Jul 1, 2016
More than 22 years ago, researchers at Umeå University were first to discover an infection strategy of human pathogenic Yersinia bacteria -- a protein structure in bacterial cell-walls that resembled a syringe. The structure, named "Type III secretion system" or T3SS, makes it possible to transfer bacterial proteins into the host cell and destroy its metabolism.
After the discovery, researchers have found T3SS in several other bacteria species and T3SS has proven to be a common infection mechanism that pathogens, i.e. an infectious agent such as a virus or bacterium, use to destroy host cells. Now, Umeå researchers are again first to find a link between infection and rapid production of the essential proteins needed to form "the poisonous syringe."
Together with researchers at the Helmholtz Centre for Infection Research in Braunschweig, Germany, the Umeå researchers investigated the virulence strategy of Yersinia pseudotuberculosis. This bacterium can cause acute diarrhea, vomiting and stomach pains, and is closely related to the deadly plague bacterium, which it shares many infection mechanisms with. The genes that these bacteria need for infection are located on a circular extra chromosome, called the virulence plasmid.
Researchers at Umeå Centre for Microbial Research (UCMR), The Laboratory for Molecular Infection Medicine Sweden (MIMS) at the Department of Molecular Biology first performed infection experiments in cell cultures with human cells and then confirmed their findings using animal models. It turned out that a single copy of the virulence plasmid was not sufficient to induce infection, but the researchers discovered that when Yersinia came in contact with host cells, it triggered a "copying machine" that increased the number of plasmids.
"Yersinia has developed a very clever strategy," says postdoctoral fellow Helen Wang who carried out a large portion of the experiments. "To carry a great number of plasmids, the bacteria need a lot of energy and it negatively affects the bacteria's metabolism and growth. But having one copy of the plasmid as a blueprint that can be rapidly amplified in case of infection is a very clever solution. Many copies of the plasmids give bacteria the opportunity to build up many T3SS and all the proteins needed to quickly knock out host cells during an infection," continues Helen Wang.
It is the first time researchers can demonstrate that an increased number of plasmid-encoded genes is necessary for successful infection by pathogenic bacteria.
Read more at Science Daily
|Artist's rendering of ULAS J1120+0641, a very distant quasar powered by a black hole with a mass two billion times that of the Sun.|
The energy output of an AGN is often equivalent to that of a whole galaxy of stars. This is an output so intense that most astronomers believe only gas falling in towards a supermassive black hole -- an object with many millions of times the mass of the Sun -- can generate it. As the gas spirals towards the black hole it speeds up and forms a disc, which heats up and releases energy before the gas meets its demise.
Scientists are particularly interested in seeing what happens to the gas as it approaches the black hole. But studying such small objects at such large distances is tricky, as they simply look like points of light in even the best telescopes. Observations with spectroscopy (where light from an object is dispersed into its component colours) show that fast moving clouds of emitting material surround the disc but the true size of the disc and exact location of the clouds are very difficult to pin down.
Bruce will describe how astronomers can make use of cosmic coincidences, and benefit from a phenomenon described by Einstein's general theory of relativity more than a century ago. In his seminal theory, Einstein described how light travels in curved paths under the influence of a gravitational field. So massive objects like black holes, but also planets and stars, can act to bend light from a more distant object, effectively becoming a lens.
This means that if a planet or star in an intervening galaxy passes directly between the Earth and a more distant AGN, over a few years or so they act as a lens, focusing and intensifying the signal coming from near the black hole. This type of lensing, due to a single star, is termed microlensing. As the lensing object travels across the AGN, emitting regions are amplified to an extent that depends on their size, providing astronomers with valuable clues.
Bruce and his team believe they have already seen evidence for two microlensing events associated with AGN. These are well described by a simple model, displaying a single peak and a tenfold increase in brightness over several years. MIcrolensing in AGNs has been seen before, but only where the presence of the galaxy was already known. Now Bruce and his team are seeing the extreme changes in brightness that signifies the discovery of both previously unknown microlenses and AGNs.
Bruce says: "Every so often, nature lends astronomers a helping hand and we see a very rare event. It's remarkable that an unpredictable alignment of objects billions of light years away could help us probe the surroundings of black holes. In theory, microlensing could even let us see detail in accretion discs and the clouds in their vicinity. We really need to take advantage of these opportunities whenever they arise."
Read more at Science Daily
|Harvard researchers observed evidence of the transition of hydrogen to metallic hydrogen by squeezing a sample of liquid hydrogen between two diamond tips.|
One theory is that about halfway to Jupiter's core, the pressures and temperatures become so intense that the hydrogen that makes up 90 percent of the planet -- molecular gas on Earth -- looses hold of its electrons and begins behaving like a liquid metal. Oceans of liquid metallic hydrogen surrounding Jupiter's core would explain its powerful magnetic field.
But how and when does this transition from gas to liquid metal occur? How does it behave? Researchers hope that Juno will shed some light on this exotic state of hydrogen -- but one doesn't need to travel all the way to Jupiter to study it.
Four hundred million miles away, in a small, windowless room in the basement of Lyman Laboratory on Oxford Street in Cambridge, Massachusetts, there was, for a fraction of a fraction of a second, a small piece of Jupiter.
Earlier this year, in an experiment about five-feet long, Harvard University researchers say they observed evidence of the abrupt transition of hydrogen from liquid insulator to liquid metal. It is one of the first times such a transition has ever been observed in any experiment.
They published their research in Physical Review B.
"This is planetary science on the bench," said Mohamed Zaghoo, the NASA Earth & Space Science Fellow at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). "The question of how hydrogen transitions into a metallic state -- whether that is an abrupt transition or not -- has huge implications for planetary science. How hydrogen transitions inside Jupiter, for example, says a lot about the evolution, the temperature and the structure of these gas giants interiors."
In the experiment, Zaghoo, Ashkan Salamat, and senior author Isaac Silvera, the Thomas D. Cabot Professor of the Natural Sciences, recreated the extreme pressures and temperatures of Jupiter by squeezing a sample of hydrogen between two diamond tips, about 100 microns wide, and firing short bursts of lasers of increasing intensity to raise the temperature.
This experimental setup is significantly smaller and cheaper than other current techniques to generate metallic hydrogen, most of which rely on huge guns or lasers that generate shock waves to heat and pressurize hydrogen.
The transition of the liquid to metallic hydrogen happens too quickly for human eyes to observe and the sample lasts only a fraction of a second before it deteriorates. So, instead of watching the sample itself for evidence of the transition, the team watched lasers pointed at the sample. When the phase transition occurred, the lasers abruptly reflected.
"At some point, the hydrogen abruptly transitioned from an insulating, transparent state, like glass, to a shiny metallic state that reflected light, like copper, gold or any other metal," Zaghoo said. "Because this experiment, unlike shock wave experiments, isn't destructive, we could run the experiment continuously, doing measurements and monitoring for weeks and months to learn about the transition."
