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Webb finds plethora of carbon molecules around ISO-ChaI 147, a young star

An international team of astronomers have used the NASA/ESA/Webb James Webb Space Telescope to study the disc around a young and very low-mass star. The results reveal the richest hydrocarbon chemistry seen to date in a protoplanetary disc (including the first extrasolar detection of ethane) and contribute to our evolving understanding of the diversity of planetary systems.

At the centre of the image, a bright light source illuminates a surrounding disc, the colour of which transitions from bright yellow to darker orange. The image background is black.
This is an artist’s impression of a young star surrounded by a protoplanetary disc.
An international team of astronomers have used the NASA/ESA/Webb James Webb Space Telescope to study the disc around a young and very low-mass star. The results reveal the richest hydrocarbon chemistry seen to date in a protoplanetary disc (including the first extrasolar detection of ethane) and contribute to our evolving understanding of the diversity of planetary systems.
The science team explored the region around a very low-mass star of 0.11 solar masses (known as ISO-ChaI 147). These observations provide insights into the environment as well as basic ingredients for such planets to form. The team found that the gas in the planet-forming region of the star is rich in carbon. This could potentially be because carbon is removed from the solid material from which rocky planets can form, and could explain why Earth is relatively carbon-poor.
Credit: NASA/JPL-Caltech

Planets form in discs of gas and dust orbiting young stars. Observations indicate that terrestrial planets are expected to form more efficiently than gas giants in the discs around very low-mass stars. While very low-mass stars have the highest rate of occurrence of orbiting rocky planets, their planetary compositions are largely unknown. For example, the Trappist-1 system (which Webb has studied) consists of seven rocky planets within 0.1 au [1] and their composition is generally assumed to be Earth-like. However, new data from Webb suggests that discs around very low-mass stars may evolve differently from those around more massive stars.

The MIRI Mid-INfrared Disk Survey (MINDS) aims to build a bridge between the chemical inventory of discs and the properties of exoplanets. In a new study, this team explored the region around a very low-mass star of 0.11 solar masses (known as ISO-ChaI 147). These observations provide insights into the environment as well as basic ingredients for such planets to form. The team found that the gas in the planet-forming region of the star is rich in carbon. This could potentially be because carbon is removed from the solid material from which rocky planets can form, and could explain why Earth is relatively carbon-poor.

“Webb has a better sensitivity and spectral resolution than previous infrared space telescopes,” explained lead author Aditya Arabhavi of the University of Groningen in the Netherlands. These observations are not possible from Earth, because the emissions are blocked by the atmosphere. Previously we could only identify acetylene (C2H2) emission from this object. However, Webb’s higher sensitivity and spectral resolution allowed us to detect weak emission from less abundant molecules. Webb also allowed us to understand that these hydrocarbon molecules are not just diverse but also abundant.”

This graphic presents some of the results from the MIRI Mid-INfrared Disk Survey (MINDS), which aims to build a bridge between the chemical inventory of discs and the properties of exoplanets. In a new study, the science team explored the region around a very low-mass star of 0.11 solar masses (known as ISO-ChaI 147). These observations provide insights into the environment as well as basic ingredients for such planets to form. The team found that the gas in the planet-forming region of the star is rich in carbon. This could potentially be because carbon is removed from the solid material from which rocky planets can form, and could explain why Earth is relatively carbon-poor.The spectrum revealed by Webb’s Mid-InfraRed Instrument (MIRI) shows the richest hydrocarbon chemistry seen to date in a protoplanetary disc, consisting of 13 carbon-bearing molecules up to benzene. This includes the first extrasolar detection of ethane (C2H6), the largest fully-saturated hydrocarbon detected outside our Solar System. Since fully-saturated hydrocarbons are expected to form from more basic molecules, detecting them here gives researchers clues about the chemical environment. The team also successfully detected ethylene (C2H4), propyne (C3H4), and the methyl radical CH3, for the first time in a protoplanetary disc.

This graphic highlights the detections of ethane (C2H6), methane (CH4), propyne (C3H4), cyanoacetylene (HC3N), and the methyl radical CH3.

Credit:
NASA, ESA, CSA, R. Crawford (STScI)
This graphic presents some of the results from the MIRI Mid-INfrared Disk Survey (MINDS), which aims to build a bridge between the chemical inventory of discs and the properties of exoplanets. In a new study, the science team explored the region around a very low-mass star of 0.11 solar masses (known as ISO-ChaI 147). These observations provide insights into the environment as well as basic ingredients for such planets to form. The team found that the gas in the planet-forming region of the star is rich in carbon. This could potentially be because carbon is removed from the solid material from which rocky planets can form, and could explain why Earth is relatively carbon-poor.
The spectrum revealed by Webb’s Mid-InfraRed Instrument (MIRI) shows the richest hydrocarbon chemistry seen to date in a protoplanetary disc, consisting of 13 carbon-bearing molecules up to benzene. This includes the first extrasolar detection of ethane (C2H6), the largest fully-saturated hydrocarbon detected outside our Solar System. Since fully-saturated hydrocarbons are expected to form from more basic molecules, detecting them here gives researchers clues about the chemical environment. The team also successfully detected ethylene (C2H4), propyne (C3H4), and the methyl radical CH3, for the first time in a protoplanetary disc.
This graphic highlights the detections of ethane (C2H6), methane (CH4), propyne (C3H4), cyanoacetylene (HC3N), and the methyl radical CH3.
Credit: NASA, ESA, CSA, R. Crawford (STScI)

The spectrum revealed by Webb’s Mid-InfraRed Instrument (MIRI) shows the richest hydrocarbon chemistry seen to date in a protoplanetary disc, consisting of 13 carbon-bearing molecules up to benzene. This includes the first extrasolar detection of ethane (C2H6), the largest fully-saturated hydrocarbon [2] detected outside our Solar System. Since fully-saturated hydrocarbons are expected to form from more basic molecules, detecting them here gives researchers clues about the chemical environment. The team also successfully detected ethylene (C2H4), propyne (C3H4), and the methyl radical CH3, for the first time in a protoplanetary disc.

