Comment

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 8:31am

A free-living eukaryote is the first known to have lost its mitochondria

An international team of geneticists and molecular biologists has discovered the first-known, free-living eukaryote to have lost its mitochondria. In their study, published in Nature Communications, the group found the eukaryote while investigating the patterns and processes of genome and mitochondrion-related organelles' evolution in metamonads in water samples collected from saltwater lakes and shallow marine environments.

Mitochondria are organelles in almost every living eukaryotic cell on Earth. They are responsible for generating the energy that allows creatures to grow and to move around. Mitochondria have a double membrane and use aerobic respiration to generate adenosine triphosphate (ATP)—the fuel that provides the energy for the cell. Eukaryotes belong to one of four types: plants, animals, fungi and protists.

Prior research has shown that there are eukaryotes that have devolved mitochondria to the point that they have none—generally because they get their energy elsewhere. Such creatures are able to gather energy by absorbing nutrients directly from another creature that does have functioning mitochondria—several have been found in the human gut, for example.

For this new research, the team studied eukaryote evolution in metamonads, a type of microscopic eukaryote. They collected specimens from various locations and studied them in their lab. They found five that caught their eye: three found in salty soda lake sediment beds and two in shallow ocean sediments.

One stood out clearly from the other four due to its complete lack of mitochondria. They named it Skoliomonas litria and noted that it was the first-ever finding of a free-living eukaryote to have lost its mitochondria. They also note that more work is required to determine how the creature makes its ATP without using oxygen.

Shelby K. Williams et al, Extreme mitochondrial reduction in a novel group of free-living metamonads, Nature Communications (2024). DOI: 10.1038/s41467-024-50991-w

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 8:27am

If you have protocell populations that are unstable, they will exchange their genetic material with each other and become clones. There is no possibility of Darwinian evolution. But if they stabilize against exchange so that they store their genetic information well enough, at least for several days, so that the mutations can happen in their genetic sequences, then a population can evolve.
In their experiments with the actual rainwater and with lab water modified to mimic the acidity of rainwater, the researchers found the same results. The meshy walls formed, creating the conditions that could have led to life.
The new paper proves that this approach of building a meshy wall around protocells is possible and can work together to compartmentalize the molecules of life, putting researchers closer than ever to finding the right set of chemical and environmental conditions that allow protocells to evolve.

Aman Agrawal et al, Did the exposure of coacervate droplets to rain make them the first stable protocells?, Science Advances (2024). DOI: 10.1126/sciadv.adn9657. www.science.org/doi/10.1126/sciadv.adn9657

Part 2

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 8:24am

New research suggests rainwater helped form the first protocell walls

In the paper, published in Science Advances researchers show how rainwater could have helped create a meshy wall around protocells 3.8 billion years ago, a critical step in the transition from tiny beads of RNA to every bacterium, plant, animal, and human that ever lived.

The research looks at "coacervate droplets"—naturally occurring compartments of complex molecules like proteins, lipids, and RNA. The droplets, which behave like drops of cooking oil in water, have long been eyed as a candidate for the first protocells. But there was a problem. It wasn't that these droplets couldn't exchange molecules between each other, a key step in evolution, the problem was that they did it too well, and too fast.

Any droplet containing a new, potentially useful pre-life mutation of RNA would exchange this RNA with the other RNA droplets within minutes, meaning they would quickly all be the same. There would be no differentiation and no competition—meaning no evolution.

And that means no life. If molecules continually exchange between droplets or between cells, then all the cells after a short while will look alike, and there will be no evolution because you are ending up with identical clones.

DNA is the molecule which encodes information, but it cannot do any function. Proteins are the molecules which perform functions, but they don't encode any heritable information.

RNA is a molecule which, like DNA, can encode information, but it also folds like proteins so that it can perform functions such as catalysis as well.

RNA was a likely candidate for the first biological material. Coacervate droplets were likely candidates for the first protocells. Coacervate droplets containing early forms of RNA seemed a natural next step.

What the researchers now showed in this new paper is that you can overcome at least part of that problem by transferring these coacervate droplets into distilled water—for example, rainwater or freshwater of any type—and they get a sort of tough skin around the droplets that restricts them from exchanging RNA content.

Where do you think distilled water could come from in a prebiotic world? Rain!

Working with RNA samples the researchers found that transferring coacervate droplets into distilled water increased the time scale of RNA exchange—from mere minutes to several days. This was long enough for mutation, competition, and evolution.

Part 1

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 8:14am

The researchers who developed this microscope based their work on the Nobel Prize-winning accomplishments of Pierre Agostini, Ferenc Krausz and Anne L'Huilliere, who won the Novel Prize in Physics in 2023 after generating the first extreme ultraviolet radiation pulse so short it could be measured in attoseconds.

Using that work as a steppingstone, the researchers developed a microscope in which a powerful laser is split and converted into two parts—a very fast electron pulse and two ultra-short light pulses. The first light pulse, known as the pump pulse, feeds energy into a sample and causes electrons to move or undergo other rapid changes.

