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Females Choose Biological Fitness Over Other Traits In Mating Game

Females Choose Biological Fitness Over Other Traits In Mating Game | Amazing Science |
A new study from the National Institute for Mathematical and Biological Synthesis finds that a female's mating decisions are largely based on traits that reflect fitness or those that help males perform well under the local ecological conditions.

Via Maria Nunzia @Varvera
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Painting by numbers - how natural pigmentation variation of species is generated

Painting by numbers - how natural pigmentation variation of species is generated | Amazing Science |

Individuals of a particular species generally differ from one another by a variety of features, including pigmentation. We are clearly most adept at recognizing members of our own species, although dog and cat owners will be ready to confirm that their pets look unique. Differences within species relate to characteristics such as size and shape but also to color: it is not only humans that show a wide range of skin pigmentation. Nevertheless, the cause of the variation in skin color in animals has remained largely unknown. Recent work in the group of Christian Schlötterer at the University of Veterinary Medicine, Vienna sheds light on the topic.


The skin color of humans ranges from pale pinkish-white to very dark brown and relates largely to the amount of melanin produced by specialized cells in the body. The synthesis of melanin is under the influence of a bewildering array of genes, each of which naturally occurs in a variety of different forms or alleles, thus accounting for the wide variety of skin colors found in our species.


Color also differs, albeit sometimes more subtly, in many other animals. For example, the color of the abdomen in the fruit fly Drosophila melanogaster varies considerably. Because flies are much more amenable to genetic study than humans, we know a good deal about pigmentation in Drosophila. At least nine genes are directly involved in the synthesis of pigment, together with a number of others that indirectly affect the pattern of pigmentation. Nevertheless, it is not clear whether changes in these genes account for the variation in the pigmentation of natural populations of flies or whether differences in other genes might somehow be responsible.


The issue has been tackled by Héloïse Bastide and Andrea Betancourt at the Institute of Population Genetics of the University of Veterinary Medicine, Vienna. The researchers examined 8,000 female flies, split into 5 groups, and chose 100 of the lightest and 100 of the darkest from each group for genetic comparison. Each group of light and dark flies was pooled and its DNA sequenced, resulting in a catalogue of the genetic differences between light and dark flies at over three million positions in the fly genome. Sophisticated statistical methods were used to compare the differences between the two groups, leading to the discovery of 17 sites where variation (SNPs), seemed to be associated with the extent of female abdominal pigmentation.


Gratifyingly, the SNPs were found to lie in or close to genes known to be involved in pigment synthesis, in particular the tan and bric-à-brac1 genes. Most of the SNPs were not in the coding sequence of these genes but instead in nearby sequences that had previously been shown to regulate their activity.


In other words, the variation in the colour of female flies is not a result of changes to the genes that produce pigments but stems instead from subtle alterations in the regulation of the pigmentation genes. Bastide and Betancourt are naturally excited by their findings. As they say, “Our work has taught us a lot about how pigment production can be controlled and at least some of our conclusions may apply to other species as well. But even more importantly, our experiments show that pooling and sequencing samples can represent an effective and low-cost method to examine the basis of natural variation in populations.”

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Fast-sinking jellyfish drag carbon to the seafloor

Fast-sinking jellyfish drag carbon to the seafloor | Amazing Science |
When jellyfish die they sink to the ocean floor faster than other marine organisms, allowing the oceans to absorb carbon dioxide, new research shows.



The study, published in Limnology and Oceanography, is the first ever to look at how quickly some gelatinous life in the oceans sinks.


This sinking biomass is an important part of the process by which carbon is exported from the ocean surface to the seafloor. Understanding how quickly dead organisms sink means scientists can make better estimates of how much carbon the oceans can absorb in the future.


Around 25 per cent of the carbon dioxide emitted from human activities dissolves into the oceans, where billions of tiny plankton start to transform some of it into organic carbon through photosynthesis.


As larger organisms, like jellyfish and pelagic tunicates – small transparent filter-feeders – eat these plankton, the carbon passes through the food chain until the animals die and sink to the sea floor.


As they sink the carbon is dragged down through the water column, away from the surface waters, where it is either ingested by scavengers, or stored in the deep water. This means more CO2 can be absorbed into the oceans at the surface.


Previous studies had shown that plankton and marine snow – the organic detritus that falls out of the water column – are the main sources of carbon transport to the seafloor. But this study showed jellyfish sink much faster and so may be able to transport even more carbon away from the surface.

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Sequencing reveals complex history of amphibian-killing fungus

Sequencing reveals complex history of amphibian-killing fungus | Amazing Science |

One of the biggest threats facing amphibian species is the disease chytridiomycosis, which is caused by a fungus known as Batrachochytrium dendrobatidis (Bd). An understanding of the evolutionary history of microbial pathogens, like Bd, is critical to predicting disease outbreaks and causes of shifts in virulence. The sudden appearance of Bd worldwide suggests a recent introduction into the affected areas, likely facilitated by the international movement of amphibians. A new paper published yesterday in PNAS reveals that the evolutionary history of Bd significantly predates recent outbreaks, and is much deeper and more complex than previously thought. Using whole-genome sequencing from a global panel of Bd isolates, researchers suggest that Bd likely originated somewhere between 10,000 and 40,000 years ago, but could be as old as 100,000 years.

The decline in amphibian populations due to Bd is concerning since they play an essential role in food webs, and have broad aesthetic and medicinal value. Bd infects hundreds of species of amphibians and kills by disrupting the integrity of their skin. Earlier, but limited, studies found little genetic differentiation in Bd, with no clear geographic signal. This would be consistent with a recent, rapid spread of a novel disease agent. The new study in PNAS, is an extensive collaboration including researchers from the US, Mexico, Argentina, Columbia and Australia. It makes use of whole-genome sequencing to show that the geographic lineage of Bd is much more widespread and diverse than had been assumed.

If Bd were largely endemic, researchers would expect deep phylogenetic structure in the Bd tree corresponding to locality or host association. If instead, Bd were entirely novel, they would expect a shallow and comb-like tree topology. To infer the relationships in the Bd tree, the researchers used 29 isolates sequenced to depth of 24x, and 101,000 SNPs. What they found was a history that was both novel and endemic. Generally, isolates that shared a common geographic or host association did not cluster within clades. Similarly, many closely related isolates did not share a common geography.


