The epidermis of a mouse tail imaged with confocal microscopy after immunostaining. The "bulge" region of the hair follicle (red) harbors the hair follicle stem cells. Blue marks the DNA in the nucleus, and the basal cells of the epidermis are labeled green via an antibody to integrin α6.More great pictures from skin images here.
And for a great gallery of photos from Popular Science magazine, check out the ten top new species of 2012, including a sneezing money, a night-blooming orchid, and this gorgeous, strikingly blue new species of tarantula from Brazil.
FEATURED VIDEO: Paralyzed rats learn to walk again
A team of Swiss scientists has managed to teach paralyzed rats with spinal cord injuries how to walk again. They put the rats on a robotic harness that forced them to try to use their paralyzed hind legs (otherwise they would just drag themselves by walking on the front paws), they gave them a chemical cocktail to stimulate nerve growth, and then an electrical stimulus to the spinal chord, to rouse the neurons. The rats needed to consciously want to move their legs, so they used chocolate as a stimulus. This willpower-based training resulted in the formation of new nerve fibers. The rats could walk after 2 weeks of training, and after 6 weeks, they could walk on their hind legs for extended periods of time, recovering basically 100% of their hind leg function. Based on these astonishing results, human clinical trials are set to start in 2 years.
Amazing pulsars. Pulsars are extraordinary astrophysical objects: they are special neutron stars, made of a kind of matter beyond intuitive understanding. Imagine a ball 10 miles in diameter, a teaspoon of which weighs a billion tons with a "B" spinning at hundreds of revolutions per second. They concentrate so much gravitational and magnetic forces that they can heat up interstellar gasses light years away to multimillion degree Celsius. And now they became even more amazing. The Large Area Telescope (LAT), at the Fermi Gamma-ray Space Telescope, that collects information on high-energy gamma rays from space, just discovered a previously unknown waveform, consisting of a gamma-ray peak before and after each radio peak . This suggests that the radio part of the beam may originate at two distinct points above the object’s surface, something not previously explained by current models of pulsar geometry. The image represents the complex nebula surrounding the young pulsar PSR B1509-58. The pulsar itself is the bright white spot at the center, blue and purple colors indicate X-rays emitted by the pulsar. The thin jet to the lower left is a beam of particles shooting out from the pulsar's south pole at > 130 million mph. The green cloud near the top of the image is due to the incredibly hot gas (many millions of degrees). Original story here.
The talk of the town in the past couple of weeks has been the SpaceX’s Dragon capsule being docked at the International Space Station (ISS) on May 22. It is the first commercial vehicle to dock into the ISS. Space X is a privately owned California-based spacecraft company funded by Elon Musk (PayPal). As a commercial venture, Musk intends to dramatically lower the cost of space travel and to fly people to ISS soon. NASA’s controversial shift toward reliance on commercial spacecraft appears validated by the successful Dragon mission. The Dragon is an un-crewed modular spacecraft, contracted by NASA to deliver cargo to the ISS. Its first demo flight was in 2010. It took 3 days for the Dragon to reach the ISS from Cape Canaveral. The ISS used a 58-foot robotic arm to grab the spacecraft and dock it to its Harmony node, as both spacecraft flew 250 miles above northwest Australia at a speed of 17,500 mph. Station crew then opened the Dragon’s hatch and unloaded its cargo, then loaded it up with 1400 pounds of cargo to deliver back to Earth as a test. The Dragon successfully splashed down into the Pacific Ocean yesterday, Thursday May 31, off the coast of Mexico. A fleet of boats will transport the capsule by barge to Los Angeles, then by truck to the SpaceX rocket factory in Texas for unloading and inspection. The Dragon capsule is the only cargo craft capable of returning equipment to Earth from ISS, unlike the Russian, European and Japanese ones that burn up on re-entry. Space X has won a $1.6 billion contract to fly >10 resupply missions for NASA, using Dragon. The first of these missions is scheduled for September of this year. The commercial, private entrepreneurship side of this story has been much touted, but let’s not forget that US taxpayers have contributed around $500 million to the development of these cargo vehicles.
