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Comment by Dr. Krishna Kumari Challa on January 13, 2023 at 11:30am

Study clarifies mystery of crocodilian hemoglobin

We know a crocodile's ability to stay under water for a long time.  When the unseen apex predator lashes from the water to seize its prey the impala, its infamous teeth latch onto a hindquarter, jaws clenching with 5,000 pounds of force. Yet it's the water itself that does the killing, with the deep-breathed reptile dragging its prey to the deep end to drown.

The success of the croc's ambush lies in the nanoscopic scuba tanks—hemoglobins—that course through its bloodstream, unloading oxygen from lungs to tissues at a slow but steady clip that allows it to go hours without air. The hyper-efficiency of that specialized hemoglobin has led some biologists to wonder why, of all the jawed vertebrates in all the world, crocodilians were the lone group to hit on such an optimal solution to making the most of a breath.

By statistically reconstructing and experimentally resurrecting the hemoglobin of an archosaur, the 240-million-year-old ancestor of all crocodilians and birds, researchers have gleaned new insights into that why. Rather than requiring just a few key mutations, as earlier research suggested, the unique properties of crocodilian hemoglobin stemmed from 21 interconnected mutations that litter the intricate component of red blood cells.

That complexity, and the multiple knock-on effects that any one mutation can induce in hemoglobin, may have forged an evolutionary path so labyrinthine that nature failed to retrace it even over tens of millions of years, the researchers say.

All hemoglobin binds with oxygen in the lungs before swimming the bloodstream and eventually releasing that oxygen to the tissues that depend on it. In most vertebrates, hemoglobin's affinity for capturing and holding oxygen is dictated largely by molecules known as organic phosphates, which, by attaching themselves to the hemoglobin, can coax it into releasing its precious cargo.

But in crocodilians—crocodiles, alligators and their kin—the role of organic phosphates was supplanted by a molecule, bicarbonate, that is produced from the breakdown of carbon dioxide. Because hardworking tissues produce lots of carbon dioxide, they also indirectly generate lots of bicarbonate, which in turn encourages hemoglobin to dispense its oxygen to the tissues most in need of it.

It's a super-efficient system that provides a kind of slow-release mechanism that allows crocodilians to efficiently exploit their onboard oxygen stores. It's part of the reason they're able to stay underwater for so long.

Chandrasekhar Natarajan et al, Evolution and molecular basis of a novel allosteric property of crocodilian hemoglobin, Current Biology (2022). DOI: 10.1016/j.cub.2022.11.049

Comment by Dr. Krishna Kumari Challa on January 11, 2023 at 7:05am

Introduction to Marine Energy

Want to learn about different types of marine energy resources and technologies, their associated challenges and considerations, and how researchers are addressing these challenges? Watch this video ....

Comment by Dr. Krishna Kumari Challa on January 11, 2023 at 7:01am

Are we breathing airborne microplastics? Study finds higher concentrations indoors

People are likely exposed to thousands of airborne microplastics a year indoors, a new study has found.

Published in Environmental Science & Technology, the study investigated the abundance, distribution, form, and possible sources of microplastics (MPs) in indoor and outdoor sites in Sri Lanka, finding concentrations between 1 and 28 times higher indoors.

With people spending approximately 90% of their time indoors and based on the indoor and outdoor MPs levels identified in this study, the researchers calculated the average human exposure as 2,675 airborne microplastic particles per person every year.

Researchers collected air samples in different urban, rural, coastal, inland, industrial, and natural habitats with varying population densities.

The indoor MPs levels, made up of fibers and the occasional fragments mostly from textiles and clothing, were significantly higher than outdoor levels by a factor of 1–28 times, regardless of the type of outdoor environment. Transparent, blue, and black fibers in the size range of 0.10 to 0.50 millimeters were the dominant AMPs across all sites.

These initial results  show that the amount of indoor airborne microplastics is more related to indoor sources and the occupants' lifestyle than the outdoor environment.

In the outdoor samples, the amount of AMPs was always greater in high-density sites compared to the low-density areas, suggesting the abundance and distribution of AMPs was related to population density, level of industrialization, and human activity."

The dominant type of microplastics in both indoor and outdoor sites was PET fibers (polyethylene terephthalate), primarily originating from clothing and textiles.

This study is an important first step that shows the abundance of AMPs in a lower-middle income country in South Asia.

Kushani Perera et al, Airborne Microplastics in Indoor and Outdoor Environments of a Developing Country in South Asia: Abundance, Distribution, Morphology, and Possible Sources, Environmental Science & Technology (2022). DOI: 10.1021/acs.est.2c05885

Comment by Dr. Krishna Kumari Challa on January 11, 2023 at 6:56am

Peering inside a metal, one sees atoms arranged in neat repeating grids, called a crystal lattice. In a crystal, the atomic orbitals of the outermost electrons morph into one another. This allows the electrons to travel far from their original nucleus and carry current through the metal. In this solid setting, a version of orbital balloons still exists, but it's more common to visualize them not in space—where there are many huge and unwieldy orbitals—but as a function of the speed and direction of the traveling electrons. The fastest moving electrons in the crystal form their own balloon, a collective analog of atomic orbitals known as a Fermi surface.

