For the first time, scientists have derived and cultured embryonic stem (ES) cells from rats, paving the way for genetically engineered rats that would more accurately model some human diseases than the currently available genetically engineered mice. Two collaborating teams developed a new approach to derive the ES cells, using a new cocktail of molecules to protect their precious pluripotency, the ability to differentiate into any type of cell. “This is a major development in stem cell research because we know that rats are much more closely related to humans than mice in many aspects of biology. The research direction of many labs around the world will change because of the availability of rat ES cells,” says Qilong Ying [Xinhua], who led one of the teams.
ES cells from mice have been available since 1981, and different researchers have created hundreds of different strains of “knock-out” mice—ones raised from ES cells in which certain genes are silenced to make apparent the genes’ functions. With mice, ES cells were grown with a mixture of growth signals to make them divide without differentiating. But transferring the same technique to rats and other mammals proved surprisingly difficult. To the great frustration of researchers, stem cells isolated from rat embryos and cultured with growth signals would quickly lose their pluripotency. The new strategy, reported in two studies in Cell [subscription required], involves growing the ES cells in a mixture of three key molecules that block the signals that normally induce differentiation. “Our discovery was that if you want to maintain cells in the undifferentiated state, you must block signals, not activate them,” says Ying… By repressing differentiation, the researchers could hold the cells in what they call a “ground state,” a blank slate ready to turn into any tissue in the body [Science News].
In several years police officers may have laser or microwave guns to point at miscreants, according to the Justice Department’s research and development agency. These nonlethal weapons build on knowledge gained from the Pentagon’s controversial Active Denial System (ADS) – first demonstrated in public last year, which uses a 2-metre-[wide] beam of short microwaves to heat up the outer layer of a person’s skin and cause pain. Like the ADS, the new portable devices will also heat the skin, but will have beams only a few centimetres across. They are designed to elicit what the Pentagon calls a “repel response” – a strong urge to escape from the beam [New Scientist]. But the idea of giving cops a tool capable of instantly inflicting pain from across a town square is raising protests from human rights advocates.
The Justice Department is working on two separate weapons. One, the Personnel Halting and Stimulation Response, or PHaSR, uses an infra-red laser to heat a patch of skin about 4 inches in diameter, and pairs that heat with another bright laser that dazzles the eyes. The PHaSR looks like a bulky rifle, and law enforcement officials say that a cheap, portable version could be very useful to police and prison guards. Sid Heal, formerly a Commander in the Los Angeles Sheriff’s Department (and before that a Marine) , has long been an advocate of non-lethal weapons and thinks the new devices might have potential. “Needless to say, the “market” is so vacant with alternatives that ANYTHING is going to be appealing at this point” [Wired News], says Heal.
When a honeybee is given a dose of cocaine, it gets overexcited about poor-quality food and performs overenthusiastic dances to communicate with its hivemates, according to an odd new study that got bees hooked on drugs. The research found similarities between honey bees and humans, in that they are both are driven by rewards and both have their judgment altered by cocaine. “This is the first time that it’s been shown that cocaine has been rewarding to an insect” [Reuters], says study coauthor Andrew Barron.
After a honeybee has been out foraging for food, it returns to the hive and tells the other bees what it found by means of a “waggle dance” that describes the location and quality of the food source. But after dabbing low doses of cocaine on the bees’ backs before they went out, the researchers observed that when they returned they were more likely to dance for their nest mates, and performed particularly vigorous routines explaining where the food was located [The Guardian]. They performed these exuberant dances even when the food source that the researchers provided was a weak sugar water solution that didn’t merit the hive’s attention.
As the year 2008 draws to a close, the world’s timekeepers are giving us a little extra time to wrap up loose ends: They’re giving us one extra second, to be precise. The “leap second” must be added to keep atomic clocks ticking along in time to the planet’s rotation. So at precisely 23:59:60 at Greenwich, England, on New Year’s Eve, there will be a one-second void before the onset of midnight and the start of the New Year…. By the time the transition from 2008 to 2009 arrives in North America the Leap Second will have already been inserted into the world’s timescale [SPACE.com].
The adjustment is necessary because we have two different ways of measuring time. Traditionally, humankind has reckoned time by the spin of the Earth and its orbit around the sun. Under this astronomical arrangement, a second is one-86,400th of our planet’s daily rotation. But because of tidal friction and other natural phenomena, that rotation is slowing down by about two-thousandths of a second a day. Since the 1950s, however, atomic clocks — which are based on the unwavering motions of cesium atoms — have made it possible to measure time far more accurately, to within a billionth of a second a day [The New York Times]. To keep the two measurement systems in alignment, the atomic clocks have to add an extra second about every 500 days.
In the western world, marriage between first cousins is labeled incest or inbreeding, and in the United States the practice is banned or restricted in 31 states. But a new essay argues that such laws are based on an outdated notion of the genetic risks involved in cousins marrying and reproducing. [T]hose laws “seem ill-advised” and “should be repealed,” a geneticist and medical historian write…. “Neither the scientific nor social assumptions that informed them are any longer defensible” [Scientific American].
