Daily Archives: 2 Mar 2021

Planetary Science

Three Elder Sisters of the Sun With Planets (Planetary Science)

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An international team led by Prof. dr habil. Andrzej Niedzielski, an astronomer from the Nicolaus Copernicus University in Toruń, has discovered yet another three extrasolar planets. These planets revolve around the stars that can be called elder sisters of our Sun.

You can read about the astronomers’ success in “Astronomy and Astrophysics”. The prestigious European journal will publish the paper: “Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. VII. Elder suns with low-mass companions”. Apart from Prof. Andrzej Niedzielski from the NCU Institute of Astronomy, the team which worked on the discovery includes Prof. dr habil. Gracjan Maciejewski, also from the NCU Faculty of Physics, Astronomy and Informatics, Prof. Aleksander Wolszczan (Pennsylvania State University), dr Eva Villaver (University of Madrid) as well as dr Monika Adamów and dr Kacper Kowalik (both from the University of Illinois).

Discoverers of planets

Prof. Niedzielski’s team have been working on this subject for years. Thanks to precise observations of the sky, they have managed to discover 26 stars around which planets revolve. These are usually planetary systems much older than ours. Their suns are mostly red giants. An exception is the Solaris system and the Pirx, a star similar to the Sun (although slightly less massive and cooler) and its planet, discovered in 2009.

– The red giant is a star that has burnt out hydrogen in its interior as a result of nuclear reactions and is rebuilding its internal structure to ignite helium burning nuclear reactions – explains Prof. Niedzielski, – Such a star shrinks in its central part, where the temperature starts to rise. Its outer areas expand significantly and cool down.  Initially a yellow star, like the Sun, becomes red and huge. Hence the name of this type of stars. These stars can reach a size comparable to that of Earth’s orbit.

Sisters of the Sun

The astronomers looked at 122 stars. They carried out their observations using the Hobby-Eberly Telescope (HET) at the McDonald Observatory, near Fort Davis, Texas, and the Italian National Galileo Telescope, which is located on the island of La Palma (Canary Islands) in Spain. They succeeded in discovering other extrasolar planets orbiting the stars which could be called the big sisters of our Sun.

Artist’s animation of the Sun becoming a red giant (Credit: ESA/Hubble, M. Kornmesser & L. L. Christensen):

– These stars are red giants. They have masses exactly the same as our star, but they are a few billion years older, much bigger and cooler – explains Prof. Niedzielski, – The planets that we have discovered are gas giants – without surfaces, similar to our Jupiter. They orbit far too close to their stars for conditions favourable for the origin of life to occur on them or in their vicinity

Eldest sister: HD 4760

The star HD 4760 is an eighth magnitude object in Pisces constellation. It is 40 times larger and emits 850 times more light than the Sun, but because of its distance (about 1781 light years away from us) it is invisible to the naked eye, but it is already within reach of even small and amateur telescopes.

“A planet about 14 times more massive than Jupiter revolves around it. It is in an orbit similar in size to that of Earth around the Sun, at a distance of about 1.1 astronomical units. A year on this planet lasts 434 days”

— says Prof. Niedzielski.

The observations of the star that led to the discovery of the planet took 9 years. They were conducted first with the Hobby-Eberly telescope and the HRS spectrograph, then with the Galileo telescope and the Harps-N.

– The observations were so long because in the case of the search for planets near red giants it is necessary to study several periods of rotation of the star, which can reach hundreds of days – explains the astronomer from Toruń, – The researchers must make sure that a planet is actually observed, and not a spot on the star’s surface that pretends to be a planet.

Younger sisters: TYC 0434-04538-1 and HD 96992

The astronomers have recently discovered a planet orbiting the TYC 0434-04538-1, a star about 2032 light-years away from us, in the Serpens constellation. Although it shines almost 50 times more strongly than the Sun, it is also invisible to the naked eye. The reason is again the great distance – to see this object of tenth apparent magnitude, you already need a small telescope. This star is ten times bigger than the Sun, and it is surrounded by a planet six times more massive than Jupiter.

“Interestingly, this planet orbits quite close to its star, at a distance of 0.66 astronomical units. In our Solar System it would be located between the orbits of Venus and Earth – explains Prof. Niedzielski, – A year on this gas planet lasts only 193 days.“

Observations of this star with both telescopes lasted 10 years.

The third of the Sun’s elder sisters, the HD 96992, is closest to us – “only” 1305 light years away. It is a star of the ninth magnitude in the Great Bear.

“This star, seven times bigger and almost 30 times more energetic than the Sun, has a planet with a mass only slightly bigger than that of Jupiter, in an orbit of 1.24 astronomical units. A year on this planet lasts 514 days.”

— says Prof. Niedzielski.

This star has been observed with the use of two telescopes by astronomers for the longest time – 14 years.

