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July 12, 2013 6:26 pm
Archaeological studies in Iran show that the transition from foraging to farming took place simultaneously right across the Fertile Crescent from the Mediterranean to the Zagros Mountains, between 12,000 and 10,000 years ago. Agriculture did not start in a single core area within the “cradle of civilisation”, as some have argued.
The new evidence comes from a German study at the Neolithic site of Chogha Golan in the Zagros foothills, published in Science. People there were cultivating wild cereals, including barley and wheat, and progenitors of other modern crops, including lentils and peas, at the same time as inhabitants of settlements farther west in Mesopotamia and the Levant.
Political pressures have made it relatively difficult until recently to excavate sites in Iran. But the work by archaeologists from the University of Tübingen at Chogha Golan since 2009 shows that its inhabitants were not only growing wild plants but also beginning to domesticate emmer wheat during their period of occupation from 12,000 to 9,800 years ago.
Chogha Golan, about three hectares in size, preserves a rich archaeological sequence across the whole of this period. The deposits contain clay figurines representing people and animals, worked bone artefacts and many stone mortars and grinding tools. Animal remains include goats, boar, gazelles, horses, cattle, hares, birds, fish and shellfish. A substantial population must have lived there over more than two millennia of relative economic and social stability.
“Plentiful findings of chaff remains of the cereals indicate that people processed their harvest within the sites they were living in,” says Simone Riehl, the study leader. “Mortars and grinding stones may have been used for turning the grain into some kind of bulgur or flour, which may have been further processed either by cooking or roasting.” Chemical analysis of the stone tools shows that they were used for multiple purposes, not just grinding grain.
Crocodiles and alligators have multisense organs all over their skin, which have no equivalent in other animals. They are sensitive to touch, heat, cold and chemicals, according to new research.
The findings at Chogha Golan are consistent with the local development of agriculture, but the researchers say that farming practices may have been exchanged across the Fertile Crescent.
“For some time, the emergence of agriculture in Iran was considered as part of a cultural transfer from the west,” Riehl says. “This opinion was, however, mostly based on the lack of information from Iranian sites.
“We meanwhile assume that key areas for emerging domestication existed over the whole Fertile Crescent, and that there were several locations where domesticated species evolved as a result of cultivation by local human groups.”
Better DNA through chemistry
A small UK biotechnology company has developed a new chemical process for mass-producing DNA, which could transform fields from vaccines to synthetic biology.
The conventional way of making many copies of a specific stretch of DNA is biological. A “plasmid” – a round piece of DNA containing the desired sequence – is inserted into bacteria which multiply themselves and the plasmid in a fermenter. Then the DNA has to be isolated and purified.
In contrast Touchlight Genetics, based in Leatherhead, Surrey, achieves the same multiplication effect without bacteria, in a process that uses two enzymes but no living cells. It produces stable sequences of DNA closed by telomeres similar to the caps at the end of human chromosomes.
“Compared to the expensive and complex process of plasmid production, our technology is simple, flexible and can be automated without a large fermentation infrastructure,” says Clive Dix, a biotech veteran who chairs Touchlight.
The first application for the technology will be to make DNA vaccines. These contain the genetic instructions to make a protein “antigen” that stimulates the immune system to recognise and attack a particular pathogen.
In principle, injecting DNA directly into the patient offers advantages over a traditional vaccine containing antigen. DNA vaccines can be designed and produced more quickly, they induce a wide-ranging immune response, and their high stability removes the need for a cold chain.
Four DNA vaccines made with plasmid technology have been approved for veterinary use and more than 100 are in clinical trials for human use, though none has yet received a commercial licence.
Dix sees many other applications for Touchlight technology including producing DNA as an identifying security tag for valuable products and in synthetic biology.
Technology points the finger
Fingerprints remain the cornerstone of forensic investigation, with 700,000 objects fingerprinted every year in Britain. The microscopic details of their ridges and troughs are unique to every individual on the planet.
Yet the success rate in visualising “latent fingerprints” – ones that are not clearly visible and therefore less likely to be wiped by criminals – remains poor. Just 10 per cent of prints taken from crime scenes are high enough in quality to provide forensic identification in court.
The conventional way of showing up latent fingerprints is to apply a powder or chemical reagent, which sticks to the residue of sweat and oils in the print and provides a contrast to the underlying surface. But researchers at Leicester University working with two neutron sources – Isis in the UK and Institut Laue-Langevin in France – have come up with what appears in lab tests to be a superior method for revealing prints on metal surfaces.
They exploit the fingerprint’s electrically insulating properties. Its organic chemicals act as a mask or stencil, blocking the current that is used to deposit an electro-active film on the surrounding metal. The effect is to create a negative image of the print, which is then enhanced by adding fluorescent molecules to the film.
“By using the insulating properties of the fingerprints to define their unique patterns … we can dramatically improve the accuracy of crime scene fingerprint forensics,” says Robert Hillman, project leader. “From the images we have produced so far, we are achieving identification with high confidence [and] also opening up fingerprint analysis to a far wider set of samples, particularly those eroded by ageing or aggressive environments.”
Gold leaf: the milky way
Researchers at ETH Zurich in Switzerland have made an ultra-thin “gold paper” – a hybrid material of gold and milk proteins – which looks just like traditional gold leaf and has applications in a range of different fields, from gastronomy to jewellery.
The team produced its new gold paper from a chemical process involving milk proteins and gold salts. It has layers of microscopic flat crystals of gold mixed with the protein fibres, which are structured rather like the cellulose fibres of conventional paper.
Production of the hybrid material requires only one-third the amount of gold to give the same appearance as gold leaf made in the traditional way by hammering the metal into a sheet. “When you consider how much pure gold costs, this new material makes a massive difference,” says Raffaele Mezzenga, the project leader.
He sees the first application as gastronomy, where gold leaf has long been used to decorate desserts and drinks, particularly in the Middle East and Asia. Clock and watch makers could use “lactogold” to apply golden numbers to the faces of their timepieces.
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