The researchers applied a molecular clock to estimate the age of key nodes within the phylogenetic tree. The dates provided are dependent on an assumed rate of evolution under a strict clock (0.0081 substitutions per site per million years) and a tree prior derived from the constant population-size coalescent. It should be noted that these kinds of model assumptions have received some valid criticisms in past and should only serve as estimates. The researchers also note that although sexual reproduction has never been observed in Bd, sexual recombination and hybridization have been proposed as important mechanisms in its evolutionary history.


For the future, the researchers hope to focus on some of the less sampled parts of the world, and include additional host species. They also hope to link phylogenetic variation with functional variation. Evidence from the lab has suggested that some more recent isolates may be more deadly than the early-diverging isolates, particularly those from South Africa. Because virulence is an emergent property of the host-microbe-environment interaction, comparisons among isolates will be difficult. Controlled experiments and consistent assays will be needed to piece together parts of the larger Bd puzzle.

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Can Life Evolve from Wires and Plastic?

Can Life Evolve from Wires and Plastic? | Amazing Science |

In a laboratory tucked away in a corner of the Cornell University campus, Hod Lipson’s robots are evolving. He has already produced a self-aware robot that is able to gather information about itself as it learns to walk.


Hod Lipson reports: "We wrote a trivial 10-line algorithm, ran it on big gaming simulator, put it in a big computer and waited a week. In the beginning we got piles of junk. Then we got beautiful machines. Crazy shapes. Eventually a motor connected to a wire, which caused the motor to vibrate. Then a vibrating piece of junk moved infinitely better than any other… eventually we got machines that crawl. The evolutionary algorithm came up with a design, blueprints that worked for the robot."

The computer-bound creature transferred from the virtual domain to our world by way of a 3D printer. And then it took its first steps. Was this arrangement of rods and wires the machine-world’s equivalent of the primordial cell? Not quite: Lipson’s robot still couldn’t operate without human intervention. ‘We had to snap in the battery,’ he told me, ‘but it was the first time evolution produced physical robots. Eventually, I want to print the wires, the batteries, everything. Then evolution will have so much freedom. Evolution will not be constrained.’


Not many people would call creatures bred of plastic, wires and metal beautiful. Yet to see them toddle deliberately across the laboratory floor, or bend and snap as they pick up blocks and build replicas of themselves, brings to mind the beauty of evolution and animated life.


One could imagine Lipson’s electronic menagerie lining the shelves at Toys R Us, if not the CIA, but they have a deeper purpose. Lipson hopes to illuminate evolution itself. Just recently, his team provided some insight into modularity—the curious phenomenon whereby biological systems are composed of discrete functional units.


Though inherently newsworthy, the fruits of the Creative Machines Lab are just small steps along the road towards new life. Lipson, however, maintains that some of his robots are alive in a rudimentary sense. ‘There is nothing more black or white than alive or dead,’ he said, ‘but beneath the surface it’s not simple. There is a lot of grey area in between.’


The robots of the Creative Machines Lab might fulfill many criteria for life, but they are not completely autonomous—not yet. They still require human handouts for replication and power. These, though, are just stumbling blocks, conditions that could be resolved some day soon—perhaps by way of a 3D printer, a ready supply of raw materials, and a human hand to flip the switch just the once.


According to Lipson, an evolvable system is ‘the ultimate artificial intelligence, the most hands-off AI there is, which means a double edge. All you feed it is power and computing power. It’s both scary and promising.’ What if the solution to some of our present problems requires the evolution of artificial intelligence beyond anything we can design ourselves? Could an evolvable program help to predict the emergence of new flu viruses? Could it create more efficient machines? And once a truly autonomous, evolvable robot emerges, how long before its descendants make a pilgrimage to Lipson’s lab, where their ancestor first emerged from a primordial soup of wires and plastic to take its first steps on Earth?

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How Do Organs Know When They Have Reached the Right Size?

How Do Organs Know When They Have Reached the Right Size? | Amazing Science |

Development is, literally, the journey of a life time, and it is a trip still as mysterious as it is remarkable. Despite new methods to probe how an animal or plant forms from a single cell, biologists have much to learn about the unimaginably complex process. To identify some of the field’s persistent riddles, Senior Editors Beverly Purnell and Stella Hurtley and the news staff of Science have consulted with developmental biologists on our Board of Reviewing Editors and elsewhere. The mysteries offered here are a humbling reminder that our knowledge of development remains to a great extent embryonic.


Developmental biologists have found dozens of proteins and genes that play a role in the growth of plants and animals, such as imaginal discs and Hippo and morphogenetic proteins, but not what determines organ size.


A variety of experiments have shown that both the size of imaginal discs and the organs they form are very tightly controlled. When researchers transplant the wing imaginal disc from an early fly larva to a later one or vice versa, the wing still reaches normal size despite having different growing times. If researchers kill a portion of the imaginal disc cells with radiation or other techniques, the insect can boost cell division and still form a normal-size adult. If a fly receives just a fragment of a disc as a transplant, the animal won’t move to the next stage of development until the disc has reached the correct size—pausing overall development to allow the disc to catch up. The transplanted disc “will know what size it should be,” says developmental biologist Savraj Grewal of the University of Calgary in Canada.


Many researchers suspect that a developing organ somehow senses the mechanical forces on its growing and dividing cells. One theory is that relative crowding and stretching of cells helps determine whether a cell continues to divide or stops.


The size of an organ depends not only on how many cells it has, but also how big those cells are. Some developing organs—plant leaves, for example, and fruit fly wings—can compensate when fewer cells are available by making the individual cells larger. How a leaf knows when to expand its cells is also unclear, says Hirokazu Tsukaya, a developmental biologist at the University of Tokyo who was among the first to characterize the phenomenon in leaves. He and his team have evidence that some sort of cell-to-cell communication drives the process. Here, too, the evidence suggests that a plant doesn’t count cells but can somehow assess the overall size of a leaf, says plant biologist Beth Krizek of the University of South Carolina in Columbia. “But the mechanism of how that works is another mystery.”


