Averaging photos creates infallible face recognition tool

Compare a photo of yourself all cleaned up for a night out with another one first thing the next morning, and you’ll begin to appreciate the problems that people working on face recognition software encounter.

While some unfeasibly lucky people look great from all angles, most of us have to contend with a lottery of lighting conditions, odd angles, stupid expressions, stupider poses and the ravages of age. Faced with this unavoidable variability, it’s no wonder that automatic software flounder when tasked with comparing images to stock photos, like those in passports.

Now, Rob Jenkins and Mike Burton from the University of Glasgow have beaten the problem by creating a face recognition system that, so far, has proved to be 100% accurate. This level of accuracy is unheard of in the technological world. It is matched only by that most sophisticated of computers – the human brain – and indeed, it’s the brain that provided Jenkins and Burton with the inspiration for their method.

Canny breeding creates vitamin A-rich maize without genetic modification

On Thursday, I wrote about a way of genetically modifying carrots to turn them into rich sources of calcium. The method could be more widely used in vegetables to help reduce nutritional deficiencies, but it risks raising the ire of the anti-GM environmentalist camp. But there is another way of altering the genes of crop plants that avoids such controversy, and it’s a traditional one – selective breeding.

By cross-breeding individuals with desirable qualities, farmers have been tinkering with the genes of both animals and plants for centuries. Traditionally, the process has been a bit messy. Genes don’t always easily translate into physical characteristics, so there is a certain amount of trial-and-error involved.

Now, Carlos Harjes from Cornell University had developed a way of using modern genetic techniques to make selective breeding even more selective. For his first trick, he has developed a variety of maize to combat vitamin A deficiencies. Best of all, no genes were added, tweaked or subtracted in the making of this vegetable – he only used the natural genetic variation within the world’s maize strains.

Meet the genetically modified super-carrot, now fortified with calcium

For centuries, mothers have wrongly told their children that eating carrots will improve their vision. The sight-enhancing properties of these iconic vegetables is be a myth (albeit a fascinating one involving Nazis and fighter pilots) but if Jay Morris has anything to say about it, they may soon be better known for building strong bones.

Morris, together with Kendal Hirschi and other Texan colleagues, has found a way to double the calcium content of carrots through genetic modification, making them a rich source of the element that is so vital for bones

The team loaded their super-carrots with a protein called sCAX1, which pumps calcium into the plant’s cells. The protein originally hailed from the plant-of-choice for geneticists, Arabidopsis thaliana, where it exists in a larger version. Morris’s team lopped off a small piece from its tip that stops the protein from funnelling in more calcium once a certain amount has been reached.

In this shortened form, sCAX1 is relentless in its import of calcium and the researchers have found that it can greatly increase the calcium content of several vegetables including tomatoes, potatoes and carrots. These super-charged vegetables could help to reduce the risk of osteoporosis, one of the world’s leading nutritional disorders, where a lack of calcium leads to brittle bones.

The effect of GM crops on local insect life

A large study weighs up the existing evidence on the impact of GM crops on local insect life, providing some much-needed scientific rigour to the GM debate.

In Europe, the ‘GM debate‘ about the merits and dangers of genetically-modified (GM) crops is a particularly heated one. There is a sense of unease about the power of modern genetic technology, and a gut feeling that scientists are ‘playing God’. These discontents are stoked by the anti-GM camp, who describe GM crops with laden and fear-mongering bits of unspeak like ‘Frankenstein foods’ and ‘unnatural’.

In a debate so fuelled by emotion and personal values, scientific research and a critical analysis of the evidence rarely gets a look-in. But science has to grudgingly admit some blame in this, because there is actually precious little research on the safety of GM crops. And many of the studies that have been done were short-term and poorly replicated.

A lack of research is dangerous. It provides opening for people on either side of the debate to quote single, small studies as canon and brushing aside any research that contrasts with their stances.

Adding evidence to the debate

Michelle Marvier and colleagues from Santa Clara University, California, are trying to change all that. They have analysed over 42 field experiments on GM crops to get an overall picture about their safety. The technique they used is called meta-analysis, a statistical tool that asks “What does everyone think?” It works on the basis that individual small studies may be far from conclusive, but pooling their results together can lead to stronger and more accurate results.

