Crabs caught spying on rivals' love claws

Male fiddler crabs spy on their competitors to work out when a potential female mate is around, Australian researchers have found.

Their findings are reported today in Biology Letters.

"Males will use other males as female detectors," says behavioural ecologist Richard Milner of the Australian National University in Canberra.

"They'll eavesdrop on other males' courtship displays to detect the presence of a female."

Milner carried out the research for his PhD under the supervision of Associate Professor Patricia Backwell and Professor Michael Jennions.
Long arm of love

Male fiddler crabs have a large specialised claw that they use to fight and wave around to attract mates.

"When a female approaches a group of males they'll all start waving in synchrony and they'll all start trying to attract her," says Milner.

But knowing when females are around in the first place can be tricky because females are well camouflaged.

"The males are ridiculously conspicuous but the females look very bland," says Milner.

Milner wanted to see if males would use waving by other males as a sign there was a female around and start waving before they could actually see the female.

This would enable them to detect the presence of a female earlier than they otherwise would.

Study finds US cigs highest in chemicals

Americans inhale more cancer-causing agents with their cigarettes, while smokers in Canada, Britain and Australia get less, US researchers report.

Their study also demonstrated that the amounts of these carcinogens in a smoker's cigarette butts directly correlated with tell-tale compounds in the smoker's urine.

The study, published in the June issue of Cancer Epidemiology, Biomarkers and Prevention, could help researchers trying to trace the harmful effects of smoking.

"We know that cigarettes from around the world vary in their ingredients and the way they are produced," says Dr Jim Pirkle of the US Centers for Disease Control and Prevention, who heads a lab using a mass spectrometer to measure levels of chemicals in people's bodies.

"All of these cigarettes contain harmful levels of carcinogens, but these findings show that amounts of tobacco-specific nitrosamines differ from country to country, and US brands are the highest in the study," says Pirkle.

CDC's David Ashley and colleagues did in-depth tests using 126 smokers in the United States, Canada, Britain and Australia.

"Seventeen eligible cigarette brands (between three and five brands from each country) were selected on the basis of national sales and nicotine yield to identify popular brands with a range of ventilation," the researchers write. Ventilation is how much air is mixed in with the smoke from the cigarette as it is inhaled.

The volunteers had their saliva and urine tested and also turned over their used cigarette butts to the researchers.

Caffeine addicts get no real perk

Caffeine addiction is such a downer that regular coffee drinkers may get no real pick-me-up from their morning cup, according to a British study.

Researchers from Bristol University found that drinkers develop a tolerance to both the anxiety-producing and the stimulating effects of caffeine, meaning that it only brings them back to baseline levels of alertness, not above them.

"Although frequent consumers feel alerted by caffeine, especially by their morning tea, coffee, or other caffeine-containing drink, evidence suggests that this is actually merely the reversal of the fatiguing effects of acute caffeine withdrawal," write the scientists, led by Professor Peter Rogers.

The team asked 379 adults - half of them non/low caffeine consumers and the other half medium/high caffeine consumers - to give up caffeine for 16 hours, and then gave them either caffeine or a dummy pill known as a placebo.

Participants rated their levels of anxiety, alertness and headache. The medium/high caffeine consumers who got the placebo reported a decrease in alertness and increased headache, neither of which were reported by those who received caffeine.

But measurements showed that their post-caffeine levels of alertness were actually no higher than the non/low consumers who received a placebo, suggesting caffeine only brings coffee drinkers back up to "normal".

The researchers also found that people who have a genetic predisposition to anxiety do not tend to avoid coffee.

In fact, people in the study with a gene variant associated with anxiety tended to consume slightly larger amounts of coffee than those without it, Rogers writes in a study in the Neuropsychopharmacology journal, published by Nature .

Velvet worm's deadly slime revealed

Scientists have discovered that the ancient velvet worm uses a glue unlike anything seen before in nature.

The glue, which is easy to replicate, could have a range of applications, such as a medical glue for open wounds and burns.

CSIRO Entomology scientist Dr Victoria Haritos, who uncovered the worm's secret, says "it's a case of using disorder as a weapon."

Haritos who is looking for new types of silk, milked an Australian species of velvet worm called Euperipatoides rowelli.

