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Comment by Dr. Krishna Kumari Challa on October 23, 2023 at 9:30am

Two probiotics identified as promising hypertension treatments

An estimated 40% of the global adult population have high blood pressure, or hypertension, which puts people at risk of cardiovascular disease and other dangerous health conditions. Recent studies suggest that probiotics may offer a protective effect, but researchers have a limited understanding of why shaping the gut microbiota can regulate blood pressure.

A study published in mSystems adds two new strains to the list of potential antihypertensive probiotics.

In experiments on hypertensive mice, treatment with the two probiotics, Bifidobacterium lactis and Lactobacillus rhamnosus, returned blood pressure to normal levels. The researchers also tracked how those probiotics altered the animals' gut microbial mix over 16 weeks, identifying specific microbes and metabolic pathways that may help explain the protective effect.

Accumulated evidence supports an antihypertensive effect of probiotics and probiotic fermented foods in both in vitro and in vivo experiments

Previous studies have connected the rising rates of hypertension worldwide to increasing consumption of sugar. It likely boosts blood pressure through many mechanisms—increased insulin resistance or salt retention, for example—but in recent years researchers have investigated sugar's effect on the gut microbiome, as well.

In the new study, the researchers tested the two probiotic strains on mice that developed high blood pressure after consuming water mixed with fructose. Over 16 weeks, they measured the animals' blood pressures every four weeks. They found that fructose-fed mice that received either probiotic showed significantly lower blood pressures than those fed a high fructose diet and not treated with probiotics.

The researchers used shotgun metagenomic sequencing to probe connections between the altered gut microbiota and the change in blood pressure. They found that a high-fructose diet in the mice led to an increase in Bacteroidetes and a decrease in Firmicutes bacteria; however, treatment with probiotics returned those populations to those found in the control group. In addition, the analysis identified new microbial signatures associated with blood pressure: Increased levels of Lawsonia and Pyrolobus bacteria, and reduced levels of Alistipes and Alloprevotella, were associated with lower blood pressure.

 mSystems (2023). journals.asm.org/doi/10.1128/msystems.00331-23

Comment by Dr. Krishna Kumari Challa on October 22, 2023 at 9:03am

The encounter between Neanderthals and Homo sapiens as told by their genomes

 About 40,000 years ago, Neanderthals, who had lived for hundreds of thousands of years in the western part of the Eurasian continent, gave way to Homo sapiens, who had arrived from Africa. This replacement was not sudden, and the two species coexisted for a few millennia, resulting in the integration of Neanderthal DNA into the genome of Homo sapiens.

Researchers  have analyzed the distribution of the portion of DNA inherited from Neanderthals in the genomes of humans (Homo sapiens) over the last 40,000 years. These statistical analyses revealed subtle variations in time and geographical space. This work, published in the journal Science Advances, helps us to understand the common history of these two species.

Thanks to genome sequencing and comparative analysis, it is established that Neanderthals and Homo sapiens interbred and that these encounters were sometimes fruitful, leading to the presence of about 2% of DNA of Neanderthal origin in present-day Eurasians. However, this percentage varies slightly between regions of Eurasia, since DNA from Neanderthals is somewhat more abundant in the genomes of Asian populations than in those of European populations.

One hypothesis to explain this difference is that natural selection would not have had the same effect on genes of Neanderthal origin in Asian and European populations.

Another new theory suggests that such differences could be explained by migratory flows: when a migrant population hybridizes with a local population, in their area of cohabitation, the proportion of DNA of the local population tends to increase with distance from the point of departure of the migrant population.

In the case of Homo sapiens and Neanderthals, the hypothesis is that the further one moves away from Africa, Homo sapiens' point of origin, the greater the proportion of DNA from Neanderthal, a population mainly located in Europe. To test this hypothesis, the authors used a database made available by Harvard Medical School that includes more than 4,000 genomes from individuals who have lived in Eurasia over the past 40 millennia.

Statistical analyses revealed that, in the period following the dispersal of Homo sapiens from Africa, the genomes of Paleolithic hunter-gatherers who lived in Europe contained a slightly higher proportion of DNA of Neanderthal origin than the genomes of those who lived in Asia. This result is contrary to the current situation but in agreement with paleontological data, since the presence of Neanderthals was mainly reported in western Eurasia (no Neanderthal bones have been discovered further east than the Altai region of Siberia).

Subsequently, during the transition to the Neolithic, i.e. the transition from the hunter-gatherer lifestyle to the farmer lifestyle, 10,000 to 5,000 years ago, the study shows a decline in the proportion of DNA of Neanderthal origin in the genomes of European populations, resulting in a slightly lower percentage than that of Asian populations (as currently observed).

This study shows that the analysis of ancient genomes, coupled with archaeological data, makes it possible to trace different stages in the history of hybridized species.

