LEN

A JO

HAN

SSO

N/W

OR

DIC

/GET

TY

SIM

ON

/CO

RB

IS JA

RR

AT

THE planet’s climate was on the brink of entering a permanent ice age before humans intervened .

The ice caps at Earth’s poles formed only in the past 30 million years , as levels of carbon dioxide in the atmosphere fell. Then around 2.5 million years ago, as the overall cooling trend continued, something strange happened: the climate began see-sawing ever more wildly between conditions like today and ice ages every 20,000 to 50,000 years (New Scientist, 6 September, p 32 ).

According to a simple climate model developed by Thomas Crowley at the University of Edinburgh, UK, these oscillations were a sign that the climate was set to flip to a new stable state: a permanent ice age lasting tens of millions of years or more. This flip could have occurred in about 100,000 years from now, or possibly earlier. “It’s not proven, but it’s more than just an interesting idea,” he says ( Nature, vol 456, p 228 ).

However, by pumping so much CO2 into the atmosphere we have delayed this transition indefinitely. “We are probably very comfortably away from it happening now,” says Crowley.

Global warming saved the day

INJECTIONS of reovirus, a harmless virus that infects most people at some point but rarely causes symptoms, appears to boost the action of cancer drugs.

At a meeting last week of the International Society for Biological Therapy of Cancer in San Diego, California, Oncolytics Biotech of Calgary in Alberta, Canada, reported positive results from two trials of its drug Reolysin, which contains reovirus. In one, at the Royal Marsden Hospital in London, nine patients were given Reolysin plus the standard anti-cancer drugs

paclitaxel and carboplatin. Cancers stopped growing in four people and shrank in another four, staying that way for at least seven months after treatment . The patients had failed to respond to other drugs.

The second trial took place at the Royal Surrey County Hospital in Guildford, UK. Eleven patients with a variety of cancers received Reolysin plus the drug docetaxel. Nine had positive responses.

Because Reolysin was used with other drugs in these trials, some researchers caution that the results don’t show that the virus

definitely helps. In a third trial , though, cancers were stabilised in six out of 29 people with an untreatable type of lung cancer who were given only Reolysin. However, larger trials are needed.

Reovirus works because it infects cells that have a defect in a gene called Ras. This defect causes cells to multiply uncontrollably, making them cancerous, but it also prevents cells fighting viral infection, so the reovirus can kill them . About 60 per cent of primary tumours and 90 per cent of secondary ones have the Ras defect.

Harmless virus harnessed to attack tumours

THE way birds can sing the same song at the same speed day after day has long been a mystery. Now it has emerged that an area in the brains of zebra finches acts as a kind of music box, controlling the speed at which the birds sing. A similar mechanism may also help to control the speed of human speech.

Michale Fee and Michael Long at the Massachusetts Institute of Technology investigated by implanting small coolers at various sites in the finches’ brains. The devices cooled that part of the birds’ brains by up to 6.5 °C.

When the cooler was implanted into an area called the HVC, which is involved in both learning and producing birdsong , they found that the birds sang the same song, but more slowly (Nature, DOI: 10.1038/nature07448). The equivalent area in human brains controls movement.

The HVC contains several groups of neurons that are activated at different points during a song. Fee and Long’s finding suggests that the timing of these bursts of activity is regulated by the HVC.

Fee likens the action of the HVC to that of the rotating drum in a wind-up music box. Cooling the HVC “is like slowing the rate at which that drum rotates”, he says.

A similar mechanism may work in humans, with each word or common phrase having its own chain of neurons, Fee suggests.

The music box in a finch’s brain

GARGLING, sucking and spitting are the unsavoury actions that serious wine lovers say a proper tasting demands. But the full complexity of taste may come from something even more distasteful: mouth bugs. These bacteria help give us the rich flavours of wine, onions and peppers.

It has long been known that smell plays a big part in the perception of flavour, and Christian Starkenmann and his team at Firmenich, a flavour company in Geneva, Switzerland, had previously found that saliva can turn odourless sulphur-containing compounds from fruit and vegetables

into aromatic chemicals called thiols. Now they have shown that bacteria in saliva are responsible.

The team’s sniffing panel could detect odours from the compounds only when extracts were dissolved in saliva. The aromas wafted up after 30 seconds and faded after 3 minutes (Journal of Agricultural and Food Chemistry, DOI: 10.1021/jf801873h).

At least one species of mouth bacteria, Fusobacterium nucleatum, is responsible for the conversion. The team showed this by adding the bacterium to otherwise sterile saliva containing the odourless starting substances. Only when the bacterium was added were the thiols created.

Starkenmann says the compounds could be used to flavour food.

How mouth bugs make food tastier

18 | NewScientist | 15 November 2008 www.newscientist.com

In brief–