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Nanotech shows how brain cells chatter
FRENCH scientists using an innovative microscopic scanning technique say they have discovered that nerve cells almost buzz with molecular agitation when they communicate with each other.
The work sheds light on how cells operate at the synapse — the minute gap between neurons, as nerve cells are called.Neurons communicate by sending chemical signals across the synapse, which then latch on to specific targets, known as receptors, on the membrane of the adjoining cell.
The chemicals activate an electrical signal in that cell, which then sends on a chemical signal to its neighbour, and so on down the line, eventually triggering the desired response or movement in the finger, hand, limb or other organ.
Until now, little was known about receptor movement, and it was thought that these vital “locks” that open to the heart of the cell were largely static.
But nanotechnology, harnessed to a video camera by French researchers, shows the receptors to be extraordinarily active and that they even move around dynamically on the membrane surface.
The discovery is important, because it highlights the complex, highly mobile mechanism by which a receiving cell is able to detect just a single molecule.
The team, led by Antoine Triller, head of an Inserm unit that specialises in synapse research, and Maxime Dahan, of the Kastler Brossel Laboratory at Paris’s Ecole Normale Superieure, publishes its work in Friday’s issue of Science, the US scientific weekly.
Their observations were made on spinal cord tissue from rats, and used a probe called quantum dots, fluorescent semiconductors, with a cadmium-selenium core and a zinc sulphide shell, to tag receptors for glycine, a key synapse signalling chemical.
The “dots” measure just five to 10 billionths of a metre across, and are just a quarter of the smallest nanoparticle tracers used so far. Those particles, made of gold or latex, range from 40 to 500 billionths of a metre, which means they are too big to reveal the single-molecule properties of living cells.
The movement given by the fluorescing quantum dots was filmed in real time, and for long durations, using a videomicroscope.
Dinosaurs got cancer
Many dinosaurs had cancer, researchers have discovered.
Their tumours were like those of human patients, showing that cancer has been around, essentially unchanged, for a very long time. “Diseases look the same independent of what critter is affected,” says radiologist Bruce Rothschild of the Northeastern Ohio Universities College of Medicine in Rootstown.
Rothschild’s team travelled North America with a portable X-ray machine, scanning 10,000 dinosaur vertebrae from more than 700 museum specimens. They looked at such well-known dinosaurs as Stegosaurus, Triceratops and Tyrannosaurus.
Only one group, the hadrosaurs, or ‘duck-billed dinosaurs’, suffered from cancer1. The team found 29 tumours in bones from 97 individuals of this herbivorous group from the Cretaceous period, about 70 million years ago.
It’s not known for certain what made the hadrosaurs sick, although Rothschild points out that they ate conifers, which are high in carcinogenic chemicals. The structure of their bones also suggests they were warm-blooded, which might have increased their cancer risk.
The commonest growths were hemangiomas, benign tumours of the blood vessels that are present in about 10 per cent of humans. “If I showed [the dinosaur bones] to a pathologist, he’d make the same diagnosis,” says Rothschild.
The 3.5 metre species Edmontosaurus was most cancer-prone and was the only one with a malignant tumour. About 3% of its bones contained a lump of some sort.
HIV-friendly proteins identified
US researchers have identified a series of proteins that enable HIV to bypass the human body’s natural anti-viral defenses and multiply, a discovery they say could lead to new treatment drugs for HIV and AIDS.
“We’ve discovered a new link in the chain that allows the HIV to overcome the cellular resistant factor and to infect human cells,” Doctor Xiao-Fang Yu, associate professor at Johns Hopkins Bloomberg School of Public Health, wrote in the on-line edition of Science magazine.
“By identifying the proteins involved in this process, we may be able to develop new drugs and therapies for preventing HIV infection,” wrote Xiao-Fang Yu, who headed a research team that identified the proteins through a series of complex laboratory experiments.
According to the study, the AIDS virus contains a viral infection factor essential to escaping the human body’s natural anti-viral agent.
To circumvent this protective agent, HIV acts in conjunction with a group of proteins to modify and disable the anti-viral agent, said the research team.
Ancient carved ‘faces’ found
A keen-eyed archaeologist claims to have found some of the oldest artwork ever, carved faces 200,000 years old.
The human images were found in 2001 by Pietro Gaietto on an expedition through the Borzonasca district of Italy.
He claims the rock has been sculpted into faces that look in opposite directions; one is bearded with what Gaietto calls an “expressive face”.
If this is genuine, the artist would have been an extinct human species that died out about 150,000 years ago.
Gaietto believes the sculpture is 200,000 years old, and would have been used in rituals. — Dawn Science Dotcom
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