Tag Archives: #temperature

Squirrels Help Scientists Understand How We Sense Heat (Biology)

The first complete high-res image of a heat-sensing molecule in ground squirrels is helping researchers understand how we sense temperature and could lead to the development of new pain relievers.

Ground squirrels, like other mammals, sense environmental temperatures with molecules called TRPV1 receptors that dot the surface of sensory nerves.

Cryo-EM map of the TRPV1 receptor. From Nadezhdin et al. (2021)

But unlike most mammals, ground squirrels love the heat. Ground squirrels—which look like a cross between a prairie dog and a chipmunk—thrive in hot climates, partly because their TRPV1 receptors are not activated by extreme heat. Even at temperatures of 115 F (46 C) degrees, ground squirrels are content, and their TRPV1 receptors remain unmoved.

“Understanding how the ground squirrel TRPV1 senses heat could also provide clues to how human TRPV1s sense heat, which is also not understood,” says Alexander Sobolevsky, PhD(link is external and opens in a new window), associate professor of biochemistry & molecular biophysics at Columbia University Vagelos College of Physicians and Surgeons, who led the imaging study.

To obtain images, the researchers first synthesized ground squirrel TRPV1 molecules in the lab and then put them under an electron microscope, using cryo-EM techniques pioneered by Columbia Nobel laureate Joachim Frank, PhD, professor of biochemistry & molecular biophysics.

The new images are the first of a full-size TRPV1 and they reveal that the receptor’s cap—which previous studies had failed to capture—plays an essential role in temperature detection. 

TRPV1 not only senses physical heat, it also detects the spicy heat of chili peppers but by a different mechanism. The researchers captured images of capsaicin, the molecule behind the heat, bound to TRPV1, which show that the molecule displaces an essential lipid in the cellular membrane that is also thought to be involved in sensing high temperatures. More research will be needed to fully understand how TRPV1 is activated by heat, capsaicin, and other molecules.

New images of the TRPV1 receptor are starting to reveal how the molecule senses both hot temperatures and the heat of chili peppers (via the pepper’s capsaicin). The cap plays an important role in temperature sensing, but capsaicin activates the receptor through a different mechanism. Image from Alexander Sobolevsky. 

TRPV1 receptors are also involved in pain, and additional images should also help in the design of new pain relievers that target TRPV1. TRPV1 receptors also have been found outside the sensory system and are being investigated as treatments for inflammatory bowel disease, cancer, and other conditions. 

“The new details we’re getting from the complete image of TRPV1 are telling us how the molecule works,” says Kirill Nadezhdin, a postdoctoral fellow in Sobolevsky’s lab and first author of the paper, “which is information that can help in the design of new treatments.”

More information

The study, titled “Extracellular cap domain is an essential component of the TRPV1 gating mechanism(link is external and opens in a new window),” was published April 12, 2021, in Nature Communications.

The authors: Kirill D. Nadezhdin (Columbia University), Arthur Neuberger (Columbia University), Yury A. Nikolaev (Yale University), Lyle A. Murphy (Yale University), Elena O. Gracheva (Yale University), Sviatoslav N. Bagriantsev (Yale University), and Alexander I. Sobolevsky (Columbia University).

The research was supported by the U.S. National Institutes of Health (grants 1R01NS091300, 1R01NS097547, R01CA206573, R01NS083660, and R01NS107253), and the U.S. National Science Foundation (grants 1754286, 1923127, and 1818086). 

The work was performed at the Columbia University Cryo-Electron Microscopy Center, the National Center for CryoEM Access and Training (NCCAT), and the Simons Electron Microscopy Center located at the New York Structural Biology Center, supported by the NIH Common Fund Transformative High-Resolution Cryo-Electron Microscopy program (U24 GM129539), and by grants from the Simons Foundation (SF349247) and the New York State Assembly.

Provided by Columbia University Irving Medical Center

Farm-Level Study Shows Rising Temperatures Hurt Rice Yields (Agriculture)

 temperature and yields of various rice varieties, based on 50 years of weather and rice-yield data from farms in the Philippines, suggests that warming temperatures negatively affect rice yields.

