Sweating, panting, moving to the shade, or taking a dip are all time-honored methods used by animals to cool down. The implicit goal of these adaptations is always to keep the brain from overheating. Now a new study shows that armor-plated dinosaurs (ankylosaurs) had the capacity to modify the temperature of the air they breathed in an exceptional way: by using their long, winding nasal passages as heat transfer devices.
Led by paleontologist Jason Bourke, a team of scientists at Ohio University used CT scans to document the anatomy of nasal passages in two different ankylosaur species. The team then modeled airflow through 3D reconstructions of these tubes. Bourke found that the convoluted passageways would have given the inhaled air more time and more surface area to warm up to body temperature by drawing heat away from nearby blood vessels. As a result, the blood would be cooled, and shunted to the brain to keep its temperature stable.
Modern mammals and birds use scroll-shaped bones called conchae or turbinates to warm inhaled air. But ankylosaurs seem to have accomplished the same result with a completely different anatomical construction.
"There are two ways that animal noses transfer heat while breathing," says Bourke. "One is to pack a bunch of conchae into the air field, like most mammals and birds do--it's spatially efficient. The other option is to do what lizards and crocodiles do and simply make the nasal airway much longer. Ankylosaurs took the second approach to the extreme."
Lawrence Witmer, who was also involved with the study, said, "Our team discovered these 'crazy-straw' airways several years ago, but only recently have we been able to scientifically test hypotheses on how they functioned. By simulating airflow through these noses, we found that these stretched airways were effective heat exchangers. They would have allowed these multi-tonne beasts to keep their multi-ounce brains from overheating."
Like our own noses, ankylosaur noses likely served more than one function. Even as it was conditioning the air it breathed, the convoluted passageways may have added resonance to the low-pitched sounds the animal uttered, allowing it to be heard over greater distances.
From Science Daily
Nov 8, 2014
Origin of the unique ventilatory apparatus of turtles: How the tortoise's ribs got embedded in its shell
Lead author Dr Tyler Lyson of Wits University's Evolutionary Studies Institute, the Smithsonian Institution and the Denver Museum of Nature and Science said: "Tortoises have a bizarre body plan and one of the more puzzling aspects to this body plan is the fact that tortoises have locked their ribs up into the iconic tortoise shell. No other animal does this and the likely reason is that ribs play such an important role in breathing in most animals including mammals, birds, crocodilians, and lizards."
Instead tortoises have developed a unique abdominal muscular sling that wraps around their lungs and organs to help them breathe. When and how this mechanism evolved has been unknown.
"It seemed pretty clear that the tortoise shell and breathing mechanism evolved in tandem, but which happened first? It's a bit of the chicken or the egg causality dilemma," Lyson said. By studying the anatomy and thin sections (also known as histology), Lyson and his colleagues have shown that the modern tortoise breathing apparatus was already in place in the earliest fossil tortoise, an animal known as Eunotosaurus africanus.
This animal lived in South Africa 260 million years ago and shares many unique features with modern day tortoises, but lacked a shell. A recognisable tortoise shell does not appear for another 50 million years.
Lyson said Eunotosaurus bridges the morphological gap between the early reptile body plan and the highly modified body plan of living tortoises, making it the Archaeopteryx of turtles.
"Named in 1892, Eunotosaurus is one of the earliest tortoise ancestors and is known from early rocks near Beaufort West," said Professor Bruce Rubidge, Director of the Evolutionary Studies Institute at Wits University and co-author of the paper.
"There are some 50 specimen of Eunotosaurus. The rocks of the Karoo are remarkable in the diversity of fossils of early tortoises they have produced. The fact that we find Eunotosaurus at the base of the Karoo succession strongly suggest that there are more ancestral forms of tortoises still to be discovered in the Karoo," Rubidge added.
The study suggests that early in the evolution of the tortoise body plan a gradual increase in body wall rigidity produced a division of function between the ribs and abdominal respiratory muscles. As the ribs broadened and stiffened the torso, they became less effective for breathing which caused the abdominal muscles to become specialised for breathing, which in turn freed up the ribs to eventually -- approximately 50 million years later -- to become fully integrated into the characteristic tortoise shell.
Read more at Science Daily
Nov 7, 2014
The dodo was a flightless bird about 3 feet (1 meter) tall that was native to the island of Mauritius in the Indian Ocean. It went extinct by 1693, less than a century after the Dutch discovered the island in 1598, killed off by creatures such as rats and pigs, which sailors introduced to Mauritius either accidentally or intentionally.
The giant bird was actually a type of pigeon. "The skull of the dodo is so large and its beak so robust that it is easy to understand that the earliest naturalists thought it was related to vultures and other birds of prey, rather than the pigeon family," said study co-author Hanneke Meijer at the Catalan Institute of Paleontology in Spain.
Surprisingly, despite the dodo's fame, and the fact the bird was alive during recorded human history, little is known about the anatomy and biology of this animal. "The dodo's extinction happened at a time when people didn't understand the concept of extinction — science as we know it was still in its infancy,"lead study author Leon Claessens, a vertebrate paleontologist at the College of the Holy Cross in Worcester, Massachusetts, told Live Science. "This meant that nobody tried to make a collection of the bird or study it in detail."
To shed new light on the dodo, Claessens and his colleagues went to the Natural History Museum in Port Louis, Mauritius, to investigate the only known complete skeleton from a single dodo. All other dodo skeletons are composites of several birds.
Amateur naturalist and barber Etienne Thirioux found the specimen the researchers analyzed near Le Pouce Mountain on Mauritius in about 1903. It was unstudied by scientists until now.
The scientists used a laser scanner to create a 3D digital model of the specimen. In addition, they scanned a second dodo skeleton Thirioux also created, a composite of two or more skeletons that was housed at the Durban Museum of Natural Science in South Africa.
"We discovered that the anatomy of the dodo we were looking at was not previously described in detail," Claessens said. "There were bones of the dodo that were just unknown to science until now."
"The 3D laser surface scans we made of the fragile Thirioux dodo skeletons enabled us to reconstruct how the dodo walked, moved and lived to a level of detail that has never been possible before," Claessens said. "There are so many outstanding questions about the dodo bird that we can answer with this new knowledge."
For instance, by discovering new dodo knee and ankle bones, "we can learn a lot about how it moved," Claessens said. "It will make a tremendous difference in calculations of the muscle force the dodo could have generated."
The researchers also found that the dodo's breastbone, or sternum, lacked a keel, unlike the Rodrigues solitaire, a closely related extinct flightless pigeon that was known to have used its wings in combat. This suggests that dodos fought each other less than Rodrigues solitaires fight each other.
The smaller ancestors of the dodo must have flown to Mauritius no more than 8 million years ago, when geologists suggest the volcanic island was born. Animals on islands often grow to gigantic sizes when they do not face the same competition as they do on the mainland.
"The dodo must have experienced a fourfold increase in body mass compared to its ancestors, if not an eightfold increase," Claessens said. "If that happened in 8 million years or less, that's a rapid increase. It raises the question of how the dodo would have continued to evolve if it weren't for humans."
Read more at Discovery News
It's possible that the animals satiated their thirst at different times, but left their track marks all in the same area, the researchers said.