“These molecules have already been detected in our Solar System, for example in comets such as 67P/Churyumov–Gerasimenko and C/2014 Q2 (Lovejoy),” adds Arabhavi. “It is amazing that we can now see the dance of these molecules in the planetary cradles. It is a very different planet-forming environment from what we usually think of.”

The team indicates that these results have large implications for astrochemistry in the inner 0.1 au and the planets forming there. “This is profoundly different from the composition we see in discs around solar-type stars, where oxygen bearing molecules dominate (like carbon dioxide and water),” added team member Inga Kamp, also of the University of Groningen. “This object establishes that these are a unique class of objects.”

“It’s incredible that we can detect and quantify the amount of molecules that we know well on Earth, such as benzene, in an object that is more than 600 light-years away,” added team member Agnés Perrin of Centre National de la Recherche Scientifique in France.

Next, the science team intend to expand their study to a larger sample of such discs around very low-mass stars to develop their understanding of how common such exotic carbon-rich terrestrial planet forming regions are. “The expansion of our study will also allow us to better understand how these molecules can form,” explained team member and PI of the MINDS programme, Thomas Henning, of the Max Planck Institute for Astronomy in Germany. “Several features in the Webb data are also still unidentified, so more spectroscopy is required to fully interpret our observations.”

This work also highlights the crucial need for scientists to collaborate across disciplines. The team notes that these results and the accompanying data can contribute towards other fields including theoretical physics, chemistry and astrochemistry, to interpret the spectra and to investigate new features in this wavelength range.

These results have been published in the journal Science.

Notes

[1] An astronomical unit (AU, or au) is a unit of length effectively equal to the average, or mean, distance between Earth and the Sun, which is defined as roughly 150 million kilometres.

[2] Saturated hydrocarbons are molecules that are made entirely of single carbon-carbon bonds. They cannot incorporate additional atoms into their structure, and are therefore said to be saturated.

 

Press release from ESA Webb.

Webb finds carbon source on surface of Jupiter’s moon Europa

Jupiter’s moon Europa is one of a handful of worlds in our Solar System that could potentially harbour conditions suitable for life. Previous research has shown that beneath its water-ice crust lies a salty ocean of liquid water with a rocky seafloor. However, planetary scientists had not confirmed whether or not that ocean contained the chemicals needed for life, particularly carbon.

Europa (NIRCam image)
Webb’s NIRCam (Near Infrared Camera) captured this picture of the surface of Jupiter’s moon Europa. Webb identified carbon dioxide on the icy surface of Europa that likely originated in the moon’s subsurface ocean. This discovery has important implications for the potential habitability of Europa’s ocean. The moon appears mostly blue because it is brighter at shorter infrared wavelengths. The white features correspond with the chaos terrain Powys Regio (left) and Tara Regio (centre and right), which show enhanced carbon dioxide ice on the surface.
Credit:
NASA, ESA, CSA, G. Villanueva (NASA/GSFC), S. Trumbo (Cornell Univ.), A. Pagan (STScI)

Astronomers using data from the NASA/ESA/CSA James Webb Space Telescope have identified carbon dioxide in a specific region on the icy surface of Europa. Analysis indicates that this carbon likely originated in the subsurface ocean and was not delivered by meteorites or other external sources. Moreover, it was deposited on a geologically recent timescale. This discovery has important implications for the potential habitability of Europa’s ocean.

On Earth, life likes chemical diversity — the more diversity, the better. We’re carbon-based life. Understanding the chemistry of Europa’s ocean will help us determine whether it’s hostile to life as we know it, or whether it might be a good place for life,

said Geronimo Villanueva of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, lead author of one of two independent papers describing the findings.

We now think that we have observational evidence that the carbon we see on Europa’s surface came from the ocean. That’s not a trivial thing. Carbon is a biologically essential element,

added Samantha Trumbo of Cornell University in Ithaca, New York, lead author of the second paper analysing this data.

NASA plans to launch its Europa Clipper spacecraft, which will perform dozens of close flybys of Europa to further investigate whether it could have conditions suitable for life, in October 2024.

A Surface-Ocean Connection

Webb finds that on Europa’s surface, carbon dioxide is most abundant in a region called Tara Regio — a geologically young area of generally resurfaced terrain known as ‘chaos terrain’. The surface ice has been disrupted, and there has likely been an exchange of material between the subsurface ocean and the icy surface.

Previous observations from the Hubble Space Telescope show evidence for ocean-derived salt in Tara Regio,” explained Trumbo. “Now we’re seeing that carbon dioxide is heavily concentrated there as well. We think this implies that the carbon probably has its ultimate origin in the internal ocean.

Scientists are debating to what extent Europa’s ocean connects to its surface. I think that question has been a big driver of Europa exploration,” said Villanueva. “This suggests that we may be able to learn some basic things about the ocean’s composition even before we drill through the ice to get the full picture.