They looked at three strains of GM-crops that had been modified with genes from a soil-dwelling bacterium called Bacillus thuringiensis. The transferred genes are responsible for producing a number of biological (and therefore ‘natural’) insecticides. When moving them across to plants, geneticists typically try to match the insecticide to the pest they are trying to fight. (In the image on the right, Bt-peanut leaves are protected from the damaging European corn borer)

The toxins are delivered at high dosages to pests, but are restricted to the plant (and sometimes even to particular tissues). They can also be added to the chloroplast genome, which is quite separate form the plant’s nuclear DNA. This stops them from being transferred to other plants.

The hope is that these so-called ‘Bt crops’ can help to minimise the collateral damage of less targeted insecticide sprays. In theory, only pest insects that eat valued crops are killed, while the rest of the ecosystem is unharmed.

The results

That’s what Marvier set out to test. She looked at field experiments which tested the impact of caterpillar-resistant cotton and maize plants on the abundance of other groups of insects and invertebrates.

She found that these other creatures are found in greater numbers in fields containing the caterpillar-resistant GM plants, compared to those sprayed with conventional insecticides. However, the GM crops also led to slightly lower numbers of non-targeted insects compared to fields where no GM crops and no insecticides were used.

The results stayed the same even when Marvier analysed them in more detail. For example, she found much the same thing when she only looked at experiments that had been published in peer-reviewed scientific journals.

So assuming that Bt crops do indeed reduce the use of insecticides (and that’s far from proven), then they will also, as claimed, reduce the collateral damage caused by these chemicals. But they’re not as good for the environment as using no insecticides at all, be they engineered or sprayed.

The bigger picture

At the local level, Marvier’s study provides some much-needed scientific backbone to the GM debate. But the real decisions need to be weighed up at a larger level. For example, it’s all well and good to say that a no-insecticide, no-GM field is the best solution, but that leaves farmers in a bit of a lurch.

One of the big criticism levelled against organic farming is that it leads to lower yield than other practices and requires more agricultural land to be viable and that deals a bad hand to farmers in the developing world. This in turn could lead to deforestation and habitat loss.

On the other hand, Marvier advises caution when interpreting her work. This study has revealed just one benefit of GM crops and even then, only for one specific type of genetic modification. Many of the studies involved isolated patches of land, rather than entire farming systems, where the situation is more subtle. Not all non-GM crops are sprayed with insecticides, while not all GM crops are free from them.

Any benefits must also be weighed against potential health or environmental risks, and again, these must be researched carefully.

To Marvier, the clearest message from her study is that we have started to accumulate enough data to look at this issue from an empirical, evidence-based point of view. If we are to make sound decisions, there is little room for anecdotal evidence or knee-jerk responses guided by personal philosophy.

Bt hypocrisy

For example, there is a certain irony to the opposition to Bt crops. Because its insecticides are ‘natural’, the bacterium is one of the few pesticides that organic farmers are allowed to spray onto their crops.

The bacteria of course use the exact same genes that are transplanted into Bt-engineered crops. Some may argue that this method is better because it is more ‘natural’, because the genes stay within the organism they were intended for. But is that really better?

Wholesale Bt spraying is a crude technique than the specific and targeted use of Bt-engineered crops. It means that the surrounding land is also covered in the bacteria and creatures other than pests are exposed to its entire gamut of toxins. And because farmers need constant supplies of the bacteria, it soaks up more money.

Reference: Marvier, McCreedy, Regetz & Kareiva. 2007. A meta-analysis of effects of Bt cotton and maize on nontarget invertebrates. Science 316: 1475-1477.

Technorati Tags: GM crops, genetic modification, GM safety, GM environment, GM debate, insecticides, Michelle Marvier, Peter Kareiva, Bt crops,

Related stories on genetic modification:

Genetically-modified mosquitoes fight malaria by outcompeting normal ones
Magnifection: mass-producing drugs in record time
Feed the world – turning cotton into a food crop

Sneaking medicines past the brain’s defences

The brain is surrounded by a protective barrier designed to keep infections out. But it can also block out medicines intended to treat brain diseases. Now, scientists have developed a way of sneaking helpful proteins across the barrier by giving them fake molecular ID.

