It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Wednesday, February 15, 2023
UCalgary researchers develop new imaging technique for clearer picture of “brain in the gut”
New view of gut’s nervous system will lead to better understand of gastrointestinal disorders
University of Calgary researchers designed a novel imaging and experimental preparation system, allowing them to record the activity of the enteric nervous system in mice. The new technique allows researchers to record what is sometimes referred to as the gut’s brain during the complex processes of digestion and waste elimination.
“This completely different way of conducting experiments allows us to better understand the complexity of the nerve interactions that are regulating and coordinating the responses by the gut’s nervous system,” says Dr. Wallace MacNaughton, PhD, co-principal investigator. “It opens up new avenues for us to understand what’s really going on, and that’s going to help us understand gastrointestinal diseases and disorders a lot better.”
Neurons, or nerve cells, embedded in the wall of the gut precisely control its movements. The team used mice genetically encoded with fluorescent labels, so the neurons in the gut’s nervous system would “light up,” glowing green under microscopes, whenever the neurons were activated. The images are already providing new insights.
“This wave of excitation around the circumference of the gut, and the change in neuronal excitability, have never been seen before,” says Dr. Keith Sharkey, PhD, co-principal investigator. “When the gut is distended, the nerve circuits respond in ways that are totally different than when the gut is relaxed.”
The team’s study is the first that shows, in an intact gut preparation, the role of the gut’s physical distention in controlling how the entire neural network in the gut is coordinated. The findings published in the Journal of Physiology include instructions on how to replicate the technique which Sharkey describes as marrying technology with biology.
“We wanted all researchers to have access to this approach,” says Sharkey. “Gaining a better understanding of the physiology of the gut is fundamental to being able to understand what happens when it doesn’t work properly, and to developing effective treatments.”
The populations of neurons, the neural architecture, and the way the gut is arranged is virtually identical in the mouse gut and the human gut. This makes it highly likely that similar processes occur in the human gut, the researchers say.
Gastrointestinal (GI) disorders, such as irritable bowel syndrome and Crohn’s disease, impact 10 to 20 per cent of North America’s population and cost billions of dollars in health care. Yet because GI disorders are poorly understood, current treatments work for only a fraction of patients, may lose their effectiveness over time, or cause serious side effects.
Sharkey and MacNaughton now plan to investigate how probiotics, inflammation and bacterial infection alter the control and coordination of the gut’s nervous system in mice.
“This is giving us a model that may help us test new approaches to treating gastrointestinal diseases in people at some point in the future,” MacNaughton says.
The co-first authors on the study, Dr. Jean-Baptiste Cavin, PhD, and Dr. Preedajit Wongkrasant, PhD, were fundamental in designing the experimental system and refining the techniques.
IMAGE: ARTIST'S IMPRESSION OF A SUPERMASSIVE BLACK HOLE. COSMOLOGICAL COUPLING ALLOWS BLACK HOLES TO GROW IN MASS WITHOUT CONSUMING GAS OR STARS.view more
CREDIT: UH MĀNOA
Searching through existing data spanning 9 billion years, a team of researchers led by scientists at University of Hawaiʻi at Mānoa has uncovered the first evidence of "cosmological coupling" –a newly predicted phenomenon in Einstein's theory of gravity, possible only when black holes are placed inside an evolving universe.
Astrophysicists Duncan Farrah and Kevin Croker led this ambitious study, combining Hawaiʻi's expertise in galaxy evolution and gravity theory with the observation and analysis experience of researchers across nine countries to provide the first insight into what might exist inside real black holes.
"When LIGO heard the first pair of black holes merge in late 2015, everything changed," said Croker. "The signal was in excellent agreement with predictions on paper, but extending those predictions to millions, or billions of years? Matching that model of black holes to our expanding universe? It wasn't at all clear how to do that."
The first paper found that these black holes gain mass over billions of years in a way that can't easily be explained by standard galaxy and black hole processes, such as mergers or accretion of gas.
The second paper finds that the growth in mass of these black holes matches predictions for black holes that not only cosmologically couple, but also enclose vacuum energy—material that results from squeezing matter as much as possible without breaking Einstein's equations, thus avoiding a singularity.
With singularities absent, the paper then shows that the combined vacuum energy of black holes produced in the deaths of the universe's first stars agrees with the measured quantity of dark energy in our universe.
“We're really saying two things at once: that there's evidence the typical black hole solutions don't work for you on a long, long timescale, and we have the first proposed astrophysical source for dark energy,'' said Farrah, lead author of both papers.
