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The Naked Scientists: Science Radio & Science Podcasts

19th Jul 2008

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Discovering Drugs

Drug Discovery: On this week's Naked Scientists, drug development goes under the microscope as we explore two new ways to find the treatments of tomorrow. We find out why size is important when it comes to chemicals that can kill superbugs, and how soil bacteria hold the chemical clues to the next generation of antibiotics. Plus, how sheets of carbon can be used to reveal single atoms of hydrogen beneath the microscope, how scientists have homed in on the part of the brain linked to obsessive compulsive disorder, and why electronically tagging jellyfish can tell us a sea turtle's secrets. Plus, in Kitchen Science, we make strange and unexpected shapes with bubbles!

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Smallest atoms seen for the first time

A team of US scientists have achieved a genuine quantum leap in imaging - with the development of a technique that's enabled them to see, for the first time, the smallest atoms, including hydrogen. Graphene - a carbon lattice

Writing in this week's Nature, UC Berkeley researcher Jannik Meyer and his colleagues placed a sheet of graphene, which is a single layer of carbon atoms arranged in a honeycomb configuration beneath an electron microscope. In the electron beam they were able to pick out tiny dots, like stars in a cloudless sky, which were individual atoms of various types that had landed and stuck to the graphene sheet.

Incredibly, alongside the carbon atoms that were relatively easy to spot, were some fainter smaller dots which fitted the bill both electrically and in terms of their appearance to be hydrogen atoms. The team were also able to image whole molecules including hydrocarbon chains, which as one might predict formed lines across the image.

The amazing results are thanks to the choice of graphene as the backdrop for the imaging. Being one atom thick and highly regular in its configuration it's very easy to subtract electronically from the signal to leave just the image of the atoms. Graphene is also very sticky, so it holds onto the atoms and molecules that land on it very tightly, and it is also very robust so it can withstand the intense beam of electrons hitting it.

At the very least this technique promises to open up new vistas in imaging, including the ability to study the shapes and arrangements of atoms in complex molecules.

Reference: Nature 454, 283-284 (17 July 2008) | <abbr title="Digital Object Identifier">doi</abbr>:10.1038/454283a; Published online 16 July 2008

20th Jul 2008

The details in the devil - how a tumour is driving a sexual shift in Tasmania

Researchers in Australia have shown that the Tasmanian Devil, beleaguered in recent years by a transmissible fatal facial cancer, has responded to the disease threat by a dramatic change in its reproductive habits.

Writing in this weeks PNAS, University of Tasmania scientist Menna Jones and her colleagues looked at devil population data from five locations around Tasmania. Prior to the appearance of devil facial tumour disease, the data shows, the animals lived an average of 5-6 years, began breeding from the age of two years and raised several litters of offspring over their lifetimes.

Now the animals, numbers of which have fallen by nearly 90% since the disease first appeared in 1996, are breeding once, at less than a year old, and may not even survive long enough to rear that litter.

The reason for this precocious sexual maturity isn't known, but scientists suspect that a combination of factors including less competition from other devils, reduced population density and more plentiful food may be responsible. What it means to the devils is even more unclear, although it could prove to be their salvation if it leads to the emergence of animals that are resistant to the disease, which is thought to behave like an infectious organ transplant spread when the animals fight and bite one another.

However, there are very few devils left and their genetic diversity across Tasmania is generally very low, which means that will be difficult for natural selection to pick out animals that are resistant to the disease and for these animals to replace the population. Consequently the team are not optimistic, sombrely suggesting that the animals may be extinct in the wild within 25 years.

"This novel disease could have catastrophic consequences for the Tasmanian devil," they said.

Reference: Published online before print July 14, 2008, doi: 10.1073/pnas.0711236105

20th Jul 2008

Obsessive research highlights cause of OCD

Scientists in Cambridge have pinpointed changes in brain activity underlying obsessive compulsive disorder. The discovery could lead to more accurate and earlier diagnosis of the disabling condition, which affects between 1-3% of the population, runs in families, and is associated with frequent intrusive thoughts (obsessions), which provoke sufferers to perform recurrent rituals (compulsions) such as hand washing or turning lights on and off. These symptoms can be very distressing and can take up hours of a patient's time. They're often also diagnosed late, which might also make them harder to treat when the sufferer eventually seeks help. The human brain

But that could be about to change; writing in this week's Science, Sam Chamberlain and his colleagues recruited 14 people suffering from OCD, 12 of their immediate relatives, and a control group of 14 unaffected individuals. In a brain scanner the volunteers were shown two pictures side by side of a house and a face. They were then asked to press one of two buttons to indicate which of the two images was the "correct" answer, which they had to work out initially by trial and error. After the correct "target" had been identified six times in a row it changed, so that the subject had to learn again.

The researchers then compared the patterns of brain activity between the subjects and found that amongst the OCD sufferers and their relatives a brain region called the lateral orbitofrontal cortex was consistently less active. This region is concerned with reacting to change, which explains the ritualistic behaviour shown by OCD sufferers.

"Impaired function in brain areas controlling flexible behaviour predisposes people to developing the compulsive rigid symptoms that are characteristic of OCD," says Chamberlain. "This study shows that these brain changes run in families and represent a candidate vulnerability factor. The current diagnosis of OCD is subjective and improved understanding of the underlying causes of OCD could lead to more accurate diagnosis and improved clinical treatments."

Reference: Science 18 July 2008: Vol. 321. no. 5887, p 421 - 422 DOI:10.1126/science.1154433

20th Jul 2008

Keeping Tabs on Jellyfish

Jon Houghton, Queen's University Belfast

Ben - We now have John Houghton on the line. Thanks very much for joining us. You are studying turtles so why is it that you’re tagging jellyfish?

Jellyfish Jon - Leatherback turtles are the ones that eat jellyfish and they cause a bit of a problem for us because they’re not like a typical migratory species that moves from one spot to another. They just fan out through the entire ocean. We, for a long time, haven’t actually known where they were feeding or what they were feeding on. [For] a couple of years we did big surveys of the whole Irish Sea. What we found was not what we thought we were going to find. We thought the jellyfish were just going to be randomly everywhere. What we found was in four or five main bays. You get these hundreds of thousands of giant jellyfish that are there year after year after year. When we modelled the distribution of leatherback turtles we actually find they’re tied up in the same place. That wouldn’t be very exciting if you work on land but when you work on an animal that lives beneath the sea and you can never blimmin’ find it actually just a simple thing of tying predator and prey is very good.

