Faced with a threat, the brain has to act fast, its neurons making new connections to learn what might spell the difference between life and death. But in its response, the brain also raises the stakes: As an unsettling recent discovery shows, to express learning and memory genes more quickly, brain cells snap their DNA into pieces at many key points, and then rebuild their fractured genome later.
The finding doesn’t just provide insights into the nature of the brain’s plasticity. It also demonstrates that DNA breakage may be a routine and important part of normal cellular processes—which has implications for how scientists think about aging and disease, and how they approach genomic events they’ve typically written off as merely bad luck.
The discovery is all the more surprising because DNA double-strand breaks, in which both rails of the helical ladder get cut at the same position along the genome, are a particularly dangerous kind of genetic damage associated with cancer, neurodegeneration and aging. It’s more difficult for cells to repair double-strand breaks than other kinds of DNA damage because there isn’t an intact “template” left to guide the reattachment of the strands.
Yet it’s also long been recognized that DNA breakage sometimes plays a constructive role, too. When cells are dividing, double-strand breaks allow for the normal process of genetic recombination between chromosomes. In the developing immune system, they enable pieces of DNA to recombine and generate a diverse repertoire of antibodies. Double-strand breaks have also been implicated in neuronal development and in helping turn certain genes on. Still, those functions have seemed like exceptions to the rule that double-strand breaks are accidental and unwelcome.
But a turning point came in 2015. Li-Huei Tsai, a neuroscientist and director of the Picower Institute for Learning and Memory at the Massachusetts Institute of Technology, and her colleagues were following up on previous work that had linked Alzheimer’s disease with the accumulation of double-strand breaks in neurons. To their surprise, the researchers found that stimulating cultured neurons triggered double-strand breaks in their DNA, and the breaks quickly increased the expression of a dozen fast-acting genes associated with synaptic activity in learning and memory.
The double-strand breaks seemed to be essential for regulating gene activity important to the neurons’ function. Tsai and her collaborators hypothesized that the breaks essentially released enzymes that were stuck along twisted pieces of DNA, freeing them to transcribe relevant nearby genes quickly. But the idea “was met with a lot of skepticism,” Tsai said. “People simply have a hard time imagining that double-strand breaks can actually be physiologically important.”
Nevertheless, Paul Marshall, a postdoctoral researcher at the University of Queensland in Australia, and his colleagues decided to follow up on the finding. Their work, which appeared in 2019, both confirmed and extended the observations by Tsai’s team. It showed that the DNA breakage touched off two waves of enhanced gene transcription, one immediate and one several hours later.
Marshall and his colleagues proposed a two-step mechanism to explain the phenomenon: When the DNA breaks, some enzyme molecules are freed for transcription (as Tsai’s group suggested) and the site of the break is also chemically flagged with a methyl group, a so-called epigenetic marker. Later, when repair of the broken DNA begins, the marker is removed—and in the process, still more enzymes can spill free, starting the second round of transcription.
“Not only is the double-strand break involved as a trigger,” Marshall said, “it then becomes a marker, and that marker itself is functional in terms of regulating and guiding machinery to that location.”
Since then, other studies have demonstrated something similar. One, published last year, associated double-strand breaks not just with the formation of a fear memory, but with its recollection.
Now, in a study last month in PLOS ONE, Tsai and her colleagues have shown that this counterintuitive mechanism of gene expression might be prevalent in the brain. This time, instead of using cultured neurons, they looked at cells in the brains of living mice that were learning to associate an environment with an electric shock. When the team mapped genes undergoing double-strand breaks in the prefrontal cortex and hippocampus of mice that had been shocked, they found breaks occurring near hundreds of genes, many of which were involved in synaptic processes related to memory.
23,000-year-old human footprints found in White Sands – Sunday Vision
Alamogordo- New scientific research conducted in New Mexico’s White Sands National Park – located 73 miles, 117.5 kilometers, northeast of El Paso – has revealed the oldest known human footprints in North America.
This discovery reveals evidence of humans having been in North America – specifically in the Tularosa Basin – at least 23,000 years ago, thousands of years earlier than previously thought.
The relics were found at the bottom of a dry lake in White Sands National Park, and were first seen in 2009 by a park administrator. Scientists from the US Geological Survey analyzed the seeds attached to the footprints to determine their approximate age, which ranges from 22,800 to 21,130 years.
