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Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 9:49am

Mechanism for removing dead cells identified

Billions of our cells die every day to make way for the growth of new ones. Most of these goners are cleaned up by phagocytes—mobile immune cells that migrate where needed to engulf problematic substances. But some dying or dead cells are consumed by their own neighbors, natural tissue cells with other primary jobs. How these cells sense the dying or dead around them has been largely unknown till now.

Now researchers from The Rockefeller University have shown how a sensor system operates in hair follicles, which have a well-known cycle of birth, decay, and regeneration put into motion by hair follicle stem cells (HFSCs). In a new study published in Nature, they demonstrate that a duo of sensors works in tandem to pick up signals from both dying and living HFSCs, removing debris before tissue damage can occur and ceasing operation before healthy cells are consumed.

The system is seemingly spatially tuned to the presence of corpses, and it only functions when each receptor picks up the signal is attuned to. If one of them disappears, the mechanism stops operating. It's a really beautiful way to keep the area clean without consuming healthy cells.

By diverting their attention towards eating their dying neighbors, HFSCs keep inflammation-generating immune cells away. They also likely benefit from these extra calories, but as soon as the debris is cleared, they must quickly return to their jobs of maintaining the stem cell pool and making the body's hair.

Part 1

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 9:44am

Study finds 'DNA scavengers' can stop some antibiotic resistance from spreading

For nearly a century, scientists have waged war on antibiotic-resistant microbes. Researchers now found a new way to prevent it—by unleashing "DNA scavengers" in wastewater treatment plants.

They found an enzyme that breaks up strands of antibiotic-resistant DNA floating in wastewater before bacteria can pick them up and take on their antibiotic-resistant properties. 

This could be a powerful, environmentally friendly tool to control the spread of antibiotic resistance in wastewater and help keep antibiotics effective.

But as with any new discovery, there is more work to be done to optimize the technology.

Yang Li et al, Engineered DNA scavenger for mitigating antibiotic resistance proliferation in wastewater treatment, Nature Water (2024). DOI: 10.1038/s44221-024-00289-4

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 9:36am

The research that was done on a mouse model showed that Salmonellae detect electric signals in FAE. They move toward this part of the gut where they find openings through which they can enter. This process of cell movement in response to electric fields is called galvanotaxis, or electrotaxis.

This study found that this 'entry point' has electric fields that the Salmonella bacteria take advantage of to pass.

The study also showed that E. coli and Salmonella respond differently to bioelectric fields. They have opposite responses to the same electric cue. While E. coli clustered next to the villi, Salmonella gathered to FAE.

The study detected electric currents that loop by entering the absorptive villi and exiting the FAE.

Notably, the bioelectric field in the gut epithelia is configured in a way that Salmonellae take advantage of to be sorted to the FAE and less so for E. coli. The pathogen seems to prefer the FAE as a gateway to invade the host and cause infections.

Previous studies have indicated that bacteria use chemotaxis to move around. With chemotaxis, the bacteria sense chemical gradients and move towards or away from specific compounds. But the new study suggests that the galvanotaxis of Salmonella to the FAE does not occur through chemotaxis pathways.

The study might have the potential to explain complex chronic diseases, such as inflammatory bowel disease (IBD).

This mechanism represents a new pathogen-human body 'arms race' with potential implications for other bacterial infections as well as prevention and treatment possibilities. It is thought that the root cause of IBD is an excessive and abnormal immune response against good bacteria. It will be interesting to learn whether patients prone to have IBD also have aberrant bioelectric activities in gut epithelia.

Yao-Hui Sun et al, Gut epithelial electrical cues drive differential localization of enterobacteria, Nature Microbiology (2024). DOI: 10.1038/s41564-024-01778-8

Part 2

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 9:32am

Study discovers an electric current in the gut that attracts pathogens like Salmonella
How do bad bacteria find entry points in the body to cause infection? This question is fundamental for infectious disease experts and people who study bacteria. Harmful pathogens, like Salmonella, find their way through a complex gut system where they are vastly outnumbered by good microbes and immune cells. Still, the pathogens navigate to find vulnerable entry points in the gut that would allow them to invade and infect the body.