Ben - How do these electronic tags work? I’m guessing these are not the things that report you’re not in your home when you should be?

Jon - No but they’re not a million miles away from it. They’re data storage tags and they’re tiny – they’re about the size of your little finger. The ones we’re gonna do this year are quite simple. They’re just going to record depth and temperature and light levels. We just put it on to a jellyfish. It records all the information and then eventually we retrieve the tag.

Ben - I’ve seen plenty of jellyfish washed up on the beach. They’re very squidgy sort of fluidy things. How on earth do you attach an electronic tag onto something that’s so amorphous and blobby?

Jon - That’s true but there’s jellyfish and there’s jellyfish. I think the ones you’re describing would be called aurelias. They’re common jellyfish. They’re tiny and floppy and wobbly and they would be almost impossible to tag. The ones we’re going after are called barrel jellyfish and they’re massive. They’re nearly a metre across and weigh 27-28kg. They are actually quite big, tough animals. They’re very strong swimmers, they can swim against a current. Actually if you think your jellyfish are looking like a mushroom. You’ve got the stalk part coming out underneath what we call the bell. Quite simply all you do is you just tie a time and depth recorder to a plastic cable tie, swim up to the jellyfish: tie it around. It takes about ten seconds.

Ben - Does this affect their behaviour? They must not like having something stuck round their body.

Leatherback Sea Turtle Jon - They’re very simple animals and they do react. That’s true. We did trials off the West of Ireland last year. Not surprisingly, when you attach a tape to a jellyfish it just swims to the seabed and tries to get away from you. What we found, after an hour or so, they’ll just move back up in the water and get on with jellyfish business. As long as you ignore those first few hours then it’s fine. You’re talking about a device that is 0.1% of the whole animal’s body weight. It doesn’t really affect it that much.

Ben - How long are they going to keep these tags on? When are you expecting to get this data back?

Jon - That we don’t know the answer to. The particular jellyfish we’re going after – they’re unusual. Most jellyfish boom and bust for a couple of months in the summer. These guys seem to be around all year. We’re going to put the tags on probably in August and I’m sure they could be turning up anytime between say two months to maybe even a year down the line. So yeah, any time over the next year.

Ben - How do you actually collect this data? Does it just float up from where the jellyfish were?

Jon - What we’ve got attached to the time-depth recorder, a little dive computer, is just a tiny fishing float. On the fishing float is just a little label with a reward on it. Once the jellyfish dies the whole device just detaches itself from the jelly and floats to the surface. We’re putting them on in big bays where we know they will wash ashore. If you find one on the beach just pick up the reward label and give us a call.

July 2008

Going loopy for bubbles

We discover a surprising feature of bubbles using only bubble mix, wool and a coat hanger!

What you need

	A coat hanger or other source of wire		Wool or string
	Some washing up liquid		A tray

What to Do

The bubble loop First bend the wire into something that is roughly a circle.

Wrap the wool or string around the wire to form a loop of wool covered wire. This will act as a reservoir for the bubble mixture making the film last a lot longer.

Tie two fairly loose pieces of wool across the middle of the wire loop forming 3 sections.

Mix a generous amount of washing up liquid (3-4 times as much as you would use for a whole bowl) with water in your tray.

Place the wire loop in the mixture and gently remove it leaving it covered with a bubble film.

Pop the central area of film, what happens.

Try popping the others, and starting again and popping them in another order.

What may Happen

You should find that the wool is pulled away from the area of film you popped.

What is going on?

Water and all liquids have a property called surface tension, this acts as a force trying to make the surface of the liquid smaller. The washing up liquid you added to the water will have reduced this surface tension enough to form a bubble film, but it is still there. This means that when you first form a bubble film on the loop, the film is in tension pulling on all of its edges. The loose strands of wool are pulled from both sides, so the forces cancel out and the wool stays loose.


The film's surface tension pulls on both sides of the wool so it doesn't move.	When the central film is popped there is only a force on one side of the film so the strands are pulled apart.

Forces in a bubble skin When you pop the central film, you're left with a film on only one side of the wool, so it can be pulled sideways by the surface tension, allowing the film to shrink.

This surface tension is the reason that bubbles are spherical (ball shaped) this is the shape with the smallest area for a given volume of air inside, so if there are no edges surface tension will always pull a bubble into a sphere.

What is Surface Tension?

Surface tension is caused because the molecules in a liquid are attracted to one another (otherwise they would wander off and it would no longer be a liquid). In the centre of the liquid these attractions will act in all directions, and apart from stopping the liquid falling apart they have very little effect.

However at the surface of a liquid there are no liquid molecules above, so a molecule on the surface will feel an overall attraction back into the liquid. This means that unless something is holding the surface up, it will tend to shrink, this tendency we call surface tension.


In the middle of a liquid a molecule is pulled in all directions so there is no overall force.	On the surface there is an overall force back into the liquid, this means that unless the surface is held up it will shrink.

Written by Dave Ansell

	How does coconut milk get inside the coconut in the first place? Jeremiah
	There’s an issue here because coconut milk is actually slightly different to coconut water. It’s coconut water that you find inside a coconut. That’s not water that’s got in from the outside, it’s created by the coconut itself. It’s actually what we call the endosperm of the coconut plant. That’s the stuff that gives the nutrition for the developing seed, a bit like the flesh of a banana. As the fruit ripens the coconut water gets converted into the solid fruit that you find in there. If you have an unripe coconut the water will be quite sweet and very nice. The riper it gets the less pleasant it gets to drink.
	July 2008
Comment on this... Jeremiah asked the Naked Scientists: Can you please explain how coconut water gert into the fruit and what is its function and uses? What do you think? - Jerryade - 19th Jul 08 When coconuts mature, what will be the white flesh starts as a thin layer of clear jelly. The jelly gets thicker and more dense as the coconut gets older until the dense meat that we are after is all present, lining the shell. While this is happening, the juice (milk) which is mostly water (from the ground via the tree's phloem cells) starts off a bit cloudy but clears and becomes sweeter (through photosynthesis)as the coconut matures. The protective inner shell develops simultaneously as does the fibrous outer shell that we don't tend to see very often but is useful as a floor covering when woven. - blakestyger - 19th Jul 08 See the whole discussion \| Make a comment