"This is the simplest and most fundamental atomic system, yet modern theory has large variances in predictions for the transition pressure," Silvera said. "Our observation serves as a crucial guide to modern theory."
The results represent a culmination of decades of research by the Silvera group. The data collected could begin to answer some of the fundamental questions about the origins of solar systems.
Metallic hydrogen also has important ramifications here on Earth, especially in energy and materials science.
"A lot of people are talking about the hydrogen economy because hydrogen is combustibly clean and it's very abundant," said Zaghoo. "If you can compress hydrogen into high density, it has a lot of energy compacted into it."
"As a rocket fuel, metallic hydrogen would revolutionize rocketry as propellant an order of magnitude more powerful than any known chemical," said Silvera. "This could cut down the time it takes to get to Mars from nine months to about two months, transforming prospects of human space endeavors."
Read more at Science Daily
|Skeletal myotubes grown for three weeks on gelatin hydrogel.|
First authors Archana Bettadapur and Gio C. Suh describe these muscles-on-a-chip in a new study published in Scientific Reports.
During normal embryonic development, skeletal muscles form when cells called myoblasts fuse to form muscle fibers, known as myotubes.
In past experiments, mouse myotubes have detached or delaminated from protein-coated plastic scaffolds after approximately one week and failed to thrive.
In this experiment, the researchers fabricated a gel scaffold from gelatin, a derivative of the naturally occurring muscle protein collagen, and achieved much better results. After three weeks, many of the mouse myotubes were still adhering to these gelatin chips, and they were longer, wider and more developed as a result.
The researchers anticipate that human myotubes would thrive equally well on gelatin chips. These new and improved "muscles-on-a-chip" could then be used to study human muscle development and disease, as well as provide a relevant testing ground for new potential drugs.
"Disease and disorders involving skeletal muscle -- ranging from severe muscular dystrophies to the gradual decrease in muscle mass with aging -- dramatically reduce the quality of life for millions of people," said McCain, assistant professor of biomedical engineering at the USC Viterbi School of Engineering, and stem cell biology and regenerative medicine at the Keck School of Medicine of USC. "By creating an inexpensive and accessible platform for studying skeletal muscle in the laboratory, we hope to enable research that will usher in new treatments for these patients."
McCain is already putting the gelatin chips into action as the winner of an Eli and Edythe Broad Innovation Awards in Stem Cell Biology and Regenerative Medicine at USC. The award provides $120,000 to McCain and her two collaborators: Justin Ichida, assistant professor of stem cell biology and regenerative medicine; and Dion Dickman, assistant professor of biological sciences at the USC Dornsife College of Letters, Arts and Sciences. In their project, they will use the gelatin chips for studying amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, which damages the intersections between motor nerve cells and muscle cells, called neuromuscular junctions (NMJs). McCain, Ichida and Dickman will use skin or blood cells from patients with ALS to generate and study NMJs on gelatin chips.
From Science Daily
"Observations of light emitted by water and by dust often go hand-in-hand. We usually interpret them as an insight into star-forming regions, with the illumination from young stars warming dust particles and water molecules until they start to glow. Now, thanks to the power of ALMA, we can -- for the first time -- separate out the emissions from the dust and water populations, and pinpoint their exact origins in the galaxy. The results are quite unexpected in that we've found that the water is located nowhere near the dusty stellar nurseries," explained Dr Gullberg, of the Centre for Extragalactic Astronomy, Durham University, UK.
The Spiderweb Galaxy is one of the most massive galaxies known. It lies 10 billion light-years away and is made up of dozens of star-forming galaxies in the process of merging together. The ALMA observations show that the light from the dust originates in the Spiderweb Galaxy itself. However, the light from the water is concentrated in two regions far to the east and west of the galaxy core.
Gullberg and her colleagues believe that the explanation lies with powerful jets of radio waves that are ejected from a supermassive black hole at the centre of the Spiderweb Galaxy. The radio jets compress clouds of gas along their path and heat up water molecules contained within the clouds until they emit radiation.
"Our results show how important it is to pinpoint the exact locations and origins for light in galaxies. We may also have new clues to the processes that trigger star formation in interstellar clouds," said Gullberg. "Stars are born out of cold, dense molecular gas. The regions in the Spiderweb where we've detected water are currently too hot for stars to form. But the interaction with the radio jets changes the composition of the gas clouds. When the molecules have cooled down again, it will be possible for the seeds of new stars to form. These "dew drop" regions could become the next stellar nurseries in this massive, complex galaxy."
The results will be presented at the National Astronomy Meeting 2016 in Nottingham by Dr Bitten Gullberg on Friday 1st July.
From Science Daily
Jun 30, 2016
|A smart new material reacts to light, can remember its shape as it folds and unfolds and can heal itself when damaged.|
This is the first time researchers have been able to combine several smart abilities, including shape memory behavior, light-activated movement and self-healing behavior, into one material. They have published their work in ACS Applied Materials & Interfaces.
The work is led by Michael Kessler, professor and Berry Family director and in the WSU School of Mechanical and Materials Engineering (MME), and Yuzhan Li, MME staff scientist, in collaboration with Orlando Rios, a researcher at Oak Ridge National Laboratory.
Adding functional versatility
Smart materials that can react to external stimuli, like light or heat, have been an interesting novelty and look almost magical as they mysteriously fold and unfold themselves. They have a variety of potential applications, such as for actuators, drug delivery systems and self-assembling devices. For instance, smart materials could change shape to unfold a solar panel on a space satellite without need of a battery-powered mechanical device.
But smart materials haven't come into widespread use because they are difficult to make and often can only perform one function at a time. Researchers also have struggled to reprocess the material so its special properties can continually repeat themselves.
The WSU research team developed a material that allows multiple functions at once with potential to add more.
Fold and unfold, remember and heal
The team worked with a class of long-chain molecules, called liquid crystalline networks (LCNs), which provide order in one direction and give material unique properties. The researchers took advantage of the way the material changes in response to heat to induce a unique three-way shape shifting behavior. They added groups of atoms that react to polarized light and used dynamic chemical bonds to improve the material's reprocessing abilities.
"We knew these different technologies worked independently and tried to combine them in a way that would be compatible,'' said Kessler.
The resulting material reacts to light, can remember its shape as it folds and unfolds and can heal itself when damaged. For instance, a razor blade scratch in the material can be fixed by applying ultraviolet light. The material's movements can be preprogrammed and its properties tailored.
The Oak Ridge National Laboratory researchers used facilities at their Center for Nanophase Materials Sciences to study the mechanisms responsible for the material's unique abilities.
