Ancient Hot Stuff

Are you a fan of hot spicy food? Well it seems that us humans have been enjoying fiery food for a very long time indeed. In fact South Americans may have been spicing up their food with chillies for at least 6 thousand years. That's according to a new study which found miniscule traces of chillies in ancient cookware from Ecuador, a discovery that was something of an accident. For years, archaeologists have been scratching their heads over the identity of ancient grains of starch from South America which were not from any of the known staple food groups known from the region like maize and squash. But a team of scientists lead by Linda Perry from Smithsonian National Museum of Natural History in Washington DC, have discovered that modern cultivated peppers, including chillies, have much larger starch grains that their wild relatives - and so taking another look at these mysterious ancient starch grains the team finally identified them as the fiery chilli pepper. So, we now know what has long been suspected but never proven, that the ancient south Americans were using chillies as a spice long before Christopher Columbus arrived and took chillies back to Europe from where they spread around the rest of the world. And perhaps the strangest thing about the ancient cultivation of chillies is why did people do it in the first place? Taking a bite of wild chilli must have been a blistering experience even for the most macho man, so why did people bother going to the trouble of domesticating them?

18th Feb 2007

AIDS Virus Achillies Heel Discovered

Scientists at the US NIH vaccine research centre may have uncovered HIV's weak spot, offering the promise of a target for a vaccine. Patients with HIV make heaps of antibodies against the virus but they don't seem to neutralise it. Now, in this week's Nature, Peter Kwong has dissected the workings of one rare antibody, B12, which can neutralise the infection. It turns out that the virus alters the shape of the docking station it uses to lock onto cells as it infects, preventing most antibodies from working. Making a stabilised artificial version of this docking protein, in the altered shape, might therefore drive the immune system to produce antibodies capable of blocking the effect.

18th Feb 2007

Deep Sea Flirting

This week we've had another exciting glimpse of what life is like in the unseen deep ocean, from a team of scientists led by Tsunemi Kubodera from the National Science Museum in Tokyo who have taken brand new high definition film of a deep sea squid which seem to be behaving rather strangely a very long way down beneath the waves. The Dana octopus squid grows to over 2 meters long and lives between 300 to 900m down in the ocean. It has large glowing bulbs called photophores on the end of two of its eight legs. The new video footage taken off the Ogasawara Islands, in the western North Pacific, showed the squid using these shining lights when hunting - Maybe the squid was trying to confuse or perhaps stun their prey by blinding them with flashing lights or possibly the squid was using light to measure distance to its prey in the pitch black deep sea environment. The team were also surprised to discover just how swift and agile a predator the dana octopus squid is, because it was previously suspected to be sluggish and slow moving. And an even stranger behaviour was observed when the team switched on two torches attached to the outside of their submersible vessel - it seems that the giant squid may have mistaken them for another squid because it showed great interest in them and even seemed to try and communicate with them, flashing their photophores - so perhaps the huge squid was trying to flirt with its new found squid friend, after all it must be a cold lonely place all that way down beneath the waves. Link to film clips: http://www.pubs.royalsoc.ac.uk/media/proceedings_b/papers/Video_clip_4.mov

18th Feb 2007

Venomous Vipers, Artificial Kidneys and LSD

Chris - Time now to find out about various things, including how toads are having their poison stolen by snakes, how we could be a step closer to making an artificial kidney, and we could possibly be unlocking the secrets of LSD. That's because the editor of Chemistry World, the magazine of the Royal Society of Chemistry, Mark Peplow is with us now. So what's this story about snakes that are robbing toads of their toxins?

Mark - Most animals tend to steer clear of poisonous toads, but scientists have found that there's a species of Japanese snake, the Japanese colubrid snake, that actually seeks out toads because it wants to eat them. This is so it can steal their toxins and use them to kill its prey.

Chris - But why doesn't the snake end up succumbing to the toxin?

Mark - Well that's the interesting thing. Now that the scientists involved have actually found out that it's able to do this, they hope now that they're going to be able to work out why it does this. What they did was analyse two different groups of snake. One of them was fed on these toads and the other one didn't have the toads in its diet. They found that it was only the ones that were able to eat toads that ended up being poisonous.

