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Comment by Dr. Krishna Kumari Challa on August 5, 2021 at 8:22am

Virtually all the energy in the Earth's climate system comes from the sun. Only a tiny fraction is conducted upward from the Earth's interior.

On average, the planet receives 340.4 watts of sunshine per square meter. All sunshine falls on the daytime side, and the numbers are much higher at local noon.

Of that 340.4 watts per square meter:
99.9 watts are reflected back into space by clouds, dust, snow and the Earth's surface.
The remaining 240.5 watts are absorbed—about a quarter by the atmosphere and the rest by the surface of the planet. This radiation is transformed into thermal energy within the Earth system. Almost all of this absorbed energy is matched by energy emitted back into space. A tiny residual—0.6 watts per square meter—accumulates as global warming. That may not sound like much, but it adds up.
The atmosphere absorbs a lot of energy and emits it as radiation both into space and back down to the planet's surface. In fact, Earth's surface gets almost twice as much radiation from the atmosphere as it does from direct sunshine. That's primarily because the sun heats the surface only during the day, while the warm atmosphere is up there 24/7.

part 2

Comment by Dr. Krishna Kumari Challa on August 5, 2021 at 8:21am

Earth's energy budget is out of balance – here's how it's warming the climate

Energy can neither be created nor destroyed. That's a fundamental property of the universe.

Energy can be transformed, however. When the sun's rays reach Earth, they are transformed into random motions of molecules that you feel as heat. At the same time, Earth and the atmosphere are sending radiation back into space. The balance between the incoming and outgoing energy is known as Earth's "energy budget."

Our climate is determined by these energy flows. When the amount of energy coming in is more than the energy going out, the planet warms up.

That can happen in a few ways, such as when sea ice that normally reflects solar radiation back into space disappears and the dark ocean absorbs that energy instead. It also happens when greenhouse gases build up in the atmosphere and trap some of the energy that otherwise would have radiated away.

part 1

Comment by Dr. Krishna Kumari Challa on August 5, 2021 at 7:46am

Study reveals how smell receptors work

All senses must reckon with the richness of the world, but nothing matches the challenge faced by the olfactory system that underlies our sense of smell. We need only three receptors in our eyes to sense all the colors of the rainbow—that's because different hues emerge as light-waves that vary across just one dimension, their frequency. The vibrant colorful world, however, pales in comparison to the complexity of the chemical world, with its many millions of odors, each composed of hundreds of molecules, all varying greatly in shape, size and properties. The smell of coffee, for instance, emerges from a combination of more than 200 chemical components, each of which are structurally diverse, and none of which actually smells like coffee on its own.

To form a basic understanding of odorant recognition we need to know how a single receptor can recognize multiple different chemicals, which is a key feature of how the olfactory system works 

The olfactory system has to recognize a vast number of molecules with only a few hundred odour receptors or even less. It's clear that it had to evolve a different kind of logic than other sensory systems.

In a new study researchers offer answers to the decades-old question of odour recognition by providing the first-ever molecular views of an olfactory receptor at work.

The findings, published in Nature, reveal that olfactory receptors indeed follow a logic rarely seen in other receptors of the nervous system. While most receptors are precisely shaped to pair with only a few select molecules in a lock-and-key fashion, most olfactory receptors each bind to a large number of different molecules. Their promiscuity in pairing with a variety of odors allows each receptor to respond to many chemical components. From there, the brain can figure out the odor by considering the activation pattern of combinations of receptors.

 The structural basis of odorant recognition in insect olfactory receptors, Nature (2021). DOI: 10.1038/s41586-021-03794-8 , www.nature.com/articles/s41586-021-03794-8

https://phys.org/news/2021-08-reveals-receptors.html?utm_source=nwl...

Comment by Dr. Krishna Kumari Challa on August 5, 2021 at 5:58am

Driverless Tractor: India’s Innovation

Comment by Dr. Krishna Kumari Challa on August 4, 2021 at 10:39am

Cryptic transcription in mammalian stem cells linked to aging

Although visible signs of aging are usually unmistakable, unraveling what triggers them has been quite a challenge. Researchers have discovered that a cellular phenomenon called cryptic transcription, which had been previously described and linked to aging in yeasts and worms, is elevated in aging mammalian stem cells.

Researchers report in the journal Nature Aging that cryptic transcription occurs because a cellular mechanism that keeps it in check falls apart as cells get old. The findings suggest that strategies that control cryptic transcription could have pro-longevity effects.

In previous work, they showed that cryptic transcription in yeasts and worms is not only a marker of aging but also a cause. Reducing the amount of this aberrant transcription in these organisms prolonged their lifespan.