Rare neurons linked to empathy and self-awareness found in macaque .... As Monty Python used to say: “And now for something completely different!” Uniquely large, spindle-shaped neurons in the anterior insular cortex (AIC) that have the super-badass name of von Economo neurons (sounds like a Marvel comics villain name) are thought to have a key role in self-awareness and social cognition, including empathy, in humans. This type of neuron was previously thought to exist only in the brains of humans and great apes. But a team from the Max Planck Institute in Germany has now found von Economo neurons (VEN) in macaques, in the agranular anterior insula of the monkey’s brain. The shape, size, and distribution suggest that it is an anatomical homolog of the human VEN. The macaque could now be used as a laboratory model to study the primal connections and physiology of this important type of neuron. This could be important to study some neuropsychiatric disorders, since damage to the insula leads to apathy, and to the inability to recognize what feelings are being experienced by other people or even by the affected person. The insula is also affected in autism and in frontotemporal dementia. The AIC in particular is where humans consciously experience the so-called subjective emotions (e.g. love, hate, self-confidence, embarrassment, jealousy). Interestingly, though macaques fail the mirror self-recognition test, the new data provides compelling evidence that monkeys possess at least a primitive form of von Economo neurons. Perhaps self-awareness as measured by the mirror test is the wrong test to evaluate self-awareness in non-human animals. Certainly macaques are a social species, they are capable of experiencing empathy and of altruistic behaviors. Surprise, surprise: the foundations of our moral sense do not come from gods or religion, but from evolution and the biology we share with non-human animals. The original story can be found here.
“Occupy the Neolithic” or how we ended up inequalities. How did we end up with gross inequalities in human societies if even macaques have empathy neurons? Not that this would surprise too many people, but inequality has existed in human societies going back at least 7,000 years. The scientific data comes from a new study of skeletons from prehistoric farming communities across Europe. Many researchers think inequality, or at least hereditary inequality, started with the advent of agriculture, but archaeological data from 10,000 years ago in the Near East (supposedly the birthplace and time of agriculture) has given mixed results with respect to clear evidence for social stratification. But in the European Neolithic, specifically the Linearbandkeramik (LBK) farming culture, which started in today’s Hungary ~7500 years ago, archaeologists started to notice the tell tale signs of social stratification. Only certain males were buried with adzes, for example. A team of British archaeologists started studying the tooth enamel in > 300 skeletons from 7 LBK burial sites in the Czech Republic, Slovakia, Austria, and France. Why tooth enamel? The ratio of two strontium isotopes in teeth can be used to deduce the type of soil and geological formations a person lived on, particularly as a child, because strontium comes from the food we eat and water we consume. The ratio of strontium isotopes in the tooth enamel can be used to track population movements. This isotope ratio also can distinguish fertile lowland sediments, the kind favored by farmers, from less fertile hills made of granite or sandstone. The results, just published in the Proceedings of the National Academy of Sciences, show that men who were buried with adzes were more likely to have grown up on fertile loess soils than men who were buried without adzes. This suggests a higher social status for the guys buried with adzes. There were 62 skeletons with adzes and all but one showed an isotope ration corresponding to growing up on food grown on fertile soil. Interestingly, the variation in strontium ratios for females was significantly greater than for males, suggesting that a greater number of females than males had grown up in non-fertile areas. The archaeologists believe some males had greater access to fertile soils than others, probably because they were the sons of farmers who had inherited access to the best land. The female data suggests that the LBK societies were "patrilocal," meaning that males stayed in one place and females moved in from other areas to get mates Genetic studies of early European farmers also suggest a male-dominated descent system. One of the team members stated that these conclusions are very solid, and that the differences seen between men and women in this Neolithic society, are consistent with the pattern seen in more recent farming societies, even up to the present day.