The ancient track marks were discovered at Angola's Catoca diamond mine, the fourth-largest diamond mine in the world. The mammalian tracks are a particularly rare find, as most warm-blooded animals at that time were no larger than rats, and this one appears to be larger, researchers said.
"Mammals evolved from very small-sized individuals," said Marco Marzola, a paleontologist with the PaleoAngola Project, an international program investigating vertebrate paleontology in Angola. "The first mammals were the size of a squirrel or even smaller, like a mouse. They evolved to become bigger in size, but only after the time of the dinosaurs."
Geologist Vladimir Pervov, who works for the Sociedade Mineira de Catoca, first spotted the 69 animal tracks in December 2010. In addition, 18 dinosaur tracks, likely from a sauropod, and one with preserved skin impressions, were found in two nearby tracks.(Sauropods were long-necked dinosaurs and the largest animals ever to walk the Earth.)
But the ground is hard and cold in December, making the tracks difficult to study. Pervov contacted the scientists working on the PaleoAngola Project, who then asked representatives for the diamond mine to help them preserve the footprints.
"Incredibly, the society of Catoca stopped all activity in that sector of the mine," Marzola told Live Science. "(They) renounced potential income from their own mine just to promote science — to promote vertebrate paleontology in Angola and in Africa."
Eight months later, in July 2011, a team of paleontologists came to the mine to study the fossilized prints. Ripple marks in the stone surrounding the fossils suggest a shallow lake may have attracted the animals — the first record of Cretaceous vertebrates in inland Angola,the researchers said.
The mammal tracks, about 30 to 35 in total, provide a rare glimpse of the raccoon-size creature. It had five fingers and five toes, with digits up to 0.6 inches (1.5 centimeters) long, on its hands and feet. As on humans, its longest digit was in the middle, Marzola said.
The mammal also walked like a human and a bear — that is, using most of the foot — instead of walking on its toes, like a cat or dog, or on a hoof, like a horse. The digits show blunt tips, suggesting the mammal did not have claws, Marzola said.
Measuring about 1.1 by 1.3 inches (2.7 by 3.2 cm), the prints suggest that the raccoon-size trackmaker was "exceptionally large for its time," Marzola said.
The researchers compared the creature to Repenomamus, a genus that includes two mammalian species from the Cretaceous period that were between 17 and 27 inches (42 and 68 cm) long. But the Repenomamus fossils are from China, and are 4 million to 7 million years younger than the Angolan tracks. Furthermore, the fossils are missing their hands and feet, so scientists cannot compare them with the tracks at Catoca, Marzola said.
Researchers have scant evidence of mammals from the time of the dinosaurs, and most of what they do have consists of teeth and ear bones, Marzola said.
"We don't have a single skeleton that can be compared in size to such a big animal like [the one] that left those tracks," Marzola said. The findings show how rare fossilized footprints can help researchers learn about these elusive animals, he said.
The team also examined 10 preserved tracks from a crocodilomorph, a group that includes modern and extinct crocodiles and their cousins. The animal had four, curved digits that each ended with a claw mark. They also had a handprint that is laterally rotated about 150 degrees to the side, Marzola said.
"This might look like a bizarre characteristic, but it's not so uncommon," he said. "This characteristic was also found in other track ways that are associated with crocodilomorph of the early Jurassic in North America and France, and the early Cretaceous in Spain."
The crocodilomorph's front feet measure 1.2 by 1.3 inches (3 by 3.4 cm), and its rear feet are slightly larger, at 2 by 1.5 inches (5.3 by 3.7 cm).
Read more at Discovery News
The origin of contemporary Europeans continues to be debated. The modern human ancestors of contemporary Eurasians are believed to have left Africa about 50,000 to 60,000 years ago, but how these earliest Eurasians contributed to the modern European gene pool remains unclear.
To shed light on the origins of modern Europeans, scientists analyzed DNA from the left shinbone of a skeleton, known as K14, which was excavated in 1954. K14 is one of the oldest fossils of a European modern human — a man who lived between 36,200 and 38,700 years ago in the area that's now Kostenki, in western Russia. That region is known for its mammoth structures, "circles made of mammoth bones that would have been the base of tents, huts, hearths, lithic and bone artifacts, as well as personal ornaments and figurines," said study co-author Marta Mirazón Lahr, a paleoanthropologist at the University of Cambridge in England.
The researchers sequenced K14's complete genome, making it the second-oldest modern human genome ever sequenced. The oldest yet was from the 45,000-year-old thighbone of a man found in western Siberia.
Surprisingly, the researchers found that contemporary Europeans shared genetic continuity with ancient Europeans.
"Virtually all the major genetic components you find in contemporary Europeans are present among the earliest Europeans," said lead study author Eske Willerslev, an evolutionary biologist at the University of Copenhagen in Denmark. "I don't think many would have predicted this."
The scientists discovered that for millennia, Europe may have been home to a so-called "metapopulation" of modern humans — a group of distinct, separate populations that regularly mixed, grew and fragmented. The genetic contributions of the earliest Eurasians to modern European populations may not have arrived through a few distinct migrations from Asia to Europe, but instead through gene flow in various directions.
"We have to revise our understanding of how the genetic diversity in contemporary Europeans came about," Willerslev told Live Science. "Early Europeans were part of a metapopulation stretching all the way to Central Asia, and through a complex network of sexual exchange, contemporary European populations were created."
All in all, Europeans maintained genetic continuity from their earliest establishment out of Africa until Middle Eastern farmers arrived in the last 8,000 years, bringing with them agriculture and a lighter skin color, the researchers said.
"While people have moved in and out of Asia and Europe, including in the recent past, the genome of Kostenki reveals, for the first time, the extraordinary continuity of Europeans," Mirazón Lahr said.
Indeed, the major components of the modern European genome may date farther back than scientists had thought, all the way to the Upper Paleolithic Era, between 50,000 and 10,000 years ago, the researchers said. The fact that there was genetic continuity during this span of time is remarkable because "this period corresponds to the most extreme climate modern human populations ever lived through, particularly pronounced in Europe," Mirazón Lahr told Live Science. "For 30,000 years, ice sheets came and went, at one point covering two-thirds of Europe," she said.
The new study also found that K14's DNA is similar to that of a 24,000-year-old boy that was found in central Siberia, as well as to that of contemporary western Siberians and many Europeans, but not to the DNA of eastern Asians. This finding reveals that western Eurasian and East Asian lineages had already split from each other by about 37,000 years ago.
There had been much debate among scientists about when western Eurasian and East Asian lineages diverged, "ranging from very recent split times to very old," Willerslev said. "We exclude the possibility of a very recent split."
K14 also harbored about 1 percent more Neanderthal DNA than modern humans. K14 was expected to possess more Neanderthal DNA than is present in people today, since any Neanderthal ancestry that modern humans might have should have diluted over time, once Neanderthals went extinct.
Genetic data from K14 suggest that modern humans and Neanderthals interbred about 54,000 years ago, before the modern human population in Eurasia began to separate. This is why 1.5 to 2.1 percent of the DNA of anyone today with Eurasian ancestry — from Europe to Asia to the Americas — is Neanderthal in origin.
