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Comment by Dr. Krishna Kumari Challa on April 6, 2023 at 12:42pm

Study finds evidence of no common blood microbes in healthy humans

There is no stable microbial community residing in the bloodstream of healthy humans, according to a new study.

The new Nature Microbiology paper makes an important confirmation as blood donations are a crucial part of medical practice. Understanding what types of microbes may be found in blood may allow the development of better microbial tests in blood donations, which would minimize the risk of transfusion-related infections.

Human blood is generally considered sterile. While sometimes microorganisms will enter the bloodstream such as via a wound or after tooth-brushing, mostly this is quickly resolved by the immune system.

But in recent decades this paradigm has been challenged by speculation that the blood could host a community of microbes. This new study has confirmed this is not the case, as most people's blood does not contain microbes, and the microbial species found in some people's blood varied substantially between individuals.

In these investigations, after accounting for contamination that is rife in microbiome investigations, the team found that microbes were only rarely and sporadically detected in blood, instead of existing as stable communities. Among their sample of 9,770 people, 84% of people did not have any microbes in their blood sample, and less than 5% of people shared the same species.

The scientists also found evidence that some bacteria in the blood of healthy individuals might be replicating and most of these bacteria are typically found in the human gut, oral, or skin microbiomes. Their findings suggest that microbes do occasionally enter the bloodstream from other body sites without causing disease, but there is no core set of species colonizing the blood of healthy individuals.

The findings also provide a useful resource for the types of microbes that one might expect to occasionally see in the blood of healthy humans. Characterizing the range of microbial species present in the blood of healthy individuals forms a crucial baseline for comparison with that of diseased individuals, shedding light on how blood microbial profiles may correlate with health status.

Cedric C. S. Tan et al, No evidence for a common blood microbiome based on a population study of 9,770 healthy humans, Nature Microbiology (2023). DOI: 10.1038/s41564-023-01350-w

No microbial community in the blood of healthy individuals, Nature Microbiology (2023). DOI: 10.1038/s41564-023-01364-4

Comment by Dr. Krishna Kumari Challa on April 6, 2023 at 12:31pm

Meanwhile, the abundance of the amino acid glycine was found to be lower in A0022 compared to C0008, while the abundance of β-Alanine showed the opposite trend. Accordingly, the ratio of β-Alanine to glycine was higher for A0022 than for C0008. This ratio was shown previously to be indicative of the extent of aqueous alteration operating on planetesimals. Accordingly, it was hypothesized that some reaction related to higher levels of aqueous alteration in A0022 may explain the high abundance of DMG in this particle, compared to C0008.

As such, the mineral phases were examined to see if any additional evidence for what reaction may be causing the different amino acids abundances between the Ryugu particles. It was found that the abundance of secondary minerals (formed after aqueous alteration), including carbonate, magnetite and Fe-sulfides, was higher in A0022 than in C0008.

In particular, the high abundance of carbonate pointed towards a larger quantity of CO or CO₂ within the region of the planetesimal where A0022 had been altered, compared to C0008. In conjunction with the evidence for more intense aqueous alteration from the β-Alanine to glycine ratio, this indicated that more ice in general may have been present in the precursor of A0022 than in C0008.

One way to commercially produce DMG, an important nutrient for humans, is the through the Eschweiler–Clarke reaction. This reaction requires the interaction of glycine with formic acid and formaldehyde in water and also produces CO₂. Glycine, formaldehyde and formic acid are all found in comets and so it is expected that they would be present in the planetesimal precursors of asteroids.

Therefore, if the Eschweiler–Clarke reaction occurred during aqueous alteration within the precursor of A0022, then it could explain the high level of DMG and lower abundance of glycine in this particle, compared to C0008. Additionally, the CO₂ produced could have further contributed to the formation of carbonates in A0022.

Overall, the findings of the study indicate that slight differences in the conditions present during aqueous alteration on planetesimals can have big effects on the end abundances of amino acids. Some amino acids can be destroyed and others created and this in turn will affect the availability of amino acids at the origin of life on Earth.

