Culture

A new study suggests that adults experienced few changes in "Big Five" personality traits as a result of the initial phase of the COVID-19 pandemic in the U.S. Angelina Sutin of Florida State University College of Medicine and colleagues present these findings in the open-access journal PLOS ONE on August 6, 2020.

The "Big Five" personality traits-- extraversion, neuroticism, openness to experience, agreeableness, and conscientiousness--are part of a psychological framework known as the Five Factor Model. These traits typically remain stable in normal circumstances, but they can change in response to unusual distress.

Sutin and colleagues hypothesized that the coronavirus pandemic and efforts to control it could be disruptive enough to change personality traits. To test this idea, they surveyed 2,137 adults from across the U.S. in early February 2020, before the pandemic had reached critical levels in the U.S., and again in mid March, when its impact had become widespread.

Analysis of the survey responses showed few changes in the five personality traits over the study period, suggesting that people's personalities remained relatively stable.

However, while the researchers hypothesized that people's neuroticism would increase, it instead decreased slightly. This could be because participants attributed any increased anxiety and distress (components of neuroticism) to external factors, rather than their own personalities.

In addition, the researchers expected to see increased conscientiousness due to messages promoting actions to slow disease spread. However, conscientiousness did not change. This could be because the pandemic provided a new social context for a specific question about going to work despite feeling sick, which may have previously seemed like a dutiful action, but could now be seen as irresponsible.

Further work will be needed to confirm the small changes seen in this study and determine whether they are long-lasting. Additional research could also reveal whether the pandemic is causing personality changes that are taking longer to appear.

The authors add: "The coronavirus pandemic has disrupted most aspects of our lives, from health to social relationships to economic security. Yet, this disruption had little effect on personality traits, which shows the resiliency of personality even to catastrophic events, at least in the short-term."

When we dream, our brains are filled with noisy electrical activity that looks nearly identical to that of the awake brain.

But University of California, Berkeley, researchers have pulled a signal out of the noise that uniquely defines dreaming, or REM sleep, potentially making it easier to monitor people with sleep disorders, as well as unconscious coma patients or those under anesthesia.

Each year, hundreds of thousands of people undergo overnight studies to diagnose problems with their sleep, most of them hooked up to an electroencephalogram (EEG) to monitor brain activity as they progress from wakefulness to deep, slow-wave sleep and on into REM sleep. But EEGs alone can not tell whether a patient is awake or dreaming: Doctors can only distinguish REM sleep by recording rapid eye movement -- hence, the name -- and muscle tone, since our bodies relax in a general paralysis to prevent us from acting out our dreams.

"We really now have a metric that precisely tells you when you are in REM sleep. It is a universal metric of being unconscious," said Robert Knight, UC Berkeley professor of psychology and neuroscience and senior author of a paper describing the research that was published July 28 in the online journal eLife.

"These new findings show that, buried in the electrical static of the human brain, there is something utterly unique -- a simple signature," said co-author and sleep researcher Matthew Walker, UC Berkeley professor of psychology and neuroscience. "And if we measure that simple electrical signature, for the first time, we can precisely determine exactly what state of consciousness someone is experiencing -- dreaming, wide awake, anesthetized or in deep sleep."

The ability to distinguish REM sleep by means of an EEG will allow doctors to monitor people under anesthesia during surgery to explore how narcotic-induced unconsciousness differs from normal sleep -- a still-unsettled question. That's the main reason first author Janna Lendner, a medical resident in anesthesiology, initiated the study.

"We often tell our patients that, 'You will go to sleep now,' and I was curious how much these two states actually overlap," said Lendner, a UC Berkeley postdoctoral fellow in her fourth year of residency in anesthesiology at the University Medical Center in Tübingen, Germany. "Anesthesia can have some side effects. If we learn a little bit about how they overlap -- maybe anesthesia hijacks some sleep pathways -- we might be able to improve anesthesia in the long run."

Sleep soothes the brain

Sleep, as Walker wrote in his 2017 book, "Why we Sleep," "enriches a diversity of functions, including our ability to learn, memorize, and make logical decisions and choices. Benevolently servicing our psychological health, sleep recalibrates our emotional brain circuits, allowing us to navigate next-day social and psychological challenges with cool-headed composure."

Disrupted sleep interferes with all of this, increasing the risk of medical, psychiatric and neurological diseases.

Most sleep research focuses on the synchronized, rhythmic waves that flow through the neural network of the brain, from the slow waves that signal deep sleep, typically in the first few hours of the night, to the higher frequency waves typical of dream sleep. These waves pop out above a lot of general activity, also called the 1/f, that has typically been dismissed as noise and ignored.

But Knight and his lab have been looking at this "noise" for a decade and found that it contains useful information about the state of the brain. In 2015, for example, he and Bradley Voytek, a former doctoral student now on the faculty at UC San Diego, discovered that the amount of high frequency activity increases with age. Lendner has now found that a faster drop-off of high-frequency activity, relative to low-frequency activity, is a unique signature of REM sleep.

"There is this background activity, which is not rhythmic, and we have overlooked that for quite a long time," Lendner said. "Sometimes, it has been called noise, but it is not noise; it carries a lot of information, also about the underlying arousal level. This measure makes it possible to distinguish REM sleep from wakefulness by looking only at the EEG."

Since slow waves are associated with inhibition of activity in the brain, while high frequency activity -- like that found during wakefulness -- is associated with excitatory behavior, the sharper drop-off may be an indication that many activities in the brain, including those related to muscle movement, are being tamped down during REM sleep.

The new measure quantifies the relationship of brain activity at different frequencies -- how much activity there is at frequencies from about 1 cycle per second to 50 cycles per second -- and determines the slope, that is, how fast the spectrum drops. This 1/f "drop-off" is sharper in REM sleep than in wakefulness or when under anesthesia.

Lendner found this characteristic measure in the nighttime brain activity of 20 people recorded via EEG scalp electrodes in Walker's UC Berkeley sleep lab and in 10 people who had electrodes placed in their brains to search for the causes of epilepsy as a necessary prologue to brain surgery to alleviate seizures.