Recent varieties of rice, bred for environmental stresses like heat, showed better yields than both traditional rice varieties and modern varieties of rice that were not specifically bred to withstand warmer temperatures. But the study found that warming adversely affected crop yields even for those varieties best suited to the heat. Overall, the advantage of varieties bred to withstand increased heat was too small to be statistically significant.

One of the top 10 countries globally in rice production, the Philippines is also a top 10 rice importer, as domestic supply cannot meet demand.

Roderick Rejesus, a professor and extension specialist of agricultural and resource economics at North Carolina State University and the corresponding author of a paper that describes the study, says that teasing out the effects of temperature on rice yields is important to understand whether rice-breeding efforts have helped address the environmental challenges faced by modern society, such as global warming.

The study examined rice yields and atmospheric conditions from 1966 to 2016 in Central Luzon, the major rice-growing region of the Philippines. Rejesus and study colleagues were able to utilize farm-level data of rice yields and area weather conditions in four-to-five-year increments over the 50-year period, a rare data trove that allowed the researchers to painstakingly examine the relationship between rice yield and temperature in actual farm environments.

“This rich data set allowed us to see what was actually happening at the farm level, rather than only observing behavior at higher levels of aggregation like in provinces or districts,” Rejesus said.

The study examined three general rice varieties planted during those 50 years: traditional rice varieties; “early modern varieties” planted after the onset of the Green Revolution, which were bred for higher yields; and “recent modern varieties” bred for particular characteristics, like heat or pest resistance, for example.

Perhaps as expected, the study showed that, in the presence of warming, recent modern varieties had the best yields when compared with the early modern and traditional varieties, and that early modern varieties outperformed traditional varieties. Interestingly, some of the early modern varieties may have also mitigated heat challenges given their smaller “semi-dwarf” plant architecture, even though they were not bred to specifically resist heat.

“Taken all together, there are two main implications here,” Rejesus said. “The first is that, at the farm level, there appears to be a ‘yield gap’ between how rice performs in breeding trials and on farms, with farm performance of recent varieties bred to be more tolerant to environmental stresses not being statistically different relative to the older varieties.

“The second is that rice breeding efforts may not have reached their full potential such that it may be possible to produce new varieties that will statistically perform better than older varieties in a farm setting.”

Rejesus also acknowledged that the study’s modest sample size may have contributed to the inability to find statistical significance in the differences in warming impacts between rice varietal yields.

“This paper has implications for other rice-breeding countries, like Vietnam, because the timing of the release of various rice varieties is somewhat similar to that of the Philippines,” Rejesus said. “Plant-breeding institutions can learn from this type of analysis, too. It provides guidance as to where research funding may be allocated by policymakers to further improve the high temperature tolerance of rice varieties available to farmers.”

Rejesus plans to further study other agricultural practices and innovations that affect crop yields, including an examination of cover crops, or plants grown on cropland in the off season that aim to keep soils healthy, to gauge whether they can mitigate the adverse impacts of a changing climate.

The paper appears in the American Journal of Agricultural Economics. Former NC State Ph.D. student Ruixue Wang is the paper’s first author. Jesse B. Tack from Kansas State University, Joseph V. Balagtas of Purdue University and Andy D. Nelson of the University of Twente are other paper co-authors. Support for the work was provided in part by the U.S. Department of Agriculture’s NIFA Hatch Project No. NC02696.

Featured image: Study shows effects of warming on rice yields. “Rice!” by Simoubuntu is licensed with CC BY-SA 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-sa/2.0/

Reference: Ruixue Wang and Roderick Rejesus, Jesse B. Tack, Joseph V. Balagtas, and Andy D. Nelson, “Quantifying the Yield Sensitivity of Modern Rice Varieties to Warming Temperatures: Evidence from the Philippines“, American Journal of Agricultural Economics, March 4, 2021. DOI: 10.1111/ajae.12210

Provided by NC State University

Secret to How Cholera Adapts to Temperature Revealed (Biology)

A protein that helps Vibrio cholerae adapt to temperature has been identified, providing insights into how bacteria change their biology under different conditions.