Read more at Discovery News
That’s real cute, says the nudibranch, but I started pulling those moves ages ago—on deadly sea creatures. All over our world’s oceans, the many astoundingly colored species of nudibranch are eating things like the vicious Portuguese man o’ war, incorporating their stingers or toxins into their own skin, and using them to fend off predators. This is an Eminem slug if there ever was one (Eminem, if you’re reading this I’m sorry please don’t hurt me), only instead of appropriating mean words, it’s stealing wonderfully evolved weapons and using them to its advantage.
Nudibranchs are bizarre mollusks that have made a tradeoff: Lose the blasé shell, which takes gobs of energy and resources to construct, in exchange for a far more sinister defense. Different species have become specialized in sequestering the various defenses of both stinging and toxin-coated critters, “which is great because it saves them a lot of energy from having to create these defense mechanisms on their own,” said biologist Shayle Matsuda of the California Academy of Sciences.
How exactly they’re able to absorb the defenses of other animals is not yet clear. What we do know is that some nibble on sponges, others corals, and still others jellyfish, moving their prey’s defensive stingers or chemicals through their own digestive system, out through the walls of the gut, and into sacs on the skin. Here they lie ready to inflict agony on anything that didn’t get the very clear memo not to attack these things.
|Bright colors mean “don’t touch me” and “I’m ready for spring fashion lines.”|
Perhaps the most spectacular of all nudibranchs is the so-called blue dragon (shown at the top), a gorgeous little species with starburst projections known as cerata. Like all nudibranchs, it tracks down its food not so much with sight, but instead with chemical cues. (And unlike the vast majority of nudibranchs, it actually gets its lazy butt off the seafloor and into the water column. Another species, the Spanish dancer shown in the video below, does the same in a rather more spastic manner.) The blue dragon specializes in attacking the Portuguese man o’ war, which is not technically a jellyfish, but a colonial siphonophore made up of thousands of cloned individuals. The man o’ war floats on the surface thanks to a gas-filled chamber, and the blue dragon approaches it in a most remarkable way.
You’re probably wondering by now how exactly the nudibranchs are able to get away with this scalawag behavior without getting stung or poisoned. Well, they are suffering a bit actually, but they have adaptations to deal with the attack. “Some of them have a mucus that helps to stop that, or internal plates that will help lessen the punch toward them,” said Matsuda. (Interestingly, another totally unrelated creature that eats jellies, the incredible ocean sunfish, uses the same mucus defense.)
Some nudibranchs, though, don’t hunt such resilient game. Certain species opt to gobble up algae and end up stealing their chloroplasts, the bits of plant cells where photosynthesis takes place, and store them in their skin. Indeed, these nudibranchs are a lovely bright green, and may in fact be partly solar-powered, though Matsuda notes that there’s still quite a bit of debate on whether the nudibranchs are able to actually draw energy from the chloroplasts.
|Nudibranch egg ribbons are the closest you can get to an underwater rose…that’ll explode at some point with thousands of baby sea slugs.|
Read more at Wired Science
Nov 6, 2014
The still-furry beast is one of the most complete frozen mummies ever found. It literally freezes in time the appearance and anatomy of a steppe bison (Bison priscus), whose species went extinct shortly after the end of the Ice Age.
It’s been named the “Yukagir bison mummy,” after the region where it was found.
“The exceptionally good preservation of the Yukagir bison mummy allows direct anatomical comparisons with modern species of bison and cattle, as well as with extinct species of bison that were gone at the Pleistocene-Holocene boundary,” co-author Evgeny Maschenko from the Paleontological Institute in Moscow was quoted as saying in a press release.
The remarkable specimen still has its complete brain, heart, blood vessels and digestive system. Some of its organs have significantly shrunk over time, but that’s to be expected given its advanced age.
The researchers, led by Natalia Serduk of the Russian Academy of Sciences in Moscow, conducted a necropsy on the remains. The investigation determined that the bison showed a relatively normal anatomy. A clue to its demise, however, is a lack of fat around its abdomen. This suggests that the bison died from starvation, but the scientists aren’t sure of that yet.
Compared to today’s bison in America, the Ice Age bison sported much larger horns and a second back hump. Steppe bison like this now-frozen one were commonly featured in Stone Age cave art, often shown being hunted by humans.
Remains for a woolly rhino, a 35,000–39,000-year-old horse, and a mammoth were also recently found near the Siberian site where the bison mummy was discovered.
Read more at Discovery News
Consisting of carved intersecting lines and symbols, the witch marks were found in a bedroom at Knole, a huge, stately home in Kent which is considered one of the country’s most precious historic houses.
Acquired by the Archbishops of Canterbury in the 15th century and gifted to Henry VIII and remodeled in the 17th century by the Sackville family, the house was the birthplace of poet and gardener Vita Sackville-West and the setting for Virginia Woolf’s novel Orlando.
The markings had not been mentioned in any documents and remained hidden for more than four centuries. They came to light recently during restoration work by the Museum of London Archaeology (MOLA).
Using dendrochronology, or tree ring dating, the archaeologists were able to precisely date the marks to early 1606 and the reign of King James I.
They concluded the witch marks were carved to ward off evil and prevent demonic possession in the period of superstition and paranoia that gripped England after the failed Gunpowder Plot of 1605.
At that time, a handful of English Roman Catholic dissenters, led by Guy Fawkes, planned to blow up King James I of England and and both Houses of Parliament.
Government propaganda, orchestrated by James I, blamed the Catholic conspirators as being in service to Satan, paving the way to widespread accusations of demonic forces and witches at work.
“King James I had a keen interest in witchcraft and passed a witchcraft law, making it an offense punishable by death and even wrote a book on the topic entitled Daemonologie,” James Wright, buildings archaeologist at MOLA, said.
The researchers believe that craftsmen working for Thomas Sackville, Lord Treasurer to James I who at that time owned Knole, carved the marks in a planned system prior to the construction the room. The witch marks, also known as apotropaic marks, were added in anticipation of a visit from the king, with the intention of protecting him from evil spirits.
The marks emerged on beams and joists as archaeologists took up floorboards in the bed chamber prepared for James but also around the fireplace, considered a weak spot in the fight against witches.
“These marks illustrate how fear governed the everyday lives of people living through the tumultuous years of the early 17th century,” Wright said.
Read more at Discovery News
Observed by the powerful Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, this is the most detailed view of the proto-planetary disk surrounding a young star 450 light-years away. And those concentric rings cutting through the glowing gas and dust? Those, my friends, are tracks etched out by planets being spawned inside the disk.
In short, this is the mother of all embryonic star system ultrasounds. But this dazzling new observation is so much more — it’s a portal into our solar system’s past, showing us what our system of planets around a young sun may have looked like over 4 billion years ago. And this is awesome, because it proves that our theoretical understanding about the evolution of planetary systems is correct.
However, there are some surprises.
“These features are almost certainly the result of young planet-like bodies that are being formed in the disc. This is surprising since such young stars are not expected to have large planetary bodies capable of producing the structures we see in this image,” said Stuartt Corder, ALMA Deputy Director.