Read more at Science Daily
|a) Dolmen da Orca, a typical dolmenic structure in western Iberia; b) view of the passage and entrance while standing within the dolmens' chamber: the 'window of visibility'; c) Orca de Santo Tisco, a dolmen with a much smaller passage or corridor.|
The team's idea is to investigate how a simple aperture, for example an opening or doorway, affects the observation of slightly fainter stars. They focus this study on passage graves, which are a type of megalithic tomb composed of a chamber of large interlocking stones and a long narrow entrance. These spaces are thought to have been sacred, and the sites may have been used for rites of passage, where the initiate would spend the night inside the tomb, with no natural light apart from that shining down the narrow entrance lined with the remains of the tribe's ancestors.
These structures could therefore have been the first astronomical tools to support the watching of the skies, millennia before telescopes were invented. Kieran Simcox, a student at Nottingham Trent University, and leading the project, comments: "It is quite a surprise that no one has thoroughly investigated how for example the colour of the night sky impacts on what can be seen with the naked eye."
The project targets how the human eye, without the aid of any telescopic device, can see stars given sky brightness and colour. The team intend to apply these ideas to the case of passage graves, such as the 6,000 year old Seven-Stone Antas in central Portugal. Dr Fabio Silva, of the University of Wales Trinity Saint David, explains that, "the orientations of the tombs may be in alignment with Aldebaran, the brightest star in the constellation of Taurus. To accurately time the first appearance of this star in the season, it is vital to be able to detect stars during twilight."
The first sighting in the year of a star after its long absence from the night sky might have been used as a seasonal marker, and could indicate for example the start of a migration to summer grazing grounds. The timing of this could have been seen as secret knowledge or foresight, only obtained after a night spent in contact with the ancestors in the depths of a passage grave, since the star may not have been observable from outside. However, the team suggest it could actually have been the result of the ability of the human eye to spot stars in such twilight conditions, given the small entrance passages of the tombs.
Read more at Science Daily
|The green galaxy is caught in the act of transforming from blue to red as its gas supply runs out.|
Using the state-of-the-art EAGLE simulations, the researchers modelled how both the ages of stars in galaxies and what those stars are made from translate into the colour of light that they produce.
The research team said its simulations showed that colours of galaxies can also help diagnose how they evolve.
While red and blue galaxies are relatively common, rare green galaxies are likely to be at an important stage in their evolution, when they are rapidly turning from blue -- when new stars and planets are being born -- to red as stars begin to burn themselves out.
The research funded by the Science and Technology Facilities Council (STFC) and the European Research Council (ERC) is being presented today (Thursday 30 June) at the Royal Astronomical Society's National Astronomy Meeting in Nottingham, UK.
Lead researcher James Trayford, PhD student in the ICC at Durham University, said: "Galaxies emit a healthy blue glow while new stars and planets are being born. However, if the formation of stars is halted galaxies turn red as stars begin to age and die.
"In the real Universe we see many blue and red galaxies, but these intermediate 'green' galaxies are more rare.
"This suggests that the few green galaxies we catch are likely to be at a critical stage in their evolution; rapidly turning from blue to red."
Because stars form from dense gas, a powerful process is needed to rapidly destroy their gas supply and cause such dramatic changes in colour, the research found.
James added: "In a recent study we followed simulated galaxies as they changed colour, and investigated what processes caused them to change.
"We typically find that smaller green galaxies are being violently tossed around by the gravitational pull of a massive neighbour, causing their gas supply to be stripped away.
"Meanwhile, bigger green galaxies may self-destruct as immense explosions triggered by super-massive black holes at their centres can blow dense gas away."
However, the research found that there was some hope for green galaxies as a lucky few might absorb a fresh supply of gas from their surroundings.
This can revive the formation of stars and planets, and restore galaxies to a healthy blue state.
James said: "By using simulations to study how galaxy colours change, we can speed up the process of galaxy evolution from the billions of years it takes in the real Universe to just a matter of days in a computer.
Read more at Science Daily
|This image combines an image taken with Hubble Space Telescope in the optical (taken in spring 2014) and observat ions of its auroras in the ultraviolet, taken in 2016.|
Jupiter, the largest planet in the Solar System, is best known for its colourful storms, the most famous being the Great Red Spot. Now astronomers have focused on another beautiful feature of the planet, using the ultraviolet capabilities of the NASA/ESA Hubble Space Telescope.
The extraordinary vivid glows shown in the new observations are known as auroras. They are created when high energy particles enter a planet's atmosphere near its magnetic poles and collide with atoms of gas. As well as producing beautiful images, this programme aims to determine how various components of Jupiter's auroras respond to different conditions in the solar wind, a stream of charged particles ejected from the Sun.
This observation programme is perfectly timed as NASA's Juno spacecraft is currently in the solar wind near Jupiter and will enter the orbit of the planet in early July 2016. While Hubble is observing and measuring the auroras on Jupiter, Juno is measuring the properties of the solar wind itself; a perfect collaboration between a telescope and a space probe.
"These auroras are very dramatic and among the most active I have ever seen," says Jonathan Nichols from the University of Leicester, UK, and principal investigator of the study. "It almost seems as if Jupiter is throwing a firework party for the imminent arrival of Juno."
To highlight changes in the auroras Hubble is observing Jupiter daily for around one month. Using this series of images it is possible for scientists to create videos that demonstrate the movement of the vivid auroras, which cover areas bigger than the Earth.
Not only are the auroras huge, they are also hundreds of times more energetic than auroras on Earth. And, unlike those on Earth, they never cease. Whilst on Earth the most intense auroras are caused by solar storms -- when charged particles rain down on the upper atmosphere, excite gases, and cause them to glow red, green and purple -- Jupiter has an additional source for its auroras.
The strong magnetic field of the gas giant grabs charged particles from its surroundings. This includes not only the charged particles within the solar wind but also the particles thrown into space by its orbiting moon Io, known for its numerous and large volcanos.
Read more at Science Daily
Jun 29, 2016
|The study indicated that pigs with more proactive personality types produced grunts at a higher rate than the more reactive animals.|
Scientists specialising in animal behaviour and welfare devised an experiment to investigate the relationship between personality and the rate of grunting in pigs. They also examined the effect different quality living conditions had on these vocalisations.
Findings from the study, carried out by researchers from the University of Lincoln, UK, and Queens University Belfast, are published in the Royal Society journal Open Science.
The study involved 72 male and female juvenile pigs. Half were housed in spacious 'enriched' pens with straw bedding, while the other half were kept in more compact 'barren' pens with partially slatted concrete floors, which adhered to UK welfare requirements.
To get a measure of the pigs' personalities, the researchers conducted two tests: a social isolation test and a novel object test. Each pig spent three minutes in social isolation, and five minutes in a pen with a large white bucket or an orange traffic cone they had not previously encountered. Their behaviour, including vocalisations, were observed. These tests were repeated two weeks later, allowing the researchers to determine if the pigs' responses were repeatable -- the defining characteristic of personality (also known as 'coping style' in animals).
