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Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 10:28am

Human Cells Can Synthesize DNA in Their Cytoplasm

While studying a degenerative eye disease, researchers find the first evidence that cells produce endogenous DNA in the cytoplasm. Drugs that block this activity are linked with reduced risk of atrophic age-related macular degeneration.

Over the past decade, there have been scattered reports of mammalian cells’ own DNA being found in the cytoplasm, mainly in the context of disease and aging. While it is not unusual to find DNA from an invading organism there, the presence of an organism’s own genetic code—in the form of complementary DNA (cDNA) synthesized from an RNA template—has puzzled scientists. In each case, the cDNA has come from endogenous retrotransposons, known for their copy-and-paste mechanism that results in the insertion of new copies of themselves into the genome. This process typically takes place in the nucleus, so the cytoplasmic cDNA lacked an explanation.

After detecting cDNA of Alu, the most abundant retrotransposon in the human genome, in the cytoplasm of cells modeling a degenerative eye disease, University of Virginia ophthalmologist Jayakrishna Ambati and his colleagues decided to investigate its mysterious origin. Their results, reported February 1 in PNAS, reveal that human cells can actually synthesize cDNA of Alu in the cytoplasm.

S. Fukuda et al., “Cytoplasmic synthesis of endogenous Alu complementary DNA via reverse transcription and implications in age-related macular degeneration,” PNAS, doi:10.1073/pnas.2022751118, 2021.

Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 10:13am

An Optical Coating Like No Other

Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 10:09am

Synchronization of brain hemispheres changes what we hear

How come we don’t hear everything twice: After all, our ears sit on opposite sides of our head and most sounds do not reach both our ears at exactly the same time. While this helps us determine which direction sounds are coming from, it also means that our brain has to combine the information from both ears. Otherwise, we would hear an echo.

In addition, input from the right ear reaches the left brain hemisphere first, while input from the left ear reaches the right brain hemisphere first. The two hemispheres perform different tasks during speech processing: The left side is responsible for distinguishing phonemes and syllables, whereas the right side recognizes the speech prosody and rhythm. Although each hemisphere receives the information at a different time and processes different features of speech, the brain integrates what it hears into a unified speech sound.

The exact mechanism behind this integration process was not known until now. 

Now researchers have managed to demonstrate that the process of integrating what we hear is directly linked to synchronization by gamma waves.

During the experiments, the researchers disrupted the natural activity pattern of gamma waves by stimulating both hemispheres of the brain with electrodes attached to the head. This manipulation affected participants’ ability to correctly identify the syllable they heard. The fMRI analysis showed that there were also changes in the activity of the neural connections between the right and the left brain hemispheres: The strength of the connection changed depending on whether the rhythm of the gamma waves was influenced by electric stimulation in the two brain hemispheres synchronously or asynchronously. This disruption also impaired the integration process. Thus, synchronization of the gamma waves seems to serve to balance the different inputs from the two hemispheres of the brain, providing a unified auditory impression.

These findings could thus also find clinical application in the near future. “Previous studies show that disturbances in the connection between the two hemispheres of the brain are associated with auditory phantom perceptions such as tinnitus and auditory verbal hallucinations. Thus, electric brain stimulation may present a promising avenue for the development of therapeutic interventions.

Preisig BC, Riecke L, Sjerps M, Kösem A, Kop BR, Bramson B, Hagoort P, Hervais-Adelman A. Selective modulation of interhemispheric connectivity by transcranial alternating current stimulation influences binaural integration. PNAS, 2021 DOI: 10.1073/pnas.2015488118

https://www.sciencedaily.com/releases/2021/02/210208173103.htm#:~:t....

https://researchnews.cc/news/5061/Synchronization-of-brain-hemisphe...

Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 9:08am

A reeking, parasitic plant lost its body and much of its genetic blueprint

The genome of Sapria himalayana is rife with gene loss and theft

New research on the genetic instruction book of a rare plant Sapria genus reveals the lengths to which it has gone to become a specialized parasite. The findings, published January 22 in Current Biology, suggest that at least one species of Sapria has lost nearly half of the genes commonly found in other flowering plants and stolen many others directly from its hosts. 

The plant’s rewired genetics echo its bizarre biology. Sapria and its relatives in the family Rafflesiaceae have discarded their stems, roots and any photosynthetic tissue.

About 44 percent of the genes found in most flowering plants were missing in S. himalayana. Yet, at the same time, the genome is about 55,000 genes long, more than that of some other nonparasitic plants. The count is inflated by many repeating segments of DNA, the team found.

Loss of the chlorophyll pigments responsible for photosynthesis is common in parasitic plants that rely on their hosts for sustenance. But S. himalayana appears to have even scrapped all genetic remnants of its chloroplasts, the cellular structures where photosynthesis occurs. 