Using genetic engineering, a group of scientists have developed a way of sneaking a virus past the brain’s defences. Don’t panic – this isn’t some nightmare scenario. It could be the first step to curing a huge number of brain diseases.

The brain seems incredibly well protected amid its shell of bone and cushioning fluid. But even the strongest of forts needs supply lines, and brain is no exception.

A dense network of blood vessels carries vital oxygen to its cells. These vessels are a potential vulnerable spot, providing access for bacteria and other disease-causing organisms to migrate in from other body parts.

But even these weak spots are heavily guarded. The blood vessels in the brain are lined with a tightly packed layer of cells that restrict the flow of molecules from blood to brain. These cells form a protective shield called the blood-brain barrier, or BBB.

It is a superb defence but it can do its job too well. Not only does it block out dangerous microbes, but it can also exclude large proteins and drugs designed to treat brain diseases. Usually, these large molecules need to be distributed throughout the entire brain to be effective. With the BBB in the way, they don’t stand a chance.

Now, Brian Spencer and Inder Verma from the Salk Institute of Biological Studies have come up with a way to disguise helpful molecules to sneak them past the brain’s defences.

Their method exploits special gates in the barrier that control the import of essential nutrients and molecules like cholesterol into the brain. These molecules are escorted by a large protein called apoliprotein B (apoB), and are presented to sentinel proteins that guard the gates.

One of these guardians, called LDLR, is designed to recognise a specific segment of apoB. Once it has confirmed the visitor’s identity, it escorts apoB and the molecules it accompanies through the barrier. The whole system works with the tight control of a maximum security prison.

Spencer and Verma managed to fool the system. They took the part of apoB that is recognised by LDLR and stuck it to various proteins, giving them the molecular equivalent of a fake pass.

First, they tested their method in mice. They injected the animals with a harmless virus designed to travel to its liver and spleen. There, the virus sets about building the disguised protein, which is secreted en masse into the bloodstream.

The beauty of this method is that it works after a single injection that transforms the liver and spleen into factories for the protein of choice.

Their first candidate was GFP, a jellyfish protein that glows in the dark with a greenish hue, allowing it to be easily tracked. Sure enough, the injected mice soon gave off a greenish glow from their brains and the rest of their central nervous systems.

Better still, their method showed real practical potential by sneaking an enzyme called glucocerebrosidase (right) into the brain. Glucocerebrosidase is vital for the storage of fats. People who lack it suffer form a condition called Gaucher’s disease, where fatty desposits collect on various organs and cause brain damage, among other symptoms.

The disease is relatively easy to fix using regular injections, but the resulting brain damage is not for the injected enzyme is usually repelled by the blood-brain barrier. But Spencer and Verma’s method may change all that.

The duo fully admit that their work is merely a first step, but it is an important one nonetheless. The technique must first be refined and tested in people before it can be widely used. Developing drugs and proteins for treating brain disorders is pointless if those new medicines just congregate uselessly outside the blood-brain barrier. Spencer and Verma may have given them a way in.

Reference: Spencer & Verma. 2007. Targeted delivery of proteins across the blood-brain barrier. PNAS 104: 7594-7599.

Technorati Tags: Blood brain barrier, drug delivery, brain treatments, LDLR, apoliprotein B, science

Genetically-modified mosquitoes fight malaria by outcompeting normal ones

Genetically-engineered mosquitoes that are resistant to the malarial parasite could be the key to reducing the burden of malaria. In laboratory experiments, they are stronger and fitter than their normal peers and rapidly dominate the population.

Fighting malaria with mosquitoes seems like an bizarrely ironic strategy. But that’s exactly what many scientists are trying to do.

Malaria kills one to three million people every year, most of whom are children. Many strategies for controlling it naturally focus on ways of killing the mosquitoes that spread it, stopping them from biting humans, or getting rid of their breeding grounds.

But the mosquitoes themselves are not the real problem. They are merely carriers for the true cause of malaria – a parasite called Plasmodium. It suits neither mosquitoes nor humans to be infected with Plasmodium, and by helping them resist it, we may inadvertently help ourselves.

With the power of modern genetics and molecular biology, scientists have produced strains of genetically engineered mosquitoes that cannot transmit the malarial parasite.

