Scientists have identified the “master” stem cell that gives rise to the three types of heart cells, possibly opening the door for new methods of pharmaceutical research and heart therapies, such as growing a patch to repair cardiac tissue damaged by heart disease, according to a study published in Nature.
The research illuminates a crucial facet of how heart tissue develops and shows why past studies to repair heart tissue with stem cells had poor results: the cells used were not the heart tissue progenitors that lead author Kenneth Chien and his team identified. The researchers then purified the cells, cloned them and tracked their journey from single stem cell to the three major lineages of heart cells — smooth muscle, cardiomyocyte [or striated] muscle and endothelial cells [U.S. News and World Report], which line the inside of the heart. For years, scientists have studied the development of the heart in animals like the zebra fish, but this finding will allow researchers to closely examine the genesis of human cardiac tissue in unprecedented detail.
Don’t be alarmed, but on a remote island in Scotland the sheep are shrinking.
Instead of gradually increasing in size as expected due to evolution, the average weight of the wild sheep has decreased as average temperatures heat up. The discovery shows that a species’ response to global warming can be unpredictable, and can be based on multiple factors. According to a study published in Science, warmer and wetter winters have made it easier for smaller sheep to survive the hard months and go on to bear offspring, thus passing these “small” genes onto the next generation of sheep.
Since 1985, the average weight of the wild Soay sheep living on the island of Hirta has decreased by about 5 percent. Due to global warming, the winters on the Scottish isles are becoming becoming shorter and milder. That makes food more abundant and allows some of the smaller, more vulnerable and younger sheep to survive. Then they go on to have offspring that tend to be small themselves — and have a better chance of survival because of the increasingly mild winters. “The environmental and evolutionary processes are intertwined. There’s still natural selection, but it’s not leaving as big a signature as it used to. There’s still a disadvantage to being small, but not as much” [Time], says lead researcher Tim Coulson.
Computers powered by frickin’ laser beams just came a step closer. Light-based, or photonic, computers would theoretically be much faster and smaller than the electronic computers we use today, but researchers have had a hard time putting theory into action. Now, a new study has shown that two laser beams can be harnassed to turn a single molecule into a transistor. However, the specialized conditions necessary for the trick to work mean that computer stores won’t have photonic sections anytime soon.
Conventional computers are based on transistors, which allow one electrode to control the current moving through the device and are combined to form logic gates and processors. The new component achieves the same thing, but for laser beams, not electric currents. A green laser beam is used to control the power of an orange laser beam passing through the device [New Scientist]. In the study, published in Nature, the green beam could make the orange beam either weak or strong, which is analagous to an electronic transistor turning a current on or off.
Although ethical debates about the use of embryonic stem cells continue to rage, stem cell technology is beginning to make its way into the medical marketplace. Yesterday, General Electric division GE Healthcare announced that it’s teaming up with the biotechnology company Geron in a venture that will use embryonic stem cells to develop products that could give drug developers an early warning of whether new medicines are toxic [Reuters].
The agreement marks the first time that a company of GE’s stature and size has announced a business venture involving the controversial field of embryonic stem cells. That could reflect a more tolerant climate for the technology in the wake of the Obama administration’s recent relaxation of restrictions on embryonic stem-cell research [The Wall Street Journal]. Supporters of embryonic stem cell research say the work will lead to a host of treatments for cancer and other diseases, while opponents believe that the destruction of any human embryo is unacceptable.
The question of how salamanders regenerate their legs when amputated is an ancient one that dates back to the days of Aristotle. Now scientists have come one step closer to solving the mystery. Contrary to what researchers previously believed, when a salamander’s legs are removed the cells near the amputation site revert to adult stem cells, but do not become pluripotent, or capable of developing into any body part. That explains why a salamander who loses a tail doesn’t regrow a leg in its place.
