Can a GM mosquito stop dengue fever?

Disease prevention

GM mosquitoes bred to fight dengue fever

The first field trial of genetically modified insects to fight human disease has given encouraging results. The release of three million sterile GM mosquitoes on the Caribbean island of Grand Cayman will be followed by about five similar trials around the world over the next year.

The initial target is Aedes aegypti, the mosquito that spreads dengue fever. The disease, which originated in Africa, is estimated to infect 50 million people every year, and kill 25,000. There are no vaccines to prevent it, or drugs to treat it.

The technology comes from Oxitec, a spin-out company from Oxford University, which inserts a “dominant lethal gene” into insects. This enables males to produce viable sperm and fertilise females, but the resulting larvae always die before hatching. The idea is to release vast numbers of sterile male insects – at least 10 times more than the wild population. They swamp the native males and mate with all available females, which fail to produce viable offspring.

A similar “sterile insect” approach, achieved by radiation, has had great success in eradicating some agricultural pests in North America, but mosquitoes cannot be sterilised through irradiation.

Oxitec had hoped to launch its first dengue fever field trial in Malaysia, but that plan has been held up by regulatory problems and criticism from some anti-GM campaigners. Oxitec hopes the Malaysian trial will start later this month. The delay enabled the Cayman Islands, where Aedes aegypti mosquitoes arrived in 2002, to get in first. “We had no opposition,” says Angela Harris of the Cayman Islands Mosquito Research and Control Unit. “The people living in the trial area were very pleased.”

Three million sterile male mosquitoes were released on the 16-hectare trial site between June and last month. Early results confirm that they swamped the wild males and cut the number of mosquitoes by 80 per cent, compared with the untreated site next door. Luke Alphey, Oxitec chief scientist, says the remaining 20 per cent flew in from untreated areas and would not be present if the release covered a wide area.

Oxitec insists that its GM mosquitoes are environmentally benign and represent the only hope of rolling back the global advance of dengue-infected mosquitoes. The male mosquitoes do not bite, and the density required is not great: a large-scale urban programme would release around 20 mosquitoes per human inhabitant per week. In addition, Aedes aegypti are an alien species spread by human activity into the areas of Asia and the Americas where they are targeted for GM attack, so their eradication would not disrupt local ecosystems.

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DNA research

Swedes halfway to mapping human proteins

Since the completion in 2003 of the Human Genome Project, scientists have sought to make sense of the three billion chemical “letters” of our DNA. That means looking at the products of the genetic code – the proteins that do most of the work in our bodies, known collectively as the proteome.

Sweden’s €100m Human Protein Atlas, funded by the Wallenberg Foundation, aims to map proteins within the body at three different levels: showing where the proteins are inside cells, which types of cell contain what proteins, and the location of proteins in specific tissues and organs.

The proteome is more complex than the genome, because the 20,000 human genes generate a much larger number of proteins. Some genes can be “read” in different ways, producing alternative proteins, and many proteins are altered biochemically in the body after their initial production.

To make the 10-year project manageable, the Human Protein Atlas is proceeding on the simplified assumption that one gene makes one protein, giving it a target of mapping 20,000 proteins by the proposed completion date of 2015. So far it has reached 10,000.

The Swedish scientists, based at Uppsala University and Stockholm’s Royal Institute of Technology, are using an antibody approach. For each of their chosen proteins, they make an antibody; this targets the molecule, showing where it is present and absent in cells and around the body.

Mathias Uhlén, the project founder, says the 20,000 proteins will be a foundation for subsequent mapping of their variants. “Proteins govern every way that the body grows and develops,” he says. “If we can properly understand the behaviour of each of these 20,000 proteins we will unlock the code to understanding how and why diseases develop, paving the way for more successful treatments and better diagnostic tools.”

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Agriculture

Could chemical crops halve US oil imports?

If biomass crops are to make a big contribution to future fuel supplies, without having an adverse impact on food production, researchers will have to discover how to extract far more energy from the stalks and woody parts of plants than is possible today. That means converting hard biological materials – cellulose and lignin – into useful organic molecules that can replace transport fuels and petrochemicals.

Most research today focuses on biological processes – micro-organisms and enzymes breaking down cellulose into sugars, which in turn are converted into biofuels. But this is relatively inefficient and does not make use of lignin, which is even more recalcitrant than cellulose and accounts for up to 30 per cent of biomass sources.

Scientists at Purdue University in Indiana are working on an alternative approach, using genetic engineering. Their research, funded by the US Department of Energy, aims to produce crops that incorporate a chemical catalyst directly into the biomass as they grow. After harvesting, the catalyst would work in a refinery to convert the cellulose and lignin into useful fuel and other organic molecules.

Maureen McCann, the project leader, says the work is in its early stages and could not lead to a commercial process in fewer than seven to 10 years. But the potential rewards are huge.

“We could have a good shot at displacing half of our oil imports, though this depends on carrying out a large amount of research,” she says.

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Econophysics

Been Googled? Check your share price

The new research field of econophysics – at the interface between economics and physics – has shown a clear link between “financial markets and the ‘swarm intelligence’ of the internet”, according to a study by German and American scientists.

Researchers at Johannes Gutenberg University in Mainz and Boston University in Massachusetts analysed the number of searches on Google for all companies whose shares are included in the S&P 500 index. They used search data for the six years from 2004 to 2010, which Google provides for scientific studies. The results show a strong correlation between weekly share transaction volumes of the S&P 500 companies and the weekly volumes of Google searches for their corporate names. More searches mean more share trading.

“One can conclude that search volume reflects the present attractiveness of trading a stock,” the researchers report in the journal Philosophical Transactions of the Royal Society A. “The commonly accepted reasons for financial market movements – news and volume – are clearly linked together, because news should be the most likely reason for searching company names.”

Sadly, however, the study showed no significant correlation between stock price variations and search volume. As Google activity about a company increased, shares were just as likely to fall as to rise.

The authors plan next to carry out deeper analysis of the relation between search data and market behaviour, in the hope of understanding better the factors that trigger financial crises.