Sep 26, 2017

Pigeons better at multitasking than humans

Sara Letzner had humans compete against pigeons in a behavioural experiment.
Pigeons are capable of switching between two tasks as quickly as humans -- and even more quickly in certain situations. These are the findings of biopsychologists who had performed the same behavioural experiments to test birds and humans. The authors hypothesize that the cause of the slight multitasking advantage in birds is their higher neuronal density.

Dr Sara Letzner and Prof Dr Dr h. c. Onur Güntürkün from Ruhr-Universität Bochum published the results in the journal "Current Biology" in collaboration with Prof Dr Christian Beste from the University Hospital Carl Gustav Carus at Technische Universität Dresden.

"For a long time, scientists used to believe the mammalian cerebral cortex to be the anatomical cause of cognitive ability; it is made up of six cortical layers," says Sara Letzner. In birds, however, such a structure does not exist. "That means the structure of the mammalian cortex cannot be decisive for complex cognitive functions such as multitasking," continues Letzner.

Six times as densely packed

The pallium of birds does not have any layers comparable to those in the human cortex; but its neurons are more densely packed than in the cerebral cortex in humans: pigeons, for example, have six times as many nerve cells as humans per cubic millimetre of brain. Consequently, the average distance between two neurons in pigeons is fifty per cent shorter than in humans. As the speed at which nerve cell signals are transmitted is the same in both birds and mammals, researchers had assumed that information is processed more quickly in avian brains than in mammalian brains.

They tested this hypothesis using a multitasking exercise that was performed by 15 humans and 12 pigeons. In the experiment, both the human and the avian participants had to stop a task in progress and switch over to an alternative task as quickly as possible. The switchover to the alternative task was performed either at the same time the first task was stopped, or it was delayed by 300 milliseconds.

What makes pigeons faster

In the first case, real multitasking takes place, which means that two processes are running simultaneously in the brain, those being the stopping of the first task and switching over to the alternative task. Pigeons and humans both slow down by the same amount under double stress.

In the second case -- switching over to the alternative task after a short delay -- the processes in the brain undergo a change: the two processes, namely stopping the first task and switching over to the second task, alternate like in a ping-pong game. For this purpose, the groups of nerve cells that control both processes have to continuously send signals back and forth. The researchers had assumed that pigeons must have an advantage over humans because of their greater nerve cell density. They were, in fact, 250 milliseconds faster than humans.

Read more at Science Daily

Minimal Consciousness Restored in Man Who Was in a Vegetative State for 15 Years

Persistent vegetative states lasting longer than 12 months has long been considered irreversible. But a 35-year-old man severely injured in a car accident was partially revived by vagus nerve stimulation after lying in a vegetative state for 15 years.

The technique has been in use for many years for treating people with epilepsy or depression. But this is the first time that doctors attempted to treat a vegetative patient with the technique.

The vagus nerve connects the human brain stem to the heart, lungs, and digestive tract. It's the longest nerve in the body's autonomous nervous system, which mostly regulates unconscious functions like heart rate, digestion, and breathing.

Angela Sirigu, who led the research at the Institute of Cognitive Sciences – Marc Jeannerod in Lyon, France, said the technique could trigger a radical change in neurological treatments worldwide.

“Brain plasticity and brain repair are still possible even when hope seems to have vanished,” Sirigu said in a statement accompanying publication of research describing the procedure.

The research team began the experiment by looking for a particularly difficult case, to reduce the possibility that any improvements weren't simply a matter of chance and good timing. The patient chosen for the experiment had shown no signs of improvement in 15 years.

Doctors then implanted a vagus nerve simulator in the man's chest designed to send small pulses of electricity up the vagus nerve and into the brain.

After a month of constant stimulation, the patient's movements and brain activity improved significantly. He responded to simple commands, such as following an object with his eyes and turning his head upon request.

Computer monitoring of the patient’s brain activity confirmed major changes took place. Imaging scans showed increased metabolic activity in areas of the brain associated with movement, awareness, and sensation. A series of electroencephalogram tests suggested that the patient had improved from a “vegetative state” to a “minimally conscious state.”

By stimulating the vagus nerve, “it is possible to improve a patient's presence in the world,” Sirigu said.

The research was published in the journal Current Biology.

An estimated 25,000 people in the US lie in a vegetative state at any given time.

While the new study marks a positive development, researchers caution that the study is, by design, extremely limited in scope.

“We need to be a little cautious about this, because it's just one patient,” said neurologist Hae Won Shin, an associate professor at the University of North Carolina School of Medicine who was not involved in the research. “I'm really glad to hear that the patient responded positively to vagus nerve stimulation treatment after 15 years in a vegetative state, but it's only one case.”

The researchers are currently planning a larger collaborative study to confirm the therapeutic potential of VNS for patients in a vegetative state. The initial study was supported by France's National Center for Scientific Research, the French National Research Agency, and by a grant from the University of Lyon

Hae, who specializes in epileptic disorders, said vagus nerve stimulation has a track record of proven efficacy in treating certain disorders — but there's a caveat: No one is quite sure how it works.

Read more at Seeker

Sep 25, 2017

Genes are controlled by 'Nano footballs,' scientists discover

Rendering of DNA.
Research at the University of York has revealed that genes are controlled by 'nano footballs' -- structures that look like footballs but 10 million times smaller than the average ball.

By placing tiny glowing probes on transcription factors -- special chemicals inside cells which control whether a gene is switched 'on' or 'off' -- researchers gained a remarkable new insight into the way in which genes are controlled.

Crucially, they discovered that transcription factors operate not as single molecules as was previously thought, but as a spherical football-like cluster of around seven to ten molecules of roughly 30 nanometres in diameter.

The discovery of these nano footballs will not only help researchers understand more about the basic ways in which genes operate, but may also provide important insights into human health problems associated with a range of different genetic disorders, including cancer.

The research, supported by the Biotechnology and Biological Sciences Research Council (BBSRC) and published in eLife was carried out by scientists from the University of York, and the University of Gothenburg and Chalmers University of Technology, Sweden.

The researchers employed advanced super-resolution microscopy to look at the nano footballs in real time, using the same type of yeast cells utilised in baking and brewing beer.

Professor Mark Leake, Chair of Biological Physics at the University of York who led the work, said: "Our ability to see inside living cells, one molecule at a time, is simply breathtaking.

"We had no idea that we would discover that transcription factors operated in this clustered way. The textbooks all suggested that single molecules were used to switch genes on and off, not these crazy nano footballs that we observed."

The team believe the clustering process is due to an ingenious strategy of the cell to allow transcription factors to reach their target genes as quickly as possible.

Professor Leake said: "We found out that the size of these nano footballs is a remarkably close match to the gaps between DNA when it is scrunched up inside a cell. As the DNA inside a nucleus is really squeezed in, you get little gaps between separate strands of DNA which are like the mesh in a fishing net. The size of this mesh is really close to the size of the nano footballs we see.

"This means that nano footballs can roll along segments of DNA but then hop to another nearby segment. This allows the nano football to find the specific gene it controls much more quickly than if no nano hopping was possible. In other words, cells can respond as quickly as possible to signals from the outside, which is an enormous advantage in the fight for survival."

Genes are made from DNA, the so-called molecule of life. Since the discovery that DNA has a double helix shape, made in the 1950s by pioneering biophysics researchers, much has been learned about transcription factors which can control whether a gene is switched on or off.

If a gene is switched on, specialised molecular machinery in the cell reads off its genetic code and converts it into a single protein molecule.Thousands of different types of protein molecules can then be made, and when they interact that can drive the building of all of the remarkable structures found inside living cells.