Scientists have discovered an essential protein in cholera-causing bacteria that allows them to adapt to changes in temperature, according to a study published today in eLife.

The protein, BipA, is conserved across bacterial species, which suggests it could hold the key to how other types of bacteria change their biology and growth to survive at suboptimal temperatures.

Vibrio cholerae (V. cholerae) is the bacteria responsible for the severe diarrhoeal disease cholera. As with other species, V. cholerae forms biofilms – communities of bacteria enclosed in a structure made up of sugars and proteins – to protect against predators and stress conditions. V. cholerae forms these biofilms both in their aquatic environment and in the human intestine. There is evidence to suggest that biofilm formation is crucial to V. cholerae’s ability to colonise in the intestine and might enhance its infectivity.

V. cholerae experiences a wide range of temperatures, and adapting to them is not only important for survival in the environment but also for the infection process,” explains lead author Teresa del Peso Santos, a postdoctoral researcher at the Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Sweden. “We know that at 37 degrees Celsius, V. cholerae grows as rough colonies that form a biofilm. However, at lower temperatures these colonies are completely smooth. We wanted to understand how it does this.”

The researchers screened the microbes for genes known to be linked with biofilm formation. They found a marked increase in the expression of biofilm-related genes in colonies grown at 37C compared with 22C.

To find out how these biofilm genes are controlled at lower temperatures, they generated random mutations in V. cholerae and then identified which mutants developed rough instead of smooth colonies at 22C. They then isolated the colonies to determine which genes are essential for switching off biofilm genes at low temperatures.

The most common gene they found is associated with a protein called BipA. As anticipated, when they intentionally deleted BipA from V. cholerae, the resulting microbes formed rough colonies typical of biofilms rather than smooth colonies. This confirmed BipA’s role in controlling biofilm formation at lower temperatures.

To explore how BipA achieves this, the researchers compared the proteins produced by normal V. cholerae with those produced by microbes lacking BipA, at 22 and 37 degrees Celsius. They found that BipA alters the levels of more than 300 proteins in V. cholerae grown at suboptimal temperatures, increasing the levels of 250 proteins including virtually all known biofilm-related proteins. They also showed that at 37 degrees Celsius, BipA adopts a conformation that may make it more likely to be degraded. In BipA’s absence, the production of key biofilm regulatory proteins increases, leading to the expression of genes responsible for biofilm formation.

These results provide new insights into how V. cholerae adapts to temperature and will help understand – and ideally prevent – its survival in different environments and transmission into humans.

“We have shown that BipA is critical for temperature-dependent changes in the production of biofilm components and alters colony shape in some V. cholerae strains,” concludes senior author Felipe Cava, Associate Professor at the Department of Molecular Biology, and MIMS Group Leader and Wallenberg Academy Fellow, Umeå University. “Future research will address the effect of temperature- and BipA-dependent regulation on V. cholerae during host infection and the consequences for cholera transmission and outbreaks.”

Featured image: This image shows a smooth colony of Vibrio cholerae (left) next to a rough colony formed at 37C (right). Image credit: Santos et al. (CC BY 4.0)

Reference: Teresa del Peso Santos et al., “BipA exerts temperature-dependent translational control of biofilm-associated colony morphology in Vibrio cholerae”, Microbiology and Infectious Disease, 2021. https://elifesciences.org/articles/60607

Provided by Elife

Researchers Find Why ‘Lab-made’ Proteins Have Unusually High Temperature Stability (Chemistry)

Bioengineers have found why proteins that are designed from scratch tend to be more tolerant to high temperatures than proteins found in nature.

Structure of the de novo protein with most of the core filled with valine residues (green). Ten hydrophobic residues were mutated to smaller valine residues. This de novo protein still shows high thermal stability above 100 ºC. ©NINS/IMS

Natural proteins with high ‘thermostability’ are prized for their wide range of applications, from baking and paper-making to chemical production. Efforts to enhance protein thermostability–and to discover the principles behind this–is one of the hottest topics in biotech.

