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SCIENCE UPDATE
Cloned human embryo develops into stem cells
South Korean scientists have created cloned human embryos to generate stem cells, touted as the miracle material that may one day reverse diabetes, cancer, Alzheimer’s and other disorders.
The technique is aimed at disease therapy, not at creating a cloned baby, the scientists said, and in any case has many hurdles to clear before it can ever be used for humans.
Stemcells are nascent cells that can be coaxed by chemical signals in the body into becoming different kinds of tissue.
By far the most versatile of these — “pluripotent” in scientific jargon — are stem cells that come from embryos, for these cells can grow into almost any part of the body.
The dream is one day to use stem cells to grow replacement tissue in a lab dish, such as brain cells, skin, liver, a kidney, that could be used for human transplants.
But, as decades of conventional organ transplants have shown, transplanted tissue is invariably rejected as foreign by the patient’s immune system if it comes from another body.
To get around this, the search is on for cloned embryonic stem cells — stem cells which have exactly the same DNA as the patient, and thus would be accepted by his or her body as friendly rather than hostile tissue.
This is the achievement reported on Feb 12 by a team of researchers led by Woo Suk Hwang of Seoul National University.
“Because these cells carry the nuclear genome of the individual, after differentiation they could be expected to be transplanted without immune rejection for treatment of degenerative disorders,” Woo said.
“Our approach opens the door for the use of these specially developed cells in transplantation medicine.”
The study was published online by the US journal Science ahead of a meeting in Seattle of the American Association for the Advancement of Science (AAAS).
The South Korean team used the classic cloning technique, pioneered in Dolly the Sheep, which is to take an egg and remove the nucleus, which contains virtually all of the DNA code for programming the egg into a human being.
They then replaced the nucleus with one taken from an adult non-reproductive cell, fused them together and then cultured the egg in a warm nutrient bath so that it divided and developed into an early embryo.
Layered rock on Red Planet
Nasa geologists seeking signs that life once existed on Mars are “excited” about layered rocks photographed by the Mars rover Opportunity, the National Aeronautics and Space Administration said.
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“Scientists are excited to see new details of layered rocks in Opportunity Ledge,” Nasa’s Jet Propulsion Laboratory in Pasadena, California, said in a statement.
“In previous panoramic camera images, geologists saw that some rocks in the outcrop had thin layers, and images sent to Earth (Monday) now show that the thin layers are not always parallel to each other like lines on notebook paper.
“Instead,” said the lab, “if you look closely at this image from an angle, you will notice that the lines converge and diverge at low angles. These unparallel lines give unparalleled clues that some moving current, such as volcanic flow, wind, or water, formed these rocks.”
Nasa has always said that any sign of past water on Mars would be a good indication that life once existed on the red planet.
The quest for signs of water is a primary mission of Opportunity, which landed on Mars at the end of January, and of its twin, Spirit, which landed on the other side of the planet about three weeks earlier.
Huge cosmic diamond
Twinkling in the sky is a diamond star of 10 billion trillion trillion carats, astronomers have discovered.
The cosmic diamond is a chunk of crystallized carbon, 1,500km across, some 50 light-years from the Earth in the constellation Centaurus.
It’s the compressed heart of an old star that was once bright like our Sun but has since faded and shrunk.
Astronomers have decided to call the star “Lucy,” after the Beatles song, “Lucy in the Sky with Diamonds.”
“You would need a jeweller’s loupe the size of the Sun to grade this diamond!” says astronomer Travis Metcalfe of the Harvard-Smithsonian Center for Astrophysics, who led the team of researchers that discovered it.
The diamond star completely outclasses the largest diamond on Earth, the 530-carat Star of Africa which resides in the Crown Jewels of England. The Star of Africa was cut from the largest diamond ever found on Earth, a measly 3,100-carat gem.
Technically known as BPM 37093, it is actually a crystallised white dwarf. A white dwarf is the hot core of a star, left over after the star uses up its nuclear fuel and dies. It is made mostly of carbon. For more than four decades, astronomers have thought that the interiors of white dwarfs crystallized, but obtaining direct evidence became possible only recently.
We figured out that the carbon interior of this white dwarf has solidified to form the galaxy’s largest diamond,” says Metcalfe.
Astronomers expect our Sun will become a white dwarf when it dies 5 billion years from now. Some two billion years after that, the Sun’s ember core will crystallise as well, leaving a giant diamond in the centre of our Solar System. — Sci-tech World Report
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