The process of controlling which genes are switched on or off at any particular point in time is fundamental to all life. When it goes wrong, this can lead to serious health problems. In particular, dysfunctional switching of genes can result in cells which grow and divide uncontrollably, which can ultimately lead to cancer.

Read more at Science Daily

Ancient Egyptians Provided a Proper Burial to a Statue of a Revered Deity

Osiris statuette
After years of being washed, perfumed and fed in ancient Egypt, the statue of a revered Egyptian deity was given a proper burial with other "dead" statues more than 2,000 years ago, a new study finds.

Ancient Egyptians buried the statue of the deity Ptah — the god of craftsmen and sculptors — with other revered statues, including those of a sphinx, baboon, cat, Osiris, and Mut, in a pit next to Ptah's temple.

The statue of Ptah had likely sat in the temple for years, but it and the other sacred objects were respectfully buried after they accumulated damage and were declared useless by the ancient Egyptians, the researchers said.

"We can consider that when a new statue was erected in the temple, this one [of Ptah] was set aside in a pit," said study co-researcher Christophe Thiers, director of the French-Egyptian Center for the Study of the Temples of Karnak. "The other artifacts were also previously damaged during their ‘lifetime’ in the temple, and then they were buried with the Ptah statue."

Archaeologists discovered the pit in December 2014 at Karnak, an Egyptian temple precinct, and spent about a month excavating its rich assemblage. The pit held 38 objects, including:

Fourteen statuettes and figurines of Osiris.
Eleven fragments of inlay from statues.
The inlay included that of an iris, a cornea, a false beard, a cap, a strand of hair and an inlay plaque.
Three baboon statuettes (representing the god Thoth).
Two statuettes of the goddess Mut (one with hieroglyphic inscriptions).
Two unidentified statuette bases.
One head and one fragmentary statuette of a cat (Bastet).
One small fragmentary faience stele (a stone slab) recording the name of the god Ptah.
One head of a statuette of a man in gilded limestone.
One lower part of a statue of the seated god Ptah, sawn and repaired.
One sphinx.
One unidentified metal piece.

The favissa contained 38 objects, including (clockwise from top left) a male head made of gilded limestone, the lower part of the limestone statue of the god Ptah, a statuette of Osiris, and a limestone sphinx.
It appeared that the artifacts were buried in a certain order. After digging the pit, also known as a favissa (a cache of sacred objects that are no longer in use), the ancient Egyptians would have put down the lower part of Ptah's limestone statue. The statue was large, and it probably took two to three people to carry it, the researchers said.

Next to the statue, the Egyptians would have placed a wooden effigy of the god Osiris that had metal appliqué, including a beard and two feathers in its crown. Then, the other artifacts would have been distributed around these two artifacts, which were then covered with about 8 inches (20 centimeters) of backfill. This is where the ancient Egyptians placed a statue of a small limestone sphinx.

The pit was then covered with more backfill. At the top, the Egyptians placed a small male head made of gilded limestone, likely for protection, the researchers said.

The objects were made at different times, the researchers found. The statue of Ptah dates to the New Kingdom; the style of the sphinx supports a late Ptolemaic date; and the gilded head dates to the early Ptolemaic period, the researchers said. However, by studying the site's rock layers, the researchers found that the artifacts were buried by the temple's priests during the second half of the Ptolemaic period, between the second century B. and the middle of the first century BC, the researchers wrote in the study.

Read more at Seeker

This Airship Might Provide a Better View of the Big Bang’s Relic Radiation

Airlander 10’s first flight on 2016 August 17
Despite the universe being billions of years old, today we can still see the early stages of the its expansion through a phenomenon called cosmic microwave background radiation. NASA describes the CMB as "literally the remnant heat left over from the Big Bang."

The energy is visible in microwave wavelengths, which means it can't be seen unless you're above the atmosphere somewhere. But observations taken for spacecraft caught something extraordinary: a remarkably uniform background about 2.275 degrees Celsius (36 degrees Fahrenheit) above absolute zero, or the coldest possible temperature allowed by physics. Mapping and understanding the tiny variations of temperature at the part per million level that require ongoing observations and modeling.

Scientists have observed the CMB before with spacecraft, and even a specially adapted 747 called SOFIA (Stratospheric Observatory for Infrared Astronomy). A proposal published in the Monthly Notices of the Royal Astronomical Society suggests using an airship called Airlander 10, which is cheaper than a spacecraft, but allows for lengthy observations of up to weeks at a time.

"The main advantage is flight duration," Stephen Feeney, lead author and a postdoctoral researcher at the Flatiron Institute's Center for Computational Astrophysics in New York City, told Seeker in an email.

"Using remote piloting, Airlander 10 should fly for up to three weeks at a time,” he said. “We could therefore observe the sky roughly 20 times longer on an Airlander 10 flight than using, for example, a 747 like SOFIA. Airlander 10 is also able to operate without an airport, and should have a significantly smaller environmental impact, as it generates 60 percent of its lift through buoyancy."

An image of the cosmic microwave background radiation, including the foreground signal from the Milky Way galaxy (in red). This picture is based on observations from NASA's Wilkinson Microwave Anisotropy Probe, which operated from 2001 to 2010.
Airlander 10 is a hybrid airship — meaning that part of its lift, or ability to fly, comes from being filled with lighter-than-air gas, and the other part of its lift comes from aerodynamics. Originally designed and built for the US Army, the military sold the airship back to the manufacturer in 2016 for civilian use. It is now in test flights, having survived an accident, which damaged the airship, but left the crew unharmed. This means that Feeney's proposal is still in a very early stage.

"We are currently working with Hybrid Air Vehicles, Airlander 10's designers, to ascertain whether the vibrations from Airlander 10's engines are low enough to allow a CMB telescope to gather useful data,” Feeney said. “If this critical criterion is satisfied, we will look to develop the concept further.”

Feeney's research, in part, concerns how to operate CMB detectors at higher altitudes, which requires knowledge of how they perform at sea level, then extrapolating their performance at higher and higher altitudes. The research also seeks to ways to avoid confusing radiation from galaxies, which are closer to us than the CMB. Both galaxies and CMB can emit radiation at the same wavelengths.

"These foregrounds can be cleaned from the CMB by observing the sky at many different wavelengths, as the amplitudes of the foregrounds and CMB change differently with wavelength," Feeney said.

Read more at Seeker

Cosmic Rays Originate Far Beyond the Milky Way

Something out in space has been bombarding Earth with incredibly high energy particles called cosmic rays. The origin of cosmic rays has been a mystery since their discovery over a century ago.

But twelve years of data from an unusual observatory in South America has now confirmed that cosmic rays with the highest energies come from sources outside the Milky Way. In particular, the majority of the high-energy particles originate from an area of the sky that lies almost opposite from the center of our own galaxy, in a region of space with a high concentration of other galaxies. 

“The distribution of arrival directions of the highest energy cosmic ray particles has an enhancement in a broad patch of the sky which is roughly 120 degrees away from a line pointing from Earth to the center of our Milky Way galaxy, meaning cosmic rays coming to the Earth from that patch must be coming from other galaxies,” Gregory Snow, a physics professor from the University of Nebraska-Lincoln, said in an email to Seeker. He is also the education and outreach coordinator for the Pierre Auger Observatory, which is located in western Argentina and was the source of the data.

Snow and a group of more than 400 scientists from 18 countries published last week their analysis of cosmic rays in the journal Science.

He explained the direction of the enhanced patch is consistent with a region of galaxies that is more dense than other regions of the sky.

“This makes sense since we might expect more cosmic ray particles coming from places in the universe where there is a lot of ‘stuff,’” he said.

