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Comment by Dr. Krishna Kumari Challa on August 6, 2022 at 2:59pm

Early-life acquisition of antimicrobial resistance in newborn children from low- and middle-income countries
Every year, almost 7 million potentially serious bacterial infections are estimated to occur in newborns, resulting in more than 550,000 annual neonatal deaths. Most of these infections and deaths happen in LMICs, where often scarce resources can limit the capacity to diagnose and treat sepsis. These problems are further complicated by the global rise of antimicrobial resistance (AMR), particularly the rapid spread of gram-negative bacteria that are resistant to antibiotics—including Klebsiella pneumoniae, Escherichia coli, and Enterobacter cloacae that are no longer susceptible to ß-lactam antibiotics, such as ampicillin and ceftazidime. AMR is already estimated to account for approximately 5 million deaths a year worldwide, and has been predicted to result in 10 million annual deaths by 2050.
Despite neonatal sepsis representing such a major health problem in LMICs, it is still unclear how, when, and where newborn babies acquire life-threatening infections. Furthermore, the factors associated with the presence of AMR in these cases are also still being elucidated. For example, there have been no studies in LMICs examining whether the presence of antibiotic-resistant bacteria in mothers is linked to the development of sepsis in their newborns.

In a new study published in Nature Microbiology, scientists decided to look at the presence of antibiotic resistance genes (ARGs) in the gut microbiota—the collection of microbes that are present in the human gut—of mothers and their babies from 7 LMICs in Africa and South Asia. As part of the "Burden of Antibiotic Resistance in Neonates from Developing Societies" study, or BARNARDS—a network of 12 clinical sites across Bangladesh, Ethiopia, India, Nigeria, Pakistan, Rwanda and South Africa—they recruited 35,040 mothers and 36,285 neonates. From these, they collected 18,148 rectal swabs (15,217 from mothers and 2,931 from neonates, including 626 with sepsis), which were used to grow the bacteria present in these samples and assess the presence of clinically important ARGs in the microbiota of mothers and their babies. The authors found that a large number of samples carried genes linked to antibiotic resistance, suggesting that AMR is far more widespread in these settings than previously anticipated.

For example, samples from around 1 in 5 neonates (18.5%) were positive for blaNDM, a gene that encodes New Delhi metallo-beta-lactamase, which is an enzyme that can destroy ß-lactam antibiotics including the commonly used carbapenems, resulting in the bacteria being resistant against this drug. Importantly, the researchers found that ARGs were present in neonates within hours of birth, indicating that initial colonization of the newborns with antibiotic-resistant bacteria occurred at birth or soon after, likely through contact with the mother or from the hospital environment.

Maria Carvalho, Antibiotic resistance genes in the gut microbiota of mothers and linked neonates with or without sepsis from low- and middle-income countries, Nature Microbiology (2022). DOI: 10.1038/s41564-022-01184-y. www.nature.com/articles/s41564-022-01184-y

Comment by Dr. Krishna Kumari Challa on August 6, 2022 at 2:58pm

Sterile mice produce rat sperm

Researchers generated rat sperm cells inside sterile mice using a technique called blastocyst complementation. The advance appears August 4 in the journal Stem Cell Reports.
This new study shows that scientists can use sterile animals as hosts for the generation of germ cells from other animal species.
Aside from a conceptual advancement, this notion can be utilized to produce endangered animal species gametes inside more prevalent animals. Other implications may involve an improved method to produce rat transgenic models for biomedical research.
Pluripotent stem cells (PSCs) provide a powerful tool for biomedical research, but the generation of gametes in the form of eggs or sperm cells from PSCs is a highly challenging endeavor. In prior studies, researchers used a technique called blastocyst complementation to generate rat organs in mice using PSCs and mutated mouse embryos that cannot produce specific organs. Building on this work, Bar-Nur and his collaborators wondered whether it would be possible to generate rat sperm inside mice that carry a genetic mutation that otherwise renders them sterile.