Dog domestication may have helped humans thrive while Neanderthals .... Why did Homo sapiens thrive while Neanderthal populations declined where the two overlap? H. sapiens sites show a higher density of tools and a larger prey size overall, so the H. sapiens population grew tenfold over the 10,000-year overlap period. There are many hypothesis to explain this outcome, from better hunting weapons to climate change. And now there is another good hypothesis: we dominated because we domesticated dogs. First, dogs were domesticated during the period when both modern humans and Neanderthals overlapped in Europe. Second, all the early dog fossils are from modern-human sites (in the photo, Neolithic site in Italy in which a woman and a dog were buried together). And dogs were important and valued, because they were sometimes buried with care: at least one dog was buried with a bone in its mouth. Canine teeth were used as jewelry. And the large number of perforated dog braincases suggests a ritual significance. Paleolithic dogs were certainly not lap dogs; they were mostly the size of a modern German shepherd dog. They could have used as beasts of burden. Some modern societies still do this. All but one of the six Paleolithic dog sites had large quantities of mammoth bone which, which must have been lugged from the kill site to where the group was living. Dogs may have carried the meat, humans would have saved energy, and the kill was divided so both humans and dogs gained from the partnership. Dogs could also have contributed more directly to human hunting success. In contemporary Finnish moose hunts, the use of Norwegian elkhounds or Finnish spitzes resulted in an increase of 56 % in the weight of meat hunted, compared to hunters without dogs. The dogs could have been very useful in finding game, as well. There are tons of data from modern populations using hunting dogs that show a better success in finding and killing prey than groups who do not use dogs. If Neandertals did not have dogs and anatomically modern humans did, it could have given us humans a definitive edge. The article contains interesting speculation on the appearance of white sclera (the white of our eyes), which the great apes do not have but we do, with the ability to follow the gaze not only of other humans, but also the ability that domestic dogs have of following our own gaze. We look into our dogs eyes to communicate with them and know what they feeling, and our dogs do the samePerhaps we co-evolved to communicate with each other and this communication with dogs gave our species the upper hand over Neanderthals. I wonder if Neanderthal DNA would indicate if Neanderthals had white sclera or if their eyes were more like those of apes.
If you've learned a new term today, it makes me happy. Rorqual whales (Family Balaenopteridae) are baleen (toothless) whales that have pleated throat grooves that expand tremendously when the whales feed, allowing them to take huge gulps of water that they then force through their short baleen (baleen is basically a keratin filter system) to trap the organisms that were in the engulfed water. Examples are the blue whale, humpback whale, Minke whale, Sei whale. "Rorqual" is Norwegian for furrow. In this BBC video you can see a Sei whale feeding on a fish school. One of the greatest mysteries of nature is how these massive animals manage to consume enough tiny fish and other marine organisms to not only survive, but grow to their massive size. Their feeding style, known as lunge feeding, is a feat of synchronization and power. When a rorqual finds a dense patch of krill or fish, it accelerates with an open mouth. The amount of water that flows into the whale's mouth can almost double its weight! The throat pleats expand and the normally sleek giant looks temporarily like a bloated monster, until it expels the water out forcefully. Rorqual whales can lung feed for hours at a time. The skull and mandibles of rorquals are very specialized: they have unique jaw joints made from dense elastic matrices of fiber and cartilage, which allow the jaw to be opened at 90 degrees. The lower jaw has a flexible joint in the middle, which allows the two sides to rotate. The tongue can be turned inside out, creating more space for water. But how does the whale coordinate all these movements? Researchers the Smithsonian Institution describe a sensory organ, highly vascular and highly enervated, embedded in the lower jaw joint of several rorqual whale species. The organ is evolutionarily derived from ancient tooth sockets and it contains papillae that appear to work as mechanoreceptors, in other words, an organ to sense stretching and pressure. The organ is an evolutionary novelty for rorqual whales, because it was not found in any other group of baleen whales. Link to original Nature article can be found here. Abstract is free; the full article is behind a pay-wall.