Scientists collected a dozen years of data on cosmic rays at the Pierre Auger Observatory in Argentina.
Cosmic rays are electrically charged particles, such as protons, that travel near the speed of light. They strike Earth from all directions, and have energies up to one hundred million times higher than those created in man-made accelerators like the Large Hadron Collider. These high-energy cosmic rays — ones with energies reaching quintillions of electron volts — are different from the ones emitted by our sun during flares and coronal mass ejections.

"The sun emits low-energy cosmic ray particles that are detected here on Earth, but they are nowhere near as high energy as the particles detected at the Auger Observatory," Snow explained in a press release.

When the high energy cosmic rays travel across space, the particles can be deflected by magnetic fields, which scramble their paths and sometimes mask their origins.

Detecting cosmic rays is even more challenging because the highest energy particles — the ones that are most mysterious and rare — reach Earth at a rate of only one particle per square kilometer each year.

That’s where the Pierre Auger Observatory comes in. The observatory uses 1,660 tanks filled with ultra-pure water, spread over a 1,800-square-mile (3,000-square-kilometer) grid in Argentina. Each 3,000-gallon (12,000 liter) tank is separated from the other tanks by about a mile (1.5 km) and are enclosed to make them completely dark inside. When cosmic ray particles pass through the water, their electromagnetic shock waves produce radiation called Cherenkov light that can be measured by special instruments mounted in the tanks.

There are also separate, independent detectors called air fluorescence telescopes that track the development of what is called “air showers.” Cosmic rays interacting with Earth’s atmosphere produce a cascade effect, creating extensive showers that contain billions of secondary particles. The air fluorescence telescopes observe ultraviolet light emitted high in Earth's atmosphere from the showers.  These air showers can also cause nearly simultaneous bursts of light in more than five tanks.

Using the two detectors, scientists can determine the energy of the primary cosmic ray particles based on the amount of light they detect from a sample of secondary particles. Additionally, slight differences in the detection times at different tank positions help scientists determine the trajectory of the incoming cosmic rays.

In over a dozen years of operation, the Auger Observatory has collected some of the highest quality information about the types of particles in primary cosmic rays. Comparing results from the different types of detectors also helps scientists reconcile the two sets of data and produce the most accurate results about the energy of primary cosmic rays.

University of Nebraska-Lincoln physics professor Gregory Snow stands near one of the cosmic ray particle detectors used by the Pierre Auger Observatory in Argentina.
But why study these high-energy cosmic rays?

For one thing, scientists like a good mystery and the origins of cosmic rays is one of the biggest unknowns in physics.

But understanding them better could lead to improved insights on fundamental physics, such as how our universe was created, and why objects have mass. Snow told Seeker high-energy cosmic rays are clues to the very structure of the universe.

“High-energy cosmic ray particles are one of several messengers from outer space that we use to learn about the structure of the universe, for example, the distribution of where the billions of other galaxies apart from the Milky Way are located,” he said. “We now know that galaxies are not uniformly distributed in outer space. Rather they group themselves in clusters and super-clusters.”

Also, scientists don’t know the exact source of high-energy cosmic rays. There have been theories, but the intense conditions needed to generate such energetic particles can be mind-boggling.

“We know that shock waves coming from stars dying in the form of a supernova could accelerate cosmic ray particles up to energies reaching about 10 to the 15th electron volts,” Snow explained. “But our paper is about cosmic ray particles of much higher energies, greater than 8 times 10 to the 18th electron volts. We can only speculate what the sources of these particles may be.”

Snow said physicists can learn the most about specific sources by studying the arrival directions of the very highest energy particles, since their measured arrival directions essentially point straight back to their sources.

Read more at Seeker

Sep 24, 2017

World's first 'molecular robot' capable of building molecules

Molecular robotics represents the ultimate in the miniaturization of machinery, researchers say.
Scientists at The University of Manchester have created the world's first 'molecular robot' that is capable of performing basic tasks including building other molecules.

The tiny robots, which are a millionth of a millimetre in size, can be programmed to move and build molecular cargo, using a tiny robotic arm.

Each individual robot is capable of manipulating a single molecule and is made up of just 150 carbon, hydrogen, oxygen and nitrogen atoms. To put that size into context, a billion billion of these robots piled on top of each other would still only be the same size as a single grain of salt.

The robots operate by carrying out chemical reactions in special solutions which can then be controlled and programmed by scientists to perform the basic tasks.

In the future such robots could be used for medical purposes, advanced manufacturing processes and even building molecular factories and assembly lines. The research will be published in Nature on Thursday 21st September.

Professor David Leigh, who led the research at University's School of Chemistry, explains: 'All matter is made up of atoms and these are the basic building blocks that form molecules. Our robot is literally a molecular robot constructed of atoms just like you can build a very simple robot out of Lego bricks. The robot then responds to a series of simple commands that are programmed with chemical inputs by a scientist.

'It is similar to the way robots are used on a car assembly line. Those robots pick up a panel and position it so that it can be riveted in the correct way to build the bodywork of a car. So, just like the robot in the factory, our molecular version can be programmed to position and rivet components in different ways to build different products, just on a much smaller scale at a molecular level.'

The benefit of having machinery that is so small is it massively reduces demand for materials, can accelerate and improve drug discovery, dramatically reduce power requirements and rapidly increase the miniaturisation of other products. Therefore, the potential applications for molecular robots are extremely varied and exciting.

Prof Leigh says: 'Molecular robotics represents the ultimate in the miniaturisation of machinery. Our aim is to design and make the smallest machines possible. This is just the start but we anticipate that within 10 to 20 years molecular robots will begin to be used to build molecules and materials on assembly lines in molecular factories.'

Whilst building and operating such tiny machine is extremely complex, the techniques used by the team are based on simple chemical processes.

Prof Leigh added: 'The robots are assembled and operated using chemistry. This is the science of how atoms and molecules react with each other and how larger molecules are constructed from smaller ones.

Read more at Science Daily

Scientists sequence asexual tiny worm whose lineage stretches back 18 million years

Pictured is Diploscapter pachys (D. pachys), a newly sequenced roundworm that is approximately one-third of a millimeter long and one of a very few known animals that have only a single chromosome.
A team of scientists has sequenced, for the first time, a tiny worm that belongs to a group of exclusively asexual species that originated approximately 18 million years ago -- making it one of the oldest living lineages of asexual animals known. The work reveals how it has escaped the evolutionary dead end usually met by organisms that do not engage in sex.

"Scientists have been trying to understand how some animals can survive for millions of years without sex because such strict, long-term abstinence is very rare in the animal world," explains New York University Biology Professor David Fitch, one of the co-authors of the research. "This phenomenon is a significant one in understanding evolutionary genetics because it runs counter to the widely accepted view that sexual reproduction is required to eliminate deleterious mutations and for adaptation to a changing environment."

"For example, in the short term, inheriting copies of both parents' genes usually provides good insurance against mutations that might kill the function of one of those gene copies -- a process called complementation," Fitch continues. "In the long term, producing offspring via intercourse allows for adaptation to changing conditions over time because it produces variation through genetic shuffling, or recombination. However, because such shuffling does not occur within asexual species, they tend to go extinct rapidly. So, it has been a longstanding mystery in biology how some asexual animals have survived for so many generations."

The research, conducted by researchers in NYU's Center for Genomics and Systems Biology and Duke University's Center for Genomic and Computational Biology, appears in the journal Current Biology.

The newly sequenced worm, Diploscapter pachys, is a tiny, transparent, free-living roundworm and closely related to Caenorhabditis elegans, an organism commonly used for biomedical research.

Unlike C. elegans, however, D. pachys is asexual.

In making this determination, the scientists used DNA to derive a genealogy that revealed D. pachys belongs to a group of exclusively asexual species that originated approximately 18 million years ago.