To test this idea, the researchers injected rat PSCs into mouse embryos to produce mouse-rat chimeras. An essential gene for sperm production was mutated in the mouse blastocysts. The rat stem cells developed together with the mouse cells, thereby generating a chimeric animal composed of genotypes from the two species. As a consequence of the genetic sterility-inducing mutation, an empty niche developed inside the testes, which enabled the rat cells to colonize them and exclusively generate rat sperm in mouse-rat chimeras. The sperm cells could fertilize rat egg cells, but the embryos did not develop normally or give rise to live offspring.

The interesting thing observed in this study was that all the sperm cells inside the chimeras were of rat origin. As such, the mouse host environment, which was sterile due to a genetic mutation, was still able to support efficient sperm cell production from a different animal species.

Although the researchers were able to generate rat sperm cells that morphologically appeared indistinguishable from normal rat sperm cells, these cells were immotile and the fertilization rates of rat eggs was significantly lower in comparison to rat sperm cells produced in rats. Nonetheless, the work provides a proof-of-principle that one can generate sperm cells of one animal species in another by mixing the two species in an artificially generated organism called a chimera. Using sterile mice for genetically modified rat PSCs may speed up the production of transgenic rats to model human diseases in biomedical research.

Ori Bar-Nur, Exclusive generation of rat spermatozoa in sterile mice utilizing blastocyst complementation with pluripotent stem cells, Stem Cell Reports (2022). DOI: 10.1016/j.stemcr.2022.07.005. www.cell.com/stem-cell-reports … 2213-6711(22)00364-2

Comment by Dr. Krishna Kumari Challa on August 6, 2022 at 2:58pm

Researchers achieve world's first international holographic teleportation

Holographic teleportation sounds like something out of Star Wars or Star Trek, but instead of the bridge of a flashy interstellar spaceship, a world-first technological achievement took place in a nondescript boardroom on campus at Western recently.

The term holographic teleportation, or holoport, is a combination of hologram and teleport: when a hologram of a person or object is transmitted instantaneously to another location.

On the afternoon of July 27, a small group of students from the Western Institute for Space Exploration (Western Space) gathered to witness and take part in the world's first international holoport demonstration.

https://www.youtube.com/watch?v=9A5-iUUD1G0&t=59s

Comment by Dr. Krishna Kumari Challa on August 6, 2022 at 2:56pm

How the genome is packed into chromosomes that can be faithfully moved during cell division

Researchers discovered a molecular mechanism that confers special physical properties to chromosomes in dividing human cells to enable their faithful transport to the progeny. They showed how a chemical modification establishes a sharp surface boundary on chromosomes, thus allowing them to resist perforation by microtubules of the spindle apparatus. The findings are published in the journal Nature.

When cells divide, they need to transport exactly one genome copy to each of the two daughter cells. Faithful genome segregation requires the packaging of extremely long chromosomal DNA molecules into discrete bodies so that they can be efficiently moved by the mitotic spindle, a filament system composed of thousands of microtubules. The new findings shed light on how mitotic chromosomes resist the constant pushing and pulling forces generated by the microtubules. Amidst this complex system, the distinct physical properties are conferred to the chromosomes by changing the levels of histone acetylation, a chemical modification within the chromatin fiber.
Prior work had shown that, in dividing cells, the chromatin fibers are folded into loops by a large protein complex called condensin. However, the role of condensin alone could not explain why chromosomes appear as dense bodies with a sharp surface rather than a loose structure resembling a bottlebrush. Some studies had suggested a role of histone acetylation in regulating the level of compaction during cell division, but the interplay of histone acetylation with condensin and its functional relevance remained unclear. This new work is now able to conceptually disentangle the two mechanisms.
The team varied the levels of condensin and histone acetylation to study their precise effects. Removing condensin disrupted the elongated shape of chromosomes in dividing cells and lowered their resistance to pulling forces but did not affect their level of compaction. Combining condensin depletion with a treatment that increases the levels of histone acetylation caused massive chromatin decompaction in dividing cells, and perforation of chromosomes by microtubules.

