Cool new worlds found in our cosmic backyard

 How complete is our census of the Sun's closest neighbors? Astronomers using NSF's NOIRLab facilities and a team of data-sleuthing volunteers participating in Backyard Worlds: Planet 9, a citizen science project, have discovered roughly 100 cool worlds near the Sun -- objects more massive than planets but lighter than stars, known as brown dwarfs. Several of these newly discovered worlds are among the very coolest known, with a few approaching the temperature of Earth -- cool enough to harbor water clouds.

Discovering and characterizing astronomical objects near the Sun is fundamental to our understanding of our place in, and the history of, the Universe. Yet astronomers are still unearthing new residents of the Solar neighborhood. A remarkable breakthrough was announced today, with the discovery of roughly 100 cool brown dwarfs near the Sun.The new Backyard Worlds discoveries bridge a previously empty gap in the range of low-temperature brown dwarfs, identifying a long-sought missing link within the brown dwarf population.

"These cool worlds offer the opportunity for new insights into the formation and atmospheres of planets beyond the Solar System," said Aaron Meisner from the National Science Foundation's NOIRLab and the lead author of the research paper. "This collection of cool brown dwarfs also allows us to accurately estimate the number of free-floating worlds roaming interstellar space near the Sun."

This major advancement was made possible with archival data from the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory (KPNO) and the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO), which were made available through the Community Science and Data Center (CSDC), all programs of NSF's NOIRLab. Large survey data sets were then made available to the Backyard Worlds volunteers using NOIRLab's Astro Data Lab science platform. The results, to be published in TheAstrophysical Journal, demonstrate the rapidly growing role of survey and archival data research in astronomy today.

Brown dwarfs lie somewhere between the most massive planets and the smallest stars. Lacking the mass needed to sustain nuclear reactions in their core, brown dwarfs resemble cooling embers. Their low mass, low temperature and lack of internal nuclear reactions make them extremely faint -- and therefore extremely difficult to detect. Because of this, when searching for the very coolest brown dwarfs, astronomers can only hope to detect such objects relatively close to the Sun.

To help find our Sun's coldest and nearest neighbors, the astronomers of the Backyard Worlds project turned to a worldwide network of more than 100,000 citizen scientists. These volunteers diligently inspect trillions of pixels of telescope images to identify the subtle movements of brown dwarfs and planets. Despite the abilities of machine learning and supercomputers, there's no substitute for the human eye when it comes to scouring telescope images for moving objects.

The keen eyes of the Backyard Worlds volunteers have already discovered more than 1,500 cold worlds near to the Sun, and today's paper presents roughly 100 of the coldest in that sample. According to Meisner, this is a record for any citizen science program by a factor of about 20, and 20 citizen scientists are listed as co-authors of the study. A handful of these cool worlds -- which are among the very coldest brown dwarfs known -- approach the temperature of Earth. NASA's Spitzer Space Telescope provided the brown dwarf temperature estimates.

Brown dwarfs are expected to cool as they age, passing from near-stellar temperatures down to planetary temperatures and below, fading all the while and eventually winking out. The new discoveries attest to this picture by uncovering elusive examples of brown dwarfs approaching Earth-temperature.

"This paper is evidence that the solar neighborhood is still uncharted territory and citizen scientists are excellent astronomical cartographers," said co-author Jackie Faherty of the American Museum of Natural History. "Mapping the coldest brown dwarfs down to the lowest masses gives us key insights into the low-mass star formation process while providing a target list for detailed studies of the atmospheres of Jupiter analogs."

Citizen scientist, Astro Data Lab user, and paper co-author Jim Walla added, "It's awesome to know that our discoveries are now counted among the Sun's neighbors and will be targets of further research."

Alongside the dedicated efforts of the Backyard Worlds volunteers, NOIRLab's Astro Data Lab was instrumental in this research. The technical burden of downloading billion-object astronomical catalogs is typically insurmountable for individual investigators -- including most professional astronomers. "AstroData Lab's open and accessible web portal allowed Backyard Worlds citizen scientists to easily query massive catalogs for brown dwarf candidates," explained NOIRLab astronomer Stephanie Juneau, who helped introduce the citizen scientists to Astro Data Lab. Astro Data Lab also enables convenient matching between data sets from NOIRLab telescopes and external facilities, such as NASA's WISE satellite, that jointly contributed to these brown dwarf discoveries.