“When we first saw this image we were astounded at the spectacular level of detail,” said Catherine Vlahakis, ALMA Deputy Program Scientist. “HL Tauri is no more than a million years old, yet already its disc appears to be full of forming planets. This one image alone will revolutionize theories of planet formation.”
As these embryonic planetary bodies orbit the star, they clear a track in the remaining disk of dust, ‘vacuuming’ up the remaining debris with their increasing gravitational dominance, continuing to bulk up their mass.
And this is exactly what we are seeing here. HL Tauri has a protoplanetary disk that is being populated with planets carving out their individual orbital paths. Eventually, the majority of the dust in HL Tauri will be consumed by the growing population of asteroids and planets, maturing into a stable star system like ours. However, the star system seems to be growing up fast, a puzzle that astronomers will no doubt be trying to understand for some time to come.
ALMA is nearing completion and this is the first precision observation in it’s near-fully commissioned configuration. Using the technique of long-baseline interferometry, ALMA is composed of many individual antennae spread over a large area. The distance between the antennae mimics one large antenna spread over a huge area. ALMA can therefore beat the precision of any other observatory on Earth or even in space, including Hubble.
Read more at Discovery News
The researchers were able to replicate that ghostly feeling in a lab by interfering with the sensorimotor input of participants’ brains. When confronted with conflicting sensory-motor signals, some of the participants said they felt up to four ghosts. Some were so disturbed that they asked the experiment to be stopped.
Participants were blindfolded and asked to perform movements with their hands in front of their bodies while a robotic device reproduced their movements and touched their backs. When a delay was introduced between the movement and the robotic touch, it created a distorted spatial perception that led to the ghost illusion, the researchers said.
An MRI analysis confirmed that the participants’ brains were undergoing interference with the three regions associated with self-awareness and sense of spatial position.
“Our experiment induced the sensation of a foreign presence in the laboratory for the first time,” Olaf Blanke, head of the Laboratory of Cognitive Neuroscience at EPFL in Switzerland, said in a press release. “It shows that it can arise under normal conditions, simply through conflicting sensory-motor signals.”
The sensation can occur in patients with mental disorders as well as in healthy individuals placed in extraordinary circumstances, he said.
“Our brain possesses several representations of our body in space,” said lead researcher Giulio Rognini. “Under normal conditions, it is able to assemble a unified self-perception of the self from these representations. But when the system malfunctions because of disease — or, in this case, a robot — this can sometimes create a second representation of one’s own body, which is no longer perceived as ‘me’ but as someone else, a ‘presence’.”
From Discovery News
Nov 5, 2014
The evidence comes thanks to researchers from the University of California, Davis, who have found the remains of an amphibious ichthyosaur in China's Anhui Province.
Ichthyosaurs were marine reptiles from the dinosaur age some 250 million years ago. Before this find, there was no fossil evidence of the time when they were moving toward life at sea.
"But now we have this fossil showing the transition," said the paper's lead author, Ryosuke Motani, a professor in the U.C. Davis department of earth and planetary sciences, in a press release. "There's nothing that prevents it from coming onto land."
The fossil has been dated to 248 million years ago, during the Triassic period (250 to 200 million years ago) and is about 1.5 feet long.
The new ichthyosaur fossil has marked differences from the ichthyosaurs science has already cataloged, the latter having adapted completely to living at sea. The new find had uncommonly large flippers that were flexible enough to allow the creature to move as though it were at sea while on land. Its wrists, meanwhile, were also flexible enough to enable crawling on land.
The amphibious ichthyosaur also had a short nose that was consistent with that of land reptiles and in contrast with the long, beak-like snouts of sea-dwellking ichthyosaurs.
Read more at Discovery News
The research, reported in the journal Nature, helps explain the genesis of external genitalia. It turns out that reptile and mammal genitalia have at least some things in common.
The researchers found that the development of limbs and external genitalia are linked. In snakes and lizards, the external genitalia are made from the same tissue from which the reptile’s hind limbs (or remnants, as with snakes) originate.
In mammals, on the other hand, they are made from what’s known as “tail-bud” tissue. This is a knob of embryonic tissue that contributes to the formation of the posterior part of our and other mammals’ bodies.
"While mammal and reptile genitalia are not homologous in that they are derived from different tissue, they do share a 'deep homology' in that they are derived from the same genetic program and induced by the same ancestral set of molecular signals," lead author Clifford Tabin said in a press release.
Tabin, a professor at Harvard Medical School's Department of Genetics, and his team examined how genitalia first develop in the embryos of certain animals, including snakes and chickens.
Before the genitalia emerge, the embryonic cloaca (tissue that eventually develops into the urinary and gut tracts) issues molecular signals that tell neighboring cells and tissues to form into external genitalia. The researchers discovered that the cloaca's location determines which tissues receive the signal first.
Read more at Discovery News
Egyptian news website Ahram reports that the illegal excavation revealed the remains of a temple from the reign of Pharoah Tuthmose III.
The dig revealed huge limestone blocks covered in hieroglyphics, which belong to a massive temple, according to Egypt's Antiquities Minister Mamdouh El-Damaty.
Ahram reports that two marble columns were also unearthed, along with seven reliefs and a large armless colossus of a seated person, made from red granite.
Major General Momtaz Fathi, an aide to the interior ministry and a director in Egypt's tourism police, said that the find was made in mid October.
The arrests were made after Egypt's tourism and antiquities police heard about the illegal excavation. Police found diving suits, diving masks and oxygen cylinders when they raided the dig, according to Ahram.
The unearthed artifacts were taken to the nearby archaeological site of Saqqara for restoration and further study. The Hod Zeleikha area of Giza where the illegal dig took place has now been declared an archaeological site, according to El-Damaty, who noted that more of the temple will be excavated.
Tuthmose III, known as "the Napoleon of ancient Egypt" as a result of his military successes, reigned from 1479 to 1425 B.C.
Located on the outskirts of Cairo, Giza is best known as the location of the Great Sphinx and the pyramids.
From Discovery News
Even though time is such a fundamental part of our experience, the basic laws of physics don’t seem to care in which direction it goes. For example, the rules that govern the orbits of planets work the same whether you go forward or backward in time. You can play the motions of the solar system in reverse and they look completely normal; they don’t violate any laws of physics. So what distinguishes the future from the past?
“The problem of the arrow of time has been boggling minds forever,” said Flavio Mercati of the Perimeter Institute for Theoretical Physics in Waterloo, Canada.
Most people who’ve thought about this arrow of time say it’s determined by entropy, the amount of disorder in a system (like, say, a bowl of cereal, or the universe). According to the second law of thermodynamics, the overall entropy of a closed system must always increase. And time appears to travel in the same direction as rising entropy.
‘It’s just fascinating for us to think that the reason we remember yesterday and not tomorrow is because of conditions near the Big Bang’
When an ice cube in your glass melts and dilutes your lemonade, for instance, entropy increases. When you scramble an egg, entropy increases. Both of these examples are irreversible: you can’t freeze a water ice cube out from your lemonade or unscramble an egg. The sequence of events—and thus time—goes in only one direction.
If time’s arrow follows the increase of entropy, and if the entropy in the universe is always increasing, then it means that at some point in the past, entropy must have been low. Therein lies the puzzle: why was the universe in such a low entropy state in the first place?
