Question and Answer Show

Inspired by findings from Chernobyl, biologists have discovered that some fungi can grow using radiation instead of light, this may make them ideal for growing in space for astronaut food.

The work began after a robot explorer was sent into the still highly radioactive Chernobyl site and emerged with samples of black fungi found growing on the walls.  It was realised that the black colour of the fungi was caused by the chemical melanin, the same chemical that pigments your skin and makes people go brown in the sun.

Dr. Arturo Casadevall wondered if the radiation was actually feeding the fungi so set up a number of experiments to test his theory.  He found that just like chlorophyll captured ordinary light to convert to energy in plants the melanin could capture high energy radiation to feed the fungi.  It was also found that species of fungi grown in his lab grew much faster when exposed to increased radiation.

Dr. Casadevall is also testing edible fungi which may provide excellent food to be grown in the harsh radiation conditions in space.  The results may also have implications for the possibilities of life on other worlds such as Mars where conditions are much worse than the Earth.

An image processing engineer at Lockheed Martin has just announced that he believes one of NASA's Martian rovers has discovered puddles of water on the surface of the red planet.

Scientists currently believe that Mars is a cold, frigid dessert with very little atmosphere. We do know that there is water ice below the surface in a sort of permafrost, but because the air pressure is so low any water at the surface would just evaporate away.

Ron Levin has been examining photos taken by the Rover Opportunity and has found some intriguing looking images taken about two years ago. What he's found is a series of very smooth, bluish features sat in the bottom of depressions at the bottom of a crater that the rover was exploring. This is perhaps just what you'd expect if they were puddles of water. Levin even claims that you can see small stones below the surface and poking through the water.

Not all scientists are convinced, however. We can recreate the surface conditions at Mars is specially controlled chambers in laboratories on Earth and it seems that it would need some very special weather on Mars to allow water to exist, such as absolutely no winds and summertime temperatures. Another explanation could be that this is actually ice that has frozen in smooth pools on the surface.

Unfortunately it seems we'll probably never find out. The NASA rovers were only supposed to survive 3 months on Mars, but have so far lasted 3 years. Because the images were taken 2 years ago the rover has moved on it's unlikely that it will be possible to send the rover back to have another better look.

If we can get liquid water on Mars then it's a boost for those who believe life might exist on the planet and perhaps the next European Mars mission called Mars express scheduled to launch in 2013 might provide some more answers.

There's nothing worse than hearing a recording of your voice for the first time! The reason is that how we think we sound isn't really how we sound.Inside your ears there is an organ called a cochlea, a special neurological structure that converts the vibrations of sounds in the air into electrical signals that the brain can understand. It gets stimulated by the pressure waves caused by sounds in the air, but at the same time can pick up the vibration of the bones in your skull. When you are listening to sounds in the environment, the chief source of those sounds is coming through the air, very little comes through the bone. When you're speaking, however, your whole head resonates; it vibrates. This means that your cochlea gets stimulated by your skull vibrating, as well as the sound coming out of your mouth and going through the air to your ears.The body does two things; it gets a different version of those vibrations (through the bone and the ear), but it also has a protective mechanism to cut down the amount of sound which is going into the cochlea. It reduces sensitivity of your ear a little when you're speaking, so you get a slightly different rendition of what your voice sounds like.That's why, when you hear yourself recorded and played back, you sound totally different, because all you hear back from the tape recorder is sound coming through the air, minus the skull vibration and bone conduction.

Well, actually yes. Stars are at relatively low density in a galaxy, and so if two galaxies collide, the probability is that actually not one single star would collide in the process.There is, however, a lot of gas between the stars in a galaxy, and this gas would collide and be compressed, and that would, in itself, form a whole new generation of stars. The gravity from these stars would affect everything around them, and you would end up with a great big mess. Here on Earth, in the outer spiral arm of the Milky Way, we would probably survive.David Block, of the University of the Witwatersrand, South Africa, observed the Andromeda galaxy and a nearby dwarf galaxy and noticed a ripple effect in Andromeda. He worked out that if you wind back the clock on these ripples, it puts the origin at about 200 million years ago. The ripples are thought to be the result of Andromeda having previously collided with one of it's companion galaxies, so galaxies can definitely survive such a collision, but it's anybody's guess what the results of this ripple effect would be.Galaxies are not necessarily all moving in the same direction, some, found in clusters of galaxies, orbit each other. In all, it's a bit of a mess! This means that galaxy collisions do happen.We do know that the Andromeda galaxy is going to collide with our own. In about 3 billion years, even before our sun has died, Andromeda will collide with the Milky Way. Maybe future generations of humans, or whatever is living on Earth in 3 billion years, will be able to observe what does happen when two galaxies collide!

Chris -   You've been doing some interesting work on cider, tell us about that...

