Culture

Ordered and variable animal behaviours emerge to explore and adapt to the environment. They are generally considered as the combination of a series of stereotyped motor primitives. However, how the nervous system shapes the dynamics of motor sequences remains to be solved.

In a study published in eLife, Prof. WEN Quan from School of Life Sciences, University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) has proposed the algorithms and circuit mechanisms for the robust and flexible motor states of nematodes during escape responses.

Prof. WEN's group investigated nematode Caenorhabditis elegans (C. elegans) on the neural circuit mechanisms of how robust and flexible the motor sequences are generated.

C. elegans are ideal subjects for their simple yet fully functional neural system with only 302 neurons, approximately 6400 chemical synapses and 890 electrical synapses. Early in the 1980s, the coupling image of neural networks were reconstituted at the synapse scale by the electron microscope, laying a solid foundation for the research on the neural circuit. Besides, optical manipulation and detection are easily conducted considering C. elegans' overall transparent bodies.

Potential threats like mechanical or thermal stimuli robustly trigger escape responses comprised of stereotyped motor modules including forward movement, backward movement and turning movement. However, the sequence and timing of actions of every module vary from each other.

With the help of optogenetic technology, calcium image and computational models, the researchers discovered that the excitatory feedforward coupling accounts for certain motor sequences robustly triggered by stimuli, while a winner-take-all operation via mutual inhibition between motor modules realizes the flexible alteration of different motor patterns. Also, the plasticity of short-term synapses and the intrinsic noise of the nervous system play an important role in the sequence and timing of motor patterns.

Applying the coupling image of neural networks of C. elegans and molecular biological methods, the researchers further proved that electrical synapses contribute to feedforward coupling, whereas glutamatergic synapses contribute to inhibition between modules through glutamate-gated chloride expressed by downstream neurons.

The study opens more possibilities to understand the mechanisms of motor manipulation of advanced organisms, and sheds new light on the design of the next generation of brain-inspired intelligence.

Staring at a deep red light for three minutes a day can significantly improve declining eyesight, finds a new UCL-led study, the first of its kind in humans.

Scientists believe the discovery, published in the Journals of Gerontology, could signal the dawn of new affordable home-based eye therapies, helping the millions of people globally with naturally declining vision.

In the UK there are currently around 12 million people aged over 65: in 50 years this will increase to around 20 million and all will have some degree of visual decline because of retinal ageing.

Lead author, Professor Glen Jeffery (UCL Institute of Ophthalmology) said: "As you age your visual system declines significantly, particularly once over 40.

"Your retinal sensitivity and your colour vision are both gradually undermined, and with an ageing population, this is an increasingly important issue.

"To try to stem or reverse this decline, we sought to reboot the retina's ageing cells with short bursts of longwave light."

In humans around 40 years-old, cells in the eye's retina begin to age, and the pace of this ageing is caused, in part, when the cell's mitochondria, whose role is to produce energy (known as ATP) and boost cell function, also start to decline.

Mitochondrial density is greatest in the retina's photoreceptor cells, which have high energy demands. As a result, the retina ages faster than other organs, with a 70% ATP reduction over life, causing a significant decline in photoreceptor function as they lack the energy to perform their normal role.

Researchers built on their previous findings in mice, bumblebees and fruit flies, which all found significant improvements in the function of the retina's photoreceptors when their eyes were exposed to 670 nanometre (long wavelength) deep red light.

"Mitochondria have specific light absorbance characteristics influencing their performance: longer wavelengths spanning 650 to 1000nm are absorbed and improve mitochondrial performance to increase energy production," said Professor Jeffery.

The retina's photoreceptor population is formed of cones, which mediate colour vision and rods, which provide peripheral vision and adapt vision in low/dim light.

For the study, 24 people (12 male, 12 female), aged between 28 and 72, who had no ocular disease, were recruited. All participants' eyes were tested for the sensitivity of their rods and cones at the start of the study. Rod sensitivity was measured in dark adapted eyes (with pupils dilated) by asking participants to detect dim light signals in the dark, and cone function was tested by subjects identifying coloured letters that had very low contrast and appeared increasingly blurred, a process called colour contrast.

All participants were then given a small LED torch to take home and were asked to look into* its deep red 670nm light beam for three minutes a day for two weeks. They were then re-tested for their rod and cone sensitivity

Results

Researchers found the 670nm light had no impact in younger individuals, but in those around 40 years and over, significant improvements were obtained.

Cone colour contrast sensitivity (the ability to detect colours) improved by up to 20% in some people aged around 40 and over. Improvements were more significant in the blue part of the colour spectrum that is more vulnerable in ageing.

Rod sensitivity (the ability to see in low light) also improved significantly in those aged around 40 and over, though less than colour contrast.

Professor Jeffery said: "Our study shows that it is possible to significantly improve vision that has declined in aged individuals using simple brief exposures to light wavelengths that recharge the energy system that has declined in the retina cells, rather like re-charging a battery.

"The technology is simple and very safe, using a deep red light of a specific wavelength, that is absorbed by mitochondria in the retina that supply energy for cellular function.

"Our devices cost about £12 to make, so the technology is highly accessible to members of the public."

