from the Laboratory of Genomic Diversity (LGD) at the National Cancer Institute in Maryland, US, used the so-called 鈥渟hotgun technique鈥� to map Cinnamon鈥檚 genome.

This involves extracting the cat鈥檚 DNA, chopping it into overlapping fragments, sequencing each piece, and then reassembling the 2.7 billion 鈥渓etters鈥� into continuous stretches.

The process must be repeated several times to get the sequence correct, and the number of repetitions determines how complete the genome will be. For example, the dog genome was done with 7.5 repetitions making it almost 99 per cent complete. By contrast, Cinnamon鈥檚 light genome sequence was produced with just 1.9 passes, covering just 65% of the gene-coding regions.

The team filled in the blanks using extensive gene marker maps and analogous regions from the more complete dog and human genomes. , head of the LGD, and a co-author of the work, says that is the price you pay for light coverage.

Inbred advantage

The choice of cat helped, however. Cinnamon, who currently resides at the University of Missouri in Columbia, US, was chosen for the project because she is highly inbred, and so has fewer differences between her two sets of chromosomes. That makes assembling the sequence easier. The team tested many cats 鈥渁nd Cinnamon won the lottery鈥�, says O鈥橞rien.

All told, Pontius resolved 20,285 genes and thousands of different genetic variations that can be used in gene mapping, forensic analysis and studies on the history of cat evolution and domestication.

The sequence is also useful for the study of human disease: researchers have identified more than 200 hereditary diseases shared by cats and people. Cats are also susceptible to many infectious diseases similar to those that attack humans, including influenza, SARS and HIV.

鈥楲imited resource鈥�

Having the cat genome is an exciting resource, says Leslie Lyons at the University of California, Davis, US, who studies breeding, hereditary blindness, and heart and kidney disease in cats.

However, light coverage does have drawbacks, she says. 鈥淲ith a two times sequence it鈥檚 very limited. We are certainly not complaining, but it is frustrating to think that maybe only 60 to 80% of the gene you are looking for will be there.鈥�

A team at the in St. Louis, however, is planning to increase the cat genome to a six-fold draft.

Journal Reference: (vol 17, p 1675)

Rachel Batterham at University College London, UK, and her colleagues have previously shown that a hormone called peptide YY or PYY, which is released by the gut in proportion how many calories we eat, is a powerful appetite suppressant. Previous experiments show that treating normal and obese subjects with intravenous PYY decreases food intake by up to 30%.

Batterham鈥檚 team used functional magnetic resonance imaging (fMRI) to investigate how PYY affects the brain. They scanned each of eight subjects twice, once while they were on an intravenous drip of PYY, mimicking its release after a meal, and once while just receiving a saline solution. All the subjects had fasted for 14 hours prior to the scans.

Half an hour after they left the scanner, Batterham dished out an all-you-can-eat buffet of each subjects鈥� favourite meals, which included spaghetti Bolognese and macaroni cheese.

As expected, those who received PYY ate less 鈥� on average 25% fewer calories. The fMRI scans showed that PYY not only lit up the hypothalamus 鈥� the main hub for controlling metabolism, 鈥� but also increased activity in higher processing areas of the brain that are associated with reward and pleasure, notably the orbital frontal cortex (OFC). 鈥淚 absolutely wasn鈥檛 expecting it to affect the reward circuit,鈥� says Batterham.

Gastric bypass

What is more, changes in the activity of these two areas could accurately predict how much food the subjects would eat at their buffet lunch. For those on the saline drip, activity in the hypothalamus predicted how many calories they would consume. But for those subjects who received PYY, it was the pleasure centre of the brain that determined calorie intake.

Batterham hopes to repeat the study on both underweight and overweight subjects. Previous research has shown that obese individuals have lower levels of PYY and release less of the hormone after a meal compared with normal weight people. Gastric bypass surgery has also been show to boost levels of PYY. 鈥淲e still have a lot to learn about PYY,鈥� she says.

Neurologist and obesity researcher Clifford Saper at Harvard Medical School in Boston, says the study is interesting, as it is the first to explore cognitive aspects of eating behaviour with respect to an appetite hormone. What is more, he says, understanding the higher level drives behind eating behaviours is key for treating obesity.

鈥淲e humans are surrounded by all these tempting foods that taste good, and many people eat way past the point of metabolic satiety,鈥� Saper says.