The researchers hypothesized that chromatin is organized as a swollen gel throughout most of the cell cycle (when it is relatively highly acetylated) and that this gel compacts to an insoluble form during cell division when the acetylation levels globally decrease. They then developed an assay to probe the solubility of chromatin by fragmenting mitotic chromosomes into small pieces. The fragments of mitotic chromosomes formed droplets of liquid chromatin, but when the acetylation level was increased, the chromatin fragments dissolved in the cytoplasm. These observations support a model where a global reduction of chromatin acetylation during mitosis establishes an immiscible chromatin gel with a sharp phase boundary, providing a physical basis for resistance against microtubule perforation.
With further experiments involving pure chromatin that was reconstituted in vitro, and by probing chromatin access by various soluble macromolecules, the team found that immiscible chromatin forms a structure dense in negative charge that excludes negatively charged macromolecules and microtubules. This study shows how DNA looping by the condensin complex cooperates with a chromatin phase separation process to build mitotic chromosomes that resist both pulling and pushing forces exerted by the spindle. The deacetylation of histones during cell division hence confers unique physical properties to chromosomes that are required for their faithful segregation.
Daniel Gerlich, A mitotic chromatin phase transition prevents perforation by microtubules, Nature (2022). DOI: 10.1038/s41586-022-05027-y. www.nature.com/articles/s41586-022-05027-y

Comment by Dr. Krishna Kumari Challa on August 5, 2022 at 7:51am

Scientists reveal how detergents actually work

Scientists have discovered the precise way detergents break biological membranes, which could increase our understanding of how soaps work to kill viruses like COVID-19.

Detergents play a role in everyday life, from removing tough stains and cleaning messy hands to fixing sticky locks. On the nanoscale, they are extremely destructive, and only a few droplets in water can rupture and kill living organisms. This property has led to their widespread use and many soap formulations have been developed to kill disease-carrying viruses, including COVID-19.

Understanding the precise molecular-level mechanisms through which detergents work may help us better design antiviral agents that can combat disease at the earliest possible stage.

For the study, the scientists looked at the detergent Tween-20, which is a key protective ingredient in many products such as handwashes.

Detergent molecules like Tween-20 are shaped like an ice cream cone. At the top of the cone is a region that interacts strongly with water, and at the bottom a group of atoms repel water and form a pointed tail. When you wash your hands with soap, an army of detergent molecules surround the bacteria and viruses on your skin, and in an attempt to escape the surrounding water, they scurry towards and bombard them, tails first, squeezing their membrane envelopes and breaking them apart.

The chemical properties of detergents have been studied in detail, but until now the precise, molecular level details of the interaction have been difficult to assess because of a lack of tools and techniques capable of capturing the entire process.

Researchers  have now developed a series of methods to try and learn more about these important interactions. They  created a series of highly-controllable membrane balls, and they used a molecular nanoruler known as single-molecule FRET ( fluorescence resonance energy transfer), to measure how constituents of the membranes move apart during their interaction with detergents.

They discovered that after Tween-20 binds to the membranes, the balls expand significantly and pores form on their surface before they completely fragment.

To confirm their findings, the researchers used computer simulations to model how the membranes evolved.

The experimental results from different approaches matched up extremely well, and the molecular dynamics simulations allowed scientists to extract otherwise hidden physics governing the process.

Lara Dresser et al, Tween-20 Induces the Structural Remodeling of Single Lipid Vesicles, The Journal of Physical Chemistry Letters (2022). DOI: 10.1021/acs.jpclett.2c00704

Comment by Dr. Krishna Kumari Challa on August 5, 2022 at 7:44am

 Bioscientists use mixed-reality headset, custom software to measure vegetation in the field

https://www.youtube.com/watch?v=dBHfxvhMChU&t=145s

Comment by Dr. Krishna Kumari Challa on August 5, 2022 at 7:44am

Novel Antibiotic kills bacteria via a new two-step mechanism

Scientists at Utrecht University have discovered a new mechanism antibiotics use to kill bacteria. The antibiotic teixobactin uses a dual molecular strategy: it blocks the bacterial cell wall synthesis and destructs the cell membrane, the researchers write in the scientific journal Nature. The new insights will enable the design of powerful antibiotics against which bacteria do not readily develop resistance.