In a system with self-replicating molecules -previously shown to have the capability to grow, divide and evolve - chemists from the University of Groningen have now discovered catalytic capabilities that result in a basic metabolism. Furthermore, they linked a light-sensitive dye to the molecules, which enabled them to use light energy to power growth. These findings, which bring artificial life one step closer, were published simultaneously in the journals Nature Chemistry and Nature Catalysis on 26 June.

Ten years ago, Sijbren Otto, Professor of Systems Chemistry at the University of Groningen's Stratingh Institute for Chemistry, discovered a new mechanism for self-replication: small peptide-containing molecules in solution form rings that subsequently form growing stacks. When a stack breaks, both halves start to grow again. Furthermore, the growth of stacks depletes the number of rings in solution and this, in turn, stimulates the formation of new rings from the building blocks. The system could also 'mutate' when different building blocks were added.

Stunning discovery

This system, which arose spontaneously, is a form of artificial proto-life. 'The definition of life is complex but in general, life should have three basic properties,' explains Otto. 'The first is replication, and this happens in our system. The second is metabolism, which should create building blocks from materials in the environment. And the third is compartmentalization, which separates the living organism from its surroundings.' Finally, such organisms should develop a fourth, more advanced property, which is the ability to evolve and invent.

Otto and his team set out to make changes to their molecules in order to add catalytic capabilities. 'However, when we started the project, we made a stunning discovery. Without requiring any changes, the system already showed catalysis; we just hadn't noticed this before.' The stacks grow from rings made up of six building blocks. These rings are formed by combining the building blocks of smaller rings that are made up of three or four building blocks.

Evolution

'It turned out that the stacks of rings catalyse the formation of the smaller rings,' says Otto. Further analysis showed that catalysis of this reaction requires the presence of two specific amino acid residues (two lysine residues). 'Neither the building blocks nor the separate rings have catalytic abilities but the stacks do. So, we assume that in these stacks, a 3D configuration of these lysine residues arises that acts as the catalytic centre, just like proteins shape active sites by placing amino acid residues in highly specific arrangements,' explains Otto. Thus, in the structures that emerge as a result of their ability to self-replicate, amino acids become organized in such a way that they can act as catalysts.

The stacks are also capable of retro-aldol catalysis, a well-known reaction that is often used to benchmark catalyst design efforts. 'Interestingly, our stacks, which were not designed to have catalytic capabilities, were as efficient as the best-designed catalysts we know.' Finding out that the same stacks can catalyse two very different reactions is interesting. Many enzymes have this ability, which gives evolution a chance to develop something new.

Metabolism

In a second study, a photosensitive dye was added. 'Guille Monreal, one of my PhD students, read that such a dye could stimulate the formation of reactive singlet oxygen in amyloid peptides. As reactive oxygen drives important steps in ring formation, he wanted to see if this would speed up the formation of rings.' Two different dyes were found that indeed speed up ring formation when exposed to light, but only when they were bound to the stacks. 'The dyes appeared to act as cofactors for the stacks, just like modern-day proteins use cofactors for their catalysis,' says Otto. When bound to the replicating fibres, the dye can use energy from light to create reactive singlet oxygen and thereby increase the formation of new rings.

Both the spontaneous catalysis by the stacks and the catalysis mediated by the cofactor result in a kind of metabolism that is linked to replication. 'It is not yet the kind of metabolism you see in living organisms,' explains Otto. 'In our system, catalysis merely speeds up reactions that would occur slowly without help. In life, metabolism also drives reactions that would otherwise not occur.'

Artificial life

However, Otto's artificial system shows both replication and a primitive form of metabolism. 'Furthermore, from this point, compartmentalization is a relatively small step.' So, is he close to seeing artificial life evolve in his test tubes? 'Not quite,' admits Otto. 'That would require the system to be capable of open-ended evolution, which means it can evolve capabilities that are not present in the system. And we have as yet no clear idea how to accomplish that. But our system appears to be a sound basis from which we may get there.'

Simple Science Summary

Ten years ago, Sijbren Otto, Professor of Chemistry at the University of Groningen, discovered self-replicating molecules that spontaneously formed rings, which then organized into stacks. These growing stacks were able to divide by breaking in half after which each half continues to grow. This system looks like a primitive form of life. Otto and scientists from his research team now discovered that the stacks act as catalysts, which speed up the formation of new rings from simple building blocks. Furthermore, when a light-sensitive dye is added and binds to the stacks, it will use the energy from light to produce reactive oxygen, which also speeds up the formation of new rings. Both reactions are a simple kind of metabolism. This means that these molecules do not just grow and multiply, they can also stimulate the production of their own building blocks. This brings them one step closer to a man-made system that would qualify as 'artificial life'.

WASHINGTON, DC (June 26, 2020) - When work requirements for a federal food safety-net program start again, many low-income Americans will lose benefits - and Black adults will be hardest hit, according to a study published today. In addition, some disabled people will lose these crucial food assistance benefits.

The authors point out that the loss of food assistance would damage the health of low-income people, who suffer from high rates of COVID-19 and other serious health conditions.

"The COVID-19 pandemic has resulted in record rates of unemployment. SNAP benefits are critical to help people who have lost work get the food they need," said lead author Erin Brantley, PhD, MPH, a senior research associate at the George Washington University Milken Institute School of Public Health (Milken Institute SPH). "When work requirements for SNAP start again, history shows we can expect to see a disproportionate impact on black families."

