The cells are found exclusively in the cerebral cortex – the part of the brain responsible for functions such as language, thought, sensation and spatial reasoning – and named for their resemblance to old-fashioned candlesticks.

at the University of Szeged, Hungary, and colleagues have for the first time demonstrated just how powerful chandelier cells are, by showing that a single cell can trigger a whole series of neuronal signals in human brain tissue. As this has not been seen in other mammals, it may explain why we humans are so much brighter.

Tamás’s team investigated how chandelier cells make connections with other nerve cells using brain tissue removed during surgery that would otherwise have been “wasted”.

“We used tissue from patients having surgery for deep brain tumours,” he says. “On the way to these deep brain tumours surgeons have to remove some healthy cortical tissue above the troubled area. We used this little piece of healthy tissue which would have otherwise been discarded.”

The power of one

The researchers recorded the electrical signals produced as pairs of connected neurons fired, allowing them to determine how individual neurons affect others. They found that a single chandelier cell can trigger a cascade of firing in several pyramidal cells, the “work horse” cells of the brain that allow communication between brain areas.

Hundreds of nerve cells usually have to send a signal to the pyramidal cell in order to kick it into action. The chandelier cell however makes a unique contact with the pyramidal cell so that a signal from just one chandelier cell produces the same effect.

“The chandelier cells are extremely potent at stimulating pyramidal cells. They are probably the most potent cell type in the brain compared to all other non-pyramidal cell types,” says of University College London.

“[A chandelier cell] has a much more profound impact on the ability of the pyramidal cell to fire a signal. It has a very loud voice so if it has something to say, everything will hear it,” he says.

TamĂĄs says chandelier cells help the cortex pass on longer sequences of information like a series of tumbling dominoes. Chandeliers are also found in other mammals such as rats, in which they are involved in touch perception. But they are much more abundant in humans, and the new work shows that the synaptic pathways they form are far stronger than in other mammals.

Journal reference:

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

Ecological studies into predator-prey relations have traditionally shown that wolves feed on hoofed animals like deer, elk and moose, particularly during the spring and summer. However, ecologists have recently noticed that the fanged animals can capture and eat salmon in the autumn when the fish swim upriver.

The suggestion has been that wolves fall back on salmon as an alternative food source when deer are scarce. But and colleagues at University of Victoria and Raincoast Conservation Foundation, British Columbia, Canada, have shown that wolves actually prefer salmon, whether or not deer are on the menu.

Darimont and colleagues spent four years studying the feeding habits of eight packs of wolves in the Great Bear Rainforest region of British Columbia.

Seasonal snack

Spawning salmon are unavailable for most of the year. They leave rivers at the start of spring the size of a human finger and spend up to five years growing in the ocean. When they return to their native streams in the autumn, often the size of a five-year-old child, they offer a huge pulse of nutrients to predators that can harvest the creeks.

Salmon is rich in fat compared to deer, containing four times the amount of caloric energy per bite. Combined with the fact that they are predictable, spatially constrained in creeks and don’t fight back like deer do, salmon is an ideal food resource.

Darimont and his team used genetic tests to analyse over 2000 droppings and 60 hair samples to determine their wolves’ dietary habits.

“Hair is metabolically inert, so it records what that wolf was eating during that time of hair growth,” explains Darimont.

The results show a seasonal shift in diet from deer in spring and summer to salmon in the autumn, even when deer is readily available – suggesting the availability of salmon is driving the change in feeding.

Easing exploitation

This means, says Darimont, if commercial salmon fishing continues at the rate it is now, the implications for wolves and other species could be disastrous.

Although wolves have deer as a fallback, other species like mink and grizzly bears rely heavily on salmon. The ability of female grizzlies to bear young is completely dependent on salmon availability, as is breeding and lactation in mink.

For these reasons, human exploitation of salmon must be scaled down, says Darimont. He supports the Canadian government’s , which aims to put the needs of the ecosystem ahead of those of the fishing industry when managing salmon stocks.

Journal reference: , DOI: 10.1186/1472-6785-8-14

At the heart of almost all human cancers is a rogue enzyme, telomerase. Now the structure of a key catalytic component of the enzyme has been discovered, paving the way to more effective anti-cancer and, perhaps, anti-ageing drugs.

Telomerase is responsible for adding unique repetitive sequences of DNA, called telomeres, at one end of chromosomes. These telomere caps ensure the chromosomes don’t fall apart, but because telomerase is dormant in most adult cells each time a cell divides, its telomere loses a chunk of DNA. Eventually, when cells can no longer divide, they die – this protects against cancer.

When telomerase is more active than it should be, telomeres don’t get shorter. Instead, cells continue dividing beyond their normal limits, and become cancerous.

This has made telomerase a prime target for anti-cancer and anti-ageing therapies, but a lack of information on the structure of its catalytic subunit, TERT, has hindered progress.

Beetle bonanza

and his team from The Wistar Institute, Philadelphia, finally cracked the structure when they discovered that a gene in an insect – the flour beetle – could be harnessed to produce the enzyme in massive quantities.

This enabled the team to analyse TERT using .

