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Comment by Dr. Krishna Kumari Challa on August 24, 2024 at 9:56am

Micro- and nanoplastics ingested by Drosophila cause changes in heart size and function

Plastics are ubiquitous in products we use every day, and recent studies have begun to reveal the effects of micro- and nanoplastics (MPs and NPs) on the health of humans and animals.

Much research on the health effects of MPs and NPs to date has focused on marine life, especially fish. A few early studies have investigated possible toxic effects of plastics on terrestrial species such as birds, earthworms, insects, humans and other mammals, but myriad specifics remain unknown.

A team of researchers from Iowa State University, using fruit flies (Drosophila melanogaster), has now made the first examination of the effects of MP and NP toxicity on the heart. The team's work is published in a Brief Research Report in Frontiers in Toxicology.

Drosophila hearts and vertebrate hearts are similar with respect to functional and genetic changes during development and aging. For this new study, the researchers obtained wild-type Drosophila fly larvae and divided them into a control group and two test groups.
They fed all the flies a diet of cornmeal from the beginning of their development until they reached maturity (pupation). Flies in the two test groups received cornmeal to which the researchers added polystyrene MPs (larger than 100 nm and smaller than 5 mm) or NPs (smaller than 100 nm).

Five days after the flies hatched, the researchers collected approximately 15 flies of each sex from each of the two test groups and the control group. The team anesthetized the flies, dissected their beating hearts, and recorded high-speed video at over 200 frames/second for analysis.

Among the notable results, the analysis indicates that plastic exposure produces different results in males and females. The heart rates of female flies exposed to both MPs and NPs decreased 13%, while their heart periods (time between the beginning of a heartbeat and the beginning of the next heartbeat) increased correspondingly. Male flies did not exhibit this change, but males fed MPs exhibited greater variability than those fed NPs and those in the control group.
Part 1

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 11:04am

‘Dark Oxygen’ Is Coming from These Ocean Nodules

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 10:18am

The blue light theory involves melatonin, a hormone that regulates sleep. During the day, we are exposed to bright, natural light that contains a high amount of blue light. This bright, blue light activates certain cells at the back of our eyes, which send signals to our brain that it's time to be alert. But as light decreases at night, our brain starts to produce melatonin, making us feel sleepy.

It's logical to think that artificial light from devices could interfere with the production of melatonin and so affect our sleep. But studies show it would require light levels of about 1,000–2,000 lux (a measure of the intensity of light) to have a significant impact.

Device screens emit only about 80–100 lux. At the other end of the scale, natural sunlight on a sunny day provides about 100,000 lux.

We know that bright light does affect sleep and alertness. However, research indicates the light from devices such as smartphones and laptops is nowhere near bright or blue enough to disrupt sleep.
There are many factors that can affect sleep, and bright, blue screen light likely isn't one of them.

Part 2

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 10:06am

How much does your phone's blue light really delay your sleep? Relax, it's just 2.7 minutes!

It's one of the most pervasive messages about technology and sleep. We're told bright, blue light from screens prevents us falling asleep easily. We're told to avoid scrolling on our phones before bedtime or while in bed. We're sold glasses to help filter out blue light. We put our phones on "night mode" to minimize exposure to blue light.

But what does the science actually tell us about the impact of bright, blue light and sleep? When a group of sleep experts from Sweden, Australia and Israel compared scientific studies that directly tested this, they   found the overall impact was close to meaningless. Sleep was disrupted, on average, by less than three minutes.

Scientists showed the message that blue light from screens stops you from falling asleep is essentially a myth, albeit a very convincing one.

Instead, they found a more nuanced picture of technology and sleep.

https://www.sciencedirect.com/science/article/pii/S1087079224000376...

Part 1

Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 10:01am

Mother's gut microbiome during pregnancy shapes baby's brain development, mouse study finds

A study in mice has found that the bacteria Bifidobacterium breve in the mother's gut during pregnancy supports healthy brain development in the fetus. The results are published in the journal Molecular Metabolism.

Researchers have compared the development of the fetal brain in mice whose mothers had no bacteria in their gut, to those whose mothers were given Bifidobacterium breve orally during pregnancy, but had no other bacteria in their gut.

Nutrient transport to the brain increased in fetuses of mothers given Bifidobacterium breve, and beneficial changes were also seen in other cell processes relating to growth.

Bifidobacterium breve is a 'good bacteria' that occurs naturally in our gut, and is available as a supplement in probiotic drinks and tablets.

Obesity or chronic stress can alter the gut microbiome of pregnant women, often resulting in fetal growth abnormalities. The babies of up to 10% of first-time mothers have low birth weight or fetal growth restriction. If a baby hasn't grown properly in the womb, there is an increased risk of conditions like cerebral palsy in infants and anxiety, depression, autism, and schizophrenia in later life.

These results suggest that improving fetal development—specifically fetal brain metabolism—by taking Bifidobacterium breve supplements while pregnant may support the development of a healthy baby.

Previous work by the same team of researchers found that treating pregnant mice with Bifidobacterium breve improves the structure and function of the placenta. This also enables a better supply of glucose and other nutrients to the developing fetus and improves fetal growth.

Although further research is needed to understand how these effects translate to humans, this exciting discovery may pave the way for future clinical studies that explore the critical role of the maternal microbiome in supporting healthy brain development before birth.

Jorge Lopez-Tello et al, Maternal gut Bifidobacterium breve modifies fetal brain metabolism in germ-free mice, Molecular Metabolism (2024). DOI: 10.1016/j.molmet.2024.102004

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Comment by Dr. Krishna Kumari Challa on August 22, 2024 at 9:51am

To initiate the process, hair follicle stem cells (HFSCs), located in the "bulge" of the follicle's upper root sheath, signal to epithelial and mesenchymal cells, sparking growth. This stage takes its time, lasting from two to six years.

The destructive, or catagen, stage that follows is brief but intense, obliterating about 80% of the hair follicle in just a few weeks. The process begins at the follicle base and works its way upwards towards the HFSC niche. The result is a mass of dying and dead cells that need removal to prevent the resulting decay from triggering inflammatory or autoimmune responses.

Normally, this would be the job of phagocytes like macrophages, but few are found in the hair follicle, meaning they must fall to local epithelial cells to keep things tidy.

 Elaine Fuchs, Stem cells tightly regulate dead cell clearance to maintain tissue fitness, Nature (2024). DOI: 10.1038/s41586-024-07855-6. www.nature.com/articles/s41586-024-07855-6

Part 2

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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.

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