Saturn moon, Enceladus, could support life in its subsurface ocean

 Using data from NASA's Cassini spacecraft, scientists at Southwest Research Institute (SwRI) modeled chemical processes in the subsurface ocean of Saturn's moon Enceladus. The studies indicate the possibility that a varied metabolic menu could support a potentially diverse microbial community in the liquid water ocean beneath the moon's icy facade.

Prior to its deorbit in September of 2017, Cassini sampled the plume of ice grains and water vapor erupting from cracks on the icy surface of Enceladus, discovering molecular hydrogen, a potential food source for microbes. A new paper published in the planetary science journal Icarus explores other potential energy sources.

"The detection of molecular hydrogen (H2) in the plume indicated that there is free energy available in the ocean of Enceladus," said lead author Christine Ray, who works part time at SwRI as she pursues a Ph.D. in physics from The University of Texas at San Antonio. "On Earth, aerobic, or oxygen-breathing, creatures consume energy in organic matter such as glucose and oxygen to create carbon dioxide and water. Anaerobic microbes can metabolize hydrogen to create methane. All life can be distilled to similar chemical reactions associated with a disequilibrium between oxidant and reductant compounds."

This disequilibrium creates a potential energy gradient, where redox chemistry transfers electrons between chemical species, most often with one species undergoing oxidation while another species undergoes reduction. These processes are vital to many basic functions of life, including photosynthesis and respiration. For example, hydrogen is a source of chemical energy supporting anaerobic microbes that live in the Earth's oceans near hydrothermal vents. At Earth's ocean floor, hydrothermal vents emit hot, energy-rich, mineral-laden fluids that allow unique ecosystems teeming with unusual creatures to thrive. Previous research found growing evidence of hydrothermal vents and chemical disequilibrium on Enceladus, which hints at habitable conditions in its subsurface ocean.

"We wondered if other types of metabolic pathways could also provide sources of energy in Enceladus' ocean," Ray said. "Because that would require a different set of oxidants that we have not yet detected in the plume of Enceladus, we performed chemical modeling to determine if the conditions in the ocean and the rocky core could support these chemical processes."

For example, the authors looked at how ionizing radiation from space could create the oxidants O2 and H2O2, and how abiotic geochemistry in the ocean and rocky core could contribute to chemical disequilibria that might support metabolic processes. The team considered whether these oxidants could accumulate over time if reductants are not present in appreciable amounts. They also considered how aqueous reductants or seafloor minerals could convert these oxidants into sulfates and iron oxides.

"We compared our free energy estimates to ecosystems on Earth and determined that, overall, our values for both aerobic and anaerobic metabolisms meet or exceed minimum requirements," Ray said. "These results indicate that oxidant production and oxidation chemistry could contribute to supporting possible life and a metabolically diverse microbial community on Enceladus."

"Now that we've identified potential food sources for microbes, the next question to ask is 'what is the nature of the complex organics that are coming out of the ocean?'" said SwRI Program Director Dr. Hunter Waite, a coauthor of the new paper, referencing an online Nature paper authored by Postberg et al. in 2018. "This new paper is another step in understanding how a small moon can sustain life in ways that completely exceed our expectations!"

The paper's findings also have great significance for the next generation of exploration.

Read more at Science Daily

Dark storm on Neptune reverses direction, possibly shedding a fragment

 Astronomers using NASA's Hubble Space Telescope watched a mysterious dark vortex on Neptune abruptly steer away from a likely death on the giant blue planet.

The storm, which is wider than the Atlantic Ocean, was born in the planet's northern hemisphere and discovered by Hubble in 2018. Observations a year later showed that it began drifting southward toward the equator, where such storms are expected to vanish from sight. To the surprise of observers, Hubble spotted the vortex change direction by August 2020, doubling back to the north. Though Hubble has tracked similar dark spots over the past 30 years, this unpredictable atmospheric behavior is something new to see.

Equally as puzzling, the storm was not alone. Hubble spotted another, smaller dark spot in January this year that temporarily appeared near its larger cousin. It might possibly have been a piece of the giant vortex that broke off, drifted away, and then disappeared in subsequent observations.

