Tuesday, April 30, 2019
Scientists have long known that Earth and Mercury have metallic cores. Like Earth, Mercury’s outer core is composed of liquid metal, but there have only been hints that Mercury’s innermost core is solid. Now, in a new study, scientists report evidence that Mercury’s inner core is indeed solid and that it is very nearly the same size as Earth’s solid inner core.
Some scientists compare Mercury to a cannonball because its metal core fills nearly 85 percent of the volume of the planet. This large core — huge compared to the other rocky planets in our solar system — has long been one of the most intriguing mysteries about Mercury. Scientists had also wondered whether Mercury might have a solid inner core.
The findings of Mercury’s solid inner core, published in AGU’s journal Geophysical Research Letters, help scientists better understand Mercury but also offer clues about how the solar system formed and how rocky planets change over time.
“Mercury’s interior is still active, due to the molten core that powers the planet’s weak magnetic field, relative to Earth’s,” said Antonio Genova, an assistant professor at Sapienza University of Rome who led the research while at NASA Goddard Space Flight Center in Greenbelt, Maryland. “Mercury’s interior has cooled more rapidly than our planet’s. Mercury may help us predict how Earth’s magnetic field will change as the core cools.”
To figure out what Mercury’s core is made of, Genova and his colleagues had to get, figuratively, closer. The team used several observations from NASA’s MESSENGER mission to probe Mercury’s interior. The researchers looked, most importantly, at the planet’s spin and gravity.
The MESSENGER spacecraft entered orbit around Mercury in March 2011 and spent four years observing this nearest planet to our Sun until it was deliberately brought down to the planet’s surface in April 2015.
Scientists used radio observations from MESSENGER to determine Mercury’s gravitational anomalies (areas of local increases or decreases in mass) and the location of its rotational pole, which allowed them to understand the orientation of the planet.
Each planet spins on an axis, also known as the pole. Mercury spins much more slowly than Earth, with its day lasting about 58 Earth days. Scientists often use tiny variations in the way an object spins to reveal clues about its internal structure. In 2007, radar observations made from Earth revealed small shifts in Mercury’s spin, called librations, that proved some of the planet’s core must be liquid-molten metal. But observations of the spin rate alone were not sufficient to give a clear measurement of what the inner core was like. Could there be a solid core lurking underneath, scientists wondered?
Gravity can help answer that question. “Gravity is a powerful tool to look at the deep interior of a planet because it depends on the planet’s density structure,” said Sander Goossens, a researcher at NASA Goddard and co-author of the new study.
As MESSENGER orbited Mercury over the course of its mission and got closer and closer to the surface, scientists recorded how the spacecraft accelerated under the influence of the planet’s gravity. The density structure of a planet can create subtle changes in a spacecraft’s orbit. In the later parts of the mission, MESSENGER flew about 120 miles above the surface, and less than 65 miles during its last year. The final low-altitude orbits provided the best data yet and allowed for Genova and his team to make the most accurate measurements about the internal structure of Mercury yet taken.
Genova and his team put data from MESSENGER into a sophisticated computer program that allowed them to adjust parameters and figure out what the interior composition of Mercury must be like to match the way it spins and the way the spacecraft accelerated around it. The results showed that for the best match, Mercury must have a large, solid inner core. They estimated that the solid, iron core is about 1,260 miles (2,000 kilometers) wide and makes up about half of Mercury’s entire core (about 2,440 miles, or nearly 4,000 kilometers, wide). In contrast, Earth’s solid core is about 1,500 miles (2,400 kilometers) across, taking up a little more than a third of this planet’s entire core.
“We had to pull together information from many fields: geodesy, geochemistry, orbital mechanics and gravity to find out what Mercury’s internal structure must be,” said Erwan Mazarico, a planetary scientist at NASA Goddard and co-author of the new study.
The fact that scientists needed to get close to Mercury to find out more about its interior highlights the power of sending spacecraft to other worlds, according to the researchers. Such accurate measurements of Mercury’s spin and gravity were simply not possible to make from Earth. New discoveries about Mercury are practically guaranteed to be waiting in MESSENGER’s archives, with each discovery about our local planetary neighborhood giving us a better understanding of what lies beyond.
“Every new bit of information about our solar system helps us understand the larger universe,” Genova said.