	Are there any mental or psychiatric conditions that are known to be hereditary other than OCD? Rolly Mandelbrot, Second Life
	Yes. Schizophrenia – we know that the risk rises very much so if you have a first degree or near-relative with the condition. Also bipolar disorder. They’re two very common conditions. They affect between one and two percent of the population. Scientists are now beginning to apply the power of molecular biology to try to find out what the genes are that are linked to these conditions. They’re using something called single nucleotide polymorphism analysis or SNP analysis. What this involves is a big group of people who have the disorder, a group of people who don’t have the disorder and then you look across their DNA for these little molecular markers called SNPs to see if they crop up more often in certain places of the genome in people who have a condition than people who don’t. That gives you a kind of flag sign or a way-marker to say this bit of the DNA might be important in this condition. Then you can focus your attention much more closely in that area. The same analysis has proved that there are various other genes that, in addition to the ones we knew about, are linked to things like genetics for breast cancer and diabetes in the last twelve months. I think we’ll probably see quite a lot of fruit being borne out by that procedure quite soon.
	July 2008

	I have a brand new iPod. It’s never been charged and has no data put on it. Will it weigh more after charging the battery and filling it with music and pictures? Neil Pariser
	It will, Neil, if you fill it with heavy metal (!) But really, the answer’s no. The way in which an iPod works depends on which one you’ve got. If you’ve got the one which is solid state memory then all it’s doing is binary data. It’s just a memory chip which is storing information as digital information. If you’ve got the older, bigger iPods that have hard-discs in them this is magnetic binary data. In each case it’s either storing a 1 or a 0 by having something pointing in one direction – a piece of magnetism pointing one way or the other, effectively. You can think about it like that. That doesn’t actually matter whether it’s actually got anything stored on it or not because storing nothing still weighs the same as storing something. It’s not like a cupboard that you’re putting tins into. On our forum, Madidus Scientia, put this very well when they said it’s a bit like having a handful of coins and they’re either heads or tails. That’s like the 0 or 1 in digital binary. They weigh the same whether they’re all showing heads or they’re all showing tails. There’s no reason to think there should be a difference in the actual weight. However, When you charge the battery you are adding energy and there is a relationship between energy and mass... As Einstein said E=MC² so when you boil your kettle or, this is the best excuse for not doing P.E. at school, when you run in both cases the hot kettle or you running have more energy. When you’re running faster you have more kinetic energy. Because E=MC² – that’s E, energy, equals M, mass, times the speed of light, C, squared. Since the speed of light, C, doesn’t change if your E, energy, goes up your mass must go up. So a hot kettle will weigh more and when you run in P.E. you will gain something like 10^-14g. This is not a prodigious weight-gain but it is nonetheless weight gain due to taking exercise. You could use this as an excuse for not doing exercise. Similarly, in your iPod when you charge it up you’re putting energy into the battery. It will weigh a rather tiny amount more. One statistic I did hear is that a thumb print applied to the front of the iPod in the form of, say, the grease on your thumb will weigh thousands of times more than the weight of the battery will increasing due to charging it!
	July 2008
Comment on this... Neil Pariser asked the Naked Scientists: If I get a brand new iPod at the store which has neither a charged battery or any data on it, does the iPod weigh the same after charging the battery and filling it with music and assorted pictures? What do you think? - Neil Pariser - 15th Jul 08 It would weigh more by the most insignificant tiny unmeasurable amount after it has been charged, but no, the data has no weight. Think of holding a few coins in your hands, 2 showing heads, 1 showing tails. If you flip them all so that they all show tails they still weigh the same, but show different information. - Madidus_Scientia - 15th Jul 08 From simple physics I can't see that a battery will add weight when charged. If it were true then discharging would reduce its weight. Electrons flow from one plate through the external circuit (although individual electrons don't make the whole trip) and back to the other plate.. The exact same number will return to the battery. The diluted acid in a lead-acid battery will increase its weight when charged..a hydrometer measures this to check on the state of the battery...but the lead plates will lose weight and there will be no overall change. More esoteric physics(such as quantum mechanics) may suggest otherwise. Writing data to 'new' (maybe unformatted) flash memory involves injecting tiny currents so there may be a very very small but finite increase in weight. Deleting may just prepare the memory for over- writing and not remove the charge on the gates of the Mosfets. - Pumblechook - 15th Jul 08 M-S's argument involves the E = mc2 argument and must be right. A similar argument around the memory elements could take you either way - does a 1 correspond to more or less energy than a 0? That has to depend on what logic technology is used. The total system would have to be electrically neutral before and after your 'injection' of currents so there would be no mass added or taken away. I think, basically the answer to the original question is "No". - lyner - 15th Jul 08 As a firm believer in empirical study I drove to a public weigh station with a non charged and empty ipod.......weight of car plus non charged and empty ipod 1431kg..........I then charged up the ipod and filled it with songs and did the same....the result ? 1431kg....voila !! Glad I could help ! - neilep - 15th Jul 08 I agree with Sophie & M-S. Using E=mc2, if the energy of the battery increases then m must increase to keep the equation balanced. - DoctorBeaver - 15th Jul 08 Neil I dont believe YOU Can i ask ,did you check to see if your car battery was in the same state of charge on both occasions. No i bet you didnt ? This may obvious but in between your trips did you refill your car with petrol so it had the same amounts whilst sitting on the weigh bridge ? Also was it sunny on your second trip , did you look into whether a car weighed more if its body was warmed by the sun. And i bet you didn't remove all those the flakes of skin and hairs that fell off your body in between trips. - ukmicky - 15th Jul 08 And he'd had a dump! - DoctorBeaver - 15th Jul 08 If the weighbridge was accurate to 1kg, that would correspond to a possible error of 10e17J. The ipod battery would store something like 1MJ. So . . - lyner - 17th Jul 08 The first time I heard this podcast, I thought your answer of E=MC2 might be wrong. Because charging the battery only move electron from one chemical to another. So the total mass should not change. And I thought E=MC2 only works when nuclear reaction taken place. After searching through Wikipedia, I found out that, the formula works even with normal chemical or physics reaction. Physics, for instance, when something speeds up, its would gain more mass. And when you charge the battery, electron moves from a track of an atom to another track of another atom. Then the electron moves faster(probably..), and because it moves faster, it gains weight. That is my explain to this. - ksc91u - 16th Sep 08 There is a difference in weight when downloading music files, especially if you are down loading heavy metal or rock; The equation is quite simple, vis: M + V(ΘΘΨΦδ x ωλ8 ) Σ + #of downloads : XL5 = Bullshit - Don_1 - 17th Sep 08 Sorry but it's not this the reason. Even if there weren't any electron movements at all the battery's mass would increase the same because of the flux of electromagnetic field (which carries energy). - lightarrow - 18th Sep 08 Do you mean that if we let a current flow over a wire, the weight of the wire would also increase? When a current flow over a wire, electrons are moving faster? than when they are on the track, right? - ksc91u - 18th Sep 08 Do you mean that if we let a current flow over a wire, the weight of the wire would also increase? When a current flow over a wire, electrons are moving faster? than when they are on the track, right? What I mean is that an electromagnetic wave can convey energy as well, you don't need to think about masses or charges exclusively. If you heat the battery with a flame or with a hot lamp, you increase its mass; if you send a light beam inside of it, you increase its mass, and so on. - lightarrow - 18th Sep 08 See the whole discussion \| Make a comment

