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Key genetic differences among people revealed
A NEW way of comparing DNA has turned up surprising genetic differences among normal, healthy people, researchers have said. The researchers found — by accident — that some people are missing large chunks of DNA, while others have extra copies of stretches of DNA.
Writing in the journal Science, the researchers have dubbed these differences “copy number polymorphisms.” They are found in genes linked with cancer risk, with how much people eat and with reactions to drugs.
“Thus, a relationship between CNPs and susceptibility to health problems such as neurological disease, cancer, and obesity is an intriguing possibility,” the researchers wrote in their report.
The team at Cold Spring Harbor Laboratory in New York, the Karolinska Institute in Stockholm, Sweden and elsewhere used a new kind of DNA test called Representational Oligonucleotide Microarray Analysis or ROMA.
“It can detect differences in DNA from any two sources,” said Cold Spring Harbor spokesman Peter Sherwood.
The researchers were looking for genetic differences linked with cancer.
“As a control in the cancer experiment they compared normal to normal DNA, expecting it to be pretty much the same,” Sherwood said in a telephone interview.
“They detected more than 70 of these large chunks of DNA that were altered in normal human cells.”
These were large differences that have not been reported before — involving much more DNA than so-called single nucleotide polymorphisms, which are well-known single-letter changes in the A, C, T, G nucleotide code that makes up DNA.
“They looked at blood and normal tissues from 20 people from different geographical regions. They found that probably on average about five of the people would have the same difference, the same CNP,” Sherwood said.
Everyone has two copies of each chromosome, except for the X and Y chromosomes that separate men from women. The researchers found that each of their healthy volunteers had just one copy of each CNP.
“If they happen to marry and have children with someone who has the same CNP, maybe the children will be affected,” Sherwood said.
The researchers also found possible mistakes in the map of the human genome published by the Human Genome Project.
Neutrinos ‘topple’ matter theory
A study involving the world’s largest underground tank of water has concluded neutrino particles are a mystery.
Neutrinos do not interact very much with matter, but they can be detected as flashes of light in the 50,000-tonne Super-Kamiokande detector in Japan. Many of them come from the Sun while others are formed in the Earth’s atmosphere by cosmic ray impacts.
The new data confirms that they change as they travel through space which is contrary to current theories of matter. For five years a team of more than 100 physicists from around the world have studied the flashes of light detected by the photomultiplier tubes that line the Super-K tank, a facility sited in the Kamioka Mozumi mine. This so-called Cerenkov radiation is given off by charged particles created in the tank by the passage of neutrinos.
Neutrinos are an enigma. They interact only very weakly with normal matter; billions of them come streaming out of the Sun’s core unhindered by the mass of the star. And some neutrinos are created by high-energy cosmic rays from deep space striking air molecules in the Earth’s upper atmosphere. These neutrinos have proven very profitable to study.
The latest research confirms the cosmic-ray produced neutrinos come in two “flavours”, called electron-type and muon-type. According to current ideas, neutrinos should only be able to change their flavours if they have mass, but the Standard Model does not allow for this. After the first indications that neutrinos could oscillate, there remained a few unusual theories that roughly explained the phenomenon. But these ideas have now been ruled out by the latest results, says the Super-K Collaboration.
China’s second space probe
China has successfully launched a probe as part of a Sino-European partnership aimed at improved monitoring of magnetic storms and other space hazards, state media said.
State television said the “Probe-2” satellite — the second in the “Double Star Program” — was launched from the centre in Taiyuan in China’s northern province of Shanxi.
The probe, launched aboard a Long March 2C/SM rocket, successfully gained orbit about 30 minutes, it said.
The official Xinhua news agency said it would coordinate with an earlier probe on a mission to improve space mission safety, and also with European Space Agency satellites on joint research.
The satellite was jointly designed by the China Aerospace Science and Technology Corporation and research bodies linked to the European Space Agency, state media have said. — Sci-tech World Report
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