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Comment by Dr. Krishna Kumari Challa on September 9, 2022 at 9:45am

Two new trials find no link between vitamin D supplements and reduced risk of COVID-19

Two large clinical trials published by The BMJ today show that boosting vitamin D levels in adults during the SARS-CoV-2 pandemic was not associated with protection against respiratory tract infections or COVID-19.

Vitamin D metabolites have long been recognized to support innate immune responses to respiratory viruses and bacteria, and some studies have shown that vitamin D may protect against respiratory tract infections, particularly among those who are vitamin D-deficient.

Vitamin D has therefore received much attention for its potential role in preventing and treating COVID-19, but most studies published so far are observational and have shown mixed results.

The first trial was carried out in the UK between December 2020 and June 2021 and involved 6,200 adults (16 years and over) not using vitamin D supplements at enrollment.

Half (3,100 participants) were offered a vitamin D blood test and those found to have low vitamin D levels (2,674; 86%) received either 3200 IU/day or 800 IU/day of vitamin D supplements for six months, while the other half (controls) received no test or supplements.

Neither of the vitamin D doses showed any effect on diagnosed acute respiratory tract infections or lateral flow test or RT-PCR-confirmed COVID-19 cases over a six-month follow-up period. The number of adverse events was similar between groups, and no serious adverse event was attributed to study supplements.

The second trial was conducted in Norway between November 2020 and June 2021 using cod liver oil, which contains low doses of vitamin D and vitamin A as well as omega-3 fatty acids.

A total of 34,741 adults (18-75 years) who were not using vitamin D supplements received either 5 mL cod liver oil or 5 mL placebo (corn oil) daily for six months. The majority of participants (86%) who were tested had adequate vitamin D levels at the start of the study.

Again, the researchers found no effect of cod liver oil on acute respiratory infections or PCR-confirmed COVID-19, compared with placebo. The cod liver oil group had no more side effects than the placebo group and only low-grade side effects were reported.

Effect of a test-and-treat approach to vitamin D supplementation on risk of all cause acute respiratory tract infection and covid-19: phase 3 randomised controlled trial (CORONAVIT), The BMJ (2022). DOI: 10.1136/bmj-2022-071230

Comment by Dr. Krishna Kumari Challa on September 9, 2022 at 9:42am

Intelligent microscopes for detecting rare biological events

Now researchers need not wait for hours together to image bacterial cells division

Biophysicists have now found a way to automate microscope control for imaging biological events in detail while limiting stress on the sample, all with the help of artificial neural networks. Their technique works for bacterial cell division, and for mitochondrial division. The details of their intelligent microscope are described in Nature Methods.

Suliana Manley, Event-driven acquisition for content-enriched microscopy, Nature Methods (2022). DOI: 10.1038/s41592-022-01589-x. www.nature.com/articles/s41592-022-01589-x

Comment by Dr. Krishna Kumari Challa on September 9, 2022 at 9:35am

Modern humans generate more brain neurons than Neandertals

What makes modern humans unique has long been a driving force for researchers. Comparisons with our closest relatives, the Neandertals, therefore provide fascinating insights. The increase in brain size, and in neuron production during brain development, are considered to be major factors for the increased cognitive abilities that occurred during human evolution. However, while both Neandertals and modern humans develop brains of similar size, very little is known about whether modern human and Neandertal brains may have differed in terms of their neuron production during development.

Researchers now show that the modern human variant of the protein TKTL1, which differs by only a single amino acid from the Neandertal variant, increases one type of brain progenitor cells, called basal radial glia, in the modern human brain. Basal radial glial cells generate the majority of the neurons in the developing neocortex, a part of the brain that is crucial for many cognitive abilities. As TKTL1 activity is particularly high in the frontal lobe of the fetal human brain, the researchers conclude that this single human-specific amino acid substitution in TKTL1 underlies a greater neuron production in the developing frontal lobe of the neocortex in modern humans than Neandertals.

Only a small number of proteins have differences in the sequence of their amino acids—the building blocks of proteins—between modern humans and our extinct relatives, the Neandertals and Denisovans. The biological significance of these differences for the development of the modern human brain is largely unknown. In fact, both, modern humans and Neandertals, feature a brain, and notably a neocortex, of similar size, but whether this similar neocortex size implies a similar number of neurons remains unclear.