Serena -   Last year, I was analysing cider apples and looking for different levels of antioxidants, and this year we've released some data about ciders showing that some of them also have high levels of antioxidants.

Chris -   So just tell us what an antioxidant is, what they do and why we need them.

Serena -   Antioxidants are thought to quench free radicals in the body, so these are the really reactive compounds that can do damage within the body, it's believed that these (antioxidants) might help against certain diseases, for example cancer and heart disease.

Chris -   So the more you can pack into your body, the better?

Serena -   That's the theory, yes.

Chris -   So what's the bottom line with respect to making cider, and should we therefore be drinking cider instead of eating apples?

Serena -   The previous work showed that cider apples contain more antioxidants than normal dessert apples, and we've gone on to look at the ciders and found that ciders made from cider apples that contain lots of antioxidants actually have higher levels than those made from other apples.

Chris -   Why is that?

Serena -   I think it's just that the more antioxidants you have in the first place, then more are likely to make it through the cider making process and into the final product.  We found that some apple juices contain lower levels of antioxidants than some of the ciders, and that's again because apple juices are made from dessert apples, which contain lower levels of these compounds.

Chris -   We had Roger Corder from Barts & the London medical school in London on the show earlier this year.  He's been looking at antioxidants in red wine, and the interesting thing he said was that you can't just drink the juice, you need the alcohol. The health-giving compounds, the antioxidants and procyanadin, dissolve in the alcohol, so if you don't have the alcohol you don't get as much of the goodies as you would get from just grapes and pips.

Serena -   Last year I did a feeding study looking at putting people on a low phenolic diet for 36 hours, then getting them to drink a pint of cider and then taking blood and urine.  Hopefully from our data we will be able to understand if you drink a pint of cider how many of these phenolics are absorbed, and we can compare this with data where they used apple juice to see if there's a difference.  Procyanadins are actually found in cider and cider apples as well; in fact cider apples contain very high levels of these, so cider might be a good source of procyanadins.

Chris -   Is a pint of cider a day consistent with good health in other respects?  That could be quite a lot of alcohol, especially if you drink good scrumpy.

Serena -   If you're talking about a 4% cider that's about 2 units [of alcohol], maybe only half a pint of cider might be enough.  We're still trying to work out how much of these phenolics are absorbed while you drink.  Our test subjects were drinking 500 ml to get an idea of how much you would have to drink to get these phenolics into your body.

Chris -   I have to ask Serena, just to finish, who actually sponsored the study?

Serena -   Okay, the study is actually sponsored by the National Association of Cider Makers.

Chris -   Do you think that might have had an impact on the results?

Serena -   No, it didn't! [Laughs]

Chris -   So the bottom line is that you're waiting to see if apple juice is as good as cider, but you get lots of antioxidants from cider, so if you had a choice between beer and cider, it should be cider.

Serena -   Oh definitely cider.  Cider contains much more antioxidants than beer.

The reason a rainbow effect is created on oil is because of interference. Oil on a puddle will tend to create a thin film, which can be anything from 10 to 100 molecules thick, so it's very thin. Each of them can act like a tiny mirror, so when light hits the surface of an oily puddle, some will reflect off the water under the oil, and some will reflect off the oil layers.As light is a wave, if you cause the waves to stop lining up with each other, you can get the 'up' part of one wave aligning with the 'down' part of another wave, and these can cancel out. This is called interference, and it causes a pattern of colours according to how much interference is occurring. Oil films of different thicknesses cause different amounts of interference, so you get a rainbow effect.The same effect is seen on the surface of a bubble, which is also a thin oily film with varying thicknesses.

Chris -   Now Mark Peplow the editor of Chemistry World magazine from the Royal Society of Chemistry is here. What have you got for us Mark?

Mark:  The first story up is a bit gruesome but absolutely fascinating. It's about the former head of China's State Food and Drug Agency, just a few weeks ago he was sentenced to death after being found guilty of bribery and corruption.  This is such a big deal because estimate of the number of people who die in China every year just by taking counterfeit or sub-standard drugs runs in the hundreds of thousands.  This guy Zheng Xiaoyu was in charge of the state drug agency for about 8 years and he's been found guilty of taking bribes of up to a million dollars from 8 different pharmaceutical companies and illegally approving their products.

Chris:  It's quite interesting, because most people don't view China as being the most open country in the world when it comes to giving information and human rights, so it seems strange that they are taking such a though stance on this guy.  Is it because it directly affects people in China that they've done this?

Mark:  It's much broader than that actually, one of the interesting things about the way China's business, industry and science is going at the moment is that there is this huge push to get into the global market place and also to attract investment from abroad into China.  This move to execute Zheng is generally seen as a way to send out a real 'getting though' message to the rest of the world, that the Chinese government are trying to clean-up the amount of bribery and corruption which really spreads throughout the whole state system but has particularly effected the pharmaceutical industry.  It's very telling that on the day that his execution was announced there was no official comment from the Chinese drug agency but they did post the second draft of their revised regulations on how they were going to clean-up their industry.