These ‘GM-mosquitoes’ carry a modified gene – a transgene – that produces chemicals which interfere with Plasmodium’s development. Rather than becoming suitable carriers, the modified mosquitoes are death for any invading Plasmodium.

But scientists can’t very well change the genes of every mosquito in the tropics. To actually reduce the burden of malaria, the genetic changes that induce malaria resistance need to be spread throughout the mosquito population. The easiest way to do this is, of course, to let the insects do it themselves.

And Mauro Marrelli and colleagues from the Johns Hopkins University have found that they are more than up to the task.

They kept cages full of equal numbers of engineered and normal mosquitoes and fed them on the blood of mice infected by Plasmodium. After nine generations, they found that the engineered insects had become proportionally more common, making up about 70% of the total population.

Like most parasites, Plasmodium affects the health of its host. So mosquitoes that are parasite-resistant are stronger and fitter than their infected peers. Marrelli found that they were about 25% less likely to die early, and had more young, with every female laying an average of 60 eggs compared to 43.

With these advantages, the transgenic mosquitoes outlasted and out-bred normal ones, and quickly established a majority in the population.

But if the advantages to resistance are so great, why haven’t naturally-resistant mosquitoes replaced non-resistant ones? Other studies have shown that resistant mosquitoes fight off Plasmodium with the help of hyperactive immune systems, but have no evolutionary advantages over carriers.

Marrelli thinks that because chronic immune responses produce health problems of their own, that cancel out the advantage of not carrying Plasmodium. In contrast, the transgenic mosquitoes are simply expressing a gene that is mostly harmless. The gene also kills Plasmodium early on in its life cycle, well before it triggers the body’s own immune system.

Even though a single transgene copy does not affect the modified insects’ health, it appears that two copies might have some as-yet-unknown health consequences. This may explain why the resistant mosquitoes in Marrelli’s experiments did not totally dominate the population, but plateaued at 70%. The strongest mosquitoes are those with just one copy of the gene.

This means that introducing the engineered mosquitoes into the wild would not completely wipe out their disease-spreading cousins. But it would still drastically cut their numbers. Considering that malaria infects over 400 million people a year, reducing this number by 70% would be a monumental victory for international health.

Nonetheless, Marrelli is cautious about the future of malaria-resistant strains. These experiments are a proof-of-principle and their results may not bear out as planned in practice.

In the field, only a relatively small proportion of mosquitoes become infected, and he expects the spread of the transgene to be slower. But if it becomes established, it could complement other programmes for controlling malaria, by making it very hard for the parasite to re-colonise a cleared area after it has been eradicated.

 

Reference: Marrelli, Li, Rasgon & Jacobs-Lorena. 2007. Transgenic malaria-resistant mosquitoes have a fitness advantage when feeding on Plasmodium-infected blood. PNAS 104: 5580-5583.

Images: Plasmodium image by Ute Frevert

Technorati Tags: malaria, mosquitoes, genetically engineered, GM, genetic engineering,

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Salamander robot walks, swims and sheds light on evolutionary step from sea to land

A team of scientists have developed a robot salamander that walks and swims using an electronic spinal cord. The robot provides us with clues about how our ancestral animals made the evolutionary leap from the sea to the land.

Moving robots are becoming more and more advanced, from Honda’s astronaut-like Asimo to the dancing Robo Sapien, a perennial favourite of Christmas stockings.

But these advances are still fairly superficial. Most robots still move using pre-defined programmes and making a single robot switch between very different movements, such as walking or swimming, is very difficult. Each movement type would require significant programming effort.

But robotics engineers are now looking to nature for inspiration. Animals of course, are capable of a multitude of different styles of movement. They have been smoothly switching from swimming to walking for hundreds of millions of years, when our distant ancestors first invaded the land from the sea.

This ancient pioneer probably looked a fair bit like the salamanders of today’s rivers and ponds. On the land, modern salamanders walk by stepping forward with diagonally opposite pairs of legs, while its body sways about its hips and shoulders. In the water, they use a different tactic. Their limbs fold back and they swim by rapidly sending S-like waves down their bodies.

Both of these movements, as in all back-boned animals, are controlled by bundles of neurons called central pattern generators (CPGs). These bundles run down either side of the animal’s spine (its body CPG) and in each of its four limbs (its limb CPGs).