They also recorded the frequency of grunts they made by counting the number of grunts produced per minute of the test, and investigated the effect different quality environments had on the sounds made.
The study indicated that pigs with more proactive personality types produced grunts at a higher rate than the more reactive animals. The study also found that male pigs (but not females) kept in the lower-quality conditions made fewer grunts compared with those housed in the enriched environment, suggesting greater susceptibility among male pigs to environmental factors.
The results add to evidence that acoustic signalling indicates personality in pigs. This may have had far reaching consequences in shaping the evolution of social behaviours, the researchers believe. The findings also suggest personality needs to be kept in mind when using vocalisation as a measure of the animals' welfare status.
Principal investigator, Dr Lisa Collins, a specialist in animal health, behaviour and welfare epidemiology in the School of Life Sciences at the University of Lincoln, said: "The domestic pig is a highly social and vocal species which uses acoustic signals in a variety of ways; maintaining contact with other group members while foraging, parent-offspring communication, or to signal if they are distressed.
"The sounds they make convey a wide range of information such as the emotional, motivational and physiological state of the animal. For example, squeals are produced when pigs feel fear, and may be either alerting others to their situation or offering assurance. Grunts occur in all contexts, but are typical of foraging to let other members of the group know where they are."
Read more at Science Daily
|Researchers at the University of Pennsylvania developed a simple mathematical model that describes how animal social networks arise. The model recapitulated important qualities of observed social networks of several species, including spotted hyenas.|
In a newly published study in the journal Nature Communications, two biologists from the University of Pennsylvania have developed a mathematical model of the way social networks arise in animal populations. Their model considers the likelihood that a newborn forms connections with its mother's connections or other individuals not connected to its mother, with the assumption that an individual is more likely to connect with those connected with its mother.
Though relatively simple, their model generated networks that faithfully recapitulated important properties of networks observed in field-collected data from four very different animal populations: spotted hyenas, sleep lizards, rock hyrax and bottlenose dolphins.
The work was conducted by Amiyaal Ilany, a postdoctoral researcher, and Erol Akçay, an assistant professor, both of Penn's Department of Biology in the School of Arts & Sciences.
"What we show," said Akçay, "is that we can fit this simple model to real-life networks and capture their degree distribution, or how connected everyone is, and, more strikingly, we can also capture the distribution of what's known as the clustering coefficient, which measures how cliquish the population is."
For as long as biologists have been studying animal populations, they've made observations about social relationships in the group. But it has only been in the last decade or so that social-network analysis has come to the fore in generating an understanding of the dynamics of these networks.
"There has been an explosion of studies in the last 10 years or more," Ilany said, "showing that social networks have implications for longevity or disease transmission or reproductive success. It's become quite clear that social network structure is important."
Yet these analyses, which have used field observations to construct a social network, have not provided researchers a more general picture of how networks emerge.
"What we saw as missing is some theory of how you actually get the social structure that we observe," Ilany said.
To address this gap on the theoretical side of network analysis, Akçay and Ilany envisioned a simple, straightforward process by which individual animals can either make or lose social connections.
"The model says, if someone enters into a network, they have two ways of making connections," Akçay explained. "Assuming the individual is a newborn, they will make a connection with their mother and their mother's connections, and they could also become connected to random individuals to whom their mother might not be connected."
Using only these two parameters, corresponding to the probabilities of each type of connection, and assuming a finite population in which individuals entered by being born and left by dying, they found that the model captured essential properties of animal social networks observed in the wild. This included a tendency for some individuals to be highly connected and others less so and a tendency to form clusters, or "cliques." This was true when the researchers ran data through the model from rock hyrax, the species Ilany studied for his Ph.D., as well as data on spotted hyenas, bottlenose dolphins and sleepy lizards.
"Alternative models that we considered," Akçay said, "like the theory that individuals connect based on shared traits or interests, captured the degree distribution but didn't generate enough clustering. There's something special about the idea that I'm more likely to connect with you if you're connected with someone I already know. That's what generates this cliquishness we see in the model."
While some researchers have postulated that social status might be genetically heritable, this work suggests that a newborn could "inherit" its mother's social status non-genetically, simply by copying its mother's social network. Akçay and Ilany term this "social inheritance."
"We show that, if I just copy my mother, I become very similar to her socially," Ilany said. "It's still possible that there is genetic inheritance of social traits, but part of that inheritance can be explained by this simple social process."
The biologists noted that the behavioral processes that lead to the formation of connections may look very different in different species. In many primates, for example, individuals of a group take a special interest in newborns, even offering the mother grooming in exchange for "baby time." In other species, the acquisition of social connections might be more passive, with young individuals simply developing relationships with their mother's connections because they remain in close proximity to their mother as they grow.
As a result, the model may be stronger for mammals, which are physically dependent on their mother, than for other species such as insects. The work also has the potential to inform how human social networks formed historically.
"If you want to think about how humans evolved to be this super cooperative species," Akçay said, "the fine-scale social structure of a group has implications for how that process might have worked."
Read more at Science Daily
|The London Underground Mosquito (Culex pipiens molestus) has been found in underground systems around the world. It is believed to have evolved from the common house mosquito through a subterranean population.|
A growing number of examples show that humans not only contribute to the extinction of species but also drive evolution, and in some cases the emergence of entirely new species. This can take place through mechanisms such as accidental introductions, domestication of animals and crops, unnatural selection due to hunting, or the emergence of novel ecosystems such as the urban environment.
Although tempting to conclude that human activities thus benefit as well as deplete global biodiversity, the authors stress that extinct wild species cannot simply be replaced with newly evolved ones, and that nature conservation remains just as urgent.
"The prospect of 'artificially' gaining novel species through human activities is unlikely to elicit the feeling that it can offset losses of 'natural' species. Indeed, many people might find the prospect of an artificially biodiverse world just as daunting as an artificially impoverished one" says lead author and Postdoc Joseph Bull from the Center for Macroecology, Evolution and Climate at the University of Copenhagen.
The study which was carried out in collaboration with the University of Queensland was published today in Proceedings of Royal Society B. It highlights numerous examples of how human activities influence species' evolution. For instance: as the common house mosquito adapted to the environment of the underground railway system in London, it established a subterranean population. Now named the 'London Underground mosquito', it can no longer interbreed with its above ground counterpart and is effectively thought to be a new species.
"We also see examples of domestication resulting in new species. According to a recent study, at least six of the world's 40 most important agricultural crops are considered entirely new" explains Joseph Bull.
Furthermore, unnatural selection due to hunting can lead to new traits emerging in animals, which can eventually lead to new species, and deliberate or accidental relocation of species can lead to hybridization with other species. Due to the latter, more new plant species in Europe have appeared than are documented to have gone extinct over the last three centuries.
