commonly used weedkiller turns male frogs into females

Atrazine, one of the most commonly used and controversial weedkillers, can turn male frogs into females, researchers reported on Monday.

The experiment is the first to show such complete effects of atrazine, which had been known to disrupt hormones and which is one of the chief suspects in the decline of amphibians such as frogs around the world.

"Atrazine-exposed males were both demasculinized (chemically castrated) and completely feminized as adults," Tyrone Hayes of the University of California Berkeley and colleagues wrote in the Proceedings of the National Academy of Sciences.

The chemical had been shown to disrupt development and make frogs develop both male and female features -- termed hermaphroditism. This study of 40 male frogs shows the process can go even further, Hayes said.

"Before, we knew we got fewer males than we should have, and we got hermaphrodites. Now, we have clearly shown that many of these animals are sex-reversed males," Hayes said in a statement.

"Atrazine has caused a hormonal imbalance that has made them develop into the wrong sex, in terms of their genetic constitution."

SIMILAR EFFECTS ON HUMANS?

Whether the effects translate to humans is far from clear. Frogs have thin skin that can absorb chemicals easily and they literally bathe in the polluted water.

The European Union banned atrazine in 2004. The finding may add pressure to the United States to more closely regulate the chemical, used widely in agriculture.

"Approximately 80 million pounds (36,287 tonnes) are applied annually in the United States alone, and atrazine is the most common pesticide contaminant of ground and surface water," the researchers wrote.

"Atrazine can be transported more than 1,000 km (621 miles) from the point of application via rainfall and, as a result, contaminates otherwise pristine habitats, even in remote areas where it is not used," they added, citing other researchers.

an asteroid wiped out the dinosaurs

A giant asteroid smashing into Earth is the only plausible explanation for the extinction of the dinosaurs, a global scientific team said on Thursday, hoping to settle a row that has divided experts for decades.

A panel of 41 scientists from across the world reviewed 20 years' worth of research to try to confirm the cause of the so-called Cretaceous-Tertiary (KT) extinction, which created a "hellish environment" around 65 million years ago and wiped out more than half of all species on the planet.

Scientific opinion was split over whether the extinction was caused by an asteroid or by volcanic activity in the Deccan Traps in what is now India, where there were a series of super volcanic eruptions that lasted around 1.5 million years.

The new study, conducted by scientists from Europe, the United States, Mexico, Canada and Japan and published in the journal Science, found that a 15-kilometre (9 miles) wide asteroid slamming into Earth at Chicxulub in what is now Mexico was the culprit.

"We now have great confidence that an asteroid was the cause of the KT extinction. This triggered large-scale fires, earthquakes measuring more than 10 on the Richter scale, and continental landslides, which created tsunamis," said Joanna Morgan of Imperial College London, a co-author of the review.

The asteroid is thought to have hit Earth with a force a billion times more powerful than the atomic bomb at Hiroshima.

Morgan said the "final nail in the coffin for the dinosaurs" came when blasted material flew into the atmosphere, shrouding the planet in darkness, causing a global winter and "killing off many species that couldn't adapt to this hellish environment."

Scientists working on the study analyzed the work of paleontologists, geochemists, climate modelers, geophysicists and sedimentologists who have been collecting evidence about the KT extinction over the last 20 years.

Geological records show the event that triggered the dinosaurs' demise rapidly destroyed marine and land ecosystems, they said, and the asteroid hit "is the only plausible explanation for this."

'red knights' will not overpay for manchester united football club

A group of wealthy supporters looking into a possible bid for football club Manchester United said they would not overpay, and dismissed financial numbers circulating in the media as purely speculative.

The Times reported on Friday that 60 investors have pledged up to 1.5 billion pounds in their bid to seize control of the club. A spokesman for the group said they had received a very good level of interest.

The 'Red Knights', a collection of City figures including former Football League chairman Keith Harris and Goldman Sachs Chief Economist Jim O'Neill, have said they are looking at the feasibility of putting together a bid for the world's third-richest football club.