In addition to Astro Data Lab's making data accessible to the Backyard Worlds collaboration, archival observations by telescopes at two other NOIRLab Programs -- CTIO and KPNO -- were also key to this discovery. "Wide-area imaging from NOIRLab's Mayall and Blanco telescopes was also critical," explained Aaron Meisner. "To select only the very coldest brown dwarfs, we inspected deep images from a variety of sensitive astronomical surveys."

"It's great to see such thrilling results from NOIRLab's efforts to broaden participation in astronomy research," said Chris Davis of the National Science Foundation, the US agency that supports operations at the Kitt Peak and Cerro Tololo observatories and at CSDC. "By making archival data from NSF's Mayall and Blanco telescopes publicly available and easily accessible through CSDC, folks with a fascination for astronomy can make a real contribution to science and to our understanding of the Universe."

The approach of the Backyard Worlds project -- searching for rare objects in large data sets -- is also one of the goals for the upcoming Vera C. Rubin Observatory. Currently under construction on Cerro Pachón in the Chilean Andes, Rubin Observatory will image the visible sky from the southern hemisphere every three nights over ten years, providing a vast amount of data that will enable new ways of doing astrophysical research.

Read more at Science Daily

Smartphones can tell when you're drunk by analyzing your walk

 Your smartphone can tell when you've had too much to drink by detecting changes in the way you walk, according to a new study published in the Journal of Studies on Alcohol and Drugs.

Having real-time information about alcohol intoxication could be important for helping people reduce alcohol consumption, preventing drinking and driving or alerting a sponsor for someone in treatment, according to lead researcher Brian Suffoletto, M.D., who was with the University of Pittsburgh School of Medicine when the research was conducted and is now with Stanford University School of Medicine's Department of Emergency Medicine.

"We have powerful sensors we carry around with us wherever we go," Suffoletto says. "We need to learn how to use them to best serve public health."

But for Suffoletto, this research is much more than academic. "I lost a close friend to a drinking and driving crash in college," he says. "And as an emergency physician, I have taken care of scores of adults with injuries related to acute alcohol intoxication. Because of this, I have dedicated the past 10 years to testing digital interventions to prevent deaths and injury related to excessive alcohol consumption."

For the study, Suffoletto and colleagues recruited 22 adults ages 21 to 43. Volunteers came to a lab and received a mixed drink with enough vodka to produce a breath alcohol concentration of .20 percent. They had one hour to finish the alcohol.

Then hourly for seven hours, participants had their breath alcohol concentration analyzed and performed a walking task. For this task, researchers placed a smartphone on each participant's lower back, secured with an elastic belt. Participants walked a straight line for 10 steps, turned around, and walked back 10 steps.

The smartphones measured acceleration and mediolateral (side to side), vertical (up and down) and anteroposterior (forward and backward) movements while the participants walked.

About 90 percent of the time, the researchers were able to use changes in gait to identify when participants' breath alcohol concentration exceeded .08 percent, the legal limit for driving in the United States.

"This controlled lab study shows that our phones can be useful to identify 'signatures' of functional impairments related to alcohol," Suffoletto says.

Although placing the smartphone on the lower back does not reflect how people carry their cell phones in real life, the research group plans to conduct additional research while people carry phones in their hands and in their pockets.

And although it was a small investigation, the researchers write that this is a "proof-of-concept study" that "provides a foundation for future research on using smartphones to remotely detect alcohol-related impairments."

"In 5 years, I would like to imagine a world in which if people go out with friends and drink at risky levels," Suffoletto says, "they get an alert at the first sign of impairment and are sent strategies to help them stop drinking and protect them from high-risk events like driving, interpersonal violence and unprotected sexual encounters."