The Search for New Drugs

Dr Harren Jhoti, Astex Therapeutics

Chris - Joining us in the studio this week is Dr Harren Jhoti who is the founder of the drug discovery Astex Therapeutics. He set this up in 1999. He started off as the chief scientific officer and he’s now the chief executive officer. Harren, thank you for joining us. What’s the basic way in which, before you came along with your techniques, we were trying to invent new drugs? Lab bench

Harren - The conventional approach to discover new drugs really starts with initially finding a target which may be associated with a particular disease. That target, quite often, is a protein which malfunctions in one way or another. Sometimes it’s hyperactivated the protein’s function. What you then do is you take that protein and then you screen it against a collection of compounds. Basically these are libraries of chemical entities. Quite often these libraries are really rather huge in the sense there could be hundreds of thousands of different compounds. The aim there is to identify some compounds which actually bind or interact with that target protein. Those are called leads in the drug discovery terminology. After that what happens is you try to optimise those leads by doing some iterative chemistry, i.e. you try to improve the interaction of those compounds against the target protein. You try to impart in those compounds the drug-like properties one needs for that compound then to become a drug.

Chris - In the real world how long would it take between you coming up with a structure for something in the body you want to target. Say you find a gene which makes something linked to, say, high blood pressure and you want to make a drug to lower blood pressure by blocking that gene. How long would it take if you invented a molecule between the invention of that molecule, the conception in the laboratory, and it actually going into a patient? What’s the average time?

Harren - You know, this process and procedure is a really very long time. It takes many years and it ranges between five to ten years often to go from the concept to a drug which may get onto the market place and to treat patients. That’s why it requires a huge amount of investment in this whole process.

Chris - What’s the average price tag for a drug coming out today?

Harren - The kind of monies it requires to develop a drug is in the order of $800 million.

Chris - Wow.

Harren - That number also does include a lot of the programmes which actually fail to generate the compound.

Chris - So that’s why pharmaceutical companies when they make a drug have to charge a lot for it? Certainly to the first world, in order to make their money back to bankroll the development of other drugs that are not going to succeed?

Harren - That’s exactly right. The actual failure rate is really quite eye-watering, in fact. Depending on where you look at the process, what the metrics are. They range in the order of one in 100 or one in 1000 compounds actually get to the market place.

Chris - Why do most not make it?

Harren - That’s a big question and a lot of people are trying to understand how we can improve this productivity. One thing which is quite clear from looking at the types of chemistries which have been generated using this more conventional approach is that perhaps these molecules have become too molecularly complex. Perhaps they’re a little bit too large. What happens then in the body is that some of these compounds are actually metabolised in a negative way which generates toxicities.

Chris - So you’re saying the actual drug that the company might make ends up being far too big and ends up turning into other things in the body which can have harmful effects. That’s why the compound fails?

Harren - There is clear evidence which suggests that the attrition or the failure rate of compounds which are being developed in the clinical setting is correlated with the size of the molecule.

Chris - Do you think it’s also correlated with the size of the legal bills that companies like Merck have been facing? When they come up with a drug and then get sued for a billion dollars a few years later because of consequences which came to light later this is probably a massive disincentive, isn’t it?

Harren - There is no question these are broader societal pressures on the industry. I think in a very general way society has perhaps become a little bit overly risk-averse. There’s no question every drug will be toxic to some degree, depending on the dose. The whole question here, or the challenge, is to give appropriate amounts of drug to deal with the disease and not generate toxicity.

Chris - What’s the approach you’ve been taking at Astex to do it differently and surmount some of these difficulties?

Harren - The key issue that we’ve been trying to target is to try to keep the eventual drug candidate, the drug molecule, slightly smaller – slightly less complex. What we do is, rather than screen these compounds which are quite often between 300-500 Daltons in size we actually screen much smaller chemistry: between 1-200 Daltons. [1 Dalton is approximately the mass of a hydrogen atom] These are what we call fragments. Then what we’re able to do is add chemically to those fragments to improve the interaction of those fragments to the target protein.

$X-Ray diffraction$ Chris - Still sounds like an enormous amount of work, though. How are you able to do this and do it more efficiently and more cost-effectively than other companies? If it was that easy they’d be doing it.

Harren - There’s no question it is difficult. What we’ve been doing is focussing on how you would optimise the technology to be able to firstly detect these very small fragments which is a technical challenge in itself and then to optimise. What it really boils down to is visualisation of how these fragments bind. We’ve developed biophysical techniques: x-ray crystallography, NMR and integrated the suite into an approach which we call Pyramid to allow us to do this fragment-based drug discovery.

Chris - Talk us through the Pyramid bit-by-bit, exactly how you would go about your technique for making a new agent.

Harren - Once we’ve identified the target protein we then produce the three-dimensional structure in that protein by doing x-ray crystallography. For that you have to do a lot of protein expression and biochemistry.

Chris - So that gives you the shape and what the molecule actually looks like. How does that help you?

Harren - That helps in two ways. Firstly, it tells us exactly where a fragment has been bound to that target and that allows us to rationally optimise that fragment to fit better into that target protein.

Chris - So that gives you the business-end of the drug so you know which bit is doing the important job?

Harren - That’s right. Then what we could do really is what we’re doing is hand-crafting these molecules to very uniquely directly fit into the pockets of the protein. The other key advantage of his approach is that these fragments are very low affinity. They bind with very low interactions and it turns out that biophysical techniques such as x-ray crystallography and NMR are really much better ways of detecting the original binding of the fragments.

Chris - Then where do you go?