The size of tissues, and ultimately an overall organism, also clearly depends on signals from the environment, which researchers call extrinsic factors. Those size control systems are connected to, but different from, the intrinsic systems that help ensure an organism is correctly proportioned. In plants, growth can be especially sensitive to such outside factors, Krizek notes, because they can’t move. Plants growing in shade, for example, concentrate on stem growth—to reach the sun—instead of leaf development. In animals, the amount of nutrition available can strongly influence the final size of some organs. One dramatic instance is the horn on a rhinoceros beetle. The horn is a sexually selected trait; males with bigger horns get access to more females. Recent studies have shown that the size of the horn is particularly sensitive to insulin signaling, which is related to the beetle’s nutrition. That, in turn, signals the animal’s overall fitness (Science, 27 July 2012, p. 408).


The problem of size control is still a fundamental one for developmental biologists, says Peter Lawrence of the University of Cambridge in the United Kingdom. Together with shape, size “is the material that evolution largely works on.” But the field is still mostly in the dark. Despite hundreds of papers on what happens when the Hippo signaling pathway is interrupted, Lawrence notes, what scientists really need to understand is what it does when it is working properly. “That is not something we know.”


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Nuclear bomb tests reveal definitive evidence of brain regeneration in humans

Nuclear bomb tests reveal definitive evidence of brain regeneration in humans | Amazing Science |

Nuclear bomb tests carried out during the cold war have had an unexpected benefit. A radioactive carbon isotope expelled by the blasts has been used to date the age of adult human brain cells, providing the first definitive evidence that we generate new brain cells throughout our lives. The study also provides the first model of the dynamics of the process, showing that the regeneration of neurons does not drop off with age as sharply as expected.


In mammals, most types of brain cell are created at or soon after birth and are never renewed. But studies in rodents and monkeys have shown that in two regions new neurons continue to be created even in adulthood – the hippocampus, which is involved in learning and the formation of new memories, and the olfactory bulb, which processes smell.


However, there has been some controversy over whether the same is true for humans. Fifteen years ago a study found evidence for such neurogenesis in adults up to the age of 72 (Nature Medicine,, but the research relied on a chemical called bromodeoxyuridine (BrdU) to label neurons. BrdU was used at the time to track the spread of tumours in people with cancer, but it was banned shortly after and so the study was never repeated, leading some researchers to question the results.


The new study settles the debate. "The existence of adult hippocampal neurogenesis in humans is not arguable this time," says Sandrine Thuret at King's College London, who was not involved in the work.


Instead of chemical labelling, Jonas Frisén at the Karolinska Institute in Stockholm, Sweden, and colleagues used a by-product of the above-ground nuclear bomb tests carried out by the US, UK and Soviet Union between 1945 and 1963. As a result of these detonations, atmospheric levels of the radioactive isotope carbon-14 increased dramatically during this period. It has decreased steadily since.


Carbon-14 enters the food chain and eventually finds its way into our cells, which integrate carbon-14 atoms into their DNA when a parent cell splits into two new daughter cells. The amount of carbon-14 in the atmosphere is therefore mirrored in the cells at the time they are born.


By analysing brain tissue using mass spectrometry equipment, the team was able to measure the number of carbon-14 atoms trapped in different populations of cells in different brain regions.


They could then compare this figure to known data for atmospheric levels of carbon-14 to date the birth of a cell in different people to within about a year. The level of carbon-14 is higher in older cells grown closer to the peak of nuclear bomb testing than in cells born more recently.


Frisén's team previously used this method to show that humans are the only known mammal in which neurogenesis does not occur in the adult olfactory bulb, since the cells in this brain region were the same age.

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15 New Bird Species from the Amazonian jungle

15 New Bird Species from the Amazonian jungle | Amazing Science |

The Amazon rainforest, a well-known epicenter of biodiversity, has offered up another trove of riches. The treasure takes the form of 15 newly described bird species. Some are tiny. One has a long, curved bill. Another is super fluffy. All live in the southern Amazon, most of them in an area known as the “arc of deforestation.”


The Arapaçu-de-bico-torto, which loosely translates to crooked-beaked woodcreeper. This bird most closely resembles a Curve-Billed Scythebill (Campylorhamphus procurvoides), said Tom Schulenberg, an expert in neotropical birds and Peruvian species, from the Cornell Lab of Ornithology.

It’s been 140 years since as many new Brazilian bird species were described at one time. In 1871, 40 new species were described by Austrian August von Pelzeln in Zur Ornithologie Brasiliens.


Discovered mostly within the last five years, in southern swaths of forest, many of the birds live near rivers. Eleven can only be found in Brazil; four of the species have also been seen in Peru and Bolivia. Most are Passeriformes, belonging to an order that includes ravens, sparrows, and finches.


They were spotted on various expeditions that included ornithologist Luis Silveira, of the University of São Paulo, and his students, as well as collaborators from three additional institutions. Together, they noticed that these strange new birds didn’t quite fit in.


“Describing new species is not a trivial task,” Silveira said. Many sang different songs, or had different genetic sequences than previously known birds. “We considered a bird as a new species when at least two of the three criteria — plumage, voice, and genetics — were consistently different from some previously known and closely related, already described species.”


Silveira and his colleagues will describe the species in a special volume of the Handbook of Birds of the World, which will be published in early summer. Here, we have photos of seven new species; others have only been illustrated.


Vloasis's curator insight, June 6, 2013 8:32 AM

What sheds a pall over these discoveries (the largest group in 140 years), is the fact that deforestation helped reveal them.

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3.5 billion years ago, meteorites provided reactive phosphorus essential for creating the earliest life on Earth

3.5 billion years ago, meteorites provided reactive phosphorus essential for creating the earliest life on Earth | Amazing Science |

Most astrobiologists believe that life in some form is likely to exist away from Earth. But new research demonstrates that life as we know it on Earth might never have come to exist at all if not for a key element delivered to the planet by meteorites billions of years ago.