"We are excited about these observations because this smaller dark fragment is potentially part of the dark spot's disruption process," said Michael H. Wong of the University of California at Berkeley. "This is a process that's never been observed. We have seen some other dark spots fading away, and they're gone, but we've never seen anything disrupt, even though it's predicted in computer simulations."

The large storm, which is 4,600 miles across, is the fourth dark spot Hubble has observed on Neptune since 1993. Two other dark storms were discovered by the Voyager 2 spacecraft in 1989 as it flew by the distant planet, but they had disappeared before Hubble could observe them. Since then, only Hubble has had the sharpness and sensitivity in visible light to track these elusive features, which have sequentially appeared and then faded away over a duration of about two years each. Hubble uncovered this latest storm in September 2018.

Wicked Weather

Neptune's dark vortices are high-pressure systems that can form at mid-latitudes and may then migrate toward the equator. They start out remaining stable due to Coriolis forces, which cause northern hemisphere storms to rotate clockwise, due to the planet's rotation. (These storms are unlike hurricanes on Earth, which rotate counterclockwise because they are low-pressure systems.) However, as a storm drifts toward the equator, the Coriolis effect weakens and the storm disintegrates. In computer simulations by several different teams, these storms follow a more-or-less straight path to the equator, until there is no Coriolis effect to hold them together. Unlike the simulations, the latest giant storm didn't migrate into the equatorial "kill zone."

"It was really exciting to see this one act like it's supposed to act and then all of a sudden it just stops and swings back," Wong said. "That was surprising."

Dark Spot Jr.

The Hubble observations also revealed that the dark vortex's puzzling path reversal occurred at the same time that a new spot, informally deemed "dark spot jr.," appeared. The newest spot was slightly smaller than its cousin, measuring about 3,900 miles across. It was near the side of the main dark spot that faces the equator -- the location that some simulations show a disruption would occur.

However, the timing of the smaller spot's emergence was unusual. "When I first saw the small spot, I thought the bigger one was being disrupted," Wong said. "I didn't think another vortex was forming because the small one is farther towards the equator. So it's within this unstable region. But we can't prove the two are related. It remains a complete mystery.

"It was also in January that the dark vortex stopped its motion and started moving northward again," Wong added. "Maybe by shedding that fragment, that was enough to stop it from moving towards the equator."

The researchers are continuing to analyze more data to determine whether remnants of dark spot jr. persisted through the rest of 2020.

Dark Storms Still Puzzling

It's still a mystery how these storms form, but this latest giant dark vortex is the best studied so far. The storm's dark appearance may be due to an elevated dark cloud layer, and it could be telling astronomers about the storm's vertical structure.

Another unusual feature of the dark spot is the absence of bright companion clouds around it, which were present in Hubble images taken when the vortex was discovered in 2018. Apparently, the clouds disappeared when the vortex halted its southward journey. The bright clouds form when the flow of air is perturbed and diverted upward over the vortex, causing gases to likely freeze into methane ice crystals. The lack of clouds could be revealing information on how spots evolve, say researchers.

Weather Eye on the Outer Planets

Hubble snapped many of the images of the dark spots as part of the Outer Planet Atmospheres Legacy (OPAL) program, a long-term Hubble project, led by Amy Simon of NASA's Goddard Space Flight Center in Greenbelt, Maryland, that annually captures global maps of our solar system's outer planets when they are closest to Earth in their orbits.

OPAL's key goals are to study long-term seasonal changes, as well as capture comparatively transitory events, such as the appearance of dark spots on Neptune or potentially Uranus. These dark storms may be so fleeting that in the past some of them may have appeared and faded during multi-year gaps in Hubble's observations of Neptune. The OPAL program ensures that astronomers won't miss another one.

Read more at Science Daily

Genes could be key to new COVID-19 treatments, study finds

 Potential treatments for Covid-19 have been identified after the discovery of five genes associated with the most severe form of the disease.

Genetic evidence is second only to clinical trials as a way to tell which treatments will be effective in a disease. Existing drugs that target the actions of the genes reveal which drugs should be repurposed to treat Covid-19 in clinical trials, experts say.