*NASA (National Advisory Committee for Aeronautics): exoplanetary encyclopedia combines interactive visualizations with detailed data on all known exoplanets. Click on a planet’s name to see 3D model of each planet and system along with vital statistics:  HD 4760, TYC 0434-04538-1, HD 96992

Dictionary

Apparent magnitude is a conventional unit of star brightness introduced by Ptolemy in the 2nd century AD. The brightest stars are objects of the first magnitude, the faintest visible to the naked eye are of the sixth magnitude. Polaris, for example, is the object of second magnitude.

The astronomical unit (a.u.) is a conventional measure of distance used in astronomy, the average distance between Earth and the Sun. It is 149 597 870.7 km. The Moon is 0.026 a.u. away from Earth and Jupiter is 5.2 a.u. away from the Sun. The astronomical unit is often used to describe planetary systems. 

The light year is the distance that light travels in vacuum during one year. It is another conventional measure of (large) distances in astronomy. It is 9.5 trillion km (63,241 AU). This unit is often used to characterise the distances of stars in the Galaxy. The Moon is at a distance of 1.3 light seconds away from Earth. The nearest star, Proxima Centauri – 4.22 light years away.

Jupiter mass is the conventional unit of mass readily used to describe planets. It is approximately 1.9 1027 kg. The mass of Jupiter is 318 times greater than the mass of Earth. For comparison, the mass of the Sun is 1047 Jupiter masses.

Featured image: Prof. Niedzielski’s team have been working on this subject for years. Thanks to precise observations of the sky, they have managed to discover 26 stars around which planets revolve © Andrzej Romański

Reference: A.T. Niedzielski, E. Villaver, M. Adamow, K. Kowalik, A. Wolszczan, G. Maciejewski, “Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. VII. Elder suns with low-mass companions”, A&A, 2021. DOI https://doi.org/10.1051/0004-6361/202037892

Provided by NCU in Torun

Medicine

Skipping Mammogram Increases Risk of Death From Breast Cancer (Medicine)

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Consecutive mammography can lower risk of mortality within 10 years of diagnosis

Attendance at regular mammography screening substantially reduces the risk of dying from breast cancer, according to a large study of over half a million women, published in Radiology. Researchers said women who skip even one scheduled mammography screening before a breast cancer diagnosis face a significantly higher risk of dying from the cancer.

Breast cancer screening with mammography has helped reduce disease-related deaths by enabling detection of cancer at earlier, more treatable stages. Despite mammography’s well-established effectiveness, many women don’t participate in recommended screening examinations.

Duffy © RSNA

In the new study, led by László Tabár, M.D., from Falun Central Hospital in Falun, Sweden, and funded by the American Cancer Society, a multinational team of researchers took a more detailed look at screening attendance patterns to further refine mortality risk estimates. They analyzed data from almost 550,000 women eligible for mammography screening in nine Swedish counties between 1992 and 2016. The women were divided into groups based on their participation in the two most recent scheduled screening exams prior to cancer diagnosis. Women who participated in both screening sessions prior to diagnosis were identified as serial participants, while those who did not attend either screening opportunity were categorized as serial nonparticipants.

Analysis showed that participation in the two most recent mammography screening appointments before a breast cancer diagnosis provides a higher protection against breast cancer death than participation in neither or only one examination.

The incidence of breast cancers proving fatal within 10 years of diagnosis was 50% lower for serial participants than for serial nonparticipants. Compared to women who attended only one of the two previous screens, women who attended both had a 29% reduction in breast cancer mortality.

“Regular participation in all scheduled screens confers the greatest reduction in your risk of dying from breast cancer,” said the study’s lead author, Stephen W. Duffy, M.Sc., professor of cancer screening at Queen Mary University of London.

Duffy said the results add further evidence to support regular screening with mammography as a means for reducing breast cancer-related deaths.

“While we suspected that regular participation would confer a reduction greater than that with irregular participation, I think it is fair to say that we were slightly surprised by the size of the effect,” Duffy said. “The findings support the hypothesis that regular attendance reduces the opportunity for the cancer to grow before it is detected.”

The researchers are continuing to study mammography data to develop a more comprehensive picture of screening benefits, including the impact on interval cancers that arise between screening mammography examinations.

“We are planning further prognostic research into the mechanism of this effect,” Duffy said. “For example, we plan to investigate whether and–if so–to what extent regular attendance improves the prognosis of interval cancers as well as screen-detected cancers. Estimation of this by time since last screen may have implications for policy on screening frequency.”

For More Information

Access the Radiology study, “Beneficial Effect of Consecutive Mammography Screening Examinations on Mortality from Breast Cancer: A Prospective Study.”

Provided by RSNA

Biology

Groundbreaking Research into White-Rot Fungi Proves Its Value in Carbon Sequestration from Lignin (Biology)

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A foundational study conducted by scientists at the National Renewable Energy Laboratory (NREL) shows for the first time that white-rot fungi are able to use carbon captured from lignin as a carbon source.

The research confirms a hypothesis from Davinia Salvachúa Rodriguez, the senior author of a newly published paper. Until now, scientists were unsure whether white-rot fungi—the most efficient lignin-degrading organisms in nature—actually consume the products generated from breaking down lignin.