Michael Schwartz at the University of Washington in Seattle, who also studies the relationship between brain activity and eating, says: 鈥淚 think it鈥檚 an impressive body of work and it does push the field forward.鈥�

Journal reference: Nature ()

The Human Brain 鈥� With one hundred billion nerve cells, the complexity is mind-boggling. Learn more in our cutting edge special report.

The comfy squish of running shoes provides feet with shock absorption and diminishes peak impact forces upon hitting a hard surface. Excessive impact is thought to contribute to running injuries such as shin splints and stress fractures.

Upscale athletic shoes often claim added protection against the bodily wear and tear of running, and indeed some studies suggest that pricier materials can more effectively reduce impact force than cheaper ones.

Other evidence, though, suggests that runners wearing fancy footwear are 123% more likely to get injured, possibly because they over-estimate the protection and run with greater impact (, vol 91, page 299).

So Richard Clinghan and his colleagues at the at the Ninewells Hospital and Medical School in Dundee, Scotland, wanted to test whether pricey shoes were more comfortable using a novel pressure-sensing insole.

Cheap and comfy

The team recruited 43 men to try out expensive ($143 鈥� $153), moderate ($123 -$133) and inexpensive ($82 鈥� $92) running shoes from three different brands. At the bottom of each shoe was a lightweight insole fitted with 99 pressure sensors to measure the distribution of pressure across the foot. Each subject also rated the shoe for comfort.

In the study, subjects did not rate the higher priced models as more comfortable than low or medium priced shoes. What鈥檚 more, the mid- and low-priced shoes actually performed slightly better on measures of overall foot pressure.

鈥淭his may suggest that less expensive running shoes not only provide as much protection from impact force as expensive running shoes, but that in actual fact they may also provide more,鈥� say the authors.

Timothy Derrick, at Iowa State University, who has tested shoes for Consumer Reports, Runners World and the US military, however, says that softness of the sole isn鈥檛 everything. 鈥淭here are many things besides cushioning that go into injury prevention,鈥� he says. 鈥淚n fact you can have too much cushioning.鈥�

Gimmicky features

Heavy runners, for example, need firmer support to keep the shoes from bottoming out. Also, well-built shoes often have so called dual-core soles with softer support on the outside of heels and harder support on the inside, which provides a stable and more comfortable landing.

Furthermore, says Derrick, impact forces themselves may not be the root cause of injury. Just as working out develops muscles, weight-bearing exercise builds healthy bones. For example, runners who routinely run on hard surfaces do not show greater levels of injuries.

That certainly suggests expensive is not necessarily better, Derrick says, who adds that most major shoe manufacturers use a very similar design and very pricey footwear is likely only useful for the injury-prone. 鈥淭here are some gimmicky shoes at the very high end where you are probably not getting any real benefit. You may be paying for a feature of a shoe that you don鈥檛 need.鈥�

But he equally advises against very cheap runners: 鈥淭hey feel great when you put them on, but they tend to deteriorate way too fast.鈥�

Journal Reference:

Studies have found that people with atopic or allergic diseases 鈥� asthma, hay fever or eczema 鈥� show a reduced risk of being diagnosed with a primary brain tumour called a glioma. These tumours are notoriously deadly: just 3% of people with the most common form live five years beyond diagnosis.

But many of these studies have been small, says Eleni Linos from the in Boston, US. To confirm the link, Linos and her colleagues conducted a pooled analysis of eight studies comprising nearly 4500 people diagnosed with either glioma or a more benign brain tumour called a meningioma.

Linos found that a people with a history of allergies were 39% less likely to be diagnosed with glioma. 鈥淚 am pretty much convinced that this is a true relationship we are seeing,鈥� she says.

鈥楾remendously encouraging鈥�

Researchers are also beginning to unravel the mechanism behind this connection, says Linos. The development of allergies is linked to alterations in the genes behind some immune-system signalling molecules called cytokines. In cell culture and animal experiments, these molecules have been found to inhibit glioma growth.

Linos found no protective relationship between allergies and the slower-growing meningiomas, however. This suggests that the protective effect on gliomas may stem from the immune activity blocking active tumour growth, rather than just detecting early abnormal cells, says co-author Tim Raine at in London, UK.

鈥淭his is just so tremendously encouraging for those working on immune-based treatments, since it implies that once a cancer is detected or established, it isn鈥檛 too late to start trying to do something about it with immunotherapy,鈥� he says.

at Ohio State University in Columbus, US, has been researching the connection between atopy and glioma for several years. Though the connection is robust, she says, Linos鈥� analysis still does not address the possibility that the tumour itself is behind the drop in allergies.