Harren - What we then do is do several cycles of optimisation. We add extra functional groups onto these fragments and grow these fragments out, very much like a seed. Like planting a seed and growing a seed. Once we actually have molecules which have the appropriate profile in terms of the properties one requires from a drug transit these molecules are then tested in human beings. Of course before you do that you have to test them in preclinical models.

Chris - Once you’re arrived at this molecule you want to make how do you actually get it so you can make it efficiently? If you end up with very complicated chemistry and needing to make these very complicated but small molecules, how do you make them?

Harren - It turns out actually the fragments are very simple, much more simple, than the larger complex molecules which conventional screening or conventional drug discovery actually use. The chemistry’s simpler and less chemically challenging than conventional drug study.

Chris - Have you got drugs that are actually out there in the clinic or which are just experimental at this stage?

Harren - We’ve put three compounds now into clinical trials. Our particular focus today is developing the experimental cancer therapies. We have three compounds being tested in cancer patients: both in the US and in the UK.

July 2008

Discovering Drugs from Bugs

Melanie McCullagh, Biotica Technology

Chris - Welcome Melanie, thank you for joining us. What are you actually up to?

Melanie - Yes, Biotica has a technology which I would say is quite the other end of the spectrum from Astex. Polyketides that are a type of compound produced naturally in soil bacteria. A lot of them are very naturally pharmaceutically active as well.

Chris - What are they?

Melanie - They’re fairly large molecules. They’re around 500 Daltons and they are made up of a series of carboxylic acids which are joined together in the bacteria by an enzyme called polyketide synthase.

Chris - What do they do?

Ball-and-stick model of sirolimus (rapamycin). Melanie - Well, we’re not completely sure what they do necessarily within the bacteria. We don’t know why they produce them per se but when we give them to humans they interact with a really wide range of targets. Some of the really famous examples, for example rapamycin, is an immunosuppressant. It’s used in transplant patients to prevent them rejecting the organ that’s been given. There are also analogues of rapamycin which are used in cancer, for example. It’s been used and tested in other indications as well. They’re more broadly applicable than that. There are antibacterial polyketides such as erythromycin. Some of the early anti-cholesterol statins were also polyketides and they’re also used in cancer. Some really novel cancer compounds which have been recently approved are also polyketide compounds.

Chris - What you’re saying is that bacteria have a pretty broad medicine chest at their disposal. All we have to do is to work out how to get it out.

Melanie - Yes, that’s right.

Chris - What are you doing to do that?

Melanie - Biotica specialises in genetically engineering the bacteria so that we can change the properties of the polyketides that are naturally produced. One really good example is there’s a polyketide called FK506 which is an immunosuppressant. It’s used in transplant patients. What we’re doing is working on that molecule to change its pharmaceutical properties, make it appropriate for delivering for example by inhalation. We can then take advantage of the fact that it down-regulates inflammation, down-regulates the immune system and give it to asthma patients. The interesting thing about FK506 is that when it’s given systemically it’s quite toxic. It has very variable metabolism. What we can do it we can change the metabolism of the drug to make it more appropriate to give in a bigger indication like asthma, really reduce the toxicity of that molecule. DNA

Chris - How do you how to tweak the DNA of the bacteria so that they make a different molecule which is more human-friendly?

Melanie - The polyketide synthase is a very interesting enzyme. The genes directly translate to different molecules within the polyketide synthase. Each of those will produce carboxylic acid and may change the acid as it’s added onto the polyketide. By looking at the genome with the bacteria we can actually identify how to change the individual modules within the polyketide synthase. For example, we can swap from one organism to another to recruit different acids into a polyketide molecule. We can tell by looking at the structure and activity relationships of the molecules that we know we can tell what changes we have to make to make changes in the activity of the molecule within the human.

Chris - Is anyone else doing this or is this your unique selling point?

Melanie - Biotica has patents on this technology. We’re the only company who is able to do certain parts of the technology. There are other companies that are doing similar things, perhaps with different types of molecules. There was another company who had some other kind of overlapping technology in the US which has recently been bought by one of the very big pharmaceutical companies.

Chris - So the bottom line here is that, rather than taking the molecule and fiddling with it chemically, you can actually take a molecule that the bacteria are already making, fiddle with the bacteria and make them make it better?

Melanie - We can get the bacteria to do the work for us. The bacteria also produce the molecules commercially as well. We can scale-up, ferment lots of bacteria and get pharmaceuticals out really efficiently.

Chris - Because bacteria don’t charge a salary and they don’t get bogged in health and safety?

Mario - Is it possible to create an intelligent vaccine or a drug that could evolve with the ever changing strains of the disease?

Melanie - That’s a very interesting question. I’m not sure that you would actually want a vaccine to evolve too much just in case once you set it loose in the wild you would risk some kind of a vaccine epidemic. I think what you can definitely do is apply selection pressure to the bacteria to change the types of molecules that they produce. That’s a similar kind of concept.

Chris - I would think that probably this is going to be big business in the future. We’re only just beginning to understand how molecules actually look. By turning this round in this way we can now start with what we want to end up with and then go back to the gene and tweak that. That’s quite a novel thing to be doing. Probably going to be a major way of doing this in the future.

Melanie - There are some real advances in technology at the moment that I think will enable us to expand greatly what we can do with genetically engineering the bacteria that produce these polyketides. Biotica’s a very small company but I think there’s a really big area for us to build into with increasingly novel technologies as things move on.

