“Our study shows that Aegyptopithecus preserves an ancient hip morphology not present in living anthropoid primates,” said Sergio Almécija, a paleoanthropologist and evolutionary biologist in the Division of Anthropology at the American Museum of Natural History who is first author on the study, which was published in Nature Communications this week. “As far as the hip is concerned, it seems that apes, humans, and Old World monkeys have all parted ways long ago — which would explain why they move around so differently today.”

The fossil analyzed in the study was discovered in 2009 and is the most complete femur of Aegyptopithecus, a 15-lb (7-kg) likely tree-dwelling species that lived in Egypt about 30 million years ago, close to the time when hominoids (the group that includes apes and humans) split from the larger group that includes Old World monkeys. A well-preserved femur allowed researchers to glean details about the hip joint, a major anatomical region for inferring locomotion, using a combination of 3D morphometric analysis and evolutionary modeling.

For the analysis, the authors compared the fossil bone to other extinct and modern species, including humans, chimpanzees, and Victoriapithecus and Homunculus (extinct Old World and New World monkeys, respectively). The evolutionary modeling analysis used in the study included a method that was developed to identify convergent evolution in anole lizards in the Caribbean, which have independently developed comparable niche-specific adaptations across various islands.

The results indicate that the ancestral hip joint is, from an evolutionary perspective, as far from the hip joint of modern Old World monkeys as from those of the great apes — suggesting that each group evolved a distinct way of moving as they specialized for success in different environmental niches.

In addition, evolutionary modeling suggests that living great apes — including orangutans, chimpanzees, and gorillas — may have independently developed similar hip joint anatomy that allows wide-ranging, flexible movement through their arboreal habitats.

“What I find really exciting about the modeling approach is that we can develop better hypotheses about what drove the divergence of apes and monkeys, and the emerging picture is that navigating the environment is one of the key factors,” said Ashley Hammond, assistant curator in the Division of Anthropology and an author on the study.

Story Source:

Materials provided by American Museum of Natural History. Note: Content may be edited for style and length.

The research conducted in mice found that the time-of-day dependent metabolic cycle is altered by high caloric diet. Since glucocorticoids are widely used drugs for the treatment of inflammatory diseases, these findings published in Molecular Cell suggest that lean and obese patients might respond differently to steroid therapy. Finally, it reveals the biological function of daily rhythms of hormone secretion (high before awakening and feeding, low when sleeping and fasting) as well as daily cycles of sugar and fat storage or release by the liver.

Each cell in the human body is driven by an internal clock which follows the circadian rhythm of 24 hours. It is synchronized with the natural cycle of day and night mainly by sunlight, but also through social habits. In a healthy system, glucocorticoid stress hormones, are produced every morning by the adrenal gland. The secretion of glucocorticoidpeaks before awakening, prompting the body to use fatty acids and sugar as sources of energy, and enabling us to start our daily activities. When the circadian rhythm is disrupted (e.g. through shift work or jetlag) and/or when the glucocorticoid level alters (e.g. through Cushing syndrome or long-term clinical application), profound metabolic dysregulation can be caused — like obesity, type 2 diabetes, and fatty liver disease. The researcher’s goal therefore was to understand the relevance of these daily peaks of stress hormone secretion, the impact of these hormones on our “internal clock” and their role for daily cycles of metabolism.

Glucocorticoids’ metabolic actions in the liver

To study glucocorticoids’ metabolic actions in the liver, the researchers characterized the activity of their receptor, called the glucocorticoid receptor, using novel high throughput techniques. They analyzed mouse livers every 4 hours during day and night. The mice were either in normal condition or fed with high-fat diet. They then used cutting-edge technologies in genomics, proteomics, and bioinformatics to picture when and where the glucocorticoid receptor exerts its metabolic effects. The researchers dissected the impact of daily surges of glucocorticoid release in the 24-hour-cycle of liver metabolism. They could illustrate how glucocorticoids regulate metabolism differently during fasting (when the mice sleep) and during feeding (when they are active), by time-dependent binding to the genome. Furthermore, they showed how the majority of rhythmic gene activity is controlled by these hormones. When this control is lost (in so-called knockout mice), blood levels of sugar and fat are affected. This explains how the liver controls blood levels of sugar and fat differently during day and night.