In a closer examination of how D. pachys reproduces, the research team found that, like many other asexual organisms, the process of making germ cells -- sperm or ova -- had been modified to prevent recombination, or the reshuffling that results from sexual reproduction.

"Basically, the animals were cloning themselves," explains Fitch. In addition, when the researchers studied its chromosomes, they found something even more surprising: there was only one pair of chromosomes.

Close relatives, such as C. elegans, have 5-7 chromosomes, but a single-chromosome pair, the scientists say, is so rare in higher organisms that only two other animal species are known with this condition: an ant and a parasitic roundworm.

The researchers decided to sequence the genome of D. pachys to test how the single chromosome was structured, whether by loss or by fusion of multiple ancestral chromosomes.

Their results showed that D. pachys fuses the six chromosomes of its ancestor into a single chromosome and skips the first division of meiosis, where genes are recombined, so that its offspring keeps the high genetic diversity of the parents.

Read more at Science Daily

Sep 22, 2017

Why poison frogs don't poison themselves

The phantasmal poison frog, Epipedobates anthonyi, is the original source of epibatidine, discovered by John Daly in 1974. In fact, epibatidine is named for frogs of this genus. Epibatidine has not been found in any animal outside of Ecuador, and its ultimate source, proposed to be an arthropod, remains unknown. This frog was captured at a banana plantation in the Azuay province in southern Ecuador in August 2017.
Don't let their appearance fool you: Thimble-sized, dappled in cheerful colors and squishy, poison frogs in fact harbor some of the most potent neurotoxins we know. With a new paper published in the journal Science, scientists are a step closer to resolving a related head-scratcher -- how do these frogs keep from poisoning themselves? And the answer has potential consequences for the fight against pain and addiction.

The new research, led by scientists at The University of Texas at Austin, answers this question for a subgroup of poison frogs that use the toxin epibatidine. To keep predators from eating them, the frogs use the toxin, which binds to receptors in an animal's nervous system and can cause hypertension, seizures, and even death. The researchers discovered that a small genetic mutation in the frogs -- a change in just three of the 2,500 amino acids that make up the receptor -- prevents the toxin from acting on the frogs' own receptors, making them resistant to its lethal effects. Not only that, but precisely the same change appeared independently three times in the evolution of these frogs.

"Being toxic can be good for your survival -- it gives you an edge over predators," said Rebecca Tarvin, a postdoctoral researcher at UT Austin and a co-first author on the paper. "So why aren't more animals toxic? Our work is showing that a big constraint is whether organisms can evolve resistance to their own toxins. We found evolution has hit upon this same exact change in three different groups of frogs, and that, to me, is quite beautiful."

There are hundreds of species of poisonous frogs, each of which uses dozens of different neurotoxins. Tarvin is part of a team of researchers, including professors David Cannatella and Harold Zakon in the Department of Integrative Biology, who have been studying how these frogs evolved toxic resistance.

For decades, medical researchers have known that this toxin, epibatidine, also can act as a powerful nonaddictive painkiller. They've developed hundreds of compounds from the frogs' toxin, including one that advanced in the drug-development process to human trials before being ruled out due to other side effects.

The new research -- showing how certain poison frogs evolved to block the toxin while retaining use of receptors the brain needs -- gives scientists information about epibatidine that could eventually prove helpful in designing drugs such as new pain relievers or drugs to fight nicotine addiction.

"Every bit of information we can gather on how these receptors are interacting with the drugs gets us a step closer to designing better drugs," said Cecilia Borghese, another co-first author of the paper and a research associate in the university's Waggoner Center for Alcohol and Addiction Research.

Changing the Lock

A receptor is a type of protein on the outside of cells that transmits signals between the outside and the inside. Receptors are like locks that stay shut until they encounter the correct key. When a molecule with just the right shape comes along, the receptor gets activated and sends a signal.

The receptor that Tarvin and her colleagues studied sends signals in processes like learning and memory, but usually only when a compound that is the healthy "key" comes into contact with it. Unfortunately for the frogs' predators, toxic epibatidine also works, like a powerful skeleton key, on the receptor, hijacking cells and triggering a dangerous burst of activity.

The researchers found that poison frogs that use epibatidine have developed a small genetic mutation that prevents the toxin from binding to their receptors. In a sense, they've blocked the skeleton key. They also have managed, through evolution, to retain a way for the real key to continue to work, thanks to a second genetic mutation. In the frogs, the lock became more selective.

Fighting Disease

The way that the lock changed suggests possible new ways to develop drugs to fight human disease.

The researchers found that the changes that give the frogs resistance to the toxin without changing healthy functioning occur in parts of the receptor that are close to, but don't even touch epibatidine. Borghese and Wiebke Sachs, a visiting student, studied the function of human and frog receptors in the lab of Adron Harris, another author on the paper and associate director of the Waggoner Center.

"The most exciting thing is how these amino acids that are not even in direct contact with the drug can modify the function of the receptor in such a precise way," Borghese said. The healthy compound, she continued, "keeps working as usual, no problem at all, and now the receptor is resistant to epibatidine. That for me was fascinating."

Understanding how those very small changes affect the behavior of the receptor might be exploited by scientists trying to design drugs that act on it. Because the same receptor in humans is also involved in pain and nicotine addiction, this study might suggest ways to develop new medications to block pain or help smokers break the habit.

Retracing Evolution

Working with partners in Ecuador, the researchers collected tissue samples from 28 species of frogs -- including those that use epibatidine, those that use other toxins and those that are not toxic. Tarvin and hear colleagues Juan C. Santos from St. John's University and Lauren O'Connell from Stanford University sequenced the gene that encodes the particular receptor in each species. She then compared subtle differences to build an evolutionary tree representing how the gene evolved.

This represents the second time that Cannatella, Zakon, Tarvin and Santos have played a role in discovering mechanisms that prevent frogs from poisoning themselves. In January 2016, the team identified a set of genetic mutations that they suggested might protect another subgroup of poison frogs from a different neurotoxin, batrachotoxin. Research published this month was built on their finding and conducted by researchers from the State University of New York at Albany, confirming that one of UT Austin's proposed mutations protects that set of poison frogs from the toxin.

Read more at Science Daily

Solving the Easter Island population puzzle

A detailed study of Easter Island's farming potential reveals the population may have reached 17,500 people in its heyday, which could help unravel the mystery of its giant statues.
Easter Island, known as Rapa Nui by its inhabitants, has been surrounded in mystery ever since the Europeans first landed in 1722. Early visitors estimated a population of just 1,500-3,000, which seemed at odds with the nearly nine hundred giant statues dotted around the Island. How did this small community construct, transport and erect these large rock figures?

A new study, published in the open-access journal Frontiers in Ecology and Evolution, hopes to unravel this mystery by giving the best estimate yet of the maximum population size sustained by Easter Island in its heyday.

"Despite its almost complete isolation, the inhabitants of Easter Island created a complicated social structure and these amazing works of art before a dramatic change occurred," says Dr. Cedric Puleston, lead author of this study, based at the Department of Anthropology, University of California, Davis, USA. "We've tried to solve one piece of the puzzle -- to figure out the maximum population size before it fell. It appears the island could have supported 17,500 people at its peak, which represents the upper end of the range of previous estimates."

He adds, "If the population fell from 17,500 to the small number that missionaries counted many years after European contact, it presents a very different picture from the maximum population of 3,000 or less that some have suggested."

Previous archaeological evidence implies the indigenous people numbered far greater than the 1,500-3,000 individuals encountered in the 18th century. The population history of the island remains highly controversial. In addition to internal conflict, the population crash has been attributed to "ecocide," in which the Island's resources were exhausted by its inhabitants, reducing its ability to support human life.