Work requirements for Supplemental Nutritional Assistance Program (SNAP), formerly called the food stamp program, are temporarily paused under the Families First Coronavirus Response Act but are set to resume when the federal public health emergency ends. Separate from this action, the Trump administration issued a new rule to limit the ability that states traditionally have had to waive SNAP work requirements when unemployment is high, although a federal court has temporarily stopped implementation.

The study is the first to find that SNAP work requirements lead more Black adults to lose food assistance compared to white adults. It is also the first published research to show that SNAP work requirements cause disabled adults to lose benefits. Although SNAP work requirements exempt some people with disabilities, others may not qualify for an exemption, despite facing substantial health challenges. In some cases, disabled people may lose SNAP benefits because they cannot navigate the paperwork requirements, the authors point out.

Brantley and her colleagues at the Milken Institute SPH analyzed the impact of the requirement that low-income Americans prove that they are working - or lose SNAP benefits. The study examined what happened when many states put work requirements for SNAP into place between 2013 and 2017. The researchers found that:

Food stamp work requirements for adults aged 18 to 49 led to a 21 percent drop in participation in the program overall;

Black adults experienced a 23 percent loss in food assistance during that time, much larger than the 16 percent decline for white adults, likely because black workers have fewer work prospects;

Even though the law exempts some with disabilities, there was a significant 7.8 percent drop in participation for these Americans.

The authors point out that although work requirements are paused during the public health emergency, the economic fall-out, high rates of unemployment and food insecurity could last long after the crisis is declared over.

"Our study suggests that even when the economy was strong such work requirements created disparities that harmed low-income people, especially in Black communities and people with disabilities," said Leighton Ku, director of the Center for Health Policy Research at Milken Institute SPH and co-author of the study. "The harm will be far worse when jobs are scarce during and after the COVID-19 pandemic, since high unemployment is expected to persist."

The findings also have implications for health insurance coverage. The Trump administration has encouraged states to introduce work requirements to Medicaid. Although federal courts have blocked implementation of Medicaid work requirements in some states, several states have continued to develop plans for new policies.

SNAP provides an estimated 37 million Americans with electronic vouchers to help pay for groceries. Low-income people who receive SNAP benefits have improved food security and that leads to better health, Ku and Brantley say.

What The Study Did: This study examined the worldwide trends of thyroid cancer from 1990 to 2017 according to geographic location, sex, age and socioeconomic factors.

Authors: Jun Lyu, Ph.D., of the First Affiliated Hospital of Jinan University in Guangzhou, China, and ZhiJun Dai, Ph.D., of Zhejiang University in Hangzhou, China, are the corresponding authors.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2020.8759)

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflicts of interest and financial disclosures, and funding and support.

What The Study Did: The clinical characteristics and outcomes in patients with multiple sclerosis who contract COVID-19 are described in this observational study, which identifies factors associated with COVID-19 severity.

Authors: Celine Louapre, M.D., of the Sorbonne Universite in Paris, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamaneurol.2020.2581)

Editor's Note: The article includes conflicts of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflicts of interest and financial disclosures, and funding and support.

Indium nitride is a promising material for use in electronics, but difficult to manufacture. Scientists at Linköping University, Sweden, have developed a new molecule that can be used to create high-quality indium nitride, making it possible to use it in, for example, high-frequency electronics. The results have been published in Chemistry of Materials.

The bandwidth we currently use for wireless data transfer will soon be full. If we are to continue transmitting ever-increasing amounts of data, the available bandwidth must be increased by bringing further frequencies into use. Indium nitride may be part of the solution.

"Since electrons move through indium nitride extremely easily, it is possible to send electrons backwards and forwards through the material at very high speeds, and create signals with extremely high frequencies. This means that indium nitride can be used in high-frequency electronics, where it can provide, for example, new frequencies for wireless data transfer", says Henrik Pedersen, professor of inorganic chemistry at the Department of Physics, Chemistry and Biology at Linköping University. He has led the study, which was recently published in Chemistry of Materials.

Indium nitride consists of nitrogen and a metal, indium. It is a semiconductor and can therefore be used in transistors, on which all electronic devices are based. The problem is that it is difficult to produce thin films of indium nitride. Thin films of similar semiconductor materials are often produced using a well-established method known as chemical vapour deposition, or CVD, in which temperatures between 800 and 1,000 degrees Celsius are used. However, indium nitride breaks down into its constituents, indium and nitrogen, when it is heated above 600 degrees Celsius.

The scientists who conducted the present study have used a variant of CVD known as atomic layer deposition, or ALD, in which lower temperatures are used. They have developed a new molecule, known as an indium triazenide. No one had worked with such indium triazenides previously, and the LiU researchers soon discovered that the triazenide molecule is an excellent starting material for the manufacture of thin films. Most materials used in electronics must be produced by allowing a thin film to grow on a surface that controls the crystal structure of the electronic material. The process is known as epitaxial growth. The researchers discovered that it is possible to achieve epitaxial growth of indium nitride if silicon carbide is used as substrate, something that was not previously known. Furthermore, the indium nitride produced in this way is extremely pure, and among the highest quality indium nitride in the world.

"The molecule that we have produced, an indium triazenide, makes it possible to use indium nitride in electronic devices. We have shown that it is possible to produce indium nitride in a manner that ensures that it is sufficiently pure to be described as a true electronic material", says Henrik Pedersen.