She also recorded brain activity in 12 epilepsy patients and 9 other patients undergoing spinal surgery with the common general anesthetic Propofol.

Lendner is now reviewing brain recordings from coma patients to see how their brain activity varies over the course of a day and whether the 1/f drop-off can be used to indicate the likelihood of emergence from coma.

"More importantly, I think it is another metric for evaluating states of coma," Knight said. "1/f is very sensitive. It could resolve, for instance, if someone was in a minimally conscious state, and they are not moving, and whether they are more alert than you think they are."

Are we medically intervening in maternity care when we don't need to?

Researchers from the School of Nursing and Midwifery at Trinity College Dublin have provided an international perspective on differences in key birth interventions as part of a European research network on understanding and contextualising physiological labour and birth (EU COST Action IS1405), which provides insights into maternity care practices and costs in Ireland.

The School's two studies are published in a special maternity care themed edition of the online journal PLOS ONE (Thursday, 6th August 2020).

The first study - Economic implications of reducing caesarean section rates - analysis of two health systems - looks at the cost implications of reducing caesarean sections rates (CS rates) among first-time mothers, along with improving rates of vaginal births after c-sections.

Caesarean section (CS) rates throughout Europe have risen significantly over the last two decades. As well as being an important clinical issue, these changes in mode of birth may have substantial resource implications. Policy initiatives to curb this rise have had to contend with the multiplier effect of women who had a CS for their first birth having a greater likelihood of requiring one during subsequent births, thus making it difficult to decrease CS rates in the short term.

The study examined the long-term resource implications of reducing CS rates among first-time mothers, as well as improving rates of vaginal birth after caesarean section (VBAC), among an annual cohort of women over the course of their most active childbearing years (18 to 44 years) in two public health systems in Europe; Ireland and England/Wales.

Researchers found that the economic benefit of improvements in these two outcomes is considerable, with the net present value of the savings associated with a five-percentage-point change in nulliparous (a woman who has yet to give birth to a child) CS rates and VBAC rates being €1.1million and £9.8million per annual cohort of 18-year-olds in Ireland and England/Wales, respectively.

Reductions in CS rates among first-time mothers are associated with a greater payoff than comparable increases in VBAC rates. The net present value of achieving CS rates comparable to those currently observed in the best performing Scandinavian countries was €3.5M and £23.0M per annual cohort in Ireland and England/Wales, respectively.

Dr Patrick Moran, Adjunct Assistant Professor of Health Economics at the School of Nursing and Midwifery said:

"Our results show that in addition to the reported clinical benefits, there is a significant economic benefit of reducing caesarean section rates among those for whom it is safe to do so in Ireland. This can free up vital maternity care resources to strengthen maternity services in Ireland and improve outcome for women, children and families."

READ: You can read the paper Economic implications of reducing caesarean section rates - analysis of two health systems here: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0228309

The second study from the School of Nursing and Midwifery - How much synthetic oxytocin is infused during labour? A review and analysis of regimens used in 12 countries - highlights the national and institution regimens on the use of oxytoxin, the most common drug used to induce labour, across 11 European countries and South Africa.

This study examined the use of oxytocin to induce labour. Oxytocin is widely used, but even 70 years after it was first introduced in clinical practice, there is still no agreement on the optimal infusion regimen to use during induction (starting) or augmentation (speeding up) in labour.

The study found that across the 16 regimens, there were considerable variations which were noted, with an 11-fold difference between minimum and maximum amounts. As oxytocin is a potentially harmful medication, with serious consequences for mum and baby, it is vital that the appropriate minimum infusion rate is administered.

Ireland is one of only five countries in the study with a national oxytocin infusion regimen; with one Irish hospital using a different regimen. All other countries use differing amounts of oxytocin.

The study found that the total amount of IU (international unit) oxytocin infused, estimated over eight hours, ranged from 2.38 IU to 27.00 IU, a variation of 24.62 IU and an 11-fold difference over the 16 regimens. In Ireland, the total amount infused in one regimen was 4.08 IU, just slightly above the lowest of the 16 regimens, and 13.05 IU in the other hospital regimen, which was the second highest amount but very close to several other regimens.

Dr Deirdre Daly, Assistant Professor in Midwifery at the School of Nursing and Midwifery said:

"In the era of evidence-based health care, the fact that such widespread variation exists in the use of infused oxytocin, and in the total amount infused, reflects potential overuse in many settings. All maternity care professionals are driven by the need to reduce avoidable maternal and neonatal morbidity and mortality, but it is crucial that intrapartum interventions designed to reduce risk for some who have complications are not used routinely for others who are healthy.''

READ: You can read the paper How much synthetic oxytocin is infused during labour? A review and analysis of regimens used in 12 countries, here: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0227941

There's a reason why blue fruits are so rare: the pigment compounds that make fruits blue are relatively uncommon in nature. But the metallic blue fruits of Viburnum tinus, a popular landscaping plant in Europe, get their color a different way. Instead of relying solely on pigments, the fruits use structural color to reflect blue light, something that's rarely seen in plants. Researchers reporting August 6 in the journal Current Biology show that the fruits use nanostructures made of lipids in their cell walls, a previously unknown mechanism of structural color, to get their striking blue--which may also double as a signal to birds that the fruits are full of nutritious fats.

"Structural color is very common in animals, especially birds, beetles, and butterflies, but only a handful of plant species have ever been found to have structural color in their fruits," says co-first author Miranda Sinnott-Armstrong, a postdoctoral researcher at the University of Colorado-Boulder. "This means that V. tinus, in addition to showing a completely novel mechanism of structural color, is also one of the few known structurally colored fruits."

Senior author Silvia Vignolini (@VignoliniLab), a physical chemist at the University of Cambridge, has been interested in the plants for nearly 10 years. "I actually found this Viburnum in a garden in Italy and observed that they looked weird, so we measured them at the time but didn't have conclusive results. It was kind of always on the back of my mind," she says. As her team grew, they become more interested in V. tinus and eventually had the capability to examine the structure of the fruits using electron microscopy. "Before we got the images, we were just seeing all these blobs," she says. "When we found out that those blobs were lipids, we got very excited."