Claudio S. Quilodrán, Jérémy Rio, Alexandros Tsoupas, Mathias Currat. Past human expansions shaped the spatial pattern of Neanderthal ancestry. Science Advances, 2023; 9 (42) DOI: 10.1126/sciadv.adg9817

Comment by Dr. Krishna Kumari Challa on October 21, 2023 at 11:47am

The researchers demonstrated that there were considerable differences in gene expression in the intestine, brain and placenta of the fetuses of germ-free and normal mouse dams.

In the gut, genes associated with the immune system and host–microbe interactions were less active in the fetuses of germ-free dams. There were significant differences in the expression of genes in the brain associated with the development and functioning of the nervous system. In the placenta, there were differences in the expression of several important genes that regulate pregnancy.

The differences were more extensive in male fetuses, indicating that they may be more sensitive to the effects of the maternal microbiota, at least in mice.

The researchers discovered that the expression of many important genes was associated with the concentration of metabolites likely to be modulated by the maternal microbiota. These metabolites were absent in the fetuses of germ-free dams, or occurred at least at significantly lower concentrations.

Aleksi Husso et al, Impacts of maternal microbiota and microbial metabolites on fetal intestine, brain, and placenta, BMC Biology (2023). DOI: 10.1186/s12915-023-01709-9

Part 2

Comment by Dr. Krishna Kumari Challa on October 21, 2023 at 11:46am

Maternal microbiota can affect fetal development

In a new study, significant differences in the gene activity of the faetal intestine, brain and placenta were identified, depending on the microbes in the mother's body and the compounds produced by them. The findings indicate that maternal microbes are important to her offspring's development and health.

The microbiota of the mother, or dam, is thought to be important for the development and health of her offspring. However, so far little is known about how interactions with the microbiota begin and what the mechanisms of action are.

A collaborative study investigated how the maternal microbiota affects fetal development by comparing the fetuses of normal and germ-free mouse dams living in a sterile environment. The researchers measured gene expression and the concentrations of small-molecular compounds, or metabolites, in the fetal intestine, brain and placenta.

This new  study sheds light on the significance of the microbiota and the mechanisms by which the microbiota affects individual development and pregnancy. Researchers identified previously unknown compounds in the fetus, which are likely to be microbial, and which can be important for individual development.

Part 1

Comment by Dr. Krishna Kumari Challa on October 21, 2023 at 11:26am

Meiosis, the cell division process giving rise to sperm and eggs, involves several steps, one of which is the formation of a large protein structure called the synaptonemal complex. Like a bridge, the complex holds chromosome pairs in place enabling necessary genetic exchanges to occur that are essential for the chromosomes to then correctly separate into sperm and eggs.

A significant contributor to infertility is defects in meiosis.  what happens right before that when the synaptonemal complex forms between the daughter reproductive cells .

Previous studies have examined many proteins comprising the synaptonemal complex, how they interact with each other, and have identified various mutations linked to male infertility. The protein the researchers investigated in this study forms the lattices of the proverbial bridge, which has a section found in humans, mice, and most other vertebrates suggesting it is critical for assembly. Modeling different mutations in a potentially crucial region in the human protein enabled the team to predict which of these might disrupt protein function.

The authors used a precise gene editing technique to make mutations in one key synaptonemal complex protein in mice, which allowed the researchers, for the first time, to test the function of key regions of the protein in live animals. Just a single mutation, predicted from the modeling experiments, was verified as the culprit of infertility in mice.

Katherine Billmyre et al, SYCP1 head-to-head assembly is required for chromosome synapsis in mouse meiosis, Science Advances (2023). DOI: 10.1126/sciadv.adi1562. www.science.org/doi/10.1126/sciadv.adi1562

Part 2

Comment by Dr. Krishna Kumari Challa on October 21, 2023 at 11:21am

Why do some men not produce sperm? Scientists uncover one underlying reason for male infertility

Millions of couples worldwide experience infertility with half of the cases originating in men. For 10% of infertile males, little or no sperm are produced. Now, new research is shedding light on what may be going wrong in the process of sperm formation, leading to potential theories on possible treatments.

In most sexually-reproducing species, including humans, a critical protein structure resembling a lattice-like bridge needs to be built properly to produce sperm and egg cells. The team  discovered that in mice, changing a single and very specific point in this bridge caused it to collapse, leading to infertility and thus providing insight into human infertility in males due to similar problems with meiosis.

Part 1

Comment by Dr. Krishna Kumari Challa on October 21, 2023 at 11:03am

Microbiome facts
There are trillions of microbes living inside and on the surface of your body; together they are called the microbiome and they are vital to your health and fighting disease.
Since the microbiome was first recognized in the late 1990s, scientists have identified more than 2,000 microbial species from the largest microbiome, in the gut.
The skin, bladder and genitals also harbor microbiome populations.
Your gut microbiome composition is unique to you and effects your metabolism, gastrointestinal tract, brain, and immune system.
In a healthy person, the symbiotic and pathogenic microbes work in balance.
Imbalances between symbiotic (benefiting you and the microbes) and pathogenic (disease-causing) microbes, known as dysbiosis, disrupt the microbes, making people more susceptible to conditions such as inflammatory bowel disease (IBD) and Clostridioides difficile infection, which causes severe diarrhea and inflammation of the colon or colitis.
There is hope that we may soon be on the cusp of a new era of health care that nurtures and tweaks the microbiome to optimize human health.