The CPGs produce rhythmic movements in muscles, by sending them carefully timed pulses of electrical signals. The brain is a casual bystander in this process, stepping in only to tell the CPGs to switch from a walking to a swimming rhythm, or vice versa.

By directly stimulating the brains of salamanders, Jean-Marie Calguen from the University of Bordeaux, managed to trigger the switch between walking and swimming gaits. With low levels of stimulation, the hapless animal made walking movements, and at higher levels, it tried to swim.

Calguen, along with Auke Ijspeert from the Ecole Polytechnique Federale de Lausanne, came up with a model for how this switch works and tested it by building a robot salamander. The metre-long and grandiosely named Salamandra Robotica was designed to mimic its biological counterpart.

Its movements are controlled by an ‘spinal cord’ that uses electronic CPGs to control its body and limbs. Like a real salamander, these are overseen by signals from the robot’s ‘brain’ – in this case, a wireless human-controlled laptop.

Ijspeert and Calguen used different CPG programs to control the robot’s body and limbs. When the robot receives any stimulation from its laptop brain, its body CPG produces the S-like body waves used by swimming salamanders.

At low levels of stimulation, the limb CPGs overpower the bodily ones, and the robot walks. But the limb CPGs cannot cope with higher levels of stimulation and switch off, leaving the bodily CPG free to start a swimming motion.

This model was a success. When they tested Salamandra Robotica on the shores of Lake Geneva, Ijspeert and Calguen found that their robot reproduced the same swimming and walking gaits seen in living salamanders, abruptly switching between the two depending on how much stimulation its CPGs received.

The model shows one way in which evolution could have modified an aquatic animal’s movements to a walking way of life. This was a key evolutionary step and provided the impetus for the spread of life from sea to land.

Salamandra’s success also shows that the studies of robotics and biology can successfully work together. Robots can be used to test biological ideas, while biology in turn can inspire successful solutions to engineering problems.

The robot salamander is part of a new era in robotics, where robot movements are controlled by artificial nervous systems.

 

Reference: Ijspeert, Crespi, Ryczko & Cabelguen. 2007. From swimming to walking with a salamander robot driven by a spinal cord model. Science 315: 1416-1419.

(Salamander photo by Marek Szczepanek. Photo of Salamandra Robotica from EPFL. Drawing of Acanthostega by Arthur Weasley.)

Technorati Tags: evolution, invasion of land, salamanders, salamander robot, robotics, artifiical nervous systems, walking, science

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Feed the world – turning cotton into a food crop

The world’s cottonseed harvest have enough protein to feed half a billion people in the world’s poorest places, but are inedible because they contain a potent poison. Now, scientists have found a way of removing that poison, and turning cotton into a stunning new food source.

 

“Feed the world. Let them know it’s Christmas time.” The world is currently home to 6.5 billion people and over the next 50 years, this number is set to grow by 50%. With this massive planetary overcrowding, Band Aid’s plea to feed the world seems increasingly unlikely.

Current food crops seem unequal to the task, but scientists at Texas University may have developed a solution, a secret ace up our sleeves – cotton.

Cotton is famed for its use in clothes-making and has been grown for this purpose for over seven millennia. We do not think of it as a potential source of food, and for good reason.

The seeds of the cotton plant are rife with a potent poison called gossypol (see below) that attacks both the heart and liver. Only the multi-chambered stomachs of cattle and other hooved animals can cope with this poison, relegating cottonseed to a role as animal feed.

Getting rid of gossypol could go a long way to reducing the world’s hunger crisis. A fifth of a cottonseed’s weight is made up of oil, and a quarter of high-quality protein. For every kilogram of fibre, each cotton plant produces 1.65 kg of seed.

And the plant is grown in over 80 countries by some 20 million farmers, the majority of whom live in the poorest parts of the world, where starvation is an ever-looming threat. If only the seeds could be made edible.

In 1954, scientists attempted to launched a programme to cross-breed normal cotton plants with a mutant strain that lacked the glands that make gossypol. Unfortunately, they discovered that cotton creates the poison for a reason.