While most plants have cell walls made of cellulose, used to make cotton and paper, V. tinus fruit cells have much thicker walls with thousands of globular lipids arranged in layers that reflect blue light. The structure formed by this so-called lipid multilayer allows the fruits to create their vibrant blue color while containing no blue pigment. "This is very strange because globular lipids like these are not usually found in this arrangement in the cell wall, as they are normally stored inside the cell and used for transport," says co-first author Rox Middleton, a physicist who studied the optical response of the fruits during her PhD and is now a postdoctoral researcher at the University of Bristol. "We also believe that this lipid may contribute to the fruit's nutrition. That means that the fruit can demonstrate how nutritious it is by being a beautiful, shiny blue."

This extra nutrition would be important for V. tinus's main consumers: birds that disperse the plant's seeds. Although the researchers can't say for sure whether the lipids are used as fat by the birds that consume them, there is reason to believe they might be. If so, the researchers suggest that the metallic blue color made by the lipid multilayer could indicate to the birds that if they see this striking blue, the fruit in question will have enough nutrients to make it a worthwhile meal. "While birds have been shown to be attracted to blue fruits," says Vignolini, "other blue fruits that we have studied essentially don't have any nutritional value."

Going forward, the researchers want to see how widespread blue structural color is in fruits to understand its ecological significance. They had never seen this type of lipid multilayer in a biomaterial before, but since their discovery, they've begun to take notice of other species. "We actually realize now that there are some older electron microscopy pictures from other plants where you can see the blobs. The researchers didn't know that they were lipids at the time, or that lipids could even form this type of structure, but our research suggests that they very well could be, meaning this structure may not be limited to Viburnum," Vignolini says.

Additionally, learning how V. tinus can use such a unique mechanism to make color may have implications for how we color our own foods. "There are lots of problems connected to food coloration," says Vignolini. She adds that once this mechanism is better understood, it could potentially be used to create a healthier, more sustainable food colorant.

But right now, Vignolini is just excited her initial hunch paid off: "I've been working on this type of photonic structure for quite a while, and I was beginning to think there were no new ways to make it--at some point you've seen so many that you think, 'This is more or less the end, it's going to be difficult to find something new,'" she says. "Instead, we discovered much more than what we expected."

Much smaller than its counterpart, the X chromosome, the Y chromosome has shrunken drastically over 200 million years of evolution. Even those who study it have used the word "wimpy" to describe it, and yet it continues to stick around even though sex chromosomes in non-mammalian vertebrates are known to experience quite a bit of evolutionarily turnover. An Opinion paper publishing on August 6 in the journal Trends in Genetics outlines a new theory--called the "persistent Y hypothesis"--to explain why the Y chromosome may be more resilient than it first appears.

"The Y chromosome is generally thought to be protected from extinction by having important functions in sex determination and sperm production, which, if moved to somewhere else in the genome, would signal its demise," says co-author Paul Waters, a professor at the University of New South Wales in Sidney, Australia. "However, we propose that the future of the Y chromosome is secure because it carries executioner genes that are critical for successful progression of male meiosis--and unlike other genes on the Y, these executioners self-regulate."

During meiosis, sexually reproducing organisms form haploid gametes (eggs and sperm), each of which contains only one copy of each chromosome. They do this through one round of genome replication followed by two consecutive rounds of cell division. This meiotic process is tightly regulated to avoid infertility and chromosome abnormalities.

One step of meiosis requires the silencing of both the X and Y chromosomes during a specific window. "Importantly, the Y chromosome bears genes that regulate this process, a feature that has been known for years now," says co-author Aurora Ruiz-Herrera, a professor at Universitat Autònoma de Barcelona in Spain. "We believe that bearing these genes is what protects the Y chromosome from extinction. The genes that regulate the silencing process, the Zfy genes, are called 'executioner' genes. When these genes are turned on at the wrong time and at the wrong place during meiosis, they are toxic and execute the developing sperm cell. They essentially act as their own judge, jury, and executioner, and in doing so, protect the Y from being lost."

The Y chromosome is present in all but a handful of mammalian species. Important contributions to understanding the Y chromosome have come from looking at the rare mammals that don't follow the rules--for example, a handful of species of rodents. "I've always been a firm believer that the comparison of unusual systems is informative to other systems," Waters says. "Determining the common prerequisites for rare Y chromosome loss enabled us to build a hypothesis for how Y chromosomes persist in most species."

The collaboration between Waters and Ruiz-Herrera--based half a world apart--began to bear fruit during the COVID-19 pandemic. "Earlier this year, we put together a grant application to examine aspects of X chromosome silencing during meiosis," says Waters. "After the shutdown of our labs, we decided to massage our discussions into a review article. We had no idea we would essentially stumble onto such an intuitive mechanism to explain why the mammal Y chromosome has persisted in most species." Going forward, the researchers plan to take a closer look at how the executioner genes evolved and to look at how they are regulated from evolutionary and functional perspectives.

"The mammalian Y has been taken as a symbol of masculinity, not only in popular culture but also in the scientific community," Ruiz-Herrera says. "Despite that, many have projected that, given enough time, it will be eventually lost. However, we propose the Y chromosome can escape this fatal fate. So our male colleagues can breathe easy: the Y will persist!"

Researchers have found that a common plant owes the dazzling blue colour of its fruit to fat in its cellular structure, the first time this type of colour production has been observed in nature.

The plant, Viburnum tinus, is an evergreen shrub widespread across the UK and the rest of Europe, which produces metallic blue fruits that are rich in fat. The combination of bright blue colour and high nutritional content make these fruits an irresistible treat for birds, likely increasing the spread of their seeds and contributing to the plant's success.

The researchers, led by the University of Cambridge, used electron microscopy to study the structure of these blue fruits. While there are other types of structural colour in nature - such as in peacock feathers and butterfly wings - this is the first time that such a structure has been found to incorporate fats, or lipids. The results are reported in the journal Current Biology.

