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Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 12:56pm

How typhoid fever triggers severe neurological symptoms

Typhoid fever, caused by Salmonella Typhi, is one of the oldest documented human diseases. Most commonly spread by contaminated food or water, it is characterized by high fever, headaches, nausea, and, in some cases, potentially deadly neurological complications.

About 15% of patients with typhoid fever develop serious neurological complications, including delirium and seizures, that are collectively described as acute encephalopathy.

A new  study  published in the journal Nature Microbiology provides critical insights into how typhoid fever leads to encephalopathy. Researchers found that typhoid toxin, a key virulence factor only produced by the bacterium Salmonella Typhi, does not directly damage brain cells, as previously thought. Instead, it targets the endothelial cells lining the blood-brain barrier (BBB), causing significant barrier disruption and subsequent brain pathology.

The findings will inform treatment of this life-threatening infection, which annually afflicts about 12 million people and causes about 200,000 deaths, mostly in the world's poorest countries.

Researchers discovered that typhoid toxin severely damages the endothelial cells lining the BBB, a crucial protective barrier separating the bloodstream from the brain. This damage triggered inflammation, edema, and neurological dysfunction in mice models. Crucially, mice engineered to protect endothelial cells from toxin binding showed no neurological symptoms.

The team demonstrated that treatment with the corticosteroid dexamethasone effectively mitigated toxin-induced damage of the BBB and reduced brain inflammation and edema.

 Heng Zhao et al, Typhoid toxin causes neuropathology by disrupting the blood–brain barrier, Nature Microbiology (2025). DOI: 10.1038/s41564-025-02000-z

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 12:11pm

Flamingos are super-specialized animals for filter feeding. It's not just the head, but the neck, their legs, their feet and all the behaviors they use just to effectively capture these tiny and agile organisms.

 Victor M. Ortega-Jimenez et al, Flamingos use their L-shaped beak and morphing feet to induce vortical traps for prey capture, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2503495122

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 12:10pm

Flamingos create water tornados to trap their prey

Flamingos standing serenely in a shallow alkaline lake with heads submerged may seem to be placidly feeding, but there's a lot going on under the surface.

Through studies of Chilean flamingos in the Nashville Zoo and analysis of 3D printed models of their feet and L-shaped bills, researchers have documented how the birds use their feet, heads and beaks to create a storm of swirling tornados, or vortices, in the water to efficiently concentrate and slurp up their prey.

Part 1

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 12:01pm

Why so many microbes fail to grow in the lab

Microbial ecosystems—for example, in seawater, the soil or in the human gut—are astonishingly diverse, but researchers often struggle to reproduce this diversity in the lab: Many microorganisms die when attempts are made to cultivate them.

A new study by researchers offers fresh insights into this longstanding puzzle, suggesting that the survival of microbes does not depend solely on the needs of individual microbes but on a hidden web of relationships that can be caused to collapse by even small structural changes.

In work published in the Proceedings of the National Academy of Sciences, biodiversity experts  take a simplified view of microbial communities as a network based on cross-feeding, the exchange of metabolic by-products between populations. Each species needs nutrients and at the same time releases substances that are needed as food by others.

Scientists modeled this complex network by taking a novel approach. They used tools from network theory—a mathematical method developed by physicists—to understand the behavior of complex systems.

The result of the analysis: in the model, the loss of individual populations can cause the entire network to collapse, with the microbial community transitioning abruptly to a state of lower diversity. These collapses act as tipping points, resembling blackouts in power grids or supply chain breakdowns seen during the COVID-19 pandemic.

Trying to grow a microbial community in the laboratory is an example of such a perturbation according to the researchers. For example, if not all members of a natural microbial community are included in a sample, they will be missing as producers of metabolic products that are vital for other species. 

Although researchers have long suspected that the dependencies between microbes play a key role in our ability to grow them, this study is the first to show how this works across whole communities. The findings offer a new perspective on microbial resilience, highlighting how even in resource-rich environments like lab cultures, communities can fail if the networks of relationships are disrupted.

Tom Clegg et al, Cross-feeding creates tipping points in microbiome diversity, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2425603122

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 11:24am

After the amoeba ingests parts of human cells, it becomes resistant to a major component of the human immune system—a class of molecules called "complement proteins" that finds and kills invading cells.

In a new paper, posted to bioRxiv in October 2024, researchers found that the amoeba gains this resistance by ingesting proteins from the outer membranes of human cells and placing them on its own outer surface. Two of these human proteins, called CD46 and CD55, prevent complement proteins from latching onto the amoeba's surface.
In essence, the amoebae are killing human cells and then donning their protein uniforms as a disguise, allowing them to evade the human immune system.

This discovery can now be targeted to control this organism.

 Wesley Huang et al, Work with me here: variations in genome content and emerging genetic tools in Entamoeba histolytica, Trends in Parasitology (2025). DOI: 10.1016/j.pt.2025.03.010

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 11:20am

Parasitic amoeba kills human cells and wears their remains as disguise!

The single-celled parasite Entamoeba histolytica infects 50 million people each year, killing nearly 70,000. Usually, this wily, shape-shifting amoeba causes nothing worse than diarrhea. But sometimes it triggers severe, even fatal disease by chewing ulcers in the colon, liquefying parts of the liver and invading the brain and lungs.

It can kill anything you throw at it, any kind of human cell.

E. histolytica can even evade the immune system—and it can kill the white blood cells that are supposed to fight it.

E. histolytica enters the colon after a person ingests contaminated food or water.

Its species name, histolytica, means "tissue-dissolving"—because it creates festering pockets of liquefied tissue, called abscesses, in the organs it infects. As it rampages through a person's organs, it doesn't neatly eat the cells that it kills; instead, it leaves the wounded cells to spill out their contents while it hurries on to kill other cells.