A team of researchers has discovered a novel bioelectrical mechanism these pathogens use to find these openings. Their study was published  in Nature Microbiology.

Salmonella cause  several illnesses and  deaths in the world every year. To infect someone, this pathogen needs to cross the gut lining border.

When ingested, Salmonella find their way to the intestines. There, they are vastly outnumbered by over 100 trillion good bacteria (known as commensals). They are facing the odds of one in a million. But still they can infect people. 

The intestine has a very complex landscape. Its epithelial structure includes villus epithelium and follicle-associated epithelium (FAE). Villus epithelium is made of absorptive cells (enterocytes) with protrusions that help with nutrient absorption.

FAE, on the other hand, contains M cells overlying small clusters of lymphatic tissue known as Peyer's patches. These M cells are tasked with antigen sampling. They act as the immune system's first line of defense against microbial and dietary antigens.

Part 1

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 9:23am

Human-wildlife overlap expected to increase across more than half of land on Earth by 2070

As the human population grows, more than half of Earth's land will experience an increasing overlap between humans and animals by 2070, according to a new study by scientists.

Greater human-wildlife overlap could lead to more conflict between people and animals, say the researchers. But understanding where the overlap is likely to occur—and which animals are likely to interact with humans in specific areas—will be crucial information for urban planners, conservationists and countries that have pledged international conservation commitments. Their findings are published in Science Advances.

They found that the overlap between populations of humans and wildlife will increase across about 57% of the global lands, but it will decrease across only about 12% of the global lands. They  also found that agricultural and forest areas will experience substantial increases of overlap in the future.

The study showed that the human-wildlife overlap will be driven by human population growth rather than climate change. That is, the increase in people settling in previously undeveloped areas will drive the overlap rather than climate change, causing animals to shift where they live.

In many places around the world, more people will interact with wildlife in the coming decades and often those wildlife communities will comprise different kinds of animals than the ones that live there now.

This means that all sorts of novel interactions, good and bad, between people and wildlife will emerge in the near future.

Deqiang Ma et al, Global Expansion of Human-Wildlife Overlap in the 21st Century, Science Advances (2024). DOI: 10.1126/sciadv.adp7706. www.science.org/doi/10.1126/sciadv.adp7706

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 9:18am

Bacteria make thermally stable plastics similar to polystyrene and PET for the first time

Bioengineers around the world have been working to create plastic-producing microbes that could replace the petroleum-based plastics industry. Now, researchers  have overcome a major hurdle: getting bacteria to produce polymers that contain ring-like structures, which make the plastics more rigid and thermally stable.

Because these molecules are usually toxic to microorganisms, the researchers had to construct a novel metabolic pathway that would enable the E. coli bacteria to both produce and tolerate the accumulation of the polymer and the building blocks it is composed of.

The resulting polymer is biodegradable and has physical properties that could lend it to biomedical applications such as drug delivery, though more research is needed. The results are presented August 21 in Trends in Biotechnology.

Microbial Production of an Aromatic Homo-Polyester, Trends in Biotechnology (2024). DOI: 10.1016/j.tibtech.2024.06.001

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 9:13am

Self-repairing mitochondria use novel recycling system, study finds

Mitochondria depend on a newly discovered recycling mechanism identified by scientists.

Mitochondria are tiny structures inside of cells that carry out a wide range of critical functions, including generating energy to help keep cells healthy. Every mitochondrion has two layers of membranes: the outer membrane and the inner membrane. On the inner membrane, folds called cristae contain proteins and molecules needed for energy production. When cristae are damaged, there can be a negative impact on an entire cell.

This new research work  shows, for the first time, that mitochondria are able to recycle a localized injury, removing damaged cristae, and then function normally afterward.

In addition to being essential to keeping mitochondria healthy, the research team thinks this mechanism could present a future target for the diagnosis and treatment of conditions characterized by mitochondrial dysfunction, including infection, fatty liver disease, aging, neurodegenerative conditions and cancer.

