PHOTO OF THE WEEK: Happy Polar Bear by Tilly Meijar
See many more extraordinarily beautiful or interesting and exciting, nature photos in the thread Beautiful Photographs of Animals and Nature. Doone is the main “culprit.” He always finds the best stuff!
TECHNOLOGY: How to see around corners
Light does not "bend", so we cannot see objects hidden around corners or behind walls. But scientists at the Massachusetts Institute of Technology in Cambridge have found a way to "see" hidden objects by exploiting the "echoes of light", in a similar way to sound echoes. They fired a pulse of laser light at a wall, and record the time at which the scattered light reaches a camera. Photons bounce off the wall onto the hidden object and back to the wall, scattering each time, and small fractions eventually reaches the camera, each at a slightly different time. Then they captured ultra-fast time-of-flight information (how long each photon takes to reach the camera). The camera is truly fast! It can record images every 2 picoseconds, the time it takes light to travel just 0.6 mm. This time resolution provides the key to revealing the hidden geometry. The technology is completed by a computer that compares images generated from different laser positions, and calculates the likely positions of the hidden object, in a similar way to the computational tomography that is used in CAT-scans. The technology is still in its infancy, because it takes several minutes to reveal the object, but in the future, it will be possible to reduce the time to <10 seconds.
ASTRONOMY: Could “Super Earths” Seed Microbial Life in their Solar Systems? Michel writes: this is a fascinating topic: interplanetary communications. It is a phenomenon actually happening in our local system - more than a few pounds of Martian rock hit the Earth every year - it opens up the possibility that life-building materials or indeed life itself could travel between neighboring planets. That would be typical of life, right? Filling every nook and cranny it can get to. Now scientists are beginning to consider how that neighborhood seeding would or would not be happening around our current exoplanet inventory. It would seem that not all planetary configurations allow for this process to occur.
MOLECULAR EVOLUTION: Resurrecting prehistoric proteins. Evolutionary biologist Joe Thornton came up with an excellent idea: to "resurrect" or rather recreate in the lab proteins from animals that have been extinct for many millions of years. His findings refute creationists' claims of "irreducible complexity" and show how different protein families evolved and gained new functions. Before becoming an evolutionary biologist, he was an environmental scientist working for Greenpeace. Because of the effect of pollutants on steroid hormone receptors, he started to study this receptor family. In vertebrates, there are 6 steroid hormone receptors; however, none had been found in arthropods or other invertebrates. Creationists claim these genes appeared from nowhere, hence, a creator. But in 2003, Thornton discovered an estrogen receptor-like gene from the mollusk Aplysia californica. What he did next was genius: starting with the genes for steroid hormone receptors from a bunch of vertebrates, and the newly discovered mollusk gene, he "walked backwards", down the evolutionary tree, and using computational biology, deduced the most likely sequence of the common ancestor of all these receptors. Such protein existed 600-800 million years ago, in the last common ancestor that mollusks and vertebrates shared. This ancestral gene was lost in the lineage leading to arthropods and nematodes. Thornton did not stop there: he built the gene in the lab, inserted it in cells, and studied its function. He showed that the ancient receptor responded to estrogen only, but not to other steroids, and that its function was lost somewhere along the Aplysia lineage. He has studied other receptors, and dissected the molecular steps that originated them. A few random mutations can explain it all. No need for a Creator.
TOXICOLOGY: Sudden death by Chinese killer mushroom. We have all heard about deadly foods, deadly mushrooms in particular, but it is rare to discover that a mushroom that people have been eating for a while is the responsible agent for sudden deaths of perfectly healthy people, with not too many obvious symptoms. The case of Yunnan sudden unexplained death syndrome has now been solved. It is caused by the mushroom Trogia venenata. The deaths followed a funny pattern, they occurred only in a narrow altitude band in the hills of Yunnan and neighboring provinces, in Southwest China, and only during the rainy summer season. The Chinese Center for Disease Control and Prevention had suspected the innocent looking white mushroom since 2009, and when they told people to stop eating it, the syndrome disappeared. But what was the deadly toxin and how did it cause the sudden death? It turns out that T. venenata produced 2 novel forms of unsaturated amino acids, and also γ-guanidinobutyric acid, a compound known to cause seizures in lab rats. Using mice to determine the cause of death, researchers found that the mushroom causes extreme hypoglycemia, in other words, blood sugar drops to such low levels, that cells cannot function anymore. At the molecular level, the toxins act in a manner similar to hypoglycin, the deadly compound found in unripe ackee fruit and seeds, which cause Jamaican vomiting sickness, with seizures and sometimes death. Hypoglycin blocks beta-oxidation, which is the production of ATP, the "currency unit" for energy transfer in cells, from fatty acids, that regenerates glucose. Since the heart is very dependent on beta-oxidation, this would explain the sudden deaths. The weird fungal compounds look structural similar to hypoglycin, hence, the victims do not simply become hypoglycemic and faint or seizure, because in addition to brain effects, their heart stops from blocked beta-oxidation. Case closed, although further toxicology tests will be carried out to study possible synergistic or dose effects, since some people who have eaten the mushroom have not died or even gotten ill.
