith: And next week, a study comparing sticklebacks to bank managers - no, I'm joking of course, thank you very much, Kat. That was Kat Arney with a roundup of some of this week’s top science news stories. And, incidentally, if you’d like to follow up on any of those items, the details are all on the Open University’s website and that can be found at open2.net/nakedscientists.

In just a moment we'll be finding out how our ancient ancestors had bigger brains than we gave them credit for, that’s on the way, but first to a new system that can predict outbreaks of cholera from space. Cholera of course causes epidemics every year that affect hundreds of thousands of people, most of them in some of the world’s poorest countries. People pick up the infection from drinking contaminated water, and it causes them to develop intense watery diarrhoea which is even capable of dehydrating them to death. Surprisingly, the bacteria that cause cholera are carried by microscopic sea creatures called copepods. But now researchers have found that by using satellites to gather data from the ocean, they can predict where in the future a cholera epidemic is going to happen, and that means that steps can be taken to prevent it. Rita Colwell.

Rita Colwell: Over the years we've determined that cholera is a bacterium that causes the dread disease but it's part of the natural environment. What we've done now is to correlate all the data and use satellites with sensors to take measurements of the key parameters to be able to predict when and where these cholera epidemics will occur. We’re even coming close to predicting how intense they will be.

Chris Smith: And what actually is the cause of the disease? When we talk about cholera, what is the nature of the pathogen?

Rita Colwell: The pathogen is a water-borne bacterium, and it is transmitted by drinking water that has not been treated. That is not filtered, chlorinated and safely distributed. So you can see that it's a disease of the very, very poor.

Chris Smith: And where does the cholera itself actually come from? How does it get into the water?

Rita Colwell: The bacterium is natural occurring. It's associated with plankton. These are the microscopic animals in sea water, river water, fresh water. They’re part of the natural flora. It's just, as we humans have bacteria that are part of our gut flora or intestinal flora and it helps us to digest food, similarly, these microscopic creatures have these bacteria in their gut and on their surfaces.

Chris Smith: So, presumably, if you can spot where the plankton organisms that carry the cholera are or where they’re going to increase in numbers, that will tell you where there might be a risk of an outbreak which means you could pre-empt that and go in with some kind of preventative strategy?

Rita Colwell: Precisely so. By measuring chlorophyll, which has a very distinct band that can be picked up by a monitor and put into a satellite, and measuring sea surface temperature, and even measuring sea surface height, those parameters, we've been able to show, are correlated with high production of plankton. So we’re not really looking for chlorophyll per se, that’s an indicator. It tells us that in about four to six and possibly even eight weeks later there'll be a bloom of those microscopic animals that graze or feed on the phytoplankton which you can think of as the forests and grasslands of the oceans. And then when those populations of plankton become very abundant, we know that very soon thereafter there will be a cholera epidemic.

Chris Smith: How sensitive is this and therefore roughly how much warning do you think you can give medical people on the ground, and is that enough?

Rita Colwell: It's very sensitive. What we have found in this recent paper is that it's quite locality specific. In other words, the timing for Dhaka Bangladesh is a bit different from that for Calcutta. We think we can get precise enough to be able to predict even how intense an epidemic will be.

Chris Smith: And one presumes that if you can predict where the epidemic is going to be, you can prevent it from getting into people, and once you prevent it getting into people, that obviously stops it amplifying in the human population?

Rita Colwell: Yes, we actually did the experiments a few years ago where we hypothesised that if we could remove plankton from the water by just simple filtration, we could reduce the incidence of the disease. So we carried out a three year experiment with about forty-five to fifty thousand people, and we educated the women to use a simple cloth filter to filter their water when they collected it and used that for their drinking water. And our hypothesis was proven correct because we were able to reduce cholera by 50 per cent.

Chris Smith: And a cheap way to do it too. Now looking at the present study, what’s involved in getting the sort of satellite data? Is there enough satellite coverage in order for you to be able to focus on pretty much every cholera hotspot around the Earth and therefore get the kind of predictive data we need in order to break the cholera cycle, or do we need more satellites up in space to take more measurements?

