Science Special News

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The DNA so dangerous it does not exist

Submitted by Marvy: Could there be forbidden sequences in the genome - ones so harmful that they are not compatible with life? One group of researchers thinks so. Unlike most genome sequencing projects which set out to search for genes that are conserved within and between species, their goal is to identify "primes": DNA sequences and chains of amino acids so dangerous to life that they do not exist."It's like looking for a needle that's not actually in the haystack," says Greg Hampikian, professor of genetics at Boise State University in Idaho, who is leading the project. "There must be some DNA or protein sequences that are not compatible with life, perhaps because they bind some essential cellular component, for example, and have therefore been selected out of circulation. There may also be some that are lethal in some species, but not others. We're looking for those sequences."

To do this, Hampikian and his colleage Tim Anderson, also at Boise, have developed software that calculates all the possible sequences of nucleotides - the "letters" of DNA - up to a certain length, and then scans sequence databases such as the US National Institutes of Health's Genbank to identify the smallest sequences that aren't present. Those that don't occur in one species but do in others are termed "nullomers", while those that aren't found in any species are termed primes.

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Black hole found in ancient lair

A black hole has been found inside a compact group of ancient stars known as a globular cluster. Astronomers say the discovery is interesting because many doubted black holes could exist in such locations. Some computer simulations had suggested a newly formed black hole would simply be ejected from the cluster as a result of gravitational interactions. Tom Maccarone, of the University of Southampton (UK), and colleagues report the finding in the journal Nature. It was made using the European Space Agency's XMM-Newton satellite, with follow-up observations on the US space agency's Chandra Space Telescope - both are sensitive to the X-ray light that is emitted when gas consumed by a black hole is torn apart. The international team says its work provides the first convincing evidence that some black holes might not only survive but grow and flourish in globular clusters. What has astonished the scientists is how quickly the black hole was found. "We were preparing for a long, systematic search of thousands of globular clusters with the hope of finding just one black hole," said Dr Maccarone. "But bingo, we found one as soon as we started the search. It was only the second globular cluster we looked at."

The black hole is located in a globular cluster associated with a galaxy named NGC 4472, some 55 million light-years away. Globular clusters are among the oldest structures in the Universe. They contain thousands to millions of stars packed into a region of space just a few tens of light-years across. These high densities should lead to frequent interactions and even collisions; and some models have suggested that large black holes - several hundred times the mass of our Sun - could develop in the densest inner regions of clusters.

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"UFO crash" reported in South Africa

Submitted by Telemachos: A UFO was sighted at Lephalale, where it was described as a strange object "on an orange cloud, singing like a million turbines" - hitting the earth with a bang at 04:33 on Saturday. That's according to Leonie Ras, the administrative manager of Lephalale (Ellisras) who witnessed the spectacle at her daughter's farm just east of the town on Saturday morning. "I was lying on my bed reading SMS-messages when I heard a noise like an Airbus aircraft firing up its motors." "It was raining but there was no thunder or lightning. The noise grew louder and eventually it sounded like a million turbines screaming in unison," Ras said. She walked to the bedroom window and saw the clouds taking on a bright orange-red colour. "Suddenly, a bright object plunged from the clouds to the earth, at a terrible speed, and hit the ground with an almighty bang." "It looked like Haley's comet, round in the front and with an orange-red tail following behind." When the UFO hit the ground the low-lying clouds went orange.

"It was so exceptional that I started crying. I wished my children and grandchildren could have seen it. I had not been drinking and I was in full control of my faculties," she said. She calculated that the object must have hit the ground near Beauty, between the Tambotie and Palele rivers. Cobus Nel, her son-in-law, who was also in the house, woke up from the commotion. "I woke up to a terrible rumbling, followed by a sound like an explosion. I woke my wife up, so that she could also listen, because the rumbling lasted more than a minute, becoming louder, then we heard the bang," Nel said. Lephlale's fire service, police and disaster control centres seemed to have slept through the commotion.

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Human brain evolution slows to a crawl

The human brain underwent explosive growth after we split from our chimp cousins, but the pace of evolutionary change among the thousands of genes expressed in brain tissue has since slowed, says a new study in PLOS Biology. The researchers involved speculate that the higher complexity of the biochemical network in the brain places strong constraints on the ability of most brain-related genes to change. "We found that genes expressed in the human brain have in fact slowed down in their evolution, contrary to some earlier reports," says study author Chung-I Wu, at the University of Chicago. "The more complex the brain, it seems, the more difficult it becomes for brain genes to change. Calibrated against the genomic average, brain-expressed genes in humans appear to have evolved more slowly than in chimpanzees." To gauge the speed with which both humans and chimpanzees accumulated small differences in gene sequences, Wu and co-researchers in Asia decided to sequence several thousand genes expressed in the brain of the macaque monkey and compare them with available genomic sequences from human, chimpanzee, and mice. What they found was that the "more advanced" species had faster overall rates of evolution.

On average, the genes from humans and chimpanzees changed faster than genes from monkeys, which changed faster than those from mice. They explained the trend as a correlate of smaller population size in the more advanced species. Species with smaller population size can more easily escape the harsh scrutiny of natural selection. When they compared the pace of evolution among genes expressed in the brain, however, the order was reversed. When calibrated against the genomic average, brain genes in humans evolved more slowly than in other primates, which were slower than mice.

