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Comment by Dr. Krishna Kumari Challa on November 11, 2023 at 9:53am

World's First Entire Eye Transplant

A team of surgeons in New York has performed the world's first transplant of an entire eye in a procedure widely hailed as a medical breakthrough, although it isn't yet known whether the man will ever see through the donated eye. The groundbreaking surgery involved removing part of the face and the whole left eye – including its blood supply and optic nerve – of a donor and grafting them onto a lineworker from Arkansas who survived a 7,200-volt electric shock in June 2021.

Aaron James, 46, suffered extensive injuries including the loss of his left eye, his dominant left arm above the elbow, his nose and lips, front teeth, left cheek area and chin.
He was referred to NYU Langone Health, a leading medical center for facial transplants, which carried out the procedure on May 27.

Transplanting an entire eye has long been a holy grail of medical science, and though researchers have had some success in animals – where they have restored partial vision – it's never before been performed in a living person.
The transplanted left eye appears very healthy, said retinal ophthalmologist.
It has a good blood supply, is maintaining its pressure, and is generating an electrical signal, though James is not yet able to see. But the doctors have a lot of hope.
The doctors used bone marrow-derived adult stem cells to promote nerve repair.
Source: News Agencies

Comment by Dr. Krishna Kumari Challa on November 11, 2023 at 9:29am

Why do massive stars make up such a high proportion of runaway stars? There are two competing theories that attempt to explain runaway stars, and both involve massive stars. One is the dynamical ejection scenario (DES), and the other is the binary supernova scenario (BSS).

OB stars often form in binary pairs. In the BSS, one star explodes as a supernova, and the explosion kicks the other star. If the situation is right, the surviving star is given enough energy in the right direction that it can escape from its bond with its partner, which is now a neutron star or a black hole. It can also escape the gravitational pull of the Milky Way. If that happens, it begins its long journey into intergalactic space.

In the DES, there's no dramatic supernova explosion. Instead, a star in a compact, densely packed region experiences gravitational interactions with other stars. Encounters between binary and single stars can produce runaways, and so can encounters between two binary pairs. The OB associations where O-type and B-type stars tend to form are the types of dense environments that can trigger runaway stars. Since most of these stars are massive, most of the runaway stars are, too.

Scientists have been wondering about the two scenarios and debating them for decades. Both scenarios can produce stars with enough velocity to escape the galaxy. In studying their sample of 175 runaway stars, the researchers found that their data favors one explanation over the other.

The higher percentages and higher velocities found for O-type compared to Be-type runaways underline that the dynamical ejection scenario is more likely than the binary supernova scenario.

The percentages of spectral types represented in runaway stars help explain their conclusion. 25% of the O-type stars in their sample are runaways versus 5% of the Be-type. Other studies have come up with different numbers, but as the researchers point out, there is agreement in the sense that the percentage of runaway O stars is significantly higher than for B or Be stars.

Previous research shows that O-type runaway stars have higher velocities than B and Be-type stars. Previous research also shows that dynamical ejection often results in faster, more massive runaways than the binary supernova scenario. 

M. Carretero-Castrillo et al, Galactic runaway O and Be stars found using Gaia DR3, Astronomy & Astrophysics (2023). DOI: 10.1051/0004-6361/202346613. On arXiv: DOI: 10.48550/arxiv.2311.01827

Part 2

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Comment by Dr. Krishna Kumari Challa on November 11, 2023 at 9:26am

Astronomers find dozens of massive stars fleeing the Milky Way

The Milky Way can't hold onto all of its stars. Some of them get ejected into intergalactic space and spend their lives on an uncertain journey. A team of astronomers took a closer look at the most massive of these runaway stars to see what they could find out how they get ejected.

When astronomers observe a field of stars in the Milky Way, one of the things they measure is the velocity distribution. The overall velocity distribution of the stellar population reflects the rotation of the galaxy. And when a star isn't harmonized with the galaxy's rotation, it catches astronomers' attention.

A team of astronomers working with two catalogues of massive stars found a whole bunch of stars moving differently than the galaxy. They're runaway stars that are on their way out of the galaxy.