Although it is not possible to quantify exactly how many speciation events have been caused through human activities, the impact is potentially considerable, the study states.
"In this context, 'number of species' becomes a deeply unsatisfactory measure of conservation trends, because it does not reflect many important aspects of biodiversity. Achieving a neutral net outcome for species numbers cannot be considered acceptable if weighing wild fauna against relatively homogenous domesticated species. However, considering speciation alongside extinction may well prove important in developing a better understanding of our impact upon global biodiversity. We call for a discussion about what we, as a society, actually want to conserve about nature" says Associate Professor Martine Maron from the University of Queensland.
Read more at Science Daily
A team of researchers at Beijing Institute of Technology and Zhejiang University in China propose another question, "Where in the droplet does the crystallization of water or liquid silicon begin?" The team explains their findings this week in The Journal of Chemical Physics, from AIP Publishing. This is an interesting problem and one that is crucial to understanding the crystallization mechanism of nanoscale tetrahedral liquid drops like water and silicon.
In their work, they used computer simulation, to find that the ripple-like density waves are markedly excited before crystallization of liquid silicon drops and films due to the volume expansion in a confined environment. The ripple-like density fluctuations create waves capable of promoting nucleation, eventually resulting in a ripple-like distribution of nucleation probability in drops and films. These results suggest that the freezing of nanoscale water or silicon liquid drops is initiated at a number of different distances from the center of the droplet, providing new insights on a long-standing dispute in the field of material and chemical physics.
The research team employed a molecular dynamics simulation to investigate the freezing of nanoscale silicon drops and films, a method widely used for the investigations of microscopic thermodynamic and dynamic process. In computer simulations of crystallization events, the short simulation time makes it difficult to observe. To address this issue some special simulation methods, namely, the rare event sampling algorithms, were proposed. But these methods inevitably drop some high probability regions of nucleation in the trajectory sampling starting from a single configuration, so the team employed brute-force simulation and sampled massive and independent crystallization processes. "Although the method is 'brute,' it can faithfully represent the distribution of nuclei," explained Yongjun Lü, a physicist at Beijing Institute of Technology and Zhejiang University. "This is why we were able to observe the ripple-like distribution of nucleation probability while it is absent in other studies."
A challenge for the team was the great calculation costs. To achieve the credible probability distributions of nucleation in drops and films requires massive statistical sampling, requiring more than 6 months of CPU time.
The implications of this research are far-reaching. "We can extend the present results to all the tetrahedral liquids including water due to their similarity in molecular structure," Lü said. "It suggests that the surface environment does not play a decisive role in the formation of ice and snow as expected. The density fluctuations inside drops result in that the possible freezing regions cover the middle and the surface regions, depending on the drop size. The freezing from the surface or from within may be random."
Read more at Science Daily
Jun 28, 2016
|Approximately 500,000 years after the major natural disaster at the boundary between the Permian and the Triassic another event altered the vegetation fundamentally and for longer.|
There have been several mass extinctions in the history of Earth. One of the largest known disasters occurred around 252 million years ago at the boundary between the Permian and the Triassic. Almost all sea-dwelling species and two thirds of all reptiles and amphibians died out. Although there were also brief declines in diversity in the plant world, they recovered in the space of a few thousand years, which meant that similar conditions to before prevailed again.
Change in flora within a millennia
Researchers from the Institute and Museum of Paleontology at the University of Zurich have now discovered another previously unknown ecological crisis on a similar scale in the Lower Triassic. The team headed by Peter A. Hochuli and Hugo Bucher revealed that another event altered the vegetation fundamentally and for longer approximately 500,000 years after the major natural disaster at the boundary between the Permian and the Triassic.
The scientists studied sediments towering over 400 meters high from North-Eastern Greenland. Carbon isotope curves suggest that the prevalent seed ferns and conifers were replaced by spore plants in the space of a few millennia. To this day, certain spore plants like ferns are still famous for their ability to survive hostile conditions better than more highly developed plants.
Catastrophic ecological upheaval changes plant world
Until now, it was assumed that the environment gradually recovered during the Lower Triassic 252.4 to 247.8 million years ago. "The drastic, simultaneous changes in flora and the composition of the carbon isotopes indicate that the actual upheaval in the vegetation didn't take place until the Lower Triassic, i.e. around 500,000 years later than previously assumed," explains Hochuli.
The researchers didn't just observe the mass death of vegetation in Greenland; they already discovered the first indications of this floral shift a few years ago in sediment samples from Pakistan. Moreover, the latest datings of volcanic ash by Australian scientists show that the most significant change in the plant world did not happen until a few millennia after the Permian/Triassic boundary. During this period, the indigenous glossopteris seed plant group died out, an event that had previously been dated back to the Permian. Thanks to these findings, the sediment sequences of the supercontinent Gondwana in the southern hemisphere now need to be reinterpreted.
Read more at Science Daily
Makemake orbits the sun at an average distance of around 45 AU (astronomical units, where 1 AU is the average distance the Earth orbits the sun), so to zoom in on its location, the most powerful space telescope was needed to understand more of its nature. Hubble uncovered the landmark find in April, but before then, there was little evidence that Makemake possessed its own natural satellite and if it didn't have a moon, astronomers wanted to understand why. But that changed when observations by Hubble's Wide Field Camera 3 were analyzed and an extremely dark moon emerged as a faint point of light very close to the dwarf planet. The Kuiper belt object (KBO) was discovered in 2005 by a Caltech team led by astronomer Mike Brown.
"Makemake's moon proves that there are still wild things waiting to be discovered, even in places people have already looked," said astronomer Alex Parker, of the Southwest Research Institute (SwRI), who is credited with the discovery of the moon. "Makemake's moon -- nicknamed MK2 -- is very dark, 1,300 times fainter than the dwarf planet."
Parker's research has now been published in the June 27 issue of Astrophysical Journal Letters.
|The moon over Makemake is faint but visible on the left, but completely lost in the glare of the parent dwarf on the right.|
Known to posses a shell of methane ice, Makemake measures around 870 miles across. It is estimated that MK2 is approximately 100 miles wide.
"With a moon, we can calculate Makemake's mass and density," said Parker. "We can contrast the orbits and properties of the parent dwarf and its moon, to understand the origin and history of the system. We can compare Makemake and its moon to other systems, and broaden our understanding of the processes that shaped the evolution of our solar system."
Read more at Discovery News
This research could help shed light on currently hidden aspects of the universe, from the hearts of neutron stars to the very first moments of the universe after, the Big Bang researchers said.
Quantum mechanics suggests that the universe is a fuzzy, surreal place at its smallest levels. For instance, atoms and other particles can exist in states of flux known as superpositions, where they can seemingly each spin in opposite directions simultaneously, and they can also get entangled — meaning they can influence each other instantaneously no matter how far apart they are separated. Quantum mechanics also suggests that pairs of virtual particles, each consisting of a particle and its antiparticle, can wink in and out of seemingly empty vacuum and influence their surroundings.