The latest discoveries, described in the Proceedings of the National Academy of Sciences on November 23, 2020, open up the possibility of lab-made proteins with even better industrial applicability.

Researchers in the relatively young field of protein design have attempted to come up with new types of proteins for myriad medical, pharmaceutical and industrial applications. Until recently, protein engineers have focused on manipulating existing natural proteins. However, these natural proteins are difficult to alter without also distorting the general functioning of the protein–much like adding a fifth wheel to a car.

To avoid this, some protein engineers have begun to build novel proteins entirely from scratch, or what is called de novo protein design.

However, this quest has its own set of issues. For example, building proteins from scratch is much harder computationally, and requires a complete understanding of the principles of protein folding–the multiple levels of how a protein literally folds itself into a particular structure.

In biology, structure determines function, much like how a key fits into a keyhole or a cog into a sprocket. The shape of a biological entity is what allows it to do its job within an organism. And upon their production by cells, proteins just fall into their shape, simply as a result of physical laws.

But the principles that govern the interaction of these physical laws during the folding process are frustratingly complex–hence the computational difficulty. They are also still largely unknown. This is why a great deal of effort in protein engineering in recent years has focused on attempting to discover these protein design principles that emerge from physical laws.

And one of the mysteries facing protein designers has been the high thermostability of these ‘lab-made’ proteins.

“For some reason, de novo proteins have repeatedly shown increased tolerance in the face of quite high temperatures compared to natural proteins,” said Nobuyasu Koga, associate professor at Institute for Molecular Science, and an author of the study. “Where others would ‘denature’, the lab-made proteins are still working just fine well above 100 ºC.”

The design principles that have been discovered so far emphasize the importance of the backbone structure of proteins–the chain of nitrogen, carbon, oxygen and hydrogen atoms.

On the other hand, these principles have also held that the tight packing of the fatty, hydrophobic (water-resistant) core of naturally occurring proteins–or rather the molecular interactions that allow them to sit together as snugly as pieces of a jigsaw puzzle–is the dominant force that drives protein folding. Just as how oil and water don’t mix, the fattier part of the protein when surrounded by water will naturally pull itself together without any need for an external ‘push’.

“Indeed, according to our design principles, protein cores were engineered specifically to be as tightly packed and as fatty as possible,” Nobuyasu Koga said. “So the question was: Which is more important for high thermostability, backbone structure or the fat and tight core packing?”

So the researchers took the de novo proteins they had designed that had shown the highest thermal stability, and began to tweak them with ten amino acids involved with the hydrophobic core packing. As they did this, they saw still folding ability and little reduction in overall thermal stability, suggesting that it is instead the backbone structure, not the hydrophobic core packing, that contributes the most to high thermostability. “It is surprising that the protein can fold with high thermal stability, even the loose core packing,” said Naohiro Kobayashi, coauthor and a senior research fellow at RIKEN.

“Hydrophobic tight core packing may not even be very important for designed proteins,” added Rie Koga, coauthor and a researcher at Exploratory Research Center on Life and Living Systems (ExCELLS). “We can create an exceptionally stable protein even if the core packing is not so optimized.”

The next step for the researchers is to further develop rational principles for protein design, especially with respect to what extent that substructures of the backbone, especially loops within it, can be altered without endangering its folding ability and high thermostability.

Reference: Rie Koga, Mami Yamamoto, Takahiro Kosugi, Naohiro Kobayashi, Toshihiko Sugiki, Toshimichi Fujiwara, Nobuyasu Koga, “Robust folding of a de novo designed ideal protein even with most of the core mutated to valine”, Proceedings of the National Academy of Sciences Dec 2020, 117 (49) 31149-31156; https://www.pnas.org/content/117/49/31149 DOI: 10.1073/pnas.2002120117

Provided by National Institute of Natural Science

Research Identifies Earth’s Extreme Environments as Best Places for Life to Grow (Biology)

A faculty member from The University of Texas at El Paso (UTEP) is at the forefront of research that is shaping new realities about the potential for new organisms to thrive in seemingly harsh, desolate areas of the planet.