The researchers discovered another surprising fact. It is generally accepted among those who use ALD that the molecules should not be allowed to react or be broken down in any way in the gas phase. But when the researchers changed the temperature of the coating process, they discovered that there is not just one, but two, temperatures at which the process was stable.

"The indium triazenide breaks down into smaller fragments in the gas phase, and this improves the ALD process. This is a paradigm shift within ALD - using molecules that are not fully stable in the gas phase. We show that we can obtain a better final result if we allow the new molecule to break down to a certain extent in the gas phase", says Henrik Pedersen.

The researchers are now examining similar triazenide molecules with other metals than indium, and have obtained promising results when using these to produce molecules for ALD.

More than ten years ago, large geometric earthworks found in the southwestern parts of the Amazon, called geoglyphs, were reported in the global scientific news. A pre-colonial civilization unknown to scholars that built geometric ceremonial centers and sophisticated road systems. This civilization flourished in the rainforest area 2,000 years ago. The discovery radically altered the prevailing notion of the pristine Amazon rainforest. The research of an interdisciplinary Finnish-Brazilian team continues in the region with the support of the Academy of Finland. Recent findings show that large ancient construction projects not only shaped the landscape, but civilization has also impacted the diverse construction of rainforest.

The research team's latest article "Domestication in Motion" has been published in the journal Environmental Archeology last week. The article shows that in addition to the cultivation of manioc, maize and squash, the protection, care and planting of several trees were important for the food supply of the region's Indigenous peoples, says research director Professor Martti Pärssinen. In particular, Brazilian nut and palm trees with protein-rich fruits are common in samples from geoglyphic sites. They show the pre-colonial diet of the geoglyphic ceremonial sites.

The article also describes how tree domestication was not a linear process in Amazon conditions, as wild forms of plants could also be protected. During the archaeological excavations wild and domesticated forms of peach palm fruit were found, among other plants. On the other hand, especially Brazilian nut trees as well as many palm trees, which are vital for both their fruits and palm kernels, were domesticated in the rainforest area for human consumption. Their fruits are clearly larger than they were 2,000 years ago.

A unlinear process of domestication is evident, as both wild and domesticated peach palm trees are still well known by Indigenous peoples in the state of Acre, and the latter have spread to a very large area across the Amazon, says Pirjo Kristiina Virtanen, assistant professor involved in the project.

Human impact on the Amazon rainforest stand has been significant, and therefore there is no such thing as virgin rainforest. On the other hand, the study shows that Indigenous peoples of the Amazon have been able to use their environment in a sustainable way by domesticating certain plants while protecting and respecting it. There is no indication that large areas of forest would have been deforested.

These new findings argue against the idealistic notion of the pristine Amazon rainforest. At the same time, however, it highlights how Indigenous peoples utilize wild plants while domesticating certain plants for humans' use. The relationship between the peoples of the Amazon and forest has been proved sustainable. It should be explored further and lessons could be learned from this.

The authors of the article are from the University of Helsinki. Martti Pärssinen, Professor Emeritus leads the project and Pirjo Kristiina Virtanen, Assistant Professor of Indigenous Studies, has worked with the Indigenous peoples of the region. In addition to them, the authors were Brazilian palm researcher Evandro Ferreira and paleoecologist Alceu Ranzi from the Federal University of Acre. The Finnish Cultural and Academic Institute in Madrid has also contributed to the project. In Brazil the research was authorised by Instituto do Patrimônio Histórico e Artístico Nacional (IPHAN) and Fundação Nacional do Índio (FUNAI).

The blood circulatory system serves as critical infrastructure for mass transportation of nutrients and facilitates the exchange of gaseous and waste products from organs in the human body. These blood vessels are subjected to constant exposure to the hydrodynamic pressure of blood flow, as well as the contracting and relaxing rhythm exerted by tissues surrounding it. The exposure to these stimuli can trigger a cascade of cellular responses that may give rise to adverse conditions such as thrombosis and inflammation in blood vessels.

These cellular responses to events are known as mechanotransduction - the process of converting mechanical signals into chemical signals in the body. Although researchers have managed to engineer disease models that mimic various impairments in blood vessels, the ability to incorporate simultaneous shear stress from blood flow and stretch stress was still deemed as challenging to replicate.

Researchers from Keio University (Keio U) Onoe Research Group collaborated with Singapore University of Technology and Design's (SUTD) Soft Fluidics Lab to develop and fabricate an extracellular matrix (ECM)-based microchannel that enables to provide mechanical stimuli due to perfusion and stretching simultaneously (refer to image). This straightforward method allowed the researchers to make a complex network of microchannels in an ECM that resembled human tissues by sacrificial molding.

In this approach, the mold was first patterned with bifurcations and cascading dimensions as low as 0.2 mm in width. A commercially and ubiquitously available fused deposition modeling (FDM) 3D printer was used to print the sacrificial mold made with polyvinyl alcohol (PVA). Unlike a well-establish method such as replica molding where multiple steps of assembly and alignment were required to create microchannel with 3D geometry, sacrificial molding enabled the rapid fabrication of microchannels in various matrices. The mold was embedded entirely in an ECM (gelatin), cured with transglutaminase; sealing, alignment, or stacking were not necessary when making the platform for blood vessels and surrounding tissue.