According to Mercati and his colleagues, there was no special, initial state at all. Instead, a state that gets time pointing forward arises naturally from a universe dictated by gravity. The researchers make this argument in a paper recently published in the journal Physical Review Letters.
To test their idea, they simulated the universe as a collection of 1,000 particles that interact with one another only by gravity, representing the galaxies and stars that float around the cosmos.
The researchers found that regardless of starting positions and velocities, at some point the particles inevitably find themselves clustered together in a ball before dispersing again. This moment of clumping is equivalent to the Big Bang, when the whole universe was squeezed into an infinitesimally small point.
Instead of using entropy, the researchers describe their system with a quantity they call complexity, which they define as roughly the ratio of the distance between the two particles farthest from each other to the distance between the two particles closest to each other. When the particles are clumped together, complexity is at its lowest.
The key idea, Mercati explains, is that this moment of lowest complexity arises naturally from the group of gravitationally interacting particles—no special initial conditions are needed. Complexity then increases as the particles disperse, representing the expansion of the universe and the forward progress of time.
|A collection of particles interacting via gravity will inevitably bunch together, as seen in the middle panel. This moment of lowest complexity represents the Big Bang, and two arrows of time point forward and backward, to the left and right.|
The idea is similar to one proposed 10 years ago by physicists Sean Carroll and Jennifer Chen of the California Institute of Technology, who were linking the arrow of time with ideas describing inflation, the abrupt and rapid expansion of the universe that happened soon after the Big Bang.
“What’s great about this is that it’s not hand waving,” Carroll said about the new work, which defines a concrete model and explicitly shows how it gives rise to an arrow of time. “It’s just fascinating for us to think that the reason we remember yesterday and not tomorrow is because of conditions near the Big Bang,” he said.
Showing how temporal direction comes from such a simple system that follows classical physics is new, says physicist Steve Carlip of the University of California, Davis.
Eschewing entropy in favor of complexity is also a distinct idea, Mercati says. The problem with entropy is that it’s defined in terms of energy and temperature, which are measured based on some external reference such as a thermometer. In the case of the universe, there’s nothing outside it, so you need a quantity that doesn’t rely on any units of measurement. Complexity, as the researchers define it, is a dimensionless ratio and fits the bill.
That’s not to say that entropy is irrelevant, Mercati says. Our day-to-day experiences with time—like your iced lemonade—do rely on entropy. But when considering time at cosmic scales, you need to think of the universe in terms of complexity, not entropy.
Read more at Wired Science
|Antiquity’s saddest elephant laments the cursive that someone wrote all over it.|
Oh, also, you’ve been lied to. Elephants aren’t afraid of mice. Sorry. I know it was cute and all.
Now, it’d be easy to chalk up these misconceptions to the fact elephants are naturally distributed in Africa and Asia, and Europeans simply didn’t have enough contact with the animals to inform their judgements. The reality, though, is that the elephant has an old (and brutal) history in Europe.
The Foot Bone’s Connected to the Leg bone, the Leg Bone’s Connected to the…Wait, Where’s the Knee Bone?
Let’s start with the elephant’s unfortunate lack of knees, a myth that persisted through the Middle Ages. In his charting of the history of this misconception, imminent 17th century skeptic and all-around ornery fellow Sir Thomas Browne notes that even the ancient Greeks knew this wasn’t so. Western armies first fought elephants at the Battle of Gaugamela in present-day northern Iraq in 331 BC, where Alexander the Great squared off against Darius of Persia. Yes, men fought elephants. The so-called war elephant, you see, was an incredibly effective weapon in ancient warfare—if you could manage to feed them and keep them from stepping on your own soldiers. But Alexander overcame the Persians, captured their elephants, and sent the beasts back to Greece. Having seen elephants for themselves, the Greeks had no reason to doubt their possession of knees.
|Hannibal’s army and their war elephants crossing the Rhône. It’d be way more awesome if not for the inherent cruelty.|
“One of these animals fought in a most astonishing manner; being pierced through the feet, it dragged itself on its knees towards the troop, and seizing their bucklers, tossed them aloft into the air: and as they came to the ground they greatly amused the spectators, for they whirled round and round in the air, just as if they had been thrown up with a certain degree of skill, and not by the frantic fury of a wild beast.”
|An inexplicably tiny war elephant (would seem to defeat the purpose of using an elephant) at top, with wild ones at bottom. From the Rochester bestiary.|
More skeptical natural historians eventually began to question this, though. The 13th century’s Albertus Magnus, for instance, noted that the elephant wasn’t missing knees—it just had stiff joints in its legs, limbs he claimed were the same girth from top to bottom, like pillars of meat. Such robustness, Magnus claimed, was necessary to support its weight.
Dangerous Sex, Slaughtering Mice, and Other Elephantoid Pursuits
The Physiologus also helped disseminate other fanciful elephant “facts” that had been bouncing around intellectual circles in the ancient world. Take for instance, the beast’s odd sex life. According to the book’s anonymous author, when elephants want to conceive, a male and a female must head “to the east near paradise,” where they’ll find the mandrake. This plant’s root has a long history of being used by humans as an aphrodisiac, though as a member of the nightshade family it contains powerful toxins that can kill in high doses. (It was once said to take the form of a human that screamed bloody murder when you pulled it from the ground, killing anything within earshot.) The elephants supposedly give it a nibble, and “the female immediately conceives in the womb.”
|Elephants gather to mate around a mandrake, lower right, which they’ll eat as an aphrodisiac. The voyeuristic dragon is presumably there to watch and eat their babies.|
Not bad for a creature that’s supposedly afraid of the lowly mouse. And for this myth we once again have Pliny to thank, believe it or not. Elephants “hate mice and will refuse to eat fodder that has been touched by one,” he claims. Not so. As a researcher of elephant behavior told LiveScience in 2011: “In the wild, anything that suddenly runs or slithers by an elephant can spook it. It doesn’t have to be a mouse—dogs, cats, snakes or any animal that makes sudden movements by an elephant’s feet can startle it.”
Read more at Wired Science
Nov 4, 2014
On March 3, 1677, the French Navy launched a fierce attack against the Dutch in Tobago's Rockley Bay. European settlers coveted Tobago for its strategic location; in fact, the island changed hands more than 30 times after Christopher Columbus arrived in the New World.
The abbreviated story of this particular battle is, "Everybody dies, and every ship sinks," according to Kroum Batchvarov, an assistant professor of maritime archaeology at the University of Connecticut. Indeed, about 2,000 people were killed and up to 14 ships went down during the skirmish. But until now, none of those sunken vessels had been recovered.
This past March, Batchvarov went searching for wrecks in Rockley Bay. Through remote sensing and historical accounts, his team identified a spot where shipwrecks from the battle might have settled on the bottom of the bay. One day, while the rest of his colleagues were sorting out an issue with their GPS systems, Batchvarov and another diver decided to explore under the surface.
"Quite literally, the first thing we saw at the bottom was a cannon," Batchvarov told a small audience here at the Explorers Club headquarters today (Nov. 3).
During that initial, 20-minute dive, the researchers found at least seven cast-iron cannons, some of them large, 18-pounder guns.
