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Comment by Dr. Krishna Kumari Challa on September 23, 2020 at 8:28am

Without oxygen, Earth's early microbes relied on arsenic to sustain life

Much of life on planet Earth today relies on oxygen to exist, but before oxygen was present on our blue planet, lifeforms likely used arsenic instead. These findings are detailed in research published recently.

A key component of the oxygen cycle is where plants and some types of bacteria essentially take sunlight, water, and CO₂, and convert them to carbohydrates and oxygen, which are then cycled and used by other organisms that breathe oxygen. This oxygen serves as a vehicle for electrons, gaining and donating electrons as it powers through the metabolic processes. However, for half of the time life has existed on Earth, there was no oxygen present, and for the first 1.5 billion years.

Light-driven, photosynthetic organisms appear in the fossil record as layered carbonate rocks called stromatolites dating to around 3.7 billion years ago, says Visscher. Stromatolite mats are deposited over the eons by microbial ecosystems, with each layer holding clues about life at that time. There are contemporary examples of microbes that photosynthesize in the absence of oxygen using a variety of elements to complete the process, however it's unclear how this happened in the earliest life forms.

Theories as to how life's processes functioned in the absence of oxygen have mostly relied on hydrogen, sulfur, or iron as the elements that ferried electrons around to fulfill the metabolic needs of organisms. These theories were contested though.

Arsenic is another theoretical possibility, and evidence for that was found in 2008.The link with arsenic was strengthened in 2014 when researchers found evidence of arsenic-based photosynthesis in deep time.

 found a blood red river. The red sediments are made up by anoxogenic photosynthetic bacteria. The water is very high in arsenic as well. The water that flows over the mats contains hydrogen sulfide that is volcanic in origin and it flows very rapidly over these mats. There is absolutely no oxygen."

The team also showed that the mats were making carbonate deposits and creating a new generation of stromatolites. The carbonate materials also showed evidence for arsenic cycling—that arsenic is serving as a vehicle for electrons—proving that the microbes are actively metabolizing arsenic, much like oxygen in modern systems. Visscher says these findings, along with the fossil evidence, gives a strong sense of the early conditions of Earth.

Pieter T. Visscher et al. Modern arsenotrophic microbial mats provide an analog for life in the anoxic Archean, Communications Earth & Environment (2020). DOI: 10.1038/s43247-020-00025-2

https://phys.org/news/2020-09-oxygen-earth-early-microbes-arsenic.h...

Comment by Dr. Krishna Kumari Challa on September 23, 2020 at 8:07am

New finding: Why some cancers may respond poorly to key drugs 

Patients with BRCA1/2 mutations are at higher risk for breast, ovarian and prostate cancers that can be aggressive when they develop—and, in many cases, resistant to lifesaving drugs. Now scientists  have identified a driver of the drug resistance that can make a life or death difference for patients with these cancers.

A major issue with cancer treatments is the development of resistance. When treatments stop working for patients, it's incredibly demoralizing and it's been a huge drive in research to understand these resistance mechanisms.

In a new paper published, researchers describe a protein that may help doctors predict which patients will become resistant to a class of drugs frequently used to treat BRCA 1/2-deficient tumours. The finding could help create more effective treatment plans for their patients.

The scientists identified that a protein called PCAF promotes DNA damage in BRCA 1/2-mutated cancer cells. Patients with low levels of this protein are likely to have poor outcomes and develop resistance to a type of drug that is used to treat BRCA-deficient tumors, called a PARP inhibitor.

PARP inhibitors are an important breakthrough in treating these aggressive cancers. What the researchers  found now 's that when levels of PCAF are low, it actually protects the cancer cells from this drug. By testing biopsy samples, doctors may be able to tell using PCAF as a molecular marker for PARP inhibitor responses what treatment may work best for a patient."

Fortunately, there is already another class of drugs on the market, called HDAC inhibitors, that can boost the effectiveness of the PCAF protein. HDAC inhibitors and PARP inhibitors have the potential to be prescribed as a combination therapy.

Molecular Cell (2020). DOI: 10.1016/j.molcel.2020.08.018

https://medicalxpress.com/news/2020-09-cancers-poorly-key-drugs.htm...