July 2008

	I’d like to know if there are any life forms: plant, animal, fungus, whatever that are effectively immortal? Geoff Blackwell, Queensland, Australia
	We spoke to Dr John Nudds, Senior Lecturer in Palaeontology at the University of Manchester to find the answer... One of the longest living vertebrate animals, and many listeners will be aware of this, is the giant land tortoise. There’s a nice story about Captain Cook, the explorer, presenting one of these animals to the queen of Tonga in 1788. This animal eventually died in 1966, 188 years later. The animal was probably mature by the time he collected it. If we turn our attention to the plant kingdom we can multiply these figures by a factor of ten. There’s a well-known example of the bristlecone pine trees which grow in the rocky mountains of North America. These are well-known to live for over 4000 years. I think the record’s about 4600 years. Again these figures have recently been doubled by research in Sweden. Scientists here came across a Norway spruce whose root system had been growing for 9550 years! If we now move onto some of the simpler life forms then the numbers do start to get really big. In 1995 a sample of bacteria was found in a stomach of a bee which was encased in amber which was dated at between 25 and 40 million years old. These bacteria were found in a state of suspended animation. They had to be reanimated in the laboratory. In scientific terms they were in what we would call a crypto-biotic state. It means the cells remained alive but none of the life processes were being carried out. They didn’t feed or reproduce so whether you consider this as immortality or not is open to question. To answer the question, the sad fact is that all cells do decompose with time. All cells age and all cells eventually die so sadly, as yet no life form has evolved that is immortal.
	July 2008
Comment on this... Hi There! I think, in fact every liveform, which reproduces only through asexual Methods is immortal. They split and split ans split and split... and all the products are based on one origin. There will be no mother cell thats getting old and dies, but two daughter cells which are living on until they split again... bye aj - atrox - 15th Jul 08 http://en.wikipedia.org/wiki/Parthenogenesis - RD - 15th Jul 08 http://en.wikipedia.org/wiki/Parthenogenesis RD - please try to include some content with an answer, rather than just links, as this is more likely to stimulate a discussion. Thanks Chris - chris - 15th Jul 08 Atrox could also be describing cloning. Parthenogenic offsping are not clones of their mother. Only clones could potentially be an immortal organism, e.g. a plant which replicates by vegetative propagation. Even then radioactivity or viruses could modify a clone's DNA creating genetic diversity. The use of the word "immortal" is highly optimistic: more than 99% of the species which have existed are extinct. Tardigrades are described in the NS article below as "indestructible", but "most resilient" would be more accurate... image source http://space.newscientist.com/article/mg16422095.100-indestructible.html - RD - 16th Jul 08 Pardon my rudeness, but that looks like a micropenis! - chris - 16th Jul 08 The shrunken dormant tardigrade above reminded me of the Clyde Auditorium... image source Images of plump tardigrades can be found here. http://tardigradesinspace.blogspot.com/ (Obviously a Dr Who fan) - RD - 16th Jul 08 How long are those tardigrades supposed to live for then? - chris - 16th Jul 08 http://en.wikipedia.org/wiki/Tardigrada http://pathfinderscience.net/tardigrades/cbackground.cfm - RD - 16th Jul 08 Another contender for the worlds hardiest organism is "Conan the Bacterium"... http://en.wikipedia.org/wiki/Deinococcus_radiodurans - RD - 19th Jul 08 Interestingly I interviewed a terrific scientist called Miroslav Radman who published a paper a couple of years back in which he explained how this bacterium manages to survive in corned beef tins that have been irradiated with a dose of ionising radiation sufficient to kill a human many times over. That's why it was called Deinococcus radiodurans when it was first identified about 50 years ago. The organism has multiple (8) copies of its genome which is uses rather like a RAID backup system. When the DNA is damaged by, for instance, ionising radiation, the intact pieces of the shattered individual genomes produce single-stranded extensions of their DNA message which links up with complementary single strands from other bits of the genome. The chances of all 8 genomes have a double strand break in exactly the same place is very low, so eventually a working copy of the entire genome is reassembled, restoring function to the organism. This single working copy is then used to regenerate the other 7 backup copies in preparation for the next brush with a corned beef can! Chris - chris - 19th Jul 08 Professor Radman working with radiation is fair example of so-called nominative determinism, these are better... Dr Bonnie Beaver, gynecologist. Lord Brain, leading neurologist. Dr Dick Chopp, urologist (specialises in Peyronie's disease). Frances Crook, director of the Howard League for Penal Reform. Lord Justice Judge, British High Court judge. Dr Looney, psychiatrist. Cardinal Sin, former Archbishop of Manila. Anna Smashnova the Israeli tennis player. Dr Weedon, urologist. . - RD - 20th Jul 08 No all earth life and indeed the whole universe is subject to relentless entropy anttend to dissapate into total disorder over time. Of course living for 10 00 years for us would be considered as immortal. But in the grand order of things absolutely impossible. Energy always morphs from hot to cold, order to disorder. We could delay death, but overcome it completely an impossibility only found as a possibility in religion - Alan McDougall - 24th Jul 08 RD "Cardinal Sin" is he the chief of all sinners, just kidding! - Alan McDougall - 24th Jul 08 The longest living clone plant is almost 5 times older that Norway spruce. It's Lomatia tasmanica, common name "King’s lomatia" named after Denny King who discovered it. It's found in Tasmania, Australia. See www.dpiw.tas.gov.au/inter.nsf/Attachments/SSKA-756W2H/$FILE/Lomatia%20tasmanica.pdf and http://www1.parks.tas.gov.au/veg/lomatia/lomatia.html. - Andrew Walsh - 30th Jul 08 I would agree with this, even if there is some change in the genetics of the sister cells, they would still be from one original cell, hence the original did not die, nor were the sister cells born. It's like a unicellular plant/animal continuing to grow by increasing the number of cells, not as one whole body, but as a dismembered body in which each cell is capable of self support and self duplication. I don't see this as cloning, but as growing. - Don_1 - 26th Aug 08 So in theory, if I take a cutting of my houseplant every 20 years and pass the new clone(s) down the generations under the same circumstances, could my plant live indefinetly? - tr1 - 2nd Oct 08 Yes, I think so. Plants such as the strawberry do this naturally. The plant can reproduce in the usual sexual manner by crosspollination, fruiting and employing the services a bird or insect to move the seed to a new location, where a new genetic plant will grow. But the plant can also reproduce asexually by growing a 'runner' which will root some 15 or more cms from the original root. This 'new' plant continues to draw its nutrition from the original root stock until the new root is capable of supporting the already developing plant. The runner then dies off and the result is two genetically identical plants. In essence, this is not a new plant, but the same plant growing a new top before it grows a new root. It is the usual method employed by strawberry producers to increase their plant stock with a plant which will produce exactly the same results year after year. The original plant from which these 'new' plants are cultivated are disposed of, since they will not produce so much fruit in their second year as they did in the first. (Taken from gardenaction.co.uk) You can see here across the center of the picture a runner from the left hand plant. It already has top growth, but has not put down any root. The plant is feeding from the original rootstock. At the top of the picture is a 'new' plant which has put down it's own root. The runner will die off to leave two separate but genetically identical plants. In fact the plant will send out a number of runners in different directions. You could say that this is the plants equivalent of moving house, or migration. The runners find a new patch of soil which, with any luck, will be more nutritious than the soil it has been drawing from for the past few months and the more 'new' plants, the better the chances of at least one of them successfully overwintering. The plant is doing what it has to do to ensure it's survival. This process goes on year after year, the original plant, therefore, never truly dies, it merely takes up a new residence. - Don_1 - 2nd Oct 08 I'm honestly surprised that no one has brought up HeLa cells (immortal cancer cells that many labs have used for research). Yes, they aren't technically alive in the normal sense of the word but