It infuses the plant’s various tissues, protecting it from insect pests and infections alike. The programme’s seeds were safe for human consumption, but the weakened plants readily succumbed to insect attacks, destroying their commercial potential.

Now, Ganesan Sunilkumar and colleagues have solved the problem. They have used a technique called RNA interference, or RNAi, to turn off a gene called delta-cadinene synthase, which is essential for gossypol production.

But in this case, the team put their system under the control of a genetic switch used only in cotton seeds, and not the rest of the plant. As a result, levels of gossypol plummeted in the plant’s seeds and these alone. The rest remained as strong as ever against attackers.

Sunilkumar ran their special plants through a series of tests to make sure that the RNAi’s effects never spread to the rest of the plant. They passed every one. Best of all, the altered plants stably passed on their characteristics to their daughters.

This study is testament to both the power and the precision of modern genetic technology. The researchers identified a very specific point in a biochemical pathway and blocked it in a single part of the plant. The result is a variant that retains the original’s survival abilities, but is suddenly fit for human consumption.

Their approach has tremendous potential for opening up other food sources. For example, the beans of the tropical grass pea, Lathyrus sativus, are often eating by poor people in Africa and Asia in times of dire need.

As the beans contain a potent neurotoxin – a nerve poison – those eating them often contract a neurological disease called lathyrism. With Sunilkumar’s technique, lathyrism could become a thing of the past.

For those who feel that the use of such technology is tantamount to playing God, consider this. Every year, 44 million tons of cottonseed are wasted. With this new technology, the engineered seed could provide enough protein for half a billion people every year.

Sunilkumar, Campbell, Puckhaber, Stipanovic & Rathore. 2006. PNAS 103: 18054-18059.

Technorati Tags: cotton, gossypol, food shortages, famine, world hunger, genetic engineering, GM crops, RNAi, science

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New learning robot adapts to injuries

The field applications of modern robots are limited because they are largely unable to cope with damage and injuries. But a new robot called Starfish could change all that – it is programmed to learn about itself and adapt to new situations, with no pre-built contingency plans.

I am walking strangely. About a week ago, I pulled something to my left ankle, which now hurts during the part of each step just before the foot leaves the ground. As a result, my other muscles are compensating for this to minimise the pain and my gait has shifted to something subtly different from the norm.

In similar ways, all animal brains can cope with injuries by computing new, often qualitatively different, movements to compensate. Because this isn’t a conscious process, we often take it for granted. But by looking at how difficult it is to program a robot to do the same thing, we can get a sense of how hard it actually is.

Robots have been used for years to perform structured, repetitive tasks. As engineering has advanced, their movements have become more and more stable and life-like.

But they still have severe limitations, not the least of which is inflexibility in the face of injury or changes to its body shape. To put it simply, if a robot’s leg falls off, it becomes as useful as so much scrap metal.

So for robots, adaptiveness is a desirable virtue. Modern bots can independently develop complex behaviours without any previous programming but this requires trial and error and lots of time.

Josh Bongard and colleagues at Cornell University , New York, have solved this problem by developing a robot (see right; image from Science magazine) that continuously assesses its body structure and develops new ways of moving if anything changes.

It differs from other models in that it has no built in redundancy plans, no strategies for dealing with anticipated problems. It’s simply programmed to examine itself and adapt accordingly.

The concept of a robot that can adapt to new situations is often the precursor to nightmare scenarios in many a science-fiction film. So it is fortunate that Bongard’s robot isn’t armed or threatening, but instead looks more like a four-armed starfish.

Each arm has two joints, and sensors that record the angle of these joints, and the tilt of the arms.

At first, Starfish performs some experiments. Humans have an instinctive understanding of how our body parts connect with each other, but this sense, called kinaesthesia, must be programmed into robots. Bongard’s robot doesn’t need that – it can work out its structure on its own.

It does this by performing random actions and using an array of sensors to see what these do to its body. It then creates several ‘self-models’ – representations of how its body is joined together – in the same way that a forensic scientist pieces together how a crime occurred based on the evidence.

Starfish then compares the models and performs actions designed to distinguish between them. After several rounds of this, the robot has a fairly accurate idea of how it’s built, what sorts of things it can do, and which parts it needs to move to do them. If it’s given an instruction, such as ‘move forward’, it can plan the best way of doing that.