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Lost lakes of Titan are found at last

Lakes of methane have been spotted on Saturn's largest moon, Titan, boosting the theory that this strange, distant world bears beguiling similarities to Earth, according to a new study. Titan has long intrigued space scientists, as it is the only moon in the Solar System to have a dense atmosphere -- and its atmosphere, like Earth's, mainly comprises nitrogen. Titan's atmosphere is also rich in methane, although the source for this vast store of hydrocarbons is unclear. Methane, on the geological scale, has a relatively limited life. A molecule of the compound lasts several tens of millions of years before it is broken up by sunlight. Given that Titan is billions of years old, the question is how this atmospheric methane gets to be renewed. Without replenishment, it should have disappeared long ago. A popular hypothesis is that it comes from a vast ocean of hydrocarbons. But when the US spacecraft Cassini sent down a European lander, Huygens, to Titan in 2005, the images sent back were of a rugged landscape veiled in an orange haze.

There were indeed signs of methane flows and methane precipitation, but nothing at all that pointed to any sea of the stuff. But a flyby by Cassini on July 22 last year has revealed, thanks to a radar scan, 75 large, smooth, dark patches between three and 70 kilometers across (two and 42 miles) across that appear to be lakes of liquid methane, scientists report on Thursday. They believe the lakes prove that Titan has a "methane cycle" -- a system that is like the water cycle on Earth, in which the liquid evaporates, cools and condenses and then falls as rain, replenishing the surface liquid.

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Calf with two faces born at Va. farm

One of the newest arrivals at ***k Heldreth's dairy farm is drawing crowds. A calf with two faces was born Dec. 27 at Heldreth Dairy Farm, and word has spread in southwest Virginia as residents flock to his farm. The animal is normal from its tail until its unusually large head. The calf breathes out of two noses and has two tongues, which move independently, according to Heldreth. There appears to be a single socket containing two eyes where the heads split."It's the craziest thing I've ever seen," the dairyman said.During the calf's birth, Heldreth said he first thought there were two calves.The calf has two lower jaws, but only one mouth. Heldreth feeds her through a tube, and acknowledges he probably can't maintain that feeding schedule for long.The calf was the product of artificial insemination, which was supposed to create a genetically superior specimen. "Genetically, this is one of my better calves," he said.Bob James, a professor in the dairy science department at Virginia Tech and Heldreth's former teacher, said such births are unusual."In my 25 years, I've seen it maybe two or three times, but it's pretty rare," he said.

James said the abnormality could be caused by a developmental problem or a genetic quirk.According to MedicineNet.com, the condition is called diprosopus. It happens when twins start to form and don't completely separate. In most cases, the twins are completely fused with one set of limbs, but part or all the face is duplicated.Heldreth said the calf doesn't appear to have any other physical ailments or complications."It's as healthy as can be," he said.Heldreth expects many more people will be curious enough to stop by.

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Meteorite shoots through house roof

Submitted by Irishdish: The mysterious object that shot through the roof of a two-story home earlier this week was identified by scientists as a meteorite, police said Friday. But the fate of the extraterrestrial mass, likely formed with the solar system some 4.6 billion years ago, has emerged as another unknown in the case of the second known meteorite to fall in New Jersey.Its new owners, a married couple with a son, expressed some interest in putting the meteorite on a small-scale tour so local schoolchildren could see it, said Jeremy Delaney, a Rutgers University meteoriticist who was among four scientists who identified the object for police and later met the family.Eventually the family will have to decide whether to keep the meteorite, give it to an academic institution such as a museum or sell it to a collector.What's for sure is that the object will be in high demand.Rarely on landings do meteorites come in contact with people. So when they do, the space artifacts are connected with a story that generates interest all around.The American Museum of Natural History in New York City and the Smithsonian Institution in Washington D.C., both of which have extensive meteorite collections, likely will have interest, Delaney said.Depending on the rarity of a given meteorite, researchers sometimes spend several years looking at the same chunk that fell from space."By looking at these objects, we have the ability to explore our deep, deep past," Delaney said.

"Meteorites have given scientists clues about life on Mars and the rest of our solar system."New Jersey's only other known meteorite, weighing an ounce, fell in Deal in 1829.The precise research value of New Jersey's newest meteorite won't be known unless it ends up in the hands of scientists who would study its composition.But Delaney said the Freehold meteorite might be of some interest to researchers because it is rich in metals, a sign that it came from the deep interior of an asteroid."We all want to know where it's from and you won't get that until you do some analysis," said Peter Elliott, a Colts Neck metallurgist who also helped identify the meteorite.

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Hubble makes 3D dark matter map

Astronomers have mapped the cosmic "scaffold" of dark matter upon which stars and galaxies are assembled. Dark matter does not reflect or emit detectable light, yet it accounts for most of the mass in the Universe. The study, published in Nature journal, provides the best evidence yet that the distribution of galaxies follows the distribution of dark matter. This is because dark matter attracts "ordinary" matter through its gravitational pull. Scientists presented details of their research during a news conference here at the 209th meeting of the American Astronomical Society (AAS) in Seattle, Washington. It involved nearly 1,000 hours of observations with the Hubble Space Telescope. According to one researcher, the findings provide "beautiful confirmation" of standard theories to explain how structures in the Universe evolved over billions of years. Ordinary matter - gas, stars, planets and galaxies - makes up just one-sixth of all matter in the Universe. The remainder is unseen. While previous studies of dark matter relied on simulations, this one details its large-scale distribution in 3D. For astronomers, the challenge of mapping the Universe has been described as similar to mapping a city from night-time aerial snapshots showing only street lights.

Dark matter is invisible, so only the luminous galaxies can be seen directly. The new images are equivalent to seeing a city, its suburbs and country roads in daylight for the first time. Yet puzzling discrepancies remain. The map of mass distribution is based on measurements of about half a million distant galaxies. Lead author Richard Massey and his colleagues used a technique called weak gravitational lensing to detect the dark matter. To reach us, the light from galaxies has to pass through intervening dark matter.

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