Genes involved in two molecular processes -- antiviral immunity and lung inflammation -- were pinpointed. The breakthrough will help doctors understand how Covid-19 damages lungs at a molecular level.

Researchers from the University of Edinburgh made the discovery by studying the DNA of 2,700 patients in 208 intensive care units (ICUs) in the UK.

Researchers from the GenOMICC consortium -- a global collaboration to study genetics in critical illness -- compared the genetic information of Covid-19 patients in ICU with samples provided by healthy volunteers from other studies, such as UK Biobank, Generation Scotland and 100,000 Genomes.

The team found key differences in five genes of the ICU patients compared with samples provided by healthy volunteers. The genes -- IFNAR2, TYK2, OAS1, DPP9 and CCR2 -- partially explain why some people become desperately sick with Covid-19, while others are not affected.

Having highlighted the genes, the team were then able to predict the effect of drug treatments on patients, because some genetic variants respond in a similar way to particular drugs.

For example, they showed that a reduction in the activity of the TYK2 gene protects against Covid-19. A class of anti-inflammatory drugs called JAK inhibitors, which includes the drug baricitinib, produces this effect.

They also discovered that a boost in the activity of the gene INFAR2 is also likely to create protection, because it is likely to mimic the effect of treatment with interferon -- proteins released by cells of the immune system to defend against viruses. However, experts caution that to be effective, patients might need the treatment early in disease.

Based on the findings published in Nature, the researchers say that clinical trials should focus on drugs that target these specific antiviral and anti-inflammatory pathways.

Dr Kenneth Baillie, the project's chief investigator and Academic Consultant in Critical Care Medicine and Senior Research Fellow at University of Edinburgh's Roslin Institute, said: "This is a stunning realisation of the promise of human genetics to help understand critical illness. Just like in sepsis and influenza, in Covid-19, damage to the lungs is caused by our own immune system, rather than the virus itself. Our genetic results provide a roadmap through the complexity of immune signals, showing the route to key drug targets.

"Our results immediately highlight which drugs should be at the top of the list for clinical testing. We can only test a few drugs at a time, so making the right choices will save thousands of lives.

"This work is only possible because of the generous contribution of the patients themselves and their families, research teams in NHS hospitals across the country, and the generous funding we've received from the public and organisations."

GenOMICC (Genetics of Susceptibility and Mortality in Critical Care) started in 2015 as an open, global consortium of intensive care clinicians dedicated to understanding genetic factors that influence outcomes in intensive care from diseases such as SARS, influenza and sepsis. Throughout 2020 it has been focused on Covid-19 research in partnership with Genomics England.

This study is one of a number of COVID-19 studies that have been given urgent public health research status by the Chief Medical Officer and Deputy Chief Medical Officer for England.

Read more at Science Daily

New type of atomic clock keeps time even more precisely

 

Clock and abstract background.

Atomic clocks are the most precise timekeepers in the world. These exquisite instruments use lasers to measure the vibrations of atoms, which oscillate at a constant frequency, like many microscopic pendulums swinging in sync. The best atomic clocks in the world keep time with such precision that, if they had been running since the beginning of the universe, they would only be off by about half a second today.

Still, they could be even more precise. If atomic clocks could more accurately measure atomic vibrations, they would be sensitive enough to detect phenomena such as dark matter and gravitational waves. With better atomic clocks, scientists could also start to answer some mind-bending questions, such as what effect gravity might have on the passage of time and whether time itself changes as the universe ages.

Now a new kind of atomic clock designed by MIT physicists may enable scientists explore such questions and possibly reveal new physics.

The researchers report in the journal Nature that they have built an atomic clock that measures not a cloud of randomly oscillating atoms, as state-of-the-art designs measure now, but instead atoms that have been quantumly entangled. The atoms are correlated in a way that is impossible according to the laws of classical physics, and that allows the scientists to measure the atoms' vibrations more accurately.

The new setup can achieve the same precision four times faster than clocks without entanglement.

"Entanglement-enhanced optical atomic clocks will have the potential to reach a better precision in one second than current state-of-the-art optical clocks," says lead author Edwin Pedrozo-Peñafiel, a postdoc in MIT's Research Laboratory of Electronics.