The shape of the Fermi surface reflects the structure of the underlying crystal, which usually bears no resemblance to the orbital structure of single atoms. But for materials like YPtBi with very few mobile electrons, the Fermi surface is not very big. Because of this, it retains some of the properties of electrons that hardly move at all, which sit at the center of the Fermi surface.

The fact that nature figures out counterintuitive atomic arrangements that allow the Fermi surface to retain signatures of the atomic orbitals is rather cool and intricate.

To uncover this cool, counterintuitive Fermi surface, the researchers stuck a YPtBi crystal inside a magnetic field and measured the current flowing through the crystal as they tuned the field. By rotating the direction of the magnetic field, they were able to map out the speed of the fastest electrons in every direction. They found that akin to a higher angular momentum atomic orbital, the Fermi surface has a complex shape to it, with peaks and troughs along certain directions. The high symmetry of the crystal itself would normally lead to a more uniform, ball-like Fermi surface, so it was a surprise to find a more complicated structure. This pointed to the possibility that the collective electrons were exhibiting some of the higher angular momentum nature of atomic orbitals.

Indeed, theoretical calculations by the  team showed that the experimental results matched up with a high angular momentum model, leading the team to claim the first experimental observation of a high-angular momentum metal. The team cautions that even this experimental evidence could still be incomplete. What they measured depends not only on the Fermi surface but also on other properties of the electrons, such as their effective mass and the distribution of their velocities. In their work, the team systematically studied the angular dependence of these other quantities and demonstrated that it would be extremely unlikely for them to cause the observed peaks and troughs.

In addition to being fundamentally novel, this higher angular momentum metal has potential applications for quantum computing.

Hyunsoo Kim et al, Quantum oscillations of the j=3/2 Fermi surface in the topological semimetal YPtBi, Physical Review Research (2022). DOI: 10.1103/PhysRevResearch.4.033169

**

Part2

Comment by Dr. Krishna Kumari Challa on January 11, 2023 at 6:54am

Electrons take new shape inside unconventional metal

One of the biggest achievements of quantum physics was recasting our vision of the atom. Out was the early 1900s model of a solar system in miniature, in which electrons looped around a solid nucleus. Instead, quantum physics showed that electrons live a far more interesting life, meandering around the nucleus in clouds that look like tiny balloons. These balloons are known as atomic orbitals, and they come in all sorts of different shapes—perfectly round, two-lobed, clover-leaf-shaped. The number of lobes in the balloon signifies how much the electron spins about the nucleus.

That's all well and good for individual atoms, but when atoms come together to form something solid—like a chunk of metal, say—the outermost electrons in the atoms can link arms and lose sight of the nucleus from where they came, forming many oversized balloons that span the whole chunk of metal. They stop spinning about their nuclei and flow through the metal to carry electrical currents, shedding the diversity of multi-lobed balloons.

Now researchers have produced the first experimental evidence that one metal—and likely others in its class—have electrons that manage to preserve a more interesting, multi-lobed structure as they move around in a solid. The team experimentally studied the shape of these balloons and found not a uniform surface, but a complex structure. This unusual metal is not only fundamentally interesting, but it could also prove useful for building quantum computers that are resistant to noise.

Part 1

Comment by Dr. Krishna Kumari Challa on January 11, 2023 at 6:42am

Researchers uncover new cell types involved in osteoarthritis

A  Medicine study has identified a new potential target for treating osteoarthritis—a debilitating joint disease that affects  millions and is a leading cause of disability worldwide.

A team of researchers  has uncovered previously unknown cell types in the joint that emerge after an injury and drive the onset of osteoarthritis.

Clinically, osteoarthritis presents as a very complex disease, with patients suffering from joint stiffness, reduced mobility and function, and most notably, persistent pain.

Osteoarthritis patients commonly live with this condition for multiple decades, and no treatments have been developed that can stop or reverse the disease. The condition can occur with age or be sparked by a joint injury and is typically managed with pain relief and end-stage joint replacement.

The study, titled "Synovial fibroblasts assume distinct functional identities and secrete R-spondin 2 in osteoarthritis" and published in the Annals of the Rheumatic Diseases, examined the cellular and molecular events during the onset of post-traumatic osteoarthritis in joints.

Researchers  identified cell types that emerge in the joint after trauma, such as an ACL injury, and they can now associate these cells with the disease process. This allows us to view them as a treatment target for this devastating disease.

By employing a cutting-edge gene sequencing technology called single-cell RNA-sequencing,the researchers were able to uncover these previously uncharacterized cells that emerge in the joint after injury.

The study also described the biological processes that may activate these cells, which offers compelling new targets for an effective treatment.

Interestingly, these cells are not found in healthy joints, and the researchers have to understand exactly what causes them to appear and how they may cause osteoarthritis.