"Since the PVA mold is removable in water, the process of fabrication was entirely completed using only water. This is important to ensure the biocompatibility of the fabricated microchannels," said Jason Goh, a Ph.D. scholar at SUTD.

"Sacrificial molding of a fused deposition modeling 3D-printed mold offers wide freedom of design and potentiates the fabrication of more physiological relevant platform," added Assistant Professor Michinao Hashimoto from SUTD.

Human endothelial cells were readily cultured on the surface of the microchannel to form a tube mimicking blood vessels. The hallmark behavior of blood vessels, such as its pulsatile flow, was successfully achieved under conditions of perfusion and stretch. This blood vessel platform served to broaden the spectrum of applicability of current vascular in vitro models to investigate pathological conditions in a more physiologically relevant manner.

"We successfully demonstrated to engineer substitutes for blood vessels with sufficient mechanical strength to withstand the applied fluid pressure and stretching present in the human body. The platform will be useful to understand the mechanisms of vascular diseases," said Azusa Shimizu, the lead author and an MSc student, and Associate Professor Hiroaki Onoe from Keio U, Japan.

The research work has been published and featured prominently in the inside cover of Lab on a chip, the top journal covering original work related to the miniaturization below the microscale and at the interface between technological advancements and impactful applications. Azusa Shimizu (Keio U) collaborated with Jason Goh (SUTD) and Shun Itai (Keio U). Other senior researchers of the project include Dr. Shigenori Miura from the University of Tokyo.

It's not often that scientists are able to find tuff in continental sedimentation, but this was accomplished in the PreUrals region by Kazan Federal University, Borisyak Institute of Paleontology, and Institute of Geology (the latter two are parts of the Russian Academy of Sciences). This was a first such finding on the territory of European Russia. Radioisotopic analysis was conducted by Boise State University.

"We calculated the precise age of the upper layers of the continental formation of European Russia. The age is 253.95 million years, and this helped us to directly compare sea and continental sedimentation, something that would be impossible with the sole use of paleontological methods. This is a first opportunity to directly compare fauna associations of terrestrial vertebrates in Russia, Southern Africa, Greenland, and India. Thus, we can determine the length of thaws and glaciations in European Russia in late Permian," says co-author Vladimir Silantiev, Chair of the Department of Paleontology and Stratigraphy at Kazan Federal University.

Tuff includes microscopic particles of zircon, which makes it possible to determine the absolute age of rocks. After seven years of work, the key finding was made near the Vetluga River in Northern Russia. Volcanic tuff from thousands of kilometers away ended up here. Continental platforms are usually not conducive to preserving such material for millions of years because of intense geological processes, but in this case, the researchers were in luck.

As the "king of beasts," majestic lions have been used as a symbol of courage, nobility and strength by rulers for over 6000 years. A lion became the symbol of a Norwegian king at least as early as 1280. It still stands proudly on Norway's Coat of Arms.

Wild lions have likely never made their way to Norway, but European cave lions were once found as far north as Denmark.

Lions were once far more widespread than they are now, with several subspecies of lions dividing the world between them. They were found in much of Europe and Asia including the Middle East, in Africa, North America and maybe South America.

Today, the lion is considered a vulnerable species, and is found only in relatively isolated pockets of Africa and - just barely still - in India.

Filling in the lions' family tree

Experts disagree on how many subspecies exist now and have previously existed, and presumably there is significant overlap among several of them. We need to know this information to save the lions.

"We wanted to find out more about the relationships between the different groups, or populations, of lions," says Michael D. Martin at the Norwegian University of Science and Technology's (NTNU) University Museum's Department of Natural History.

An international research group has helped expand our understanding of the lion species' family tree. The results were recently presented in PNAS, the Proceedings of the National Academy of Sciences of the United States of America.

Associate Professor Martin is among the contributors. The last author is Professor Tom Gilbert from the same department. He is also head of the Centre for Evolutionary Hologenomics at the University of Copenhagen.

Tackling the whole DNA

Previously, the cave lion Panthera leo spelaea was found across much of Eurasia and as far as Alaska and Canada.

But cave lions died out 13 000 years ago, perhaps partly due to humans, although palaeontologists suspect that climate change played a major role. The American lion P. leo atrox suffered the same fate.

The researchers wanted to find answers to several questions.

How closely related were cave lions to today's lions?

When did cave lions and today's lions diverge?

Are some of today's lion populations more closely related to cave lions than others?

How much genetic diversity do lions have today compared to in the past?

Several groups have previously investigated mitochondrial DNA (mtDNA) when they were studying the relationships between different populations of lions. (See fact box.)

"But mtDNA is only a small part of the overall genetic material. Our group looked at all the DNA to get a more complete picture," says Gilbert.

Little interbreeding by cave lions

The research team examined two cave lions, from Siberia and Canada's Yukon. They also looked at 12 lions from populations that died out in historical times in Africa and the Middle East. In addition, they examined six lions from populations that are still extant in Africa and India.

The geographical spread of these lions corresponds very roughly to the area lions once inhabited, and where they still exist today.

"The cave lions don't appear to have mixed much with the other subspecies. We find no evidence of hybridization between the cave lions and the other groups of lions," says Gilbert.

The studies also indicate that cave lions and other lions most likely diverged about 500 000 years ago. This is in line with some previous findings, while others believe that they probably parted ways much earlier.