Comment by Dr. Krishna Kumari Challa on September 23, 2020 at 6:29am

New drug candidate found for hand, foot and mouth disease

A study  offers some good news in the search for antiviral drugs for hard-to-treat diseases. Researchers have identified a potential new drug candidate against enterovirus 71, a common cause of hand, foot and mouth disease in infants and young children. While most people get better within 7 to 10 days after suffering little more than a fever and rash, severe cases can cause brain inflammation, paralysis and even death.

The compound of interest is a small molecule that binds to RNA, the virus's genetic material, and changes its 3-D shape in a way that stops the virus from multiplying without harming its human host.

"Small Molecule Targeting IRES Domain Inhibits Enterovirus 71 Replication via an Allosteric Mechanism that Stabilizes a Ternary Complex," Nature Communications (2020). DOI: 10.1038/s41467-020-18594-3

https://medicalxpress.com/news/2020-09-drug-candidate-foot-mouth-di...

Comment by Dr. Krishna Kumari Challa on September 23, 2020 at 6:24am

Scientists identify hormone that might help treat malabsorption

Scientists  used human intestinal organoids grown from stem cells to discover how our bodies control the absorption of nutrients from the food we eat. They further found that one hormone might be able to reverse a congenital disorder in babies who cannot adequately absorb nutrients and need intravenous feeding to survive.

Researchers found that the hormone peptide YY, also called PYY, can reverse congenital malabsorption in mice. With a single PYY injection per day, 80% of the mice survived. Normally, only 20% to 30% survive. This indicates PYY might be a possible therapeutic for people with severe malabsorption.

Poor absorption of macronutrients is a global health concern, underlying ailments such as malnutrition, intestinal infections and short-gut syndrome. So, identification of factors regulating nutrient absorption has significant therapeutic potential. Scientists reported that the absorption of nutrients—in particular, carbohydrates and proteins—is controlled by enteroendocrine cells  in the gastrointestinal tract.

Babies born without enteroendocrine cells —or whose enteroendocrine cells don't function properly—have severe malabsorption and require IV nutrition. This work could help them.

Enteroendocrine cells couple nutrient sensing to nutrient absorption by regulating ion transport," Nature Communications (2020). DOI: 10.1038/s41467-020-18536-z

https://medicalxpress.com/news/2020-09-scientists-hormone-malabsorp...

Comment by Dr. Krishna Kumari Challa on September 23, 2020 at 6:07am

Evolution of radio-resistance is very complicated 

The toughest organisms on Earth, called extremophiles, can survive extreme conditions like extreme dryness (desiccation), extreme cold, space vacuum, acid, or even high-level radiation. So far, the toughest of all seems to be the bacterium Deinococcus radiodurans—able to survive doses of radiation a thousand times greater than those fatal to humans. 

How this radio-resistance could have evolved in several organisms on our planet, naturally protected from solar radiation by its magnetic field? While some scientists suggest that radio-resistance in extremophile organisms could have evolved along with other kinds of resistance, such as resistance to desiccation, a question remained: which genes are specifically involved in radio-resistance?

To find out the researchers started with the naturally non-resistant bacteria, E. coli, and exposed it to iterative cycles of high-level irradiation. After many rounds of radiation exposure and outgrowth, a few radio-resistant populations emerged. Using whole-genome sequencing, the researchers studied the genetic alterations present in each radio-resistant population and determined which mutation provided radio-resistance to the bacteria.

The study of their genetic profile highlighted three mutations responsible for radio-resistance—all in genes linked to DNA repair mechanisms. The results show that the populations of radioresistant E. coli, continued to evolve and sub-populations emerged. Surprisingly, while radio-resistance induced by the first series of ionization could mainly be associated with three mutations, the second induced hundreds of mutations including large deletions and duplications of several genes. The four populations scienitsts are evolving in this new trial have now achieved levels of radio-resistance that are approaching the levels seen with Deinococcus radiodurans. As the current trial has progressed, the genomic alterations have proven to be much more complex than anticipated.

The researchers show that more cellular metabolisms are affected (ATP synthesis, iron-sulfur cluster biogenesis, cadaverine synthesis, and reactive oxygen species response). Furthermore, this study proves that radio-resistance can develop to the level of Deinococcus radiodurans, independently to desiccation-resistance. 

As the exposition to radiation and experimental evolution continues, more data are gathered on how to induce radio-resistance in bacteria. This could one day constitute a precious toolbox of mutations to engineer radioresistant probiotics helping for example patients treated with radiotherapy, or astronauts exposed to space radiation.