First cousins share about an eighth of their genes, and are therefore more likely to receive two copies of some recessive gene that poses health problems. Scientists had assumed that the children of first cousins would therefore be more likely to be born with birth defects. But coauthor Hamish Spencer writes that the risk of congenital defects is about 2 per cent higher than average for babies born to first-cousin marriages – with the infant mortality about 4.4 per cent higher – which is on a par with the risk to babies born to women over 40. “Women over the age of 40 have a similar risk of having children with birth defects and no one is suggesting they should be prevented from reproducing,” said Professor Spencer [The Independent].
Paleontologists have taken another hard look at the fossilized remains of an arachnid that lived 386 million years ago, and have stripped away its title as the oldest known spider. The creature, Attercopus fimbriunguis, was originally believed to have the capacity to spin webs out of silk, but a reconsideration of the fragmented fossil has led researchers to conclude that Attercopus could make silk, but probably excreted it in sheets. These proto-spiders may have used sheets of silk to line burrows, wrap eggs or even to have sex [Nature News].
Previous studies had suggested that the Attercopus had a single spinneret, the appendage that spiders use to weave silk into webs. But lead researcher Paul Selden studied newly discovered fossil fragments and realized that those previous researchers were mistaken. The tiny hollow hairs that excrete spun silk, called spigots, are arranged in a double row on plates lining Attercopus’s belly, and what had been identified as a spinneret was actually a plate folded over. Without spinnerets, the creatures could not have precisely controlled the emerging silk. “It would have been much less manoeuvrable,” says Selden [Nature News].
The U.S. auto industry may be floundering in part because it failed to embrace fuel-efficient and alternative fuel cars, but U.S. companies can still position themselves to lead the way in the next phase of automobile manufacturing, a group of battery makers is arguing. Fourteen companies have announced that they’re teaming up and will seek $1 billion in federal aid to build a large-scale factory that produces lithium-ion batteries, which would be used in plug-in electric cars. Many experts believe battery technology and manufacturing capacity could become as strategically important as oil is today. Auto makers, including Corp. and Co., say they plan to roll out plug-in electric cars by 2010 [The Wall Street Journal].
The consortium, which calls itself the National Alliance for Advanced Transportation Battery Cell Manufacture, is modeled after a group formed in 1987 by computer-chip manufacturing companies that were struggling to compete with Japanese chip makers. The situation is similar now, experts say, as Asian companies dominate the battery market. “A small, fragmented (U.S.) battery industry will not long survive in the face of determined Asian competition,” Ralph Brodd, a consultant to battery manufacturers, said…. “(Other) countries understand that he who makes the batteries will one day make the cars,” he said [Reuters].
The small band of Homo sapiens that left Africa around 60,000 years ago, taking the first steps on a journey that would eventually disperse humans all around the world, may have been composed mostly of men. A new analysis of DNA variations in contemporary humans indicates that non-Africans descend from a population that contained far more males than females [New Scientist].
In the study, published in Nature Genetics [subscription required], researchers compared genetic samples from present-day African, European, and Asian populations. They were looking at the chromosomes that determine sex (two X chromosomes in women, one X and one Y chromosome in men), as well as the other 22 chromosome pairs, which are the same in both sexes. They examined the rate at which mutations randomly spread through the X chromosome over dozens or hundreds of generations as compared to the mutation rate in other, non-sex, chromosomes [AFP].
An experimental drug has shown promise in preventing emphysema in mice exposed to cigarette smoke, giving researchers new hope that they’ll soon find a way to combat one of the most stubborn, untreatable, and common killers of humans. Even though the study focuses on emphysema in mice, the researchers suggest the drug could work in people by delaying or preventing chronic obstructive pulmonary disease, which encompasses emphysema and chronic bronchitis and is the fourth most common cause of death in the United States [Science News].
The drug, called CDDO-imidazole, or CDDO-Im, works by activating a gene called Nrf2, explains study coauthor Shyam Biswal. In prior research, Biswal and colleagues found that Nrf2 works as a “master gene,” turning on genes involved in protecting the lungs from pollution and cigarette smoke. “The Nrf2 pathway is the major antioxidant and detoxifying response in the lungs. Therapies targeting this pathway need to be developed and tested in patients,” said Biswal [Reuters].
Honeybees might deserve the title of the farmer’s best friend: A new study shows that not only do the busy insects pollinate flowers and make honey, they also scare away agricultural pests that like to chomp on the leaves of crop plants. Said the study’s coauthors: “Our findings indicate for the first time that visiting honeybees provide plants with a totally unexpected advantage…. They not only transport pollen from flower to flower, but in addition also reduce plant destruction by herbivores” [BBC News].
The bees act as inadvertent protectors of plants, researchers say. Caterpillars are constantly on the lookout for wasps, one of their main predators, and have delicate sensory hairs on their bodies that detect the air currents caused by a wasp’s beating wings. “These sensory hairs are not fine-tuned,” said [study coauthor] Jurgen Tautz…. “Therefore, caterpillars cannot distinguish between hunting wasps and harmless bees.” If an insect which they cannot identify generates air vibrations the caterpillars stop moving or drop away from the plant [Telegraph].