If state-of-the-art atomic clocks were adapted to measure entangled atoms the way the MIT team's setup does, their timing would improve such that, over the entire age of the universe, the clocks would be less than 100 milliseconds off.

The paper's other co-authors from MIT are Simone Colombo, Chi Shu, Albert Adiyatullin, Zeyang Li, Enrique Mendez, Boris Braverman, Akio Kawasaki, Saisuke Akamatsu, Yanhong Xiao, and Vladan Vuletic, the Lester Wolfe Professor of Physics.

Time limit

Since humans began tracking the passage of time, they have done so using periodic phenomena, such as the motion of the sun across the sky. Today, vibrations in atoms are the most stable periodic events that scientists can observe. Furthermore, one cesium atom will oscillate at exactly the same frequency as another cesium atom.

To keep perfect time, clocks would ideally track the oscillations of a single atom. But at that scale, an atom is so small that it behaves according to the mysterious rules of quantum mechanics: When measured, it behaves like a flipped coin that only when averaged over many flips gives the correct probabilities. This limitation is what physicists refer to as the Standard Quantum Limit.

"When you increase the number of atoms, the average given by all these atoms goes toward something that gives the correct value," says Colombo.

This is why today's atomic clocks are designed to measure a gas composed of thousands of the same type of atom, in order to get an estimate of their average oscillations. A typical atomic clock does this by first using a system of lasers to corral a gas of ultracooled atoms into a trap formed by a laser. A second, very stable laser, with a frequency close to that of the atoms' vibrations, is sent to probe the atomic oscillation and thereby keep track of time.

And yet, the Standard Quantum Limit is still at work, meaning there is still some uncertainty, even among thousands of atoms, regarding their exact individual frequencies. This is where Vuletic and his group have shown that quantum entanglement may help. In general, quantum entanglement describes a nonclassical physical state, in which atoms in a group show correlated measurement results, even though each individual atom behaves like the random toss of a coin.

The team reasoned that if atoms are entangled, their individual oscillations would tighten up around a common frequency, with less deviation than if they were not entangled. The average oscillations that an atomic clock would measure, therefore, would have a precision beyond the Standard Quantum Limit.

Entangled clocks

In their new atomic clock, Vuletic and his colleagues entangle around 350 atoms of ytterbium, which oscillates at the same very high frequency as visible light, meaning any one atom vibrates 100,000 times more often in one second than cesium. If ytterbium's oscillations can be tracked precisely, scientists can use the atoms to distinguish ever smaller intervals of time.

The group used standard techniques to cool the atoms and trap them in an optical cavity formed by two mirrors. They then sent a laser through the optical cavity, where it ping-ponged between the mirrors, interacting with the atoms thousands of times.

"It's like the light serves as a communication link between atoms," Shu explains. "The first atom that sees this light will modify the light slightly, and that light also modifies the second atom, and the third atom, and through many cycles, the atoms collectively know each other and start behaving similarly."

In this way, the researchers quantumly entangle the atoms, and then use another laser, similar to existing atomic clocks, to measure their average frequency. When the team ran a similar experiment without entangling atoms, they found that the atomic clock with entangled atoms reached a desired precision four times faster.

"You can always make the clock more accurate by measuring longer," Vuletic says. "The question is, how long do you need to reach a certain precision. Many phenomena need to be measured on fast timescales."

He says if today's state-of-the-art atomic clocks can be adapted to measure quantumly entangled atoms, they would not only keep better time, but they could help decipher signals in the universe such as dark matter and gravitational waves, and start to answer some age-old questions.

Read more at Science Daily

Device mimics life's first steps in outer space

 A device developed by scientists at the CY Cergy Paris University and Paris Observatory promises insight into how the building blocks of life form in outer space.

In an article published in Review of Scientific Instruments, by AIP Publishing, the scientists detail how VENUS -- an acronym of the French phrase "Vers de Nouvelles Syntheses," which means "toward new syntheses" -- mimics how molecules come together in the freezing darkness of interstellar space.

"We try to simulate how complex organic molecules are formed in such a harsh environment," said Emanuele Congiu, one of the authors and an astrophysicist at the observatory. "Observatories can see a lot of molecules in space. What we do not understand yet, or fully, is how they formed in this harsh environment."