In the study, published in Nature, scientists explain that when a salamander’s limb is amputated, the muscle, bone, and skin cells at the amputation site change into a clump of adult stem cells called a blastema. Before this experiment, researchers had hypothesized that these undifferentiated blastema cells — which all look identical — are pluripotent and thus able to form many different cells types. But it was not clear how the original cells from adult tissue were reprogrammed, or how the blastema cells went on to form the correct tissue types [Nature News].
Many animals depend on stealth to catch prey, but a small tentacled water snake resorts to downright trickery. That’s what a Vanderbilt University scientist found when he analyzed the way the snake captures fish, according to a study published in the Proceedings of the National Academy of Sciences.
The snake, which is native to Southeast Asia, takes advantage of a well-known reflex that fish possess. The mechanism occurs when a fish’s ear senses changes in water pressure due to movement nearby, which is all it takes to initiate the fish’s escape response, called the C-start — one of the most well studied neural circuits in vertebrates. Two large nerve cells, known as Mauthner cells, run along either side of the fish’s body and detect water disturbances. The cell closest to the signal will fire action potentials that stimulate trunk muscles on the opposite side of the body while simultaneously inhibiting the muscles on the near side. As a result, the fish turns away from the disturbance and flees. This whole process takes less than a tenth of a second [The Scientist]. The reflex causes the fish’s body to form a “C” as it turns away from the source of the underwater vibration—but in this case, that leads the fish right into the snake’s jaws.
In a rare victory for freedom of information in China, the government has abruptly reversed course on its mandate that Internet filtering software be installed on every computer sold in China after July 1.
Yesterday, the Ministry of Industry and Information Technology announced that mandatory installation of the software, called Green Dam Youth Escort, would be delayed indefinitely. The software caused a torrent of protests from both Chinese computer users and global computer makers…. China has said the software is designed to filter out pornography and violence to protect minors, but many experts say it can also block any other content that the authorities deem subversive [The New York Times].
While some experts suggested that the Chinese government might be delaying the program’s roll-out simply to give computer makers more time to test the software and comply with the policy, others believe that the government was forced to bow to the pressure from outraged citizens. “This shows that social pressure can’t be ignored,” said Zhou Ze, a Beijing lawyer who challenged the legality of the plan. “They tried to control public opinion to back the plan by creating a fuss about pornography, but that failed, and they will have learnt to be more careful next time” [Reuters]. Analyst Edward Yu of Beijing says that while protests from foreign computer companies probably influenced the government’s decision, “we think public opinion played an even more important role” [AP].
The duck-billed dinosaurs have been giving up their secrets lately. Just yesterday researchers revealed new details of how hadrosaurs chewed their food, using a set of teeth that look like a “cranial cuisinart.” Today, paleontologists have put the hadrosaur’s skin on display, thanks to a “mummified” creature that shows the shape of its soft tissue and cell-like structures.
Such a discovery was possible because the dinosaur’s skin fossilized before bacteria had a chance to eat up the tissue. It is “absolutely amazing to be able to identify organic molecules from soft tissue that belonged to a beast that died over 66 million years ago…. This is the closest you’re going to get to patting the animal” [National Geographic News], says lead researcher Phillip Manning.
Chemotherapy destroys cancer cells, but it also kills healthy cells. In addition, cancer cells left behind after treatment can develop resistance to therapy, rendering follow-up treatment ineffective. But a new type of cancer treatment that uses cellular “Trojan horses” to slip into cancer cells could remedy that. In a study published in Nature Biotechnology, Australian researchers describe a method that has successfully treated aggressive and resistant tumors in mice and dogs.
The technique uses a rising technology known as RNA interference, or RNAi, which was the subject of research for the 2006 Nobel Prize in medicine recipients. This technology prevents the cell from manufacturing proteins by muting the genes responsible for their production, and relies on “mini-cells” to silence these genes. In the new study, these mini-cells were produced by bacteria and then coated with antibodies the cancer cells recognized, which allowed the mini-cells to target and slip inside of cancer cells like a Trojan horse.