Christian Potiszil et al, Insights into the formation and evolution of extraterrestrial amino acids from the asteroid Ryugu, Nature Communications (2023). DOI: 10.1038/s41467-023-37107-6

Part 3

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Comment by Dr. Krishna Kumari Challa on April 6, 2023 at 12:29pm

Amino acids are within all living things on Earth, being the building blocks of proteins. Proteins are essential for many processes within living organisms, including catalyzing reactions (enzymes), replicating genetic material (ribosomes), transporting molecules (transport proteins) and providing a structure to cells and organisms (e.g. collagen).

Therefore, amino acids would have been needed in significant amounts within the region where life began on Earth.

Previous work has identified a number of possible settings both on the Early Earth and in extraterrestrial environments that can form amino acids. Interestingly, most amino acids come in at least two forms, whose structures represent mirror images of each other, similar to human hands. Accordingly, these are often referred to as the right-handed or left-handed optical isomers. One interesting characteristic of life on Earth is that it uses one particular type of amino acids in its proteins, the left-handed optical isomer.

Currently, only a certain class of meteorites (carbonaceous chondrites) are known to contain excesses of left-handed optical isomers, which has led to the idea that the amino acids used by life may have originated from these meteorites. Despite this, the amino acids in meteorites could have formed before their incorporation into the meteorites or after the meteorites had already formed.

In a study now published in Nature Communications, a team of scientists analyzed several fragments of the asteroid Ryugu and calculated the abundance of amino acids within them. The abundance of the mineral phases within the particles had been previously reported in another publication, which allowed for a comparison between the abundance of amino acids and minerals. It was found that one particle (A0022) contained a high abundance of an amino  acid that is uncommon in extraterrestrial materials, called dimethylglycine (DMG), whereas the other particle (C0008) did not contain this amino acid above detection limit.

Part 2

Comment by Dr. Krishna Kumari Challa on April 6, 2023 at 12:27pm

How were amino acids, one of the key building blocks of life, formed before the origin of life on Earth?

Our solar system formed from a molecular cloud, which was composed of gas and dust that was emitted into the interstellar medium (ISM), a vast space between stars. On collapse of the molecular cloud, the early sun was formed, with a large disk of gas and dust orbiting it. The dusty material collided to produce rocky material that would eventually grow in size to become large bodies called planetesimals.

The planetesimals that formed far enough from the sun, also contained large quantities of ice. The ice consisted of water and other volatile compounds, such as carbon monoxide (CO), carbon dioxide (CO2), methanol (CH3OH) and ammonia (NH3), as well as many other organic compounds, likely including some amino acids. Eventually, the ice melted due to the presence of radioactive material that heated up the bodies. This period of liquid water (termed aqueous alteration) enabled many reactions to occur, including Strecker synthesis and Formose-like reactions, the result being the production of new organic material, including amino acids.

The same process also changed the rocky materials from their original minerals to new secondary minerals, such as phyllosilicates, carbonates, Fe-oxides and Fe-sulfides.

After several millions of years, the planetesimals began to freeze, as the radioactive material was used up. Later catastrophic collisions and interaction with the solar systems planets broke up the large bodies and sent their asteroidal and cometary fragments close to Earth.

Further impact events have since delivered fragments of these asteroids and comets to the Earth's surface, supplying the Earth with large quantities of organic material, including amino acids, over the course of its history.

Part 1

Comment by Dr. Krishna Kumari Challa on April 6, 2023 at 12:03pm

Previously unknown isotope of uranium discovered

A team of nuclear physicists affiliated with multiple institutions in Japan, working with a colleague from Korea, has discovered a previously unknown uranium isotope with atomic number 92 and mass 241. In their study, reported in the journal Physical Review Letters, the group forced the isotope to reveal itself and tested the results of their efforts to show that what they had found was indeed uranium-241.