Scientists at the University of Washington and the University of South Florida found that during the Hadean and Archean eons – the first two of the four principal eons of the Earth’s earliest history – the heavy bombardment by meteorites provided reactive phosphorus essential for creating the earliest life on Earth.


When released in water, that reactive phosphorus could be incorporated into prebiotic molecules, and the researchers documented its presence in early Archean limestone, showing it was abundant some 3.5 billion years ago.


“The importance of this finding is that it provides the missing ingredient in the origin-of-life recipe: a form of phosphorus that can be readily incorporated into essential biological molecules like nucleic acids and cell-membrane lipids,” said Roger Buick, a UW professor of Earth and space sciences.


The scientists concluded that the meteorites delivered phosphorus in minerals that are not now seen on the surface of the Earth, and these minerals corroded in water to release phosphite, a form of phosphorus seen only on the early Earth.


“Meteorite phosphorus may have been a fuel that provided the energy and phosphorus necessary for the onset of life,” said Pasek. “If this meteoritic phosphorus is added to simple organic compounds, it can generate phosphorus biomolecules identical to those seen in life today.”


He said the research provides a plausible answer for why we don’t see new life forms on Earth today: The conditions under which life arose billions of years ago are no longer present.


“The present research shows that this is indeed the case: Phosphorus chemistry on the early Earth was substantially different billions of years ago than it is today,” he said.


The findings are based on examination of samples from Australia, Zimbabwe, West Virginia, Wyoming and Florida. The presence of phosphite was detected only in the oldest samples, from surface materials and drill cores from the early Archean in Australia.

Xuan Phan's curator insight, August 15, 9:27 PM

This is an interesting news!

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Invasive Snail Protects Its Young With Odd Poison

Invasive Snail Protects Its Young With Odd Poison | Amazing Science |

Many kinds of snails are invading ecosystems all over the world, but the apple snail (Pomacea canaliculata) has a unique advantage: Almost no predators will eat its eggs. That's because the bright pink objects (see picture) are filled with a neurotoxin that scares off every predator except for red fire ants. Now, researchers have discovered that the neurotoxin, called PcPV2, is quite unusual for animals. First, it's a so-called AB toxin, and its two subunits share homology with membrane attack complex/perforin (MACPF)-like toxins and tachylectin-like lectins, a previously unknown structure that resembles plant Type-2 ribosome-inactivating proteins and bacterial botulinum toxins. The protomer has therefore a novel AB toxin combination of a MACPF-like chain linked by disulfide bonds to a lectin-like chain, indicating a delivery system for the former. And second, the apple snail creates it in an unprecedented way, combining a pair of molecules that resemble those belonging to the immune system of other animals. As for the embryonic snails, cocooned in a toxic egg, they are equipped with enzymes that can degrade the neurotoxin and use it for nutrition during development, the researchers reported. The acquisition of this unique neurotoxic/antinutritive/storage protein may confer the eggs a survival advantage, opening new perspectives in the study of the evolution of animal defensive strategies.

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Dog And Human Genomes Evolved Together

Dog And Human Genomes Evolved Together | Amazing Science |
A new study finds that genes for diet, behavior, and disease in dogs and humans have evolved together.


Researchers from the University of Chicago and several international institutions found that several groups of genes in humans and dogs—including those related to diet and digestion, neurological processes, and disease—have been evolving in parallel for thousands of years.

This parallel evolution was likely driven by the shared environments of humans and dogs, wrote the authors in a study published May 14, 2013 in the journal Nature Communications.


"As domestication is often associated with large increases in population density and crowded living conditions, these 'unfavorable' environments might be the selective pressure that drove the rewiring of both species," the authors surmise.


For example, living in crowded conditions with humans may have conferred an advantage on less aggressive dogs, leading to more submissive canines and eventually to the pets whose puppy-dog eyes gaze at us with unconditional affection.


The study authors suggest that dogs were domesticated 32,000 years ago; that's much earlier than current estimates, which place domestication at around 15,000 to 16,000 years ago.


"Thirty-two thousand is a little bit old," said Bob Wayne, an evolutionary biologist at the University of California, Los Angeles. Although he does acknowledge that the timing of a split between wolves and dogs has varied widely—ranging between 6,000 and 120,000 years ago.

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Pigeons intelligent enough to learn to use a computerized touchscreen to solve puzzles

Pigeons are fairly intelligent creatures, and their ability to be trained or used as messengers suggests they have a modicum of memory and learning capability. But how smart are they exactly? According to research published in Animal Cognition, pigeons are capable of solving a pattern-based puzzle to earn a food reward. Better yet, they can do so even when the puzzle displayed on a touchscreen—a pretty abstract concept for a bird, wouldn't you say?


The experiment by researchers at the University of Iowa consisted of digital versions of string tasks, which are commonly used in cognition studies. The premise is simple: a study subject is given a pair of strings, with a food reward visibly attached to one of them. If the subject pulls the right string, it wins the reward. Simple, right? Even marmosetscan do it.

But in this case, there was a wrinkle. The study pigeons didn't just have to look at two strings, realize one had food on the end of it, understand that pulling the string would bring the food, and act on it. They had to do so in a purely digital fashion.


As you can see in the video above, two strings were drawn on screen, each with a picture of a food dish—one full, one empty—attached to the end of it. Poking at a button at the bottom of the drawn strings reels them in; it looks like it took about a dozen or so pokes to pull in the "string" fully. If the full dish was pulled in, a real food reward was given.


"The pigeons proved that they could indeed learn this task with a variety of different string configurations—even those that involved crossed strings, the most difficult of all configurations to learn with real strings," lead author Edward Wasserman said in a release.


Success rates for pigeons across varying experimental configurations ranged between 74 and 90 percent—pretty high, if you ask me. And really, break it down like you had no idea what a touchscreen was: You see pictures of food, colored lines, and a couple little button things. You can poke or peck aimlessly, but only when you hit the buttons does the screen react. Eventually, you realize that hitting the right button brings the virtual food closer, which eventually results in a real reward.


It's pretty fascinating that pigeons are capable of learning to complete such a task. At the same time, the study shows the sheer intuitiveness of touchscreen interfaces. As opposed to the blinking cursors of yore, touchscreens offer a more physical interface that's easier to interact with.