A diet rich in animal protein and meat in particular is not good for the health, a new study from the University of Eastern Finland finds, providing further backing for earlier research evidence. Men who favored animal protein over plant-based protein in their diet had a greater risk of death in a 20-year follow-up than men whose diet was more balanced in terms of their sources of protein. The findings were published in the American Journal of Clinical Nutrition.
Men whose primary sources of protein were animal-based had a 23% higher risk of death during the follow-up than men who had the most balanced ratio of animal and plant-based protein in their diet. A high intake of meat in particular seemed to associate with adverse effects: men eating a diet rich in meat, i.e. more than 200 grams per day, had a 23% greater risk of death during the follow-up than men whose intake of meat was less than 100 grams per day. The men participating in the study mainly ate red meat. Most nutrition recommendations nowadays limit the intake of red and processed meats. In Finland, for example, the recommended maximum intake is 500 grams per week.
The study also found that a high overall intake of dietary protein was associated with a greater risk of death in men who had been diagnosed with type 2 diabetes, cardiovascular disease or cancer at the onset of the study. A similar association was not found in men without these diseases. The findings highlight the need to investigate the health effects of protein intake especially in people who have a pre-existing chronic medical condition. The mean age of the men participating in the study was 53 years at the onset, and diets clearly lacking in protein were not typical among the study population.
“However, these findings should not be generalised to older people who are at a greater risk of malnutrition and whose intake of protein often remains below the recommended amount,” PhD Student Heli Virtanen from the University of Eastern Finland points out.
Earlier studies have suggested that a high intake of animal protein, and especially the consumption of processed meats such as sausages and cold cuts, is associated with an increased risk of death. However, the big picture relating to the health effects of protein and different protein sources remains unclear.
The study is based on the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) that analysed the dietary habits of approximately 2,600 Finnish men aged between 42 and 60 at the onset of the study in 1984-1989. The researchers studied the mortality of this study population in an average follow-up of 20 years by analysing registers provided by Statistics Finland. The analyses focused on the associations of dietary protein and protein sources with mortality during the follow-up, and other lifestyle factors and dietary habits were extensively controlled for, including the fact that those eating plenty of plant-based protein followed a healthier diet.
Monday, April 29, 2019
Researchers at the University of Minnesota have developed a unique 3D-printed transparent skull implant for mice that provides an opportunity to watch activity of the entire brain surface in real time. The device allows fundamental brain research that could provide new insight for human brain conditions such as concussions, Alzheimer’s and Parkinson’s disease.
The research is published in Nature Communications. Researchers also plan to commercialize the device, which they call See-Shell.
“What we are trying to do is to see if we can visualize and interact with large parts of the mouse brain surface, called the cortex, over long periods of time. This will give us new information about how the human brain works,” said Suhasa Kodandaramaiah, Ph.D., a co-author of the study and University of Minnesota Benjamin Mayhugh Assistant Professor of Mechanical Engineering in the College of Science and Engineering. “This technology allows us to see most of the cortex in action with unprecedented control and precision while stimulating certain parts of the brain.”
In the past, most scientists have looked at small regions of the brain and tried to understand it in detail. However, researchers are now finding that what happens in one part of the brain likely affects other parts of the brain at the same time.
One of their first studies using the See-Shell device examines how mild concussions in one part of the brain affect other parts of the brain as it reorganizes structurally and functionally. Kodandaramaiah said that mouse brains are very similar in many respects to human brains, and this device opens the door for similar research on mice looking at degenerative brain diseases that affect humans such as Alzheimer’s or Parkinson’s disease.
The technology allows the researchers to see global changes for the first time at an unprecedented time resolution. In a video produced using the device, changes in brightness of the mouse’s brain correspond to waxing and waning of neural activity. Subtle flashes are periods when the whole brain suddenly becomes active. The researchers are still trying to understand the reason for such global coordinated activity and what it means for behavior.
See film: https://www.youtube.com/watch?v=pETFswXWx0E
To make the See-Shell, researchers digitally scanned the surface of the mouse skull and then used the digital scans to create an artificial transparent skull that has the same contours as the original skull. During a precise surgery, the top of the mouse skull is replaced with the 3D-printed transparent skull device. The device allows researchers to record brain activity simultaneously while imaging the entire brain in real time.
