the-BA : Science News Digest

Mouse on cheese (image copyright: istockphoto.com)

In the science news this week: a colourful ‘brainbow’, a rodent Lance Armstrong that loves running and a bulletproof yarn that repels bullets. Plus, Ming the 405 year old mollusc...

Scientists have used new staining techniques to create a ‘brainbow’ that reveals the intricate connections of brain cells at a level not seen before. The Times compared the result to an abstract work of art but, in addition to being beautiful, the method offers new insight into the maturation and interactions of nerve cells, helping neuroscientists to map out the complex wiring diagram of the nervous system.

In the work, published in Nature, researchers from Harvard University genetically modified mice so that individual neurons are labelled with approximately 90 different colours. The animals were engineered to carry genes that express four fluorescent proteins – green, red, yellow and orange. A recombination method was then used to shuffle the genes, so that individual cells would produce different, random combinations of the proteins.

‘In the same way that a television monitor mixes red, green and blue to depict a wide array of colours, the combination of three or more fluorescent proteins in neurons can generate many different hues,’ said Professor Jeff Lichtman, one of the team.
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Another genetically engineered mouse described this week has been termed ‘mighty mouse’ and compared to Lance Armstrong, thanks to its ability to far out-perform its unmodified relatives on the treadmill.

500 mice which produce excessive amounts of the phosphoenolpyruvate carboxykinase (PEPCK-C) enzyme in their muscle now exist in a lab colony, and each is easily identifiable by its running behaviour. They are capable of moving at three quarters of a mile per hour for three miles at a time and, while they eat 60 per cent more food than normal mice, they stay fitter, trimmer and live longer. They also appear to be able to reproduce at a much older age than their wild peers.

Commenting on speculation that genetic engineering could one day be abused by athletes, Professor Richard Hanson, senior author of the paper published in the Journal of Biological Chemistry, said: ‘I do not think that this type of experimental approach has a parallel for altering human performance. It is currently not possible to over-express a gene in the muscle of a human and (thank goodness) it would not be allowed.’

He added: ‘This type of approach to human biology was not our intention in designing these mice. We were simply trying to better understand the metabolic role of PEPCK-C in skeletal muscle.’

A video showing the behaviour of the mice is available on the Telegraph’s website.
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The Telegraph also reported that scientists have identified a molecular signal that gives newts the amazing ability to regenerate damaged or severed limbs.

A key part of the limb regrowth process is the formation of a ‘blastema’. This mound of cells forms at the tip of the injury and has the potential to grow into a variety of cells. The cells rapidly multiply and develop into specific cell types which go on to form a new limb. If a blastema is transplanted to another area of the body, it is possible to grow a limb there.

In the new work, published in the journal Science, scientists from University College London discovered that growth of the blastema is triggered by a protein called nAG, which is made by cells at the end of the limb stump.
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BBC News revealed that the strain of HIV that predominates in the US and Europe came to America via Haiti, and arrived much earlier than previously thought, sometime around 1969. It then spread further and is now the major form in the US, Europe, large parts of South America, Australia and Japan.

Scientists reached their conclusion after analysing the genetic sequence of the virus from different patients around the world, using the data to construct a family tree for the virus. Their study included the archived blood from five early AIDS patients, who were all Haitian immigrants to the US.

Michael Worobey of the University of Arizona in Tucson believes understanding the origins of this and other strains of HIV will help scientists to predict how the virus may mutate in the future.
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In other medical news, researchers have discovered that type O blood protects against the most deadly form of malaria. Their work suggests that group O blood cells are less likely to form ‘rosettes’ of sticky cells when infected by malaria parasites, and therefore don’t clog up tiny blood vessels which can deprive the brain of oxygen.

Alongside colleagues from Mali, Kenya and the US, Dr Alex Rowe from Edinburgh University found that African children with this blood type were two-thirds less likely to fall into an unrousable coma or develop life-threatening anaemia.

Dr Rowe told the Telegraph: ‘If we can develop a drug or a vaccine to reduce rosetting and mimic the effect of being blood group O, we may be able to reduce the number of children dying from severe malaria in sub-Saharan Africa.’
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Steer clear of processed meats such as bacon and ham, was the stark warning from a report by the World Cancer Research Fund (WRCF). The in-depth analysis of 7,000 cancer studies conducted worldwide since the 1960s has revealed that they are such a risk factor for bowel cancer they should be avoided completely if at all possible.