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The tiny insect (Zorotypus impolitus) with the massive 3 mm long single sperm

The tiny insect (Zorotypus impolitus) with the massive 3 mm long single sperm | Amazing Science |

A Malaysian ground louse has a unique mating habit that may illuminate how sex evolved: the males attach an unusual packet of sperm to the females' bodies.


Everything about Z. impolitus mating is strange. The female starts the process, approaching the male and stroking him with her antennae. If the male wants to mate, he moves behind her and performs a simple dance: he walks forwards and backwards, lowers his head and vibrates his antennae.


The climax of the process is when the male slips underneath the female for a few seconds and attaches a spermatophore to the female's abdomen: a tiny package with a large surprise. "It [the sperm package] is the smallest we have seen in all insects," he says. Whereas other species make spermatophores up to 2 millimetres across, those of Z. impolitus are just 0.1 millimetres across.


When Dallai dissected some of these spermatophores, however, he found that each one contained a single sperm about 3 millimetres long – about as long as the female. This seems strange. Males generally want to maximise their chances of fertilising the female's eggs, so why produce only one, giant sperm?


Dallai thinks it may be a way of outcompeting other males. "The sperm is so large, it can fill the space in the female's [genital tract]," he says. That plugs it up, so no other male can mate with her. Also, by using only one sperm at a time, the male ensures he gives each female just enough to fertilize her, while leaving him plenty to fertilize other females.

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Researchers Try to Explain How Perfectly Round Pearls Form

Researchers Try to Explain How Perfectly Round Pearls Form | Amazing Science |

Pearls develop as nacre and other liquids accumulate around grains of sand or other foreign objects inside certain oysters and other shellfish.

“But how do pearls grow into such perfect spheres?”


Dr Julyan Cartwright from the CSIC – Universidad de Granada in Spain and colleagues point out that the most flawless and highly prized pearls have perhaps the most perfectly spherical, or ball-like, shape among all the objects in nature that are visible without a microscope. “The answer may be relatively simple — with developing pearls having a saw-toothed, or ratchet-like, surface,” Dr Cartwright and his colleagues said.

That texture generates forces that make the pearl turn inside the oyster’s tissues in response to movements in the environment.


“The result is a spherical build-up of nacre and other textures. Rotating pearls are a perhaps unique example of a natural ratchet,” the scientists concluded.

Via David Simpson
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Earth is surrounded by a 'bubble' of live bacteria - at 33 000 feet

Earth is surrounded by a 'bubble' of live bacteria - at 33 000 feet | Amazing Science |

Earth’s upper atmosphere—below freezing, nearly without oxygen, flooded by UV radiation—is no place to live. But last winter, scientists from the Georgia Institute of Technology discovered that billions of bacteria actually thrive up there. Expecting only a smattering of microorganisms, the researchers flew six miles above Earth’s surface in a NASA jet plane. There, they pumped outside air through a filter to collect particles. Back on the ground, they tallied the organisms, and the count was staggering: 20 percent of what they had assumed to be just dust or other particles was alive. Earth, it seems, is surrounded by a bubble of bacteria.

Scientists don’t yet know what the bacteria are doing up there, but they may be essential to how the atmosphere functions, says Kostas Konstantinidis, an environmental microbiologist on the Georgia Tech team. For example, they could be responsible for recycling nutrients in the atmosphere, like they do on Earth. And similar to other particles, they could influence weather patterns by helping clouds form. However, they also may be transmitting diseases from one side of the globe to the other. The researchers found E. coli in their samples (which they think hurricanes lifted from cities), and they plan to investigate whether plagues are raining down on us. If we can find out more about the role of bacteria in the atmosphere, says Ann Womack, a microbial ecologist at the University of Oregon, scientists could even fight climate change by engineering the bacteria to break down greenhouse gases into other, less harmful compounds.

Ed Rybicki's comment, June 25, 2013 3:39 AM
Hey, it's a microbial world - literally! From way above our heads, to way below our feet.
Dmitry Alexeev's curator insight, June 27, 2013 1:21 AM

we are everywhere)

Dmitry Alexeev's curator insight, July 28, 2013 7:31 AM

we'll have that one in our book as well


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Ocean Plastics Host Surprising Variety of Microbial Species

Ocean Plastics Host Surprising Variety of Microbial Species | Amazing Science |

A surprising suite of microbial species colonizes plastic waste floating in the ocean, according to a new study. These microbes could speed the plastic’s breakdown but might also cause their own ecological problems, the researchers say (Environ. Sci. Technol. 2013, DOI: 10.1021/es401288x).


Plastic waste from consumer products often finds its way into the oceans in a range of sizes, from microscopic particles to large chunks. This accumulation of plastic worries environmental scientists. For example, fish and marine mammals can mistake the plastic pieces for food and ingest the debris, or toxic chemicals can leach from the plastics.


But much still remains unknown about the ecological impacts of these materials. So a group of Massachusetts researchers, led by Linda A. Amaral-Zettler at the Marine Biological Laboratory and Tracy J. Mincer at Woods Hole Oceanographic Institution, decided to study the microbial communities found on plastics to explore how the organisms affect marine environments.


The team analyzed plastic samples they collected during two research cruises to the North Atlantic Subtropical Gyre, a stretch of ocean roughly midway between the eastern coast of North America and Africa. They used a scanning electron microscope, among other techniques, to study the bacteria living on the particles. “What we found really blew us across the room,” says Mincer, a microbial ecologist: They couldn’t say for sure, but the bacteria appeared to burrow pits into the plastic, which had never been observed before. The team didn’t expect such behavior, because they thought nutrient levels in that region wouldn’t support bacteria digesting hydrocarbons in this way.


The group suspects this may at least partially explain a surprising aspect of plastic waste found in previous studies in this region of the Atlantic. Even though the amount of plastic waste entering the ocean is probably increasing, researchers at Sea Education Association, a nonprofit group that studies the ocean environment, have not found an increase in plastics in the sea (Science 2010, DOI: 10.1126/science.1192321).