Read more at Science Daily

Flexible and protected

 In the fight against the coronavirus, SARS-CoV-2 researchers from multiple research institutions in Germany have combined their resources to study the spike protein on the surface of the virus. With its spikes, the virus binds to human cells and infects them. The study gave surprising insights into the spike protein, including an unexpected freedom of movement and a protective coat to hide it from antibodies. The results are published in Science.

At the start of a COVID-19 infection, the coronavirus SARS-CoV-2 docks onto human cells using the spike-like proteins on its surface. The spike protein is at the centre of vaccine development because it triggers an immune response in humans. A group of German scientists, including members of the European Molecular Biology Laboratory (EMBL) in Heidelberg, the Max Planck Institute of Biophysics, the Paul-Ehrlich-Institut, and Goethe University Frankfurt have focused on the surface structure of the virus to gain insights they can use for the development of vaccines and of effective therapeutics to treat infected patients.

The team combined cryo-electron tomography, subtomogram averaging, and molecular dynamics simulations to analyse the molecular structure of the spike protein in its natural environment, on intact virions, and with near-atomic resolution. Using EMBL's state-of-the-art cryo-electron microscopy imaging facility, 266 cryotomograms of about 1000 different viruses were generated, each carrying an average of 40 spikes on its surface. Subtomogram averaging and image processing, combined with molecular dynamics simulations, finally provided the important and novel structural information on these spikes.

The results were surprising: the data showed that the globular portion of the spike protein, which contains the receptor-binding region and the machinery required for fusion with the target cell, is connected to a flexible stalk. "The upper spherical part of the spike has a structure that is well reproduced by recombinant proteins used for vaccine development," explains Martin Beck, EMBL group leader and a director of the Max Planck Institute (MPI) of Biophysics. "However, our findings about the stalk, which fixes the globular part of the spike protein to the virus surface, were new."

"The stalk was expected to be quite rigid," adds Gerhard Hummer, from the MPI of Biophysics and the Institute of Biophysics at Goethe University Frankfurt. "But in our computer models and in the actual images, we discovered that the stalks are extremely flexible." By combining molecular dynamics simulations and cryo-electron tomography, the team identified the three joints -- hip, knee and ankle -- that give the stalk its flexibility.

Read more at Science Daily

Why doesn't Ebola cause disease in bats, as it does in people?

 A new study by researchers from The University of Texas Medical Branch at Galveston uncovered new information on why the Ebola virus can live within bats without causing them harm, while the same virus wreaks deadly havoc to people. This study is now available in Cell Reports.

The Ebola virus causes a devastating, often fatal, infectious disease in people. Within the past decade, Ebola has caused two large and difficult to control outbreaks, one of which recently ended in the Democratic Republic of the Congo.

When a virus brings serious disease to people, it means that humans are not good hosts for the virus. Viruses depend on a living host for their survival and have natural reservoirs -- a hosting animal species in which a virus naturally lives and reproduces without causing disease. Bats are likely a natural reservoir for the Ebola virus, but little is known about how the virus evolves in bats.

Like most other RNA viruses, Ebola's molecules are structured in a way that makes them more prone to genomic errors and mutations than other types of viruses. Because of this, Ebola and similar viruses have a remarkable ability to adapt to and replicate in new environments.

In the study, the research team, led by Alex Bukreyev, a UTMB virologist in the departments of pathology and microbiology and immunology, working with the team of Raul Andino, University of California, San Francisco, investigated how the Ebola virus adapts to both bat and human cells. They assessed changes in mutation rates and the structure of Ebola virus populations repeatedly in both bat and human cell lines using an ultra-deep genetic sequencing.

"We identified a number of meaningful differences in how the Ebola virus evolves when placed in a human cell line relative to a bat cell line," Bukreyev said. "For instance, the RNA editing enzyme called ADAR within bat cells play a greater role in the replication and evolution of the Ebola virus than do such enzymes in human cells. We found that the envelope protein of Ebola virus undergoes a drastic increase in certain mutations within bat cells, but this was not found in human cells. This study identifies a novel mechanism by which Ebola virus is likely to evolve in bats."