VENUS has a chamber designed to replicate the strong vacuum of space, while holding a frigid temperature that is set lower than minus 400 degrees Fahrenheit (10 kelvins). It uses up to five beams to deliver atoms or molecules onto a tiny sliver of ice without disturbing that environment.

That process, Congiu said, replicates how molecules form on the ice that sits atop tiny dust particles found inside interstellar clouds. VENUS is the first device to do the replication with more than three beams, which lets researchers simulate more complicated interactions.

Over the past 50 years, nearly 200 different molecular species have been discovered in the star-forming regions of space. Some of them, the so-called "prebiotic species," are believed by scientists to be involved in the processes that lead to the early forms of life.

A key use of the VENUS device will be working in concert with scientists who discover molecular reactions in space but need a fuller understanding of what they have observed. It specifically mentions NASA's launch of the James Webb Space Telescope, which is scheduled for 2021. The largest and most powerful space telescope ever launched, it is expected to dramatically expand scientists' knowledge of the universe.

"What we can do in the lab in one day takes thousands of years in space," Congiu said. "Our work in the lab can complement the wealth of data that comes from the space observatories. Otherwise, astronomers would not be able to interpret all of their observations. Researchers who make observations can ask us to simulate a certain reaction, to see if what they think they see is real or not."

From Science Daily

A pair of lonely planet-like objects born like stars

 Star-forming processes sometimes create mysterious astronomical objects called brown dwarfs, which are smaller and colder than stars, and can have masses and temperatures down to those of exoplanets in the most extreme cases. Just like stars, brown dwarfs often wander alone through space, but can also be seen in binary systems, where two brown dwarfs orbit one another and travel together in the galaxy.

Researchers led by Clémence Fontanive from the Center for Space and Habitability (CSH) and the NCCR PlanetS discovered a curious starless binary system of brown dwarfs. The system CFHTWIR-Oph 98 (or Oph 98 for short) consists of the two very low-mass objects Oph 98 A and Oph 98 B. It is located 450 light years away from Earth in the stellar association Ophiuchus. The researchers were surprised by the fact that Oph 98 A and B are orbiting each other from a strikingly large distance, about 5 times the distance between Pluto and the Sun, which corresponds to 200 times the distance between the Earth and the Sun. The study has just been published in The Astrophysical Journal Letters.

Extremely low masses and a very large separation

The pair is a rare example of two objects similar in many aspects to extra-solar giant planets, orbiting around each other with no parent star. The more massive component, Oph 98 A, is a young brown dwarf with a mass of 15 times that of Jupiter, which is almost exactly on the boundary separating brown dwarfs from planets. Its companion, Oph 98 B, is only 8 times heavier than Jupiter.

Components of binary systems are tied by an invisible link called gravitational binding energy, and this bond gets stronger when objects are more massive or closer to one another. With extremely low masses and a very large separation, Oph 98 has the weakest binding energy of any binary system known to date.

Discovery thanks to data from Hubble

Clémence Fontanive and her colleagues discovered the companion to Oph 98 A using images from the Hubble Space Telescope. Fontanive says: "Low-mass brown dwarfs are very cold and emit very little light, only through infrared thermal radiation. This heat glow is extremely faint and red, and brown dwarfs are hence only visible in infrared light." Furthermore, the stellar association in which the binary is located, Ophiuchus, is embedded in a dense, dusty cloud which scatters visible light. "Infrared observations are the only way to see through this dust," explains the lead researcher. "Detecting a system like Oph 98 also requires a camera with a very high resolution, as the angle separating Oph 98 A and B is a thousand times smaller than the size of the moon in the sky," she adds. The Hubble Space Telescope is among the few telescopes capable of observing objects as faint as these brown dwarfs, and able to resolve such tight angles.

Because brown dwarfs are cold enough, water vapor forms in their atmospheres, creating prominent features in the infrared that are commonly used to identify brown dwarfs. However, these water signatures cannot be easily detected from the surface of the Earth. Located above the atmosphere in the vacuum of space, Hubble allows to probe the existence of water vapor in astronomical objects. Fontanive explains: "Both objects looked very red and showed clear signs of water molecules. This immediately confirmed that the faint source we saw next to Oph 98 A was very likely to also be a cold brown dwarf, rather than a random star that happened to be aligned with the brown dwarf in the sky."