Puleston and his colleagues examined the agricultural potential of the Island before these events occurred, to calculate how many people the Island could sustain.

"The project, funded by the U.S. National Science Foundation, involved a number of really good researchers, including archaeologists, a local expert in Rapa Nui culture, a soil scientist, a biogeochemist, and a population biologist, to get a thorough picture of what the island was like before European contact," he explains.

"We examined detailed maps, took soil samples around the Island, placed weather stations, used population models and estimated sweet potato production. When we had doubts about one of these factors we looked at the range of its potential values to work out different scenarios."

They found 19% of the Island could have been used to grow sweet potatoes, which was the main food crop. By using information on how birth and death rates at various ages depend on food availability, the researchers calculated the population size that level of production could sustain.

"The result is a wide range of possible maximum population sizes, but to get the smallest values you have to assume the worst of everything," says Puleston. "If we compare our agriculture estimates with other Polynesian Islands, a population of 17,500 people on this size of island is entirely reasonable."

Read more at Science Daily

Children Internalize Gender Stereotypes as Early as Age Ten

Girls are vulnerable and boys are stronger. Boys should have the courage to ask a girl out. If a boy gets his nails done, there’s definitely something feminine about him. Girls should prepare to become wives and mothers, and boys should focus on their careers.

In countries across the world, regardless of economic status, gender stereotypes are thriving. For sure, cultural variations exist, but a new global study of adolescents published in the US-based Journal of Adolescent Health suggests stereotypes begin seeping into the mindset of children early — as early as age 10.

Internalizing unequal gender norms has both immediate and long-term consequences on sexual, reproductive, and mental health, including risk of HIV and other sexually transmitted diseases, complications associated with early pregnancy, substance and alcohol abuse, depression, and suicide. These health concerns, according to the study, begin during adolescence and can carry over into adulthood.

“We found children at a very early age — from the most conservative to the most liberal societies — quickly internalize this myth that girls are vulnerable and boys are strong and independent,” Robert Blum of Johns Hopkins University and director of the Global Early Adolescent Study said in a press release accompanying publication of the study.

The research was a collaboration between the Johns Hopkins Bloomberg School of Public Health and the World Health Organization.

Researchers across 15 countries, including the United States, China, Kenya, Belgium, Nigeria, India, South Africa, and Scotland, among others, interviewed over 400 children aged 10 to 14, along with their parents.

Perception of distinct, gendered roles takes root in a child’s mindset between the age of 10 and 14, according to the report. And while the impact of these stereotypes is not surprising, “the fact that they are so common across cultures and economic status and ingrained in children at such a relatively young age, is unexpected,” Kristin Mmari, a professor at Johns Hopkins University and lead researcher on study, told Seeker.

A 12-year-old girl participating in the study from Delhi recalled one of her female classmates being scolded by a teacher for wearing short skirts and playing with boys. “After the school got over, she was sitting alone when a boy went inside the school and raped her as she wearing short skirt,” the girl is quoted as saying in the study.

The report also highlights progress in challenging gender norms.

In Belgium, girls’ participation in sports was celebrated. “Girls are [one] hundred percent [as involved as] boys in football,” a 13-year-old boy is quoted saying. “[Today] there are more girls playing football than boys.”

In China, however, an 11-year-old boy said girls must display certain male traits like strength, fearlessness, and indifference to pain, before successfully participating in the sport.

A message of strength and virility being passed onto boys across cultures is equally threatening to their development, the study suggests. In China, India, Belgium, and the United States, researchers saw that girls are pushing the boundaries of gender norms more than boys. But boys exploring stereotypically female behavior were seen as socially inferior. As a result, they suffer and tend to be more self-harming, said the researchers.

Mmari says stereotypes can be deconstructed and reformed and are amenable to change. “But do I think it will happen quickly? No,” she said.

Read more at Seeker

Porpoise Burial by Medieval Monks Creates Puzzling Grave Mystery

A porpoise from the medieval period was found buried in what appears to be a formal grave on the island of Chapelle dom Hue in the English Channel.
Folklore holds that the little island of Chapelle Dom Hue, in the English Channel west of Guernsey, was the location of a scenic retreat for medieval monks from the Benedictine priory of Lihou, which is a slightly larger island just to the south. Guernsey archaeologist Philip de Jersey and his colleagues are currently excavating the site to determine, in part, what the monks might have left there.

Recently, de Jersey and his team spotted the outline of a feature in the soil that looked like a grave.

“It certainly resembled medieval graves we have excavated in several sites on the island, and it was only a little way off the east-west orientation, as one would usually expect,” de Jersey told Seeker from the site.

A few days later, he and his team started to excavate the feature and uncovered a skull, which he initially thought was the top of a human skull. While dirt was removed, however, the skull grew ever larger in appearance.

As it turns out, the skull and other remains belonged, not to a human, but to a porpoise. The discovery is the world’s only known porpoise burial from the medieval era or earlier.

The archaeologists were astonished.

“It was entirely consistent with a human burial, which is one of the most puzzling aspects,” de Jersey said. “The grave cut has been dug very carefully, with vertical sides and a flat base cut into the underlying bedrock. This has taken some considerable care and effort.”

The buried porpoise as it was first being uncovered.
Like the beginning of a great murder mystery — the porpoise does appear to have been killed — there is a collection of clues and other information, some of which may have nothing to do with the burial.

So far, de Jersey and his team on the island have uncovered the ruins of a building there erected on an east-west alignment, which supports a religious function, according to the researchers.

“It was quite a substantial structure, small in size, but with thick walls,” de Jersey said.

He added that they have also found a lot of old pottery known as Normandy gritty ware, which was imported to the Channel Islands between the late 10th and early-15th centuries. A priory on Lihou was in use from the mid 12th to the early 14th or early-15th century, but the Chapelle Dom Hue pottery suggests that this smaller island was only occupied by the monks for a relatively short time, probably in the later-14th century.

A photo taken from west of the site, with the medieval building at Chapelle Dom Hue visible in the foreground
Evidence for an even earlier occupation of Chapelle Dom Hue was also found, with flint tools going back to the Neolithic Period (15,200 BC–2,000 BC). The porpoise burial, though, is at the medieval level of the site.

The researchers suspect that the animal was butchered before it was put into the ground.

“The bone preservation, apart from the skull, is very poor in our acidic soul, but it appears as though there are various articulated portions in the grave, not in the association one would expect if it was a complete body,” de Jersey explained.

The monks may therefore have viewed the porpoise more as food than as a revered, sentient being.

“One possibility we have considered is that the ‘grave’ is not a grave at all, but a pit carefully cut in which the butchered porpoise was buried in salt, in order to preserve portions of it,” de Jersey said. “There is contemporary literary evidence of porpoises, or parts of porpoise, being around for longer than it would have been fresh, therefore it must have been preserved somehow, whether through drying or salting.”

Researchers excavating at Chapelle Dom Hue, with Guernsey in the distance
Salting of fish and other edible marine life at the time was normally done in barrels, though. The researchers wonder if the large size of the porpoise might have necessitated a different approach for preparing it.

“If that’s true, then obviously it was never recovered, for some reason — or perhaps it just didn’t work as a technique, so they left it in the ground,” de Jersey said.

Medieval cookbooks do include dishes with porpoise as an ingredient. The late-14th century chef’s tome Forme of Cury, for example, contains such a recipe.

Read more at Seeker

Nanoparticles Keep 3D-Printed Alloys From Cracking

The nanoparticle-functionalized powder is fed into a 3D printer, which layers the powder and laser-fuses each layer to construct a 3D object.
Metals have not yet reached their 3D-printing potential. Of the more than 5,500 alloys used in manufacturing today, many cannot undergo the laser-based melting and quick cooling times without cracking or other defects.