Rita Colwell: We definitely need more satellites and/or better measurements. If we could measure salinity, and I understand that there will be a satellite to do that being launched in 2009, then we will have yet another very important factor that we can measure, that will give even greater precision to our predictions. But you touch on a very sensitive point. There is - or at least there was until the new Election - the possibility that some of our satellites would not be continued, and that I think would be a very serious situation.

Chris Smith: So is the future of those satellites now secured? You say that the Election may have had a bearing on that?

Rita Colwell: Well, I think an understanding of Earth processes as measured by satellite is very important, and I do think that the new Administration will be very favourably disposed to that kind of application for satellite studies.

Chris Smith: And let’s hope they launch that satellite soon - Rita Colwell from the University of Maryland discussing the work that she’s published in this week’s edition of the proceedings of the National Academy of Sciences USA.

Now from the shape of an epidemic to the shape of an extinct species of human and what it can tell us about our own evolution. Well preserved specimens of our ape family of ancestors are extremely rare, which makes it a challenge for scientists to reconstruct how they moved, what they looked like and even how big their brains were. But this is important because details like this can tell us how we evolved to arrive in our present from. Now, Scott Simpson and his colleagues have found a remarkable specimen in Ethiopia. It's of a Homo erectus which is one of our immediate ancestors. These early hominids actually turned into us.

Scott Simpson: The idea is we’re always trying to figure out how modern humans got to be the way they are, and although we can look at human variation in living populations by biomolecular methods or by looking at the anatomy of people, really the only way that we can look at human evolution is through a historical lens. What we’re looking for here in the Homo erectus specimen that we've recovered that’s dated to about 1.2 million years is try to look at body shape and adaptations in birth in this crucial time period of Homo erectus. One of the important things about Homo erectus is that it was during a time period when the brain size of our ancestors was increasing, and what we find is that, what are the changes that are occurring throughout the body in Homo erectus associated with this increase in brain size.

Chris Smith: Because, of course, if the head becomes bigger because the brain becomes bigger, that’s going to have complications in terms of a female having to give birth to a bigger baby?

Scott Simpson: That’s absolutely correct because you can have, two large brain parents can produce a large brained offspring. But if that baby can’t get out of the birth canal, then the mother and the baby are under negative selection.

Chris Smith: So tell us about the specimen that you have found that you think is going to shed a lot of light on this problem, and what it's telling you?

Scott Simpson: Well, what we found is the important thing about this specimen is that it's very complete, and it allowed an anatomically reliable reconstruction of all the major obstetric dimensions and also of the dimensions of the joint surfaces, the sacroiliac joint between the hip joint or the hip bone and the sacrum, and so that allows us to reconstruct or have a look at the anatomy of this pelvis with great anatomical reliability.

Chris Smith: So basically you’re piecing back together what a person, who would have been hung around this pelvis, would have looked like because it's giving you clues as to the stature of that person?

Scott Simpson: Oh that’s right. And the other important thing about this is, although we can reconstruct stature, that this is the pelvis of a female. Now as we were talking about the relationship between increase in brain size and the pelvic adaptations, well the only thing you can look at is a female pelvis. And so here we have is a first complete female pelvis, so we can really see how the pelvis and the brain is changing. As you pointed out, we can also look at things like stature because we can use regressions or estimate the leg length from the size of the hip joint, and we were able to reconstruct the stature of this individual to about four and half feet tall.

Chris Smith: So if you look at what was going on in Africa at roughly the time when this specimen would have been living, does it give you any clues as to or does it fit with what we understand was happening to the weather, what we understand was happening to early humans anyway, or what we think was happening?

Scott Simpson: Well, one of the things that, if we just look at humans that are distributed across the World, and we see people who live in arid tropical environments, they tend to be tall and thin, and when we move to arctic environments, we see that the people are short and stout - or shorter or stouter anyway. We expected to see the same type of variation in body form across the range of habitats in Homo erectus.

So the expectation was that Homo erectus would be a very narrow hipped individual, a very tall individual like we see in modern Kenya and Tanzania and Ethiopia. But in fact what we’re finding is that our individual sort of turns that on its head because we've got a very short individual, much shorter than previously known for Homo erectus and with a very, very wide pelvis, much wider than we see in any living modern population.

