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November 26, 2012

Plucked from obscurity: Microgromia, a living microbial spider web

Scientific American - Posted: November 26th, 2012, 11:35pm EST
Microgromia is a tiny amoeba with an organic shell who, much like a spider, lays down a sizeable spread of thread-like pseudopods (filopodia) lines with sticky extrusomes, waiting for the unfortunate bacterium or eukaryotic flagellate to stroll by. Unlike a spider, Microgromia does not need to wander off to apprehend trapped prey -- its web actively delivers the food straight to its mouth, seemingly digesting some of it along the way. While slower, quieter and much smaller than the truly-web-forming foraminifera, it can nevertheless handle some impressive flagellates on its own, relative to its size. You can usually find a ton of them by floating a coverslip atop some pond water samples, for a couple of days. The cell body itself appears to be quite determined to stay where it is, but you can watch the extrusomes and various tasty victims be slowly transported by the filopodia.The test (shell) has a bent neck that is characteristic of this genus. Bacteria get drawn through that neck and into their final resting place in an acidic digestive vacuole within the cell body proper. As one would expect of a freshwater species, Microgromia has a contractile vacuole complex that gradually expands as its components fill up and fuse, and then expels its contents somehow -- this appears to happen inside the test. The test itself generally starts out colourless and darkens to a brown with age, as a result of iron oxide (rust) accumulation. The nucleus is lined with strange granules, described as a chromidium in old literature. That term seems to have fallen out of use, but primarily because people stopped talking about it altogether. The identity of these granules is unclear, as there are no ultrastructural studies of these organisms to date, to my knowledge. a href=http://www.scientificamerican.com/blog/post.cfm?id=plucked-from-obscurity-microgromia-a-living-microbial-spider-web[More]/a

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Qatar Pressured to Cut Emissions as New Climate Talks Begin

Scientific American - Posted: November 26th, 2012, 5:40pm EST
pClimate change activists are pressing Qatar to pledge an emissions reduction target, money for vulnerable countries or some other significant contribution to the fight against global warming as it welcomes diplomats today to annual U.N. climate talks./p a href=http://www.scientificamerican.com/article.cfm?id=qatar-pressured-to-cut-emissions-new-climate-talks-begin[More]/a

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Dryland Farmers Work Wonders without Water in U.S. West

Scientific American - Posted: November 26th, 2012, 5:30pm EST
pSEATTLE ndash; In the long rain shadow of the Cascade Mountains, where dryland wheat farmers have eked out livings for more than a century, climate change is very much an issue of the present./p a href=http://www.scientificamerican.com/article.cfm?id=dryland-farmers-work-wonders-without-water-us-west[More]/a

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Brain Chemistry May Explain Bizarre Perpetual Sleepiness

Scientific American - Posted: November 26th, 2012, 4:20pm EST
pA new treatment may help people with a bizarre medical condition that makes them perpetually sleepy./p a href=http://www.scientificamerican.com/article.cfm?id=brain-chemistry-hypersomnia[More]/a

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Starving to be Social: The Odd Life of Dictyostelium Slime Molds

Scientific American - Posted: November 26th, 2012, 2:36pm EST
[caption id= align=aligncenter width=302 caption=Dictyostelium discoideum stalking up into a fruiting body. Earlier stages of growth are visible in the background.] [/caption]I like to think I have an active imagination, but Dictyostelium discoideum is an organism so bizarre I could not have dreamed it up on my own. a href=http://www.scientificamerican.com/blog/post.cfm?id=starving-to-be-social-the-odd-life-of-dictyostelium-slime-molds[More]/a

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Olfactory Overload Causes White Smell

Scientific American - Posted: November 26th, 2012, 1:25pm EST
pYour morning coffee. A baking pie. That turkey in the oven. There are some smells you just canrsquo;t get enough of. But mix them and other scents all together and you get, well, nothing much./p a href=http://www.scientificamerican.com/podcast/episode.cfm?id=olfactory-overload-causes-white-sme-12-11-26[More]/a

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Homo (Sans) Sapiens: Is Dumb and Dumber Our Evolutionary Destiny?