The second light pulse, also called the "optical gating pulse" acts like a gate by creating a brief window of time in which the gated, single attosecond electron pulse is generated. The speed of the gating pulse therefore dictates the resolution of the image. By carefully synchronizing the two pulses, researchers control when the electron pulses probe the sample to observe ultrafast processes at the atomic level.
The electron movements happen in attoseconds. But now, for the first time, researchers are able to attain attosecond temporal resolution with their electron transmission microscope—and they coined it 'attomicroscopy.' For the first time, they could see pieces of the electron in motion.

Dandan Hui et al, Attosecond electron microscopy and diffraction, Science Advances (2024). DOI: 10.1126/sciadv.adp5805. www.science.org/doi/10.1126/sciadv.adp5805

Part 2

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 8:11am

Researchers develop world's fastest microscope that can see electrons in motion

Imagine owning a camera so powerful it can take freeze-frame photographs of a moving electron—an object traveling so fast it could circle the Earth many times in a matter of a second. Researchers have developed the world's fastest electron microscope that can do just that.

And they think their work will lead to groundbreaking advancements in physics, chemistry, bioengineering, materials sciences and more.

This transmission electron microscope is like a very powerful camera in the latest version of smart phones; it allows us to take pictures of things we were not able to see before—like electrons. With this microscope, the researchers hope the scientific community can understand the quantum physics behind how an electron behaves and how an electron moves.

A transmission electron microscope is a tool used by scientists and researchers to magnify objects up to millions of times their actual size in order to see details too small for a traditional light microscope to detect.

Instead of using visible light, a transmission electron microscope directs beams of electrons through whatever sample is being studied. The interaction between the electrons and the sample is captured by lenses and detected by a camera sensor in order to generate detailed images of the sample.

Ultrafast electron microscopes using these principles were first developed in the 2000's and use a laser to generate pulsed beams of electrons. This technique greatly increases a microscope's temporal resolution—its ability to measure and observe changes in a sample over time.

In these ultrafast microscopes, instead of relying on the speed of a camera's shutter to dictate image quality, the resolution of a transmission electron microscope is determined by the duration of electron pulses.

The faster the pulse, the better the image.

Ultrafast electron microscopes previously operated by emitting a train of electron pulses at speeds of a few attoseconds. An attosecond is one quintillionth of a second. Pulses at these speeds create a series of images, like frames in a movie—but scientists were still missing the reactions and changes in an electron that takes place in between those frames as it evolves in real time.

In order to see an electron frozen in place,  researchers, for the first time, generated a single attosecond electron pulse, which is as fast as electrons move, thereby enhancing the microscope's temporal resolution, like a high-speed camera capturing movements that would otherwise be invisible.

Part 1

Comment by Dr. Krishna Kumari Challa on August 21, 2024 at 11:17am

A legend in one's own mind: The link between ambition and leadership evaluations

Ambitious people aren't born leaders, research suggests

Do ambitious people make good leaders? Ambition can lead people to strive for leadership roles. But could there be a mismatch between qualities that motivate people to strive for leadership and qualities that make people good leaders?

asked 472 executives enrolled in a leadership development program offered by a West Coast business school in the United States to rate their ambition. The authors then compared these ambition scores with 360-degree leadership assessments obtained from the executives themselves, as well as their current managers, peers, and subordinates.

Thepaper is published in the journal PNAS Nexus.

The authors found, as expected, that leadership ambition increases self-ratings of effectiveness in a leadership role. That is, leaders with high self-reported ambition also rated themselves as highly-effective leaders. However, the authors found no relationship between leadership ambition and third-party ratings of leadership effectiveness; highly ambitious executives, compared to less ambitious executives, were rated as no more effective in their leadership roles by their managers, peers, or direct reports.

These results suggest that the pool of people striving for leadership roles may be filled with ambitious people who seek extrinsic rewards, such as high salaries and social status, and regard themselves more positively than others do. According to the authors, society may want to develop alternative approaches to choosing and training leaders.

More information: Shilaan Alzahawi et al, A legend in one's own mind: The link between ambition and leadership evaluations, PNAS Nexus (2024). DOI: 10.1093/pnasnexus/pgae295

Comment by Dr. Krishna Kumari Challa on August 21, 2024 at 11:04am

Research pinpoints how early-life antibiotics turn immunity into allergy

Researchers  have shown for the first time how and why the depletion of microbes in a newborn's gut by antibiotics can lead to lifelong respiratory allergies.

In a study published recently in the Journal of Allergy and Clinical Immunology, a research team from the school of biomedical engineering (SBME) has identified a specific cascade of events that lead to allergies and asthma. In doing so, they have opened many new avenues for exploring potential preventions and treatments.

This new research  finally shows how the gut bacteria and antibiotics shape a newborn's immune system to make them more prone to allergies.