As scientists watched it under a microscope 

But as she watched it through a microscope, they saw something very different.

E. histolytica was actually taking bites out of human cells. Peering through the microscope, you could see little parts of the human cell being broken off. Those ingested cell fragments, shining fluorescent green under their microscope, accumulated inside the amoeba.

 The report that the parasite kills cells through this process, called "trogocytosis," was published in the journal Nature in 2014

Part 1

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 11:11am

Lethal bacteria use sugar-sensing mechanism to recognize and infect cells

Scientists have discovered previously unknown molecular mechanisms that help a type of food-borne bacteria recognize host cells and initiate infection on the cell surface, according to a recent study published in Science Advances.

Multifunctional autoprocessing repeats-in-toxin (MARTX) toxins are secreted by bacteria and support the spread of many Gram-negative bacteria, including Vibrio vulnificus, a lethal food-borne bacterium commonly found in raw or undercooked shellfish.

MARTX toxins use precise intracellular mechanisms to infiltrate host cells and cause life-threatening infections.

In the current study, the investigators used a combination of cellular techniques to map the small portion of the large MARTX toxin from Vibrio vulnificus that directly interacts with the surface of cells.

The scientists found this domain binds N-acetylglucosamine (GlcNAc) (an amino sugar and key building block of complex glycans on the exposed surfaces of epithelial cells) to N-glycans (sugar molecules that decorate proteins on the surface of the host cell) with select preference for the L1CAM protein and clusters of N-glycans on host cell surfaces.

Different cell types have different kinds of sugars on them, and this is one way that toxins can discriminate one cell versus a different kind of cell.

The scientists also found that this domain is essential for Vibrio vulnificus infection during intestinal infection.

Jiexi Chen et al, Vibrio MARTX toxin binding of biantennary N-glycans at host cell surfaces, Science Advances (2025). DOI: 10.1126/sciadv.adt0063

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 10:53am

Gene mutations help flowers mimic foul odor to attract carcass-loving pollinators

A wild ginger has a clever trick up its sleeve to lure in pollinators. No, it's not a sweet fragrance that fills the air, but the foul stench of rotting flesh and dung. To attract carrion-loving flies and beetles, the flowers of the plant genus Asarum brew a malodorous chemical called dimethyl disulfide (DMDS) with the help of a disulfide synthase (DSS)—an enzyme derived from another enzyme, methanethiol oxidase (MTOX), found in both animals and plants.

A study by researchers  discovered that a few tweaks in a gene primarily responsible for detoxifying smelly compounds have independently evolved in three different plant lineages to produce unpleasant odors.

The same three amino acid changes, found in all the independently evolved DSS enzymes, enabled the transition from MTOX to DSS activity, according to the research published in Science.

Yudai Okuyama, Convergent acquisition of disulfide-forming enzymes in malodorous flowers, Science (2025). DOI: 10.1126/science.adu8988. www.science.org/doi/10.1126/science.adu8988

Lorenzo Caputi, Flowers with bad breath, Science (2025). DOI: 10.1126/science.adx4375. www.science.org/doi/10.1126/science.adx4375

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 10:30am

Antibiotics from human use are contaminating rivers worldwide, study shows

Millions of kilometers of rivers around the world are carrying antibiotic pollution at levels high enough to promote drug resistance and harm aquatic life, a new study warns.

Published in PNAS Nexus, the study is the first to estimate the scale of global river contamination from human antibiotics use. Researchers calculated that about 8,500 tons of antibiotics—nearly one-third of what people consume annually—end up in river systems around the world each year even after, in many cases, passing through wastewater systems.

While the amounts of residues from individual antibiotics translate into only very small concentrations in most rivers, which makes them very difficult to detect, the chronic and cumulative environmental exposure to these substances can still pose a risk to human health and aquatic ecosystems.

The research team used a global model validated by field data from nearly 900 river locations. They found that amoxicillin, the world's most-used antibiotic, is the most likely to be present at risky levels. 

The study, however,  did not consider antibiotics from livestock or pharmaceutical factories, both of which are major contributors to environmental contamination.

Heloisa Ehalt Macedo et al, Antibiotics in the global river system arising from human consumption, PNAS Nexus (2025). DOI: 10.1093/pnasnexus/pgaf096

Comment by Dr. Krishna Kumari Challa on May 13, 2025 at 9:35am

The researchers did the calculations dead-seriously and the basis is a reinterpretation of Hawking radiation.
In 1975, physicist Stephen Hawking postulated that contrary to the theory of relativity, particles and radiation could escape from a black hole. At the edge of a black hole, two temporary particles can form, and before they merge, one particle is sucked into the black hole and the other particle escapes.

One of the consequences of this so-called Hawking radiation is that a black hole very slowly decays into particles and radiation. This contradicts Albert Einstein's theory of relativity, which says that black holes can only grow.
The researchers calculated that the process of Hawking radiation theoretically also applies to other objects with a gravitational field. The calculations further showed that the evaporation time of an object depends only on its density.

To the researchers' surprise, neutron stars and stellar black holes take the same amount of time to decay: 1067 years. This was unexpected because black holes have a stronger gravitational field, which should cause them to evaporate faster.

But black holes have no surface. They reabsorb some of their own radiation which inhibits the process.

 H. Falcke et al, An upper limit to the lifetime of stellar remnants from gravitational pair production, Journal of Cosmology and Astroparticle Physics. On arXiv (2024). DOI: 10.48550/arxiv.2410.14734

Part 2

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