Antibiotics are used to treat bacterial infections and are among the most widely used drugs worldwide. They are vital to combat many infections in the respiratory and intestinal tracts, and various skin conditions. However, bacteria have become increasingly resistant to antibiotics, as most antibiotic classes currently used in clinics have been in use for about half a century. In 2015, scientists  succeeded in isolating teixobactin, the first novel antibiotic discovered in about 40 years.

Teixobactin came from so-called "unculturable" bacteria that do not grow under conventional laboratory conditions and shows extraordinary efficacy against bacterial pathogens without detectable resistance. However, how teixobactin killed bacteria was not understood. Most antibiotics bind to the ribosome, and by doing so, they inhibit the protein production of the bacteria. But there are also antibiotics that hinder bacteria's production of peptidoglycan, a sort of protective envelope that surrounds the bacteria. Teixobactin also does this, it soon appeared, but not in the usual way.

Bacteria need a special lipid called lipid II to build their protective envelope around them. We show at atomic level that teixobactin targets and sequesters lipid II. Afterwards, teixobactin and lipid II together form long fibrils on bacterial cell membranes. Gradually, this creates a kind of valley in the landscape of the cell membrane, which then breaks down and damages the membrane. The  researchers turned out to have found a biomolecular mechanism that was unknown to science until now. "It is a unique killing strategy."

 Markus Weingarth, Teixobactin kills bacteria by a two-pronged attack on the cell envelope, Nature (2022). DOI: 10.1038/s41586-022-05019-y. www.nature.com/articles/s41586-022-05019-y

Comment by Dr. Krishna Kumari Challa on August 5, 2022 at 7:43am

Salt in sea spray found to be the reason for less lightning over tropical oceans

An international team of researchers has uncovered the reason that less lightning occurs over tropical oceans than over land. In their paper published in the journal Nature Communications, the group describes their multi-year study of atmospheric conditions over the oceans bordering Africa and what it showed about salt in sea spray and its impact on lightning.

Scientists and mariners have known for a long time that lightning is less common over the ocean than it is over land—but the reason has not been clear. To find the answer, the researchers obtained atmospheric data for Africa and the oceans around it for the five-year period 2013 to 2017. The data included numbers of lightning flashes, rainfall, temperatures and cloud representations. They looked for differences in atmospheric conditions in storms that occurred over land versus those that occurred over the sea and found one main difference: the amount of salt in the air.

Lightning is produced when upwardly moving air in clouds forms ice crystals—aerosol particles then begin to bump into one another, creating an electrical charge. Lightening happens when the electrical field in one part of the cloud becomes positively charged (usually at the top of the cloud) and another negatively charged (usually at the bottom of the cloud). And clouds form, of course, when moisture evaporates from the surface of the Earth and the water drops bond with aerosols.

The researchers found that things are slightly different over the ocean. When water evaporates from the sea, it bears a load of salt. When the salt water bonds with aerosols to form water droplets, they tend to be bigger and heavier than those that form over land due to the salt—and that results in more of the water in the clouds falling as rain before it can rise up and form ice crystals. The result is far fewer lightning discharges.

Zengxin Pan et al, Coarse sea spray inhibits lightning, Nature Communications (2022). DOI: 10.1038/s41467-022-31714-5

The researchers suggest their findings could be useful in improving the accuracy of both climate models and meteorological reports. It could also conceivably lead some to attempt to seed storm clouds with salt to reduce their severity.