Read more at Science Daily

Ocean microbes could interact with pollution to influence climate

 Oceans cover almost three-quarters of the globe, yet little is known about how gases and aerosols made by ocean microbes affect weather and climate, or how human-produced pollution could influence this process. Now, scientists report they've used an "ocean-in-a-lab" to show that air pollution can change the makeup of gases and aerosols that sea spray releases into the atmosphere and, in turn, potentially alter weather patterns.

The researchers will present their results today at the American Chemical Society (ACS) Fall 2020 Virtual Meeting & Expo.

"It's surprising that we don't know more about the central role of ocean microbes in controlling climate," says Kimberly Prather, Ph.D., the project's principal investigator. "They have the potential to influence atmospheric composition, cloud formation and weather. Humans can alter these natural processes in two ways: by changing the microbial community structure in the ocean, and by producing air pollutants that react with compounds that the microorganisms produce."

Through natural biological processes, ocean microbes -- including bacteria, phytoplankton and viruses -- produce compounds that enter the atmosphere as gases or aerosols (tiny water droplets or particles in air that form when waves crash). In addition, the microorganisms themselves can be ejected from the ocean in the form of aerosolized droplets. Some of these particles can seed clouds, absorb or reflect sunlight, or otherwise influence atmospheric conditions and weather.

"There's a standard belief that one way the ocean can regulate the temperature of the planet is through emission of gases and particles," says Prather, who is at the Scripps Institution of Oceanography at the University of California San Diego. "Some scientists refer to the ocean as the 'planetary thermostat.'"

Prather and colleagues wondered how humans might influence this thermostat. But first, they needed to learn how ocean microbes affect climate without humans. To find out, the researchers built a 108-foot-long wave channel and filled it with 3,400 gallons of seawater. They caused a phytoplankton bloom -- an overgrowth of microscopic algae that occurs naturally in oceans -- under certain conditions -- in this ocean-in-a-lab. They continuously monitored the gases and aerosols produced in the air above the water, measuring things such as aerosol size, composition, shape, enzymatic activity and pH. They also studied how natural changes in the microbial community, for example, introducing certain species of bacteria and phytoplankton, affected the cloud-forming potential of the aerosols. "The short answer is that the biology had very little effect on sea spray aerosol composition," Prather says. "Altering natural biological processes in seawater resulted in a very small change in the ability of the primary particles to form cloud droplets."

In contrast, adding a small amount of an atmospheric oxidant (hydroxyl radical, which can be generated naturally and can be enhanced in polluted atmospheres) caused an immediate shift in the composition and cloud-forming potential of marine aerosols. According to Prather, the oxidant reacted with microbe-produced gases in the air, transforming them into compounds that changed the composition of the primary sea spray aerosol and formed new types of particles. Although the researchers don't know yet how other individual pollutants affect sea spray aerosols, Prather says that it's important to study the complete gas phase mixture of pollutants to mimic and understand real-world chemical reactions.

Read more at Science Daily

Cosmic gas cloud blinks in sync with circling black hole

 Scientists have detected a mysterious gamma-ray heartbeat coming from a cosmic gas cloud. The inconspicuous cloud in the constellation Aquila is beating with the rhythm of a neighbouring precessing black hole, indicating a connection between the two objects, as the team led by DESY Humboldt Fellow Jian Li and ICREA Professor Diego F. Torres from the Institute of Space Sciences (IEEC-CSIC) reports in the journal Nature Astronomy. Just how the black hole powers the cloud's gamma-ray heartbeat over a distance of about 100 light years remains enigmatic.

The research team, comprising scientists from Germany, Spain, China and the U.S., rigorously analysed more than ten years of data from the US space administration NASA's Fermi gamma-ray space telescope, looking at a so-called micro quasar. The system catalogued as SS 433 is located some 15,000 lightyears away in the Milky Way and consists of a giant star with about 30 times the mass of our sun and a black hole with about 10 to 20 solar masses. The two objects are orbiting each other with a period of 13 days, while the black hole sucks matter from the giant star.