The researchers focus on one of these proteins that presents a single amino acid change in essentially all modern humans compared to Neandertals, the protein transketolase-like 1 (TKTL1). Specifically, in modern humans TKTL1 contains an arginine at the sequence position in question, whereas in Neandertal TKTL1 it is the related amino acid lysine. In the fetal human neocortex, TKTL1 is found in neocortical progenitor cells, the cells from which all cortical neurons derive. Notably, the level of TKTL1 is highest in the progenitor cells of the frontal lobe.

Researchers observed that basal radial glial cells, the type of neocortical progenitors thought to be the driving force for a bigger brain, increased with the modern human variant of TKTL1 but not with the Neandertal variant. As a consequence, the brains of mouse embryos with the modern human TKTL1 contained more neurons.

They found that with the Neandertal-type of amino acid in TKTL1, fewer basal radial glial cells were produced than with the modern human-type and, as a consequence, also fewer neurons. This shows us that even though we do not know how many neurons the Neandertal brain had, we can assume that modern humans have more neurons in the frontal lobe of the brain, where TKTL1 activity is highest, than Neandertals.

Anneline Pinson et al, Human TKTL1 implies greater neurogenesis in frontal neocortex of modern humans than Neandertals, Science (2022). DOI: 10.1126/science.abl6422. www.science.org/doi/10.1126/science.abl6422

Comment by Dr. Krishna Kumari Challa on September 9, 2022 at 9:10am

Physicists invent intelligent quantum sensor of light waves

Physicists have demonstrated an atomically thin, intelligent quantum sensor that can simultaneously detect all the fundamental properties of an incoming light wave.

The research, published April 13 in the journal Nature, demonstrates a new concept based on quantum geometry that could find use in health care, deep-space exploration and remote-sensing applications.

Typically, when you want to characterize a wave of light, you have to use different instruments to gather information, such as the intensity, wavelength and polarization state of the light. Those instruments are bulky and can occupy a significant area on an optical table. Now we have a single device—just a tiny and thin chip—that can determine all these properties simultaneously in a very short time.

The device exploits the unique physical properties of a novel family of two-dimensional materials called moiré metamaterials. The 2D materials have periodic structures and are atomically thin. If two layers of such a material are overlaid with a small rotational twist, a moiré pattern with an emergent, orders-of-magnitude larger periodicity can form. The resulting moiré metamaterial yields electronic properties that differ significantly from those exhibited by a single layer alone or by two naturally aligned layers.

The sensing device that physicists now chose to demonstrate their new idea incorporates two layers of relatively twisted, naturally occurring bilayer graphene, for a total of four atomic layers.

Chun Ning Lau et al, Reproducibility in the fabrication and physics of moiré materials, Nature (2022). DOI: 10.1038/s41586-021-04173-z

Comment by Dr. Krishna Kumari Challa on September 8, 2022 at 10:33am

Light accelerates conductivity in nature's 'electric grid'

The natural world possesses its own intrinsic electrical grid composed of a global web of tiny bacteria-generated nanowires in the soil and oceans that "breathe" by exhaling excess electrons.

In a new study, researchers discovered that light is a surprising ally in fostering this electronic activity within biofilm bacteria. Exposing bacteria-produced nanowires to light, they found, yielded an up to a 100-fold increase in electrical conductivity.

The dramatic current increases in nanowires exposed to light show a stable and robust photocurrent that persists for hours.

The results could provide new insights as scientists pursue ways to exploit this hidden electrical current for a variety of purposes, from eliminating biohazard waste and creating new renewable fuel sources.

Almost all living things breathe oxygen to get rid of excess electrons when converting nutrients into energy. Without access to oxygen, however, soil bacteria living deep under oceans or buried underground over billions of years have developed a way to respire by "breathing minerals," like snorkeling, through tiny protein filaments called nanowires.

When bacteria were exposed to light, the increase in electrical current surprised researchers because most of the bacteria tested exist deep in the soil, far from the reach of light. Previous studies had shown that when exposed to light nanowire-producing bacteria grew faster.

In the new study researchers concluded that a metal-containing protein known as cytochrome OmcS—which makes up bacterial nanowires—acts as a natural photoconductor: the nanowires greatly facilitate electron transfer when biofilms are exposed to light.

It is a completely different form of photosynthesis. Here, light is accelerating breathing by bacteria due to rapid electron transfer between nanowires.

Researchers are exploring how this insight into bacterial electrical conductivity could be used to spur growth in optoelectronics—a subfield of photonics that studies devices and systems that find and control light—and capture methane, a greenhouse gas known to be a significant contributor to global climate change.