In cells, structures called lysosomes act as recycling centers that can digest different kinds of molecular material. With state-of-the art microscopes the researchers  identified that a mitochondria's damaged crista can squeeze through its outer membrane to have a lysosome directly engulf it and break it down successfully.

The researchers named the novel process VDIM formation, which stands for vesicles derived from the inner mitochondrial membrane. By removing damaged cristae through VDIMs, cells can prevent harm from spreading to the rest of the mitochondria and the whole cell.

Forming a VDIM involved several steps and molecules.

First, a damaged crista releases a signal that activates a channel on the nearby lysosome to allow calcium to flow out of the lysosome.

Calcium then activates another channel on the outer membrane of the mitochondria to form a pore and allow damaged cristae to squeeze out of the mitochondria into the lysosome, which digests the damaged material—something that has never been seen before. By recycling just the damaged crista, mitochondria can continue its regular function.

Understanding this process gives us insight into how mitochondria stay healthy, which is important to everyone's overall health and longevity.

Nicola Jones et al, Lysosomes drive the piecemeal removal of mitochondrial inner membrane, Nature (2024). DOI: 10.1038/s41586-024-07835-w. www.nature.com/articles/s41586-024-07835-w

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 8:56am

Researchers train a robot dog to combat invasive fire ants

A multidisciplinary research team based across China and Brazil has used a dog-like robot and AI to create a new way to find fire ant nests. Published in the journal Pest Management Science, the study highlights how a "CyberDog" robot integrated with an AI model can automate the identification and control of Red Imported Fire Ants (RIFA), a globally destructive pest.

Field tests carried out by the researchers reveal the robotic system can significantly outperform human inspectors, identifying three times more RIFA nests with greater precision.

Fire ant nests are difficult for untrained personnel to identify and confirm in the field, and searching large areas can be time-consuming and exhausting under the hot sun. A robot could automatically locate the nests without requiring specially trained individuals and operate at various times of the day regardless of temperature conditions.

They conducted rigorous field tests to measure the system's effectiveness. The CyberDog was programmed to press the nest with its front paw: when a fire ant nest mound is disturbed, the workers will rush out from cracks and openings displaying aggressive behavior. This, the researchers said, is key for diagnosing active mounds from abandoned nests, and to avoid false positives with mounds inhabited by other species.

The implementation of robotic dogs in automatic detection and surveillance of red imported fire ant nests, Pest Management Science (2024). DOI: 10.1002/ps.8254

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 8:51am

This simple schematic shows how the Wow! Signal was generated and detected. A radiative source such as a magnetar or a soft gamma repeater is positioned behind a cloud of cold neutral hydrogen. Energy from the source stimulates emission from the HI cloud, which brightens abruptly and is observable from Earth. Credit: arXiv (2024). DOI: 10.48550/arxiv.2408.08513

Part 3

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 8:48am

The researchers hypothesize that the Wow! Signal was caused by sudden brightening from stimulated emission of the hydrogen line due to a strong transient radiation source, such as a magnetar flare or a soft gamma repeater (SGR)," they write. Those events are rare and rely on precise conditions and alignments. They can cause clouds of hydrogen to brighten considerably for seconds or even minutes.

The researchers say that what Big Ear saw in 1977 was the transient brightening of one of several H1 (neutral hydrogen) clouds in the telescope's line of sight. The 1977 signal was similar to what the researchers saw now in many respects. The only difference between the signals observed now and the Wow! Signal is their brightness. It is precisely the similarity between these spectra that suggests a mechanism for the origin of the mysterious signal," the authors write.
These signals are rare because the spatial alignment between source, cloud, and observer is rare. The rarity of alignment explains why detections are so rare.
The new hypothesis explains all observed properties of the Wow! Signal, proposes a new source of false positives in technosignature searches, and suggests that the Wow! Signal could be the first recorded event of an astronomical maser flare in the hydrogen line," the authors explain in their conclusion.

 Abel Méndez et al, Arecibo Wow! I: An Astrophysical Explanation for the Wow! Signal, arXiv (2024). DOI: 10.48550/arxiv.2408.08513

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