"Viburnum tinus plants can be found in gardens and along the streets all over the UK and throughout much of Europe -- most of us have seen them, even if we don't realise how unusual the colour of the fruits is," said co-first author Rox Middleton, who completed the research as part of her PhD at Cambridge's Department of Chemistry.

Most colours in nature are due to pigments. However, some of the brightest and most colourful materials in nature - such as peacock feathers, butterfly wings and opals - get their colour not from pigments, but from their internal structure alone, a phenomenon known as structural colour. Depending on how these structures are arranged and how ordered they are, they can reflect certain colours, creating colour by the interaction between light and matter.

"I first noticed these bright blue fruits when I was visiting family in Florence," said Dr Silvia Vignolini from Cambridge's Department of Chemistry, who led the research. "I thought the colour was really interesting, but it was unclear what was causing it."

"The metallic sheen of the Viburnum fruits is highly unusual, so we used electron microscopy to study the structure of the cell wall," said co-first author Miranda Sinnott-Armstrong from Yale University. "We found a structure unlike anything we'd ever seen before: layer after layer of small lipid droplets."

The lipid structures are incorporated into the cell wall of the outer skin, or epicarp, of the fruits. In addition, a layer of dark red anthocyanin pigments lies underneath the complex structure, and any light that is not reflected by the lipid structure is absorbed by the dark red pigment beneath. This prevents any backscattering of light, making the fruits appear even more blue.

The researchers also used computer simulations to show that this type of structure can produce exactly the type of blue colour seen in the fruit of Viburnum. Structural colour is common in certain animals, especially birds, beetles, and butterflies, but only a handful of plant species have been found to have structurally coloured fruits.

While most fruits have low fat content, some - such as avocadoes, coconuts and olives - do contain lipids, providing an important, energy-dense food source for animals. This is not a direct benefit to the plant, but it can increase seed dispersal by attracting birds.

The colour of the Viburnum tinus fruits may also serve as a signal of its nutritional content: a bird could look at a fruit and know whether it is rich in fat or in carbohydrates based on whether or not it is blue. In other words, the blue colour may serve as an 'honest signal' because the lipids produce both the signal (the colour) and the reward (the nutrition).

"Honest signals are rare in fruits as far as we know," said Sinnott-Armstrong. "If the structural colour of Viburnum tinus fruits are in fact honest signals, it would be a really neat example where colour and nutrition come at least in part from the same source: lipids embedded in the cell wall. We've never seen anything like that before, and it will be interesting to see whether other structurally coloured fruits have similar nanostructures and similar nutritional content."

One potential application for structural colour is that it removes the need for unusual or damaging chemical pigments - colour can instead be formed out of any material. "It's exciting to see that principle in action - in this case the plant uses a potentially nutritious lipid to make a beautiful blue shimmer. It might inspire engineers to make double-use colours of our own," said Vignolini.

The research was supported in part by the European Research Council, the EPSRC, the BBSRC and the NSF.

Inside every cell lies a genome - a full set of DNA that contains the instructions for building an organism. Across the biological world, genomes show a staggering diversity in size. For example, the genome of the Japanese white flower, Paris japonica, is over 150 billion base pairs, meaning that almost 100 meters of DNA is squeezed into each cell. In comparison, single-celled prokaryotes, like bacteria, have tiny genomes, averaging less than 5 million base pairs. Some prokaryotes have even smaller genomes that are fewer than 500,000 base pairs. But scientists still don't fully understand the driving forces responsible for reducing the size of genomes.

Now, in an international collaboration, led by the Okinawa Institute of Science and Technology Graduate University (OIST) and the University of Sydney, and including researchers from the University of the Ryukyus, the Tokyo Institute of Technology, and RIKEN, scientists have found a link between mutation rate - how quickly the DNA sequence changes - and genome size. Writing in Current Biology, the researchers reported that prokaryotes with higher mutation rates lose genes at a faster pace, and therefore have smaller genomes.

"This was a really surprising result," said Professor Tom Bourguignon, co-first author of the study and head of the Evolutionary Genomics Unit at OIST. "Currently, the most accepted idea is that population size is the main factor that determines genome size in prokaryotes, particularly in endosymbionts, but our research challenges this view."

Endosymbionts are organisms that live inside the bodies or cells of other organisms, and typically have much smaller genomes than their free-living counterparts. The Evolutionary Genomics Unit researches an endosymbiont called Blattabacterium, a bacterial species that lives inside cockroaches and termites and provides their hosts with vital nitrogen-containing nutrients. But only a small number of these bacteria are passed on from a mother insect host to a daughter insect host, which keeps their effective population size very low.

"At small population sizes, natural selection is much less effective, and evolution is driven more strongly by chance," said Dr. Yukihiro Kinjo, co-first author and a postdoctoral scholar from the Evolutionary Genomics Unit. "Without enough selection pressure to maintain specific genes, mutations can arise that inactive and erode these genes, eventually leading to their total loss from the genome."

While population size as a driving force for genome reduction may be an attractive idea, many free-living prokaryotes that live in larger populations have also evolved smaller genomes, suggesting that it's only part of the story. Additional explanations have also been proposed but, until now, the mutation rate - or the speed at which evolution occurs - has been overlooked.

In the study, the scientists collected genome data from a diverse range of prokaryotes, including strains from two endosymbiotic lineages and seven free-living lineages.

For each lineage, the team constructed an evolutionary tree that showed how the strains had diverged from each other. With the help of the OIST Biological Complexity Unit, led by Professor Simone Pigolotti, the scientists then created models that reconstructed how gene loss had occurred in each strain. They then estimated the mutation rate, population size and selection pressure for each strain and compared it to the amount of gene loss.

Surprisingly, the scientists did not find a clear link between estimated population size and rate of gene loss. Instead, they found a relationship between mutation rate and gene loss for seven out of the nine lineages studied, with higher mutation rates associated with faster rates of gene loss, resulting in smaller genomes.