Allergies are a result of the immune system reacting too strongly to harmless substances like pollen or pet dander, and a leading cause for emergency room visits in kids. Normally, the immune system protects us from harmful invaders like bacteria, viruses and parasites. In the case of allergies, it mistakes something harmless for a threat—in this case, parasites—and triggers a response that causes symptoms like sneezing, itching or swelling.

The stage for our immune system's development is set very early in life. Research over the past two decades has pointed toward microbes in the infant gut playing a key role. Babies often receive antibiotics shortly after birth to combat infections, and these can reduce certain bacteria. Some of those bacteria produce a compound called butyrate, which is key to halting the processes uncovered in this research.

The same researchers had previously shown that infants with fewer butyrate-producing bacteria become particularly susceptible to allergies. They had also shown that this could be mitigated or even reversed by providing butyrate as a supplement in early life.

Now, by studying the process in mice, they have discovered how this works.
Mice with depleted gut bacteria who received no butyrate supplement developed twice as many of a certain type of immune cell called ILC2s. These cells, discovered less than 15 years ago, have quickly become prime suspects in allergy development.

The researchers showed that ILC2s produce molecules that 'flip a switch' on white blood cells to make them produce an abundance of certain kinds of antibodies. These antibodies then coat cells as a defense against foreign invaders, giving the allergic person an immune system that is ready to attack at the slightest provocation.

Ahmed Kabil et al, Microbial intestinal dysbiosis drives long-term allergic susceptibility by sculpting an ILC2-B1 cell–innate IgE axis., Journal of Allergy and Clinical Immunology (2024). DOI: 10.1016/j.jaci.2024.07.023

Comment by Dr. Krishna Kumari Challa on August 21, 2024 at 10:36am

Gut microbial pathway identified as target for improved heart disease treatment

 Researchers have made a significant discovery about how the gut microbiome interacts with cells to cause cardiovascular disease. The study published in Nature Communications found that phenylacetylglutamine (PAG), produced by gut bacteria as a waste product, then absorbed and formed in the liver, interacts with previously undiscovered locations on beta-2 adrenergic receptors on heart cells once it enters the circulation.

PAG was shown to interact with beta-2 adrenergic receptors to influence how forcefully the heart muscle cells contract—a process that investigators think contributes to heart failure. Researchers showed mutating parts of the beta-2 adrenergic receptor that were previously thought to be unrelated to signaling activity in preclinical models prevented PAG from depressing the function of the receptor.

The same researchers earlier demonstrated that elevated circulating levels of PAG in subjects are associated with heightened risk for developing heart failure, and lead to worse outcomes for patients with heart failure.

They also showed that the gut microbial PAG signaling pathway was mechanistically linked to numerous heart failure-related features and cardiovascular disease risks. The new findings bring us one step closer to therapeutically targeting this pathway to develop an improved treatment for the prevention of heart failure.

 Prasenjit Prasad Saha et al, Gut microbe-generated phenylacetylglutamine is an endogenous allosteric modulator of β2-adrenergic receptors, Nature Communications (2024). DOI: 10.1038/s41467-024-50855-3

Comment by Dr. Krishna Kumari Challa on August 21, 2024 at 9:52am

Like many conspiracies, no researcher could come up with a mechanism. If dark matter and stars could interact in this way, then we would need to change our understanding of how galaxies form and evolve. But they also couldn't find an alternate reason to explain what they were seeing, until now.

Present research work found that the similarity in density might not be due to the galaxies themselves but in how astronomers were measuring and modeling them.

The team which made this observation observed 22 middle-aged galaxies (looking back some four billion years in the past due to their great distance) in extraordinary detail, using the European Southern Observatory's Very Large Telescope in Chile. It enabled them to create more complex models that better captured the diversity of galaxies in the universe.
In the past, people built simple models that had too many simplifications and assumptions. Galaxies are complicated, and researchers have to model them with freedom or they're going to measure the wrong things. The new models ran on the OzStar supercomputer at Swinburne University, using the equivalent of about 8,000 hours of desktop computing time.

C Derkenne et al, The MAGPI Survey: Evidence against the bulge-halo conspiracy, Monthly Notices of the Royal Astronomical Society (2024). DOI: 10.1093/mnras/stae1836

Part 2

**

Comment by Dr. Krishna Kumari Challa on August 21, 2024 at 9:49am

A galactic theory disproven: Dark matter and stars not interacting as previously thought

A longstanding theory in astronomy—that stars and dark matter are interacting in inexplicable ways—has been overturned by an international team of astronomers, in a paper in Monthly Notices of the Royal Astronomical Society.

The  theory emerged to explain a phenomenon that had puzzled astronomers for a quarter of a century. The density of matter in different galaxies appeared to be decreasing at the same rate from their center to outer edges. This was perplexing because galaxies are diverse, with many different ages, shapes, sizes, and numbers of stars. So why would they have the same density structure?

This homogeneity suggested that dark matter and stars must somehow compensate for each other in order to produce such regular mass structures.

Part 1

• ‹ Previous
• 1
• …
• 84
• 85
• 86
• 87
• 88
• …
• 999
• Next ›
• Page