Mincer says one possible explanation is that bacteria eat into the polymers, weakening the pieces enough to cause them to break down more quickly and eventually sink to the sea floor. Supporting this hypothesis, some of the plastic-burrowing bacteria are closely related to species known to consume other types of hydrocarbons, such as oil.

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First fluorescent protein identified in a vertebrate

First fluorescent protein identified in a vertebrate | Amazing Science |

The Japanese freshwater eel (Anguilla japonica) has more to offer biologists than a tasty sushi snack. Its muscle fibres produce the first fluorescent protein identified in a vertebrate, researchers report in Cell.


Fluorescent proteins are as standard a tool for cell biologists as wrenches are for mechanics. They do not produce light themselves, but glow when illuminated. The 2008 Nobel Prize in Chemistry was awarded for the discovery and development of such molecules, which are used to tag proteins or to track how genes are expressed. The molecules have been engineered to produce light in a variety of hues and brightnesses, but those discovered until now in nature all came from non-vertebrates, mainly microbes, jellyfish, and corals.


The first clues to the eel protein’s existence came in 2009 when Seiichi Hayashi and Yoshifumi Toda, food chemists studying nutrients in eel at Kagoshima University in Japan, were tracking lipid transport into oily eel tissue and reported that eel muscle fluoresced naturally glowing green when a blue light is shone on it. They then isolated a few fragments of the protein responsible. This intrigued Atsushi Miyawaki, a molecular biologist at the RIKEN Brain Science Institute in Wako, Japan, who has identified and engineered new properties into fluorescent proteins from jellyfish and corals.


In the latest work, Miyawaki and his colleagues have identified the gene that codes for the molecule, and have named the new protein UnaG, after unagi, the Japanese word for freshwater eel that is familiar to sushi lovers worldwide.


“I don't think anyone would have thought that eels would have such a bright fluorescent protein,” says Robert Campbell, a protein engineer at the University of Alberta in Edmonton, Canada. And UnaG is in a class of its own, he says. “It's totally different” from other fluorescent proteins. “There's not anything you can point to that's the same.”


For example, instead of producing light with a 'chromophore' that is part of the protein sequence, as the classical Green Fluorescent Protein (GFP) does, UnaG fluoresces when it binds a naturally occurring small molecule called bilirubin, a breakdown product of haemoglobin used in hospital tests for decades to assess liver function and diagnose diseases such as jaundice.


UnaG is also unusual because, unlike GFP, it fluoresces brightly even when oxygen levels in cells are low. This could be useful for visualizing anaerobic areas inside cancerous tumours, says Campbell.


In 2007, a different group of researchers found a fluorescent protein in the lancelet, a tiny somewhat eel-like marine creature closely related to vertebrates. But that protein is in the same class as those found in corals and jellyfish.


Japanese freshwater eels mature in rivers and travel far out to sea to spawn, and UnaG may help them with long-distance migrations by playing a role in muscle function. European and American freshwater eels (Anguilla anguilla and Anguilla rostrata) also migrate long distances, and Miyawaki and his colleagues found that these eels, too, make UnaG. Young Japanese eels, which migrate from sea to rivers, produce the protein in abundance, so that they glow beautifully when illuminated with a blue light, says Miyawaki. 

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3 Billion Year Old Plankton Microfossils Found in Australia

3 Billion Year Old Plankton Microfossils Found in Australia | Amazing Science |

Scientists have recently found oddly spindle-shaped microfossils in 3 billion year old rock in Australia.“It is surprising to have large, potentially complex fossils that far back,” said study lead author Prof Christopher House from Penn State University.


The microfossils are reported to be planktonic autotrophs who were approximately twenty to sixty microns in length– and freely floated through out the ocean producing energy, according to the study published in the journal Geology. The researchers looked at surrounding rocks (Farrel Quartzite) to determine the age of the fossils, and came up with their stable carbon isotope ratios.


The ratio of Carbon 13 (The component used to determine the age of life by measuring the half-lives of isotopes) was indicative of life. Life forms throughout life gather up more carbon 12 to incorporate into themselves which creates a certain signature of biological processes. Researchers looked at surrounding rock to determine if it was a fluke, and indeed the surrounding area was different from the microfossils.


“The spindles appear to be the same as those found in rocks from the Strelly Pool Formation in Western Australia and the Onverwacht Group in South Africa and Swaziland that are both 3.4 billion years old,” said co-author Dr Dorothy Oehler from Astromaterials Research and Exploration Science Directorate, NASA – Johnson Space Center.

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Only 3% of all bird species have penises, and BMP4 regulates the apoptosis of progenitor cells during development

Only 3% of all bird species have penises, and BMP4 regulates the apoptosis of progenitor cells during development | Amazing Science |

One of the most puzzling events in evolution is the reduction and loss of the penis in birds. All birds reproduce by internal fertilization, but only ∼3% of birds have retained a phallus capable of intromission. A number of hypotheses have been proposed for the evolutionary mechanisms that drove phallus reduction; however, the underlying developmental mechanisms are unknown.


A research team now investigated the genital development in two sister clades of birds, Galliformes (land fowl), most of which lack an intromittent phallus, and Anseriformes (waterfowl), which have well developed phalluses; and in two outgroups, Paleognathae (emus) and Crocodilia (alligators). Galliform embryos undergo cryptic development of a genital tubercle, the precursor of the phallus, but this later undergoes apoptosis, leading to regression of the tubercle. At the molecular level, a derived pattern of Bmp4 expression was identified in chick (a galliform) genital tubercles. Inhibition of Bmp signaling in chick genitalia rescues cells from apoptosis and prevents phallus regression, whereas activation of Bmp signaling in duck (an anseriform) genitalia induces a galliform-like pattern of apoptosis. Thus, distal Bmp activity is necessary and sufficient to induce apoptosis in Galloanserae genital tubercles.


The results indicate that evolutionary reduction of the intromittent phallus in galliform birds occurred not by disruption of outgrowth signals but by de novo activation of cell death by Bmp4 in the genital tubercle. These findings, together with discoveries implicating Bmps in evolution of beak shape, feathers, and toothlessness, suggest that modulation of Bmp gene regulation played a major role in the evolution of avian morphology.