"This was one of the most interesting experiences of my life in archaeology, and I have been in this field for about 17 years," Batchvarov said.
None of the sunken ship's timbers have been uncovered yet from the jumbled wreckage, but divers did find relics from life aboard a military vessel, including 72 clay smoking pipes, an array of dining utensils and burned bricks from the ship's galley. They also found a beer jug with three engravings of military generals from antiquity: Joshua, David and Alexander the Great.
Several clues led the team to conclude they were dealing with a Dutch warship from the 17th century. For example, many of the pipes had the mark of a manufacturer that operated in Amsterdam from the 1650s to the 1680s, Batchvarov said.
Because of the size of the cannons found at the site, the archaeologists suspect the wreck could be the 130-foot-long (40 meters), 56-gun warship Huis de Kreuningen. Only one other Dutch vessel, the flagship Bescherming, could have supported such large guns, but it survived the battle, Batchvarov said.
Read more at Discovery News
But now new research finds that apes -- our closest relative -- have much more varied gut flora than humans do, and especially more varied than people living in the United States.
"It took millions of years, since humans and chimpanzees split from a common ancestor, to become 60 percent different in these colonies living in our digestive systems," said Howard Ochman, professor of integrative biology at The University of Texas at Austin and co-author of the study in a press release.
"On the other hand, in apparently only hundreds of years -- and possibly a lot fewer -- people in the United States lost a great deal of diversity in the bacteria living in their gut."
In fact, those of us living in the United States have intestinal microbes that are 70 percent different than chimps'.
That's not good news: a lack of a varied gut microbiome has been linked to asthma, colon cancer and autoimmune disease. There's also evidence that our intestinal microbiome communicates with our brains and that imbalanced gut flora can mess with our minds, causing depression and other mental illnesses.
Scientists studied fecal samples from humans, chimps, bonobos and gorillas to discover our intestinal differences.
Why have American gut microbes changed so quickly -- hundreds, as opposed to millions, of years? The researchers speculate that we spend more time indoors, use antibacterial cleansers and rely too much on antibiotics (which kill gut flora), to name a few reasons.
Read more at Discovery News
The image above shows just a small part of a huge glowing cloud of hydrogen called Gum 15, located 3,000 light-years away in the southern constellation Vela. The dark areas snaking across it aren’t really smoke but rather lanes of opaque interstellar dust, sculpted by stellar wind and silhouetted against the brightly ionized hydrogen beyond.
This image was taken as part of the ESO Cosmic Gems program with the Very Large Telescope (VLT) located at ESO’s Paranal Observatory in Chile.
The nebula was discovered in 1951 by a young Australian astronomer named Colin Gum, who included it and many others in a now-famous catalog of HII emission nebulae published in 1955. The talented and well-liked Gum suffered a tragic death at the young age of 36 in a skiing accident while vacationing in Switzerland in 1960.
Today, this and 84 other emission nebulae bear his name along with a crater on the moon.
From Discovery News
The space rock smashup showered Earth with up to 100 times more meteorites than today's rate (a rock the size of a football field hits the planet about every 10,000 years). Yet, only a dozen or so impact craters have been found from the ancient bombardment 470 million years ago, during the Ordovician Period. Most are in North America, Sweden and western Russia. There are only about 185 known impact craters on Earth of any age, while the moon has more than 100,000.
But the number of Ordovician craters may soon take off. That's because it's easier and cheaper than ever to hunt down evidence that confirms an impact. The clinchers include shocked minerals, deformed rocks and structural features that match other craters.
"Google Earth images are not good enough to identify an impact structure," noted planetary geologist Christian Köeberl on Oct. 22, at the Geological Society of America's annual meeting in Vancouver, British Columbia. During the Vancouver meeting, researchers presented new clues that bring suspected craters in Wisconsin, Kentucky and Tennessee closer to official listings as Ordovician impact craters.
The three enigmatic structures retain their circular shape, but have lost most of their original features through erosion. In the last century, quarrying has also slowly dismantled the Wisconsin crater. Only the central uplift seems to persist. When a meteorite hits, the impact's force causes the underlying rock to rebound upward, leaving a topographic high in the center of the crater.
In each state, researchers looked for traces of minerals shattered or heated by the impact. So far, no one has found one of the smoking guns in crater research: shatter cones, the finely fractured rocks created when the shock wave travels through the ground. The fractures are often arranged in a conical shape, like an ice cream cone.
Three little craters
But even without a smoking gun, at Brussels Hill in Door County, Wisconsin, a meteorite impact is the best explanation for the perfectly round, 130-foot-tall (40 meters) hill, said Emily Zawacki, an undergraduate at Lawrence University in Appleton, Wisconsin. The flat-topped peak is filled with fractured blocks of Cambrian sandstone that should lie some 1,300 feet below the younger carbonate rocks. The fragmented rocks all tilt toward the center of the hill, and a series of faults radiate outward from its center.
The evidence all points to a deeply eroded impact crater, Zawacki said. "This is a highly disturbed area in otherwise flat-lying stratigraphy," Zawacki said. "It very clearly is anomalous and we feel a meteoritic impact best explains it."
In the middle of Tennessee, the Howell Structure has confounded geologists for decades. The bowl-shaped basin is about the same diameter as Brussels Hill (about 1.2 miles, or 2 km). In this case, however, the suspected crater is weaker than the surrounding rocks, creating a depression. A pile of fragmented carbonate and other craterlike features suggests an impact origin.
Keith Milam, a professor at Ohio University in Athens, recently uncovered a rare trove of rock cores drilled at Howell in the 1960s. John Bensko, a retired lunar geologist from NASA's Marshall Space Flight Center, provided the 15 segments. Bensko oversaw the testing of drilling equipment intended for the canceled Apollo 18 program. The first tests on the rock cores suggest the fragmented carbonate rocks were shocked by a meteorite impact, Milam reported at the Vancouver meeting.
Finally, the Jeptha Knob structure in Kentucky is a site that stands out on Google Earth and just needs the right mineral evidence to certify its impact origin. "I don't think you can say for sure this is an impact structure yet," said Eric Gibbs, an undergraduate at Ohio University in Athens. Gibbs is testing the X-ray diffraction pattern produced by minerals from the crater. The pattern shortens and widens with increasing shock, he said.
The initial tests, presented at the Vancouver geology meeting, support an impact origin for the hill. Jeptha Knob is the highest point in Kentucky's Bluegrass Region, rising some 300 feet (90 m) above the surrounding farms. The round crater is ringed by faults and busted-up Ordovician limestone, but topped by flat layers of younger carbonate rocks.
The apparent alignment of many of these craters makes it seem that some coincidence favored Earth's tropical latitudes during the big Ordovician bombardment.
Read more at Discovery News
Nov 3, 2014
|The core of the Milky Way at a distance of some 26,000 light years from Earth.|
The galactic center is a bustling place. Lots of gas, dust, and stars zip about, orbiting a supermassive black hole about three million times more massive than the sun. With so many stars, astronomers estimate that there should be hundreds of dead ones, says astrophysicist Joseph Bramante of Notre Dame University. Scientists have found only a single young pulsar at the galactic center, where there should be as many as 50 such youngsters.