"Although we haven't established a cause, there is a theoretical prediction that explains this observation; if the rate of mutation outweighs a selection pressure to maintain a gene, the gene will be lost from the genome," said Dr. Kinjo.

The scientists also found clues as to how the gene loss occurred, as strains with smaller genomes had lost genes involved in repairing DNA.

"DNA repair genes fix damaged DNA, so when they are lost the mutation rate of a strain can quickly increase. Most mutations are harmful, so this can quickly inactivate other genes and drive their loss from the genome. If some of these inactivated genes are also involved in DNA repair, this can further accelerate mutation rate and gene loss," explained Professor Gaku Tokuda, from the University of the Ryukyus.

Although the answers to how gene loss occurs are becoming clearer, whether there are evolutionary reasons behind why prokaryotes increase their rate of mutation to shrink their genome, and if so, what these reasons are, remains an open question.

"Figuring out the evolutionary explanation for what we see is really complicated. It could be that an increased rate of mutation occurs to provide an adaptive advantage, such as the removal of unwanted or unnecessary genes. But we still can't rule out the possibility that the increased rate of mutation is non-adaptive and due to chance," said Dr. Kinjo.

Overall, their findings shed new light on the evolution of small genomes, prompting a re-think of the current dominant idea of genome reduction being driven by small population sizes.

"Unlike with population size, our results suggest that mutation rate could drive genome reduction in both free-living and endosymbiotic prokaryotes. This could be the first step in comprehensively understanding what drives changes in genome size across all prokaryotes," said Prof. Bourguignon.

A fossil called Tanystropheus was first described in 1852, and it's been puzzling scientists ever since. At one point, paleontologists thought it was a flying pterosaur, like a pterodactyl, and that its long, hollow bones were phalanges in the finger that supported the wing. Later on, they figured out that those were elongated neck bones, and that it was a twenty-foot-long reptile with a ten-foot neck: three times as long as its torso. Scientists still weren't sure if it lived on land or in the water, and they didn't know if smaller specimens were juveniles or a completely different species--until now. By CT-scanning the fossils' crushed skulls and digitally reassembling them, researchers found evidence that the animals were water-dwelling, and by examining the growth rings in bones, determined that the big and little Tanystropheus were separate species that could live alongside each other without competing because they hunted different prey.

"I've been studying Tanystropheus for over thirty years, so it's extremely satisfying to see these creatures demystified," says Olivier Rieppel, a paleontologist at the Field Museum in Chicago and one of the authors of a new paper in Current Biology detailing the discovery.

Tanystropheus lived 242 million years ago, during the middle Triassic. On land, dinosaurs were just starting to emerge, and the sea was ruled by giant reptiles. For a long time, though, scientists weren't sure whether Tanystropheus lived on land or in the water. Its bizarre body didn't make things clear one way or the other.

"Tanystropheus looked like a stubby crocodile with a very, very long neck," says Rieppel. The larger specimens were twenty feet long, with their necks making up ten feet of that length. Oddly for animals with such long necks, they only had thirteen neck vertebrae, just really elongated. (We see the same thing with giraffes, which have only seven neck bones, just like humans.) And their necks were rather inflexible, reinforced with extra bones called cervical ribs.

In the same region where many of the big Tanystropheus fossils were found, in what's now Switzerland, there were also fossils from similar-looking animals that were only about four feet long. So not only were scientists unsure if these were land-dwellers or marine animals, but they also didn't know if the smaller specimens were juveniles, or a separate species from the twenty-footers.

To solve these two long-standing mysteries, the researchers used newer technologies to see details of the animals' bones. The large Tanystropheus fossils' skulls had been crushed, but Stephan Spiekman, the paper's lead author and a researcher at the University of Zurich, was able to take CT scans of the fossil slabs and generate 3D images of the bone fragments inside.

"The power of CT scanning allows us to see details that are otherwise impossible to observe in fossils," says Spiekman. "From a strongly crushed skull we have been able to reconstruct an almost complete 3D skull, revealing crucial morphological details."

The skulls had key features, including nostrils on top of the snout like a crocodile's, that suggested Tanystropheus lived in the water. It probably lay in wait, waiting for fish and squid-like animals to swim by, and then snagged them with its long, curved teeth. It may have come to land to lay eggs, but overall, it stayed in the ocean.

Rieppel wasn't surprised that evidence pointed to a water-dwelling Tanystropheus. "That neck doesn't make sense in a terrestrial environment," he says. "It's just an awkward structure to carry around."

So that answered one question, about where Tanystropheus lived. To learn whether the small specimens were juveniles or a separate species, the researchers examined the bones for signs of growth and aging.

"We looked at cross sections of bones from the small type and were very excited to find many growth rings. This tells us that these animals were mature," says Torsten Scheyer, the study's senior author and a researcher at University of Zurich.

"The small form is an adult, which basically sealed the case," says Rieppel. "It's proven now that these are two species." The researchers named the larger one Tanystropheus hydroides, after the long-necked hydras in Greek mythology. The small form bears the original name Tanystropheus longobardicus.

"For many years now we have had our suspicions that there were two species of Tanystropheus, but until we were able to CT scan the larger specimens we had no definitive evidence. Now we do," says Nick Fraser, Keeper of Natural Sciences at National Museums Scotland and a co-author of the paper. "It is hugely significant to discover that there were two quite separate species of this bizarrely long-necked reptile who swam and lived alongside each other in the coastal waters of the great sea of Tethys approximately 240 million years ago."

The animals' different sizes, along with cone-shaped teeth in the big species and crown-shaped teeth in the little species, meant they probably weren't competing for the same prey.

"These two closely related species had evolved to use different food sources in the same environment," says Spiekman. "The small species likely fed on small shelled animals, like shrimp, in contrast to the fish and squid the large species ate. This is really remarkable, because we expected the bizarre neck of Tanystropheus to be specialized for a single task, like the neck of a giraffe. But actually, it allowed for several lifestyles. This completely changes the way we look at this animal."