Both teams identified the carbon dioxide using data from the integral field unit of Webb’s Near-Infrared Spectrograph (NIRSpec). This instrument mode provides spectra with a resolution of 320 x 320 kilometres over a field of view of diameter 3128 kilometres on the surface of Europa, allowing astronomers to determine where specific chemicals are located.

Map of Europa's surface
This graphic shows a map of Europa’s surface with NIRCam (Near Infrared Camera) in the first panel and compositional maps derived from NIRSpec/IFU (Near Infrared Spectrograph’s Integral Field Unit) data in the following three panels. In the compositional maps, the white pixels correspond to carbon dioxide in the large-scale region of disrupted chaos terrain known as Tara Regio (centre and right), with additional concentrations within portions of the chaos region Powys Regio (left). The second and third panels show evidence of crystalline carbon dioxide, while the fourth panel indicates a complexed and amorphous form of carbon dioxide.
Astronomers using Webb have found carbon on the chaos terrain of Tara Regio and Powys Regio. Surface ices in these regions have been disrupted, and there has likely been a relatively recent exchange of material between the subsurface ocean and the icy surface. Carbon, a universal building block for life as we know it, likely originated in Europa’s ocean. The discovery suggests a potentially habitable environment in the salty subsurface ocean of Europa.
The NIRSpec/IFU images appear pixelated because Europa is 10 x 10 pixels across in the detector’s field of view.
Credit:
NASA, ESA, CSA, G. Villanueva (NASA/GSFC), S. Trumbo (Cornell Univ.), A. Pagan (STScI)

Carbon dioxide isn’t stable on Europa’s surface. Therefore, the scientists say it’s likely that it was supplied on a geologically recent timescale — a conclusion bolstered by its concentration in a region of young terrain.

These observations only took a few minutes of the observatory’s time,

said Heidi Hammel of the Association of Universities for Research in Astronomy, a Webb interdisciplinary scientist leading Webb’s Cycle 1 Guaranteed Time Observations of the Solar System.

Even in this short period of time, we were able to do really big science. This work gives a first hint of all the amazing Solar System science we’ll be able to do with Webb.”

Searching for a Plume

Villanueva’s team also looked for evidence of a plume of water vapour erupting from Europa’s surface. Researchers using the NASA/ESA Hubble Space Telescope reported tentative detections of plumes in 2013, 2016, and 2017. However, finding definitive proof has been difficult.

The new Webb data show no evidence of plume activity, which allowed Villanueva’s team to set a strict upper limit on the rate at which material is potentially being ejected. The team stressed, however, that their non-detection does not rule out a plume.

There is always a possibility that these plumes are variable and that you can only see them at certain times. All we can say with 100% confidence is that we did not detect a plume at Europa when we made these observations with Webb,” said Hammel.

These findings may help inform NASA’s Europa Clipper mission, as well as ESA’s Jupiter Icy Moons Explorer, Juice, which was launched on 14 April 2023. Juice will make detailed observations of the giant gas planet and its three large ocean-bearing moons — Ganymede, Callisto and Europa — with a suite of remote sensing, geophysical and in situ instruments. The mission will characterise these moons as both planetary objects and possible habitats, explore Jupiter’s complex environment in depth, and study the wider Jupiter system as an archetype for gas giants across the Universe.

This is a great first result of what Webb will bring to the study of Jupiter’s moons,” said co-author Guillaume Cruz-Mermy, formerly of Université Paris-Saclay and current ESA Research Fellow at the European Space Astronomy Centre. “I’m looking forward to seeing what else we can learn about their surface properties from these and future observations.

The two papers associated with this research will be published in Science on 21 September 2023.

Europa (NIRCam image, cropped)
Webb’s NIRCam (Near Infrared Camera) captured this picture of the surface of Jupiter’s moon Europa. Webb identified carbon dioxide on the icy surface of Europa that likely originated in the moon’s subsurface ocean. This discovery has important implications for the potential habitability of Europa’s ocean. The moon appears mostly blue because it is brighter at shorter infrared wavelengths. The white features correspond with the chaos terrain Powys Regio (left) and Tara Regio (centre and right), which show enhanced carbon dioxide ice on the surface.
Credit:
NASA, ESA, CSA, G. Villanueva (NASA/GSFC), S. Trumbo (Cornell Univ.), A. Pagan (STScI)

 

Press release from ESA Webb.

Images are one of the best means to celebrate the beauty of science and to explore any biological topic. Computational science and advanced tools highlight basic cell functions, the darkness of disease, environmental questions and – as the editors explain – how complexity generates richness in unexpected ways.

The Art of Theoretical Biology is a collection of pieces of art; they are the result of a deep scientific research, of data analysis and mathematical models; and they may help us make science more accessible to the public as well.

More than 120 authors contributed to this book, creating a synergic union between art and science: a promising new way to show how the potential of mathematical models may support discoveries in any field.

We had the honour and the pleasure to interview the editors of this book: Franziska Matthäus, Giersch Professor of Bioinformatics at the Goethe University, Frankfurt; Sebastian Matthäus, founder and head at the Grenfarben Agentur für Gestaltung, Berlin; Sarah Anne Harris, Associate Professor of Biological Physics at the University of Leeds; Thomas Hillen, Professor and Associate Chair Research at the Department of Mathematical and Statistical Sciences at the University of Alberta.