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Yale scientists develop video-rate nanoscopy to peer deep into a cell in real time

Yale scientists develop video-rate nanoscopy to peer deep into a cell in real time | Amazing Science |

A dream of scientists has been to visualize details of structures within our cells in real time, a breakthrough that would greatly aid in the study of their function.  However, even the best of current microscopes can take minutes to recreate images of the internal machinery of cells at a usable resolution.

Thanks to a technical tour de force, Yale University researchers can now generate accurate images of sub-cellular structures in milliseconds rather than minutes.


This image of microtubules, which act as a cellular scaffolding, was captured in just 33 milliseconds. “We can now see research come to life and tackle complex questions or conditions which require hundreds of images, something we have not been able to do before,” said Joerg Bewersdorf, assistant professor of cell biology and biomedical engineering and senior author of the research, published in the journal Nature Methods.

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Researchers reveal how malaria parasite sticks to blood vessels: PfEMP1 binding to EPCR

Researchers reveal how malaria parasite sticks to blood vessels: PfEMP1 binding to EPCR | Amazing Science |

Discovery of how parasite sticks to blood vessels could lead to new means to combat malaria.


Malaria parasites grow in red blood cells and stick to the endothelial lining of blood vessels through a large family of parasite proteins called PfEMP1. This way, the parasite avoids being carried with the blood to the spleen, where it would otherwise be destroyed. One of the most aggressive forms of malaria parasite binds in brain blood vessels, causing a disease called cerebral malaria.


In 2012, three groups of researchers, including the teams at the University of Copenhagen and Seattle Biomedical Research Institute, showed that a specific type of PfEMP1 protein was responsible for cerebral binding and other severe forms of malaria infection. However, until now, the receptor to which it binds remained unknown, and the next big question was to determine which receptors the infected red blood cells were binding to.


“The first big challenge was to generate a full-length PfEMP1 protein in the laboratory,” says Assistant Professor Louise Turner at the University of Copenhagen. “Next, we utilized a new technology developed by Retrogenix LTD in the United Kingdom to examine which of over 2,500 human proteins this PfEMP1 protein could bind to.” Of the 2,500 proteins screened, a receptor called endothelial protein C (EPCR) was the single solid hit.


“A lot of work then went into confirm this binding in the lab and not least to show that parasites from non-immune children with severe malaria symptoms in Tanzania often bound EPCR,” she continues.


“It was a true eureka moment,” says Assistant Professor Thomas Lavstsen. “Under normal conditions, ECPR plays a crucial role in regulating blood clotting, inflammation, cell death and the permeability of blood vessels. The discovery that parasites bind and interfere with this receptor´s normal function may help us explain why severe symptoms of malaria develop."


Severe malaria symptoms such as cerebral malaria often result in minor blood clots in the brain. One of our body´s responses to malaria infection is to produce inflammatory cytokines, but too much inflammation is dangerous, describes Professor Joseph Smith, from the Seattle Biomedical Research Institute.


“ECPR and a factor in the blood called protein C act as a ‘brake’ on blood coagulation and endothelial cell inflammation and also enhance the viability and integrity of blood vessels, but when the malaria parasites use PfEMP1 to bind EPCR, they may interfere with the normal function of EPCR, and thus the binding can be the catalyst for the violent reaction,” he explains.


“Now that we know the pair of proteins involved, we can begin zooming further in to reveal the molecular details of how malaria parasites grab onto the sides of blood vessels. We want to know exactly which bits of the parasite protein are needed to bind to the receptor in the blood vessel wall. Then, we can aim to design vaccines or drugs to prevent this binding.” 

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Interactive Chart: A Century of Cicadas

Interactive Chart: A Century of Cicadas | Amazing Science |
Periodical cicadas live underground for 17 or 13 years before emerging to sing, mate and die. This year’s cicadas are Brood II, one of 15 surviving regional broods.
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Flavor network and the principles of food pairing

Flavor network and the principles of food pairing | Amazing Science |

The cultural diversity of culinary practice, as illustrated by the variety of regional cuisines, raises the question of whether there are any general patterns that determine the ingredient combinations used in food today or principles that transcend individual tastes and recipes. We introduce a flavor network that captures the flavor compounds shared by culinary ingredients. Western cuisines show a tendency to use ingredient pairs that share many flavor compounds, supporting the so-called food pairing hypothesis. By contrast, East Asian cuisines tend to avoid compound sharing ingredients. Given the increasing availability of information on food preparation, our data-driven investigation opens new avenues towards a systematic understanding of culinary practice.

As omnivores, humans have historically faced the difficult task of identifying and gathering food that satisfies nutritional needs while avoiding foodborne illnesses. This process has contributed to the current diet of humans, which is influenced by factors ranging from an evolved preference for sugar and fat to palatability, nutritional value, culture, ease of production, and climate. The relatively small number of recipes in use (∼10E6, e.g. compared to the enormous number of potential recipes (>10E15), together with the frequent recurrence of particular combinations in various regional cuisines, indicates that we are exploiting but a tiny fraction of the potential combinations. Although this pattern itself can be explained by a simple evolutionary model or data-driven approaches, a fundamental question still remains: are there any quantifiable and reproducible principles behind our choice of certain ingredient combinations and avoidance of others?


Although many factors such as colors, texture, temperature, and sound play an important role in food sensation, palatability is largely determined by flavor, representing a group of sensations including odors (due to molecules that can bind olfactory receptors), tastes (due to molecules that stimulate taste buds), and freshness or pungency (trigeminal senses). Therefore, the flavor compound (chemical) profile of the culinary ingredients is a natural starting point for a systematic search for principles that might underlie our choice of acceptable ingredient combinations.