This "splitting up" of a habitat to accommodate two similar species is called niche partitioning. "Darwin focused a lot on competition between species, and how competing over resources can even result in one of the species going extinct," says Rieppel. "But this kind of radical competition happens in restricted environments like islands. The marine basins that Tanystropheus lived in could apparently support niche partitioning. It's an important ecological phenomenon."

"Tanystropheus is an iconic fossil and has always been," adds Rieppel. "To clarify its taxonomy is an important first step to understanding that group and its evolution."

A new analysis of sibling records from more than 300,000 individuals suggests that some parents continue to reproduce until they have children of both sexes.

The practice, which the two University of Michigan biologists who conducted the study dubbed "coupon-collection behavior" in human reproduction, appears to have increased in popularity in recent decades and reduces the amount of sex-ratio variation among families.

In a study scheduled for publication Aug. 6 in the journal Current Biology, Jianzhi Zhang and Erping Long report that significantly more families than expected had children of the same sex except for the last-born child. The trend is more pronounced in the most recent data.

"We believe that coupon-collection behavior becomes popular only when daughters and sons are considered to have similar utility to families, which would require society-wide improvement in gender equality and appreciation of gender diversity," said Zhang, a professor in the U-M Department of Ecology and Evolutionary Biology.

The coupon collector's problem comes from probability theory, where it refers to someone who continues to buy a particular brand of cereal, each package of which contains one randomly placed coupon, until he or she collects all the different types of coupons in the set.

Zhang and Long propose that the concept also applies to reproductive behaviors that reflect a preference for having children of both sexes. At the time of this work, Long was a U-M visiting scientist from Sun Yat-sen University in Guangzhou, China.

Their conclusions are based on an analysis of sibling records from the UK Biobank database, which contains genetic, health and family information from volunteer participants in the United Kingdom, the vast majority of whom were born between 1940 and 1970.

The results relating to sex ratio, defined as the proportion of male children in a family, are best explained by 3.3% of the families using coupon-collecting behavior to pursue children of both sexes, according to the researchers. That number is considered a conservative estimate, and the true fraction of families following coupon-collection behavior is likely to be higher.

"Our hypothesis is consistent with reports that Europeans express in interviews their desires to have children of both sexes, and the observations in Denmark, Sweden and Finland that the probability for a mother to have a third child is higher when the first two children are of the same sex than when they are of different sexes," Zhang and Long wrote.

To confirm coupon-collection reproductive behavior and its rising popularity in other populations, the researchers also examined a family tree-based genealogical database that contains 241,000 Dutch families over four centuries, with known numbers and genders of children of each family. They found higher-than-expected sex ratio (SR) variations over much of the history; only after 1940 did sex-ratio variation drop below expected levels.

The Dutch data revealed "a profound difference in the among-family variation of SR after 1940 when compared with the preceding 3.4 centuries," Zhang and Long reported. "Thus, the analysis of the Dutch data confirms the finding from the UK Biobank and suggests that the coupon-collection reproductive behavior is a relatively recent phenomenon."

The odds of conceiving a boy versus a girl are believed to be 50-50, and the outcome is determined by which of the father's sperm makes it to the mother's egg first. If the egg is fertilized by a sperm bearing a Y chromosome, the result is a boy. If it's an X-bearing sperm, a girl.

But post-conception factors can affect the odds of having a boy or a girl, and scientists have known for centuries that slightly more boys are born each year than girls. In the United States, about 51% of the babies born are male.

There is growing evidence for genetic influences on the probability that a birth yields one biological sex over the other. For example, women who carry the BRCA1 and BRCA2 breast cancer susceptibility genes tend to have more female children.

Various environmental factors during pregnancy may also influence the biological sex of the child. And of course, modern contraception, fertility treatments and abortion can all affect the sex ratio in a family.

If the determination of biological sex at birth were a completely random event--like a 50-50 coin toss--then the probability that a birth yields a boy instead of a girl, known to scientists as Pboy, would be 0.5 for every birth in every family.

But increasing evidence suggests a variable Pboy among families, and the amount of variation around the 0.5 hypothetical random event is known in statistics as the standard deviation (SD) around the mean. The original goal of the study by Zhang and Long was to see whether Pboy is variable in a large set of families and, if so, to determine how variable it is.

Because the sex ratio of the children in a family provides an unbiased though imprecise estimate of the family's Pboy, the standard deviation of the sex ratio among families--the SD of SR--can be used to assess among-family variation in Pboy.

"You can imagine that the SD of SR will be higher if Pboy varies among families than when it is always 0.5," Zhang said. "Surprisingly, we found that the SD of SR is smaller than when Pboy is always 0.5. This unexpected observation suggests that some other factors are at work."

Those other factors likely include coupon-collection behavior by a small percentage of the families, according to Zhang and Long. Zhang noted that the decline of the SD of SR does not affect the overall sex ratio in a society.

What The Study Did: SARS-CoV-2 molecular viral shedding in asymptomatic and symptomatic patients who were isolated in a community treatment center in South Korea is quantitatively described in this observational study.

Authors: Eunjung Lee, M.D., of the Soonchunhyang University Seoul Hospital in Seoul, South Korea, 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/jamainternmed.2020.3862)

Editor's Note: The article includes conflict 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.

What The Study Did: This observational study looked at whether race and socioeconomic factors were associated with children enrolled in national clinical trials receiving high-cost proton radiotherapy for treatment of cancer.

Authors: Daphne A. Haas-Kogan, M.D., of the Dana-Farber Cancer Institute in Boston, 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/jamaoncol.2020.2259)

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, conflict of interest and financial disclosures, and funding and support.

Non-white Americans, especially Asian Americans, are at disproportionately higher risk for gastric cancer compared to non-Hispanic white Americans. A new study breaks down this risk according to specific ethnicities and locations within the stomach.

The study published Aug. 6 in Gastroenterology analyzed California Cancer Registry data for the seven largest Asian American populations (Chinese, Japanese, Korean, Filipino, Vietnamese, South Asian and Southeast Asian) as well as for non-Hispanic whites, non-Hispanic blacks and Hispanic populations.