Chris Smith: So the hips don’t lie, and you need big hips if you’re going to have babies with big brains. That was Scott Simpson who is from the Case Western Reserve University School of Medicine, and you can find that work published in this week’s edition of the journal Science.

You’re listening to the Naked Scientists: Up All Night with me Chris Smith and time now for this week’s Stuff and Non-Science where we massacre myths and bash bad science and hopefully nowhere near a firing range, here’s Diana O’Carroll.

Diana O’Carroll: This week’s Stuff and Non-Science is the myth told by movies on gun silencers. Are they really as easy to use and effective as we’re told? Here’s Hugh Hunt to explain.

Hugh Hunt: Well you’re never going to get a gun to be completely quiet. Probably a better name for a silencer would be a muffler because it reduces the noise rather than to eliminate the noise. But the first thing we need to do is think about what the sources of the noise are. In a gun, there are three main sources. The first thing is that the gas, the hot high pressured gas that propels the bullet along the barrel, has to be released at some stage. And when the bullet leaves the end of the barrel, the pressurised gas suddenly expands, and that’s what makes the noise. And it's just it like with a balloon.

If I take a balloon, I’ve got a balloon here, and if I pop it, it sounds like this [balloons pops]. Okay. It makes a big noise because the gas inside the balloon is suddenly being released. But if I take another balloon and this time just blow it up, and now I'm going to release the pressure gently [balloon deflating]. Now it's a lot lot quieter. That’s because the high pressure air is released at a slower rate. Now that’s essentially what the silencer or the suppressor does. It gives the high pressure gas space to expand slowly as the bullet leaves the end of the barrel.

Now let’s suppose we've got a really good silencer, and we've got two other noise sources. The first is that the bullet leaves the barrel supersonic, and we get a sonic boom just like with a high speed aircraft. If we wanted to get rid of the sonic boom, well we simply have to slow that bullet down to be subsonic, and maybe the silencer can be designed to achieve that. Now then there’s a third noise which actually you’re only beginning to hear once you’ve got rid of all the other noises, and that’s the click of the trigger mechanism. Now you could imagine James Bond, he goes to fire his gun, and the gun’s not loaded, but what you hear is something like this [click]. Well, it's quite a loud noise, but it's not as loud as the bang from the explosive charge or from the supersonic bullet. Once you’ve got rid of the other two noises, then it does become significant.

Now silencers are most commonly used by hunters say in Alaska, they’re out hunting deer. Really they just want to be not making quite as much noise as they might if they didn’t have a silencer, and maybe it means they don’t have to wear hearing protection when they’re using their guns. But your bog standard silencer is still going to leave you with a gun which is pretty noisy.

Diana O’Carroll: That’s Hugh Hunt, Senior Lecturer in Engineering at Cambridge. That’s it for this week’s Stuff and Non-Science, but if you have a bit of science knowledge you don’t believe in then send it to me diana@thenakedscientists.com.

Chris Smith: So some practical tips for Sarah Palin there next time she’s out hunting for moose in Alaska - thank you 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 that you heard in the programme via the OU’s website, that’s at open2.net/nakedscientists or, alternatively, you can follow the links to get there from the BBC Radio Five Live Up All Night website.

The 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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David Robinson explores The surprising link between brain and pelvis.

Background

These are the sources used by the team in making the show:

In the news

'An Oncogenomics-Based In Vivo RNAi Screen Identifies Tumor Suppressors in Liver Cancer'
by Lars Zender et al
in Cell

'Intralymphatic allergen administration renders specific immunotherapy faster and safer: a randomized controlled trial'
by Gabriela Senti, et al
in PNAS

'Consensus decision-making by fish'
by David J.T. Sumpter et al
in Current Biology

'Direct Imaging of Multiple Planets Orbiting the Star HR 8799'
by Christian Marois, et al
in Science

Interviews

'Environmental signatures associated with cholera epidemics', by Guillaume Constantin de Magny, et al. in PNAS

'A Female Homo erectus Pelvis from Gona, Ethiopia' by Scott W. Simpson, et al in Science

 

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