A hypothesis, which over the past decade has received attention among some chefs and food scientists, states that ingredients sharing flavor compounds are more likely to taste well together than ingredients that do not (for more info, see This food pairing hypothesis has been used to search for novel ingredient combinations and has prompted, for example, some contemporary restaurants to combine white chocolate and caviar, as they share trimethylamine and other flavor compounds, or chocolate and blue cheese that share at least 73 flavor compounds. As we search for evidence supporting (or refuting) any ‘rules’ that may underlie our recipes, we must bear in mind that the scientific analysis of any art, including the art of cooking, is unlikely to be capable of explaining every aspect of the artistic creativity involved. Furthermore, there are many ingredients whose main role in a recipe may not be only flavoring but something else as well (e.g. eggs' role to ensure mechanical stability or paprika's role to add vivid colors). Finally, the flavor of a dish owes as much to the mode of preparation as to the choice of particular ingredients. However, one hypothesis is that, given the large number of recipes we use in our analysis (56,498), such factors can be systematically filtered out, allowing for the discovery of patterns that may transcend specific dishes or ingredients.

Anna V. A. Resurreccion's comment, June 5, 2013 4:41 PM
Interesting analyses of flavors; looking at similarities and dissimilar patterns. Garlilc appears to be common to all but North Aerican diets. I hope the authors will include AFRICA. This study might unlock the key to introducing nutrition in diets of populations worldwide.
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Scientific team picks apart 3D structure of HIV shell

Scientific team picks apart 3D structure of HIV shell | Amazing Science |

The first description of the 4-million-atom structure of the HIV’s capsid, or protein shell, could lead to new ways to fight the virus. “The capsid is critically important for HIV replication, so knowing its structure in detail could lead us to new drugs that can treat or prevent the infection,” says senior author Peijun Zhang, associate professor of structural biology at the University of Pittsburgh School of Medicine. “This approach has the potential to be a powerful alternative to our current HIV therapies, which work by targeting certain enzymes, but drug resistance is an enormous challenge due to the virus’ high mutation rate.”

Previous research has shown that the cone-shaped shell is composed of identical capsid proteins linked together in a complex lattice of about 200 hexamers and 12 pentamers, Zhang says.


But the shell is non-uniform and asymmetrical; uncertainty remained about the exact number of proteins involved and how the hexagons of six protein subunits and pentagons of five subunits are joined.


Standard structural biology methods to decipher the molecular architecture were insufficient because they rely on averaged data, collected on samples of pieces of the highly variable capsid to identify how these pieces tend to go together.


Instead, the team used a hybrid approach. They took data from cryo-electron microscopy at an 8-angstrom resolution (a hydrogen atom measures 0.25 angstrom) to uncover how the hexamers are connected, and cryo-electron tomography of native HIV-1 cores, isolated from virions, to join the pieces of the puzzle.


Collaborators at the University of Illinois then used their new Blue Waters supercomputer to run simulations at the petascale, involving 1 quadrillion operations per second, that positioned 1,300 proteins into a whole that reflected the capsid’s known physical and structural characteristics.


The process revealed a three-helix bundle with critical molecular interactions at the seams of the capsid, areas that are necessary for the shell’s assembly and stability, which represent vulnerabilities in the protective coat of the viral genome.


“The capsid is very sensitive to mutation, so if we can disrupt those interfaces, we could interfere with capsid function,” Zhang says. “The capsid has to remain intact to protect the HIV genome and get it into the human cell, but once inside it has to come apart to release its content so that the virus can replicate.


“Developing drugs that cause capsid dysfunction by preventing its assembly or disassembly might stop the virus from reproducing.”

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Genetic Scientists Eliminate Schizophrenia Symptoms in Mice by Targeting Neuregulin-1 (NRG1)

Genetic Scientists Eliminate Schizophrenia Symptoms in Mice by Targeting Neuregulin-1 (NRG1) | Amazing Science |

Geneticists writing in the journal Neuron reversed schizophrenia-like symptoms in adult mice by restoring normal expression to the gene Neuregulin-1 (NRG1).


Targeting expression of NRG1, which makes a protein important for brain development, may hold promise for treating at least some patients with the brain disorder. Like patients with schizophrenia, adult mice biogenetically-engineered to have higher NRG1 levels showed reduced activity of the brain messenger chemicals glutamate and γ-aminobutyric acid (GABA). The mice also showed behaviors related to aspects of the human illness.

“They genetically engineered mice so they could turn up levels of NRG1 to mimic high levels found in some patients then return levels to normal,” explained senior author Dr Lin Mei from the Medical College of Georgia at Georgia Regents University.


“They found that when elevated, mice were hyperactive, couldn’t remember what they had just learned and couldn’t ignore distracting background or white noise. When they returned NRG1levels to normal in adult mice, the schizophrenia-like symptoms went away.”


While schizophrenia is generally considered a developmental disease that surfaces in early adulthood, the team found that even when they kept NRG1 levels normal until adulthood, mice still exhibited schizophrenia-like symptoms once higher levels were expressed. Without intervention, they developed symptoms at about the same age humans do.


“This shows that high levels of NRG1 are a cause of schizophrenia, at least in mice, because when you turn them down, the behavior deficit disappears,” Dr Mei said. “Our data certainly suggests that we can treat this cause by bringing down excessive levels of NRG1 or blocking its pathologic effects.”


“Schizophrenia is a spectrum disorder with multiple causes – most of which are unknown – that tends to run in families, and high NRG1 levels have been found in only a minority of patients. To reduce NRG1 levels in those individuals likely would require development of small molecules that could, for example, block the gene’s signaling pathways,” Dr Mei said.


“Current therapies treat symptoms and generally focus on reducing the activity of two neurotransmitters since the bottom line is excessive communication between neurons.”


The good news is it’s relatively easy to measure NRG1 since blood levels appear to correlate well with brain levels. To genetically alter the mice, the scientists put a copy of the NRG1 gene into mouse DNA then, to make sure they could control the levels, they put in front of the DNA a binding protein for doxycycline, a stable analogue for the antibiotic tetracycline, which is infamous for staining the teeth of fetuses and babies. The mice are born expressing high levels of NRG1 and giving the antibiotic restores normal levels.


“If you don’t feed the mice tetracycline, the NRG1 levels are always high. Endogenous levels of the gene are not affected. High-levels of NRG1 appear to activate the kinase LIMK1, impairing release of the neurotransmitter glutamate and normal behavior. The LIMK1 connection identifies another target for intervention,” Dr Mei concluded.

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