“What we have demonstrated here is that white-rot fungi can actually utilize lignin-derived aromatic compounds as a carbon source, which means they can eat them and utilize them to grow,” Salvachúa said. “That is another strategy for carbon sequestration in nature and has not been reported before.”

The paper, “Intracellular pathways for lignin catabolism in white-rot fungi,” appears in the journal Proceedings of the National Academy of Sciences. Her co-authors from NREL are Carlos del Cerro, Erika Erickson, Tao Dong, Kelsey Ramirez, Venkataramanan Subramanian, Rui Katahira, Jeffrey Linger, Wei Xiong, and Michael Himmel. Other co-authors are from the Environmental Molecular Sciences Laboratory at Pacific Northwest National Laboratory and the Joint Genome Institute at Lawrence Berkeley National Laboratory.

Salvachúa, a research scientist in NREL’s Renewable Resources and Enabling Sciences Center, has spent more than a decade studying white-rot fungi. Last year, the Department of Energy’s Office of Science awarded her a prestigious $2.5 million grant as part of the Early Career Research Program to further her work.

White-rot fungi evolved to degrade lignin, which Salvachúa calls “the most recalcitrant biopolymer on Earth.” Lignin helps make the plant’s cell walls more rigid. Other parts of the plant, such as cellulose, are also recalcitrant but can be fully depolymerized to single monomeric species for use as a biofuel and biochemical precursors, for example. But the intractability of lignin and the lack of an efficient method to deconstruct and convert lignin to monomeric compounds hampers the viability of plant-based biorefineries.

Salvachúa’s work forms the foundation of a new research area based on lignin being broken down by white-rot fungi, which could be further exploited to simultaneously convert the biopolymer into value-added compounds.

The researchers examined two species of white-rot fungi: Trametes versicolor and Gelatoporia subvermispora. Through the use of genomic analysis, isotopic labeling, and systems biology approaches, the researchers determined the ability of these organisms to incorporate carbon from lignin-derived aromatic compounds into central metabolism and were able to map out the potential aromatic catabolic pathways for that conversion process. Further, in vitro enzyme analyses enable validation of some of the proposed steps. The researchers also highlight that this work is just the beginning of a broad area towards discovering new enzymes and pathways and better understanding carbon flux in these organisms.

Lignin accounts for about 30% of the organic carbon in the biosphere. Concerns about the changing climate have sparked a growing interest in the issue of carbon cycling, in which carbon is absorbed by natural reservoirs—such as plants—from the atmosphere and later decomposed and returned to the atmosphere or other natural reservoirs. Because more carbon is stored in the soil than in the atmosphere or plants, white-rot fungi are now positioned as key players in the sequestration of lignin-derived carbon in soils.

Scientists have demonstrated the ability of some bacterial strains to break down lignin as well, but not as effectively as white-rot fungi. Salvachúa said bacteria are easier to work with than fungi because they grow more quickly, and many are genetically tractable, contrary to white-rot fungi. “With fungi, one experiment can be up to two months,” she said. “We try to be very careful when we plan an experiment because that’s a long time. That’s six experiments a year if you need results to move forward. With bacteria, you can do one per week.”

The Department of Energy’s Office of Science, Biological and Environmental Research program, funded a portion of the research, with other funding coming from the Laboratory Directed Research and Development program at NREL.

NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by the Alliance for Sustainable Energy, LLC.

Featured image: Davinia Salvachúa Rodriguez holds a petri dish containing white-rot fungi. She is the senior author of a study showing that white-rot fungi consume and use the products generated from breaking down lignin, a pathway for sequestering carbon in nature. Photo by Werner Slocum, NREL

Reference: Carlos del Cerro, Erika Erickson, Tao Dong, Allison R. Wong, Elizabeth K. Eder, Samuel O. Purvine, Hugh D. Mitchell, Karl K. Weitz, Lye Meng Markillie, Meagan C. Burnet, David W. Hoyt, Rosalie K. Chu, Jan-Fang Cheng, Kelsey J. Ramirez, Rui Katahira, Wei Xiong, Michael E. Himmel, Venkataramanan Subramanian, Jeffrey G. Linger, Davinia Salvachúa, “Intracellular pathways for lignin catabolism in white-rot fungi”, Proceedings of the National Academy of Sciences Mar 2021, 118 (9) e2017381118; DOI: 10.1073/pnas.2017381118

Provided by NREL

Planetary Science

Space Hurricane Observed For The First Time (Planetary Science)

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The first observations of a space hurricane have been revealed in Earth’s upper atmosphere, confirming their existence and shedding new light on the relationship between planets and space.

The unprecedented observations, made by satellites in August 2014, were only uncovered during retrospective analysis by scientists at the University of Reading, as part of a team led by Shandong University in China, that confirmed the hurricane and offered clues about its formation.

This analysis has now allowed a 3D image to be created of the 1,000km-wide swirling mass of plasma several hundred kilometres above the North Pole, raining electrons instead of water, and in many ways resembling the hurricanes we are familiar with in the Earth’s lower atmosphere.