Chris - So it's not a genetic difference, it's purely a dietary difference.

Mark - That's right. There's a small island off Japan where these snakes don't have access to toads, and they found that if they took snakes from that island and gave them toads, they ultimately became poisonous after a relatively short time. When they looked at exactly what molecules the snake was using, they found that they'd actually changed the molecule slightly. So they'd taken them in in one form from the toads and tweaked them chemically. Now that, the scientists speculate, might be the reason why the snake isn't poisoned by the toads because it can rapidly change their chemistry to stop it doing them damage.

Helen - I also hear that there have been steps towards a new type of membrane that could allow us to create a new type of kidney.

Mark - That's right. Scientists announced this this week. What it is, is a filter for molecules and it's just about 15 nanometres thick - that's 15 billionths of a metre thick. That's at least 1000 times thinner than a piece of human hair. It's like a sieve that you would sieve your pasta with in the kitchen apart from the holes are about a million times smaller. Now this is important for a variety of reasons. In laboratories you need to separate proteins, very big tangled molecules, from smaller biological molecules for analysis. But that's exactly what's going on in a dialysis machine as well. Now given the success scientists have seen with this, they've found that it speeds up the separation of these molecules by at least an order of magnitude. That's at least ten times faster. In the test that they did where they were comparing small fluorescent dye molecule with a big fat protein called bovine serum albumen, they found that what would normally take a couple of hours using a couple of polymer membranes that you see in dialysis machines, they could achieve the same thing in six and a half minutes. Now if you could get this working in a conventional dialysis machine, that potentially speeds up the process immensely. Now they're not there yet, but this is a very promising material and moreover it's really quite tough and relatively easy to manufacture. This mainly because it's made out of silicon, the same stuff that goes in silicon chips in your computer.

Chris - Especially given how much dialysis costs the NHS, because it's a very expensive process to do. But Mark lastly this week, you've got an interesting thing about how unlocking LSD sends us on the trip of a lifetime.

Mark - Yes this is a nice short and sweet little story actually. Brain researchers have always been confused about why LSD has such a different effect in the brain in comparison with other drugs that work in what appears to be quite a similar way. When people take LSD, the molecules hit a receptor in the brain called a serotonin receptor. Normally this is used to recognise this molecular messenger in your brain called serotonin. But if you have a drug like LSD hitting that, why then don't other drugs like sleeping pills, which also hit serotonin receptors, give you hallucinations? The researchers have found that it's basically because it's not a two-stage on-off switch. This receptor can either be 'off', or it can be 'on' by LSD which sends out one chemical cascade of reactions that ultimately gives you hallucinations. Or they compared another drugs that's very similar to LSD in the way that it works in the brain called lysuride, which is an anti-Parkinson's agent. They looked at exactly how that was interacting with the serotonin receptor and they found that it was switching it to a third position, which researchers hadn't known about before. Now ultimately understanding how this serotonin receptor switches is actually quite important for a variety of psychiatric reasons because you can potentially make new drugs that can target these different positions of the serotonin receptor.

Chris - That was Mark Peplow who's the editor of Chemistry World, which is the magazine of the Royal Society of Chemistry. You can find out more about those stories at their website which is www.chemistryworld.org.

February 2007

Maths Exams and drugs

Bob - This week for the Naked Scientists, we're bringing you stories from the annual meeting of our organisation, the American Association for the Advancement of Science, going on right now in San Francisco, California. I'm going to tell you why smart kids choke on mathematics exams, but first, Chelsea has this story about how drugs work in your brain.

Chelsea - If you want to know what it's like to be addicted to cocaine, you might imagine being really, really hungry. That's according to Friday's presentation by neuroscientist Nora Volkow, director of the National Institute on Drug Abuse. She found that the brains of cocaine addicts release the pleasure chemical dopamine when exposed to drug cues, like images of people using drugs or drug paraphernalia. She says that's the same thing that happens in the brains of food-deprived people exposed to food cues, but to a lesser degree.

Nora - What drugs are doing is taking advantage of circuits that are there for a very specific purpose. The circuits that are tapped by drugs are those that will ensure that we will do behaviours that are indispensable such as eating.