Quantum mechanics underlies the standard model of particle physics, which is currently the best explanation for how all the known elementary particles, such as electrons and protons, behave. However, there are still many open questions regarding the standard model of particle physics, such as whether or not it can help explain cosmic mysteries such as dark matter and dark energy — both of which have not been directly detected by astronomers, but are inferred based on their gravitational effects.
The interactions between elementary particles are often described with what is known as gauge theories. However, the real-time dynamics of particles in gauge theories are extremely difficult for conventional computers to compute, except in the simplest of cases. As a result, scientists have instead turned to experimental devices known as quantum computers.
"Our work is a first step towards developing dedicated tools that can help us to gain a better understanding of the fundamental interactions between the elementary constituents in nature," study co-lead author Christine Muschik told Live Science. Muschik is a theoretical physicist at the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences in Innsbruck, Austria.
Whereas classical computers represent data as ones and zeroes — binary digits known as "bits," symbolized by flicking switch-like transistors either on or off — quantum computers use quantum bits, or qubits, that are in superpositions — meaning that they are on and off at the same time. This enables a qubit to carry out two calculations simultaneously. In principle, quantum computers could work much faster than regular computers at solving certain problems because the quantum machines can analyze every possible solution at once.
In their new study, scientists built a quantum computer using four electromagnetically trapped calcium ions. They controlled and manipulated these four qubits with laser pulses.
The researchers had their quantum computer simulate the appearance and disappearance of virtual particles in a vacuum, with pairs of qubits representing pairs of virtual particles — specifically, electrons and positrons, the positively charged antimatter counterparts of electrons. Laser pulses helped simulate how powerful electromagnetic fields in a vacuum can generate virtual particles, the scientists said.
"This is one of the most complex experiments that has ever been carried out in a trapped-ion quantum computer," study co-author Rainer Blatt, an experimental physicist at the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences in Innsbruck, Austria, said in a statement.
This work shows that quantum computers can simulate high-energy physics — showing how particles might behave at energy levels that are much too high to be easily generated on Earth. "The field of experimental quantum computing is growing very fast, and many people ask the question, What is a small-scale quantum computer good for?" study co-lead author Esteban Martinez, an experimental physicist at the University of Innsbruck in Austria, told Live Science. "Unlike other applications, you don't need millions of quantum bits to do these simulations — tens might be enough to tackle problems that we cannot yet attack using classical approaches."
The problem the researchers had their quantum simulator analyze was simple enough for classical computers to compute, which showed that the quantum simulator's results matched predictions with great accuracy. This suggests that quantum simulators could be used on more complex gauge-theory problems in the future, and the machines could even see new phenomena.
"Our proof-of-principle experiment represents a first step toward the long-term goal of developing future generations of quantum simulators that will be able to address questions that cannot be answered otherwise," Muschik said.
Read more at Discovery News
|A 99-million-year-old wing from a toothed bird preserved in amber. The specimen includes a claw and a pale spot on the plumage.|
The 99-million-year-old wings -- nicknamed "angel wings" and "Rose" by the researchers -- include the first examples of hair follicles and feather arrangements from the Cretaceous Period, according to the paper, published in the journal Nature Communications.
|The "angel wing," under a compound microscope, show pigment banding in feather barbules, and the outline of the Cretaceous bird's claw.|
|An enantiornithine is partially ensnared by tree resin, based on the "angel wing" specimen.|
McKellar, lead author Lida Xing and their colleagues found the fossils at a site in the Kachin Province of Myanmar. They examined the structure and arrangement of the bones and feathers in the fossils using techniques such as synchrotron X-ray micro CT scanning.
Read more at Discovery News
|An image of Vulpecula OB1, a birthplace of massive stars, captured by the Herschel Space Observatory.|
The space-based telescope was built to detect radiation that had been invisible to other telescopes at the time. That ability not only allowed it to fulfill its major objective of discovering how the first galaxies formed and evolved, but also made it an excellent choice for detecting dust and gas clouds that lead to the formation of new stars. Although its mission ended in 2013, scientists are still analyzing the wealth of data that Herschel collected over its four years of operation, uncovering stunning photographs such as this one.
Located in the constellation Vulpecula, or Little Fox, the region (pictured here in infrared wavelengths) births some of the biggest stars in the galaxy. These colossal O- and B-type stars have much more mass than the sun — up to 16 times more for B stars and up to a staggering 100 times more for O stars — and their lives are significantly shorter for it. They last only a few million years before exhausting their fuel, collapsing and exploding as supernovas, triggering the next batch of stellar births in the region. Because they are so short-lived, the presence of a large number of them in one place signals ongoing star formation.
But what is truly surprising about this image is that the filaments of glowing interstellar gas seen here as red and orange threads are part of a vast, structured web that stretches across all of the galaxy's star-forming regions, NASA officials said in a statement. It was obtained via the Herschel Infrared Galactic Plane Survey, which mapped the inner Milky Way in five different infrared wavelengths.
From Discovery News
Jun 27, 2016
The new technique uses both laser light and microwaves to precisely control the switching of selected individual qubits from one quantum state to another without altering the states of the other atoms in the cubic array. The new technique demonstrates the potential use of atoms as the building blocks of circuits in future quantum computers.
The scientists invented an innovative way to arrange and precisely control the qubits, which are necessary for doing calculations in a quantum computer. "Our paper demonstrates that this novel approach is a precise, accurate, and efficient way to control large ensembles of qubits for quantum computing," Weiss said.
The paper in Science describes the new technique, which Weiss's team plans to continue developing further. The achievement also is expected to be useful to scientists pursuing other approaches to building a quantum computer, including those based on other atoms, on ions, or on atom-like systems in 1 or 2 dimensions. "If this technique is adopted in those other geometries, they would also get this robustness," Weiss said.
To corral their quantum atoms into an orderly 3-D pattern for their experiments, the team constructed a lattice made by beams of light to trap and hold the atoms in a cubic arrangement of five stacked planes -- like a sandwich made with five slices of bread -- each with room for 25 equally spaced atoms. The arrangement forms a cube with an orderly pattern of individual locations for 125 atoms. The scientists filled some of the possible locations with qubits consisting of neutral cesium atoms -- those without a positive or a negative charge. Unlike the bits in a classical computer, which typically are either zeros or ones, each of the qubits in the Weiss team's experiment has the difficult-to-imagine ability to be in more than one state at the same time -- a central feature of quantum mechanics called quantum superposition.