The researchers use a two-step attack against the cancer cells. The first wave of mini-cells releases molecules that switch off the production of proteins that make the cancer cell resistant to chemotherapy. A second wave of EDV [mini] cells is then accepted by the cancer cell and releases chemotherapy drugs, killing the cancer cell. “The beauty is that our EDVs operate like ‘Trojan Horses’ They arrive at the gates of the affected cells and are always allowed in” [Reuters], says study coauthor Jennifer MacDiarmid.
Human beings are increasingly making their homes on the coasts of continents, but this demographic shift is taking a toll on a sensitive coastal ecosystem that is often overlooked: seagrass meadows. A new analysis of seagrass abundance around the world found that 27 percent of these meadows have disappeared since 1879, and the rate of loss is accelerating. The study’s authors write: “Seagrass loss rates are comparable to those reported for mangroves, coral reefs and tropical rainforests, and place seagrass meadows among the most threatened ecosystems on earth….. Our report of mounting seagrass losses reveals a major global environmental crisis in coastal ecosystems, for which seagrasses are sentinels of change” [Nature News].
Endangered species expert Susanne Livingstone notes that despite these losses seagrass rarely makes it into the public consciousness. “It’s probably because they’re not as sexy [as corals], they’re not as attractive,” she says. “They’re just as ecologically important if not more so” [Nature News]. Seagrass meadows provide grazing for a variety of marine animals, including the green turtle and the manatee-like dugong. The coastal areas also serve as nurseries for fish; both coral reefs and commercial fisheries would feel the impact if seagrass meadows vanish.
In the first confirmed case of drug-resistant swine flu worldwide, a Danish patient developed resistance to Tamiflu, the antiviral treatment used for flu prevention and treatment. The patient recovered and did not appear to have passed the resistant strain to others. While a drug-resistant virus could make it harder to treat and prevent the spread of the flu, experts maintain that the isolated case is not a cause for alarm, and say Tamiflu is still effective against the swine flu.
A spokesman for Tamiflu manufacturer Roche says the Danish patient developed drug-resistant swine flu while taking the drug as a preventative to avoid the contraction of swine flu…. He was probably already infected with the virus, and resistance to the drug emerged because he was given the lower preventative dose [The Wall Street Journal]. This type of resistance is known as drug-induced resistance, as opposed to naturally occurring resistance, in which a strain itself mutates to become unresponsive to a medication.
The U.S. Centers for Disease Control and Prevention continues to recommend Tamiflu to treat the flu, along with another flu drug, Relenza. The World Health Organization also is expected to keep supporting the use of Tamiflu. Tamiflu-resistant strains of the seasonal flu have been found in Japan, which has used more than half the world’s supply of the drug each year. But those strains were weak and did not spread. A Tamiflu-resistant strain of the H5N1 bird flu was also isolated from a Vietnamese patient being treated with low-dose Tamiflu in 2005, but it also died out [The New York Times].
The union between the native California tiger salamander and the non-native barred tiger salamander, which was brought in huge numbers from Texas beginning 60 years ago by California bait dealers [The New York Times], has produced an alarming hybrid offspring. A new study of the hybrid’s behavior in artificial ponds serves as a reminder that invasive species can alter ecosystems in unexpected ways: in this case, by getting too cozy with the natives of central California.
The new hybrid “superpredator” grows larger than either of its parent species, and its bigger mouth enables it to suck up a wide variety of amphibian prey, said lead study author Maureen Ryan…. Mostly on the menu are smaller pond species, such as the Pacific chorus frog and the California newt—both of which were “dramatically reduced” in population by the hybrid in the experiments [National Geographic News].
The duck-billed dinosaurs more properly known as hadrosaurs were the most prolific vegetarians of the late Cretaceous period, and researchers think their unusual mouth mechanics may have played a role in their evolutionary success. A new study of the hadrosaur Edmontosaurus examined the animal’s fossilized teeth in unprecedented detail. Using an electron scanning microscope, researchers were able to examine minute scratches on individual dino teeth made by daily wear and tear 65 million to 68 million years ago to test competing theories about how the creatures may have munched [Scientific American].