 Frontiers in Microbiology, DOI: 10.3389/fmicb.2020.582590 , www.frontiersin.org/articles/1 … 2020.582590/abstract

https://phys.org/news/2020-09-evolution-radio-resistance-complicate...

Comment by Dr. Krishna Kumari Challa on September 22, 2020 at 6:26am

Solstices and equinoxes are the products of Earth's axial tilt: the degree to which the planet is tilted relative to the Sun.

The axis around which the Earth spins isn't straight up and down - it's about 23.5 degrees off. Because of that, different parts of the Earth get exposed to more or less sunlight as the planet rotates around the Sun. That's why we have seasons.

It's also why the northern and Southern Hemisphere experience seasons at opposite times: During winter in the Northern Hemisphere, the Southern Hemisphere is tilted more towards the Sun, and vice versa.

Meanwhile, Earth is also constantly rotating, which keeps its heating even - kind of like a planet-sized rotisserie chicken twisting over a spit.

The axial tilt's most dramatic effect comes during the solstices, since those are the two days when one side of the planet is tilted the farthest away from the Sun and the other is the closest. On December 21, the Northern Hemisphere receives less than nine hours of daylight, while the Southern Hemisphere receives more than 15.

https://www.sciencealert.com/the-september-equinox-is-this-tuesday-...

Comment by Dr. Krishna Kumari Challa on September 22, 2020 at 6:20am

How your brain finds the good objects

How your brain finds the good objects

In the wild, it is essential for animals to pick out good or bad objects within their visual field. Whether it be food or predator, split-second recognition and action need to be made for survival.

https://researchnews.cc/news/2629/How-your-brain-finds-the-good-obj...

The underlying mechanisms that govern this behavior in the brain has been gradually uncovered by researchers. Nowscientists have revealed how the brain controls eye movements toward the 'good objects'.

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Seismic data explains continental collision beneath Tibet

https://phys.org/news/2020-09-seismic-continental-collision-beneath...

Comment by Dr. Krishna Kumari Challa on September 22, 2020 at 6:17am

Giant spider provides promise of pain relief for irritable bowel syndrome

Comment by Dr. Krishna Kumari Challa on September 22, 2020 at 5:40am

**‘I didn’t mean to hurt you’: new research shows funnel webs don’t set out to kill humans

https://theconversation.com/i-didnt-mean-to-hurt-you-new-research-s...

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Mass Elephant Deaths in Botswana Caused By Bacteria Toxin In Waterholes

The mysterious deaths of at least 330 elephants in Botswana this year was caused by cyanobacteria-infected water, say wildlife officials. There are still many unanswered questions, including why only elephants seem to have been affected and why this mostly occurred in one region. 

https://www.bloomberg.com/news/articles/2020-09-21/botswana-says-ma...

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Are Humans Still Evolving? Find out ….

https://www.sciencealert.com/are-humans-still-evolving

Comment by Dr. Krishna Kumari Challa on September 22, 2020 at 5:25am

Defying a 150-year-old rule for phase behaviour

Frozen water can take on up to three forms at the same time when it melts: liquid, ice and gas. This principle, which states that many substances can occur in up to three phases simultaneously, was explained 150 years ago by the Gibbs phase rule. Now researchers  are defying this classical theory, with proof of a five-phase equilibrium, something that many scholars considered impossible.

Gibbs' thermodynamics rule: If we take water as an example, there is one point, with a specific temperature and pressure, where water occurs as gas, liquid and ice at the same time, the so-called triple point.

But researchers   now show that in this mixture, there is a whole series of circumstances in which four phases exist at the same time. There is even one point at which there are five coexisting phases—two too many.

 At that specific point, also called a five-phase equilibrium, a gas phase, two liquid crystal phases, and two solid phases with 'ordinary' crystals exist simultaneously. And that has never been seen before. This is the first time that the famous Gibbs rule has been broken.

The crux lies in the shape of the particles in the mixture. scientists now show that it is precisely the specific length and diameter of the particles that play a major role.

In addition to the known variables of temperature and pressure, you get two additional variables: the length of the particle in relation to its diameter, and the diameter of the particle in relation to the diameter of other particles in the solution.

V. F. D. Peters et al, Defying the Gibbs Phase Rule: Evidence for an Entropy-Driven Quintuple Point in Colloid-Polymer Mixtures, Physical Review Letters (2020). DOI: 10.1103/PhysRevLett.125.127803

https://phys.org/news/2020-09-defying-year-old-phase-behavior.html?...

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