However, the robot detects something funny that goes against its self-model, it initiates the whole process again. If it’s leg falls off, it notices, re-creates its picture of itself, and plans new behaviours to cope with its new situation.

These abilities will be instrumental in the future of robotics. Robots will become exponentially more useful if they can respond to new environments, or cope with the bodily changes that happen when they grasp a tool or suffer damage.

They can be deployed to unstable disaster sites to help with recovery, or to the depths of space for exploration. They may even give us an insight into how the human brain develops self-awareness and adapts to new situations.

Bongard, Zykov & Lipson. 2006. Science 314: 1118-1121.
Technorati Tags: robotics, learning robot, artifical intelligence, robots, science

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Carbon nanotechnology in an 17th century Damascus sword

The Damascus swords of the Middle East were legendarily sharp, strong and flexible. Now, an analysis of one of these weapons under an electron microscope reveals that the key to its properties is nanotechnology, inadvertently used by blacksmiths centuries before modern science.

In medieval times, crusading Christian knights cut a swathe through the Middle East in an attempt to reclaim Jerusalem from the Muslims. The Muslims in turn cut a swathe through the invaders using a very special type of sword, which quickly gained a mythical reputation among the Europeans.

These ‘Damascus blades’ were extraordinarily strong, but still flexible enough to bend from hilt to tip. And they were reputedly so sharp that they could cleave a silk scarf floating to the ground, just as readily as a knight’s body.

These superlative weapons gave the Muslims a great advantage, and their blacksmiths carefully guarded the secret to their manufacture. The secret died eventually died out in the eighteenth century and no European smith was able to reproduce their method.

Now, Marianne Riebold and colleagues from the University of Dresden have uncovered the startling origins of Damascus steel using a technique unavailable to the sword-makers of old – electron microscopy.

Damascus blades were forged from small cakes of steel from India called ‘wootz’. All steel is made by allowing iron with carbon to harden the resulting metal. The problem with steel manufacture is that high carbon contents of 1-2% certainly make the material harder, but also render it brittle.

This is useless for sword steel since the blade would shatter upon impact with a shield or another sword. Wootz, with its especially high carbon content of about 1.5%, should have been useless for sword-making. Nonetheless, the resulting sabres showed a seemingly impossible combination of hardness and malleability.

Riebold’s team solved this paradox by analysing a Damascus sabre created by the famous blacksmith Assad Ullah in the seventeenth century, and graciously donated by the Berne Historical Museum in Switzerland.

They dissolved part of the weapon in hydrochloric acid and studied it under an electron microscope. Amazingly, they found that the steel contained carbon nanotubes (see left), each one just slightly larger than half a nanometre. Ten million could fit side by side on the head of a thumbtack.

Carbon nanotubes are cylinders made of hexagonally-arranged carbon atoms. They are among the strongest materials known and have great elasticity and tensile strength. In Riebold’s analysis, the nanotubes were protecting nanowires of cementite (Fe3C), a hard and brittle compound formed by the iron and carbon of the steel.

Here is the answer to the steel’s special properties – it is a composite material at a nanometre level. The malleability of the carbon nanotubes makes up for the brittle nature of the cementite formed by the high-carbon wootz cakes.

It isn’t clear how ancient blacksmiths produced these nanotubes, but the researchers believe that the key to this process lay with small traces of metals in the wootz including vanadium, chromium, manganese, cobalt and nickel. Alternating hot and cold phases during manufacture caused these impurities to segregate out into planes.

From there, they would have acted as catalysts for the formation of the carbon nanotubes, which in turn would have promoted the formation of the cementite nanowires. These structures formed along the planes set out by the impurities, explaining the characteristic wavy bands, or damask (see image at top), that patterns Damascus blades.

By gradually refining their blade-making skills, these blacksmiths of centuries past were using nanotechnology at least 400 years before it became the scientific buzzword of the twenty-first century.

The ore used to produce wootz came from Indian mines that were depleted in the eighteenth century. As the particular combination of metal impurities became unavailable, the ability to manufacture Damascus swords was lost.

Now, thanks to modern science, we may eventually be able how to replicate these superb weapons and more importantly, the unique steel they were shaped from.

Reibold, Paufler, Levin, Kochman, Patzke & Meyer. 2006. Nature 444: 286.