“What that means, though, is not that other people haven't proposed sources for dark energy, but this is the first observational paper where we're not adding anything new to the universe as a source for dark energy: black holes in Einstein's theory of gravity are the dark energy.''
These new measurements, if supported by further evidence, will redefine our understanding of what a black hole is.
Nine billion years ago In the first study, the team determined how to use existing measurements of black holes to search for cosmological coupling.
"My interest in this project was really born from a general interest in trying to determine observational evidence that supports a model for black holes that works regardless of how long you look at them," Farrah said. "That's a very, very difficult thing to do in general, because black holes are incredibly small, they're incredibly difficult to observe directly, and they are a long, long way away."
Black holes are also hard to observe over long timescales. Observations can be made over a few seconds, or tens of years at most—not enough time to detect how a black hole might change throughout the lifetime of the universe. To see how black holes change over a scale of billions of years is a bigger task.
"You would have to identify a population of black holes and identify their distribution of mass billions of years ago. Then you would have to see the same population, or an ancestrally connected population, at present day and again be able to measure their mass," said co-author Gregory Tarlé, a physicist at University of Michigan. "That's a really difficult thing to do."
Because galaxies can have life spans of billions of years, and most galaxies contain a supermassive black hole, the team realized that galaxies held the key, but choosing the right types of galaxy was essential.
"There were many different behaviors for black holes in galaxies measured in the literature, and there wasn't really any consensus," said study co-author Sara Petty, a galaxy expert at NorthWest Research Associates. "We decided that by focusing only on black holes in passively evolving elliptical galaxies, we could help to sort this thing out."
Elliptical galaxies are enormous and formed early. They are fossils of galaxy assembly. Astronomers believe them to be the final result of galaxy collisions, enormous in size with upwards of trillions of old stars.
By looking at only elliptical galaxies with no recent activity, the team could argue that any changes in the galaxies' black hole masses couldn't easily be caused by other known processes. Using these populations, the team then examined how the mass of their central black holes changed throughout the past 9 billion years.
If mass growth of black holes only occurred through accretion or merger, then the masses of these black holes would not be expected to change much at all. However if black holes gain mass by coupling to the expanding universe, then these passively evolving elliptical galaxies might reveal this phenomenon.
The researchers found that the further back in time they looked, the smaller the black holes were in mass, relative to their masses today. These changes were big: The black holes were anywhere from 7 to 20 times larger today than they were 9 billion years ago—big enough that the researchers suspected cosmological coupling could be the culprit.
Unlocking black holes
In the second study, the team investigated whether the growth in black holes measured in the first study could be explained by cosmological coupling alone.
"Here's a toy analogy. You can think of a coupled black hole like a rubber band, being stretched along with the universe as it expands," said Croker. "As it stretches, its energy increases. Einstein's E = mc2tells you that mass and energy are proportional, so the black hole mass increases, too."
How much the mass increases depends on the coupling strength, a variable the researchers call k.
"The stiffer the rubber band, the harder it is to stretch, so the more energy when stretched. In a nutshell, that's k," Croker said.
Because mass growth of black holes from cosmological coupling depends on the size of the universe, and the universe was smaller in the past, the black holes in the first study must be less massive by the correct amount in order for the cosmological coupling explanation to work.
The team examined five different black hole populations in three different collections of elliptical galaxies, taken from when the universe was roughly one half and one third of its present size. In each comparison, they measured that k was nearly positive 3.
The first observational link
In 2019, this value was predicted for black holes that contain vacuum energy, instead of a singularity by Croker, then a graduate student, and Joel Weiner, a UH Mānoa mathematics professor.
The conclusion is profound: Croker and Weiner had already shown that if k is 3, then all black holes in the universe collectively contribute a nearly constant dark energy density, just like measurements of dark energy suggest.
Black holes come from dead large stars, so if you know how many large stars you are making, you can estimate how many black holes you are making and how much they grow as a result of cosmological coupling. The team used the very latest measurements of the rate of earliest star formation provided by the James Webb Space Telescope and found that the numbers line up.
According to the researchers, their studies provide a framework for theoretical physicists and astronomers to further test—and for the current generation of dark energy experiments such as the Dark Energy Spectroscopic Instrument and the Dark Energy Survey—to shed light on the idea.
"If confirmed this would be a remarkable result, pointing the way towards the next generation of black hole solutions," said Farrah.
Croker added, "This measurement, explaining why the universe is accelerating now, gives a beautiful glimpse into the real strength of Einstein's gravity. A chorus of tiny voices spread throughout the universe can work together to steer the entire cosmos. How cool is that?"