The population-based study revealed that non-white race and ethnic groups had a several-fold higher risk of developing stomach cancer in the main area of the stomach (noncardia gastric cancer) compared to the non-Hispanic white population. This risk was most striking among Korean Americans age 50 and older, who demonstrated a 12-fold to 14.5-fold higher risk compared to non-Hispanic whites. This is the most common location for stomach cancer to develop. However, Asian Americans -- with the exception of Japanese American men -- had a lower risk than non-Hispanic whites of developing gastric cancer in the upper portion of the stomach where it joins the esophagus (cardia gastric cancer).

"We specifically chose to analyze individuals age 50 years and older since this is the age group for whom average-risk colorectal cancer screening and high-risk esophageal cancer screening is recommended," said Shailja Shah, MD, MPH, assistant professor of Medicine, the study's lead author and corresponding author.

"Unfortunately, even though certain ethnic groups have rates of gastric cancer that even exceed colorectal cancer, and even though gastric cancer is more common than esophageal cancer, screening for gastric cancer does not yet occur in the United States among high-risk groups. We are hopeful that the findings of this study will break the inertia surrounding gastric cancer screening"

The research sets the stage for developing targeted risk reduction programs for gastric cancer in the United States. Shah and colleagues recently published two studies demonstrating that gastric cancer screening starting at age 50 old in non-white race and ethnic groups is cost-effective. Shah was also one of the lead members of the American Gastroenterology Association's Technical Review team on gastric intestinal metaplasia (gastric precancer) surveillance for early gastric cancer detection. Shah's research is set on developing a strong foundation of evidence to establish screening guidelines for gastric cancer in the United States, where the number of people at risk for the cancer is increasing as the nation's population becomes more diverse.

Worldwide, gastric cancer is the fifth most common cancer and third leading cause of cancer-related death. In the United States, gastric cancer ranks 15th among cancers, but it afflicts population groups disproportionately.

The study in Gastroenterology revealed that for gastric cancer in the main area of the stomach, the incidence rate for Korean Americans was 49 cases per 100,000 people, 23.9 for Vietnamese Americans, 21.1 for Southeast Asian Americans (Cambodian, Laotian, Hmong and Thai), 19.2 for Japanese Americans, 17.6 for Chinese Americans, 14.0 for Hispanic Americans, 11.2 for non-Hispanic black Americans, 7.75 for South Asian Americans, 6.69 for Filipino Americans and 3.7 for non-Hispanic white Americans.

Men had significantly higher rates of gastric cancer compared to women. For instance, the rate for gastric cancer in the main area of the stomach was 70.0 per 100,000 for Korean American men compared to 33.5 for Korean American women.

"The immediate need for gastric cancer prevention and early detection efforts in the U.S. is amplified when considering that the pool of at-risk individuals is only expected to grow, with non-Hispanic whites now considered the minority population in 35 of the 50 largest cities and projections that non-Hispanic whites will no longer be the overall majority population by 2065," Shah said.

Its neck was three times as long as its torso, but had only 13 extremely elongated vertebrae: Tanystropheus, a bizarre giraffe-necked reptile which lived 242 million years ago, is a paleontological absurdity. A new study led by the University of Zurich has now shown that the creature lived in water and was surprisingly adaptable.

For over 150 years, paleontologists have puzzled over Tanystropheus, its strangely long neck and whether it lived mostly underwater or on land. An international team led by the University of Zurich has now reconstructed its skull in unprecedented detail using synchrotron radiation micro-computed tomography (SRμCT), an extremely powerful form of CT scanning. In addition to revealing crucial aspects of its lifestyle, this also shows that Tanystropheus had evolved into two different species.

Underwater ambush predator

The researchers were able to reconstruct an almost complete 3D skull from a severely crushed fossil. The reconstruction reveals that the skull of Tanystropheus has several very clear adaptations for life in water. The nostrils are located on the top of the snout, much like in modern crocodilians, and the teeth are long and curved, perfectly adapted for catching slippery prey like fish and squid. However, the lack of visible adaptations for swimming in the limbs and tail also means that Tanystropheus was not a particularly efficient swimmer. "It likely hunted by stealthily approaching its prey in murky water using its small head and very long neck to remain hidden," says lead author and UZH paleontologist Stephan Spiekman.

Two species living together

Tanystropheus remains have mainly been found at Monte San Giorgio on the border between Switzerland and Italy, a place so unique for its Triassic fossils that it has been declared a UNESCO World Heritage Site. Two types of Tanystropheus fossils are known from this location, one small and one large. Until now, these were believed to be the juveniles and adults of the same species.

However, the current study disproves this assumption. The reconstructed skull, belonging to a large specimen, is very different from the already known smaller skulls, particularly when it comes to its dentition. In order to see whether the small fossils actually belonged to young animals, the researchers looked at cross sections of limb bones from the smaller type of Tanystropheus. They found many growth rings which form when bone growth is drastically slowed down. "The number and distribution of the growth rings tells us that these smaller types were not young animals, as previously considered, but mature ones," says last author Torsten Scheyer. "This means that the small fossils belonged to a separate, smaller species of Tanystropheus."

Specialists in different food sources

According to Spiekman, these two closely related species had evolved to use different food sources in the same environment: "The small species likely fed on small shelled animals, like shrimp, in contrast to the large species which ate fish and squid." For the researchers, this is a really remarkable finding: "We expected the bizarre neck of Tanystropheus to be specialized for a single task, like the neck of a giraffe. But actually, it allowed for several lifestyles."

ANN ARBOR, Michigan -- When COVID-19 struck, health care pivoted hard. Any unnecessary procedures or appointments were postponed. For people with cancer, that pivot was particularly shattering.

"COVID-19 changed the face of health care in the United States virtually overnight. Oncologists were discussing with their patients whether the benefit of coming in for treatment outweighed the risk of being exposed to the virus in the health care setting," says Laila A. Gharzai, M.D., LLM, a radiation oncology resident at Michigan Medicine.

"It was a challenging shift for physicians, and we personally wanted some help navigating these conversations," she says.