She found the silk produced by the worm isn't silk at all - it's the exact opposite.

Silk is made up of well ordered, structured proteins forming molecules with the molecular shape determined by the way the proteins amino acids are sequenced.

According to Haritos the sticky slime produced by the velvet worm is neither structured nor well ordered.
Getting slimed

The worm rapidly spits out slime from tubes on either side of its head. This quickly covers it prey and immediately begins to set hard, going very stringy and rope-like.

"It gets harder and harder and very sticky, immobilising the victim," says Haritos.

She says the key ingredient in the slime is water. "In fact the slime consists of 90% water and just 3% to 5% protein."

"As long as the proteins are covered in a film of water, they remain inert, the watery sheaths keeping the structure open and random. This prevents the protein molecules from interacting with one another.

"But once it hits the victim, this thin film of water quickly evaporates letting the proteins get tangled together to form tight chemical bonds and making them go sticky and hard."

The evaporation process is helped by the prey's waxy, water-repellent shell.

Stem cells turn into seek-and-destroy cancer missiles

GENETICALLY modified stem cells are to be injected into the brains of cancer patients, where they will convert an inactive cancer drug into a potent and targeted tumour-killing agent.

Stem cells are strongly attracted towards cancer cells, so it is hoped that as well as homing in on the main tumour, they will also be drawn to secondary growths, or metastases. This will enable higher doses of drug to be delivered to cancer cells while minimising the risk of side effects in the rest of the body.

A team led by Karen Aboody at the City of Hope Beckman Research Institute in Duarte, California, used neural stem cells originally derived from human fetuses which had been genetically engineered to produce cytosine deaminase. This is an enzyme that converts a drug called 5-fluorocytosine (5-FC) into an active chemotherapy drug, 5-fluorouracil (5-FU), but only in the immediate vicinity of the stem cell.

The team then injected the modified stem cells into the brains of mice with glioma, an aggressive form of brain cancer. The animals were subsequently given 5-FC. Treated mice saw a 70 per cent reduction in tumour mass compared with untreated animals. "In effect, we're allowing a much higher dose of chemo to be localised to the tumour site," says Aboody, who presented the results in May at an international brain tumour conference in Travemünde, Germany.

The US Food and Drug Administration has granted Aboody approval to carry out a safety trial of the therapy in up to 20 patients with recurrent glioma, for whom life expectancy is just three to six months. The stem cells will be injected into the tumour cavity following surgery to reduce its mass, and then given four days to home in on any remaining cancer cells. Patients will then be treated with daily 5-FC for one week.

All you need to know about the hurricane season

The North Atlantic hurricane season officially began on 1 June, and the US National Hurricane Center expects it to be a busy one. It forecasts a 70 per cent chance of eight to 14 storms reaching hurricane strength, and three to seven becoming dangerous "major" hurricanes of category 3 and above. Reaching the upper end of that range would make 2010 one of the most active hurricane seasons on record. What does that mean for residents of the Gulf and Atlantic coasts of the US, worried about oil spreading from the Deepwater Horizon blowout?

Wasn't 2005 "a once in a century" hurricane year? Why are a similar number of storms forecast this year?

If hurricane numbers were purely random, there would be a 1 in 100 chance of a hundred-year storm being followed the next year by a second hundred-year storm. However, the number of hurricanes is far from random.

Hurricane formation in the north Atlantic and the Caribbean is linked to a cycle called the Atlantic Multidecadal Oscillation. In a cycle lasting 20 to 40 years, sea-surface temperatures from Greenland to the equator rise and fall by about 0.5 °C. During the warm phases, about twice as many weak tropical storms grow into severe hurricanes as during the cooler phases.

The last rise in sea-surface temperatures and hurricane numbers came in the mid-1990s, so the average number of storms now is above the long-term average, and well above the relatively low numbers from the 1960s to the mid-1990s. The number of hurricanes was higher than average from the 1940s to the early 1960s. Those shifts roughly kept pace with the sea-surface temperature cycle.

shake nature's constants

The basic constants of nature aren't called constants for nothing. Physics is supposed to work the same way across the universe and over all of time. Now measurements of the radio spectra of a distant gas cloud hint that some fundamental quantities might not be fixed after all, raising the possibility that a radical rethink of the standard model of particle physics may one day be needed.