Nobody knows how many runaway stars are on their way out of our galaxy, but astronomers keep finding more of them. Some estimates say there are 10 million runaway stars fleeing the Milky Way, but we don't know for sure. It may depend on the mechanism that drives them away, and that's something astrophysicists don't fully understand. A new study aims to shed some light on the runaway star phenomenon by looking specifically at massive stars.

A relevant fraction of massive stars are runaway stars. These stars move with a significant peculiar velocity with respect to their environment.

Massive early-type OB stars are the most luminous stars in the Milky Way. OB stars are not only massive and young, they're extremely hot. They form in loosely organized groups with one another called OB associations. Because they're young and hot, they don't last long. They're important in astronomy because they're so massive and energetic and because many of them explode as supernovae. That's why there are specific catalogues dedicated to them.

Part 1

Comment by Dr. Krishna Kumari Challa on November 11, 2023 at 9:19am

Earth's Moon: Why One Side Always Faces Us

Comment by Dr. Krishna Kumari Challa on November 11, 2023 at 9:05am

Even more exciting is how closely the new study's results in mice appear to be reflected in human cells.

With a blood test, doctors can identify people who are at high-risk of developing type 1 diabetes months in advance of the death of their beta cells.

That may be a perfect timeframe for a treatment based on pharmacological inhibition of Atf6 or induction of LIF and other secreted proteins. If we can get there in time to protect these cells with transient senescence, the onset of diabetes might be prevented.

Hugo Lee et al, Stress-induced β cell early senescence confers protection against type 1 diabetes, Cell Metabolism (2023). DOI: 10.1016/j.cmet.2023.10.014

Part 2

Comment by Dr. Krishna Kumari Challa on November 11, 2023 at 9:03am

Relieving stress in insulin-producing cells protects against type 1 diabetes

Removing a gene that manages stress within insulin-producing beta cells draws helpful attention from the immune system, protecting mice predisposed to type 1 diabetes from developing the disease, a new  study shows.

The study also found that changes discovered in the modified mouse beta cells are also present in human beta cells that manage to survive the widespread beta-cell death that characterizes type 1 diabetes.

This gives the researchers hope that their findings, published in the journal Cell Metabolism, may point to a potential new treatment that could be administered very early in the development of diabetes. 

When we eat, our beta cells produce about 1 million molecules of insulin every minute to help maintain normal blood glucose levels. That is a big and stressful job, especially for a part of these beta cells called the endoplasmic reticulum.

The endoplasmic reticulum is like the cell's warehouse staff. It folds the insulin protein molecules that a beta cell produces, packing them for shipping to other parts of the body. If something goes wrong with the protein folding process, the shipping process backs up or even stops, stressing the endoplasmic reticulum. A stress-response gene called Atf6 perks up when a cell is struggling with unfolded proteins. But if Atf6 can't resolve the protein-folding problem, prolonged stress will eventually kill the cell.

Scientists bred a line of diabetes-predisposed mice without the Atf6 gene in their beta cells. Instead of meeting their typical fate, those mice were protected from diabetes. Analysis of the genes expressed by their beta cells suggested the cells entered a state called senescence far ahead of schedule.

Senescence is a period of the cell's life cycle in which it stops dividing and halts other normal cellular business. Senescing cells can cause problems for neighboring cells by releasing inflammatory messaging molecules that trigger an immune system response.

When researchers removed—knocked-out—the Atf6 gene in the beta cells in the pancreas of their mouse model of type 1 diabetes, and they did not become diabetic. Instead of dying off, these cells unexpectedly appear to go into an early senescence state that initiated a beneficial immune response and helped the cells survive an autoimmune attack.

DNA damage, stress and aging can kick off senescence, which can draw an immune system response that cleans up the senescent cells. If the immune system fails to clear these cells, they accumulate and cause chronic inflammation and disease.

The beta cells without Atf6 exhibit transient senescence and start releasing this group of proteins, including leukemia inhibitory factor, or LIF, that recruits protective immune cells called M2 macrophages.

Part 1

Comment by Dr. Krishna Kumari Challa on November 11, 2023 at 8:48am

Using bacteria to make lunar soil more fertile

A team of agronomists and biotechnicians  has found that adding bacteria to simulated lunar regolith increased the amount of phosphate in the soil for use by plants. In their study, published in the journal Communications Biology, the group added three types of bacteria to samples of volcanic material and then tested them for acidity and their ability to grow plants.