Two main branches

Not only the cave lions are distinct from other lions. Modern lions also show two main branches that may have diverged some 70 000 years ago.

"A northern branch includes Asian, North African and West African lions. A southern African branch includes southern, eastern and South African lions," says Martin.

This division is the same as other research groups have found by examining mitochondrial DNA (mtDNA) - up to a point. But the new study differs in several areas as well.

Studies of mtDNA have previously grouped central African lions with the northern branch, but studies of the entire DNA show that they might belong to the southern one instead.

Could help the Barbary lions

Furthermore, the North African lions, which are at least extinct in the wild, are probably more closely related to the West African lions than to the Asian lion lineage, which many scientists have believed up to now.

"This is important to know for people who may want to bring back the North African lions," says Martin.

The North African Barbary lions disappeared from the wild in the 1960s, but captive specimens may be Barbary lions, at least in part.

If these captive individuals ever need new external gene supplements to prevent inbreeding, it would probably be best to use West African lions rather than Asian ones.

Important to know what we have

Perhaps it seems a bit strange to some that several research groups are spending so much time figuring out the relationships between the different lions in the world.

"The work isn't interesting only for us geneticists and natural historians, although that's exciting enough. It's also important for people who want to conserve our lions and give them a fair chance to survive as a species outside captivity," says Gilbert.

As many as one million lions might have lived in the wild as recently as 1950. Today, a common estimate is between 20 000 and 30 000. Only 600 of the Indian lions are left.

Human activity is the main cause of the decline in most places, either directly by humans killing animals or indirectly by our species impacting their habitats.

"Some people have claimed that the Indian lions are actually African lions that were released into the wild in India and that it's therefore not as valuable to preserve them. But we've found that the Indian lions are so genetically different from the African lions that this claim can't be true," says Gilbert.

Danger of inbreeding

The research group is also finding less genetic diversity between the lions today than was found a few decades ago. This may be especially true of the geographically isolated Indian lions.

"We have fewer lions than we used to, and groups of lions are actually isolated from other groups, often due to human activity. That increases the risk of inbreeding," says Martin.

Inbreeding, which results in lions being more genetically similar, may mean that the population is more susceptible to various diseases and may not be able to reproduce. Of course, this is important to know for anyone who is involved with preserving the lions.

According to senior researcher at the Universitat Oberta de Catalunya's Internet Interdisciplinary Institute (IN3) Gender and ICT (GenTIC) research group, Milagros Sáinz, "In those cases where families have very sexist attitudes in relation to education and life, their opinions in terms of academic and other skills which boys and girls are ideally supposed to have may hold even more weight."

Despite the current lockdown being a temporary event, the researcher suggests that such circumstances may influence the decisions being made by young people with regard to their educational path in terms of their choice of courses for post-compulsory secondary or university education.

"There is a risk that young people, especially those from certain socio-economic and cultural backgrounds, will be more likely to be swayed by the opinions and experiences of their parents than they would have been prior to the health crisis," says Sáinz, who went on to add that, "They are not socializing with others, such as teachers or members of their peer groups in the same way as they were before quarantine."

In a study published in the International Journal of Social Psychology, the researcher with José Luis Martínez and Julio Meneses, also from the UOC, analysed the differences corresponding to gender in the response mechanisms of secondary school students with regard to scenarios related to academic sexism. The researchers explain that "girls are particularly likely to encounter this kind of situation, as they are more frequently faced with sexist attitudes about their abilities in science, technology, engineering and mathematics (STEM) subjects than boys."

According to the study, students whose parents had completed intermediate or higher level academic studies showed a greater predisposition to actively confronting sexist situations. "Interestingly, we observed that boys tend to use avoidance in response to scenarios of academic sexism, whereas girls are more likely to confront them or seek help from people in authority, such as teachers or family members, when it comes to this type of situation," the expert pointed out.

Boys are also affected by sexism

The study sampled 954 first-year baccalaureate students across ten schools in the metropolitan areas of Madrid and Barcelona. Sixty per cent of the students described their parents' level of academic achievement as intermediate, while 30% said that it was high and the final 10% reported a low level of education. In terms of origin, 80% of the student's parents were born in Spain.

Students were asked to complete a questionnaire in which they were presented with a series of different scenarios involving sexist attitudes towards their academic abilities and they had to state whether they would respond by: confronting the situation, asking for help or avoidance.

The students also had to indicate to what extent they agreed with five sexist statements about the academic abilities of boys and girls. In terms of their own personal experience, they also had to say whether anyone around them had ever made discouraging remarks about their abilities in STEM fields, such as mathematics, technology and physics (in the case of girls), or in languages and biology (in the case of boys).

In the words of Milagros Sáinz, "Our society tends to undervalue women's abilities with regard to highly prestigious and socially valued subjects and fields, such as science and technology. Boys, however, are used to their skills being valued above those of girls, which is also an example of sexism, albeit positive in this case, as it works in their favour."

According to the expert, this type of sexism does not mean that all boys have a greater affinity for those subject areas and they also feel frustrated and suffer its negative effects because many "do not comply with that ideal of masculinity".

The influence of parental academic achievement

In addition to gender being influential in determining the way young people tackle academic discrimination, the study also emphasizes an impact corresponding to levels of parental education.