The evidence comes from observations of a dense gas cloud some 2.9 billion light years away which has a radio source, the active supermassive black hole PKS 1413+135, right behind it. Hydroxyl radicals in the gas cloud absorb the galaxy's radio energy at certain wavelengths and emit it again at different wavelengths. This results in so-called "conjugate" features in the radio spectrum of the gas, with a dip in intensity corresponding to absorption and an accompanying spike corresponding to emission.

The dip and spike have the same shape, which shows that they arise from the same gas. But Nissim Kanekar of the National Centre for Radio Astrophysics in Pune, India, and colleagues found that the gap in frequency between the two was smaller than the properties of hydroxyl radicals would lead us to expect.

The gap depends on three fundamental constants: the ratio of the mass of the proton to the mass of the electron, the ratio that measures a proton's response to a magnetic field, and the fine-structure constant, alpha, which governs the strength of the electromagnetic force. The discrepancy in the size of the gap thus amounts to "tentative evidence" that one or more of these constants may once have been different in this region of space, Kanekar says.

Space taxi reaches orbit in first flight test

A private company has launched a new rocket that may carry NASA astronauts to orbit after the space shuttle's retirement.

SpaceX's Falcon 9 rocket lifted off from Cape Canaveral, Florida, on Friday at 1845 GMT (1445 EDT), reaching orbit 9 minutes later.

The rocket lofted an uncrewed mockup of SpaceX's Dragon capsule, which is designed to one day carry both crew and cargo to orbit. "This has been a good day for SpaceX and a promising development for the US human space flight programme," said Robyn Ringuette of SpaceX in a webcast of the launch.

In a teleconference with the media on Thursday, SpaceX's CEO, Paypal co-founder Elon Musk, said he would consider the flight 100 per cent successful if it reached orbit. "Even if we prove out just that the first stage functions correctly, I'd still say that's a good day for a test," he said. "It's a great day if both stages work correctly."

SpaceX hopes to win a NASA contract to launch astronauts to the International Space Station using the Falcon 9. US government space shuttles, which currently make these trips, are scheduled to retire for safety reasons at the end of 2010.

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Immune system could be used to test for TB

Two immune system molecules could form the basis of a new test to quickly detect whether tuberculosis is dormant or active and infectious, say US researchers.

Dr Jason Stout of Duke University, presented his findings at the current American Thoracic Society meeting in New Orleans.

"A rapid test that could tell the difference between latent and active tuberculosis would be a major step forward," says Stout.

He says doctors could more quickly treat active infections, helping to limit the spread of the disease.

Current blood tests can distinguish between people who are infected with TB and those who are not but they cannot tell whether an infection is active or dormant. It takes a culture test that grows the TB bacilli to show if it is active or not, and that can take weeks.

Stout and colleagues collected blood samples from 71 people with active TB, latent TB or no infection at all.

They added a bit of TB bacteria to the blood samples to stimulate an immune response, then measured the activity of 25 immune signalling chemicals called cytokines to try to identify a pattern that could be used as a signature of active TB infection.

"We found that a pattern of two cytokines, called MCP-1 and IL-15, was reasonably good at differentiating between persons sick with TB and persons infected but not sick," says Stout.

A third cytokine called IP-10 also showed promise at sorting between people who are infected and those who are not.

Stout says other studies have pointed to these three cytokines individually as possible TB markers, but his is the first to put all three together as a possible TB test.

"These findings could lead to earlier diagnosis of active tuberculosis, which could be beneficial for both the sick person and others around her or him who might be spared from infection," says Stout.

Tuberculosis killed 1.8 million people in 2008, or nearly 5,000 people a day. It is caused by the Mycobacterium tuberculosis bacteria. More than 2 billion people, or about a third of the world's population, are thought to be infected.

It is not only a scourge in poor countries but also in the West, where it has flared anew in the last 20 years because of AIDS, which weakens the immune system.

TB can be cured with antibiotics, but they need to be taken daily for months to be effective.

Because people often skip doses, multiple drug resistant forms are spreading and the World Health Organization says the hard-to-treat infection is spreading.