T. Niwase et al, Discovery of New Isotope U241 and Systematic High-Precision Atomic Mass Measurements of Neutron-Rich Pa-Pu Nuclei Produced via Multinucleon Transfer Reactions, Physical Review Letters (2023). DOI: 10.1103/PhysRevLett.130.132502

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Study shows soil pollution in urban green spaces and natural areas ...

An international study shows that soil in urban green spaces and natural areas share similar levels of multiple contaminants such as metals, pesticides, microplastics and antibiotic resistance genes around the world. Soil contamination is one of the main threats to the health and sustainability of ecosystems.

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Scientists invent spray cooling to lower carbon footprint of data c...

Scientists from Nanyang Technological University, Singapore (NTU Singapore) have invented a more sustainable and green method for cooling down servers in data centers, potentially reducing up to 26% in both energy costs and carbon footprint.

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Euchromatin is not really open in living cells, shows study

DNA and associated proteins in active regions of the genome are condensed but behave like a viscous liquid at the molecular level. This finding greatly increases our understanding of the physical nature of expressed genome 

Comment by Dr. Krishna Kumari Challa on April 6, 2023 at 8:53am

The researchers realized that the darkest lunar eclipses all occurred within a year or so of major volcanic eruptions. Since they know the exact days of the eclipses, it opened the possibility of using the sightings to narrow down when the eruptions must have happened.

The researchers found that scribes in Japan took equal note of lunar eclipses. One of the best known, Fujiwara no Teika, wrote of an unprecedented dark eclipse observed on 2 December 1229: "The old folk had never seen it like this time, with the location of the disk of the Moon not visible, just as if it had disappeared during the eclipse... It was truly something to fear." The stratospheric dust from large volcanic eruptions was not only responsible for the vanishing moon. It also cooled summer temperatures by limiting the sunlight reaching the Earth's surface. This in turn could bring ruin to agricultural crops.

Strong tropical eruptions can induce global cooling on the order of roughly 1°C over a few years. They can also lead to rainfall anomalies with droughts in one place and floods in another.

Despite these effects, people at the time could not have imagined that the poor harvests or the unusual lunar eclipses had anything to do with volcanoes—the eruptions themselves were all but one undocumented. Scientists only knew about these eruptions because they left traces in the ice of Antarctica and Greenland. By putting together the information from ice cores and the descriptions from medieval texts they can now make better estimates of when and where some of the biggest eruptions of this period occurred.

The collective effect of the medieval eruptions on Earth's climate may have led to the Little Ice Age, when winter ice fairs were held on the frozen rivers of Europe.

Sébastien Guillet, Lunar eclipses illuminate timing and climate impact of medieval volcanism, Nature (2023). DOI: 10.1038/s41586-023-05751-z. www.nature.com/articles/s41586-023-05751-z

Part 2

Comment by Dr. Krishna Kumari Challa on April 6, 2023 at 8:47am

The unexpected contribution of medieval monks to volcanology

By observing the night sky, medieval monks unwittingly recorded some of history's largest volcanic eruptions. An international team of researchers drew on readings of 12th and 13th century European and Middle Eastern chronicles, along with ice core and tree ring data, to accurately date some of the biggest volcanic eruptions the world has ever seen.

Their results, reported in the journal Nature, uncover new information about one of the most volcanically active periods in Earth's history, which some think helped to trigger the Little Ice Age, a long interval of cooling that saw the advance of European glaciers.

It took the researchers almost five years to examine hundreds of annals and chronicles from across Europe and the Middle East, in search of references to total lunar eclipses and their coloration. Total lunar eclipses occur when the moon passes into the Earth's shadow. Typically, the moon remains visible as a reddish orb because it is still bathed in sunlight bent round the Earth by its atmosphere. But after a very large volcanic eruption, there can be so much dust in the stratosphere—the middle part of the atmosphere starting roughly where commercial aircraft fly—that the eclipsed moon almost disappears.