Cellular Swarms in Cellular Automata by Andreas Deutsch. The Art of Theoretical Biology, p. 105. © 2020 Springer

1) In the preface, it is explained that you conceive “the book as a superposition of art and science; each separate image is an act of scientific research, but the whole collection is a work of art”.  From an educational point of view, do you think it would be possible to profit from the conjoined usage of art and science to get closer to the audience?

Yes, our intention was to use the power of images to reach out to non-scientists and increase awareness of and interest in the increasingly important field of theoretical biology. The stories behind each image are formulated in a very compact style free of scientific jargon, and targeted to a wider audience using the scientists’ own words. While most people outside the scientific community would not, out of plain intrinsic interest, read scientific articles, they are nonetheless attracted to the images and become curious, especially because for most of the images it is not immediately apparent what is displayed. Connecting the images to the research story and the creation process allows the reader a short journey into a variety of exciting research topics. We hope that our book will show readers that science is exciting and full of beauty.

2. A significant part of the book concerns oncological research, for the purpose of improving patient treatment and decreasing cancer mortality rates. What are the future perspectives of predictive studies on carcinogenesis by means of mathematical models?

Oncological research profits from a tight collaboration between medics, biologists and mathematical modelers. Validating our predictive models against experimental data can be far more challenging than for inanimate matter. Cancer occurs in living organisms, which are extremely complex and need to be treated with particular care. However, tissue engineers can now grow “tumoroids”, which are synthetic cell cultures that grow into tumor-like tissue, and which can then be studied in a more controlled manner. These synthetic systems are likely to accelerate our understanding of how best to model carcinogenesis.

Moreover, the advent of new technologies such as automated image processing (e.g. of biopsies and scans) and artificial intelligence have generated large interest from the clinical sciences, so increasingly both data science and mathematical modelling are informing medical research and treatment of disease. The future of cancer therapy is likely to be “personalized” or “precision medicine”, where each patient receives a treatment bespoke to their particular disease, which may be based on the genetic profile of their tumour. An exciting example where mathematical modelling is at the forefront of development in precision medicine is adaptive evolutionary therapies. These can drastically reduce side effects, reduce chemotherapeutic resistance and improve patients’ quality of life.

Art Theoretical Biology
Crop Circles of Cancer by Katharina Baum, Jagath C. Rajapakse & Francisco Azuaje. The Art of Theoretical Biology, p. 73. © 2020 Springer

3. Mathematical models may be used in order to develop drugs and to simulate their pharmacokinetics. Thanks to this approach, what progress has been made as regards pharmacological drug development?

For pharmacokinetics, there has been a great deal of progress in the use of pre-clinical models to predict the behavior of drugs in patients in relation to their duration of action, absorption, metabolism, excretion and toxicity. These models use experiments that expose cultured cells and or microsomes (which are highly simplified mimics of organs) to the drug in the laboratory to predict how it will behave in animals.

However, de novo drug design from the molecular level upwards is a very complicated and expensive process. Big pharma companies have recognized the value in computer aided design in optimizing new molecules for further development. However, the enormous complexity of drug interactions, which includes practical details such as solubility and bioavailability, cell penetration, off-target interactions that cause side effects, potential degradation by metabolic enzymes and time to excretion mean that multiple different types of models must be used, depending on aspect of drug development that is being optimized.

Art Theoretical Biology
Knitting Proteins by Santiago Schnell. The Art of Theoretical Biology, p. 55. © 2020 Springer

4. At present, how determining has been the contribution of theoretical biology to the scientific research? How important is its predictive purpose, in order to improve quality?

The ultimate aim of theoretical biology is to understand living systems, to be able to make predictions about their behavior and to give us the insight we need to engineer them. Models have been used successfully to describe biology at every length-scale, from the movement of electrons during photosynthesis at the sub-atomic level, through to the atomic interactions that drive protein-protein interactions (Knitting Proteins by Santiago Schnell) and molecular signaling cascades (Crop Circles of Cancer by Katharina Baum, Jagath C. Rajapakse & Francisco Azuaje), up to cell dynamics (Cellular Swarms in Cellular Automata by Andreas Deutsch), the biomechanics of organs, and eventually ecological interactions of populations and their response to their environments (Tower of Life by Sylvain Gretchko).

However, what our models are not yet able to do, is to cross these different theoretical regimes. While we can successfully build models at individual length-scales, e.g. for single proteins, or for collections of cells, or for the heart, or the population of a species, we cannot predict how a change at any one of these length-scales will impact the others. For example, when clinical geneticists sequence the genomes of their patients to understand the origin of their disease, they find many “variants of unknown significance”. Genetic variation is so prevalent that it is often impossible to identify the mutations responsible for a genetic disease. While we can say precisely how a mutation will affect the atomic structure of DNA, we cannot predict how this atomic level change will affect the next length-scales up, such as cells or tissues. A major breakthrough in theoretical biology will be when we can trace the information flow between the multi-length scales, so from atomic level changes through to cells and organs, that are all important in biology.

To understand, predict and control a biological system is the ultimate goal of theoretical biology. Scientific merit is measured directly through its implication on science, biology, ecology, or medicine. Theoretical biology is developing fast, many aspects of the experimental data lack reproducibility, because we don’t understand the variables. Models can help with this.

5. The field of theoretical biology also contributes to the study of nature and of environmental impact assessments. Habitat alterations of several species are one of the main anthropic threats to biodiversity. What potential have mathematical tools in the field of ecological issues?

Theoretical biology plays a major role in ecology. Modelling is used to manage fishing quotas, to design protective marine areas, and to control invasive species, such as mountain pine beetles in Western Canada. Modelling is the only way to address vital questions about the future of our planet, such as looming species extinctions and the effect on predator-prey dynamics, biodiversity, evolution. Models enable us to make predictions about the impact of climate change, and to provide scientific strategies to mitigate against the consequences.