Professor Mike Lockwood, space scientist at the University of Reading, said: “Until now, it was uncertain that space plasma hurricanes even existed, so to prove this with such a striking observation is incredible”.

“Tropical storms are associated with huge amounts of energy, and these space hurricanes must be created by unusually large and rapid transfer of solar wind energy and charged particles into the Earth’s upper atmosphere.

“Plasma and magnetic fields in the atmosphere of planets exist throughout the universe, so the findings suggest space hurricanes should be a widespread phenomena.”

Hurricanes occur in Earth’s lower atmosphere over warm bodies of water. When warm, moist air rises, it creates an area of low pressure near the surface that sucks in the surrounding air, causing extremely strong winds and creating clouds that lead to heavy rain.

Hurricanes have also been observed in the lower atmospheres of Mars, Jupiter and Saturn, while enormous solar tornadoes have been seen in the atmosphere of the Sun. However, the existence of space hurricanes in the upper atmosphere of planets has not been detected before.

The space hurricane analysed by the team in Earth’s ionosphere was spinning in an anticlockwise direction, had multiple spiral arms, and lasted almost eight hours before gradually breaking down.

The team of scientists from China, the USA, Norway and the UK used observations made by four DMSP (Defense Meteorological Satellite Program) satellites and a 3D magnetosphere modelling to produce the image. Their findings were published in Nature Communications.

The analysis involved checking data from the satellites, radars and other sources for consistency, and to build up a full picture of what had happened and ensure that the mechanisms involved were understood.

The fact the hurricane occurred during a period of low geomagnetic activity suggests they could be more relatively common within our solar system and beyond. This highlights the importance of improved monitoring of space weather, which can disrupt GPS systems.

Featured image: Illustration of a space hurricane, created using the observation data. Credit Qing-He Zhang, Shandong University

Reference: Zhang, QH., Zhang, YL., Wang, C., Oksavik, K., Lyons, L., Lockwood, M., Yang, HG., Tang, BB., Moen, J., Wing, ZY., Ma, YZ., Wang, XY., Ning, YF., Xia, LD. (2021). ‘A space hurricane over the Earth’s polar ionosphere’. Nat Communications 12, 1207 (2021). Doi: 10.1038/s41467-021-21459-y

Provided by University of Reading

Planetary Science

Astrophysicist’s 2004 Theory Confirmed: Why the Sun’s Composition Varies (Planetary Science)

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About 17 years ago, J. Martin Laming, an astrophysicist at the U.S. Naval Research Laboratory, theorized why the chemical composition of the Sun’s tenuous outermost layer differs from that lower down. His theory has recently been validated by combined observations of the Sun’s magnetic waves from the Earth and from space. 

His most recent scientific journal article describes how these magnetic waves modify chemical composition in a process completely new to solar physics or astrophysics, but already known in optical sciences, having been the subject of Nobel Prizes awarded to Steven Chu in 1997 and Arthur Ashkin in 2018.

Laming began exploring these phenomena in the mid-1990s, and first published the theory in 2004.

“It’s satisfying to learn that the new observations demonstrate what happens “under the hood” in the theory, and that it actually happens for real on the Sun,” he said.

The Sun is made up of many layers. Astronomers call its outermost layer the solar corona, which is only visible from earth during a total solar eclipse. All solar activity in the corona is driven by the solar magnetic field. This activity consists of solar flares, coronal mass ejections, high-speed solar wind, and solar energetic particles. These various manifestations of solar activity are all propagated or triggered by oscillations or waves on the magnetic field lines.

“The very same waves, when they hit the lower solar regions, cause the change in chemical composition, which we see in the corona as this material moves upwards,” Laming said. “In this way, the coronal chemical composition offers a new way to understand waves in the solar atmosphere, and new insights into the origins of solar activity.”

Christoph Englert, head of the U.S. Naval Research Laboratory’s Space Science Division, points out the benefits for predicting the Sun’s weather and how Laming’s theory could help predict changes in our ability to communicate on Earth.

“We estimate that the Sun is 91 percent hydrogen but the small fraction accounted for by minor ions like iron, silicon, or magnesium dominates the radiative output in ultraviolet and X-rays from the corona,” he said. “If the abundance of these ions is changing, the radiative output changes.”

“What happens on the Sun has significant effects on the Earth’s upper atmosphere, which is important for communication and radar technologies that rely on over-the-horizon or ground-to-space radio frequency propagation,” Englert said.

It also has an impact on objects in orbit. The radiation is absorbed in the Earth’s upper atmospheric layers, which causes the upper atmosphere to form plasma, the ionosphere, and to expand and contract, influencing the atmospheric drag on satellites and orbital debris.

“The Sun also releases high energy particles,” Laming said. “They can cause damage to satellites and other space objects. The high energy particles themselves are microscopic, but it’s their speed that causes them to be dangerous to electronics, solar panels, and navigation equipment in space.”

Englert said that reliably forecasting solar activity is a long-term goal, which requires us to understand the inner workings of our star. This latest achievement is a step in this direction. 

“There is a long history of advances in astronomy seeding technological progress, going all the way back to Galileo,” Englert said. “We are excited to carry on this tradition in support of the U.S. Navy.”