The paper “The evolution of a tropical biodiversity hotspot” led by Michael Harvey, Ph.D., assistant professor of biological sciences at UTEP and Gustavo Bravo, Ph.D., research associate at the Museum of Comparative Zoology at Harvard University was published in the research journal “Science.” The paper introduces the paradox of diversity – the concept that new species form away from tropical diversity hotspots. ©Michael Harvey

A report published Dec. 11, 2020, in the research journal Science dispels the premise that areas such as the Amazon rainforest are biodiversity hotspots because new species tend to evolve there. A multinational team of scientists, who conducted their research in a major group of tropical birds, found that new species are actually less likely to form in these hotspots than coldspots — places such as deserts and mountaintops that do not have a lot of species but do have a lot of opportunity.

The paper titled “The evolution of a tropical biodiversity hotspot” introduces the paradox of diversity – the concept that new species form away from tropical diversity hotspots. Researchers led by Michael Harvey, Ph.D., assistant professor of biological sciences and curator of the biodiversity collections at UTEP, and Gustavo Bravo, Ph.D., research associate at the Museum of Comparative Zoology at Harvard University, discovered that coldspots may be extreme with dry, unstable environments but are relatively empty, giving new species room to evolve. In contrast, hotspots such as the Amazon are the result of the gradual accumulation of species over a long period of time.

“Exciting studies like these just reinforce how interconnected our world is, not just its plants and animals, but our science and the researchers that change our perception of this planet and make these tremendous findings possible,” said Robert Kirken, Ph.D., dean of UTEP’s College of Science.

This paradox was revealed through decades-long work by dozens of natural history museums and museum researchers who studied 2,400 genes isolated from 1,300 species to document the rapidly disappearing diversity of the tropics. Robb Brumfield, director of the Louisiana State University (LSU) Museum of Natural History in Baton Rouge and one of the senior authors of the paper, indicated that conservation efforts to save the rapidly changing tropical landscape need to focus not only on the species-rich Amazon but also the generators of that diversity, like the wind-swept, cold puna of the Andes Mountains.

Harvey and Bravo spent months preserving samples up remote streams in Amazonia and rugged mountain ranges in the Andes. Bravo said they were only able to make their discovery due to the hard work of numerous local scientists who dedicated their lives to studying and preserving this diversity.

“These birds represent an incredible amount of diversity sampled, roughly one out of every three species of birds in the American tropics,” Harvey said.

Notably, the study’s collection trips and research teams are increasingly led by ornithologists from groups underrepresented in the sciences, including Latinx and women researchers. Many of the researchers involved in the study are from Latin America (Colombia, Brazil, Uruguay and Venezuela) and recent teams fielded by the LSU Museum of Natural Science to obtain samples like those used in this study have been women-led efforts.

“This paper marks not only a change in our understanding of evolution in the tropics but also an acknowledgement and valuation of the diversity of culture, expertise, and perspective in the field of ornithology,” said Liz Derryberry, Ph.D., associate professor of ecology and evolutionary biology at the University of Tennessee, Knoxville and a senior author of the paper.

Reference: Michael G. Harvey, Gustavo A. Bravo, Santiago Claramunt, Andrés M. Cuervo, Graham E. Derryberry, Jaqueline Battilana, Glenn F. Seeholzer, Jessica Shearer McKay, Brian C. O’Meara, Brant C. Faircloth, Scott V. Edwards, Jorge Pérez-Emán, Robert G. Moyle, Frederick H. Sheldon, Alexandre Aleixo, Brian Tilston Smith, R. Terry Chesser, Luís Fábio Silveira, Joel Cracraft, Robb T. Brumfield, Elizabeth P. Derryberry, “The evolution of a tropical biodiversity hotspot”, Science 11 Dec 2020: Vol. 370, Issue 6522, pp. 1343-1348 DOI: 10.1126/science.aaz6970 https://science.sciencemag.org/content/370/6522/1343

Provided by University of Texas at El Paso

In A Warming Climate, Can Birds Take The Heat? (Biology)

We don’t know precisely how hot things will get as climate change marches on, but there’s reason to believe animals in the tropics may not fare as well as their temperate relatives. Many scientists think tropical animals, because they’re accustomed to a more stable thermal environment, may be pushed beyond their limits quickly as temperatures soar. And that could lead to massive species loss.