The team also found images in which the binary was visible, collected 14 years ago with the Canada-France-Hawaii Telescope (CFHT) in Hawaii. "We observed the system again this summer from another Hawaiian observatory, the United Kingdom Infra-Red Telescope. Using these data, we were able to confirm that Oph 98 A and B are moving together across the sky over time, relative to other stars located behind them, which is evidence that they are bound to each other in a binary pair," explains Fontanive.

An atypical result of star formation

The Oph 98 binary system formed only 3 million years ago in the nearby Ophiuchus stellar nursery, making it a newborn on astronomical timescales. The age of the system is much shorter than the typical time needed to build planets. Brown dwarfs like Oph 98 A are formed by the same mechanisms as stars. Despite Oph 98 B being the right size for a planet, the host Oph 98 A is too small to have a sufficiently large reservoir of material to build a planet that big. "This tells us that Oph 98 B, like its host, must have formed through the same mechanisms that produce stars and shows that the processes that create binary stars operate on scale-down versions all the way down to these planetary masses," comments Clémence Fontanive.

With the discovery of two planet-like worlds -- already uncommon products of star formation -- bound to each other in such an extreme configuration, "we are really witnessing an incredibly rare output of stellar formation processes," as Fontanive describes.

Bernese space exploration: With the world's elite since the first moon landing

When the second man, "Buzz" Aldrin, stepped out of the lunar module on July 21, 1969, the first task he did was to set up the Bernese Solar Wind Composition experiment (SWC) also known as the "solar wind sail" by planting it in the ground of the moon, even before the American flag. This experiment, which was planned and the results analysed by Prof. Dr. Johannes Geiss and his team from the Physics Institute of the University of Bern, was the first great highlight in the history of Bernese space exploration.

Read more at Science Daily

The DNA regions in our brain that contribute to make us human

 With only 1% difference, the human and chimpanzee protein-coding genomes are remarkably similar. Understanding the biological features that make us human is part of a fascinating and intensely debated line of research. Researchers at the SIB Swiss Institute of Bioinformatics and the University of Lausanne have developed a new approach to pinpoint, for the first time, adaptive human-specific changes in the way genes are regulated in the brain. These results open new perspectives in the study of human evolution, developmental biology and neurosciences. The paper is published in Science Advances.

Gene expression, not gene sequence

To explain what sets human apart from their ape relatives, researchers have long hypothesized that it is not so much the DNA sequence, but rather the regulation of the genes (i.e. when, where and how strongly the gene is expressed), that plays the key role. However, precisely pinpointing the regulatory elements which act as 'gene dimmers' and are positively selected is a challenging task that has thus far defeated researchers (see box).

Marc Robinson-Rechavi, Group Leader at SIB and study co-author says: "To be able to answer such tantalizing questions, one has to be able identify the parts in the genome that have been under so called 'positive' selection [see box]. The answer is of great interest in addressing evolutionary questions, but also, ultimately, could help biomedical research as it offers a mechanistic view of how genes function."

A high proportion of the regulatory elements in the human brain have been positively selected

Researchers at SIB and the University of Lausanne have developed a new method which has enabled them to identify a large set of gene regulatory regions in the brain, selected throughout human evolution. Jialin Liu, Postdoctoral researcher and lead author of the study explains: "We show for the first time that the human brain has experienced a particularly high level of positive selection, as compared to the stomach or heart for instance. This is exciting, because we now have a way to identify genomic regions that might have contributed to the evolution of our cognitive abilities!"

To reach their conclusions, the two researchers combined machine learning models with experimental data on how strongly proteins involved in gene regulation bind to their regulatory sequences in different tissues, and then performed evolutionary comparisons between human, chimpanzee and gorilla. "We now know which are the positively selected regions controlling gene expression in the human brain. And the more we learn about the genes they are controlling, the more complete our understanding of cognition and evolution, and the more scope there will be to act on that understanding," concludes Marc Robinson-Rechavi.

