New Sex Hormone Found

A new human sex hormone has been found, a new study says. The naturally occurring substance could lead to the long-sought male birth control pill, researchers cautiously speculate.

Gonadotropin-inhibitory hormone (GnIH)—first identified in birds about a decade ago—was recently discovered in the hypothalamus of the human brain. The hypothalamus produces hormones that regulate sleep, sex drive, body temperature, and more.

GnIH suppresses another hormone—gonadotropin-releasing hormone (GnRH)—which spurs the release of additional hormones, which prime the body for sex and reproduction. So scientists cautiously suggest that contraceptives based on the newfound hormone could someday be possible.

"That is an idea we've toyed with," said study co-author George Bentley, a biologist at the University of California, Berkeley. But "we don't know enough about it yet."

Louis DePaolo, the U.S. National Institutes of Health's Reproductive Sciences Branch chief, agreed "it's too premature" to consider a male birth control pill.

GnIH has been known in animals since 2000, and it was known that humans have a GnIH gene, but until now it was a mystery whether humans actually produce the hormone and what its role is.

The researchers, however, extracted GnIH from five human hypthalumuses and proved that the it affects nerve cells that produce the GnRH, the fertility-boosting hormone.

Nuclear safety: When positive is negative

WHEN news spread in December 2007 that an ageing nuclear reactor in Canada might shut down for much longer than its scheduled two weeks, the world caught its breath. The reactor, at Chalk River in Ontario, is the world's biggest supplier of radioactive isotopes for medical use, and diagnostic tests for cancer and heart disease were put on hold while radiologists scrambled to find alternative supplies. It was called a crisis. All the while, lay people couldn't help but wonder: did no one foresee this? Did no one think that this half-century-old reactor might someday need to be replaced?

As it happens, not only did someone think about it, they designed and built its successors right next door. Maple 1 and Maple 2 are two brand-new reactors, constructed at a combined cost of over C$350 million ($330 million) specifically to produce medical radioisotopes. A single Maple reactor can supply the world's total current needs; the second one is a back-up to keep the supply flowing during routine repairs.

But the sad truth is that the Maples have never been officially switched on, and the chances are they never will be. This has led to a furious row over who is to blame for this costly and embarrassing debacle. Many in the nuclear industry point the finger at Canada's nuclear regulator. The regulator's view is that the reactors' manufacturer failed to deliver a crucial safety feature that it had promised would underpin the design.

Others blame the Canadian government for killing off the project before crucial technical questions had been resolved; in May 2008 it announced, to everyone's surprise, that the Maples were being shuttered for good. "It makes absolutely no sense to me," says Jatin Nathwani, an engineer at the University of Waterloo, Ontario, who gave evidence to a parliamentary committee now looking into the affair. It's time the Canadian government reversed its decision, says Nathwani: "If the will was there, the Maples could be brought back in six to 18 months, with just one phone call from the prime minister."

Radioisotopes have a vital role to play in modern medicine. They are used in almost 40 million medical procedures each year, mostly for treating and diagnosing diseases such as cancer and heart disease. Over 80 per cent of the diagnostic procedures rely on technetium-99m, a short-lived isotope that is produced by bombarding uranium-235 with neutrons inside a reactor (see diagram).

Deep-sea snail shell could inspire next-gen armour

A deep-sea snail shell's ability to withstand heavy blows could inspire new generation of body armour.

Crysomallon squamiferum, commonly known as the scaly-foot gastropod, was discovered in 1999 in the Kairei "black smoker" field on the Central Indian Ridge, at a depth of 2420 metres.

Christine Ortiz at the Massachusetts Institute of Technology and her colleagues studied the snail's three-layered shell to find out how it defends itself from crab attacks.

To assess the shell's strength and stiffness, they penetrated it with diamond-tipped probe – applying the same amount of force that an attacking crab's claws might use. They then used the data to model the shell's layers and launched a virtual crab attack on it.
Iron hard

It turns out that the snail employs some unique tricks to protect itself. For example, the shell's outermost layer consists of strong particles of iron sulphide created in the hydrothermal vents, each around 20 nanometres across, embedded in a soft organic matrix secreted by the snail. This structure is designed to crack when hit, but in a way that absorbs energy.

Cracks spread only by fanning out around the iron sulphide particles. This "microcracking" not only absorbs energy, it also ensures that larger cracks do not form. What's more, the particles of iron sulphide may blunt and deform intruding claws, the study suggests.

See-Through Goldfish Bred

To create the translucent creature, scientists at Japan's Mie University and Nagoya University crossbred fish that had defects in the gene that regulates pigment, or color.

The resulting mutant fish's organs are all plainly visible, Yutaka Tamaru, a life science researcher at Mie University, said via email.

Tamaru said the fish could act both as a living textbook in biology classes and as a tool for medical researchers.

For instance, scientists could watch in real time how an animal's organs develop. They could also get an inside view of how diseases, particularly tumors, progress in the body.

"As this goldfish grows bigger, you can watch its whole life," Tamaru said.

The translucence doesn't harm the goldfish or shorten its life span, he added.