"This material accumulates in an accretion disc before falling into the black hole, like water in the whirl above the drain of a bath tub," explains Li. "However, a part of that matter does not fall down the drain but shoots out at high speed in two narrow jets in opposite directions above and below the rotating accretion disk." This setting is known from active galaxies called quasars with monstrous black holes with millions of solar masses at their centres that shoot jets tens of thousands of lightyears into the cosmos. As SS 433 looks like a scaled-down version of these quasars, it has been dubbed a micro quasar.

The high-speed particles and the ultra-strong magnetic fields in the jet produce X-rays and gamma rays. "The accretion disc does not lie exactly in the plane of the orbit of the two objects. It precesses, or sways, like a spinning top that has been set up slanted on a table," says Torres. "As a consequence, the two jets spiral into the surrounding space, rather than just forming a straight line."

The precession of the black hole's jets has a period of about 162 days. Meticulous analysis revealed a gamma-ray signal with the same period from a position located relatively far from the micro quasar's jets, which has been labelled as Fermi J1913+0515 by the scientists. It is located at the position of an unremarkable gas enhancement. The consistent periods indicate the gas cloud's emission is powered by the micro quasar.

"Finding such an unambiguous connection via timing, about 100 light years away from the micro quasar, not even along the direction of the jets is as unexpected as amazing," says Li. "But how the black hole can power the gas cloud's heartbeat is unclear to us." Direct periodic illumination by the jet seems unlikely. An alternative that the team explored is based on the impact of fast protons (the nuclei of hydrogen atoms) produced at the ends of the jets or near the black hole, and injected into the cloud, where these subatomic particles hit the gas and produce gamma rays. Protons could also be part of an outflow of fast particles from the edge of the accretion disc. Whenever this outflow strikes the gas cloud, it lights up in gamma rays, which would explain its strange heartbeat. "Energetically, the outflow from the disc could be as powerful as that of the jets and is believed to precess in solidarity with the rest of the system," explains Torres.

 Read more at Science Daily

Widespread electric vehicle adoption would save billions of dollars, thousands of lives

 Northwestern University researchers have combined climate modeling with public health data to evaluate the impact of electric vehicles (EVs) on U.S. lives and the economy.

A new study found that if EVs replaced 25% of combustion-engine cars currently on the road, the United States would save approximately $17 billion annually by avoiding damages from climate change and air pollution. In more aggressive scenarios -- replacing 75% of cars with EVs and increasing renewable energy generation -- savings could reach as much as $70 billion annually.

"Vehicle electrification in the United States could prevent hundreds to thousands of premature deaths annually while reducing carbon emissions by hundreds of millions of tons," said Daniel Peters, who led the study. "This highlights the potential of co-beneficial solutions to climate change that not only curb greenhouse gas emissions but also reduce the health burden of harmful air pollution."

"From an engineering and technological standpoint, people have been developing solutions to climate change for years," added Northwestern's Daniel Horton, senior author of the study. "But we need to rigorously assess these solutions. This study presents a nuanced look at EVs and energy generation and found that EV adoption not only reduces greenhouse gases but saves lives."

The study was published online last week (August 13) in the journal GeoHealth.

During this research, Peters was an undergraduate researcher in Horton's laboratory at Northwestern. He now works for the Environmental Defense Fund. Horton is an assistant professor of Earth and planetary sciences in Northwestern's Weinberg College of Arts and Sciences.

To conduct the study, Horton, Peters and their team looked at vehicle fleet and emissions data from 2014. If 25% of U.S. drivers adopted EVs in 2014 -- and the power required to charge their batteries came from 2014's energy generation infrastructure -- then 250 million tons of carbon dioxide (CO2) emissions would have been mitigated. Although the impact of carbon emissions on the climate is well documented, combustion engines also produce other harmful pollutants, such as particulate matter and the precursors to ground-level ozone. Such pollutants can trigger a variety of health problems, including asthma, emphysema, chronic bronchitis and ultimately premature death.

After leaving tailpipes and smokestacks, pollutants interact with their environment, including background chemistry and meteorology.