Alexander J Knights et al, Synovial fibroblasts assume distinct functional identities and secrete R-spondin 2 in osteoarthritis, Annals of the Rheumatic Diseases (2022). DOI: 10.1136/ard-2022-222773

Comment by Deepak Menon on January 10, 2023 at 5:18pm

An interesting thought indeed "Researchers blamed a global trend of academics being "forced to slice up their papers" to increase their number of publications, saying it had led to "a dulling of research."
So, Dr Krishna - where does this lead scientists to? Does it indicate a progressive movement towards applied Physics?

Comment by Dr. Krishna Kumari Challa on January 10, 2023 at 8:44am

Method reviews could stop useless science

“I’ve lost count of the number of times that a board member has remarked that the way a study has been designed means it won’t yield any informative data,” says experimental psychologist and ethical-review-board chair Daniël Lakens. To counter this trend, his university has introduced a methodological review board that highlights flaws before data col... — such as sample sizes that are too small to test a hypothesis.

Comment by Dr. Krishna Kumari Challa on January 10, 2023 at 8:32am

Human-approved medication brings back 'lost' memories in mice

Students sometimes pull an all-nighter to prepare for an exam. However, research has shown that sleep deprivation is bad for your memory. Now,  neuroscientists have discovered that what you learn while being sleep deprived is not necessarily lost, it is just difficult to recall.

These neuro-scientists have found a way to make this "hidden knowledge" accessible again days after studying while sleep-deprived using optogenetic approaches, and the human-approved asthma drug roflumilast. These findings were published in the journal Current Biology.

 Using genetic techniques, the scientists caused a light-sensitive protein (channelrhodopsin) to be produced selectively in neurons that are activated during a learning experience. This made it possible to recall a specific experience by shining light on these cells.

In the experiment,  the genetically engineered mice were given a spatial learning task in which they had to learn the location of individual objects, a process that heavily relies on neurons in the hippocampus. The mice then had to perform this same task days later, but this time with one object moved to a novel location. The mice that were deprived of sleep for a few hours before the first session failed to detect this spatial change, which suggests that they cannot recall the original object locations.

However, when the researchers reintroduced them to the task after reactivating the hippocampal neurons that initially stored this information with light, they did successfully remember the original locations. This shows that the information was stored in the hippocampus during sleep deprivation, but couldn't be retrieved without the stimulation.

The molecular pathway set off during the reactivation is also targeted by the drug roflumilast, which is used by patients with asthma or COPD. When scientists gave mice that were trained while being sleep deprived roflumilast just before the second test, they remembered, exactly as happened with the direct stimulation of the neurons. As roflumilast is already clinically approved for use in humans, and is known to enter the brain, these findings open up avenues to test whether it can be applied to restore access to 'lost' memories in humans.

The discovery that more information is present in the brain than we previously anticipated, and that these "hidden" memories can be made accessible again—at least in mice—opens up all kinds of exciting possibilities.

 Youri G. Bolsius et al, Recovering object-location memories after sleep deprivation-induced amnesia, Current Biology (2022). DOI: 10.1016/j.cub.2022.12.006

Comment by Dr. Krishna Kumari Challa on January 9, 2023 at 11:53am

Rate of scientific breakthroughs slowing over time: Study

The rate of ground-breaking scientific discoveries and technological innovation is slowing down despite an ever-growing amount of knowledge, according to an analysis released recently of millions of research papers and patents.

While previous research has shown downturns in individual disciplines, the study is the first that 'emphatically, convincingly documents this decline of disruptiveness across all major fields of science and technology'.

The researchers gave a "disruptiveness score" to 45 million scientific papers dating from 1945 to 2010, and to 3.9 million US-based patents from 1976 to 2010.

From the start of those time ranges, research papers and patents have been increasingly likely to consolidate or build upon previous knowledge, according to results published in the journal Nature.

The ranking was based on how the papers were cited in other studies five years after publication, assuming that the more disruptive the research was, the less its predecessors would be cited.

The biggest decrease in disruptive research came in physical sciences such as physics and chemistry.

"The nature of research is shifting" as incremental innovations become more common.

One theory for the decline is that all the "low-hanging fruit" of science has already been plucked.

If that were the case, disruptiveness in various scientific fields would have fallen at different speeds. If that were the case, disruptiveness in various scientific fields would have fallen at different speeds.

But instead the declines are pretty consistent in their speeds and timing across all major fields indicating that the low-hanging fruit theory is not likely to be the culprit.

Instead, the researchers pointed to what has been dubbed "the burden of research," which suggests there is now so much that scientists must learn to master a particular field they have little time left to push boundaries.

This causes scientists and inventors to focus on a narrow slice of the existing knowledge, leading them to just come up with something more consolidating rather than disruptive. 

Another reason could be that "there's increasing pressure in academia to publish, publish, publish, because that's the metric that academics are assessed on.

The researchers called on universities and funding agencies to focus more on quality, rather than quantity, and consider full subsidies for year-long sabbaticals to allow academics to read and think more deeply.

 This work showed that "ultra-specialization" and the pressure to publish had increased over the years.

Researchers blamed a global trend of academics being "forced to slice up their papers" to increase their number of publications, saying it had led to "a dulling of research."

Michael Park et al, Papers and patents are becoming less disruptive over time, Nature (2023). DOI: 10.1038/s41586-022-05543-x

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