Now researchers at HRL Laboratories, in Malibu, California have figured out that adding nanoparticles to the mix could prevent 3D-printed metals from cracking. Bringing metals into the additive manufacturing arena could lead to innovations in industries from aerospace to biomedicine by improving on conventional casting methods. Using 3D printing also allows products to be customized in a short period of time, making them available for sale more quickly.

“What we’re hoping to do is remove one of the constraints,” John Martin, a researcher at HRL Labs, told Seeker. “If you don’t have to worry about whether the material is going to be strong enough once you produce a part, you can focus on the next step, which is opening up the ideas of young engineers, who are thinking about brand new [design] geometries.”

In lab experiments the researchers 3D-printed two different kinds of aluminum alloys that not only didn’t crack, but were as strong as steel and one-third the weight. Martin and his colleagues published their research findings in the journal Nature.

Martin, who has studied metallurgy, knew the problem was at the atomic level. Metals are crystals and their atoms line up in repeating patterns that make up grains. There are sometimes defects at the boundaries where grains meet up and those defects can cause cracks.

There was also the issue of powdered metal. The process of 3D-printing metal requires that the metal begins as a powder, which is laid down in very thin layers, each one heated with a laser in order to melt it. The molten metal must cool quickly before the next layer of powder is added and laser-heated. The intense heating and quick cooling causes metal grains to solidify in odd shapes, which can lead to cracks.

Because the grains of powder are tiny and measured in microns, Martin and his team thought they could introduce nanosized particles to beef up the metal’s strength. They used a computer program to sort through and analyze more than 4,500 different alloy and nanoparticle combinations to see which ones had atomic structures that would fit together best. The idea was that the grains of metal would glom onto the tiny nanoparticles, sort of like a water vapor droplet that nucleates around a particle of dust to create a drop of rain.

They found that a nanoparticle made of hydrogen-stabilized zirconium would work best with two different kinds of aluminum alloys. During the very first lab experiment, they laid down a thin powdery layer of metal microparticles coated with a very fine layer of nanoparticles before running the laser over it. Layer after layer, the printer created the object until it was finished.

When it was completed, the scientists cut the object in half, then polished it. There were no cracks.

“I was surprised that it worked the first time,” said Martin. “We followed physics, so I wasn’t too shocked that it worked, but it’s easy to write something down on a piece of paper. It’s much harder to follow through.”

Read more at Seeker

Sep 21, 2017

Neanderthal Boy Found in Spanish Cave Was Human-Like, but With a Larger Brain

Paleoanthropologist Antonio Rosas sits beside the skeleton of a Neanderthal child.
El Sidrón Cave in northwestern Spain preserved the remains of at least 12 Neanderthals for about 49,000 years until their discovery in 2010. Genetic evidence suggests the group — 3 adult males, 3 adult females, 3 adolescent boys, 2 juveniles, and an infant — were all related. What they were doing in the cave before their demise has intrigued archaeologists and historians since the incredible discovery.

New research on the related individuals, however, began with different, yet no less important, questions: How was Neanderthal physiological development different from that of modern humans, and how and why did Neanderthals evolve such big brains?

It has long been reported that the average Neanderthal adult brain had a volume of approximately 1520 cubic centimeters (92 cubic inches), while the average size of a modern human brain is about 1450 cubic centimeters (88 cubic inches).

Bigger brains are not necessarily always better, though, in terms of intellect. Honeybees, for example, are among the most intelligent insects, yet they obviously have very tiny brains.

Nevertheless, “Neanderthals certainly had, in their own way, a sophisticated intellect in evolutionary terms,” Antonio Rosas, a paleoanthropologist at the National Museum of Natural Sciences in Madrid, told Seeker.

Skeleton of a Neanderthal boy recovered from El Sidrón Cave in Asturias, Spain
Rosas and his colleagues conducted the new physical analysis, focusing on just one of the unearthed Neanderthals, a well-preserved boy dubbed El Sidrón J1, whose mix of baby and adult teeth suggests that he died at 7.69 years of age. The findings of the study, published in the journal Science, consist primarily of three determinations.

First, as co-author Luis Ríos of the museum and the Aranzadi Society of Sciences said during a teleconference with media, “there was no noticeable difference in the growth and maturation of this Neanderthal juvenile in comparison with modern human juveniles.”

The observed similarities could help to explain how Neanderthals and anatomically modern humans interbred: Even today, people of European and Asian descent retain Neanderthal DNA. Intriguingly, arctic indigenous peoples and East Asians today possess the biggest brains in the world. They also retain a higher percentage of early hominid — Neanderthal and Denisovan — DNA than most of us.

Their big brains may be a legacy of that heritage. Climate and latitude could be other factors affecting brain growth, along with nutrition.

The second major finding of the study is that the Neanderthal boy’s brain was still likely growing when his life was cut short. While the researchers do not yet know how he and the other Neanderthals died, they can compare other braincases with that of the remains of this young fellow.

The comparison showed that his brain was roughly 87.5 percent of the size of an average adult Neanderthal brain. A modern human of the same age, on average, tends to have 95 percent of the adult brain weight.

“This longer period of growth may have allowed larger brains and larger bodies to grow,” Rosas said. Although Neanderthals had broader bodies than modern humans, he added, their brain to overall body size ratio was still larger than that of our species. It could then be said that they had more brainpower.

Many researchers over the years have wondered why these brainy individuals then went extinct, but because Neanderthal DNA remains in current populations, these hominids were probably just absorbed into what is now known as Homo sapiens.

Researchers working inside El Sidrón Cave in Asturias, Spain
Since Neanderthal childhood development happened rather slowly, this suggests that youths spent a lot of time with parents, older relatives, and other guardians.

“That allowed them to have more time for learning, as compared to other earlier Homo species,” Rosas said. “However, it is difficult to evaluate the biological meaning of the extra learning time as compared to modern humans.”

The third and final finding of the study is that some vertebrae in the boy had not fused when he died. This is another contrast with modern humans, whose same vertebrae tend to fuse around the ages of 4 to 6 years old. The researchers do not think that the difference was due to some pathology in the boy, but rather was probably a development trait of all Neanderthals.

There was “no evidence of disease in the skeleton” of the boy, Rosas said.

Prior research determined that adult male Neanderthals stood about 5 feet 5 inches, which is only 2 inches shorter than the average height for men in many parts of Asia today. As of 10,000 years ago, European males measured about 5 feet 4 inches, reflecting a likely shrinkage before human height globally began to rise again in most regions in more recent years.

Debate continues over what species was the last common ancestor of Neanderthals and modern humans. Rosas said that some people think the last common ancestor “was Homo heidelbergensis; others think it was an earlier species, such as Homo antecessor.” Determining the answer could pinpoint when bigger brains emerged in the human lineage.

Read more at Seeker

Here’s Why the Ears of Barn Owls Are Ageless, Unlike Other Mammals

Florida, Everglades Agricultural Area, Barn Owl in flight
Even if a person has lived a rather dull, quiet life — no concerts, raucous parties, and other noisy activities — the individual’s sense of hearing will deteriorate to a certain extent over time. By age 65, most people will have lost more than 30 decibels in sensitivity at high frequencies due to age-related hearing deterioration known as presbycusis. The amount can be significantly more, depending on lifestyle and genetics, among other factors.

Barn owls, conversely, appear to experience no such age-related hearing loss. Their ears, according to new research published in the journal Proceedings of the Royal Society B, are ageless.

Co-author Christine Köppl of the University of Oldenburg’s animal physiology and behavior group told Seeker “an ageless ear is possible if the regenerative mechanisms can be kept going.”