Disease-specific loss of microbial cross-feeding interactions in the human gut, Nature Communications (2023). DOI: 10.1038/s41467-023-42112-w

Part 2

Comment by Dr. Krishna Kumari Challa on October 21, 2023 at 11:02am

Deep dive into the gut unlocks new disease treatments

The more diverse species in your gut, the better it is for your health. Now an international team has found a way to determine which species are important and how they interact to create a healthy microbiome.

Understanding these relationships opens the door to a new world of medical opportunities for conditions from inflammatory bowel disease to infections, autoimmune diseases and cancers.

There are roughly 1,000 different bacterial species in a healthy gut—it's a microscopic multicultural community with over a trillion individual members.

Bacteria in our microbiomes exist as communities that rely on each other to produce and share key nutrients between them.

Researchers have developed a new computational way to understand these dependencies and their role in shaping human microbiome. This new method unlocks our understanding of the gut microbiome and provides a foundation for new treatment options that selectively remodel microbial communities.

For example, in Crohn's Disease, the team confirmed the importance of hydrogen sulfide. They discovered that the most likely cause is loss of bacteria that use hydrogen sulfide, not an increase in species producing it, as was previously thought. 

This is a significant step in the development of complex microbial therapies. This approach allows us to identify and rank the key interactions between bacteria and use this knowledge to predict targeted ways to change the community.

Part 1

Comment by Dr. Krishna Kumari Challa on October 21, 2023 at 9:46am

New study shows Hunga-Tonga Hunga-Ha'apai eruption depleted ozone layer

A large team of atmospheric specialists has found that when the Hunga-Tonga Hunga-Ha'apai volcano erupted last year, it took part of the ozone layer with it. Their findings are published in the journal Science.

Prior research has shown that the Hunga-Tonga Hunga-Ha'apai eruption was one of the more powerful explosions ever recorded. It was also unique in that instead of spewing just volcanic material, dirt and rocks, it also sent a very large amount of ocean water into the atmosphere. In this new effort, the research team have found that all that saltwater reacting with other chemicals in the atmosphere, resulted in breaking down O₃ in the ozone layer.

To learn more about the impact of the eruption, the researchers sent balloons with sensors into the atmosphere from nearby Réunion Island just five days after the volcano erupted. In studying the data from the sensors, the researchers found that ozone levels in the plume were approximately 30% below normal levels.

As the balloons continued to monitor the plume as it floated across the Indian and then Pacific Ocean, they found depletion totals of approximately 5%. The depletion, they found was due to ocean water reacting with molecules in the atmosphere that contained chlorine, leading to a breakdown of ozone—in amounts that had never been seen before in such a short time.

 Stephanie Evan et al, Rapid ozone depletion after humidification of the stratosphere by the Hunga Tonga Eruption, Science (2023). DOI: 10.1126/science.adg2551

Comment by Dr. Krishna Kumari Challa on October 21, 2023 at 9:33am

10 billion snow crabs starved to death in the Bering Sea because ...

A team of marine biologists has solved the mystery of why approximately 10 billion snow crabs vanished from the Bering Sea back in 2018/2019—the water there was too warm for them!

In their study, reported in the journal Science, the group used data from previous studies on the way snow crabs respond to warmer temperatures to solve the mystery.

Snow crabs are relatively small crabs, that, despite their name, are not white—they are red, like lobsters. They live on the ocean floor in shallow areas and have been consumed as a seafood delicacy for many years.

Alaskan fishermen (and scientists) first noticed a dramatic decline in their numbers back in 2021. Then, due to the pandemic, fishing and studying of the crabs was put on hiatus for a year. The full extent of the crab disappearance was only observed earlier in 2023—over 10 billion were missing. Upon discovering this alarming decline, a research team set to work to figure out what happened.

The team started by scouting nearby areas, hoping that the crabs had simply moved to another location, but no sign of them could be found. Next, noting that the area had experienced a heat wave prior to, and during, the crab disappearance they turned to the results of a prior study that had found that when water temperatures increase, energy requirements for the crabs increase. The researchers found that if water temperatures increased by just 3°C, the caloric needs of the crabs doubled.

Records showed that during the heat wave, water temperatures had risen 3°C, which meant the crabs would have needed twice as much food to sustain themselves. The research team also found that just prior to the heat wave, the crab population had risen dramatically, meaning that there had been a large increase in competition for food. And that, the researchers conclude, led the crabs to starve to death.

Need we give more evidence to  what might happen to the heat sensitive creatures during  global warming?

Cody S. Szuwalski et al, The collapse of eastern Bering Sea snow crab, Science (2023). DOI: 10.1126/science.adf6035

Gordon H. Kruse, Are crabs in hot water?, Science (2023). DOI: 10.1126/science.adk7565

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