The Space Science Division executes research, development, tests and evaluations in solar-terrestrial physics, astrophysics, upper/middle atmospheric science, and astronomy. These include instruments to be flown on satellites, sounding rockets and balloons, and ground-based facilities and mathematical models.

Featured image: The solar corona viewed in white light during the total solar eclipse on Aug. 21, 2017 from Mitchell, Oregon. The moon blocks out the central part of the Sun, allowing the tenuous outer regions to be seen in full detail. The image is courtesy of Benjamin Boe and first published in “CME-induced Thermodynamic Changes in the Corona as Inferred from Fe XI and Fe XIV Emission Observations during the 2017 August 21 Total Solar Eclipse”, Boe, Habbal, Druckmüller, Ding, Hodérova, & Štarha, Astrophysical Journal, 888, 100, (Jan. 10, 2020). (Photo by AAS)

Reference: J. Martin Laming, “The FIP and Inverse FIP Effects in Solar Flares”, ArXiv, pp. 1-13, 2021. https://arxiv.org/abs/2101.03038

Provided by US Naval Research Laboratory

About the U.S. Naval Research Laboratory 

NRL is a scientific and engineering command dedicated to research that drives innovative advances for the U.S. Navy and Marine Corps from the seafloor to space and in the information domain. NRL is located in Washington, D.C. with major field sites in Stennis Space Center, Mississippi; Key West, Florida; Monterey, California, and employs approximately 2,500 civilian scientists, engineers and support personnel.

Material science

Soft And Comfortable e-textiles That Can Be Used to Measure Photoplenthysmography (Material Science)

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The performances of fiber optoelectronic components were improved by wrapping electrodes with desired shapes around the thread. Fiber photodiodes were integrated into the fabric to measure the wearer’s pulse from their fingertips

Advances in wearable devices have enabled e-textiles, which fuse lightweight and comfortable textiles with smart electronics, and are garnering attention as the next-generation wearable technology. In particular, fiber electronic devices endowed with electrical properties, while retaining the specific characteristics of textiles, are key elements in manufacturing e-textiles.

Optoelectronic devices are generally constructed using layers of semiconductors, electrodes, and insulators; their performance is greatly affected by the size and structure of the electrodes. Fiber electronic components for e-textiles need to be fabricated on thin, pliable threads; since these devices cannot be wider than threads having diameter of a few micrometers, it is a challenge to improve the performances of such fiber electronic components. However, a team of Korean scientists has been receiving attention after developing a new technology to overcome these limitations.

A team of researchers, led by Dr. Hyunjung Yi and Dr. Jung Ah Lim, at the Post-silicon Semiconductor Institute of the Korea Institute of Science and Technology (KIST) announced that they have developed a technique to manufacture fiber electronic components, such as transistors and photodiodes, with desired electrode structures by wrapping. Specifically, the desired electrode array can be fabricated using an inkjet printer, and an electrode thread coated with a semiconductor surface is rolled on top of these electrodes.

(a) Schematic of the rolling-transfer process of printed CNT microelectrodes. (b) Photographs of spirally wrapped CNT microelectrodes on a bare PU and on a Au microfiber coated with an organic semiconductor. © Korea Institute of Science and Technology(KIST)

In 2019, Dr. Yi and her research team developed a technique to build an electrode array on a given surface by printing carbon nanotube (CNT) ink on a template made of a hydrophilic hydrogel and transferring the CNT ink to the desired surface (Nano Letters 2019, 19, 3684-3691). Once printed on the hydrogel, the CNT electrodes behave in a manner similar to floating on water. Hence, the researchers predicted the possibility of transferring such electrodes intact to the surfaces of fibers by rolling the fibers on the electrodes. In a collaborative study with Dr. Lim and her team, the researchers were able to develop high-performance fiber electronic components without damaging the semiconductor layer or CNT electrodes. The fiber transistors wrapped with CNT electrodes maintained stable performances of at least 80% even with a sharp bend radius of 1.75 mm.

Using the semitransparent property of the CNT electrode, the researchers have also succeeded in developing fiber photodiodes to detect light by wrapping the CNT electrodes around electrode threads coated with a semiconductor that produces current upon absorption of light. The fiber photodiodes can detect a wide range of visible light and have excellent sensitivities that are comparable to those of rigid components. The researchers manufactured a glove from a fabric containing these photodiodes and light-emitting diodes (LEDs). The LEDs produce light, and the photodiodes measure the intensity of the light reflected by the fingers, which changes according to blood flow. Thus, the glove can be used to measure the wearer’s pulse.

Dr. Jung Ah Lim, at the Post-silicon Semiconductor Institute, KIST © Korea Institute of Science and Technology(KIST)

Dr. Lim stated that “The finger glove pulse monitor developed by us could offer an alternative to conventional clip-type pulse monitoring device. It has the advantages of being more approachable for patients because of its comfortable and soft texture and of being able to measure the pulse in real time in any time and place.” Dr. Yi, the co-investigator, stated that “This research provides a new approach to electrode fabrication, which remains an important problem to solve in the development of fiber devices. We expect that these findings would advance the field from improving the performances of fiber optoelectronic components to development of fiber electronic devices with complex circuits.”