"A good example is to look at nitrogen oxides (NOx), a group of chemicals produced by fossil-fuel combustion," Peters explained. "NOx itself is damaging to respiratory health, but when it's exposed to sunlight and volatile organic compounds in the atmosphere, ozone and particulate matter can form."

To account for these interactions, the researchers used a chemistry-climate model developed at the Geophysical Fluid Dynamics Laboratory. Jordan Schnell, a postdoctoral fellow in Horton's lab, performed the model experiments that simultaneously simulate the atmosphere's weather and chemistry, including how emissions from combustion engines and power generation sources interact with each other and other emissions sources in their environments.

With this model, the researchers simulated air pollutant changes across the lower 48 states, based on different levels of EV adoption and renewable energy generation. Then, they combined this information with publicly available county health data from the U.S. Environmental Protection Agency (EPA). This combination enabled the research team to assess health consequences from the air quality changes caused by each electrification scenario.

The research team assigned dollar values to the avoided climate and health damages that could be brought about by EV adoption by applying the social cost of carbon and value of statistical life metrics to their emission change results. These commonly used policy tools attach a price tag to long-term health, environmental and agricultural damages.

 Read more at Science Daily

Survival of the fit-ish

 It can be hard to dispute the common adage 'survival of the fittest'. After all, "most of the genes in the genome are there because they're doing something good," says Sarah Zanders, PhD, assistant investigator at the Stowers Institute for Medical Research. But, she says, "others are just there because they've figured out a way to be there."

The conventional understanding of evolution is that genes encoding a beneficial function are the most frequently transmitted, which ensures that the fittest organisms -- the ones that have traits most favorable for their environment -- survive. Less known is the fact that there exist parasitic gene elements within an organism that are doing just the opposite.

"The way one could think of it is that the genome is like a society," explains Zanders. "Within that society, there are individuals who derive their living from doing good things and making valuable contributions. But there are others who don't contribute in beneficial ways and are actually harmful to society," explains Zanders.

The Zanders Lab studies parasitic genes in Schizosaccharomyces pombe, a species of fission yeast sometimes found in the popular fermented tea drink kombucha. Because of its simplicity and fast generation times, S. pombe is a highly tractable system for studying parasitic gene elements, particularly a class known as meiotic drivers. Instead of conferring a benefit to their host, meiotic drivers confer distinct disadvantages to their host, in order to bias their own perpetuation. One method of doing so, employed by the wtf meiotic drive genes, is through selective poisoning of cells in meiosis.

Meiosis is the process of cell division through which sexually-reproducing organisms form gametes -- such as egg and sperm cells in humans, or spores in yeast -- to propagate the next generation. Normally, this process results in gametes that inherit one of two copies of each chromosome carried by the parent cell, and each copy is transmitted to gametes at an equal rate. Meiotic drivers, however, short-circuit this law of Mendelian segregation.

"Usually all the alleles -- or variants of a particular gene -- get a fair chance, and natural selection can pick the best ones," explains Zanders. "But alleles that are meiotic drivers select themselves even if they're not the best option. And they're never the best option."

In a paper published online August 13, 2020, in eLife, members of the Zanders lab explain how it could be possible that meiotic drivers persist in the population, even as they kill off many would-be hosts. It turns out that S. pombe can employ variants of other genes to help suppress the negative effect of meiotic drivers, albeit at a cost to fitness.

Usually, to propagate laboratory strains of S. pombe, they are inbred. "When you outcross two isolates that are almost identical, they produce almost no progeny," explains first author María Angélica Bravo Núñez, PhD, who was involved in the identification of the wtf genes, and who did this work in the Zanders Lab as a predoctoral researcher at the Graduate School of the Stowers Institute. "This suggested there might be some type of competition at play." Bravo Núñez and colleagues used this reasoning to seek out genes that could be in conflict in similar, but non-identical, genomes of S. pombe. The central experimental design of the current work involved outcrossing of S. pombe isolates that are over 99% identical.