Gliomas are known to be potent suppressors of the immune system, she notes: 鈥淚 am still not completely convinced that it鈥檚 not the tumour suppressing the allergy.鈥�

Journal Reference:

Cancer 鈥� Learn more about one of the world鈥檚 biggest killers in our comprehensive special report.

鈥淵ou can be treated immediately for the disorder when you are in maximum crisis,鈥� says the lead author at the University of Virginia, Charlottesville, US.

Johnson and colleagues followed the progress of 317 individuals with alcohol dependence for 14 weeks. Half received treatment with the drug topiramate, an anti-convulsant sold under the brand name Topamax, while the other half received a placebo.

At the start of the study, participants were averaging about 11 drinks per day, and drinking heavily on more than 80% of their days. They totally abstained on approximately three days a month.

By the end of the study, those receiving the drug reported drinking heavily on just 20% of days. They also averaged only 3.5 drinks per day, and managed to stay completely sober more than half the time.

Pleasure blocking

The control group also improved, but significantly less. They drank heavily on more than 40% of days, consumed six drinks per day, and abstained from drinking about a third of the time.

Topiramate works by blocking the release of the neurotransmitter dopamine, which reinforces the pleasurable feelings that alcoholics get when they drink.

In an accompanying editorial, Mark Willenbring at the US says the primary problem now is how to improve patient access to treatments like topiramate, since alcohol abuse remains a woefully under-treated disorder.

鈥淥ne potential solution is for primary care physicians and psychiatrists to begin systematically identifying and treating alcohol dependence in their patients,鈥� he says.

Topiramate, which is not currently approved by the FDA for alcohol abuse, is already being used 鈥渙ff label鈥� for this disorder, according to Johnson. 鈥淢y hope is that topiramate continues to be validated and tested by other doctors, and if they want to [prescribe it off-label], they should.鈥�

Journal Reference: (vol 298, p 1634)

Drugs and Alcohol 鈥� Learn more in our comprehensive special report.

Cats were domesticated in the Near East from local wildcats, according to a new kitty family tree based on DNA evidence from nearly 1000 animals.

The finding supports the idea that cats were tamed throughout the 鈥淔ertile Crescent鈥� as humans settled down and became agriculturalists. Grain stores would have attracted rodent pests, which in turn may have lured wildcats into a closer relationship with people, which eventually led to the modern house cat.

鈥淎 lot of domestication models involve a single domestication event and then dispersion. But what we now see in cats, is multiple events where people tinkered with breeding or where a domestic partnership arose,鈥� says Melinda Zeder, director of archaeobiology at the National Museum of Natural History in Washington DC, US.

Piecing together the history of the domestic cat has been tricky because the skeletons of wildcats and house cats are virtually indistinguishable. All that separates them are coat colour variations, a slightly smaller size and, of course, a more friendly demeanour.

DNA analysis

Cats were neither hunting nor herding helpers, like dogs, or food sources, like cattle, meaning that archaeological records of cat and human relationships are less abundant.

Carlos Driscoll at the National Cancer Institute in Frederick, Maryland, US, and colleagues sampled DNA from 979 domestic cats and wildcats from across Europe and Asia. By analysing the variations in DNA sequence at different 鈥渕arker鈥� spots in the genomes, they were able to tell which felines were the most closely related.

The team found that wildcats and domestic cats separate out into five groups, or clades, of the wildcat Felis silvestris, which correspond to different subspecies: the European wildcat, the Southern African wildcat, the Central Asian wildcat, Chinese desert cat and Near Eastern wildcat.

Near East origin

All of the domestic cats 鈥� from the fancy breeds to feral tabbies 鈥� fell within the Near Eastern wildcat group.

Furthermore, lap cats descended from five distinct mitochondrial DNA lineages. 鈥淭hese new molecular data support previous genetic and archaeological findings, which suggested that domestic cats originated from the domestication of North African or Near Eastern wildcat populations,鈥� says wildlife geneticist Ettore Randi at Italy鈥檚 National Institute for Wild Animals (INSF).

Driscoll鈥檚 tree also suggests that the Near Eastern clade, domestic cats included, split from the other wildcats around 131,000 years ago.

The earliest firm evidence of such cats comes from Egyptian art dating to the 20th century BC. But in 2004, French archaeologists uncovered a 9500 year-old burial site in what had been newly agricultural Cyprus containing both human and cat remains. This sparked the question of whether cats and humans began to co-habitat much earlier.

Journal Reference: (DOI: 10.1126/science.1139518)