Another advantage to using this device is that the mouse’s body did not reject the implant, which means that the researchers were able to study the same mouse brain over several months. Studies in mice over several months allow researchers to study brain aging in a way that would take decades to study in humans.
“This new device allows us to look at the brain activity at the smallest level zooming in on specific neurons while getting a big picture view of a large part of the brain surface over time,” Kodandaramaiah said. “Developing the device and showing that it works is just the beginning of what we will be able to do to advance brain research.”
Saturday, April 27, 2019
Using CRISPR gene editing, a team from Children’s Hospital of Philadelphia (CHOP)and Penn Medicine have thwarted a lethal lung disease in an animal model in which a harmful mutation causes death within hours after birth. This proof-of-concept study, published today in Science Translational Medicine, showed that in utero editing could be a promising new approach for treating lung diseases before birth.
“The developing fetus has many innate properties that make it an attractive recipient for therapeutic gene editing,” said study co-leader William H. Peranteau, MD, an investigator at CHOP’s Center for Fetal Research, and a pediatric and fetal surgeon in CHOP’s Center for Fetal Diagnosis and Treatment. “Furthermore, the ability to cure or mitigate a disease via gene editing in mid- to late gestation before birth and the onset of irreversible pathology is very exciting. This is particularly true for diseases that affect the lungs, whose function becomes dramatically more important at the time of birth.”
The lung conditions the team is hoping to solve–congenital diseases such as surfactant protein deficiency, cystic fibrosis, and alpha-1 antitrypsin–are characterized by respiratory failure at birth or chronic lung disease with few options for therapies. About 22 percent of all pediatric hospital admissions are because of respiratory disorders, and congenital causes of respiratory diseases are often lethal, despite advances in care and a deeper understanding of their molecular causes. Because the lung is a barrier organ in direct contact with the outside environment, targeted delivery to correct defective genes is an attractive therapy.
“We wanted to know if this could work at all,” said study co-leader Edward E. Morrisey, PhD, a professor of Cardiovascular Medicine in the Perelman School of Medicine at the University of Pennsylvania. “The trick was how to direct the gene-editing machinery to target cells that line the airways of the lungs.”
The researchers showed that precisely timed in utero delivery of CRISPR gene-editing reagents to the amniotic fluid during fetal development resulted in targeted changes in the lungs of mice. They introduced the gene editors into developing mice four days before birth, which is analogous to the third trimester in humans.
The cells that showed the highest percentage of editing were alveolar epithelial cells and airway secretory cells lining lung airways. In 2018, a team led by Morrisey identified the alveolar epithelial progenitor (AEP) lineage, which is embedded in a larger population of cells called alveolar type 2 cells. These cells generate pulmonary surfactant, which reduces surface tension in the lungs and keeps them from collapsing with every breath. AEPs are a stable cell type in the lung and turn over very slowly, but replicate rapidly after injury to regenerate the lining of the alveoli and restore gas exchange.
In a second experiment, the researchers used prenatal gene-editing to reduce the severity of an interstitial lung disease, surfactant protein C (SFTPC) deficiency, in a mouse model that has a common disease-causing mutation found in the human SFTPC gene. One hundred percent of untreated mice with this mutation die from respiratory failure within hours of birth. In contrast, prenatal gene editing to inactivate the mutant Sftpc gene resulted in improved lung morphology and survival of over 22 percent of the animals.
Future studies will be directed towards increasing the efficiency of the gene editing in the epithelial lining of lungs as well as evaluating different mechanisms to deliver gene editing technology to lungs. “Different gene editing techniques are also being explored that may one day be able to correct the exact mutations observed in genetic lung diseases in infants,” Morrisey said.
Morrisey collaborated on a recent study led by Peranteau and Kiran Musunuru, MD, PhD, an associate professor of Cardiovascular Medicine at Penn, demonstrating the feasibility of in utero gene editing to rescue a lethal metabolic liver disease in a mouse model – the first time in utero CRISPR-mediated gene editing prevented a lethal metabolic disorder in animals. Similar to that study, Peranteau says “the current research is a proof-of-concept study highlighting the exciting future prospects for prenatal treatments including gene editing and replacement gene therapy for the treatment of congenital diseases.”