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Magnifection: mass-producing drugs in record time

Monoclonal antibodies are a rapidly emerging group of drugs with the potential for treating diseases from arthritis to cancer. Now, a new technique called ‘magnifection’ is set to drastically reduce the time and expense needed to make these molecules, ensuring that enough can be made to treat patients at a reasonable cost.

Imagine reading the paper to find that a new wonder drug has been created that could save your life, if only you could afford it. Alternatively, put yourself in the shoes of the authorities that must decide not to offer powerful new drugs on the NHS because they simply aren’t cost-effective enough. These situations are all too common-place and are largely a result of the extremely high costs of drug development. But recently, scientists at Icon Genetics and Bayer Bioscience have made a tremendous step toward lowering these costs for some of the most promising new treatments.

The treatments in question are called ‘monoclonal antibodies’ or ‘MAbs’, synthetic versions of the natural antibodies that our immune systems use to identify and neutralise infectious agents. MAbs are specially shaped to act like molecular gloves, sticking onto a target of choice and inactivating it by blocking interactions with other molecules.

The most famous member of this group, the breast cancer drug Herceptin, is one of a handful of currently available MAbs. But they are about to be joined by many more – over 150 MAbs are in development and the market for them is likely to exceed £10 billion.

But no matter how good these new biotechnological wunderkinds are, they will be worthless unless they reach the patients they are designed to benefit. And with the cost of treatment courses exceeding tens of thousands of pounds, that is looking unlikely. Every stage of the manufacturing process from raw materials to equipment is exorbitantly expensive and drives the inflated prices of the end product. As such, only better, cheaper and more effective production methods will enable scientists to fully realise the potential of these designer molecules.

Currently, all MAbs are grown using mammalian cells and over the past twenty years, a variety of other hosts from insects to bacteria to yeast have been considered as replacements in the search for efficiency. But all these choices have crippling flaws, with the most significant being massively lengthened development times.

Plants, one of the many possible host options, are no exception to this. While mammalian cells take at most a year to produce a gram of antibodies, plants require at least two.

Combined with complex genetics, long life-spans, the need for land and the threat of contaminating wild stocks, plants seem to be a dead end as far as antibodies go. But Anatoli Giritch and colleagues have revived their potential in spectacular fashion.

Their technique, called ‘magnifection’ uses infectious agents like bacteria and viruses to carry the instructions for making antibodies throughout the plant’s cells, hidden under multiple layers of encryption. Each antibody is a union of different molecules and the recipes for making these separate components are encoded in two different viruses – one that usually infects tobacco and another that targets potatoes. Each virus is then split into different segments and loaded into a type of bacteria called Agrobacterium.

Once Agrobacterium infects the plant, it spreads rapidly and eventually reaches about 95% of its leaf cells. The addition of a specific enzyme then acts as a trigger, causing the bacteria to begin assembling viruses. These spread locally across neighbouring cells and begin churning out antibody components, turning the plant into a monoclonal antibody factory.

The result is MAb production on a scale completely unheard of. It took this system just two to three weeks to churn out a gram of antibodies, utterly smashing the current record of 6 months. And each kilogram of host leaves were yielding 10-100 times more raw product than any other production system.

The key to magnifection’s success lies in the choice of viruses. While many virus combinations compete with each other for a host’s resources, the tobacco mosaic virus and potato virus X seem to co-exist harmoniously. Giritch et al. believe that they use different host proteins to replicate themselves and so never draw upon the same pool of resources.

The duo are now trying to tweak the magnifection protocol to achieve even better results. They will consider different virus combinations and will try to add chaperone molecules that help antibody components to combine with greater efficiency. Regardless of any further improvements, the implications for magnifection are tremendous. The technique is rapid, versatile and can be easily scaled-up. The result will be more drugs at lower prices leading, hopefully, to a better deal for patients.

Magnifection is particularly suited to situations where we might need to manufacture vast quantities of antibodies or other complex molecules in a short amount of time. A viral pandemic, or a biological terror attack, are just two examples of such emergencies.

Giritch, Marillonnet, Engler, van Eldik, Botterman, Klimyuk & Gleba. 2006. PNAS 103: 14701-14706.

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