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Some virus RNA can be reverse transcribed and inserted into the human genome, finds a new study, which may explain why some people who had already recovered from Covid-19 would sometimes inexplicably test positive on a PCR test weeks or even months later. Researchers from the Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology (MIT) in the US, showed that genetic sequences from the RNA virus SARS-CoV-2 can integrate into the genome of the host cell through a process called reverse transcription.
These sections of the genome can then be “read” into RNAs, which could potentially be picked up by a PCR test. The results are published online 6 in the journal Proceedings of the National Academy of Sciences. SARS-CoV-2 is not the only virus that integrates into the human genome. Around 8 percent of our DNA consists of the remnants of ancient viruses. Some viruses, called retroviruses, rely on integration into human DNA in order to replicate themselves.
“SARS-CoV-2 is not a retrovirus, which means it doesn’t need reverse transcription for its replication,” said first author Liguo Zhang, a postdoctoral researcher at Whitehead Institute. “However, non-retroviral RNA virus sequences have been detected in the genomes of many vertebrate species, including humans,” Zhang added. With this in mind, the team analyzed published datasets of RNA transcripts from different types of samples, including Covid-19 patient samples, to test whether this viral integration could be happening with the novel coronavirus.
They were able to calculate the fraction of genes that were transcribed in these patients’ cells which contained viral sequences that could be derived from integrated viral copies. The percentage varied from sample to sample, but for some, a relatively large fraction of viral transcripts seem to have been transcribed from viral genetic material integrated into the genome. For SARS-CoV-2, the frequency of integration in humans is still unknown. “The fraction of cells which integrate could be very small,” said Rudolf Jaenisch, professor of biology at MIT. “But even if it’s rare, there are more than 140 million people who have been infected already, right?”Jaenisch said. (IANS/JC)
The US researchers have discovered a class of immune cells that plays a role in miscarriage, which affects about a quarter of pregnancies.
Researchers at the University of California-San Francisco found that the recently discovered subset of cells known as extrathymic Aire-expressing cells in the immune system may prevent the mother's immune system from attacking the placenta and fetus.
The researchers showed that pregnant mice who did not have this subset of cells were twice as likely to miscarry, and in many of these pregnancies fetal growth was severely restricted.
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"When you're pregnant, the immune system is seeing the placenta for the first time in decades -- not since the mother made a placenta when she herself was a fetus," said Eva Gillis-Buck, from UCSF.
"Our research suggests that this subset of immune cells is carrying out a sort of 'secondary education' -- sometimes many years after the better-known population of the educator cells have carried out the primary education in the thymus -- teaching T cells not to attack the fetus, the placenta and other tissues involved in pregnancy," she added. The findings are published in the journal Science Immunology.
The immune system has to be educated not to attack one's own tissues and organs to prevent autoimmune disease. But pregnancy presents a unique challenge since the fetus expresses proteins found in the placenta as well as proteins whose genetics are distinct from the mother.
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"It was a conceptual leap to link Aire-expressing cells, which are critical for preventing autoimmune disease, to pregnancy," said Tippi Mackenzie, Professor of Surgery at UCSF's Center for Maternal Foetal Precision Medicine.
In the thymus, Aire-expressing cells begin interacting with other immune cells very early in life to teach them what not to attack. The thymus begins to shrink and is nearly gone by adulthood, by which time most immune cells have been educated. But as the thymus shrinks, the population of eTACs in lymph nodes and the spleen expands, the researchers explained.
The study suggests a healthy pregnancy may depend on having these cells around, they added. (IANS/KB)
The tiny emojis being shared on billions of devices worldwide can play a major role in digital communication, with most people saying that emoji compels them to feel more empathy towards others, according to an Adobe report.
Adobe's global emoji study found that emoji even helps people overcome language barriers and form connections that would otherwise be difficult to do.
"We were surprised and delighted by the discoveries made in the survey, most notably how enthusiastic respondents were for emoji as a means to express themselves," the company said in a statement.
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Emojis sometimes get criticized for being overly saccharine, but this sweetness is key when it comes to diffusing some of the heaviness of online communication.
"Many of the emoji are focused on positive emotions, so it's easy to insert them into our conversations and lighten the mood," the Adobe study said.
It's not surprising that over half of those surveyed feel more comfortable using emojis than talking on the phone or in person.
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This applies to less intense situations too. Dating, for example, can be tricky — especially when it's online or via digital apps, as it often is now.
The study also found that emoji even helps people overcome language barriers and form connections that would otherwise be difficult to do.
In celebration of World Emoji Day on Saturday, Adobe's '2021 Global Emoji Trend Report' surveyed 7,000 people in the US, the UK, Germany, France, Japan, Australia, and South Korea. (IANS/KB)
Following the grand Richard Branson show where he carried Andhra Pradesh-born Sirisha Bandla and fellow space travelers on his shoulders after successfully flying to the edge of space, it is time for Amazon Founder Jeff Bezos to applaud Sanjal Gavande, one of the key engineers who designed the New Shephard rocket set to take Bezos and the crew to space on July 20.
Billionaire Bezos is set to fly to the edge of space aboard what is touted as the world's first unpiloted suborbital flight. Born in Kalyan, Maharashtra, Gavande is a systems engineer at Blue Origin who always dreamt of designing aerospace rockets.
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After completing Bachelor's in mechanical engineering from the University of Mumbai, she flew to the US in 2011 to pursue a Master's in mechanical engineering from the Michigan Technological University. She also applied for an engineering job at the US space agency NASA but finally landed her dream job at Blue Origin
Sirisha flew to the US in 2011 to pursue a Master's in mechanical engineering from the Michigan Technological University.IANS
Bezos, his brother Mark, aviation pioneer Mary Wallace 'Wally' Funk, and other passengers are set to liftoff from west Texas and travel just beyond the edge of space on July 20. Blue Origin announced this week that Oliver Daemen, an 18-year-old high school graduate from the Netherlands, would join the crew.
Oliver is the son of millionaire Joe Daemen, Founder, and CEO of the Dutch investment company Somerset Capital Partners. Blue Origin, however, did not reveal how much Daemen paid for his son's trip to space. Bezos chose July 20 as the launch date to honor the 52nd anniversary of the Apollo 11 moon landing.
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The launch site for Blue Origin's first human flight will be in a remote location north of Van Horn, Texas, from where the firm had launched New Shepard for previous flights. Blue Origin has received final approval from the Federal Aviation Administration (FAA) to carry humans on the New Shepard rocket into space.
On July 12, Bandla touched the edge of space with three others, including Virgin Galactic's billionaire CEO Richard Branson. Bandla vaulted into space onboard VSS Unity 22. After the successful spaceflight, Branson carried the Indian-American on his shoulders while celebrating their flight to space, at Spaceport America in New Mexico. (IANS/KB)