As several countries make plans to send humans back to the moon, they must address several issues—one of the most basic is figuring out a way to feed people working there for an extended period of time. The obvious solution is for workers to grow their own food. But that presents problems, as well, such as how to transport soil for growing edible plants from Earth to the moon.

Some have suggested that moon soil, known as lunar regolith, might be treated to make it amenable to plant growth. Last year, a team in the U.S. showed that it is possible to grow plants in lunar regolith by growing a small number of weeds called thale cress in real lunar soil samples. That test showed that lunar soil can work, but not well enough for plants to mature and produce food. In this new study, the research team found that adding microbes to lunar soil can improve its ability to host plant life. To test the possibility of using microbes such as bacteria to make lunar regolith more hospitable to plant life, the research team obtained samples of volcanic material from a mountain in China—testing showed it to be a reasonable stand-in for regolith. The researchers then added one of three types of bacteria to three test pots filled with the volcanic material: Pseudomonas fluorescens, Bacillus megaterium and Bacillus mucilaginosus. After cultivating the bacteria in the soil samples, the researchers tested the samples to see the effects. They found that the addition of all three types of bacteria had made the soil samples more acidic, which resulted in reducing the pH level of the soil. That dissolved the insoluble phosphate-containing minerals in the soil, which released phosphorus, making it available for plants.

Yitong Xia et al, Phosphorus-solubilizing bacteria improve the growth of Nicotiana benthamiana on lunar regolith simulant by dissociating insoluble inorganic phosphorus, Communications Biology (2023). DOI: 10.1038/s42003-023-05391-z

Comment by Dr. Krishna Kumari Challa on November 10, 2023 at 1:45pm

Engineered yeast breaks new record: a genome with over 50% synthetic DNA

Highly edited strain survives and replicates despite containing 7.5 artificial chromosomes.

Scientists have created a strain of brewer’s yeast (Saccharomyces cerevisiae) whose genome is more than half synthetic. Seven-and-a-half chromosomes were synthesized or stitched together in the laboratory. To make sure the genome was stable, biologists removed repetitive regions of DNA and sequestered all genes for transfer RNAs — essential for protein synthesis — in a single ‘neochromosome’. It’s a milestone for the Sc2.0 consortium, whose aim is to create yeast with a fully synthetic genome.

https://www.sciencedirect.com/science/article/pii/S0092867423011303...

https://www.cell.com/cell-genomics/fulltext/S2666-979X(23)00273-2?utm_source=Live+Audience&utm_campaign=3a61cb3609-briefing-dy-20231109&utm_medium=email&utm_term=0_b27a691814-3a61cb3609-50323416

Comment by Dr. Krishna Kumari Challa on November 10, 2023 at 1:33pm

Blood cancer treatment could be transformed by discovery

Comment by Dr. Krishna Kumari Challa on November 9, 2023 at 8:53am

This is how the scientists described their work:

After we prepared the hydrogel, we embedded photosynthetic—or sunlight-capturing—bacteria called cyanobacteria into the gel.

The cyanobacteria embedded in the material still needed to take in light and carbon dioxide to perform photosynthesis, which keeps them alive. The hydrogel was porous enough to allow that, but to make the configuration as efficient as possible, we 3D-printed the gel into custom shapes—grids and honeycombs. These structures have a higher surface-to-volume ratio that allow more light, CO₂ and nutrients to come into the material.
Like all other bacteria, cyanobacteria has different genetic circuits, which tell the cells what outputs to produce. Our team genetically engineered the bacterial DNA so that the cells created a specific enzyme called laccase.

The laccase enzyme produced by the cyanobacteria works by performing a chemical reaction with a pollutant that transforms it into a form that's no longer functional. By breaking the chemical bonds, it can make a toxic pollutant nontoxic. The enzyme is regenerated at the end of the reaction, and it goes off to complete more reactions.

 Debika Datta et al, Phenotypically complex living materials containing engineered cyanobacteria, Nature Communications (2023). DOI: 10.1038/s41467-023-40265-2

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