NEUROSCIENCE: Insight Into a Shocking Therapy for Depression. Treating depression with electroconvulsive therapy (ECT) has been practiced since the 30s, although nowadays, this treatment is reserved only for the most severe cases of depression, since the therapy has pretty bad side effects such as loss of memory and difficulties forming new memories. A new article just published in PNAS explains why the therapy works in some cases. Depression can be the result of an overactive brain, and the electric shocks can dampen the activity of certain neural circuits. The hypothesis is that when the brain is overactive, there is too much internal communication and the patient's brain is thus focused mainly on itself, rather than on receiving inputs from the outside world. The overactive networks have been shown to converge in a brain region called the dorsal medial prefrontal cortex, in a location called the dorsal nexus. The PNAS paper shows that ECT dramatically decreased activity in the dorsal medial prefrontal cortex, in patients with depression, as assessed by fMRI. Since the dorsal nexus is a major node for attention, memory, and emotion, being the target of ECT makes sense because it explains the success of the therapy as well as the ugly side effects of memory impairment.
Science bits and news from other sites:
March 22: World Water Day. The 2012 theme is "Water and Food Security." Here is a fact everyone should know:
In order to feed the planet, we need water in sufficient quantity and adequate quality. We need to come up with ways to produce more food using less water, reduce food wastage and losses, and move towards more sustainable diets. Climate change is making it harder to reach the goal of ensuring adequate food and water for all. The UN Food and Agriculture Organization explains that climate change increases the variability of rainfall and the frequency of extreme weather events, and those two factors hinder food security. Changes in temperature and rainfall patterns may benefit agriculture in some areas but will harm it in others: FAO predicts that China could increase its cereal production by 100 million tons, but India will likely lose 30 million tons of cereal and Mozambique could lose 25% of its agricultural productive capacity. But there is some good news, at least for drinking water. In the past two decades, >2 billion people gained access to improved drinking water sources. There is still a long way to go: 783 million people still lack access to safe drinking water, and 40% of them are in sub-Saharan Africa. It will also take work to ensure that the people who've gained access to improved drinking water are able to maintain it. This World Water Day is a reminder that we still have a long way to go before everyone has the water, and food needed to live healthy lives.
Objects weigh less at Earth's equator because the planet's spin and shape lessen gravity's pull here versus at the poles. Satellite accelerometers have confirmed this, but a digital scale manufacturer decided to test things the old-fashioned way, using a garden gnome (always the same gnome), and the same precise scale. See this link here for details and also if you would like to participate in this worldwide experiment. When placed on a scale at the South Pole, the so called Kern gnome weighed 309.82 grams, versus 307.86 grams at the equator, a difference of 0.6%. The gnome's next stop will be the CERN laboratory near Geneva, Switzerland, according to Kern Precision Scales, the manufacturer of the digital scale and the sponsor of the gnome's travels.
Rare "Emerald Cut" Galaxy Found. Most galaxies are either disk-shaped with spiral arms (like our own Milky Way), ellipsoid, or blob-like. But astronomers have now discovered an oddity: an unusual symmetrical rectangular galaxy. It was named LEDA 074886, and it is a dwarf galaxy 70 million light-years away in the constellation Eridanus, the River. The galaxy was spotted using the Subaru Telescope in Hawaii. At first astronomers thought there was a mistake with the image, but the galaxy is actually shaped like a short cylinder, sort of like a case of CDs, see from the side. The emerald-cut dwarf was missed up until now because it is located along the edge of a massive elliptical galaxy, NGC 1407. The boxy dwarf galaxy has 50 X fewer stars that the Milky Way. Astronomers speculate that it was formed by a merger of two spiral galaxies that had their axes pointed in opposite directions. Computer simulations have shown that when two ellipsoid galaxies merge, they would form similar boxy shapes, but nobody had seen such extremely rectangular galaxy before. LEDA 074886 has a geometric outline and an inner disk where stars are being born. The formation of LEDA 074886 will be modeled on a supercomputer later this year; this may help determine for how long the galaxy is likely to keep its odd shape. The well defined corners may disappear over the next billion years.