As pointed out by Sáinz, "Gender explains the different ways of coping with academic sexism per se but the educational level of parents helps us understand the degree to which groups of students are predisposed to actively respond to such situations."

Girls whose parents had completed post-compulsory secondary education or university studies tended to respond to sexist scenarios by confronting the relevant person, whereas in boys with a similar family background, the response was often avoidance.

The study also reveals that, in some cases, the students themselves are not aware of having personally witnessed or experienced this kind of discrimination. "Girls are often exposed to academic sexism that questions their technological competence but they perceive this as being based on their own personal lack of ability and rule out pursuing it as a result," explained Sáinz, adding that, "They don't realize that this is a stereotypical belief applied to women based solely on the fact that they are women." The opposite is true for boys: their decisions and behaviours are also strongly conditioned by social and cultural expectations related to masculinity.

To prevent these kinds of imbalances, the expert stressed the importance of educating boys and girls on issues related to equality and how to deal with different academic or other types of sexist scenario; a programme that would also need to be extended to teachers and families.

People in what is now Washington State were smoking Rhus glabra, a plant commonly known as smooth sumac, more than 1,400 years ago.

The discovery, made by a team of Washington State University researchers, marks the first-time scientists have identified residue from a non-tobacco plant in an archeological pipe.

Unearthed in central Washington, the Native American pipe also contained residue from N. quadrivalvis, a species of tobacco not currently grown in the region but that is thought to have been widely cultivated in the past. Until now, the use of specific smoking plant mixtures by ancient people in the American Northwest had only been speculated about.

"Smoking often played a religious or ceremonial role for Native American tribes and our research shows these specific plants were important to these communities in the past," said Korey Brownstein, a former WSU Ph.D. student now at the University of Chicago and lead author of a study on the research in the journal Frontiers in Molecular Biosciences. "We think the Rhus glabra may have been mixed with tobacco for its medicinal qualities and to improve the flavor of smoke."

The discovery was made possible by a new metabolomics-based analysis method that can detect thousands of plant compounds or metabolites in residue collected from pipes, bowls and other archeological artifacts. The compounds can then be used to identify which plants were smoked or consumed.

"Not only does it tell you, yes, you found the plant you're interested in, but it also can tell you what else was being smoked," said David Gang, a professor in WSU's Institute of Biological Chemistry and a co-author of the study. "It wouldn't be hyperbole to say that this technology represents a new frontier in archaeo-chemistry."

Previously, the identification of ancient plant residues relied on the detection of a limited number of biomarkers, such as nicotine, anabasine, cotinine and caffeine. Gang said the issue with this approach is while the presence of a biomarker like nicotine shows tobacco was smoked it doesn't distinguish which species it was.

"Also, if you are only looking for a few specific biomarkers, you aren't going to be able to tell what else was consumed in the artifact," Gang said.

In addition to identifying the first non-tobacco plant smoked in an archaeological pipe, the WSU researchers' work also helps elucidate the complex evolution of tobacco trade in the American Northwest.

Analysis of a second pipe that was used by people living in Central Washington after Euro-American contact revealed the presence of a different tobacco species, N. rustica, which was grown by native peoples on the east coast of what is now the United States.

"Our findings show Native American communities interacted widely with one another within and between ecological regions, including the trade of tobacco seeds and materials," said Shannon Tushingham, an assistant professor of anthropology at WSU and co-author of the study. "The research also casts doubt on the commonly held view that trade tobacco grown by Europeans overtook the use of natively-grown smoke plants after Euro-American contact."

Moving forward, the WSU researchers' work could ultimately help scientists studying ancient societies in the Americas and elsewhere around the globe identify which plant species ancient people were consuming, providing important information about the evolution of drug use and similar plant-human dynamics.

Closer to home, the WSU team is also putting their work to use helping confirm connections between ancient plant management practices from before the arrival of Western settlers with cultural traditions of modern indigenous communities such as the Nez Perce.. The researchers shared their work with members of the tribe who also used some of the seeds from the study to grow some of the pre-contact tobacco. The smoking of tobacco is a sacred tradition for Native American groups including the Nez Perce, Colville and other northwest Tribes and before now it was impossible to tell which kind of tobacco their ancestors smoked.

"We took over an entire greenhouse to grow these plants and collected millions of seeds so that the Nez Perce people could reintroduce these native plants back onto their land," Brownstein said. "I think these kinds of projects are so important because they help build trust between us and tribal communities and show that we can work together to make discoveries."

DURHAM, N.C. -- The thin, slippery layer of cartilage between the bones in the knee is magical stuff: strong enough to withstand a person's weight, but soft and supple enough to cushion the joint against impact, over decades of repeat use. That combination of soft-yet-strong has been hard to reproduce in the lab. But now, Duke University researchers say they've created an experimental gel that's the first to match the strength and durability of the real thing.

The material may look like a distant cousin of Jell-O -- which it is -- but it's incredibly strong. It's 60% water, but a single quarter-sized disc can bear the weight of a 100-pound kettlebell without tearing or losing its shape.

Its developers say it's the first hydrogel -- materials made of water-absorbing polymers -- capable of withstanding tugging and heavy loads as well as human cartilage, without wearing out over time.

Led by Duke chemistry and materials scientists Ben Wiley and Ken Gall, the research could one day offer people with knee troubles a replacement for damaged cartilage, and an alternative to the 600,000 knee replacement surgeries performed in the U.S. each year.