This research was conducted with support from the Ministry of Science and ICT (MSIT) as part of a major KIST research program and as a part of the National Research Foundation of Korea’s Basic Science Research Program and Nano-Material Technology Development Program for core/follow-up studies. The study has been published in the latest issue of “ACS Nano” an international journal in the field of nanomaterials.

Featured image: Electrodes are transcribed by printing electrodes on hydrogels and rolling fibers over electrodes(Left), Characteristics of modality and actual cardiac measurement applied to phototematic flow measurement at the fingertips by inserting a transcriptional photodiode into the fiber (Right) © Korea Institute of Science and Technology(KIST)

Reference: Hyoungjun Kim, Tae-Hyung Kang, Jongtae Ahn, Hyemi Han, Seongjin Park, Soo Jin Kim, Min-Chul Park, Seung-ho Paik, Do Kyung Hwang, Hyunjung Yi*, and Jung Ah Lim, “Spirally Wrapped Carbon Nanotube Microelectrodes for Fiber Optoelectronic Devices beyond Geometrical Limitations toward Smart Wearable E-Textile Applications”, ACS Nano 2020, 14, 12, 17213–17223.
Publication Date: December 9, 2020
https://doi.org/10.1021/acsnano.0c07143

Provided by National Council Research of Science and Technology

Earth Science

How Much Longer Will the Oxygen-rich Atmosphere be Sustained On Earth? (Earth Science)

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Earth’s surface environments are highly oxygenated – from the atmosphere to the deepest reaches of the oceans, representing a hallmark of active photosynthetic biosphere. However, the fundamental timescale of the oxygen-rich atmosphere on Earth remains uncertain, particularly for the distant future. Solving this question has great ramifications not only for the future of Earth’s biosphere but for the search for life on Earth-like planets beyond the solar system.

A new study published in Nature Geoscience this week tackles this problem using a numerical model of biogeochemistry and climate and reveals that the future lifespan of Earth’s oxygen-rich atmosphere is approximately one billion years.

“For many years, the lifespan of Earth’s biosphere has been discussed based on scientific knowledge about the steadily brightening of the sun and global carbonate-silicate geochemical cycle. One of the corollaries of such a theoretical framework is a continuous decline in atmospheric CO2 levels and global warming on geological timescales. Indeed, it is generally thought that Earth’s biosphere will come to an end in the next 2 billion years due to the combination of overheating and CO2 scarcity for photosynthesis. If true, one can expect that atmospheric O2 levels will also eventually decreases in the distant future. However, it remains unclear exactly when and how this will occur,” says Kazumi Ozaki, Assistant Professor at Toho University.

To examine how Earth’s atmosphere will evolve in the future, Ozaki and Christopher Reinhard, Associate Professor at Georgia Institute of Technology, constructed an Earth system model which simulates climate and biogeochemical processes. Because modelling future Earth evolution intrinsically has uncertainties in geological and biological evolutions, a stochastic approach was adopted, enabling the researchers to obtain a probabilistic assessment of the lifespan of an oxygenated atmosphere. Ozaki ran the model more than 400 thousand times, varying model parameter, and found that Earth’s oxygen-rich atmosphere will probably persist for another one billion years (1.08±0.14 (1σ) billion years) before rapid deoxygenation renders the atmosphere reminiscent of early Earth before the Great Oxidation Event around 2.5 billion years ago.

“The atmosphere after the great deoxygenation is characterized by an elevated methane, low-levels of CO2, and no ozone layer. The Earth system will probably be a world of anaerobic life forms,” says Ozaki.

Earth’s oxygen-rich atmosphere represents an important sign of life that can be remotely detectable. However, this study suggests that Earth’s oxygenated atmosphere would not be a permanent feature, and that the oxygen-rich atmosphere might only be possible for 20-30% of the Earth’s entire history as an inhabited planet. Oxygen (and photochemical byproduct, ozone) is most accepted biosignature for the search for life on the exoplanets, but if we can generalize this insight to Earth-like planets, then scientists need to consider additional biosignatures applicable to weakly-oxygenated and anoxic worlds in the search for life beyond our solar system.

The research was supported by the Japan Society for the Promotion of Science (grant number JP20K04066) and the NASA Nexus for Exoplanet System Science (NExSS) (grant number 80NSSC19KO461).

Featured image: The authors of this study: Dr. Christopher Reinhard (left) and Dr. Kazumi Ozaki (right). © Kazumi Ozaki

Reference: Ozaki, K., Reinhard, C.T. The future lifespan of Earth’s oxygenated atmosphere. Nat. Geosci. (2021). https://www.nature.com/articles/s41561-021-00693-5 https://doi.org/10.1038/s41561-021-00693-5

Provided by Toho University

Medicine

HKBU Develops Dual-targeting Drug For EBV-related Cancers (Medicine)

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A Hong Kong Baptist University-led (HKBU) research team has developed a novel drug which has the potential to become a next-generation treatment for cancers associated with Epstein–Barr virus (EBV).