Researchers studied elliptical galaxies like Messier 59 to determine if the mass of their central black holes changed throughout the past 9 billion years. The smooth distribution of light is billions of stars.
CREDIT
ESA/Hubble & NASA, P. Cote
Caldwell 53 (NGC 3115) is most notable for the supermassive black hole that can be found at its center.
CREDIT
NASA, ESA, and J. Erwin (University of Alabama)
Measurement of coupling strength k by comparing black hole masses in 5 different collections of ancient elliptical galaxies to the black holes in elliptical galaxies today. Measurements cluster around k = 3, implying that black holes contain vacuum energy, instead of a singularity.
IMAGE: TWO JAGUARS, CAUGHT WITH A CAMERA TRAP SURVEY, WALK THROUGH THE BRAZILIAN AMAZON RAINFOREST.view more
CREDIT: DANIEL ROCHA/UC DAVIS
From jaguars and ocelots to anteaters and capybara, most land-based mammals living in the Brazilian Amazon are threatened by climate change and the projected savannization of the region. That’s according to a study published in the journal Animal Conservation by the University of California, Davis.
The study found that even animals that use both forest and savanna habitats, such as pumas and giant armadillos, are vulnerable to such changes. It also illustrates how species and lands protected through local conservation efforts are not immune to global climate change.
“We’re losing Amazon forest as we speak,” said lead author Daniel Rocha, who conducted the research as a doctoral student in the UC Davis Department of Wildlife, Fish and Conservation Biology. “The Amazon’s biodiversity is very susceptible to climate change effects. It’s not just local; it’s a global phenomenon. We cannot stop this just by law enforcement, for example. These species are more susceptible than we realized, and even protected areas can’t protect them as much as we thought.”
What is ‘savannization?’
Pristine savanna is a unique biome that supports a diverse array of life. But “savannization” here refers to when lush rainforest gives way to a drier, open landscape that resembles savanna but is actually degraded forest. Local deforestation and global climate changes in temperature and precipitation favor this conversion along the southern and eastern edges of the Brazilian Amazon.
Arboreal species like monkeys clearly will be impacted by such changes. But the study’s authors wanted to better understand how land-based mammals are expected to fare — especially those who use both forest and savanna habitats when they have access to both.
Caught on camera
For the study, the researchers conducted camera trap surveys of land-based mammals in four protected areas of the southern Brazilian Amazon, which is a mixture of rainforest and natural Cerrado, or savanna. Using statistical models, they quantified how 31 species were affected by savanna habitat. They then looked for differences among species known to use mostly rainforest, savanna, or both habitats.
The results showed that only a few species preferred savanna habitat. Rocha notes that the models were based on pristine — not degraded — savanna, so the negative effects of savannization among animals will likely be even stronger.
Riparian forests, which line the wet edges of rivers and streams, helped buffer the effects of savannization to some extent.
Winners and losers
“Unfortunately, there are more losers than winners,” said Rocha, who is currently an assistant professor at Southern Nazarene University in Oklahoma. “Most Amazon species, when they can choose between good forests and good savanna, they choose the forest. That’s true even for species considered ‘generalists,’ which use both habitats. As we lose forests, they suffer, too.”
The results indicate that if climate-driven savannization causes species to lose access to their preferred habitat, it will reduce the ability of even protected areas to safeguard wildlife. The authors say that should be considered when assessing the potential climate-change effects on these species.
The study is co-authored by Rahel Sollmann, Rocha’s former advisor at UC Davis who is now at the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany.
The study was funded by CAPES, the National Geographic Society, Horodas Family Foundation for Conservation Research, The Explorers Club, Alongside Wildlife Foundation, and the Hellman Foundation. This study received logistical support from ICMBio.
Scientists examine jaguar tracks on a road in the Brazilian Amazon.
CREDIT
Fernanda Cavalcante/PCMC Brasil
A white-lipped peccary walks past a camera trap in the Brazilian Amazon. (Daniel Rocha/UC Davis)
CREDIT
Daniel Rocha, UC Davis
A marsh deer approaches the forest edge. It’s among the few mammals species not expected to be negatively affected by savannization in the Amazon
IMAGE: BOB RODE, AT LEFT, MANAGER OF THE AQUACULTURE RESEARCH LAB, AND TECHNICIAN IAN KOVACS TEND TO TILAPIA RAISED IN THE FACILITY. PAUL BROWN, PROFESSOR OF FORESTRY AND NATURAL RESOURCES AT PURDUE UNIVERSITY, OVERSEES THE LAB’S EXPERIMENTAL AQUAPONICS SYSTEMS.view more
CREDIT: PURDUE UNIVERSITY PHOTO/TOM CAMPBELL
WEST LAFAYETTE, Ind. — Purdue University has received a five-year, $10 million grant from the U.S. Department of Agriculture to increase the production of seafood, also known as “blue food,” which is healthier and more sustainably produced than land-based foods.