The mouth of a hadrosaur has been compared to a “cranial Cuisinart,” with hundreds of teeth lined up in rows to chop up the tough plants of the late Cretaceous. But the dinosaurs didn’t have the complex jaw joint that mammals have, leaving scientists to puzzle over exactly how hadrosaurs did all that chewing [MSNBC]. The study, published in the Proceedings of the National Academy of Sciences, found scratches indicating that the movements of a hadrosaur’s teeth was a complicated matter, involving sideways and front to back motions as well as the traditional up and down chomp.
In a 219-212 vote, the House of Representatives passed on Friday a climate bill designed to decrease U.S. dependence on oil and create “green” jobs. It’s now up to the Senate to pass or veto the American Clean Energy and Security Act, which also proposes a cap-and-trade system to impose historic limits on U.S. greenhouse gas emissions.
The bill has been tweaked since it was approved in May by the House Energy and Commerce Committee, and it remains unclear how much progress the Senate will make on the bill. In it, U.S. emissions of carbon dioxide and other greenhouse gases would be reduced 17 percent by 2020 from 2005 levels. That is less ambitious than the 20 percent initially sought, but slightly more aggressive than the approximately 15 percent Obama proposed. The legislation sets further pollution reduction goals — 42 percent by 2030 and 83 percent by 2050, with the latter just slightly higher than Obama suggested [Reuters]. The bill also speeds up the administration of $346 million in stimulus funds for the development and implementation of energy efficient technology.
Global warming is expected to cause such alarming climate disruptions that talk of hurricanes and heat waves can overshadow another drastic process at work: Burning fossil fuels and otherwise producing excess carbon dioxide makes oceans and other bodies of water more acidic, as the water absorbs the gas. This acidification can change a fish’s physiology in ways that were previously unpredicted and could affect the fish’s survival, according to a study in Science.
Scientists raised groups of white sea bass in water of varying concentrations of carbon dioxide. They found that the fish in the most highly acidified water had the largest rock-shaped ear bones, known in biology parlance at otoliths. That contradicts what the researchers had hypothesized: The ear structure in fish, known as an otolith, is made up of minerals. Scientists knew that increasing carbon dioxide in the oceans — absorbed from the atmosphere — is making the sea more acidic, which can dissolve and weaken shells. They wondered if it also would reduce the size of the otoliths [Los Angeles Times]. Instead, the ear bones of fish growing in the tank with six times as much carbon dioxide than normal were 15 to 17 percent larger than normal. An water with a CO2 concentration about 3.5 times higher than current levels yielded fish with otoliths that were 7 to 9 percent larger than those raised in water with today’s carbon dioxide levels. That’s the CO2 level predicted by the year 2100.
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Scientists have identified the “master” stem cell that gives rise to the three types of heart cells, possibly opening the door for new methods of pharmaceutical research and heart therapies, such as growing a patch to repair cardiac tissue damaged by heart disease, according to a study published in Nature.
Don’t be alarmed, but on a remote island in Scotland the sheep are shrinking.
Computers powered by frickin’ laser beams just came a step closer. Light-based, or photonic, computers would theoretically be much faster and smaller than the electronic 
Although ethical debates about the use of 
The question of how 
In a rare victory for freedom of information in 
The duck-billed dinosaurs have been giving up their secrets lately. Just yesterday researchers revealed new details of how 
Chemotherapy destroys 
Human beings are increasingly making their homes on the coasts of continents, but this demographic shift is taking a toll on a sensitive coastal 
In the first confirmed case of drug-resistant 
The union between the native California tiger salamander and the non-native barred tiger salamander, which was brought in huge numbers from Texas beginning 60 years ago by California bait dealers [
The duck-billed 
In a 219-212 vote, the House of Representatives passed on Friday a 
Global warming is expected to cause such alarming climate disruptions that talk of hurricanes and heat waves can overshadow another drastic process at work: Burning fossil fuels and otherwise producing 