Bramante and astrophysicist Tim Linden of the University of Chicago have a possible solution to this missing-pulsar problem, which they describe in a paper accepted for publication in the journal Physical Review Letters. Maybe those pulsars are absent because dark matter, which is plentiful in the galactic center, gloms onto the pulsars, accumulating until the pulsars become so dense they collapse into a black hole. Poof. No more pulsars.
A Different Kind of Dark Matter
Dark matter, of course, is the weird stuff that’s everywhere—filling roughly a quarter of the universe—but is invisible and hardly interacts with anything, making its presence known only by how its gravitational pull interacts with other astrophysical objects.
One of the more popular candidates for dark matter is weakly interacting massive particles, or a WIMPs. Underground detectors are hunting for WIMPs and debate has raged over whether gamma rays streaming from the galactic center come from WIMPs annihilating one another. In general, any particle and its antimatter partner will annihilate each other in a flurry of energy. But WIMPs don’t have an antimatter counterpart. Instead, they’re thought to be their own antiparticles, so one WIMP can annihilate a fellow WIMP.
But over the last few years, physicists have considered another class of dark matter called asymmetric dark matter. Unlike WIMPs, this type of dark matter does have an antimatter counterpart.
Asymmetric dark matter appeals to physicists because it’s intrinsically linked to the imbalance of matter and antimatter: There’s a lot more matter in the universe than antimatter (which is a big deal, because without this disparity, everything in the universe—including us—would’ve been annihilated and wouldn’t exist). Likewise, according to the theory, there’s much more dark matter than anti-dark-matter.
Physicists think that in the beginning, the big bang should’ve created as much matter as antimatter. But something altered this balance. No one’s sure what this mechanism was, but it might also have triggered an imbalance in dark matter (hence it is “asymmetric”).
Dark matter is concentrated at the galactic center, and if it’s asymmetric, then it could collect at the center of pulsars, pulled in by gravity. Pulsars are extremely dense—imagine the sun squeezed into a region the size of a small city—so its gravity is strong enough to attract plenty of dark matter. Eventually, the pulsar would accumulate so much mass that it would collapse into a black hole.
The idea that dark matter can cause pulsars to implode isn’t new, says astrophysicist Kathryn Zurek of Lawrence Berkeley National Laboratory. But the new research is the first to apply this possibility to the missing-pulsar problem.
If the hypothesis is correct, Bramante says, then pulsars around the galactic center could only get so old before grabbing so much dark matter that they turn into black holes. Because the density of dark matter drops the farther you go from the center, the researchers predict that the maximum age of pulsars will increase with distance from the center.
Observing this distinct pattern would be strong evidence that dark matter is not only causing pulsars to implode, but also that it’s asymmetric, Bramante says. “The most exciting part about this is just from looking at pulsars, you can perhaps say what dark matter is made of,” he said. Measuring this pattern would also help physicists narrow down the mass of the dark matter particle.
But it won’t be easy to detect this signature. Astronomers will need to collect much more data about the galactic center’s pulsars by searching for radio signals, Bramante says. The hope is that as astronomers explore the galactic center with a wider range of radio frequencies, they will uncover more pulsars.
Still, the idea that dark matter is behind the missing pulsar problem is speculative. How likely is this scenario? “I think it’s unlikely—or at least it is too early to say anything definitive,” said Zurek, who was one of the first to revive the notion of asymmetric dark matter in 2009. The tricky part is being able to know for sure that any measurable pattern in the pulsar population is due to dark-matter-induced collapse and not something else.
Even if astronomers find this pulsar signature, it’s still far from being definitive evidence for asymmetric dark matter, Zurek says. “Realistically, when dark matter is detected, we are going to need multiple, complementary probes to begin to be convinced that we have a handle on the theory of dark matter,” she said.
And asymmetric dark matter may not have anything to do with the missing pulsar problem at all. The problem is relatively new, Bramante says, so astronomers may find more plausible, conventional explanations. “I’d say give them some time and maybe they come up with some competing explanation that’s more fleshed out,” he said.
Nevertheless, the idea is worth pursuing, says Haibo Yu of the University of California, Riverside. If anything, this analysis is a good example of how scientists can understand dark matter by exploring how it may influence astrophysical objects. “This tells us there are ways to explore dark matter that we’ve never thought of before,” he said. “We should have an open mind to see all possible effects that dark matter can have.”
Read more at Wired Science
The wolf, which is wearing an inactive radio collar, could be the first of its species to roam Arizona in 70 years; gray wolves were exterminated from the state in the 1940s.
Federal authorities are investigating the sightings. Representatives from the U.S. Fish and Wildlife Service (FWS) said they are trying to confirm whether the animal is actually a wolf or a "wolf-dog hybrid" by collecting a feces sample.
The animal doesn't appear to be a hybrid, at least in photos taken by observers, but the possibility can't be ruled out until a genetic test is conducted, said Michael Robinson, a wolf advocate with the Center for Biological Diversity, a nonprofit environmental group based in Tucson.
"Until more is known about this animal, visitors to the area are cautioned that this may be a wolf from the northern Rocky Mountain population and fully protected under the Endangered Species Act," FWS representatives said in a statement.
If the wolf did indeed come from the northern Rocky Mountain population, it would have traveled across hundreds of miles to get to northern Arizona; the southernmost breeding population of gray wolves in the Rockies lives just south of Yellowstone National Park in Wyoming, Robinson said.
Gray wolves once lived across most of the continental United States, but the predators were aggressively hunted and sometimes killed for bounties through the early 20th century. By the mid-20th century, the only places gray wolves could be found below the Canadian border were a sliver of land in northern Minnesota and Michigan's Isle Royale.
The species was then protected under the Endangered Species Act in the 1970s. Conservation efforts and reintroduction programs helped gray wolves return to parts of their range. There are now more than 5,000 gray wolves in the continental United States, primarily in the western Great Lakes states of Michigan, Minnesota and Wisconsin, and the northern Rocky Mountain states of Idaho, Montana and Wyoming, as well as eastern Oregon and Washington.
A small population of Mexican wolves (a subspecies of gray wolves) has also been reintroduced to parts of Arizona and New Mexico. The gray wolf spotted in Grand Canyon National Park does not appear to be a Mexican wolf, because its body is bulkier and its ears are more compact than those of a typical Mexican wolf, Robinson said.
The sightings of the Grand Canyon gray wolf are reminiscent of another recent episode involving a wandering male wolf, OR-7, also known as Journey. OR-7 rose to fame in 2012 after he left his pack in Oregon to go to California, becoming the first known wolf in the state in 87 years. Since then, the wolf (which is tracked by a radio collar) has gone back and forth between Oregon and California several times. As of this summer, he was raising his first puppies with a mate.
OR-7's travels raised hopes that California could once again be home to wild wolves. Similarly, the lone wolf in Arizona is an encouraging sign that it's possible for the species to make a comeback in the remote lands around the Grand Canyon.
Unfortunately, many roving wolf stories don't have happy endings. When wildlife officials find out about a wolf that has ventured outside its usual territory, it's often because the creature has been shot or found dead, Robinson said. Last year, coyote hunters shot and killed wolves in Missouri and Kansas. A wolf that wandered from Montana to Colorado in 2009 was killed by poison.