Weiss and his team then use another kind of light tool -- crossed beams of laser light -- to target individual atoms in the lattice. The focus of these two laser beams, called "addressing" beams, on a targeted atom shifts some of that atom's energy levels by about twice as much as it does for those of any of the other atoms in the array, including those that were in the path of one of the addressing beams on its way to the target. When the scientists then bathe the whole array with a uniform wash of microwaves, the state of the atom with the shifted energy levels is changed, while the states of all the other atoms are not.
"We have set more qubits into different, precise quantum superpositions at the same time than in any previous experimental system," Weiss said. The scientists also designed their system to be very insensitive to the exact details of the alignments or the power of those light beams they use -- which Weiss said is a good thing because "you don't want to be dependent upon exactly what the intensity of the light is or exactly what the alignment is."
One of the ways that the scientists demonstrated their ability to change the quantum state of individual atoms was by changing the states of selected atoms in three of the stacked planes within the cubic array in order to draw the letters P, S, and U -- the letters that represent Penn State University. "We changed the quantum superposition of the PSU atoms to be different from the quantum superposition of the other atoms in the array," Weiss said. "We have a pretty high-fidelity system. We can do targeted selections with a reliability of about 99.7%, and we have a plan for making that more like 99.99%."
Read more at Science Daily
Using the information contained within the shells of tiny animals known as foraminifera, the researchers, led by the University of Cambridge, looked at the characteristics of the seawater in the Atlantic Ocean during the last ice age, including its ability to store carbon. Since atmospheric CO2 levels during the period were about a third lower than those of the pre-industrial atmosphere, the researchers were attempting to find if the extra carbon not present in the atmosphere was stored in the deep ocean instead.
They found that the deep ocean circulated at a much slower rate at the peak of the last ice age than had previously been suggested, which is one of the reasons why it was able to store much more carbon for much longer periods. That carbon was accumulated as organisms from the surface ocean died and sank into the deep ocean where their bodies dissolved, releasing carbon that was in effect 'trapped' there for thousands of years. Their results are reported in two separate papers in Nature Communications.
The ability to reconstruct past climate change is an important part of understanding why the climate of today behaves the way it does. It also helps to predict how the planet might respond to changes made by humans, such as the continuing emission of large quantities of CO2 into the atmosphere.
The world's oceans work like a giant conveyor belt, transporting heat, nutrients and gases around the globe. In today's oceans, warmer waters travel northwards along currents such as the Gulf Stream from the equatorial regions towards the pole, becoming saltier, colder and denser as they go, causing them to sink to the bottom. These deep waters flow into the ocean basins, eventually ending up in the Southern Ocean or the North Pacific Ocean. A complete loop can take as long as 1000 years.
"During the period we're looking at, large amounts of carbon were likely transported from the surface ocean to the deep ocean by organisms as they died, sunk and dissolved," said Emma Freeman, the lead author of one of the papers. "This process released the carbon the organisms contained into the deep ocean waters, where it was trapped for thousands of years, due to the very slow circulation."
Freeman and her co-authors used radiocarbon dating, a technique that is more commonly used by archaeologists, in order to determine how old the water was in different parts of the ocean. Using the radiocarbon information from tiny shells of foraminifera, they found that carbon was stored in the slowly-circulating deep ocean.
In a separate study led by Jake Howe, also from Cambridge's Department of Earth Sciences, researchers studied the neodymium isotopes contained in the foraminifera shells, a method which works like a dye tracer, and came to a similar conclusion about the amount of carbon the ocean was able to store.
"We found that during the peak of the last ice age, the deep Atlantic Ocean was filled not just with southern-sourced waters as previously thought, but with northern-sourced waters as well," said Howe.
What was previously interpreted to be a layer of southern-sourced water in the deep Atlantic during the last ice age was in fact shown to be a mixture of slowly circulating northern- and southern-sourced waters with a large amount of carbon stored in it.
Read more at Science Daily
The amplitude and frequency of these waves could reveal the initial mass of the seeds from which the first black holes grew since they were formed 13 billion years ago and provide further clues about what caused them and where they formed, the researchers said.
The research is being presented today (Monday, June 27, 2016) at the Royal Astronomical Society's National Astronomy Meeting in Nottingham, UK. It was funded by the Science and Technology Facilities Council, the European Research Council and the Belgian Interuniversity Attraction Poles Programme.
The study combined simulations from the EAGLE project -- which aims to create a realistic simulation of the known Universe inside a computer -- with a model to calculate gravitational wave signals.
Two detections of gravitational waves caused by collisions between supermassive black holes should be possible each year using space-based instruments such as the Evolved Laser Interferometer Space Antenna (eLISA) detector that is due to launch in 2034, the researchers said.
In February the international LIGO and Virgo collaborations announced that they had detected gravitational waves for the first time using ground-based instruments and in June reported a second detection.
As eLISA will be in space -- and will be at least 250,000 times larger than detectors on Earth -- it should be able to detect the much lower frequency gravitational waves caused by collisions between supermassive black holes that are up to a million times the mass of our sun.
Current theories suggest that the seeds of these black holes were the result of either the growth and collapse of the first generation of stars in the Universe; collisions between stars in dense stellar clusters; or the direct collapse of extremely massive stars in the early Universe.
As each of these theories predicts different initial masses for the seeds of supermassive black hole seeds, the collisions would produce different gravitational wave signals.
This means that the potential detections by eLISA could help pinpoint the mechanism that helped create supermassive black holes and when in the history of the Universe they formed.
Lead author Jaime Salcido, PhD student in Durham University's Institute for Computational Cosmology, said: "Understanding more about gravitational waves means that we can study the Universe in an entirely different way.
"These waves are caused by massive collisions between objects with a mass far greater than our sun.
"By combining the detection of gravitational waves with simulations we could ultimately work out when and how the first seeds of supermassive black holes formed."
Co- author Professor Richard Bower, of Durham University's Institute for Computational Cosmology, added: "Black holes are fundamental to galaxy formation and are thought to sit at the centre of most galaxies, including our very own Milky Way.
"Discovering how they came to be where they are is one of the unsolved problems of cosmology and astronomy.
"Our research has shown how space based detectors will provide new insights into the nature of supermassive black holes."
Gravitational waves were first predicted 100 years ago by Albert Einstein as part of his Theory of General Relativity.
The waves are concentric ripples caused by violent events in the Universe that squeeze and stretch the fabric of space time but most are so weak they cannot be detected.
LIGO detected gravitational waves using ground-based instruments, called interferometers, that use laser beams to pick up subtle disturbances caused by the waves.
Read more at Science Daily
|Bones from the 37,000 year old Deep Skull from Niah Cave in Sarawak.|
The Deep Skull was also likely to have been an older woman, rather than a teenage boy.
The research, led by UNSW Australia Associate Professor Darren Curnoe, represents the most detailed investigation of the ancient cranium specimen since it was found in Niah Cave in Sarawak in 1958.
"Our analysis overturns long-held views about the early history of this region," says Associate Professor Curnoe, Director of the UNSW Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA).