Art Theoretical Biology
Tower of Life by Sylvain Gretchko. The Art of Theoretical Biology, p. 123. © 2020 Springer

Reference: The Art of Theoretical Biology; Matthäus, F., Matthäus, S., Harris, S., Hillen, Th. (Eds.) © 2020 Springer LINK TO THE BOOK.

Why are plants green?

UC Riverside-led research team’s model to explain photosynthesis lays out the next challenging phase of research on how green plants transform light energy into chemical energy

UC Riverside-led research team’s model to explain photosynthesis lays out the next challenging phase of research on how green plants transform light energy into chemical energy. Credits: Gabor lab, UC Riverside

When sunlight shining on a leaf changes rapidly, plants must protect themselves from the ensuing sudden surges of solar energy. To cope with these changes, photosynthetic organisms — from plants to bacteria — have developed numerous tactics. Scientists have been unable, however, to identify the underlying design principle.

An international team of scientists, led by physicist Nathaniel M. Gabor at the University of California, Riverside, has now constructed a model that reproduces a general feature of photosynthetic light harvesting, observed across many photosynthetic organisms.

Nathaniel Gabor is an associate professor of physics at UC Riverside. Credits: CIFAR

Light harvesting is the collection of solar energy by protein-bound chlorophyll molecules. In photosynthesis — the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water — light energy harvesting begins with sunlight absorption.

The researchers’ model borrows ideas from the science of complex networks, a field of study that explores efficient operation in cellphone networks, brains, and the power grid. The model describes a simple network that is able to input light of two different colors, yet output a steady rate of solar power. This unusual choice of only two inputs has remarkable consequences.

“Our model shows that by absorbing only very specific colors of light, photosynthetic organisms may automatically protect themselves against sudden changes — or ‘noise’ — in solar energy, resulting in remarkably efficient power conversion,” said Gabor, an associate professor of physics and astronomy, who led the study appearing today in the journal Science. “Green plants appear green and purple bacteria appear purple because only specific regions of the spectrum from which they absorb are suited for protection against rapidly changing solar energy.”

Gabor first began thinking about photosynthesis research more than a decade ago, when he was a doctoral student at Cornell University. He wondered why plants rejected green light, the most intense solar light.  Over the years, he worked with physicists and biologists worldwide to learn more about statistical methods and the quantum biology of photosynthesis.

Richard Cogdell, a renowned botanist at the University of Glasgow in the United Kingdom and a coauthor on the research paper, encouraged Gabor to extend the model to include a wider range of photosynthetic organisms that grow in environments where the incident solar spectrum is very different.

“Excitingly, we were then able to show that the model worked in other photosynthetic organisms besides green plants, and that the model identified a general and fundamental property of photosynthetic light harvesting,” he said. “Our study shows how, by choosing where you absorb solar energy in relation to the incident solar spectrum, you can minimize the noise on the output — information that can be used to enhance the performance of solar cells.”

Coauthor Rienk van Grondelle, an influential experimental physicist at Vrije Universiteit Amsterdam in the Netherlands who works on the primary physical processes of photosynthesis, said the team found the absorption spectra of certain photosynthetic systems select certain spectral excitation regions that cancel the noise and maximize the energy stored.

“This very simple design principle could also be applied in the design of human-made solar cells,” said van Grondelle, who has vast experience with photosynthetic light harvesting.

Gabor explained that plants and other photosynthetic organisms have a wide variety of tactics to prevent damage due to overexposure to the sun, ranging from molecular mechanisms of energy release to physical movement of the leaf to track the sun. Plants have even developed effective protection against UV light, just as in sunscreen.

“In the complex process of photosynthesis, it is clear that protecting the organism from overexposure is the driving factor in successful energy production, and this is the inspiration we used to develop our model,” he said. “Our model incorporates relatively simple physics, yet it is consistent with a vast set of observations in biology. This is remarkably rare. If our model holds up to continued experiments, we may find even more agreement between theory and observations, giving rich insight into the inner workings of nature.”

To construct the model, Gabor and his colleagues applied straightforward physics of networks to the complex details of biology, and were able to make clear, quantitative, and generic statements about highly diverse photosynthetic organisms.

“Our model is the first hypothesis-driven explanation for why plants are green, and we give a roadmap to test the model through more detailed experiments,” Gabor said.

Photosynthesis may be thought of as a kitchen sink, Gabor added, where a faucet flows water in and a drain allows the water to flow out. If the flow into the sink is much bigger than the outward flow, the sink overflows and the water spills all over the floor.

“In photosynthesis, if the flow of solar power into the light harvesting network is significantly larger than the flow out, the photosynthetic network must adapt to reduce the sudden over-flow of energy,” he said. “When the network fails to manage these fluctuations, the organism attempts to expel the extra energy. In doing so, the organism undergoes oxidative stress, which damages cells.”

The researchers were surprised by how general and simple their model is.

“Nature will always surprise you,” Gabor said. “Something that seems so complicated and complex might operate based on a few basic rules. We applied the model to organisms in different photosynthetic niches and continue to reproduce accurate absorption spectra. In biology, there are exceptions to every rule, so much so that finding a rule is usually very difficult. Surprisingly, we seem to have found one of the rules of photosynthetic life.”