Read more at Discovery News
This news might come as a surprise to New Englanders who didn't think this local spider's bite had any effect on humans. However, Yankees shouldn't be too alarmed. The 50-year-old woman who sustained the spider bite didn't suffer any serious side effects, according to the case study, published in September in the Journal of Medical Entomology.
The victim was reportedly standing in her kitchen, when she felt pain in her leg. She later described the bite as feeling "like the sting of a wasp," said Charles Vossbrinck, one of the co-authors of the report and a scientist at the Connecticut Agricultural Experiment Station, a part of the state's Department of Environmental Sciences, in New Haven. The site of the bite became red and slightly swollen almost immediately. But by the following day, the swelling around the bite had gone down, and the woman didn't require medical attention.
Luckily for scientists who study Connecticut's spiders, the bite victim used a broom to retrieve the fanged culprit from under a kitchen cabinet. She brought the specimen to the Connecticut Department of Environmental Sciences, where Vossbrinck identified it as a broad-faced sac spider (Trachelas tranquillus).
"This is a hunting spider. There are hunting spiders, and then there are those that rely mostly on a web to catch prey," Vossbrinck told Live Science. This means that the broad-faced sac spider is prone to wandering around looking for food, and it may have crawled up the woman's leg while it was taking a stroll through her kitchen, he added.
But the broad-faced spider isn't native to New England kitchens. Most of the time, it prefers the great outdoors, where it can typically be found outside of buildings under siding and on windowsills, as well as at the base of plants, on fences, inside rolled leaves and under stones and boards, according to the College of Agricultural Sciences at Pennsylvania State University.
But because T. tranquillus tends to hang around buildings, there's a chance New Englanders might see these spiders indoors, as well. Connecticut locals typically report seeing the spiders in their homes in the autumn, Vossbrinck said. And T. tranquillus, as well asits cousins that belong to the genus Cheiracanthium, are among the most common spiders found in houses in Boston, according to the case report.
Although the bite victim in this most recent case didn't require medical attention, the first confirmed case of envenomation by the broad-faced sac spider in Connecticut — which occurred in 1969 — suggests that medical attention may be necessary in some instances. In that case, a 23-year-old woman was bitten by one of these spidersand needed antibiotics after the bite became infected. The new case is only the second confirmed case of envenomation by T. tranquillus, the authors noted.
Read more at Discovery News
Now, for the first time, astronomers have surveyed exozodiacal light — the same phenomena, albeit much brighter — in 9 other star systems near their habitable zones.
The observations were made possible through the use of the ESO’s Very Large Telescope Interferometer (VLTI), located at the Paranal Observatory in Chile, in near-infrared light. The interferometer was fed with light from four 1.8-metre Auxiliary Telescopes that imitate a much larger telescope of equivalent diameter as the distance between the telescopes. This allows extreme sensitivity in the observations, distinguishing the faint scattered light extending to the habitable zones surrounding the target stars.
Exozodiacal light has been observed before, but this is the first large-scale survey effort that has scanned dozens of targets.
“If we want to study the evolution of Earth-like planets close to the habitable zone, we need to observe the zodiacal dust in this region around other stars,” said Steve Ertel, of ESO and the University of Grenoble in France. “Detecting and characterizing this kind of dust around other stars is a way to study the architecture and evolution of planetary systems.”
As dust production should diminish over time, the researchers were surprised to find that all the stars with exozodiacal light were in fact older, in contradiction to this idea.
As the exozodiacal light detected in this study is 1,000 times brighter than the zodiacal light in our solar system, the researchers point out that trying to directly image exoplanets within this glow will be made significantly harder. As the glow overlaps those stars’ habitable zones, the detection of Earth-sized exoplanets in habitable zones just became significantly harder — bright exozodiacal light may drown out the exoplanet’s own reflected starlight.
Read more at Discovery News
Nov 2, 2014
The name given to this process by those early biologists, cytokinesis, translates as "cell movement" and captures the sense of a highly active and organized series of events. Scientists have now learned much more about the proteins involved and their behavior, and yet a central mystery remains: How does the cell signal where the furrow should be?
There is a simple reason for that blind spot: It's hard to see and test such a complex feat in living cells. Now Harvard Medical School systems biologists report in Science that they have reconstituted cytokinesis -- complete with signals that direct molecular traffic -- without the cell. Combining frog-egg extracts with lipid membranes that mimic the membrane of the cell, they built a cell-free system that recapitulates how the cleavage furrow is assembled.
This cell-free system has two huge advantages: It expands the scale of the furrow-building events, making them easier to see, and it gives the researchers an easy way to manipulate the proteins involved. Quickly removing and returning proteins to see how changes in the molecular players affect cytokinesis is impossible when the cell is whole, but easy when the cellular innards are spread out on a microscope slide.
The key challenge, though, was that the behavior of cytokinesis is entirely dependent on having a membrane to furrow -- and membranes are exactly what have to be removed to make the system cell-free. What made this work possible was the realization that a controlled, flat membrane -- made from two layers of artificial lipid supported on glass -- could substitute for the curved, constantly moving and complex membrane of the cell.
"We really built what goes on in the cell," said Timothy Mitchison, the Hasib Sabbagh Professor of Systems Biology at HMS. "We believe our work is a step forward, not only for understanding the assembly of the cleavage furrow but also, more generally, for understanding the biophysics of cytokinesis signaling."
The team includes co-senior authors Mitchison and Christine Field, HMS instructor in systems biology, and co-lead authors Phuong Nguyen, a graduate student in chemical biology, and Aaron Groen, a research fellow in systems biology.
Their work began with gently crushing unfertilized egg cells from the Xenopus frog and isolating their internal contents. Scientists have previously used such egg extracts to reconstitute microtubule-based structures called mitotic spindles that align chromosomes properly in preparation for cell division. The HMS team went further.
To start, the scientists turned to their molecular stockpile to come up with such building blocks as artificial centrosomes and fluorescently labeled microtubules. They then mimicked fertilization and added labeled antibodies or proteins to visualize the self-organization of structures required for the cell division process, using fluorescence microscopy in ways that aren't possible with actual living cells in tissue cultures.
The final component was the model of the cell membrane.
"To really prove that we reconstituted the cytokinesis signal, we needed to add the bilayer membrane and then see if it could recruit the proteins that would be on the cortex of the cell," Field said about the specialized layer beneath the cell membrane. "That's the signal to the membrane we were looking for."
The scientists saw this signal in part because Field chose to include actin in their system, a cellular component that is often discarded because it makes it so difficult to do experiments with the egg extract. Actin's job in the cell is to assemble into long filaments and meshworks, like Lego blocks fitting together.
The filaments provide a scaffold that allows other cellular components, including membranes, to move and change shape. So Field reasoned that, despite the difficulty of using actin, it would be important to include it in a system intended to recapitulate the signals involved in membrane furrowing.
"It's not only microtubules signaling to the plasma membrane, but also microtubules signaling to the actin cortex that forms on top of the plasma membrane," Nguyen said. "This phenomenon can be seen only when actin is around."
There are multiple signaling complexes at work in the cleavage furrow, "talking" from the microtubules to the actin cortex and the cell membrane.
Read more at Science Daily