A smooth rubbery tissue that covers the ends of bones and enables them to glide smoothly against each other, cartilage helps absorb a huge amount of force with every step -- typically between two and three times your body weight.

However, cartilage also has limited ability to heal and repair itself. Once worn by age, overuse or trauma it's difficult to treat, said Gall, a professor of mechanical engineering and materials science at Duke.

For patients who want to avoid or postpone a knee replacement that may only last 20 years, artificial cartilage can help. Hydrogels have been explored for use as a cartilage substitute since the 1970s and are used in soft contact lenses and disposable diapers. Researchers are attracted to these materials because of their slippery, shock-absorbing properties and because they don't harm nearby cells. But until now they've proven too weak to be used in load-bearing joints like the knee.

The Duke team set out to change that. "We set out to make the first hydrogel that has the mechanical properties of cartilage," said Wiley, a chemistry professor at Duke.

The new hydrogel consists of two intertwined polymer networks: one made of stretchy spaghetti-like strands and the other more rigid and basketlike, with negative charges along their length. These are reinforced with a third ingredient, a meshwork of cellulose fibers.

When the gel is stretched, the cellulose fibers resist pulling and help hold the material together. And when it is squeezed, the negative charges along the rigid polymer chains repel each other and stick to water, helping it spring back to its original shape.

"Only this combination of all three components is both flexible and stiff and therefore strong," said co-author Feichen Yang, who earned a chemistry PhD in Wiley's lab.

When the researchers compared the resulting material to other hydrogels, theirs was the only one that was as strong as cartilage under both squishing and stretching.

In one experiment, the team subjected it to 100,000 cycles of repeat pulling, and the material held up just as well as porous titanium used for bone implants, "which exceeded our initial expectations," said co-author William Koshut, a PhD student in the Gall lab.

They also rubbed the new material against natural cartilage a million times. They found that its smooth, slippery self-lubricating surface is as wear-resistant as the real thing and four times more wear-resistant than synthetic cartilage implants currently FDA-approved for use in the big toe.

Moving the material from the lab to the clinic would take another three years at least, Wiley said. Initial safety tests suggest the material is nontoxic to lab-grown cells. The next step is to design an implant that they can test in sheep.

But the team says eventually the research could offer new options for people with knee pain, and get them back to doing the things they love without the long recovery times and limited lifetime associated with cartilage repair or knee replacement surgery.

The study, published recently in Circulation Research and led by a team from King's College London, has investigated how nitrogen dioxide can impact the cardiovascular system.

The study examined the blood chemistry and cardiovascular changes of 12 healthy volunteers. They sat next to a domestic gas cooker for ninety minutes followed by ninety minutes with normal background nitrogen levels. On another occasion, the volunteers were exposed to normal background nitrogen dioxide levels for three hours.

The period next to a gas cooker increased nitrogen dioxide levels in the air 10-fold and subsequently lowered blood pressure by 5 mm Hg from 45 minutes onwards. The study also found that blood levels of the substance nitrite increased by 15% after 15 minutes.

Previous studies have shown nitrite, which can be converted from dietary nitrate following the ingestion of green leafy vegetables and beetroot, can lower blood pressure. This study suggests nitrite can also be made when the body processes nitrogen dioxide and makes a link between previous research focusing on dietary nitrate and studies of inhalation of nitrogen dioxide for the first time.

Air pollution contributes to illness and death in the general population, but it is a complex mixture of airborne particles and gases, including nitrogen dioxide. Working out the individual effects of each is challenging and there has been a running debate about how to distinguish between the independent effects of nitrogen dioxide and respirable particles in the air.

While the evidence linking nitrogen dioxide to a worsening of symptoms in respiratory disease is well established, its short-term impact on the heart and circulation is less clear. Notably, people with domestic gas appliances or people working in kitchens with gas cookers may be exposed to higher levels of nitrogen dioxide, but with less particulate matter, than that found on the street.

This unique study helps to shed light on some of the rapid effects of nitrogen dioxide on the heart and circulation. Looking at previous air pollution studies, it had been unclear whether the nitrite in the blood came from nitrogen dioxide or from particulate matter causing inflammation and generation of nitric oxide, which is converted to nitrite. This study suggests that it is the nitrogen dioxide that causes nitrite to be formed in the blood.

Crucially, while this effect of short-term exposure to nitrogen dioxide in healthy volunteers may be beneficial, there are other studies of adverse effects of long-term exposure to nitrogen dioxide, and on adverse effects of short-term exposure in asthmatics.

Further research will confirm these findings in larger studies and examine the effects on a more varied cohort.

Dr Andrew Webb, Clinical Senior Lecturer at King's College London, said: "High blood pressure is the biggest single contributor to deaths around the world. Therefore, if exposure to nitrogen dioxide from gas cookers contributes to lowering blood pressure, this could be beneficial per se, and in the context of general air pollution may partially offset the adverse cardiovascular effects of short-term exposures to elevated particulate matter concentrations.

"The mechanism by which nitrogen dioxide lowers blood pressure appears to be through linking into the same pathway as dietary nitrate (found in green leafy vegetables and beetroot): both result in an increase in blood nitrite levels. Therefore, it is not just what you eat, but how you cook it that matters."