In a new University of Illinois study, tropical birds such as the cocoa woodcreeper (pictured) showed less acute heat stress when exposed to high temperatures than expected. ©Henry Pollock, University of Illinois

Yet, in a first-of-its-kind study, University of Illinois researchers show both temperate and tropical birds can handle acute heat stress much better than expected.

“In terms of their thermal physiology, a lot of these birds, including tropical species, can tolerate temperatures that are a lot higher than what they experience in their daily lives. That was surprising because tropical ectotherms, such as insects, have been shown to be extremely vulnerable to climate warming,” says Henry Pollock, postdoctoral researcher at Illinois and first author on the study. “We’re just not seeing the same things in birds. It is somewhat encouraging.”

Although they observed some promising trends, the researchers caution against celebrating too soon.

“It’s not necessarily comforting news. If someone walked away from this thinking tropical birds are going to do fine because they’re not going to overheat, that would be a simplistic bottom line to take away from this paper,” says Jeff Brawn, professor in the Department of Natural Resources and Environmental Sciences at Illinois and co-author on the study. “Warming is likely to affect tropical birds indirectly, by impacting their resources, the structure of tropical forests. So they may not be flying around panting, suffering from heat exhaustion, but there may be more indirect effects.”

To test the assumption that tropical and temperate birds differ in their ability to cope with heat stress, Pollock brought 81 species from Panama and South Carolina into field labs to test their responses to rising temperatures. Using tiny sensors, he was able to detect internal body temperatures, as well as metabolic rates, when he exposed the birds to warmer and warmer environments.

Species from both temperate and tropical zones handled the rising temperatures just fine. Birds from South Carolina had a higher heat tolerance, on average, than Panamanian birds, but both groups exceeded Pollock and Brawn’s expectations. And among all the birds, doves and pigeons emerged as thermal superstars. Most birds cool down by panting, but doves and pigeons take advantage of their unique-among-birds ability to “sweat.” In fact, Pollock says, they exceeded the limits of his testing equipment.

Although the study provided the first-ever heat tolerance data for many bird species, the results take on more meaning when put into the context of warming projections.

“Both temperate and tropical birds were able to tolerate temperatures into the 40s [in degrees Celsius], but they only experience maximum temperatures of around 30 degrees Celsius in their everyday environments, so they have a substantial buffer,” Pollock says.

In other words, even if maximum air temperatures rise 3 to 4 degrees Celsius, as projected by some scientists, that’s well within the thermal safety margins of all the birds Pollock measured.

It’s important to note the experiment, which measured acute heat stress, doesn’t exactly replicate what’s projected to happen during much more gradual climate warming. But few studies have examined the effects of chronic heat stress in birds, and having this baseline knowledge of their acute physiological limits is a good start.

“This is the first geographic comparison ever for birds. We need more data from more sites and studies of chronic heat stress over longer periods of time. But I think at the very least, what we can say is that they’re able to tolerate higher temperatures than I think anybody expected,” Pollock says.

Brawn adds, “We’re just starting to scratch the surface of what we need to do to really understand how climate change is going to affect birds. But this is an important first step.”

References: Henry Pollock, Jeff Brawn, and Zachary Cheviron, “Heat tolerances of temperate and tropical birds and their implications for susceptibility to climate warming,” is published in Functional Ecology [DOI: 10.1111/1365-2435.13693]. http://dx.doi.org/10.1111/1365-2435.13693

Provided by University of Illinois

The Universe Is Getting Hot, Hot, Hot, A New Study Suggests (Astronomy)

Temperature has increased about 10 times over the last 10 billion years.

The universe is getting hotter, a new study has found.