Gabor noted that over the last several decades, photosynthesis research has focused mainly on the structure and function of the microscopic components of the photosynthetic process.

“Biologists know well that biological systems are not generally finely tuned given the fact that organisms have little control over their external conditions,” he said. “This contradiction has so far been unaddressed because no model exists that connects microscopic processes with macroscopic properties. Our work represents the first quantitative physical model that tackles this contradiction.”

Next, supported by several recent grants, the researchers will design a novel microscopy technique to test their ideas and advance the technology of photo-biology experiments using quantum optics tools.

“There’s a lot out there to understand about nature, and it only looks more beautiful as we unravel its mysteries,” Gabor said.

Gabor, Cogdell, and van Grondelle were joined in the research by Trevor B. Arp, Jed Kistner-Morris, and Vivek Aji at UCR.

The research was supported by the Air Force Office of Scientific Research Young Investigator Program, the National Science Foundation, and through a U.S. Department of the Navy’s Historically Black Colleges and Universities/Minority Institutions award. Gabor was also supported through a Cottrell Scholar Award and a Canadian Institute for Advanced Research Azrieli Global Scholar Award. Other sources of funding were the NASA MUREP Institutional Research Opportunity program, the U.S. Department of Energy, the Biotechnological and Biological Sciences Research Council, the Royal Netherlands Academy of Arts and Sciences, and the Canadian Institute for Advanced Research.

The research paper is titled, “Quieting a noisy antenna reproduces photosynthetic light harvesting spectra.”

 

 

 

Press release from the University of California, Riverside

Scientists identify a temperature tipping point for tropical forests

point tropical forests
An aerial view of a tropical forest along the eastern Pacific Ocean shoreline of Barro Colorado Island, Panama. Credit: Smithsonian Tropical Research Institute photo

A study in Science by 225 researchers working with data from 590 forest sites around the world concludes that tropical forests release much more carbon into the atmosphere at high temperatures.

All living things have tipping points: points of no return, beyond which they cannot thrive. A new report in Science shows that maximum daily temperatures above 32.2 degrees Celsius (about 90 degrees Fahrenheit) cause tropical forests to lose stored carbon more quickly. To prevent this escape of carbon into the atmosphere, the authors, including three scientists affiliated with the Smithsonian Tropical Research Institute in Panama, recommend immediate steps to conserve tropical forests and stabilize the climate.

Carbon dioxide is an important greenhouse gas, released as we burn fossil fuels. It is absorbed by trees as they grow and stored as wood. When trees get too hot and dry they may close the pores in their leaves to save water, but that also prevents them from taking in more carbon. And when trees die, they release stored carbon back into the atmosphere.

Tropical forests hold about 40 percent of all the carbon stored by land plants. For this study, researchers measured the ability of tropical forests in different sites to store carbon.

“Tropical forests grow across a wide range of climate conditions,” said Stuart Davies, director of Smithsonian ForestGEO, a worldwide network of 70 forest study sites in 27 countries. “By examining forests across the tropics, we can assess their resilience and responses to changes in global temperatures. Many other studies explored how individual forests respond to short-term climatic fluctuations. This study takes a novel approach by exploring the implications of thermal conditions currently experienced by all tropical forests.”

By comparing carbon storage in trees at almost 600 sites around the world that are part of several different forest monitoring initiatives: RAINFORAfriTRONT-FORCES and the Smithsonian’s ForestGEO, the huge research team led by Martin Sullivan from the University of Leeds and Manchester Metropolitan University found major differences in the amount of carbon stored by tropical forests in South America, Africa, Asia and Australia. South American forests store less carbon than forests in the Old World, perhaps due to evolutionary differences in which tree species are growing there.

They also found that the two most important factors predicting how much carbon is lost by forests are the maximum daily temperature and the amount of precipitation during the driest times of the year.

As temperatures reach 32.2 degrees Celsius, carbon is released much faster. Trees can deal with increases in the minimum nighttime temperature (a global warming phenomenon observed at some sites), but not with increases in maximum daytime temperature.

They predict that South American forests will be the most affected by global warming because temperatures there are already higher than on other continents and the projections for future warming are also highest for this region. Increasing carbon in the atmosphere may counterbalance some of this loss but would also exacerbate warming.

Forests can adapt to warming temperatures, but it takes time. Tree species that cannot take the heat die and are gradually replaced by more heat-tolerant species. But that may take several human generations.

“This study highlights the importance of protecting tropical forests and stabilizing the Earth’s climate,” said Jefferson Hall, co-author and director of the Smithsonian’s Agua Salud Project in Panama. “One important tool will be to find novel ways to restore degraded land, like planting tree species that help make tropical forests more resilient to the realities of the 21st century.” The Agua Salud project asks how native tree species adapted to an area can be used to manage water, store carbon and promote biodiversity conservation at a critical point where North and South America connect.

An aerial view of a tropical forest on the eastern Pacific Ocean shoreline of Barro Colorado Island, Panama. Credit: Smithsonian Tropical Research Institute photo
A relevant note:

One of the oldest permanent tropical forest study sites, located on Barro Colorado Island in Panama, is not being monitored for the first time in 40 years as a result of the COVID-19 pandemic, giving scientists less of a handle on any climate change effects that may be taking place.

Steve Paton, director of STRI’s physical monitoring program notes that in 2019 there were 32 days with maximum temperatures over 32 degrees Celsius at a weather station in the forest canopy on the Island and a first glance at his data indicates that these exceptionally hot days are becoming more common.

The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The Institute furthers the understanding of tropical biodiversity and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.