Scientific American - Posted: November 26th, 2012, 10:35am EST
James R. Flynns observation that IQ scores experienced dramatic gains from generation to generation throughout the 20th century has been cited so often, even in popular media, that it is becoming a cocktail party talking point. Next stop a New Yorker cartoon. (An article about Flynn and the Flynn effect has already been published in The New Yorker .)A recent report in Trends in Genetics ( part 1 and part 2 ) takes a bleaker view of our cognitive future--one that foresees the trend line proceeding inexorably downward. Gerald Crabtree, a biologist at Stanford University, has put forward a provocative hypothesis that our cushy modern existence--absent the ceaseless pressures of natural selection experienced during the Paleolithic--makes us susceptible to the slow creep of random genetic mutations in the the 2000 to 3000 genes needed to ensure that our intellectual and emotional makeup remains intact. The implications of this argument are that we as a species of the genus Homo are over many generations slowly losing our sapiens . a href=http://www.scientificamerican.com/blog/post.cfm?id=homo-sans-sapiens-is-dumb-and-dumber-our-evolutionary-destiny[More]/a

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Outbreaks of Foodborne Illnesses Are Becoming Harder to Detect

Scientific American - Posted: November 26th, 2012, 8:01am EST
pNew diagnostic tests for common foodborne pathogens such as Salmonella, Campylobacter, and Escherichia coli may hinder the ability of public health officials to detect multistate outbreaks. The problem is an inability to trace contamination to its source./p a href=http://www.scientificamerican.com/article.cfm?id=food-poisoning-outbreaks-become-harder-to-detect[More]/a

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Authenticating Cells Out of Curiosity, Not Fear

Scientific American - Posted: November 26th, 2012, 7:54am EST
[caption id=attachment_4879 align=alignright width=336 caption=Interior of an incubator showing cells growing in culture flasks, petri dishes, and microtiter plates.] [/caption]Cell lines are standard tools in biomedical research, and yet when it comes to their genetic identity, they are remarkably unstable. That volatility comes with their defining trait--immortality. Over time, cells accumulate mutations that may ultimately change the structure of chromosomes and alter cellular functions. a href=http://www.scientificamerican.com/blog/post.cfm?id=authenticating-cells-out-of-curiosity-not-fear[More]/a

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Auto-Immune: Symbiotes Could Be Deployed to Thwart Cyber Attacks

Scientific American - Posted: November 26th, 2012, 7:00am EST
pAnti-hacker defenses have long focused mainly on protecting personal computers and servers in homes and offices. However, as microchips grow smaller and more powerful, new targets for hackers are becoming widespread--embedded computers such as the electronics handling car engines, brakes and door locks ; the routers that form the Internet#39;s backbone; the machines running power plants , rail lines and prison cell doors ; and even implantable medical devices such as defibrillators and insulin pumps . Many of these embedded devices can now link with other computers, putting them equally at risk to intruders. Indeed, in October, Secretary of Defense Leon Panetta warned that the U.S. faced the threat of a quot;cyber Pearl Harborquot; if it failed to adequately protect these systems, echoing a warning CIA Director John Deutsch gave to Congress in 1996 about an electronic Pearl Harbor ( pdf )./p a href=http://www.scientificamerican.com/article.cfm?id=auto-immune-symbiotes-could-be-deployed-to-thwart-cyber-attacks[More]/a

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Stressing out really does make it worse

Scientific American - Posted: November 26th, 2012, 12:52am EST
Animals dont handle stress well. Im not talking about acute stressors, the predator charging at you through the brush, you run away and its over. We handle that stress very well indeed. But severe stress, losing a job, a divorce, a death in the family, these can really wear us down. Severe life stressors can not only impact your physical health, they also often occur before the onset of mental illness, particularly major depressive disorder. Depression takes many forms (lack of interest in activities, sleep changes, eating changes, severely depressed mood), but one of the most debilitating ones is the way that it impacts motivation. While some stressors (like, say, a deadline), might before have been a motivator, making you work to get it done, during depression, these stressors become insurmountable obstacles. Things you did before you couldnt possibly get done now. Youll never make the deadline. You cant run the race. Stress cant motivate you any more. What has changed? a href=http://www.scientificamerican.com/blog/post.cfm?id=stressing-out-really-does-make-it-worse[More]/a

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