The study, published Oct. 13 in the Astrophysical Journal, probed the thermal history of the universe over the last 10 billion years. It found that the mean temperature of gas across the universe has increased more than 10 times over that time period and reached about 2 million degrees Kelvin today — approximately 4 million degrees Fahrenheit.

A new study has found that the universe is getting hotter. Credit: Greg Rakozy on Unsplash.

“Our new measurement provides a direct confirmation of the seminal work by Jim Peebles — the 2019 Nobel Laureate in Physics — who laid out the theory of how the large-scale structure forms in the universe,” said Yi-Kuan Chiang, lead author of the study and a research fellow at The Ohio State University Center for Cosmology and AstroParticle Physics.

The large-scale structure of the universe refers to the global patterns of galaxies and galaxy clusters on scales beyond individual galaxies. It is formed by the gravitational collapse of dark matter and gas.

“As the universe evolves, gravity pulls dark matter and gas in space together into galaxies and clusters of galaxies,” Chiang said. “The drag is violent — so violent that more and more gas is shocked and heated up.”

The findings, Chiang said, showed scientists how to clock the progress of cosmic structure formation by “checking the temperature” of the universe.

The researchers used a new method that allowed them to estimate the temperature of gas farther away from Earth — which means further back in time — and compare them to gases closer to Earth and near the present time. Now, he said, researchers have confirmed that the universe is getting hotter over time due to the gravitational collapse of cosmic structure, and the heating will likely continue.

To understand how the temperature of the universe has changed over time, researchers used data on light throughout space collected by two missions, Planck and the Sloan Digital Sky Survey. Planck is the European Space Agency mission that operates with heavy involvement from NASA; Sloan collects detailed images and light spectra from the universe.

As the universe evolves, matter concentrations are surrounded by gas halos getting hotter and bigger. (Credit: D. Nelson / Illustris Collaboration)

They combined data from the two missions and evaluated the distances of the hot gases near and far via measuring redshift, a notion that astrophysicists use to estimate the cosmic age at which distant objects are observed. (“Redshift” gets its name from the way wavelengths of light lengthen. The farther away something is in the universe, the longer its wavelength of light. Scientists who study the cosmos call that lengthening the redshift effect.)

The concept of redshift works because the light we see from objects farther away from Earth is older than the light we see from objects closer to Earth — the light from distant objects has traveled a longer journey to reach us. That fact, together with a method to estimate temperature from light, allowed the researchers to measure the mean temperature of gases in the early universe — gases that surround objects farther away — and compare that mean with the mean temperature of gases closer to Earth — gases today.

Those gases in the universe today, the researchers found, reach temperatures of about 2 million degrees Kelvin — approximately 4 million degrees Fahrenheit, around objects closer to Earth. That is about 10 times the temperature of the gases around objects farther away and further back in time.

The universe, Chiang said, is warming because of the natural process of galaxy and structure formation. It is unrelated to the warming on Earth. “These phenomena are happening on very different scales,” he said. “They are not at all connected.”

References : Chiang, Yi-Kuan; Makiya, Ryu; Ménard, Brice; Komatsu, Eiichiro, “The Cosmic Thermal History Probed by Sunyaev-Zeldovich Effect Tomography”, The Astrophysical Journal, Volume 902, Issue 1, id.56, 17 doi:10.3847/1538-4357/abb403 https://ui.adsabs.harvard.edu/abs/2020ApJ.902.56C/abstract

Provided by Ohio state University

High Temperatures Threaten The Survival of Insects (Biology)

Insects have difficulties handling the higher temperatures brought on by climate change, and might risk overheating. The ability to reproduce is also strongly affected by rising temperatures, even in northern areas of the world, according to a new study from Lund University in Sweden.

Insects cannot regulate their own body temperature, which is instead strongly influenced by the temperature in their immediate environment. In the current study, the researchers studied two closely related species of damselflies in Sweden. The goal was to understand their robustness and ability to tolerate changes in temperature.

To study this, the researchers used a combination of field work in southern Sweden and infrared camera technology (thermography), a technology that makes it possible to measure body temperature in natural conditions. This information was then connected to the survival rates and reproductive success of the damselflies in their natural populations.