"Many studies indicate the importance of increasing seafood consumption in U.S. diets,” said Jen-Yi Huang, project director and associate professor of food science at Purdue University. Those studies show that seafood can boost intake of healthy omega-3 fatty acids, vitamins and minerals while also reducing more harmful substances such as cholesterol and saturated fat.
A 2021 blue food assessment published in the journal Nature found that a 15.5-million-ton increase in aquatic animal-source food by 2030 would decrease the price of such food by 26%. The resulting increase in blue food consumption would result in preventing an estimated 166 million cases of inadequate intake of micronutrients such as vitamin A, calcium and iron worldwide.
Seafood is readily available in local grocery stores, but most of it is imported from Asia and elsewhere. Such long-distance supply chains recently have proven vulnerable to volatile markets, fluctuating fuel costs, the COVID-19 pandemic and regional war, said Huang, who also holds a courtesy appointment in Environmental and Ecological Engineering.
About 90% of U.S. seafood comes from abroad, resulting in a $17 billion trade deficit. U.S. fisheries are not sustainable because of overfishing concerns, Huang noted. Aquaculture — growing aquatic organisms under controlled conditions — offers an alternative.
Aquaponics is a combination of aquaculture and hydroponics (growing plants in water) that offers the advantage of intensively producing seafood and plants using less land and water than conventional food production.
The Midwest especially could benefit from aquaponics. The region suffers high obesity rates, operates the fewest aquaculture farms and consumes the least amount of seafood.
“It can increase production yields, but aquaponics production hasn’t been widely adopted, especially in the Midwest,” Huang said. Energy use in the required greenhouse environment is one key reason.
Aquaponics operations require the daily discharge of up to 20% of wastewater into the environment. For large farms, that becomes a maintenance cost because they need permits to treat their wastewater before discharge.
Purdue researchers will build a pilot-scale integrated aquaponics system on campus to produce tilapia and lettuce. This zero-waste food production system will convert nutrient-rich waste into energy for system operation and high-value bioproducts.
CREDIT
Illustration by Tom Kronewitter
“The smaller farms don’t need permits,” Huang said. “They can discharge whatever they generate, which can cause environmental issues.”
With the USDA funding, Purdue researchers will build a pilot-scale integrated aquaponics system on campus, where some lab-scale components already exist, to produce tilapia and lettuce.
Also on the team is Nicole Wright, aquaculture extension educator at The Ohio State University.
“Algae cultivation and anaerobic digestion are two of the most important components in Purdue’s integrated aquaponic system,” Ni said. “We use the algae to treat the wastewater and also anaerobic digestion to treat the algal biomass and other waste streams like fish processing wastes.”
The Purdue system will direct the aquaponics wastewater discharge into algal bioreactors, where algae can feed on its nutrients. The next step is anaerobic digestion, which generates biogas fuel as one of its products.
"That energy can be sent back to the aquaponics system to offset the energy requirement of the indoor facility operation, at least partially,” Huang said. The system is designed to generate zero waste and to operate independently of the power grid.
The system also includes a biorefinery subsystem to convert algae and fish byproducts into high-value nutraceuticals such as bioactive peptide and phenolic compounds. The biorefinery can turn the algae into fish feed for the aquaponics operation as well.
“By integration with the biorefinery, we can have additional revenues for aquaponics farmers so that they can improve their economic viability,” Huang said. “We will develop multidimensional sustainability metrics for system assessment and management to make sure that this kind of integration is technically feasible, economically viable and environmentally friendly.”
The project will further include stakeholder education and outreach components. The research team will survey farmers and suppliers about the barriers and opportunities for blue foods and aquaponics. The team also will develop workshops to help interested farmers build aquaponics systems or improve their existing operations.
In addition, the grant will foster a workforce that can support blue food production by funding the creation of educational materials for high school, undergraduate and graduate students.
“We also want to educate consumers on the benefit of blue foods so that they can diversify their dietary pattern to include more blue foods and ultimately improve health,” Huang said.