Chris:  Still a pretty radical thing to just execute someone, I mean we've got people in prison here for doing probably more corruptive things than that, I would think?

Mark:  Absolutely and as many commentators have pointed out, this may actually be a counter-productive move.  Clearly Zheng isn't the only person guilty of corruption within the drug agency.  In fact, there is a great deal of evidence that it's really the negligence of local officials which is the problem here.  I think this is likely to send out a mixed message to pharmaceutical companies who want to invest in China.  It shows that the rule of law is somewhat patchy, it also shows that it's extremely open to political motivation as well; there's been a massive smear campaign against this guy, before he was found guilty, running in Chinese state media for the last 6 months.

Chris:  Well that's certainly food for thought, and talking of food, Atkins; it made the guy who wrote the book an absolute fortune, unfortunately he is no longer here to enjoy that fortune, but people have now found some scientific credence for his argument that eating a high fat diet makes you lose weight.

Mark:  That's right.  The Atkins diet is basically very high in fat and very low in carbohydrates.  It's called a ketogenic diet because it makes your body breakdown fatty acids into a variety of compounds broadly classed as ketones, so breaking down these fatty acids, in theory, should help you slim down.  Now there are two studies that were published last week in the Journal of Cell Metabolism.  The first found that this sort of ketogenic diet stimulates the production of a hormone called fibroblast growth factor 21.  The second study found that this growth factor actually stimulates fat metabolism in the liver.  In this study that was done in Texas, they injected mice with this growth factor and found that it turned on a starvation response, so the mice switch from using carbohydrates to burning up their fat stores as an energy supply.

Chris:  So is this the diet pill of the future then?  Is this the remedy that people have been searching for?

Mark:  Well, there is no way of telling, because this may be the hormone that's responsible for turning your body to burning its fat supplies.  But at this stage the experiments have been done in mice so there is no telling what else it's doing to your body.

Chris:  Hmm... that's worrying.  But talking of putting things in your body that might actually do good things, to end on a high note, we've all heard of cider, now you've got some good news about red wine?

Mark:  Yes, this is a nice, fun story for any wine lover really, a team of scientists at the university of Pavia in Italy have been investigating what happens to wine when you slosh it around your mouth.  It tastes good for a start, but they've found that both red and white wine can actually kill the bacteria that causes caries, otherwise known as tooth decay.

Chris: But isn't that just the alcohol?

Mark: Well, that's the interesting thing, you might think that, but they actually checked this by de-alcoholising their wines prior to the test in order to exclude the effect of alcohol on bacterial growth.  They also checked to make sure that it wasn't the acidity of the wine by making some synthetic wine with the same pH (acidity) and it was nothing like the effect of the real wine.  But they think that they have pinned down the effect to a group of acids called succinic acid, malic acid, tartaric acid that are present in wines, particularly prevalent in red wines. They think that these acids can inhibit the activity of enzymes, which are big molocules that spped up chemical reactions in cells.  Effectively that kills off bacteria, more than 99.9% of all the bacteria in your mouth in one particular case.

Chris: How much better or worse is this than just toothpaste?

Mark: Clearly this isn't the only way that you can kill bacteria in your mouth and there are a variety of mouth washes out there, but if you are looking for another excuse to have just that extra glass of wine, make sure you slosh it around your mouth good and proper!

Chris: The only slight problem is that these red wines have a lot of tannin so you end up with nice, carie-free teeth but it doesn't stop them from going black, at least in the short term?

Mark: That's possibly true but as in all things, moderation is the key I think.

Chris: Thanks Mark. That's Mark Peplow the editor of Chemistry World magazine from the Royal Society of Chemistry, and you can find out more about Mark and what he writes about in his work at chemistryworld.org.

The answer is both!

The background temperature is colder in space than on Earth because we have an atmosphere, which keeps us warm. So at the distance the Earth is from the Sun, it's about -50 degrees Celsius in space.

On Earth, we lose heat through radiation, evaporation of sweat, and by conduction of heat to the air. It is harder to lose heat in space as you can only lose heat through radiation. This is where electrons in the molecules in our body go from a high energy state to a lower energy state, losing energy when they do so by radiating infra-red (heat) radiation.

Conversely, when you face the Sun, you will absorb the Sun's radiation and be warm. But, at the same time, your back will be in shade and will lose heat rapidly by radiation as there's no atmosphere to keep you warm.

In other words, large temperature gradients are found in space, so things get very hot when they are in the Sun's rays, but very cold when they are in shade, so the answer to the question is space feels both cold and warm!