Most scholars believe that the ancient migration occurred via a now submerged land bridge linking Asia to Alaska.
Based on various types of evidence — such as stone tools, fossil bones, and genetic analysis — other researchers have offered a range of possible dates that put humans on the American continent between 13,000 and 26,000 years ago or more.
The authors add that the current study provides a stronger basis for when humans were certainly in North America, although they could have arrived earlier.
Superintendent Mary Sutter said: “These amazing discoveries demonstrate that White Sands National Park is not only a world-class destination for recreation, it is also an outstanding scientific laboratory that has produced ground-breaking research.”
Fossilized human footprints were buried in multiple layers of sediment on a large beach in White Sands National Park. The seeds embedded in the footprints were radiocarbon dated and analyzed by the United States Geological Survey (USGS) to determine their age. The research significantly expands the coexistence of humans and the Pleistocene (Ice Age) megafauna and confirms that humans were present in North America before the great advance of glaciers at the height of the last Ice Age that closed migration routes from Asia. The results are detailed in an article published in the journal Science.
The researchers wrote that the fossilized footprints are indisputable evidence and stronger than “cultural artifacts, modified bones, or other traditional fossils.”
“What we are presenting here is evidence of a specific time and place,” they said.
Based on the size of the footprints, researchers believe that at least some of them were left by children and teenagers who lived during the last Ice Age.
“This study demonstrates the scientific process: New evidence can change long-term models,” said Alison Shipp, acting regional director at USGS Rocky Mountain.
White Sands National Park contains the world’s largest collection of fossilized footprints from the Ice Age (Ice Age) and has been recognized as a mega-site since 2014. In addition to human footprints, the footprints of the Colombian mammoth, saber, dire wolf and other animals of the era icy;
Scientists from White Sands National Park, the National Park Service, the USGS, Bournemouth University, the University of Arizona, and Cornell University, collaborated with and consulted on the park’s Native American partners on this research.
White Sands National Park protects and preserves the world’s largest sand dune field, at least 23,000 years of adaptable archeology, flora and fauna, as well as historic buildings, with architecture that mimics those of the indigenous peoples, built during the Works Progress Administration era, Between 1939 and 1943.
Previous excavations in White Sands National Park have revealed fossilized footprints of a saber-toothed tiger, giant wolf, Columbian mammoth, and other Ice Age animals.
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Where does outer space begin? – The Clare People – The Clare People
Since then, it has continued to expand more and more, an expansion that lasts 11, 8 billion years. This means that you, me, the Earth, the Sun and the Milky Way are just in a space that already existed at the Big Bang, but that has expanded enough to fit all these cosmic objects that enchant us during a night clear of clouds and fog. This is why we cannot point to the direction where the Big Bang occurred. In a way, we are at the place where it happened.
It is also for these same reasons that the cosmic background radiation (the “fossil” of light left over from the Big Bang) is observed in any direction in space where we look—with large telescopes, of course. Thus, the most appropriate way to ask about the beginning of the universe is not “where” but “when”. This is also true for “where does space outside Earth begin?”, because the Earth is immersed in this space, which is the very expansion that resulted from the Big Bang.
The space where our little one The pale “dot” we call a planet already existed in the Big Bang. It makes no sense to ask where it starts, because we have no external reference to the cosmos. We are in the same universe, where the space between galaxies increases, and where energy and matter are changing all the time.
Where is the edge of the Earth’s atmosphere?
Well, if your question is where the domains of the Earth’s atmosphere end, perhaps the answer could be more objective — but it isn’t! The boundary between our atmosphere and outer space (from the English “outer space”, which literally means “outer space”) is also quite relative. It was not enough to know that the “external space” is nothing else where we are immersed, there is also no exact definition for this border.
There are some international treaties that define “space” as something free for exploration and use by all (as long as it is not used for military purposes), but this does not apply to sovereign airspace above nations, for example. Therefore, countries define their own limits and the laws that govern airspace and outer space are different. So where does a country’s airspace end and space begin? This is a political issue, and some countries, like the US, have resisted the idea of delimiting borders.
It is also difficult to define these limits through the atmosphere, because it doesn’t end up “out of nowhere” , but gradually diminishes until it becomes a thin layer in space. If we take this definition literally, many satellites, and the International Space Station itself, would still be on Earth rather than in space. But things are more complicated than that.