That is what she and her colleagues observed in their test subjects: seven barn owls named Weiss, Grün, Rot, Lisa, Bart, Ugle, and Sova. The owls were all hatched in captivity and lived in aviaries.

The researchers divided the owls into two groups based on their respective ages. The owls in the young group were less than 2 years old, whereas the old owls were 13–17 years old. The scientists then tested each owl on its ability to hear frequencies of 0.5, 1, 2, 4, 6.3, 10, and 12 kilohertz.

The scientists trained the owls to travel from one perch to another whenever the birds heard a tone, which lasted for just an instant. Upon successful completion of the tasks, the birds received tasty food rewards. To minimize training effects, the birds were tested separately and the sequence of the various frequencies was randomized for each owl.

In addition to comparing the hearing abilities of young versus old owls, the scientists also tracked the auditory sensitivity of Weiss during his impressive lifetime. This owl lived to be 23, well beyond the typical barn owl lifespan, which is just 4 years in the wild.

All of the tests demonstrated that the owls’ hearing sensitivity was not affected by age. The findings are consistent with prior research that found birds, fish, and amphibians have the capacity to regenerate lost “hair” cells in their hearing sensory organ known as the basilar papilla. The hairs are actually long, flexible organelles that help to convert sound vibrations into electrical signals that travel to the brain along the auditory nerve.

“The regeneration mechanisms, and therefore their benefits, are likely present in all bird species,” senior author Ulrike Langemann told Seeker. “The amazing thing is that the majority of small bird species are rather short-lived, and thus will never really benefit from a preservation of auditory sensitivity at old age.”

Barn owls are considered one of natures super predators because of there silent flight and amazing hearing.
Mammals, including humans, have only a limited capacity to regenerate these hair cells when they are lost not only by aging, but also by injury or disease. According to the National Institutes of Health, more than 90 percent of hearing loss occurs when either hair cells or auditory nerve cells are destroyed.

Langemann and colleagues believe that at some point in mammal evolution, the ability to fully regenerate hair cells was lost.

“The current view is that, unfortunately, the genetic switch for the inner ear of mammals is in the off mode,” Köppl explained.

For barn owls, it appears that natural selection highly favored retention of their hair cell regeneration mechanisms. Lead author Bianca Krumm, also from the University of Oldenburg, said barn owls are predominantly nocturnal hunters with fairly large broods for a bird of their size. Most are between 13–15 inches in length. Females cannot leave their nests within the first five days of their chicks hatching because they must keep their otherwise unprotected offspring sufficiently warm.

“Male barn owls may thus face the job of catching about 30 to 40 mice per night for the family, independent of nocturnal lighting conditions,” Krumm said. “Thus ‘hunting by ear only’ must have been the solution. This includes sensitivity as well as amazing sound localization abilities. Indeed, scientists have shown that a tame barn owl will catch a prey item in complete darkness.”

Aside from their ageless ears, barn owls possess superior hearing to that of humans due to the parabolic shape of the facial disc, the concave collection of feathers on the bird’s heart-shaped face that functions like a satellite dish.

“The parabolic effect of the barn owl’s facial disc improves the sensitivity roughly by a factor of 10 in intensity compared to our human auditory sensitivity,” Langemann said, adding that if tiny headphones are placed directly in the ears of barn owls, their hearing is reduced to that of other bird species.

Barn owl ears are entirely covered with feathers, which is thought to protect the ears and to help reduce air drag when the birds are in flight.

Co-author Georg Klump said the researchers are investigating how different pathologies affect aging mammalian inner ears. They are also hoping to learn more about how barn owls locate prey so accurately using their sense of hearing.

“We are biologists and firmly believe that animals can teach us amazing things,” he said. “Different animals may indicate solutions for some of the many problems related to our modern, but aging, society.”

Read more at Seeker

Jellyfish Sleep, and Now Scientists Wonder If Plants and Bacteria Sleep Too

Close-ups of Cassiopea jellyfish.
Jellyfish lack ears, eyes, a nose, a heart, bones, and a brain. In fact, they don’t even have a head. Their states of being, as they float and pulse rhythmically in water, have therefore mostly been unknown.

Despite the fact that jellyfish lack a centralized nervous system, new research provides strong evidence that these soft-bodied marine organisms sleep. The findings, published in the journal Current Biology, have scientists reevaluating what sleep is and what it does.

“Some people probably think that a brain is needed for a sleep behavior to exist, especially those scientists that focus on the sleep states of mammals,” Michael Abrams of Caltech, who co-led the study with his Caltech colleague Ravi Nath, told Seeker.

“Though there are anecdotal observations that suggest some species don’t sleep, I do not know of any animal that has been fully interrogated that has been proven not to sleep,” he added.

Nath and fellow researchers from three Caltech laboratories — headed up respectively by Paul Sternberg, Viviana Gradinaru, and Lea Goentoro — decided in this case to investigate Cassiopea, aka the Upside-Down Jellyfish. This primitive genus essentially spends its entire life sitting upside down on the ocean floor, pulsating every few seconds.

Three criteria must be met in order for an organism to be considered as “sleeping.” First, it must demonstrate a period of reduced activity. To test this in the jellyfish, the researchers used cameras to continuously monitor the marine dwellers in tanks. The footage revealed that jellyfish go through periods of inactivity at night, only pulsing about 39 times per minute, compared to about 58 times per minute during the day.

“During the jellyfish sleep-like state, we see a reduced number of pulses, and we also see an increase in the frequency and length of pause events,” co-lead author Claire Bedbrook told Seeker.
“Pause events are where the jellyfish stop pulsing altogether for 4–20 seconds. These pause events are rarely seen during the day, when the jellyfish are in their more active state.”

The second criteria for sleep is decreased response to otherwise-arousing stimuli. To test this in the jellyfish, the scientists put a jellyfish on a platform higher up in the tank, and pulled the platform out from underneath the animal once it showed signs of quiescence.

Normally, an alert jellyfish would immediately swim to the bottom of the tank, but the jellyfish in the sleep state floated in the water for up to five seconds before “waking up” and re-orienting itself. This would be like a person sleeping, having a cover pulled off, and then gradually waking up and reacting to the change.

The third and final criteria for sleep is that the organism must show an increased sleep drive when it is deprived of this presumably more restful state.

To test this in the Cassiopea individuals, the researchers pulsed water at them every 10 seconds for 20 minutes, effectively “poking” them to keep them awake. The scientists later observed that the squirted jellyfish were more likely to fall into the sleep-like state during the day, when they would normally be active.

All of the new evidence then supports that jellyfish do indeed sleep, or at least exhibit a sleep-like state. Melatonin, a compound known to promote sleep in humans and other animals, did the same to the jellyfish, the scientists discovered.

Clearly sleep is beneficial to animals, including jellyfish. Nath suggested “that sleep is serving as a period of consolidated energy conservation.” Abrams added, “We see that the jellyfish need sleep for them to behave normally, and this indicates an important role for metabolism.”

As for what happens internally to the jellyfish when they sleep, no one is sure at present. It has not been ruled out that jellyfish dream, for example.

“If jellyfish dream, what would they dream about?” Abrams mused. “For us to approach this question, we would need to directly record the neural activity during the day and night. Though it may be impossible to definitively say that they dream, it would be interesting to see if they have sleep phases, perhaps similar to the neural activity oscillations seen during REM.”

Multiple Cassiopea jellyfish. The animals prefer to sit upside down on the floor of the water column.
Based on this and prior studies, it is possible that Earth’s first multicellular organisms exhibited sleep — or something like it — as well as other behavioral states.

Nath mentioned that jellyfish are among the first animals to develop neurons, so it could be that sleep first evolved with the emergence of these specialized cells that transmit nerve impulses.