In a next step, as the glucocorticoid receptor is a widely-used drug target in immune therapies, they investigated its genomics effects after the injection of the drug dexamethasone, a synthetic glucocorticoid that also activates this receptor. “With this experiment,” explains Dr. Fabiana Quagliarini, “we found that the drug response was different in obese mice compared to lean mice. It is the first time to show that diet can change hormonal and drug responses of metabolic tissues.”

New insights for Chronomedicine and metabolic disease therapy

Glucocorticoids are a group of natural and synthetic steroid hormones such as cortisol. They have potent anti-inflammatory and immunosuppressive properties which can control the activity of the immune system. This is why they are widely exploited in medicine. The major drawback is that glucocorticoids also cause severe side effects by virtue of their ability to modulate sugar and fat metabolism: Patients may develop obesity, hypertriglyceridemia, fatty liver, hypertension or type 2 diabetes.

“Understanding how glucocorticoids control 24-hour-cycles of gene activity in the liver and consequently blood levels of sugar and fat, provides new insights into ‘Chronomedicine’ and the development of metabolic disease. We could describe a new link between lifestyle, hormones and physiology at the molecular level, suggesting that obese people may respond differently to daily hormone secretion or to glucocorticoid drugs. These mechanisms are the basis for the design of future therapeutic approaches,” highlights Prof. Henriette Uhlenhaut.

“Carbon budgets and climate simulations have so far missed coastal erosion in their equations even though it might be a substantial source of carbon dioxide,” says George Tanski of Vrije Universiteit Amsterdam, lead author of the study. “Our research found that the erosion of permafrost coastlines can lead to the rapid release of significant quantities of CO₂, which can be expected to increase as coastal erosion accelerates, temperatures increase, sea ice diminishes, and stronger storms batter Arctic coasts.”

The study was carried out during Tanski’s time at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), and the GFZ German Research Centre for Geosciences. Co-Authors come from AWI, GFZ, and the Universities of Hamburg and Potsdam. The study is part of the Nunataryuk research project, coordinated by AWI. The project aims to analyse permafrost thaw, understand its impacts on indigenous communities and other populations, and develop mitigation and adaptation strategies.

Simulating erosion effects in the lab

For the new study, the researchers simulated the effects of erosion in a lab experiment. To find out how much carbon is released into the atmosphere along eroding Arctic permafrost coasts, they collected permafrost samples from Qikiqtaruk (also known as Herschel Island) off the northern coast of the Yukon in northwest Canada, and seawater from offshore. They mixed permafrost and seawater samples and then measured the greenhouse gases emitted over the course of four months, the average length of open-water season in the Arctic.

The researchers found that CO₂ was released as rapidly from thawing permafrost in seawater as it is from thawing permafrost on land. Previous research had documented that thawing permafrost on land causes significant releases of greenhouse gases. This new research indicates that eroding permafrost coasts and nearshore waters are also a potentially notable source of CO₂ emissions. It draws into question carbon budgets that have identified the coastal zone mainly as a point of passage for carbon from land to sea, neglecting possible carbon transport into the atmosphere.

Story Source:

Materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre. Note: Content may be edited for style and length.

The Big Bang started the universe as a hot, murky soup of extremely energetic particles that was rapidly expanding. As this material spread out, it cooled, and the particles coalesced into neutral hydrogen gas. The universe stayed dark, without any luminous sources, until gravity condensed matter into the first stars and galaxies.

All stars, including this first generation, act as chemical factories, synthesizing almost all of the elements that make up the world around us. When the original stars exploded as supernovae, they spewed out the elements that they created, seeding the surrounding gas. Subsequent generations of stars incorporated these elements and steadily increased the chemical abundances of their surroundings.

But the first stars formed in a still pristine, cold universe. Consequently these initial stars produced elements in different proportions than those synthesized by younger stars, which were formed in an environment that was already enriched by earlier generations.

“Looking back in time far enough, one may expect cosmic gas clouds to show the tell-tale signature of the peculiar element ratios made by the first stars,” said Rauch. “Peering even further back, we may ultimately witness the disappearance of most elements and the emergence of pristine gas.”

Astronomers have long used quasars to learn about the chemical composition of cosmic gas over time, showing how different generations of stars enrich their surroundings.