Fire-loving beetles sense infrared radiation from many miles away. And while we are on the subject of specialized sensory organs, how about an infrared detector in beetles? This was really news to me: there are animals that instead of fleeing fires, they chase them: fire-chaser beetles (genus Melanophila) love blazes. Why? They have evolved to lay their eggs only in freshly burnt trees, which have lost their natural defenses in the fire. Since the beetles can’t reproduce without fires, these insects have been known to travel even 30 miles while chasing fires. They sense infrared radiation threw a pair of pits below their middle pair of legs. Each pit contains ~ 70 dome-shaped sensors, filled with a liquid that expands when it absorbs infrared radiation. The stretching stimulates sensory cells and that’s why the beetles know there is fire ahead. These detectors are so sensitive, that beetles can detect it from tens of miles away. German scientists have recently calculated that the beetles’ pits can sense a minimum of 0.13 milliwatts/m2 of changing heat flux, making them as sensitive as the radio telescopes used in astronomy. Go to the link above to read Ed Yong’s superbly entertaining article on the fire-chasing beetles, including an anecdote that involved swarms of beetles harassing and biting the spectators at UC Berkeley football games: everybody smoked backed them, and the numerous lit cigarettes were driving the beetles crazy. The original PLoS One article measuring the heat-sensing threshold of the beetles’ infrared detector can be found here.
The Scientific Search for the Essence of a Tasty Tomato. From animals we go to the plant world. My favorite kingdom, when it comes to food. I think that we can all agree that supermarket tomatoes are tasteless. What happened to that fantastic tomato flavor of my childhood, to that burst of sweetness in your mouth when you eat a really good tomato salad? I thought it was simply my pet peeve, but it turns out that scientists are hard at work trying to figure out what compounds are responsible for tomato flavor. Tomatoes are complicated when compared to a banana. A banana has one single volatile compound that one can immediately identify as the essence of banana flavor and smell. But tomatoes have over 400 volatile compounds. Scientists had several tasting panels evaluate samples of 158 heirloom tomato varieties, and they statistically correlated the presence of specific volatile compounds with great flavor in a tomato. They have narrowed down the list to around twenty compounds responsible for the sweetness and the flavor of tomatoes. The results have just been published in Current Biology. The article includes a study of the genetic basis for tomato flavor. Interestingly, aroma volatile compounds are crucial to our perception of sweetness in a tomato, independent of sugar levels. The researchers identified which compounds were relevant for consumer preference by knocking down the production of C6 volatiles, abundant compounds thought to be important for flavor. But these compounds were actually irrelevant to consumer preference. Very low-abundance compounds, such as geranial, 2-methylbutanal and 3-methyl-1-butanol were of tremendous importance in terms of flavor and sweetness. The idea is to understand in detail which genes are responsible for the production of these low abundance volatile compounds, in order to breed back the flavor into the tomatoes. Incidentally, the big, red, gorgeous looking tomatoes that are absolutely tasteless ended up that way because growers favored high yields, disease tolerance, aesthetic value and shelf life. Until, recently, commercial growers did not care at all about flavor. So in this artificial evolution, the selective pressure for flavor was lost while other characteristics were favored. It seems crazy that we now depend on sophisticated tomato genomics and genetic engineering to restore flavor to tomatoes, when that delicious flavor had been selected by nature before, and probably by our ancestors who cared about flavor, not just cheap production. Luckily for us, the tomato genome has just been fully sequenced this week, and the task of tomato geneticists chasing the key to a flavorful fruit is now easier.
Scientists take the fun out of marijuana. And while some scientists are striving to put the flavor back into tomatoes, others have succeeding in taking the high out of pot. Israeli scientists have cultivated a cannabis plant that should work for medical purposes, but will not make smokers stoned. According to the Israeli newspaper Maariv daily, the new plant looks, smells and tastes the same, but does not induce the high that comes from the famous THC (tetrahydrocannabinol). The firm that developed the new cannabis variety is called Tikkun Olam; the new pot was tried on patients who thought they were given placebo because smoking it did not make them high. The strategy of the scientists at Tikkun Olam managed to neutralize the effect of the THC and to increase the effect of cannabidiol, which has been shown to help diabetics and to ease various psychiatric disorders. The new marijuana does not give people the munchies either, which I thought was a beneficial side effect because it helped people with loss of appetite (from cancer treatment, for example), eat better. Before we get all excited (or upset at these killjoy scientists), clinical trials will have to be run to determine if the high-less pot has the same beneficial effects as the normal garden variety. Marijuana has been approved for medical use for about 6,000 Israelis suffering from various illnesses.