"We've found that these very ancient remains most closely resemble some of the Indigenous people of Borneo today, with their delicately built features and small body size, rather than Indigenous people from Australia."
The study, by Curnoe and researchers from the Sarawak Museum Department and Griffith University, is published in the journal Frontiers in Ecology and Evolution.
The Deep Skull was discovered by Tom Harrisson of the Sarawak Museum during excavations at the West Mouth of the great Niah Cave complex and was analysed by prominent British anthropologist Don Brothwell.
In 1960, Brothwell concluded the Deep Skull belonged to an adolescent male and represented a population of early modern humans closely related, or even ancestral, to Indigenous Australians, particularly Tasmanians.
"Brothwell's ideas have been highly influential and stood largely untested, so we wanted to see whether they might be correct after almost six decades," says Curnoe.
"Our study challenges many of these old ideas. It shows the Deep Skull is from a middle-aged female rather than a teenage boy, and has few similarities to Indigenous Australians. Instead, it more closely resembles people today from more northerly parts of South-East Asia."
Ipoi Datan, Director of the Sarawak Museum Department says: "It is exciting to think that after almost 60 years there's still a lot to learn from the Deep Skull -- so many secrets still to be revealed.
"Our discovery that the remains might well be the ancestors of Indigenous Bornean people is a game changer for the prehistory of South-East Asia."
The Deep Skull has also been a key fossil in the development of the so-called "two-layer" hypothesis in which South-East Asia is thought to have been initially settled by people related to Indigenous Australians and New Guineans, who were then replaced by farmers from southern China a few thousand years ago.
The new study challenges this view by showing that -- in Borneo at least -- the earliest people to inhabit the island were much more like Indigenous people living there today rather than Indigenous Australians, and suggests long continuity through time.
It also suggests that at least some of the Indigenous people of Borneo were not replaced by migrating farmers, but instead adopted the new farming culture when it arrived around 3,000 years ago.
Read more at Science Daily
Remains of the giant wooly mammal, believed to be some 14,000 years old, were discovered by chance in December near Mexico City while drainage pipes were being installed in the village of Tultepec.
Archaeologists have been working at the site since April, and they hope to complete their work in the next few days.
Luis Cordoba, an archaeologist with the National Institute of Anthropology and History, said the remains of more than fifty mammoths have been discovered in the area around the capital, where in pre-historic times there was a shallow saltwater lake where the heavy creatures often got stuck.
The lake was also very good for preserving the remains.
Other mammoth remains have been found in the Tultepec area, "but this is the first time that they can be studied because in general people do not report the finds in time," Cordoba said.
When alive, the mammoth was 3.5 meters high, five meters long, weighed around five tonnes, and was between the ages of 20 and 25.
The Tultepec mammoth, which is about three-quarters complete and well preserved, still has tusks attached to its skull.
However the remaining fossils "do not maintain an anatomical order," Cordoba said, suggesting the mammoth was cut up by humans for its meat or pelt.
Scientists hope to eventually assemble the fossils and put them on display.
From Discovery News
Jun 26, 2016
|Myrmeleontoid larvae from mid-Cretaceous Burmese amber.|
The insect fossils, which date to 100 million years ago, provide the oldest direct evidence of camouflage behavior utilizing debris, according to a study on the finds that is published in the journal Science Advances.
In this case, the creatures in disguise were green lacewing larvae, split-footed lacewings, owlflies and assassin bugs. All were found fossilized in Burmese, French and Lebanese ambers that the researchers analyzed.
Animals that might have lived alongside these insects in disguise could have included everything from dinosaurs to the world's earliest bees.
While the camouflage obviously did not save the insects from their amber entombment, it does show that they were pretty smart, the scientists suggest.
|Reconstruction of green lacewing larva based on the fossil finds.|
The scientists demonstrated their own cleverness by performing detective work that sheds light on what might have happened just before the insects died.
Most of the Burmese amber lacewing larvae were preserved with hair-like tiny growths produced by particular ferns known as gleicheniacean ferns. Two green lacewing larvae were preserved carrying these plant objects, suggesting that the larvae were closely associated with the ferns' habitats.
Read more at Discovery News
|(left) Human hair, (center) Peacock feather, (right) Crocodile skin.|
The coverings all develop from the same primordial structure that might have first emerged in the common reptilian ancestor of birds, mammals and reptiles, the new research -- published in the journal Science Advances -- strongly suggests.
"What we found is that they (hair, feathers, scales) all start from the same micro-anatomical structure, called a placode, made of a local thickening of the epidermis due to epidermal cells taking a columnar shape," Michel Milinkovitch, who co-authored the paper with Nicolas Di-Poï, told Discovery News.
|Placodes (spots stained in dark blue by the expression of an early developmental gene) are visible before the development of hair, scales and feathers in (from left to right) the mouse, the snake, the chicken and the crocodile.|
Milinkovitch and Di-Poï, from the University of Geneva's Department of Genetics & Evolution, were curious to learn more. They analyzed the molecular characteristics of skin during embryonic development in crocodiles, snakes and lizards. In doing so, they found the same anatomical placode and molecular signatures seen in mammals and birds.
Reptiles, birds and egg-laying mammals were already connected because all are known as amniotes, referring to their type of egg (amniotic) in which their embryos are embedded. Now it's known that the three animal groups share basic skin features as well, so it is likely that their common ancestor had placodes, too.
"I would say that the patterning of the skin with placodes is an evolutionary developmental innovation that allowed the ancestor of amniotes to develop some sort of bumps distributed across the skin and providing some additional mechanical protection," Milinkovitch said.
He said modern amphibians could even sport this ultra-ancient look.
"These animals are supposed to be 'naked,' but quite a few species exhibit bumps and scaly appendages that might have a link with the placodes of amniotes," he said. "After all, this could be an older innovation that occurred in the ancestor of all terrestrial vertebrates (animals with a backbone)."
Marcelo Sánchez-Villagra, a professor at the University of Zurich's Paleontological Institute and Museum, told Discovery News that the common ancestor of birds, mammals and reptiles "would not be a reptile by definition, but an animal that lived around 330 million years ago."
Sánchez-Villagra's colleague, Torsten Scheyer, added that the common ancestor was likely a "reptiliomorph," named as such "because they combine amphibian features with reptilian features."
|Illustration of the reptiliomorph Limnoscelis paludis.|
Although it appears that birds, mammals and reptiles inherited their placodes from this reptiliomorph common ancestor, clearly a lot of evolution has taken place since that early time.
To better determine how placodes can result in so many different looks, Milinkovitch and Di-Poï investigated bearded dragons. These lizards vary in appearance, with one type of bearded dragon having a lot of scales, another featuring reduced-size scales, and a third with no visible scales whatsoever.
Read more at Discovery News