Some experts might also say that space starts at the point where the atmosphere alone is not enough to support a spaceship at suborbital speeds. The opposite may also be true — there must be a limit where satellites can no longer orbit. If we observe the flight of all satellites with publicly available data, we realize that they can orbit the planet countless times below an altitude of approximately 80 km, but those who dipped below 100 km met a quick and fulminating end, most of the time.
I was once a child with a dream looking up to the stars. Now I’m an adult in a spaceship looking down to our beautiful Earth. To the next generation of dreamers: if we can do this, just imagine what you can do https://t.co/Wyzj0nOBgX #Unity13 @virgingalactic pic.twitter.com/03EJmKiH8V
— Richard Branson (@richardbranson) July 11, 470533
Apparently there are few atmospheric effects above 13 km of altitude. But maybe there is not much interest from companies, organizations and countries in establishing this limit. On the other hand, as space tourism becomes more and more real, the debate may be amplified. After all, if you pay a fortune to go into space, you’ll probably want to make sure you’re actually off planet Earth. a lot of confidence that our planet’s boundary with “outer space” is this or that altitude.
Source: National Geographic, Astronomy
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Elon Musk ridicules President Biden after SpaceX completes its first all-civil mission – Texasnewstoday.com
After SpaceX completed its historic private spaceflight on Saturday, CEO Elon Musk took a potshot with President Joe Biden, who has not yet mentioned the performance of the company and private flight crew.
“The U.S. president admits four latest American astronauts who helped raise hundreds of millions of dollars for St. Jude,” said one of Musk’s 60 million followers on Twitter, a social networking platform. I even refused. What is your theory of why? What? “
Musk replied, “He is still asleep.”
As CNBC previously reported, SpaceX returned the Crew Dragon spacecraft from orbit safely yesterday. After spending three days in space, Capsule carried four members of the Inspiration 4 mission to Earth.
One of the main goals of the Inspiration4 mission was to raise $ 200 million for the St. Jude Children’s Research Hospital. Raised $ 160.2 million by Saturday. After Inspiration4 splashed down, Musk personally promised to donate $ 50 million, boosting the total campaign to $ 210 million.
The White House and SpaceX did not immediately respond to requests for comment.
NASA’s top executives congratulated Mask and SpaceX on the Inspiration 4 mission. SpaceX’s competitors have acknowledged that, with praise from Boeing, Lockheed Martin, Blue Origin, and fellow Mask rivals Jeff Bezos shared on social media.
This marked the first private SpaceX space flight by a non-professional crew. In addition, the mission included the first black woman to pilot a spacecraft, the youngest American to ever become an astronaut, and the first to fly in space with a prosthetic limb. rice field.
Musk recently said he “wants to get away from politics,” but his quibble on Sunday showed his willingness to pierce the Democratic president and repeat right-wing taunts about Biden.
During the 2020 campaign, former President Donald Trump frequently insulted then-candidate Biden by calling him “Sleepy Joe.”
More recently, Trump sent Biden’s ironic wishes prior to the June summit meeting with Russian President Vladimir Putin. “Good luck to Biden in dealing with President Putin. Don’t sleep during the meeting. I give my heartfelt respect to him,” he said in an email statement at the time.
SpaceX usually enjoys a good relationship with the federal government. For example, it won a $ 2.89 billion contract to build NASA’s next crew member’s lunar lander, beating Jeff Bezos’ Blue Origin and Leidos’ subsidiary Dynetics. SpaceX has sent 10 astronauts to the ISS so far.
However, SpaceX is under investigation by the Justice Department after being accused of discriminating against job seekers based on citizenship status. This is an investigation that began during the Trump administration.
In addition to his responsibilities at SpaceX, Musk is also the CEO of electric car maker Tesla. (Tesla is also a SpaceX supplier.)
In that position, he recently lamented the Biden administration’s proposal to allocate an additional $ 4,500 incentive to certain new small electric passenger car buyers. One provision of the proposal is that electric vehicles should be domestically made by the union.
The company operates a battery plant in Nevada, an auto assembly plant in California, and is building another plant outside Austin, Texas, but Tesla is the only major unintegrated production here. American car maker.
“This was written by a Ford / UAW lobbyist while manufacturing an electric car in Mexico. It’s not clear how this will help American taxpayers,” Musk said on Twitter on September 12. No, “he said.
In Cars.com’s 2021 annual American Made Index, Tesla’s popular Model 3 electric sedan outperformed its crossover model Y in third place.
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