Read more at Science Daily

The human helpers of SARS-CoV-2

 Like all viruses, the novel coronavirus is dependent on help from the human host cell. Proteins are the functional units of the cell and enable the virus to enter the host cell or help the virus to replicate. Scientists from Charité -- Universitätsmedizin Berlin and from the Berlin Institute of Health (BIH), along with colleagues from the United Kingdom, Germany and the United States, have examined the corresponding genes of the helper proteins in a large study. They discovered numerous variants that influence the amount or function of the proteins as well as their ability to support the virus. The gene variants reveal potential target structures for new drugs. The researchers have now published their results in the journal Nature Communications.

An infection of the novel coronavirus SARS-CoV-2, just like any other viral infection, follows a specific pattern: The viruses first bind to receptor proteins on the surface of the human host cells in the throat, nose or lungs before entering the cell, where they replicate with the help of the host cell machinery. The newly formed virus particles cause the infected cell to burst and infect other cells. As soon as the immune system notices what is happening, a defense mechanism is activated with the goal of destroying and removing both the viruses and virus-infected cells. Under normal circumstances, the infection is over within two weeks at the most. For all these processes, however, the virus is dependent on human or host proteins.

"In severe courses of COVID-19, this regulated process gets out of control and the immune system causes an excessive inflammatory response that attacks not only virus-infected cells but also healthy tissue," says Prof. Dr. Claudia Langenberg, BIH Professor of Computational Medicine and head of the study now being published. "Naturally occurring variations in the genes that make up the blueprint for these human proteins can alter their concentration or function and may thus be responsible for the different course of the disease." The team is well versed in the discovery of genetic variants that not only affect specific proteins but also common complex diseases. "As molecular epidemiologists, we study the diversity of genes -- that is, the building instructions for proteins -- of entire population groups in order to uncover susceptibilities to diseases whose cause lies in the interaction of many small deviations," explains the epidemiologist, who joined the BIH from the Medical Research Council Epidemiology Unit at the University of Cambridge in September. "We wanted to use these experiences and data sets for the COVID-19 epidemic and make them available to the scientific community."

"We examined 179 proteins known to be involved in SARS-CoV-2 infection for their naturally occurring variants," reports Dr. Maik Pietzner, the study's lead author and a scientist in Prof. Langenberg's lab. "We were able to draw on findings which were based on samples of the first COVID-19 patients at Charité. " This was possible due to close collaboration with the research group led by Professor Dr. Markus Ralser, Director of the Institute of Biochemistry at Charité, which had previously reported these findings. The team of Prof. Langenberg was able to use data from the MRC Fenland Cohort, a large population study that contains information from more than 10,000 individuals. They discovered 38 targets for existing drugs as well as evidence that certain proteins that interact with the virus influence the immune system. "Our findings also help to better understand risk factors for severe courses of COVID-19. We were able to show that blood coagulation proteins are influenced by the same genetic variant that increases the risk of contracting COVID-19 and that determines blood group 0," reports Dr. Pietzner.

Read more at Science Daily

Astronomers detect possible radio emission from exoplanet

 

Illustration of a 'hot Jupiter' exoplanet orbiting nearby star.

By monitoring the cosmos with a radio telescope array, an international team of scientists has detected radio bursts emanating from the constellation Boötes -- that could be the first radio emission collected from a planet beyond our solar system.

The team, led by Cornell postdoctoral researcher Jake D. Turner, Philippe Zarka of the Observatoire de Paris -- Paris Sciences et Lettres University and Jean-Mathias Griessmeier of the Université d'Orléans will publish their findings in the forthcoming research section of Astronomy & Astrophysics, on Dec. 16.

"We present one of the first hints of detecting an exoplanet in the radio realm," Turner said. "The signal is from the Tau Boötes system, which contains a binary star and an exoplanet. We make the case for an emission by the planet itself. From the strength and polarization of the radio signal and the planet's magnetic field, it is compatible with theoretical predictions."

Among the co-authors is Turner's postdoctoral advisor Ray Jayawardhana, the Harold Tanner Dean of the College of Arts and Sciences, and a professor of astronomy.