“Structural studies of telomerase have been extremely difficult due to the size and complexity of the enzyme, which in turn made it difficult to isolate the protein component of telomerase in sufficient, stable quantities for the proposed studies,” says Skordalakes.

The structural analysis reveals that TERT (telomerase reverse transcriptase protein) consists of three domains, and forms a ring-like doughnut structure that creates a central hole. When the telomere is being built, this hole allows a nucleic acid template molecule about eight nucleotide bases long to fit inside.

Anti-ageing drug?

Previously scientists had thought that the structure of the enzyme is similar to HIV transcriptase and developed anti-telomerase drugs accordingly. The structural analysis confirms there is a similarity, but it also reveals that one of the domains in the TERT protein – called the carboxy-terminal extension or CTE – has a unique type of protein fold, never been seen before.

This feature could help develop anti-telomerase drugs that specifically target the fold.

“Now that they know what the structure of the catalytic subunit is, they can design drugs that can bind to the protein subunit and either inhibit its activity for anti-cancer treatment, or promote its activity as anti-ageing therapy,” says , from The School of Pharmacy, University of London, UK.

Neidle says developing drugs to target the enzyme could be used in combination with existing anti-telomerase anti-cancer therapies currently in clinical trials, such as a class of telomerase vaccines.

of the Methuselah Foundation says: “If we had a really cast-iron therapy against all cancers, it might well be a good idea to stimulate telomerase, with a drug, for example, that might have widespread anti-ageing effects.”

Journal reference: (DOI:10/1038/nature07283)

Cancer – Learn more about one of the world’s biggest killers in our comprehensive special report.

That, in a nutshell, is the message from a (pdf format), presented today by the (CSDH), an advisory body to the World Health Organisation.

The CSDH found that quality of life, health and life expectancy varied dramatically, depending on socioeconomic conditions.

For example, a boy living in one suburb of Glasgow, UK, is expected to live 28 years less than a boy born in another just a few miles away. A baby born to an uneducated Bolivian mother is 25 times more likely to die than a baby born to a Bolivian mother with secondary level education.

So what can be done to reduce health inequities around the world independently of science and medicine? We review what the commission found and recommended to “help people fulfil their biological potential”.

The wealthier the country, the healthier the population, right?

Not necessarily. Even if a country becomes wealthier, the population’s health may not improve unless the income is used and distributed wisely to promote equality in the various “social determinants of health” – education, employment, basic amenities and gender equality.

Some countries and regions with low per-capita wealth, such as China, Cuba and the Indian state of Kerala have improved health regardless of a lack of money.

How does the commission suggest we achieve global health equity?

The key is to look beyond the temporary solutions provided by health-care and medicine. It is social injustice that leads to deeper health inequalities, the commission finds.

Commission chair Michael Marmot has three key recommendations:

1. Provide care and support to all members of society, from newborn babies to the elderly, from education to employment to retirement. Invest in schooling, safe working environments, affordable housing, health-care and public transport.

2. Manage access to fatty foods, alcohol and tobacco, develop a well-financed public sector to fund projects, and promote gender equality and political empowerment.

3. Measure, research and understand problems, and train individuals to monitor and assess the impact of actions taken to improve health equity.

Will there be policy changes as a result of the report?

The commission was set up by the WHO to provide independent advice regarding health inequity. It is up to individual governments to decide what to do with the information – such as the finding that the more readily available alcohol and junk food are, the more likely people will consume them to the detriment of their health.

But the commission says every government policy and initiative should be assessed for its impact on health.

Did the commission put forward any radical ideas?

An international tax on foreign exchange dealings was one possibility considered by the commission. Revenues would be fed back into a global development fund.

In the meantime, Marmot hopes to spread the message that global health inequity should and can be overcome by implementing some key changes in the social, economic and political order of countries. He hopes that engaging in discussions with individual governments will help make the report relevant to the specific needs of a country.

No matter how hard men try, they may not be able to hide their aggression. A study in male ice-hockey players suggests that to gauge a man’s aggression levels, you just have to look at the proportions of his face.

and Justin Carre from Brock University in Ontario, Canada, found that the larger the width-to-height ratio of a player’s face, the more aggressive they were.

They measured aggression by the number of penalty points each player accrued for potentially harmful behaviour, such as elbowing and fighting.

In general, men’s faces tend to have a larger width-to-height ratio than women’s. This physical characteristic has been linked to higher levels of testosterone, which in turn is linked to aggressive behaviour.

Most people would not want to pick a fight with a big, brawny man, but because facial ratio is not linked to body size, it may have been favoured by evolution to warn others of an aggressive personality they would not want to tangle with.

Real world results

Although the team first found the result in a study of students playing computer games, McCormick says they were “astounded to see that the measure could predict aggressive behaviour in a ‘real world’ setting”.

on facial metrics have suggested that women can tell whether a man wants children just by looking at their photograph. Now McCormick’s study raises the question of whether people can spot these subtle facial differences and use it to guide everyday behaviour.

“If someone was given the choice of one of two opponents to compete against who differed on the basis of the facial metric, would the facial metric predict the less aggressive opponent?” asks McCormick.

She believes that people’s faces may be influencing who we chose to socialise with on a daily basis.

Journal reference: (DOI:10.1098/rspb.2008.0873)