"Outcrossing can have many advantages," says Bravo Núñez, such as providing a normal allele of a gene to rescue the effect of a mutant allele. "But the meiotic drive genes that we study actually exert their deleterious effect in the heterozygous scenario, where the alleles of a gene are not the same."

One illuminating experiment they did was to compare outcomes of inbred and outcrossed S. pombe isolates in a genetic background containing a mutation in rec12, which is a gene that promotes proper chromosome segregation.

"Rec12 usually promotes fertility," says Bravo Núñez. "When we removed rec12 function, the numbers of viable spores decreased, but only in the inbred scenario. The relative numbers of viable spores didn't really decrease in the outcrossed scenario." Moreover, of the viable spores, they found that survival was biased towards atypical gamete products, resulting from mis-segregation and unequal crossover of paired chromosomes. In other words, surviving spores contained the maximal number of meiotic drivers, sometimes due to inheriting an extra chromosome. This finding was surprising because extra chromosomes are usually considered very harmful. In humans, for instance, extra or missing chromosomes can lead to inviable gametes, severe birth defects, or infertility.

"When you have heterozygosity of wtf genes, making a mutation in the rec12 gene is relatively good for the organism, because that's just what has to happen in order to not kill all the progeny," says Bravo Núñez.

"We think of rec12 as this gene that's really important for fertility," explains Zanders. "But the situation is totally different when there is outcrossing. Having rec12 doesn't actually help at all, because the yeast is better off making gametes that do not result from proper chromosome segregation. This is just one example of the power of meiotic drivers to change the landscape of meiosis. Fundamentally, what is 'good' for the organism has changed."

"Having that extra chromosome is not good, and the yeast colonies look unusual, small, and irregular. But after they continue to grow for a while, the cells lose that extra chromosome and then they can thrive as haploids. So, this step is actually just temporary," says Bravo Núñez.

Precisely because meiotic drivers exert their influence in a heterozygous scenario, they are easy to miss. "There are many flavors of meiotic drive. Some forms of meiotic drive are hard to measure experimentally because the bias is so subtle," says Zanders. "We're not the first to study meiotic drivers in depth. We just have a better model system now, so we can make more progress faster."

"Drive systems tend to be repetitive, and you can usually find them in various copies in genomes," says Bravo Núñez. "They have, in many cases, already been found in other systems, such as fungi, mice, and fruit flies, but are not yet fully characterized." The study of meiotic drivers in S. pombe "will hopefully guide future research to understand other drive systems."

"Humans certainly have meiotic drive genes. Whether or not they have meiotic drive genes of the gamete-killing type is unclear," says Zanders. "Meiotic drive has likely affected the evolution of human centromeres, which are regions of chromosomes that are very important for proper chromosome segregation. Certain chromosome fusions exhibit meiotic drive in humans, as do sequences that are involved in DNA recombination. We're going to continue focusing on these and other parasitic gene elements, their strategies, and their effects."

Read more at Science Daily

Social connection is the strongest protective factor for depression

 Researchers from Massachusetts General Hospital (MGH) have identified a set of modifiable factors from a field of over 100 that could represent valuable targets for preventing depression in adults. In a study published in The American Journal of Psychiatry, the team named social connection as the strongest protective factor for depression, and suggested that reducing sedentary activities such as TV watching and daytime napping could also help lower the risk of depression.

"Depression is the leading cause of disability worldwide, but until now researchers have focused on only a handful of risk and protective factors, often in just one or two domains," says Karmel Choi, PhD, investigator in the Department of Psychiatry and the Harvard T.H. Chan School of Public Health, and lead author of the paper. "Our study provides the most comprehensive picture to date of modifiable factors that could impact depression risk."

To that end, researchers took a two-stage approach. The first stage drew on a database of over 100,000 participants in the UK Biobank -- a world-renowned cohort study of adults -- to systematically scan a wide range of modifiable factors that might be associated with the risk of developing depression, including social interaction, media use, sleep patterns, diet, physical activity, and environmental exposures. This method, known as an exposure-wide association scan (ExWAS), is analogous to genome-wide association studies (GWAS) that have been widely used to identify genetic risk factors for disease. The second stage took the strongest modifiable candidates from ExWAS and applied a technique called Mendelian randomization (MR) to investigate which factors may have a causal relationship to depression risk. MR is a statistical method that treats genetic variation between people as a kind of natural experiment to determine whether an association is likely to reflect causation rather than just correlation.