Chloroplasts have their own genome, distinct from the nuclear genome that runs a plant’s cells and the mitochondria that produce energy for the cells. S. himalayana seems to have lost this genome altogether, suggesting that the plant has purged the last remnants of its ancestral life that allowed it to make its own food.

even genes in S. himalayana’s nuclear genome that would regulate components of the chloroplast genome have vanished. 

Among the remaining parts of the nuclear genome, it was  also found that more than 1 percent of S. himalayana’s genome comes from genes stolen from other plants, likely its current and ancestral hosts.

The new discovery illustrates the level of commitment S. himalayana and its relatives have given to evolving a parasitic lifestyle

https://www.cell.com/current-biology/fulltext/S0960-9822(20)31897-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982220318972%3Fshowall%3Dtrue

https://www.sciencenews.org/article/reeking-parasitic-sapria-plant-...

Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 9:02am

Reconstructing Molecules in Motion

Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 8:16am

Our Milky Way galaxy is a spiral galaxy. It evolved into its flat disk shape over billions of years. But astronomers have discovered a distant and young galaxy that has a remarkably similar shape.

Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 8:10am

Air pollution caused 1 out of 5 deaths in 2018—that's more than 8 million, study says

Microscopic, and sometimes larger, particles of soot, smoke and dust that spew out of gas-guzzling factories, ships, cars and aircraft are responsible for 18% of total global deaths in 2018—that equals more than 8 million people, a new study found.

That number far surpasses previous estimates of the amount of people killed globally by all types of air pollution, including dust and smoke from wildfires and agricultural burns. The most widely accepted estimate stands at 4.2 million.

https://phys.org/news/2021-02-air-pollution-deaths-2018that-million...

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How microplastics in the soil contribute to environmental pollution

Plastic, with its unabated global production, is a major and persistent contributor to environmental pollution. In fact, the accumulation of plastic debris in our environment is only expected to increase in the future. "Microplastics" (MP)—plastic debris

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A new way of forming planets

In the last 25 years, scientists have discovered over 4000 planets beyond the borders of our solar system. From relatively small rock and water worlds to blisteringly hot gas giants, the planets display a remarkable variety. This variety is not unexpected. The sophisticated computer models, with which scientists study the formation of planets, also spawn very different planets. What the models have more difficulty to explain is the observed mass distribution of the planets discovered around other stars. The majority have fallen into the intermediate mass category—planets with masses of several Earth masses to around that of Neptune. Even in the context of the solar system, the formation of Uranus and Neptune remains a mystery. Scientists of the Universities of Zurich and Cambridge, associated with the Swiss NCCR PlanetS, have now proposed an alternative explanation backed up by comprehensive simulations. Their results were published in the scientific journal Nature Astronomy.

Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 8:07am

Tiny microorganisms in the Southern Ocean affect how the rest of the world's seas respond to carbon

In the ocean that surrounds Antarctica, deep water wells up to the surface, carrying nutrients and other dissolved materials needed by light-loving ocean life. One of these materials is calcium carbonate, which, when dissolved, raises seawater alkalinity and helps the ocean respond to increasing carbon dioxide levels. Ocean currents carry this alkalinity-enriched water northward—unless tiny organisms intercept it and trap the alkalinity in the Southern Ocean.

Plankton in the Southern Ocean capture upwelled alkalinity to make protective shells composed of calcium carbonate. When the plankton die, their calcified shells sink and break down, returning the alkalinity to deep waters, from where it can well up again. If calcifying organisms are not very active, more high-alkalinity water escapes northward, allowing the global ocean to absorb more carbon dioxide. If, on the other hand, the calcifying plankton quickly use alkalinity that rises to the surface, this cycle traps alkalinity in the Southern Ocean.

Researchers recently  demonstrated this process through model simulations, showing that calcification in the Southern Ocean affects how alkalinity spreads around the world.

In general, more calcifying activity traps alkalinity in the Southern Ocean, but certain conditions limit the main phytoplankton responsible. For instance, high levels of silicic acid and iron might favor silicon-shelled microorganisms over calcium carbonate-shelled ones, allowing more alkalinity to flow out to other oceans. High ocean acidity may also cause problems for calcifying organisms.

The researchers note that after an interruption in calcification in the Southern Ocean, increases in alkalinity reached some subtropical regions within 10 years. The alkalinity irregularity took longer to reach more northerly oceans, gradually becoming more apparent the longer that Southern Ocean calcification was suppressed. On millennial timescales, the authors say, the activity of tiny southern plankton has the potential to influence global climate.