The peptide-linked drug, which is responsive to the acidic environment found in tumours, is the first known agent to have successfully targeted two viral proteins that are simultaneously produced by EBV. It also offers a new strategy by increasing the uptake of anti-cancer drugs in tumour cells, thus allowing the application of lower drug dosages which helps reduce treatment side effects and health risks.

The research results were published in the international academic journal Advanced Science.

New drug targets two EBV-specific viral proteins

EBV is one of the most common viruses in humans, having infected more than 90% of the human population worldwide. It is widely known that the virus plays a key role in several cancers such as nasopharyngeal carcinoma (NPC), which is highly prevalent in Hong Kong and southern China.

Led by Professor Gary Wong Ka-Leung, Professor and Head of the Department of Chemistry at HKBU, Dr Lung Hong Lok, Assistant Professor of the Department of Chemistry at HKBU, and Dr Law Ga-lai, Associate Professor of the Department of Applied Biology and Chemical Technology at The Hong Kong Polytechnic University, the research team constructed a novel drug with a peptide, i.e., a component of the building blocks of various proteins, that can target two EBV-specific viral proteins – Latent membrane protein 1 (LMP1) and Epstein–Barr nuclear antigen 1 (EBNA1). They are the viral proteins which are expressed in all EBV-infected tumour cells, and both play a vital role in the development and progression of EBV-associated tumours.

Leveraging the success of the first-generation drugs developed by the research team in recent years, this novel dual-targeting drug employs the treatment mechanisms of: (1) targeting and binding to EBNA1, making it no longer functional, and (2) inhibiting LMP1 and serving as an imaging agent. Since LMP1 is more accessible to drug targeting due to its presence on the surface of cells, the ability of the new drug to selectively identify EBV-infected cancer cells is largely enhanced.

pH-sensitivity improves drug targeting

In addition, the researchers engineered the drug so that it has excellent sensitivity to an acidic environment. When the drug binds to a tumour cell, its peptide will cleave and be released in response to the acidic tumour microenvironment. It then enters the nucleus of the tumour cell and hinders the function of EBNA1. Since normal cells have a neutral environment, and cancer cells usually prevail in an acidic environment, the new drug’s excellent sensitivity to acidic environments can minimise its off-target rate. As a result, unintended damage to normal cells can be reduced.

The synergistic combination of pH sensitivity (in an acidic environment) and the specific targeting of an accessible surface protein (LMP1) will dramatically raise the new drug’s efficacy. The resulting increase in drug uptake rates will allow the application of a lower drug dosage and it will also minimise the side effects and health risks whilst maintaining the drug’s functions.

The study also showed that the drug can emit unique responsive fluorescent signals once it has bound to the viral proteins, illustrating its potential role in tumour cell imaging.

Animal model demonstrates drug efficacy and safety

The novel drug was tested in an animal model by injecting it into mice with EBV-positive NPC tumours. The results showed that a low drug dosage of 12.5 mg per kg of body weight could reduce the NPC tumour size by half. In addition, the average body weight of the mice increased slightly during the experimental period, indicating an improvement in their health condition.

“The experimental results are good indicators that prove the drug’s efficacy and safety. Since this is the first example of simultaneous imaging and inhibition of two EBV viral proteins, it can serve as a blueprint for a next-generation drug for the safe monitoring and treatment of a specific cancer,” said Professor Wong.

HKBU has established a spin-off company named BP InnoMed Limited (BPI) to further develop this new anti-EBV drug and carry out clinical trials. Recently, the company was named as the Best Public Communicator in the 2020 Bridging Research from Academia to Cancer Entrepreneurship Venture Competition, which was organised by the Asian Fund for Cancer Research. In 2020, BPI was also accepted by the Incu-Bio Program of the Hong Kong Science and Technology Park, and it will establish a laboratory there for preclinical analysis of the anti-EBV drugs.

Other members of the research team include Dr Di Jinming, Associate Professor of Surgery of The Third Affiliated Hospital at Sun Yat-sen University.

Featured image: A research team led by Professor Gary Wong Ka-Leung (centre), Dr Lung Hong Lok (right) and Dr Law Ga-lai develop a novel dual-targeting drug for treating cancers associated with EBV. © Hong Kong Baptist University

Reference: Zha, S., Chau, H.‐F., Chau, W. Y., Chan, L. S., Lin, J., Lo, K. W., Chi‐Shing, W., Yip, Y. L., Tsao, S. W., Farrell, P. J., Feng, L., Di, J. M., Law, G.‐L., Lung, H. L., Wong, K.‐L., Dual‐Targeting Peptide‐Guided Approach for Precision Delivery and Cancer Monitoring by Using a Safe Upconversion Nanoplatform. Adv. Sci. 2021, 2002919. https://doi.org/10.1002/advs.202002919

Provided by Hong Kong Baptist University

Biology

A Mechanism By Which Cells Build ‘Mini-muscles’ Underneath Their Nucleus Identified (Biology)

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Researchers identified a mechanism by which cells build ‘mini-muscles’ underneath their nucleus

Research groups at the University of Helsinki uncovered how motor protein myosin, which is responsible for contraction of skeletal muscles, functions also in non-muscle cells to build contractile structures at the inner face of the cell membrane. This is the first time when such ‘mini-muscles’, also known as stress fibers, have been seen to emerge spontaneously through myosin-driven reorganization of the pre-existing actin filament network in cells. Defects in the assembly of these ‘mini-muscles’ in cells lead to multiple disorders in humans, and in the most severe cases to cancer progression.