the cancer cells can divide an unlimited number of times without any signs of stopping. - ouabache - 3rd Oct 08 An old topic, but I found something quite interesting that is relevant. Apparently, there is a species of jellyfish called Turritopsis nutricula that is, in theory, immortal. The sexually mature medusa form of the species can actually revert to the sexually immature polyp stage. I guess it can then transform back into the medusa stage and continue the cycle indefinitely (as long as it can find food and avoid being killed, that is). http://8e.devbio.com/preview_article.php?ch=2&id=6 - Supercryptid - 18th Dec 08 Not found yet,although slight change in definition of "life" may let us include microbes and virus in the list. - ramtarun - 22nd Dec 08 i'd just read a book about the quantum physics and some other theories concerning about that, i read an interpretation called 'Many-worlds interpretation'(also known as 'parallel universe theory', 'multiverse'). http://en.wikipedia.org/wiki/Many-worlds_interpretation If that is true, then human (who have consciousness) are basically immortal. Because if you are dead, your consciousness will be basically shifted to another 3-dimension and in that another 3d world, you experience the probability of not dying. - johnson039 - 23rd Dec 08 Some are, perhaps? Don't really know, but a very good question... Awh sorry, read the banner again. ' Are any organisms immortal? ' Thought it said ' Are any orgasms immoral?' My fault, need glasses, or a 'cleaner' mind? Probably both:) - yor_on - 26th Dec 08 Just for fun, let's add the spiritual to the question 'are some life forms immortal?' As usual, a state of self-consciousness has to be a part of the question when the spiritual realm is added... When the biological entity dies and 'goes the way of all flesh' and returns to dust, is there a post-mortal consciousness that persists beyond the mortal body? If so, then the original question of effectively immortal becomes more speculative when taken beyond this mortal coil. So here is another questions: Do human clones have separate souls? Of course the answer is yes, cf. identical twins as separate but equal. Do self-conscious animals (gorillas, dogs, grey parrots, elephants, humans, etc) have souls? Self-consciousness doesn't necessarily imply souls, I think. And yet, the last great commandment made by Jesus before his Ascension was to preach the gospel to every creature. Why, if souls are only for humans? Do dogs go to heaven? Well, heaven without dogs, cats, etc would not be much of a heaven for me. - Freeholder - 30th Dec 08 Hybridomas, although not entire organisms, are essentially immortal. They are myeloma cancer cells that are fused with plasma cells and are used in creating monoclonal antibodies for use as reagents. - darkmartheight - 3rd Jan 09 What about hydra? AFAIK there is no increase in mortality with age. There's also that jellyfish which can revert to a younger state. HeLa cells might count too. - Anonymous - 26th Feb 09 Yes, those darned Jellyfishes again. First they take over the oceans, and then us. It is time we took a stand there. - yor_on - 26th Dec 09 You know I quite like this kind of stand Can we take some over there?? - Chemistry4me - 26th Dec 09 Will you be the conductor? Waltzing the jellyfishes to extinction? Anyway, I'm not sure I would like that last one, they seem to be amazing creatures. Soon they will learn to communicate too. "Take me to your leader." - yor_on - 26th Dec 09 First of all, nothing at all is immortal, and accordingly, the terminology must be reduced to 'long lasting'. After all, the sun will eventually die. In addition, I would exclude clones as a form of long lasting life. They are nothing more then recreated or reproduced life that has already or will soon die a separate death. It simply does not matter the genetics are the same. An arguement might be made that certain Myceleum are long lived. However, I have yet to see a C14 dating of any long lived mycelium. This is probably because none of the living culture is old enough to measure, and qualifies mostly as a clone. The longest lasting continuous life I am aware of is the Bristle Cone Pine. These are simply small shrub trees that live, well, who knows. Certainly many millenia. Dendrochronologists have cross referenced dead ones to living ones and spanned, I believe, something like 8,000 years. Still, the really old ones have been dead a very long time. - litespeed - 5th Jan 10 The bristlecones are indeed the oldest living trees. There are trees at least 4300 years old. The publicly shown trees are that old. There are trees in the 4800 year old range that are not revealed to the public. Other old trees include the giant sequoia. These trees are old and appear to die from falling over before they die of old age. Some colonial plants are also old. The creosote bush of the American Southwest can live to over 11,000 years. A spruce in Sweden was just under 10,000 years. It too is colonial. Some colonial organisms may be 80,000 years old or older. - stereologist - 5th Jan 10 stereologist Fascinating. However, I googled colonial organisms and they seem to fall into the clone category. I am especially interested in the Swedish spruce you mentioned. Does it continuously propogate from root stock? Did they do a core sample to determine its age? If we count colonial organizms, Stromatolites might conceivably be millions of years old. They seem to be one of the few 'organisms' that survived 'Ice Ball' earth, and are still found in Australia. They are also the oldest form of fossil a collector can buy. Apparently because they were the only life form available for fossilization at the time. However, none of the individual living cells are that old. They simply replace one after the other over long periods of time, leaving behind an accumulation matrix of whatever it is they excrete. I think it would be really neat if someone could compare current stromatolite DNA with the ancient ones. I general, I would like to see DNA analysis of long lived clones to observe if random mutations take place, and at what rate. Could a mutated clone still be considered the same life form. Or would it be counted as establishing a new line of clones. Lots of fun.... - litespeed - 5th Jan 10 All living creature have to die. Nothing is immortal. The creature like amoeba is immortal, cause it reproduce through binary fission. Among plants mostly those which reproduce through vegetative propagation rarely comes to existence. - mystyle - 27th Jan 10 Physical immortality is antithetical to sexual biology and the process of evolution. While immortality may sound great from an individual ego-based standpoint, it would represent an eventual death sentence for the human race. Our race, and indeed any sophisticated organism on Earth, uses evolution as a means to react to the changing environment and insure species survival. Random genetic experiments crop up in every generation. Most convey no advantage or are an active detriment to survival. As such, the alterations eventually disappear from the genome. However, periodically a genetic mutation gives the inheritor an important advantage which allows it to mate and spread the new genetic variant. Thusly, life faces the trials and tribulations that are present on our ever changing planet! PLEASE REMEMBER! The survival of any individual animal or plant is of no significance in the Grand Universal scheme of life. We're in it for the species, children! Immortality would undoubtedly place any such cursed species at a major evolutionary disadvantage. Even assuming sterility wasn't a side effect of a substantially extended or immortal lifetime, it's well known that longer lived life forms have fewer offspring space further apart. Fewer offspring means substantially lengthened time between generations and inhibits any organism's ability as a species to react to changes in the environment, new diseases etc. Indeed, many of the species that have gone extinct in the last 100 years fall into this slow-adaptor category. They just couldn't evolve fast enough to cope with the rapidly changing environment caused by humanity and our spread across the globe. The polar bear is probably doomed for instance, but I wouldn't wait around for the house fly or mosquito to follow suit! There's a reason scientists like using fruit flies and mice for genetic experiments. One of these reasons is how fast they multiply and evolve in responses to their environment. In fact, if it ever came down to a wager, I'd place money on the fruit flies, mice, and the infamous cock roach on outlasting homo sapiens sapiens as a species any day of the week! Yes, millions of these tiny individuals die every day, but their rapid evolution promotes their survival as a healthy species. Lastly, of course, would be the ghastly societal effects of widespread human immortality. Starvation, war, and social and economic anarchy would be the inevitable result. For the sake of humanity, let's keep physical immortality in the realm of science fiction and vampire movies and TV shows! The horror of these programs should be sufficient for anyone! - Rick - 7th Mar 10 See the whole discussion \| Make a comment