Alternatively, sleep may be tied to other biological factors, opening up the possibility that plants and bacteria go through sleep-like states too.

“Plants certainly have different states,” Nath said.

Earlier research has even found that plant leaves can move in response to a biological clock. Some researchers refer to these and other circadian plant phenomena, like the closing of flowers, as “sleep movements.”

“Just like plants and other multicellular organisms, bacteria have different states,” Nath noted,  “although I do not know if they sleep, as there is no detailed study showing that bacteria exhibit a sleep state.”

Read more at Seeker

Mass Extinctions on Earth Coincided With Out-of-Whack Carbon Cycles

Fossil skeleton of a Pteradactyl, from the British Museum's collection
Previous mass extinctions in Earth’s history can illuminate how much carbon human civilization can pump into the environment before risking a catastrophic climate change — and that point may be coming up within a century.

That’s the conclusion of Daniel Rothman, a geophysicist at the Massachusetts Institute of Technology, who built a database of fossil records going back half a billion years. Rothman found the periods in which large percentages of existing species died off coincided with big swings in the carbon isotopes found in those records, suggesting the planet’s carbon cycle was out of whack.

“It implies changes in the carbon cycle are likely both an indication of some kind of serious change and possibly a player in amplifying those changes,” Rothman told Seeker.

In a stable environment, carbon ebbs and flows from organic materials. Carbon dioxide fuels photosynthesis in plants, which store it as they grow; when they die and decay, it’s released back into the skies and the oceans.

But human civilization has been pumping more carbon into the environment by burning carbon-rich fossil fuels like coal, oil, and natural gas. On the current trajectory, the oceans are expected to absorb at least another 300 billion tons of carbon by 2100 — an amount that could end up producing long-term changes to the environment, Rothman concluded.

Sedimentary rocks at Meishan, China contain signatures of a disturbance in the carbon cycle immediately preceding Earth's greatest mass extinction.
Passing the threshold Rothman has calculated could mean abrupt environmental change — abrupt in biological and geochemical terms meaning within 10,000 years, Rothman said.

“It’s not that the date 2100 is a magic date,” he said. “It’s that the projection of the amount of carbon that will have been added by anthropogenic means — fossil fuel burning — for the most part suggest that 300 gigaton limit will have been surpassed by end of the century. But it may happen sooner. The question in the end is: What happens next?”

The study was published Wednesday in the research journal Science Advances.

Rothman isn’t alone in warning of a potential extinction. Some scientists argue a sixth such event is under way already, with about two species a year disappearing and thousands seeing their populations and ranges shrink. And scientists have long warned that an increase in global average temperatures beyond 2 degrees Celsius (3.6 degrees Fahrenheit) could have catastrophic consequences.

Read more at Seeker

Sep 20, 2017

Bite force research reveals dinosaur-eating frog

South American horned frog -- Pacman frog -- has tremendous bite force.
Scientists say that a large, now extinct, frog called Beelzebufo that lived about 68 million years ago in Madagascar would have been capable of eating small dinosaurs.

The conclusion comes from a study of the bite force of South American horned frogs from the living genus Ceratophrys, known as Pacman frogs for their characteristic round shape and large mouth, similar to the video game character Pac-Man. Due to their attractive body colouring, voracious appetite, and comically huge heads, horned frogs are very popular in the international pet trade.

Published today in the Nature journal Scientific Reports, the scientists from University of Adelaide, California State Polytechnic University -- Pomona, University of California -- Riverside and UCL, University College London found that living large South American horned frogs have similar bite forces to those of mammalian predators.

"Unlike the vast majority of frogs which have weak jaws and typically consume small prey, horned frogs ambush animals as large as themselves -- including other frogs, snakes, and rodents. And their powerful jaws play a critical role in grabbing and subduing the prey," says Dr Marc Jones, researcher at the University of Adelaide's School of Biological Sciences and honorary researcher at the South Australian Museum.

The study found that small horned frogs, with head width of about 4.5cm, can bite with a force of 30 newtons (N) or about 3 kg or 6.6 lbs. A scaling experiment, comparing bite force with head and body size, calculated that large horned frogs that are found in the tropical and subtropical moist lowland forests of South America, with a head width of up to 10 cm, would have a bite force of almost 500 N. This is comparable to reptiles and mammals with a similar head size.

"This would feel like having 50 litres of water balanced on your fingertip," says Professor Kristopher Lappin, Professor of Biological Sciences at California State Polytechnic University -- Pomona.

Based on their scaling relationship, the scientists estimated the bite force of the giant extinct frog Beelzebufo -- which is in many ways similar to living horned frogs -- may have had a bite up to 2200 N, comparable to formidable mammalian predators such as wolves and female tigers.

"At this bite force, Beelzebufo would have been capable of subduing the small and juvenile dinosaurs that shared its environment," says Dr Jones.

The scientists measured bite force using a custom-made force transducer, a device which accurately measures the force applied to two plates covered with leather when an animal bites them.

"This is the first time bite force has been measured in a frog," says Professor Lappin. "And, speaking from experience, horned frogs have quite an impressive bite, and they tend not to let go. The bite of a large Beelzebufo would have been remarkable, definitely not something I would want to experience firsthand."

Read more at Science Daily

Unique type of object discovered in our solar system

This artist's impression shows the binary asteroid 288P, located in the main asteroid belt between the planets Mars and Jupiter. The object is unique as it is a binary asteroid which also behaves like a comet. The comet-like properties are the result of water sublimation, caused by the heat of the Sun. The orbit of the asteroids is marked by a blue ellipse.
With the help of the NASA/ESA Hubble Space Telescope, a German-led group of astronomers have observed the intriguing characteristics of an unusual type of object in the asteroid belt between Mars and Jupiter: two asteroids orbiting each other and exhibiting comet-like features, including a bright coma and a long tail. This is the first known binary asteroid also classified as a comet. The research is presented in a paper published in the journal Nature today.

In September 2016, just before the asteroid 288P made its closest approach to the Sun, it was close enough to Earth to allow astronomers a detailed look at it using the NASA/ESA Hubble Space Telescope.

The images of 288P, which is located in the asteroid belt between Mars and Jupiter, revealed that it was actually not a single object, but two asteroids of almost the same mass and size, orbiting each other at a distance of about 100 kilometres. That discovery was in itself an important find; because they orbit each other, the masses of the objects in such systems can be measured.

But the observations also revealed ongoing activity in the binary system. "We detected strong indications of the sublimation of water ice due to the increased solar heating -- similar to how the tail of a comet is created," explains Jessica Agarwal (Max Planck Institute for Solar System Research, Germany), the team leader and main author of the research paper. This makes 288P the first known binary asteroid that is also classified as a main-belt comet.

Understanding the origin and evolution of main-belt comets -- comets that orbit amongst the numerous asteroids between Mars and Jupiter -- is a crucial element in our understanding of the formation and evolution of the whole Solar System. Among the questions main-belt comets can help to answer is how water came to Earth. Since only a few objects of this type are known, 288P presents itself as an extremely important system for future studies.

The various features of 288P -- wide separation of the two components, near-equal component size, high eccentricity and comet-like activity -- also make it unique among the few known wide asteroid binaries in the Solar System. The observed activity of 288P also reveals information about its past, notes Agarwal: "Surface ice cannot survive in the asteroid belt for the age of the Solar System but can be protected for billions of years by a refractory dust mantle, only a few metres thick."

From this, the team concluded that 288P has existed as a binary system for only about 5000 years. Agarwal elaborates on the formation scenario: "The most probable formation scenario of 288P is a breakup due to fast rotation. After that, the two fragments may have been moved further apart by sublimation torques."

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