The paper Long-term thermal sensitivity of Earth’s tropical forests is published in Science 22 May 2020 (DOI: 10.1126/science.aaw7578)

 

Press release from the Smithsonian Tropical Research Institute

When pollen is in short supply, bumblebees damage plant leaves in a way that accelerates flower production, as an ETH research team headed up by Consuelo De Moraes and Mark Mescher has demonstrated.

Spring has sprung earlier than ever before this year, accompanied by temperatures more typical of early summertime. Many plants were already in full bloom by mid-​April, about three to four weeks earlier than normal. These types of seasonal anomalies are becoming increasingly frequent due to climate change, and the resulting uncertainty threatens to disrupt the timing of mutualistic relationships between plants and their insect pollinators.

A research team led by ETH Professors Consuelo De Moraes and Mark Mescher has now discovered that one peculiar bumblebee behaviour may help to overcome such challenges by facilitating coordination between the bees and the plants they pollinate. The group has found that bumblebee workers use their mouth parts to pinch into the leaves of plants that haven’t flowered yet, and that the resulting damage stimulates the production of new flowers that bloom earlier than those on plants that haven’t been given this “nudge”.

Their study has just been published in the journal Science. “Previous work has shown that various kinds of stress can induce plants to flower, but the role of bee-​inflicted damage in accelerating flower production was unexpected,” Mescher says.

bumblebees pollen
If bumblebees find too little pollen, they pierce the leaves of non-flowering plants in order to force them to produce flowers more quickly. Credits: Photograph: Hannier Pulido / ETH Zurich

Surprising behaviour from bumblebees

The researchers first noticed the behaviour during other experiments being undertaken by one of the authors, Foteini Pashalidou: pollinators were biting the leaves of test plants in the greenhouse. “On further investigation, we found that others had also observed such behaviours, but no one had explored what the bees were doing to the plants or reported an effect on flower production,” Mescher explains.

Following up on their observations, the ETH researchers devised several new laboratory experiments, and also conducted outdoor studies using commercially available bumblebee colonies – typically sold for the pollination of agricultural crops – and a variety of plant species.

Based on their lab studies, the researchers were able to show that the bumblebees’ propensity to damage leaves has a strong correlation with the amount of pollen they can obtain: Bees damage leaves much more frequently when there is little or no pollen available to them. They also found that damage inflicted on plant leaves had dramatic effects on flowering time in two different plant species. Tomato plants subjected to bumblebee biting flowered up to 30 days earlier than those that hadn’t been targeted, while mustard plants flowered about 14 days earlier when damaged by the bees.

“The bee damage had a dramatic influence on the flowering of the plants – one that has never been described before,” De Moraes says. She also suggests that the developmental stage of the plant when it is bitten by bumblebees may influence the degree to which flowering is accelerated, a factor the investigators plan to explore in future work.

The researchers tried to manually replicate the damage patterns caused by bees to see if they could reproduce the effect on flowering time. But, while this manipulation did lead to somewhat earlier flowering in both plant species, the effect was not nearly as strong as that caused by the bees themselves. This leads De Moraes to suggest that some chemical or other cue may also be involved. “Either that or our manual imitation of the damage wasn’t accurate enough,” she says. Her team is currently trying to identify the precise cues responsible for inducing flowering and characterising the molecular mechanisms involved in the plant response to bee damage.

 

Phenomenon also observed in the field

The ETH research team was also able to observe the bees’ damaging behaviour under more natural conditions, with doctoral student Harriet Lambert leading follow-​up studies on the rooftops of two ETH buildings in central Zurich. In these experiments, the researchers again observed that hungry bumblebees with insufficient pollen supplies frequently damaged the leaves of non-​blooming plants. But the damaging behaviour was consistently reduced when the researchers made more flowers available to the bees.

Furthermore, it was not only captive-​bred bumblebees from the researchers’ experimental colonies that damaged plant leaves. The investigators also observed wild bees from at least two additional bumblebee species biting the leaves of plants in their experimental plots. Other pollinating insects, such as honeybees, did not exhibit such behaviour, however: they seemed to ignore the non-​flowering plants entirely, despite being frequent visitors to nearby patches of flowering plants.

Delicate balance starting to tip

“Bumblebees may have found an effective method of mitigating local shortages of pollen,” De Moraes says. “Our open fields are abuzz with other pollinators, too, which may also benefit from the bumblebees’ efforts.” But it remains to be seen whether this mechanism is sufficient to overcome the challenges of changing climate. Insects and flowering plants have evolved together, sharing a long history that strikes a delicate balance between efflorescence and pollinator development. However, global warming and other anthropogenic environmental changes have the potential to disrupt the timing of these and other ecologically important interactions among species. Such rapid environmental change could result in insects and plants becoming increasingly out of sync in their development, for example. “And that’s something from which both sides stand to lose,” Mescher says.

 

Reference paper on bumblebees when pollen is in short supply

 

Paschalidou FG, Lambert H, Peybernes T, Mescher MC, De Moraes CM. Bumble bees damage plant leaves and accelerate flower production when pollen is scarce. Science, published online May 21st 2020. DOI: 10.1126/science.aay0496

 

Press release from ETH Zürich

Researchers from the Hubrecht Institute in Utrecht, Erasmus MC University Medical Center Rotterdam, and Maastricht University in the Netherlands have found that the coronavirus SARS-CoV-2, which causes COVID-19, can infect cells of the intestine and multiply there. Using state-of-the-art cell culture models of the human intestine, the researchers have successfully propagated the virus in vitro, and monitored the response of the cells to the virus, providing a new cell culture model for the study of COVID-19. These findings could explain the observation that approximately one third of COVID-19 patients experience gastrointestinal symptoms such as diarrhea, and the fact that the virus often can be detected in stool samples. The results of this study were published in the scientific journal Science on the 1st of May 2020.