“We found this ancient gas cloud when following up on an inventory of very distant quasars using the Magellan telescopes at Carnegie’s Las Campanas Observatory in Chile,” explained Bañados, who is now a group leader at the Max-Planck Institute in Heidelberg.

Quasars are tremendously luminous objects comprised of enormous black holes accreting matter at the centers of massive galaxies. Because the gas cloud exists between the quasar and us on Earth, the quasar’s incredibly bright light must pass through it to get to us and astronomers can take advantage of this to understand the cloud’s chemistry. This discovery presented an unprecedented opportunity to characterize a gas cloud from the first billion years of cosmic history.

The team found that the cloud’s chemical makeup was quite modern, and not as primitive as expected if dominated by the first stars. Although it formed only 850 million years after the Big Bang, its chemical abundances were already as high as those typically seen in cosmic gas clouds that were formed several billion years later.

“Apparently, the first generation of stars had already expired by the time the cloud formed,” Rauch explained. “This shows that the universe was rapidly swamped by the chemical products of later generations of stars, even before most of the present-day galaxies were in place.”

The team is optimistic that even-more-ancient gas clouds will eventually be discovered and that they will reveal information about the first stars in the universe.

Story Source:

Materials provided by Carnegie Institution for Science. Note: Content may be edited for style and length.

In a new paper published in Physical Review Letters, the researchers suggest that such large mergers could happen just outside supermassive black holes at the center of active galactic nuclei. Gas, stars, dust and black holes become caught in a region surrounding supermassive black holes known as the accretion disk. The researchers suggest that as black holes circle around in the accretion disk, they eventually collide and merge to form a bigger black hole, which continues to devour smaller black holes, becoming increasingly large in what O’Shaughnessy calls “Pac-Man-like” behavior.

“This is a very tantalizing prospect for those of us who work in this field,” said O’Shaughnessy, a member of RIT’s Center for Computational Relativity and Gravitation (CCRG). “It offers a natural way to explain high mass, high spin binary black hole mergers and to produce binaries in parts of parameter space that the other models cannot populate. There is no way to get certain types of black holes out of these other formation channels.”

As the LIGO and Virgo collaboration continue to hunt for gravitational waves, O’Shaughnessy and his fellow researchers hope to find signatures of large, spinning black holes that could help confirm their models. If their assumptions are correct, it could help us better understand how the cosmic web of galaxies assembles.

“This could be a unique way of probing the physics around these supermassive black holes in a way that could not be probed in any other way,” said O’Shaughnessy. “It offers unique insight into how the centers of galaxies grow, which is of course essential to understanding how galaxies as a whole grow, which explains most of the structure in the universe.”

Story Source:

Materials provided by Rochester Institute of Technology. Original written by Luke Auburn. Note: Content may be edited for style and length.

Testing devices have been improved using different geometries in the testing chamber, and more recently, better results have been achieved using information from rheological testing coupled with results from other tests, such as inner visualization techniques and ultrasonic imaging. But traditional methods have been unable to produce information about time-dependent properties.

In a study published this week in Physics of Fluids, from AIP Publishing, Taiki Yoshida, Yuji Tasaka and Peter Fischer introduce an updated method that can measure linear viscoelasticity and phase lag simultaneously in an opaque liquid. The ultrasonic spinning rheometry method they developed substitutes velocity profiles of food into the equation of motion to capture information about complex rheological properties.

The researchers used a popular Japanese dessert called Fruiche, which includes fruit pulp and whole milk that transforms into a gelled form with an egg carton-shaped structure. The complexity of this liquid includes properties that are hard to measure with traditional rheometry methods because of the effect of shear history, shear banding, shear localization, wall slip and elastic instability.

“Evaluation of food rheology with time dependence is challenging target,” Yoshida said. “Based on the equation of motion, the ultrasonic spinning rheometry method can evaluate instantaneous rheological properties from the measured velocity profiles, so it can present true rheological properties and their time dependence from the perspective of physics of fluids.”

The updated method has applications in chemical engineering for understanding polymerization and dispersion densities, as well as in complex fluids such as clay, with applications in civil engineering and cosmetics. The researchers plan to further advance the method to include more points at which information can be gathered about the invisible properties of complex liquids. They also plan to further develop the industrial aspects of the technique, including in-line rheometry for test samples flowing in a pipe.

Story Source:

Materials provided by American Institute of Physics. Note: Content may be edited for style and length.