Cryptic transcription is a phenomenon that interferes with normal cellular processes. Normal gene transcription is a first step in the production of proteins. It begins in a specific location on the DNA called the promoter. This is where the protein coding gene begins to be transcribed into RNA, which is eventually translated into protein. Gene transcription is a well-regulated cellular process, but as cells age, they lose their ability to control it.

Promoters have a specific DNA sequence that identifies the starting point of the transcription process that is usually located preceding the actual protein coding sequence.

But promoter look-alike sequences do exist in other locations, including along the actual protein coding sequence, and they could start transcription and generate shorter transcripts, called cryptic transcripts.

worked with mammalian stem cells, which have shown to play a significant role in aging. They adapted a method to detect cryptic transcription to determine the level of this transcription in mice and human stem cells and cultured cells. When compared to young stem cells, older ones had increased cryptic transcription. They also looked into other aging cells and found that, in the majority of cells spanning a range of tissues, cryptic transcription was also elevated with age.

Altogether, these findings indicate that elevated cryptic transcription is a hallmark of mammalian aging. Young cells have mechanisms in place to prevent cryptic transcription. In aged mammalian cells, the researchers found that one such mechanisms, which involves limiting the access to chromatin, the material that makes up the chromosomes, is failing, facilitating the production of cryptic transcripts.

https://www.nature.com/articles/s43587-021-00091-x

https://researchnews.cc/news/8148/Cryptic-transcription-in-mammalia...

Comment by Dr. Krishna Kumari Challa on August 4, 2021 at 10:13am

Particles from paints, pesticides can have deadly impact

Hundreds of thousands of people around the world die too soon every year because of exposure to air pollution caused by our daily use of chemical products and fuels, including paints, pesticides, charcoal and gases from vehicle tailpipes, according to a new study.

Researchers calculated that air pollution caused by "anthropogenic secondary organic aerosol" causes 340,000-900,000 premature deaths. Those are tiny particles in the atmosphere that form from chemicals emitted by human activities.

The older idea was that to reduce premature mortality, you should target coal-fired power plants or the transportation sector. Yes, these are important, but this study is showing that if you're not getting at the cleaning and painting products and other everyday chemicals, then you're not getting at a major source.

Atmospheric researchers have long understood that particles in the atmosphere small enough to be inhaled can damage people's lungs and increase mortality. Studies have estimated that fine particle pollution, often called PM2.5, leads to 3-4 million premature deaths  globally per year, possibly more.

The new work suggests that a third broad category of chemicals—anthropogenic secondary organic pollutants—is a significant indirect source of deadly fine particles.

Benjamin A. Nault et al, Secondary organic aerosols from anthropogenic volatile organic compounds contribute substantially to air pollution mortality, Atmospheric Chemistry and Physics (2021). DOI: 10.5194/acp-21-11201-2021

https://phys.org/news/2021-08-particles-pesticides-deadly-impact.ht...

Comment by Dr. Krishna Kumari Challa on August 4, 2021 at 9:33am

How sex cells get the right genetic mix

A new discovery explains what determines the number and position of genetic exchanges that occur in sex cells, such as pollen and eggs in plants, or sperm and eggs in humans.

When sex cells are produced by a special cell division called meiosis, chromosomes exchange large segments of DNA. This ensures that each new cell has a unique genetic makeup and explains why, with the exception of identical twins, no two siblings are ever completely genetically alike. These exchanges of DNA, or crossovers, are essential for generating genetic diversity, the driving force for evolution, and their frequency and position along chromosomes are tightly controlled.

Crossover positioning has important implications for evolution, fertility and selective breeding. By understanding the mechanisms that drive crossover positioning we are more likely to be able to uncover methods to modify crossover positioning to improve current plant and animal breeding technologies.

A research team studied the behavior of a protein called HEI10 which plays an integral role in crossover formation in meiosis. Super-resolution microscopy revealed that HEI10 proteins cluster along chromosomes, initially forming lots of small groups. However, as time passes, the HEI10 proteins concentrate in only a small number of much larger clusters which, once they reach a critical mass, can trigger crossover formation.

These measurements were then compared against a mathematical model which simulates this clustering, based on diffusion of the HEI10 molecules and simple rules for their clustering. The mathematical model was capable of explaining and predicting many experimental observations, including that crossover frequency could be reliably modified by simply altering the amount HEI10.

This study shows that data from super-resolution images of Arabidopsis reproductive cells is consistent with a mathematical 'diffusion-mediated coarsening' model for crossover patterning in Arabidopsis. The model helps us understand the patterning of crossovers along meiotic chromosomes.