Patients with COVID-19 show a variety of symptoms associated with respiratory organs – such as coughing, sneezing, shortness of breath, and fever – and the disease is transmitted via tiny droplets that are spread mainly through coughing and sneezing. One third of the patients however also have gastrointestinal symptoms, such as nausea and diarrhea. In addition, the virus can be detected in human stool long after the respiratory symptoms have been resolved. This suggests that the virus can also spread via so-called “fecal-oral transmission”.

Though the respiratory and gastrointestinal organs may seem very different, there are some key similarities. A particularly interesting similarity is the presence of the ACE2 receptor, the receptor through which the COVID-19 causing SARS-CoV-2 virus can enter the cells. The inside of the intestine is loaded with ACE2 receptors. However, until now it was unknown whether intestinal cells could actually get infected and produce virus particles.

Intestinal organoids

COVID-19 intestine
Intestinal organoid infected with coronavirus SARS-CoV-2. The coronavirus is colored white, the organoids themselves are colored blue and green. Credits: Joep Beumer, copyright: Hubrecht Institute

Researchers from the Hubrecht Institute, Erasmus MC and Maastricht University set out to determine whether the SARS-CoV-2 virus can directly infect the cells of the intestine, and if so, whether it can replicate there as well. They used human intestinal organoids: tiny versions of the human intestine that can be grown in the lab. Hans Clevers (Hubrecht Institute): “These organoids contain the cells of the human intestinal lining, making them a compelling model to investigate infection by SARS-CoV-2.”

Infection of intestinal cells

Illustration of a villus in the intestine with a zoom-in to an electron microscopy image of coronavirus SARS-CoV-2 (dark circles) at the edge of an intestinal cell. Credits: Credit: Kèvin Knoops, Raimond Ravelli and Maaike de Backer, copyright: Maastricht University

When the researchers added the virus to the organoids, they were rapidly infected. The virus enters a subset of the cells in the intestinal organoids, and the number of cells that are infected increases over time. Using electron microscopy, an advanced way to visualize different components of the cell in great detail, the researchers found virus particles inside and outside the cells of the organoids. Peter Peters (Maastricht University): “Due to the lockdown, we all studied virtual slides of the infected organoids remotely from home.”

COVID-19 intestine
Intestinal organoids, the right one infected with coronavirus SARS-CoV-2. The coronavirus is colored white, the organoids themselves are colored blue and green. Credits Joep Beumer, copyright Hubrecht Institute

The researchers investigated the response of the intestinal cells to the virus with RNA sequencing, a method to study which genes are active in the cells. This revealed that so-called interferon stimulated genes are activated. These genes are known to combat viral infection. Future work will focus on these genes more carefully, and on how they could be used to develop new treatments.

The researchers also cultured the organoids in different conditions that result in cells with higher and lower levels of the ACE2 receptor, through which SARS-CoV-2 can enter the cells. To their surprise, they found that the virus infected cells with both high and low levels of the ACE2 receptor. Ultimately, these studies may lead to new ways to block the entry of the virus into our cells.

Implications

Bart Haagmans (Erasmus MC): “The observations made in this study provide definite proof that SARS-CoV-2 can multiply in cells of the gastrointestinal tract. However, we don’t yet know whether SARS-CoV-2, present in the intestines of COVID-19 patients, plays a significant role in transmission. Our findings indicate that we should look into this possibility more closely.” The current study is in line with other recent studies that identified gastrointestinal symptoms in a large fraction of COVID-19 patients and virus in the stool of patients free of respiratory symptoms. Special attention may be needed for those patients with gastrointestinal symptoms. More extensive testing using not only nose and throat swabs, but also rectal swabs or stool samples may thus be needed.

In the meantime, the researchers are continuing their collaboration to learn more about COVID-19. They are studying the differences between infections in the lung and the intestine by comparing lung and intestinal organoids infected with SARS-CoV-2.

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Publication

SARS-CoV-2 productively Infects Human Gut Enterocytes. Mart M. Lamers*, Joep Beumer*, Jelte van der Vaart*, Kèvin Knoops, Jens Puschhof, Tim I. Breugem, Raimond B.G. Ravelli, J. Paul van Schayck, Anna Z. Mykytyn, Hans Q. Duimel, Elly van Donselaar, Samra Riesebosch, Helma J.H. Kuijpers, Debby Schipper, Willine J. van de Wetering, Miranda de Graaf, Marion Koopmans, Edwin Cuppen, Peter J. Peters, Bart L. Haagmans† and Hans Clevers†. Science 2020. DOI * Equal contribution, † equal contribution.

This study was a collaboration between the Hubrecht Institute in Utrecht, the Erasmus MC University Medical Center Rotterdam, Maastricht University, the UMC Utrecht and Single Cell Discoveries in the Netherlands. The microscopy data are publicly available via the Image Data Resource (idr0083, https://idr.openmicroscopy.org – with help from the University of Dundee and the European Bioinformatics Institute) and the genomic data are publicly available via the Gene Expression Omnibus (GSE149312, https://www.ncbi.nlm.nih.gov/geo), to ensure efficient sharing of data related to COVID-19 between researchers all across the world.