A new study published in eLife, drills into the core mechanisms of stress fiber assembly, and reveals how stress fibers can be built directly at the cell cortex: a specialized network of actin filaments on the inner face of the cell membrane. The research, carried out in the groups of Academy Professor Pekka Lappalainen at HiLIFE Institute of Biotechnology, and Docent Sari Tojkander at Faculty of Veterinary Medicine, University of Helsinki, uncovers that myosin pulses, which were previously connected to shape-changes in the epithelial tissues during animal development, can template assembly of stress fibers at the cell cortex. In this process, non-muscle myosin II, a close relative to the protein responsible for muscle contraction, is locally and temporally recruited to the cortex, where it organizes the initially mesh-like actin filament network into parallel rod-like structures. These structures then engage the growth and maturation of focal adhesions at the both ends of the actomyosin bundle, finally creating a stress fiber at the cell cortex (see Figure below).

On the Left : SUPER-RESOLUTION MICROSCOPY Image Of A MIGRATING HUMAN OSTEOSARCOMA CELL. MAGENTA MARKS FOCAL ADHESIONS, AND GREEN NON-MUSCLE MYOSIN II (NMII). F-ACTIN BUNDLES ARE SHOWN IN GREY. ON THE RIGHT: SCHEMATICS OF CORTICAL STRESS FIBER ASSEMBLY PROCESS. MYOSIN II PULSE ORCHESTRATES THE INITIAL ASSEMBLY AND MATURATION OF A CORTICAL STRESS FIBER, FOLLOWED BY FOCAL ADHESION MATURATION AT THE ENDS OF THE CONTRACTILE BUNDLE. NOTE THAT THE COLOR-CODING IS DIFFERENT BETWEEN THE TWO PANELS. CREDIT: JAAKKO LEHTIMÄki

“Previous studies from our group at University of Helsinki and other laboratories abroad demonstrated that stress fibers can arise at the front of the cell from small actin- and myosin-containing precursor structures, and that stress fibers disassemble at the back of the cell as it moves forward. Now we reveal a completely new mechanism by which stress fibers can form in cells, and provide an explanation for why ‘mysterious’ myosin pulses occur at the cell cortex,” Lappalainen comments.

“Intriguingly, we also observed that this type of stress fiber generation was most prominent under the nucleus, which stores all genetic information and is the largest organelle in our cells. It could be that cortical stress fibers protect the nucleus or aid the movement of the nucleus along with the rest of the cell body,” adds Dr. Jaakko Lehtimaki who is the lead author of this study.

The new findings bring forth an important new feature in the stress fiber toolbox. Cells in the three-dimensional tissue environment rarely display stress fiber precursors typically seen in cells migrating on a cell culture dish. Thus, myosin pulse-mediated assembly process enables assembly of contractile structures in cells migrating in various environments. Because myosin pulses have been witnessed in many different cell- and tissue types, this might serve as a universal mechanism for local force-production in the non-muscle tissues.

The role of myosin and actin proteins

The most abundant components of our muscles are myosin motor proteins, and bar-like filaments assembled from protein actin. Coordinated ‘crawling’ of myosin motor proteins along actin filaments is the principal mechanism that generates the force for muscle contraction. However, such myosin-based force-production is not limited to muscles, because also cells in other tissues within our bodies have similar contractile structures. These ‘mini-muscles’ of non-muscle cells, called stress fibers, are composed of the same central players (actin and myosin) as the contractile units of muscles.

Within our bodies, skeletal muscles attach to bones via tendons, whereas special adhesion structures named focal adhesions connect stress fibers to the surroundings of the cell. This enables the stress fibers to sense and emit forces between cells and their environment. In addition to being the major force-sensitive structures in cells, stress fibers are important for proper differentiation that is, specialization of cells to different tasks in the body. They also protect the nucleus when the cell is migrating in a challenging three-dimensional tissue environment. Consequently, defects in stress fiber assembly in cells contribute to multiple disorders, such as atherosclerosis, neuropathies, and cancer progression.

Featured image: Super-resolution microscopy image of a human osteosarcoma cell. © Jaakko Lehtimaki

Ori­ginal art­icle:

Lehtimäki JI, Rajakylä K, Tojkander S, Lappalainen P (2021). Generation of stress fibers through myosin-driven re-organization of the actin cortex. eLife Jan 28; 10:e60710 https://10.7554/eLife.60710

Provided by University of Helsinki