 K. M. Krumhardt et al. Southern Ocean Calcification Controls the Global Distribution of Alkalinity, Global Biogeochemical Cycles (2020). DOI: 10.1029/2020GB006727

https://phys.org/news/2021-02-tiny-microorganisms-southern-ocean-af...

Comment by Dr. Krishna Kumari Challa on February 12, 2021 at 7:41am

To find an extraterrestrial civilization, pollution could be the solution, NASA study suggests

If there's an advanced extraterrestrial civilization inhabiting a nearby star system, we might be able to detect it using its own atmospheric pollution, according to new NASA research. The study looked at the presence of nitrogen dioxide gas (NO₂), which on Earth is produced by burning fossil fuels but can also come from non-industrial sources such as biology, lightning, and volcanoes.

On Earth, most of the nitrogen dioxide is emitted from human activity—combustion processes such as vehicle emissions and fossil-fueled power plants. In the lower atmosphere (about 10 to 15 kilometers or around 6.2 to 9.3 miles), NO₂ from human activities dominate compared to non-human sources. Therefore, observing NO₂ on a habitable planet could potentially indicate the presence of an industrialized civilization.

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Astronomers have found over 4,000 planets orbiting other stars to date. Some might have conditions suitable for life as we know it, and on some of these habitable worlds, life may have evolved to the point where it produces a technological civilization. Since planets around other stars (exoplanets) are so far away, scientists cannot look for signs of life or civilization by sending spacecraft to these distant worlds. Instead, they must use powerful telescopes to see what's inside the atmospheres of exoplanets.

A possible indication of life, or biosignature, could be a combination of gases like oxygen and methane in the atmosphere. Similarly, a sign of technology on an exoplanet, called a technosignature, could be what's considered pollution here on Earth—the presence of a gas that's released as a byproduct of a widespread industrial process, such as NO₂.

This study is the first time NO₂ has been examined as a possible technosignature.

Other studies have examined chlorofluorocarbons (CFCs) as possible technosignatures, which are industrial products that were widely used as refrigerants until they were phased out because of their role in ozone depletion.

CFCs are also a powerful greenhouse gas that could be used to terraform a planet like Mars by providing additional warming from the atmosphere. As far as we know, CFCs are not produced by biology at all, so they are a more obvious technosignature than NO₂. However, CFCs are very specific manufactured chemicals that might not be prevalent elsewhere; NO₂, by comparison, is a general byproduct of any combustion process.

Atmospheric NO2 strongly absorbs some colors (wavelengths) of visible light, which can be detected by observing the light reflected from an exoplanet as it orbits its star. They found that for an Earth-like planet orbiting a Sun-like star, a civilization producing the same amount of NO₂ as ours could be detected up to about 30 light-years away with about 400 hours of observing time using a future large NASA telescope observing at visible wavelengths.

Nitrogen Dioxide Pollution as a Signature of Extraterrestrial Technology. arXiv:2102.05027v1 [astro-ph.EP] arxiv.org/abs/2102.05027

https://phys.org/news/2021-02-extraterrestrial-civilization-polluti...

Comment by Dr. Krishna Kumari Challa on February 11, 2021 at 11:16am

Centipedes shown to have incorporated the weapons of bacteria and fungi into their venoms

As part of an ongoing, wider study into centipede venoms,  researchers set out to discover whether centipede venom toxins may have evolved elsewhere in the tree of life, in places other than their direct, arthropod ancestors.

They soon unveiled that centipedes have repeatedly stocked their venoms with proteins that independently evolved within bacteria and fungi. The centipedes have acquired these toxin components through a process known as 'horizontal gene transfer'.

Horizontal gene transfer is a process by which genetic material moves between distantly related organisms, in this case between bacteria and fungi, and centipedes. It is distinguished from the movement of genetic material from parents to offspring and from ancestors to direct descendants, which is known as vertical gene transfer.

This finding  reveals the largest, most diversely sourced contribution of horizontal gene transfer to the evolution of animal venom composition known to date.'

Three of the five venom protein families that centipedes have acquired by horizontal gene transfer are used by bacteria explicitly to exploit their hosts', including by damaging their cells by the formation of pores. 

Researchers also noticed "three protein families were each horizontally transferred twice which shows that horizontal gene transfer is an unexpectedly important factor in the evolution of centipede venoms." While the mechanisms behind horizontal gene transfer, especially from bacteria to animals, are not well understood, it is known to have contributed a range of adaptive benefits to different groups of animals.

https://natureecoevocommunity.nature.com/posts/phylogenetic-analyse...

https://www.nhm.ac.uk/press-office/press-releases/centipedes-shown-...

https://researchnews.cc/news/5071/Centipedes-shown-to-have-incorpor...

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