Neu, J., Shipps, C.C., Guberman-Pfeffer, M.J. et al. Microbial biofilms as living photoconductors due to ultrafast electron transfer in cytochrome OmcS nanowires. Nat Commun, 2022 DOI: 10.1038/s41467-022-32659-5

Comment by Dr. Krishna Kumari Challa on September 7, 2022 at 11:44am

Physicists discover new rule for orbital formation in chemical reactions

Squeaky, cloudy or spherical—electron orbitals show where and how electrons move around atomic nuclei and molecules. In modern chemistry and physics, they have proven to be a useful model for quantum mechanical description and prediction of chemical reactions. Only if the orbitals match in space and energy can they be combined—this is what happens when two substances react with each other chemically. In addition, there is another condition that must be met, as researchers  have now discovered: The course of chemical reactions also appears to be dependent on the orbital distribution in momentum space. The results were published in the journal Nature Communications.

 Xiaosheng Yang et al, Momentum-selective orbital hybridisation, Nature Communications (2022). DOI: 10.1038/s41467-022-32643-z

Comment by Dr. Krishna Kumari Challa on September 7, 2022 at 11:04am

How tardigrades survive dehydration

Some species of tardigrades, or water bears as the tiny aquatic creatures are also known, can survive in different environments often hostile or even fatal to most forms of life. For the first time, researchers describe a new mechanism that explains how some tardigrades can endure extreme dehydration without dying. They explored proteins that form a gel during cellular dehydration. This gel stiffens to support and protect the cells from mechanical stress that would otherwise kill them. These proteins have also been shown to work in insect cells and even show limited functionality in human cultured cells.

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Next generation of hearing aids could read lips through masks

A new system capable of reading lips with remarkable accuracy even when speakers are wearing face masks could help create a new generation of hearing aids.

Comment by Dr. Krishna Kumari Challa on September 7, 2022 at 11:00am

Researchers discover toxin that kills bacteria in unprecedented ways

Researchers  have discovered a previously unknown bacteria-killing toxin that could pave the way for a new generation of antibiotics.

The study shows that the bacterial pathogen Pseudomonas aeruginosa, known to cause hospital-acquired infections such as pneumonia, secretes a toxin that has evolved to kill other  species of bacteria.

The key aspect of his discovery is not just that this toxin kills bacteria, but how it does so.This research is significant, because it shows that the toxin targets essential RNA molecules of other bacteria, effectively rendering them non-functional. It's a total assault on the cell because of how many essential pathways depend on functional RNAs. This toxin enters its target, hijacks an essential molecule needed for life, and then uses that molecule to disrupt normal processes.

Researchers say that this development holds great potential for future research that could eventually lead to new innovations that combat infection-causing bacteria.

They think the newly-discovered vulnerability can be exploited for future antibiotic development.

An ADP-ribosyltransferase toxin kills bacterial cells by modifying structured non-coding RNAs, Molecular Cell (2022).

Comment by Dr. Krishna Kumari Challa on September 7, 2022 at 10:47am

Webb Captures A Cosmic Tarantula

Watch this special Space Sparks episode to learn more about the stellar nursery called 30 Doradus, as captured by the NASA/ESA/CSA James Webb Space Telescope.

Comment by Dr. Krishna Kumari Challa on September 7, 2022 at 9:02am

Researchers capture live footage of virus infecting cell

In a first, scientists have captured on video all the steps a virus follows as it enters and infects a living cell in real time and in three dimensions.

Scientists achieved the feat by using advanced imaging called lattice light sheet microscopy as well as chemical and genetic manipulation.

The first part of the video shown here follows a virus engineered to sprout SARS-CoV-2 spike proteins (labeled pink) as it is captured at a cell surface and engulfed by a cellular compartment called an endosome. The virus then fuses with the endosome membrane and injects its genetic material (labeled blue) inside the cell—the steps necessary to kick off a cycle of viral infection and replication.

The second part of the video shows many such viruses inside the cell. The video covers 4 minutes of activity, with snapshots taken every 4 seconds.

The findings, published Sept. 1 in PNAS, provide new insights into the fundamental mechanics of viral infection and could point the way to new methods for intervening before the onset of COVID-19.

The researchers' work reveals that viruses can't fuse with the membrane and release their genomes unless they're bathed in a slightly acidic environment. Experiments indicated that the pH must fall between 6.2 and 6.8, just shy of neutral and on par with bodily fluids such as saliva and urine. Endosomes have such acidity, and the team's measurements confirmed that this is also the pH range inside a typical human nose, where SARS-CoV-2 infection often begins.

https://hms.harvard.edu/news/breaking-entering

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