The results show that survivorship of these damselflies was high at relatively low temperatures, 15 – 20 C °. The reproductive capacity, on the other hand, was higher at temperatures between 20 and 30 C °, depending on the species.

“There is therefore a temperature-dependent conflict between survival on one hand and the ability to reproduce on the other”, says Erik Svensson, professor at the Department of Biology at Lund University, who led the study.

The study also shows that the damselflies ability to handle heat-related stress is limited. Insects are cold-blooded invertebrates, so they rely on external sources such as the sun or hot stones to raise their body temperature.

“Our results show that cold-blooded animals can suffer from overheating even if they live far up in the northern hemisphere, and that their ability to buffer their body temperature against rising external temperatures is limited. The results also challenge a popular theory that animals’ plasticity, i. e. their individual flexibility, can help them survive under harsher environmental conditions, such as during heat waves”, says Erik Svensson.

Provided by Lund University

This Newly Developed Nanomaterial Can Act As A Precise Thermometer (Nanotechnology / Engineering)

A layered material developed by KAUST researchers can act as a precise temperature sensor by exploiting the same principle used in biological ion channels.

This SEM image shows an as-prepared lamellar membrane out of MXene before exposure to water/light/heat.© KAUST 2020

Human cells possess various proteins that act as channels for charged ions. In the skin, certain ion channels rely on heat to drive a flow of ions that generates electrical signals, which we use to sense the temperature of our surroundings.

Inspired by these biological sensors, KAUST researchers prepared a titanium carbide compound (Ti3C2Tx) known as an MXene, which contains multiple layers just a few atoms thick. Each layer is covered with negatively charged atoms, such as oxygen or fluorine. “These groups act as spacers to keep neighboring nanosheets apart, allowing water molecules to enter the interplanar channels,” says KAUST postdoc Seunghyun Hong, part of the team behind the new temperature sensor. The channels between the MXene layers are narrower than a single nanometer.

The researchers used techniques, such as X-ray diffraction and scanning electron microscopy, to investigate their MXene, and they found that adding water to the material slightly widened the channels between layers. When the material touched a solution of potassium chloride, these channels were large enough to allow positive potassium ions to move through the MXene, but blocked the passage of negative chloride ions.

A temperature difference between two ends of an MXene nanochannel causes water and potassium ions to flow from the cool side to the warm side (top). When sunlight heats just one part of an MXene device, a thermo-osmotic flow generates a voltage that can indicate tiny temperature changes (bottom). © 2020 ACS Nano; Alshareef, H.N. et al.

The team created a small device containing the MXene and exposed one end of it to sunlight. MXenes are particularly efficient at absorbing sunlight and converting that energy into heat. The resulting temperature rise prompted water molecules and potassium ions to flow through the nanochannels from the cooler end to the warmer part, an effect known as thermo-osmotic flow. This caused a voltage change comparable to that seen in biological temperature-sensing ion channels. As a result, the device could reliably sense temperature changes of less than one degree Celsius.

Decreasing the salinity of the potassium chloride solution improved the performance of the device, in part by further enhancing the channel’s selectivity for potassium ions.

As the researchers increased the intensity of light shining on the material, its temperature rose at the same rate, as did the ion-transporting response. This suggests that along with acting as a temperature sensor the material could also be used to measure light intensity.

The work was a result of collaboration between the groups of KAUST professors Husam Alshareef and Peng Wang. “We envision that the MXene cation channels have promise for many potential applications, including temperature sensing, photodetection or photothermoelectric energy harvesting,” says Alshareef, who co-led the team.

References: Hong, S., Zou, G., Kim, H., Huang, D., Wang, P. & Alshareef, H.N. Photothermoelectric response of Ti3C2Tx MXene confined ion channels. ACS Nano 14, 9042–9049 (2020). https://pubs.acs.org/doi/10.1021/acsnano.0c04099 doi: https://doi.org/10.1021/acsnano.0c04099

Provided by KAUST