Chelsea - And she says that's why addicts can't resist the urge to get high any more than a starving person could resist the urge to eat.

Bob - Thanks, Chelsea. The best mathematics students are also the most susceptible to choking under pressure. This according to the work of University of Chicago psychologist Sian Beilock, who spoke here yesterday. Her team found that top students rely on their superior working memory to solve complex problems. But average students often fall back on less accurate shortcuts, like estimation.

Sian - Under pressure, however, our higher working memory individuals didn't continue with the complex algorithm. They actually switched to the shortcut. So their performance looked like the lower working memory individuals' under pressure, and now we have some idea why this is the case.

Bob - She said that because pressure appears to sabotage working memory, high-stakes exams may not accurately identify the best and the brightest.

Chelsea - Thanks, Bob. Next time we'll be back in Washington, DC, bringing you stories from our side of the Atlantic. Until then, I'm Chelsea Wald.

Bob - And I'm Bob Hirshon, for AAAS, The Science Society. Back to you, Naked Scientists.

February 2007

Why sodium street lights make things look orange

Many people are familiar with the phrase 'as sure as eggs is eggs', but can we be as sure that orange is orange? It turns out that the answer is no, and to reveal why, Anna and Dave go to Cottenham to carry out some Kitchen Science with enthusiastic helpers Luke and Alice.

What you need

What to Do

1 - Look at the magazine in normal light. What colours can you see?

2 - Go outside and look at the colours again under an orange (sodium) street light. How are the colours different?

3 - Look at the colours under a normal orange light like a car indicator

What may Happen

In normal light you can see lots of different colours on the magazine - in fact, it looks just like you'd expect! However underneath the orange street light, the magazine looks various shades of yellow.

What is going on?

Firstly we need to look at why we can see the colours in normal light. White light contains all the colours of the rainbow from red through to blues and purples. Each colour has a different wavelength, but if you add all the wavelengths together you end up with white. If you shine white light onto an object and it looks green, this means that most of the red and blue wavelengths have been absorbed by the object and the green wavelengths have been reflected into your eyes. Similarly if an object looks blue, it means that most of the red and greeny wavelengths have been absorbed, which leaves the blue to be reflected.

So why do all colours except yellowy-orange disappear when we look at the magazine under the street light?

Street lights are a very special kind of yellow light in that they only produce a very narrow set of colours. So rather than giving out a bit of every colour of the rainbow (as with white light), only yellow-orange wavelengths are given off. When this light hits the magazine there are only two options: either the ink on the page absorbs yellow-orange light, or it reflects it. If it absorbs yellow light then there is nothing left for it to reflect - remember that these street lights ONLY produce yellow-orange light and don't give off green and blue and all other colours - and if there are no wavelengths of light to reflect back, then we just see shades of grey. However if the inks do reflect yellow, then we will see yellow colours on the page. The overall outcome is a magazine that appears to be various shades of yellow-orange and grey - essentially monochrome.

But this doesn't happen under all orange lights. What happens if you look at the magazine under the orange indicators of your car?

It turns out that you can see all the colours visible under normal light conditions... spooky! Under the orange street light we could only see yellow and grey, but under the light of an orange car indicator we can suddenly see them all again. Why is that?

Thankfully it's not that spooky at all because there's actually more than one way of making orange light. You can either make it out of pure orange light, as is the case with a sodium street light, or you can make it out of a mixture of red wavelengths, a bit of green, a few yellow wavelengths and a bit of orange. So just as white light is made from lots of different wavelengths, the light from an orange indicator is also made from different wavelengths. This means that when the light hits the magazine, the inks that reflect green are able to reflect green and the inks that reflect blue can reflect blue, and so on. And this is possible because there are a range of different wavelengths given off in the first place.

So although the two types of light both look orange to us, they are in fact very different: one is made of pure orange and the other is orange made from a mixture. The conclusion is therefore that we can't be sure that orange is orange unless we try this experiment, and you'll have to wait for another Kitchen Science to discover if we can be sure as eggs is eggs.

Written by Dave Ansell