Were Some Neanderthals Brown-Eyed Girls? Neanderthals are often depicted as having a very northern European look, blue or green eyes, red or blond hair. But new DNA analysis suggests that two of the most famous Neanderthals, at least from the point of view of their DNA, three females from Croatia, actually had brown-eyed and were brunettes with tan-colored skin. Their DNA was the basis of the almost complete Neanderthal genome, which was published in 2010. The new DNA analysis is not without controversy, since many researchers have hypothesized that Neanderthals mostly inhabited northern latitudes, they must have evolved paler skin in order to absorb sufficient doses of vitamin D. However, not all Neanderthals inhibited northern latitudes, and there may have variation in skin color among them, just as there are variations among Homo sapiens. For this new analysis, a team of Brazilian geneticists focused their attention on ~40 well-studied stretches of DNA that help determine eye and skin pigmentation in humans, for a total of 124 single nucleotide polymorphisms. They validated their methodology to deduce phenotype from genotype by looking at the DNA from 25 Homo sapiens, 11 of them identifiable (like Jim Watson, Craig Venter, etc, for whom the phenotype is known). To deduce eye and skin color from DNA sequences is not so simple to do because eye and skin color are complex traits controlled by multiple genes. The researchers came up with an algorithm to score additive gene effects. For example, the female Neanderthal known as Vi33.26, had 7 genes for brown eyes, 1 for "not-brown" eyes, 3 for blue eyes, and 4 for "not-blue” eyes." This means a positive balance in favor of brown and a negative balance for blue, so Vi33.26's eyes were probably brown. According to this method, all 3 Neandertals had a dark complexion and brown eyes, two were likely to have brown hair, and one was likely to have been red-haired. Some evolutionary biologists are saying that the problem with their additive methodology is that different genes have different levels of impact. Carles Lalueza-Fox of Spain's Institute of Evolutionary Biology in Barcelona argues that some pigmentation genes have such a powerful effect that they override the combined contributions of many weaker genes. The lighter skin color seen in Europeans, for instance, is due almost entirely to a single gene, he says, and that there are some genes that have a very strong effect on physical appearance. But regardless of methodology, both Lalueza-Fox and anthropologist John Hawks thinks Neanderthals probably had a range of skin and eye color according to where they lived, for example, Neanderthals who lived in Israel likely had darker skin than their European counterparts.
New clues to the cause of male pattern baldness. A new biological pathway previously unknown to have a role in male pattern hair loss, has been identified, raising hope for future treatments for hair loss. Although male pattern baldness, or androgenetic alopecia (AGA), affects ~80% of men at some point in their lives, only one predisposing factor, a variant of the testorone receptor gene, has been identified, but it is found in only a minority of men with AGA. Present treatments were discovered by sheer luck. Finasteride (Propecia) was originally prescribed for prostate enlargement, and minoxidil (Rogaine) for hypertension. How they work is still not clear. The new research identified the lipid-containing compound, prostaglandin D2 (PGD2) as inhibiting hair growth. At team of dermatologists from the University of Pennsylvania, examined gene expression in balding and non-balding scalp tissue from five men with androgenetic alopecia. They found that PGD2 was more abundant in the balding scalp tissue, as was prostaglandin D2 synthase, which produces PGD2. The researchers also found that, PGD2 expression peaks during the hair-growth cycle stage in which the follicle begins regressing, in mice. Cultured human follicles, and mice treated with PGD2 also showed inhibition of hair growth. The finding fits with previous work that had role for other prostaglandins in hair growth. For example, the eyelash-growth enhancer latanoprost is an analogue of prostaglandin F2-alpha3, and prostaglandin E2 has been shown to promote hair growth in mice. This suggests that different prostaglandins may balance each other, with some promoting growth and some, such as PDG2, inhibiting it. There are some drugs out there known to indirectly inhibit the function of PDG2, and these are going to be investigated for their ability to stop hair loss or even promote hair growth. In 2011, the same team showed that hair-follicle stem cells are still intact in bald scalp, even though their proliferatio is inhibited. If PGD2 is the stem cell inhibitor, blocking it may allow stem cells to multiply and give rise to new follicles. At this point, it is still speculative.