In response, Gharzai and colleagues interviewed eight physicians to identify specific communication challenges related to COVID-19 and surveyed 48 patients to get their perspective.

They identified three core communication strategies and applied them to eight specific scenarios impacting patients, including concerns around risk of COVID-19, delays in testing or treatment, changes to treatment and follow-up care. Informed by the communication strategies, the team created examples of language that oncologists could use to respond to patients empathetically. Their results are published in JAMA Oncology.

"What impacted me most was hearing just how tough these conversations were. As oncologists, we are used to having tough conversations with our patients. COVID-related conversations took this to a whole other level, by incorporating a new challenge of having to view all of our decisions with a public health lens. This guide was important to give providers a quick resource when they needed it most," Gharzai says.

Patients' concerns ranged from their risk of getting coronavirus to fears that a delayed test could miss a growing cancer. Many patients felt they were being punished or ignored, as if their health needs were less important. And while the decisions were all made with a view toward keeping patients safe from the greater threat of COVID-19, cancer is not used to taking a backseat.

"Patients are understandably emotional when they receive a cancer diagnosis, even under normal circumstances. This emotional response was amplified by the stress of changes due to the pandemic," says Reshma Jagsi, M.D., D.Phil, Newman Family Professor and deputy chair of radiation oncology at Michigan Medicine and senior author on the paper.

"The practical language in the guide really helped me to reassure patients that I recognized their very appropriate emotions, that I care deeply about them, and that I was going to try to help," she says.

The team published their guidelines online in April, when COVID-19 was peaking in Michigan. It remains available to providers.

CAMBRIDGE, MA -- Several thousand strains of bacteria live in the human gut. Some of these are associated with disease, while others have beneficial effects on human health. Figuring out the precise role of each of these bacteria can be difficult, because many of them can't be grown in lab studies using human tissue.

This difficulty is especially pronounced for species that cannot live in oxygen-rich environments. However, MIT biological and mechanical engineers have now designed a specialized device in which they can grow those oxygen-intolerant bacteria in tissue that replicates the lining of the colon, allowing them to survive for up to four days.

"We thought it was really important to contribute a tool to the community that could be used for this extreme case," says Linda Griffith, the School of Engineering Professor of Teaching Innovation in MIT's Department of Biological Engineering. "We showed that you can grow these very fastidious organisms, and we were able to study the effects they have on the human colon."

Using this system, the researchers showed that they could grow a strain of bacteria called Faecalibacterium prausnitzii, which lives in the human gut and protects against inflammation. They also showed that these bacteria, which are often diminished in patients with Crohn's disease, appear to exert many of their protective effects through the release of a fatty acid called butyrate.

Griffith and David Trumper, an MIT professor of mechanical engineering, are the senior authors of the study, which appears today in the journal Med. MIT postdocs Jianbo Zhang and Yu-Ja Huang are the lead authors of the paper.

Oxygen sensitivity

The human gut's complex microbiome environment is difficult to model using animals such as mice, in part because mice eat a very different diet from humans, Griffith says.

"We've learned a huge amount from mice and other animal models, but there are a lot of differences, especially when it comes to the gut microbiome," she says.

Most of the bacteria that live in the human gut are anaerobic, meaning that they do not require oxygen to survive. Some of these bacteria can tolerate low levels of oxygen, while others, such as F. prausnitzii, cannot survive oxygen exposure, which makes it difficult to study them in a laboratory. Some researchers have designed devices in which they can grow human colon cells along with bacteria that tolerate low levels of oxygen, but these don't work well for F. prausnitzii and other highly oxygen-intolerant microbes.

To overcome this, the MIT team designed a device that allows them to precisely control oxygen levels in each part of the system. Their device contains a channel that is coated with cells from the human mucosal barrier of the colon. Below these cells, nutrients are pumped in to keep the cells alive. This bottom layer is oxygen-rich, but the concentration of oxygen decreases toward the top of the mucosal cell layer, similarly to what happens in the interior of the human colon.

Just as they do in the human colon, the barrier cells in the channel secrete a dense layer of mucus. The MIT team showed that F. prausnitzii can form clouds of cells in the outer layer of this mucus and survive there for up to four days, in an environment that is kept oxygen-free by fluid flowing across it. This fluid also contains nutrients for the microbes.

Using this system, the researchers were able to show that F. prausnitzii does influence cell pathways involved in inflammation. They observed that the bacteria produce a short-chain fatty acid called butyrate, which has previously been shown to reduce inflammation. After butyrate levels went up, the mucosal cells showed a reduction in the activity of a pathway called NF kappa B. This reduction calms inflammation.

"Overall, this pathway has been reduced, which is really similar to what people have seen in humans," Zhang says. "It seems that the bacteria are desensitizing the mammalian cells to not overreact to the dangers in the outside environment, so the inflammation status is being calmed down by the bacteria."

Patients with Crohn's disease often have reduced levels of F. prausnitzii, and the lack of those bacteria is hypothesized to contribute to the overactive inflammation seen in those patients.

When the researchers added butyrate to the system, without bacteria, it did not generate all of the effects that they saw when the bacteria were present. This suggests that some of the bacteria's effects may be exerted through other mechanisms, which the researchers hope to further investigate.

Microbes and disease

The researchers also plan to use their system to study what happens when they add other species of bacteria that are believed to play a role in Crohn's disease, to try to further explore the effects of each species.

They are also planning a study, working with Alessio Fasano, the division chief of pediatric gastroenterology and nutrition at Massachusetts General Hospital, to grow mucosal tissue from patients with celiac disease and other gastrointestinal disorders. This tissue could then be used to study microbe-induced inflammation in cells with different genetic backgrounds.

"We are hoping to get new data that will show how the microbes and the inflammation work with the genetic background of the host, to see if there could be people who have a genetic susceptibility to having microbes interfere with the mucosal barrier a little more than other people," Griffith says.

She also hopes to use the device to study other types of mucosal barriers, including those of the female reproductive tract, such as the cervix and the endometrium.