Medieval chroniclers recorded and described all kinds of historical events, including the deeds of kings and popes, important battles, and natural disasters and famines. Just as noteworthy were the celestial phenomena that might foretell such calamities. Mindful of the Book of Revelation, a vision of the end times that speaks of a blood-red moon, the monks were especially careful to take note of the moon's coloration. Of the 64 total lunar eclipses that occurred in Europe between 1100 and 1300, the chroniclers had faithfully documented 51. In five of these cases, they also reported that the moon was exceptionally dark.

Part 1

Comment by Dr. Krishna Kumari Challa on April 5, 2023 at 1:10pm

When you’re having a cast removed, why doesn’t the machine cut your limb?

An orthopaedic cast is usually removed with a special cast saw, which is an oscillating power tool. While it might look like it could cause a lot of damage, a cast saw is designed with a sharp, small-toothed blade that rapidly oscillates back and forth over a very small angle to cut material.

This is quite different to a normal circular saw, which has a rotating blade. A cast saw needs resistance to cut, and is specially designed to slice through rigid materials such as plaster. If it comes into contact with soft tissues such as skin, there is less resistance and so the saw will not cause injury.

Comment by Dr. Krishna Kumari Challa on April 5, 2023 at 12:05pm

New shape-shifting antibiotics could fight deadly infections

Antibiotics are essential and effective, but in recent years overuse has led to some bacteria developing resistance to them. The infections are so difficult to treat, the World Health Organization deemed antibiotic resistance a top 10 global public health threat.

Researchers have now  created a new weapon against these drug-resistant superbugs—an antibiotic that can shape-shift by rearranging its atoms.

They came up with the idea of shape-shifting antibiotics while observing tanks in military training exercises. With rotating turrets and nimble movements, the tanks could respond quickly to possible threats.

A few years later, the researchers learned of a molecule called bullvalene. Bullvalene is a fluxional molecule, meaning its atoms can swap positions. This gives it a changing shape with over a million possible configurations—exactly the fluidity they were  looking for.

Several bacteria, including MRSA, VRSA, and VRE, have developed resistance to a potent antibiotic called vancomycin, used to treat everything from skin infections to meningitis. Moses thought he could improve the drug's bacteria-fighting performance by combining it with bullvalene.

Then they turned to click chemistry, a Nobel Prize–winning class of fast, high-yielding chemical reactions that "click" molecules together reliably. This makes the reactions more efficient for wide-scale use.

Using this technique, teh researchers created a new antibiotic with two vancomycin "warheads" and a fluctuating bullvalene center.

They tested the new drug in collaboration with Dr. Tatiana Soares da-Costa (University of Adelaide). The researchers gave the drug to VRE-infected wax moth larvae, which are commonly used to test antibiotics. They found the shape-shifting antibiotic significantly more effective than vancomycin at clearing the deadly infection. Additionally, the bacteria didn't develop resistance to the new antibiotic.

Researchers can use click chemistry with shape-shifting antibiotics to create a multitude of new drugs to use against various microbes.

Alessandra Ottonello et al, Shapeshifting bullvalene-linked vancomycin dimers as effective antibiotics against multidrug-resistant gram-positive bacteria, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2208737120

Comment by Dr. Krishna Kumari Challa on April 5, 2023 at 11:38am

The experiments carried out by this team of researchers yielded very interesting results. Notably, they showed that serotonin can suppress calcium signals in retinal axons and the release of glutamate in the thalamus. This ultimately reduces the transmission of visual signals from the eye to the thalamus.

When they analyzed their results more in detail, the researchers  found that some classes of retinal axons tended to be more suppressed by serotonin, with classes that responded to broad changes in light levels being more affected than those responding to fine visual details.

The researchers also compared the selective modulation observed in their experiments to that naturally occurring when animals or humans are highly aroused. They found that periods of high arousals that were not accompanied by an increase in the release of serotonin tended to suppress the retinal axons transmitting information about fine details, rather than changes in light levels.

Overall, the results of this study confirm that different internal states can impact the processing of separate types of visual information. 

Jasmine D.S. Reggiani et al, Brainstem serotonin neurons selectively gate retinal information flow to thalamus, Neuron (2022). DOI: 10.1016/j.neuron.2022.12.006

Part 2

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