The study also found that there is ‘convincing’ evidence that excess body fat is a causal factor in six different types of cancer, reported the Independent, including bowel, breast and pancreatic.
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After such news, the following work by British scientists is even more welcome. They have demonstrated, for the first time, a new light-activated cancer therapy that destroys tumours without damaging healthy tissue.

The Guardian reports that the therapy has already been used to cure ovarian tumours in mice and holds promise against a wide variety of human cancers. The first clinical trials are scheduled to begin next year, and will probably tackle skin cancer. Safety trials could take a further ten years.

Whereas chemotherapy and radiotherapy can have nasty side-effects because they kill healthy cells as well as cancerous ones, the new drug offers a more targeted approach.

The therapy involves antibodies – proteins that help fight infection and disease – that are coated in a light-sensitive shell. The coating ‘cloaks’ the antibodies, stopping a huge immune reaction from taking place when they are injected. By aiming a targeted beam of UV light at the tumour, only the antibodies in that specific area are activated. These attract killer T cells, part of the body’s natural immune system, which then destroy the tumour.
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Domestic cats have joined the list of animals that have had their genome sequenced, reported BBC News. An Abyssinian cat called Cinnamon provided the DNA.

So far, only a rough version of the feline genome has been obtained but it has already helped scientists identify the gene mutation responsible for retinitis pigmentosa, a degenerative eye disease in cats. Since humans and cats have many illnesses in common, including this hereditary blindness, understanding the feline genome could also help shed light on human diseases.

The sequence will also provide information about the animal’s evolution and more detailed comparisons with the genomes of other creatures will be possible when a more complete version is finished next year.
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BBC News reported that another DNA study has revealed that Colugos, gliding mammals from south-east Asia, are our closest relatives after apes, monkeys and lemurs. The work shows they are more closely related to primates than tree shrews, contradicting what many experts thought.

The colloquially named ‘flying lemur’, that neither flies nor is a true lemur, is on the list of 26 mammals chosen by the National Human Genome Research Institute in the US to have its genome sequenced ‘roughly’ (meaning incompletely), such as Cinnamon the cat has just had. The team who conducted this latest research are calling for full sequencing.
They say their research will help ‘better interpret early primate evolution and those changes at the DNA level and in skeletal appearance that led to modern primates and ultimately to the human lineage itself’.
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A carbon nanotube yarn could be used to make bulletproof materials more effective at protecting wearers than Kevlar, reports the Telegraph.

Conventional bulletproof clothing can still leave users with severe bruising or damage to organs because the fibres that stop the bullet penetrating the clothing spread the bullet’s force. In contrast, a new nanomaterial is able to deflect bullets rather than absorbing their force.

Engineers from the University of Sydney Centre for Advanced Materials Technology tested the force-repelling properties of carbon nanotubes and concluded that ‘six layers of woven nanotube yarn - about 600 millionths of a metre thick - may protect the wearer from a revolver bullet, so that it bounces off.’
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A kilogram isn’t quite what it used to be, apparently. Currently, the kilogram is defined in terms of a cylindrical lump of platinum and iridium held in a high-security underground safe on the outskirts of Paris.

‘That piece of metal, by definition, is a kilogram, but we know that over that period there's a lot of evidence it has been changing its mass,’ said Seton Bennett, Deputy Director of the National Physical Laboratory. ‘It may have changed by 50 parts in a billion. Now that's not a huge amount in terms of practical weighing, but it is becoming significant and we need to do something about it.’

Rather than define a standard unit of measurement in terms of a physical thing, it would be much better to use a fundamental physical property, writes James Randerson in the Guardian. British researchers have brought that possibility one step closer thanks to an incredibly accurate measurement of one such physical property, called the Planck constant. The value differs from a previous measurement by American scientists, but by a mere 308 parts per billion. If the measurements can be brought even closer together it should be possible to agree a value against which to define the kilogram.
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And finally...

Researchers have dredged up a clam from the coast of Iceland that is thought to have been between 405 and 410 years old – making it the oldest living animal ever discovered.

Professor Chris Richardson, from Bangor University in Wales, told BBC News: ‘What's intriguing the Bangor group is how these animals have actually managed, in effect, to escape senescence [growing old]. One of the reasons we think is that the animals have got some difference in cell turnover rates that we would associate with much shorter-lived animals.’

The age of the mollusc was calculated by counting the rings on its shell. It has been nicknamed Ming, after the Chinese dynasty in power when it was born.

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