This two-stage approach allowed the MGH researchers to narrow the field to a smaller set of promising and potentially causal targets for depression. "Far and away the most prominent of these factors was frequency of confiding in others, but also visits with family and friends, all of which highlighted the important protective effect of social connection and social cohesion," points out Jordan Smoller, MD, ScD associate chief for research in the MGH Department of Psychiatry, and senior author of the study. "These factors are more relevant now than ever at a time of social distancing and separation from friends and family." The protective effects of social connection were present even for individuals who were at higher risk for depression as a result of genetic vulnerability or early life trauma.

On the other hand, factors associated with depression risk included time spent watching TV, though the authors note that additional research is needed to determine if that risk was due to media exposure per se or whether time in front of the TV was a proxy for being sedentary. Perhaps more surprising, the tendency for daytime napping and regular use of multivitamins appeared to be associated with depression risk, though more research is needed to determine how these might contribute.

Read more at Science Daily

Inexpensive, accessible device provides visual proof that masks block droplets

 

  Duke physician Eric Westman was one of the first champions of masking as a means to curtail the spread of coronavirus, working with a local non-profit to provide free masks to at-risk and under-served populations in the greater Durham community.

But he needed to know whether the virus-blocking claims mask suppliers made were true, to assure he wasn't providing ineffective masks that spread viruses along with false security. So he turned to colleagues in the Duke Department of Physics: Could someone test various masks for him?

Martin Fischer, Ph.D., a chemist and physicist, stepped up. As director of the Advanced Light Imaging and Spectroscopy facility, he normally focuses on exploring new optical contrast mechanisms for molecular imaging, but for this task, he MacGyvered a relatively inexpensive apparatus from common lab materials that can easily be purchased online. The setup consisted of a box, a laser, a lens, and a cell phone camera.

In a proof-of-concept study appearing online Aug. 7 in the journal Science Advances, Fischer, Westman and colleagues report that the simple, low-cost technique provided visual proof that face masks are effective in reducing droplet emissions during normal wear.

"We confirmed that when people speak, small droplets get expelled, so disease can be spread by talking, without coughing or sneezing," Fischer said. "We could also see that some face coverings performed much better than others in blocking expelled particles."

Notably, the researchers report, the best face coverings were N95 masks without valves -- the hospital-grade coverings that are used by front-line health care workers. Surgical or polypropylene masks also performed well.

But hand-made cotton face coverings provided good coverage, eliminating a substantial amount of the spray from normal speech.

On the other hand, bandanas and neck fleeces such as balaclavas didn't block the droplets much at all.

"This was just a demonstration -- more work is required to investigate variations in masks, speakers, and how people wear them -- but it demonstrates that this sort of test could easily be conducted by businesses and others that are providing masks to their employees or patrons," Fischer said.

"Wearing a mask is a simple and easy way to reduce the spread of COVID-19," Westman said. "About half of infections are from people who don't show symptoms, and often don't know they're infected. They can unknowingly spread the virus when the cough, sneeze and just talk.

"If everyone wore a mask, we could stop up to 99% of these droplets before they reach someone else," Westman said. "In the absence of a vaccine or antiviral medicine, it's the one proven way to protect others as well as yourself."

Westman and Fischer said it's important that businesses supplying masks to the public and employees have good information about the products they're providing to assure the best protection possible.

"We wanted to develop a simple, low-cost method that we could share with others in the community to encourage the testing of materials, masks prototypes and fittings," Fischer said. "The parts for the test apparatus are accessible and easy to assemble, and we've shown that they can provide helpful information about the effectiveness of masking."

Westman said he put the information immediately to use: "We were trying to make a decision on what type of face covering to purchase in volume, and little information was available on these new materials that were being used."

Read more at Science Daily