"If confirmed through follow-up observations," Jayawardhana said, "this radio detection opens up a new window on exoplanets, giving us a novel way to examine alien worlds that are tens of light-years away."

Using the Low Frequency Array (LOFAR), a radio telescope in the Netherlands, Turner and his colleagues uncovered emission bursts from a star-system hosting a so-called hot Jupiter, a gaseous giant planet that is very close to its own sun. The group also observed other potential exoplanetary radio-emission candidates in the 55 Cancri (in the constellation Cancer) and Upsilon Andromedae systems. Only the Tau Boötes exoplanet system -- about 51 light-years away -- exhibited a significant radio signature, a unique potential window on the planet's magnetic field.

Observing an exoplanet's magnetic field helps astronomers decipher a planet's interior and atmospheric properties, as well as the physics of star-planet interactions, said Turner, a member of Cornell's Carl Sagan Institute.

Earth's magnetic field protects it from solar wind dangers, keeping the planet habitable. "The magnetic field of Earth-like exoplanets may contribute to their possible habitability," Turner said, "by shielding their own atmospheres from solar wind and cosmic rays, and protecting the planet from atmospheric loss."

Two years ago, Turner and his colleagues examined the radio emission signature of Jupiter and scaled those emissions to mimic the possible signatures from a distant Jupiter-like exoplanet. Those results became the template for searching radio emission from exoplanets 40 to 100 light-years away.

After poring over nearly 100-hours of radio observations, the researchers were able to find the expected hot Jupiter signature in Tau Boötes. "We learned from our own Jupiter what this kind of detection looks like. We went searching for it and we found it," Turner said.

The signature, though, is weak. "There remains some uncertainty that the detected radio signal is from the planet. The need for follow-up observations is critical," he said.

Turner and his team have already begun a campaign using multiple radio telescopes to follow up on the signal from Tau Boötes.

Read more at Science Daily

The farthest galaxy in the universe

 A team of astronomers used the Keck I telescope to measure the distance to an ancient galaxy. They deduced the target galaxy GN-z11 is not only the oldest galaxy but also the most distant. It's so distant it defines the very boundary of the observable universe itself. The team hopes this study can shed light on a period of cosmological history when the universe was only a few hundred million years old.

We've all asked ourselves the big questions at times: "How big is the universe?" or "How and when did galaxies form?" Astronomers take these questions very seriously, and use fantastic tools that push the boundaries of technology to try and answer them. Professor Nobunari Kashikawa from the Department of Astronomy at the University of Tokyo is driven by his curiosity about galaxies. In particular, he sought the most distant one we can observe in order to find out how and when it came to be.

"From previous studies, the galaxy GN-z11 seems to be the farthest detectable galaxy from us, at 13.4 billion light years, or 134 nonillion kilometers (that's 134 followed by 30 zeros)," said Kashikawa. "But measuring and verifying such a distance is not an easy task."

Kashikawa and his team measured what's known as the redshift of GN-z11; this refers to the way light stretches out, becomes redder, the farther it travels. Certain chemical signatures, called emission lines, imprint distinct patterns in the light from distant objects. By measuring how stretched these telltale signatures are, astronomers can deduce how far the light must have traveled, thus giving away the distance from the target galaxy.

"We looked at ultraviolet light specifically, as that is the area of the electromagnetic spectrum we expected to find the redshifted chemical signatures," said Kashikawa. "The Hubble Space Telescope detected the signature multiple times in the spectrum of GN-z11. However, even the Hubble cannot resolve ultraviolet emission lines to the degree we needed. So we turned to a more up-to-date ground-based spectrograph, an instrument to measure emission lines, called MOSFIRE, which is mounted to the Keck I telescope in Hawaii."

The MOSFIRE captured the emission lines from GN-z11 in detail, which allowed the team to make a much better estimation on its distance than was possible from previous data. When working with distances at these scales, it is not sensible to use our familiar units of kilometers or even multiples of them; instead, astronomers use a value known as the redshift number denoted by z. Kashikawa and his team improved the accuracy of the galaxy's z value by a factor of 100. If subsequent observations can confirm this, then the astronomers can confidently say GN-z11 is the farthest galaxy ever detected in the universe.

From Science Daily