	You mentioned earlier that we measure things in Daltons. What actually is a Dalton? Andrew, Cambridge
	We put this question to Dr Harren Jhoti: Harren - Basically a Dalton is just a measure of weight, it’s a measure of mass. It’s a very, very small measure of mass: something like micrograms or grams people refer to but at a kind of microscopic level, if you like. Daltons are basically very single units of small mass. Chris - So when you’re down at the molecular level you can’t use grams or even thousandths of grams? You need to use much smaller molecular units. Harren - That’s exactly right. That’s the most commonly-known unit which people refer to when looking at small molecules.
	July 2008

	Different people react differently to different drugs. Would you say there are different body types in the population and therefore should we be looking for them? Pooky Amsterdam, Second Life
	We put this question to Dr Harren Jhoti: Harren - Yes, I think this is a very interesting question. It really touches on what’s happening in a broader sense in the pharmaceutical industry. People are really talking about personalised medicine. This issue that body types or different types of people, often due to their different genotypes or genetic make-up - it’s going to be very interesting to see how drugs actually are metabolised by different types of people and whether those drugs show different levels of efficacy in different types of people. There’s a huge push in the industry now to see whether we can’t try to predict up front by reading the genotype of a particular person and whether that person is going to a) respond to the particular treatment and b) whether they’re going to have a higher chance of having detrimental side-effects due to some toxicities. There’s a big push in this whole personalised medicine. It’s based on body types and genome sequencing. It’s all part of the same issue. Chris - It’s very interesting, isn’t it. If you go into a shoe shop you expect to get a pair of shoes that’s the right size for you. But you go into a chemist and you’re given a drug which millions of other people take and it’s expected t o fit your molecules in your body just perfectly even though you might be totally different from the next person. Harren - Yeah. That’s a reality today because we simply haven’t had the technologies to be able to segregate people into these different groups. Genome sequencing is a very recent development and many of these drugs were actually discovered and developed ten or fifteen years ago. I think going forward molecularly-targeted agents which try to target subgroups of patients is going to be very much the focus.
	July 2008

	How do you train antibodies to attack skin cancer? Rolly Mandlebrot, Second Life
	We put this question to Dr Melanie McCullagh: Melanie - Monoclonal antibodies are a very interesting new way of treating cancer and one of the really clever things about them is that they target specific receptors on the surface of the cancer. What we know about antibodies is that their structure is like a lock and key. They fit very closely onto the receptor and are very specific to where they take the activity of the antibody. In melanoma, which is a particularly serious form of cancer with some really quite poor outcomes, there’s some really great work going on at the moment looking at making the antibodies target those receptors much more specifically and much more clearly to the cancer itself. Chris - Do you see this as being a massive growth area now? Are we going to see people that are better at doing this in future? Melanie - I think it’s really important and there’s a lot of companies working on how to develop new forms of antibodies with a greater specificity for cancer but also with different types of activities. Even ones that can carry other cancer therapeutics directly to the site of the tumour, which is very interesting. Chris - It’s very important too since one person in every three will ultimately in their lifetime die of cancer.
	July 2008

	Is it possible to create an intelligent vaccine or a drug that could evolve with the ever changing strains of the disease? Mario
	We put this question to Dr Melanie McCullagh: Melanie - That’s a very interesting question. I’m not sure that you would actually want a vaccine to evolve too much just in case once you set it loose in the wild you would risk some kind of a vaccine epidemic. I think what you can definitely do is apply selection pressure to the bacteria to change the types of molecules that they produce. That’s a similar kind of concept. Chris - I would think that probably this is going to be big business in the future. We’re only just beginning to understand how molecules actually look. By turning this round in this way we can now start with what we want to end up with and then go back to the gene and tweak that. That’s quite a novel thing to be doing. Probably going to be a major way of doing this in the future. Melanie - There are some real advances in technology at the moment that I think will enable us to expand greatly what we can do with genetically engineering the bacteria that produce these polyketides. Biotica’s a very small company but I think there’s a really big area for us to build into with increasingly novel technologies as things move on.
	July 2008
Comment on this... mario asked the Naked Scientists: Is it possible to create an intelligent vaccine or drug that can evolve with ever changing strains of disease? Is it possible to screen someone's genome to identify mutations that could to predict how someone may react to a drug or indicate if they have immunity against certain diseases? Current drugs/treatments are aimed at killing or eliminating threats, or familiarising our immune systems so they are prepared to defend against pathogens. This strategy is clearly becoming ineffective in light of new more virulent strains of disease (eg MRSA, XDR-TB). We always seem to be one step behind. What do you think? - mario - 15th Jul 08 Personally, I think what you suggest may well be possible, if a long way off. - LeeE - 15th Jul 08 I'm not so sure; bacteriophage therapy (viruses that selectively kill bacteria) is making a comeback: http://www.thenakedscientists.com/HTML/articles/article/virusesvssuperbugs/ As phages are controlled by the same nucleic acid chemistry from which the genomes of these pathogens are constructed, then the phages will evolve with the infection. Chris - chris - 16th Jul 08 See the whole discussion \| Make a comment

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