Diffusion-mediated HEI10 coarsening can explain meiotic crossover positioning in Arabidopsis" appears in Nature Communications.

Diffusion-mediated HEI10 coarsening can explain meiotic crossover positioning in Arabidopsis, Nature Communications (2021). DOI: 10.1038/s41467-021-24827-w

https://phys.org/news/2021-08-sex-cells-genetic-interdisciplinary-a...

Comment by Dr. Krishna Kumari Challa on August 3, 2021 at 8:46am

Traumatic brain injury research

Comment by Dr. Krishna Kumari Challa on August 3, 2021 at 8:39am

Deficiency in how gut microbiome-produced substances are detected in high blood pressure

In a new study  scientists have found that microbial genetic pathways are different in people suffering from hypertension.

The research also found that those with hypertension also have a deficiency in a newly identified target gene that senses gut microbiota-derived metabolites that lower BP.

If left untreated, hypertension, also referred to as high BP, can lead to stroke and, myocardial infarction, the main causes of death globally. Long-term, hypertension causes a stiffening of the arteries and the muscles of the heart, leading to heart failure. This is important as the research team also found in another recently published study that patients with heart failure, for which hypertension is a major risk factor, have a distinct gut microbiome composition.

The research team assessed human gut microbiota in the setting of high blood-pressure levels and heart failure to better understand the complex nature of these diseases. Changes in gut microbiome were particularly associated with bacteria that are known to produce short-chain fatty acids, substances their team has previously shown to ameliorate blood pressure and heart disease in mice.

The researchers found that the gut microbiome was mostly similar between normotensive and essential hypertensive groups, but the gut microbial gene pathways were different, suggesting major differences in the function of the microbiota.

They also found that hypertensive subjects have a deficiency in a new target gene that senses gut microbiota derived metabolites that lower blood pressure.

 Michael Nakai et al, Essential Hypertension Is Associated With Changes in Gut Microbial Metabolic Pathways, Hypertension (2021). DOI: 10.1161/HYPERTENSIONAHA.121.17288

Anna L. Beale et al, The Gut Microbiome of Heart Failure With Preserved Ejection Fraction, Journal of the American Heart Association (2021). DOI: 10.1161/JAHA.120.020654

https://medicalxpress.com/news/2021-08-deficiency-gut-microbiome-pr...

Comment by Dr. Krishna Kumari Challa on August 3, 2021 at 8:33am

Male fertility is declining, environmental toxins could be a reason

A wide range of factors—from obesity to hormonal imbalances to genetic diseases—can affect fertility. For many men, there are treatments that can help. But starting in the 1990s, researchers noticed a concerning trend. Even when controlling for many of the known risk factors, male fertility appeared to have been declining for decades. In 1992, a study found a global 50% decline in sperm counts in men over the previous 60 years. Multiple studies over subsequent years confirmed that initial finding, including a 2017 paper showing a 50% to 60% decline in sperm concentration between 1973 and 2011 in men from around the world. The science is consistent: Men today produce fewer sperm than in the past, and the sperm are less healthy. The question, then, is what could be causing this decline in fertility. Scientists have known for years that, at least in animal models, environmental toxic exposure can alter hormonal balance and throw off reproduction. Researchers can't intentionally expose human patients to harmful compounds and measure outcomes, but we can try to assess associations. As the downward trend in male fertility emerged, I and other researchers began looking more toward chemicals in the environment for answers. This approach doesn't allow us to definitively establish which chemicals are causing the male fertility decline, but the weight of the evidence is growing. A lot of this research focuses on endocrine disrupters, molecules that mimic the body's hormones and throw off the fragile hormonal balance of reproduction. These include substances like phthalates—better known as plasticizers—as well as pesticides, herbicides, heavy metals, toxic gases and other synthetic materials. Plasticizers are found in most plastics—like water bottles and food containers—and exposure is associated with negative impacts on testosterone and semen health.Herbicides and pesticides abound in the food supply and some—specifically those with synthetic organic compounds that include phosphorus—are known to negatively affect fertility. Air pollution surrounds cities, subjecting residents to particulate matter, sulfur dioxide, nitrogen oxide and other compounds that likely contribute to abnormal sperm quality. Radiation exposure from laptops, cellphones and modems has also been associated with declining sperm counts, impaired sperm motility and abnormal sperm shape. Heavy metals such as cadmium, lead and arsenic are also present in food, water and cosmetics and are also known to harm sperm health. Endocrine-disrupting compounds and the infertility problems they cause are taking a significant toll on human physical and emotional health. And treating these harms is costly.

https://theconversation.com/male-fertility-is-declining-studies-sho...

https://medicalxpress.com/news/2021-08-male-fertility-declining-env...

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