Comment by Dr. Krishna Kumari Challa on August 3, 2022 at 9:47am

Researchers discover one of the largest known bacteria-to-animal gene transfers inside a fruit flyA fruit fly genome is not just made up of fruit fly DNA—at least for one fruit fly species. New research shows that one fruit fly species contains whole genomes of a kind of bacteria, making this finding the largest bacteria-to-animal transfer of genetic material ever discovered. The new research also sheds light on how this happens.
Scientists used new genetic long-read sequencing technology to show how genes from the bacteria Wolbachia incorporated themselves into the fly genome up to 8,000 years ago.The researchers say their findings show that unlike Darwin's finches or Mendel's peas, genetic variation isn't always small, incremental, and predictable.In addition to the long reads, the researchers validated junctions between integrated bacteria genes and the host fruit fly genome. To determine if the bacteria genes were functional and not just DNA fossils, the researchers sequenced the RNA from fruit flies specifically looking for copies of RNA that were created from templates of the inserted bacterial DNA. They showed the bacteria genes were encoded into RNA and were edited and rearranged into newly modified sequences indicating that the genetic material is functional.
An analysis of the unique sequences revealed that the bacteria DNA integrated into the fruit fly genome in the last 8,000 years—exclusively within chromosome 4—expanding the chromosome size by making up about 20 percent of chromosome 4. Whole bacterial genome integration supports a DNA-based rather than an RNA-based mechanism of integration.
They also found nearly a complete second genome and much more with almost 10 copies of some bacterial genome regions.
Wolbachia is an intracellular bacteria that infects numerous types of insects. Wolbachia transmits its genes maternally through female egg cells. Some research has showed that these infections are more mutualistic than parasitic, giving insects advantages, such as resistance to certain viruses.

Eric S. Tvedte et al, Accumulation of endosymbiont genomes in an insect autosome followed by endosymbiont replacement, Current Biology (2022). DOI: 10.1016/j.cub.2022.05.024

Comment by Dr. Krishna Kumari Challa on August 3, 2022 at 9:38am

Scientists reveal how detergents actually work
Scientists have discovered the precise way detergents break biological membranes, which could increase our understanding of how soaps work to kill viruses like COVID-19.
Detergents play a role in everyday life, from removing tough stains and cleaning messy hands to fixing sticky locks. On the nanoscale, they are extremely destructive, and only a few droplets in water can rupture and kill living organisms. This property has led to their widespread use and many soap formulations have been developed to kill disease-carrying viruses, including COVID-19.
Understanding the precise molecular-level mechanisms through which detergents work may help us better design antiviral agents that can combat disease at the earliest possible stage.
For the study, the scientists looked at the detergent Tween-20, which is a key protective ingredient in many products such as handwashes.Detergent molecules like Tween-20 are shaped like an ice cream cone. At the top of the cone is a region that interacts strongly with water, and at the bottom a group of atoms repel water and form a pointed tail. When you wash your hands with soap, an army of detergent molecules surround the bacteria and viruses on your skin, and in an attempt to escape the surrounding water, they scurry towards and bombard them, tails first, squeezing their membrane envelopes and breaking them apart.The chemical properties of detergents have been studied in detail, but until now the precise, molecular level details of the interaction have been difficult to assess because of a lack of tools and techniques capable of capturing the entire process.Researchers  have now developed a series of methods to try and learn more about these important interactions. They  created a series of highly-controllable membrane balls, and they used a molecular nanoruler known as single-molecule FRET (fluorescence resonance energy transfer), to measure how constituents of the membranes move apart during their interaction with detergents.They discovered that after Tween-20 binds to the membranes, the balls expand significantly and pores form on their surface before they completely fragment.To confirm their findings, the researchers used computer simulations to model how the membranes evolved.The experimental results from different approaches matched up extremely well, and the molecular dynamics simulations allowed scientists to extract otherwise hidden physics governing the process.
Lara Dresser et al, Tween-20 Induces the Structural Remodeling of Single Lipid Vesicles, The Journal of Physical Chemistry Letters (2022). DOI: 10.1021/acs.jpclett.2c00704

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