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Astronomers Just Found an Extremely Rare 'Ring of Fire' Galaxy in The Early Universe - ScienceAlert
In the early days of the Universe, 10.8 billion years ago, astronomers have just found a galaxy wearing the battlescars of a cosmic brawl. It's not a blob or disc of stars, like most galaxies, but a giant doughnut - with a huge hole punched right thr
In the early days of the Universe, 10.8 billion years ago, astronomers have just found a galaxy wearing the battlescars of a cosmic brawl. It's not a blob or disc of stars, like most galaxies, but a giant doughnut - with a huge hole punched right through its centre. This classifies it as a rare type of galaxy known as a ring galaxy, and it's rare even among that type - its shape forged not by internal processes, but a collision that saw its core stripped away as the other galaxy passed through. The galaxy is called R5519, and it's the first collisional ring galaxy ever found more than a few hundred light-years away - which makes it the only known such object in the early Universe. "It is a very curious object that we've never seen before," said astronomer Tiantian Yuan of the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) in Australia. "It looks strange and familiar at the same time." The outer edge of R5519's ring is pretty large, around 42,400 light-years across (on average). The hole punched through the middle is about 17,612 light-years across, with no detectable trace of the star-packed bulge that normally fills a galactic centre. And there are clues that hint at a violent past. Some ring galaxies seem to have had relatively peaceful formations, produced by such processes as orbital resonance or the accretion of material from another nearby galaxy. But the former usually occurs in barred galaxies, and no such bar was observed in R5519; the accretion process shouldn't disrupt the core, as seen in galaxies such as NGC 7742 and Hoag's Object. In addition, R5519 exhibits a high rate of star formation in its ring - around 80 solar masses' worth of new stars are born every year. This is suggestive of a gravitational disruption - by, say, another galaxy punching through R5519, sending density waves propagating radially outwards. As these waves push and condense the gas and dust in the galaxy, it triggers star formation by facilitating the gravitational collapse of clumps of dust that turn into baby stars. (James Josephides/Swinburne Astronomy Productions) In the local Universe, ring galaxies of this type are extremely rare - 1,000 times rarer than ring galaxies formed by less violent processes. The discovery of R5519 suggests, the researchers said, that collisional ring galaxies were as rare in the early Universe as they are in later times. But it also offers an opportunity to study the formation of disc galaxies like the Milky Way - because in order to form a ring, simulations suggest the galaxy needed to be a thin disc before being punched through. We didn't think thin disc galaxies formed in the early Universe - most of the galaxies we've found are disordered hot messes, with blobby shapes and stars orbiting in all directions. Nice, orderly discs don't start appearing until around 4 to 6 billion years after the Big Bang, which took place around 13.8 billion years ago. Last week, astronomers revealed they'd identified a disc galaxy 12.5 billion light-years away, which was pretty mind-blowing. Now the discovery of R5519 10.8 billion light-years away seems to support the idea that discs weren't that rare in the early Universe after all. "The thin disc is the defining component of spiral galaxies: before it assembled, the galaxies were in a disorderly state, not yet recognisable as spiral galaxies," said astronomer Kenneth Freeman of the Australian National University in Australia. "In the case of this ring galaxy, we are looking back into the early Universe by 11 billion years, into a time when thin disks were only just assembling. For comparison, the thin disc of our Milky Way began to come together only about 9 billion years ago. This discovery is an indication that disc assembly in spiral galaxies occurred over a more extended period than previously thought." The research has been published in Nature Astronomy.
Bumblebees Bite Plants to Make Them Bloom, Scientists Find - ScienceAlert
When you wake up hungry and there's nothing to eat, the most sensible thing to do is acquire snacks. In this, bumblebees are no different from humans. If they wake early from hibernation to find a scarcity of pollen, the insects have a cunning way to
When you wake up hungry and there's nothing to eat, the most sensible thing to do is acquire snacks. In this, bumblebees are no different from humans. If they wake early from hibernation to find a scarcity of pollen, the insects have a cunning way to force plants to flower. Using their mandibles and proboscises, bumblebees (Bombus terrestris) chew holes in plant leaves, causing them to bloom weeks earlier than they usually would, in turn supplying the bees with food. It could be providing the fuzzy little insects with a valuable survival tool when warmer temperatures due to climate change wake them from hibernation early - that is, before plants usually start flowering. Researchers at ETH Zürich first noticed the peculiar behaviour in a greenhouse they had set up to study how bees respond to plant smells, Science Magazine reported. "Initial behavioural observations with four plant species revealed that bumblebee workers use their proboscises and mandibles to cut distinctively shaped holes in plant leaves, with each damage event taking only a few seconds," the researchers wrote in their paper. "However, we saw no clear evidence that bees were actively feeding on leaves or transporting leaf material back to the hive." Previous research had found that abiotically inducing stress in plants could accelerate the flowering timeline. So, the researchers hypothesised that if the bees were not eating the leaves or using them for nests, perhaps the plant-munching was for another reason - using this plant stress response to get aboard the pollen train sooner. To test this idea, the team put mesh cages over black mustard (Brassica nigra) and tomato plants (Solanum lycopersicum) that weren't due to flower, and released hungry, pollen-deprived bumblebees inside. As a control, more plants of each kind were set up in a greenhouse without bumblebees; in another group of each plant, the researchers themselves cut holes in the leaves in the same-half-moon shapes they'd seen the bumblebees cut. Then, they watched and waited. (Pashalidou et al., Science, 2020) The results were jaw-dropping. Black mustard plants chewed by bumblebees flowered on average 16 days earlier than the unchewed controls. The tomato plants were even more striking - they flowered up to 30 days earlier. The team also found that bumblebees deprived of pollen conducted significantly more damage to non-flowering plants than the bees with sufficient food, suggesting that hunger drives the rate at which bumblebees damage plants. They even saw two other species of bumblebee - the red-tailed bumblebee (B. lapidarius) and white-tailed bumblebee (B. lucorum) damaging plants in the same manner, confirming that the behaviour is not exclusive to commercial bumblebee hives. Where it gets really interesting though, is when it comes to the plants the researchers cut up to mimic bumblebee damage. They flowered earlier than the undamaged controls, but not nearly as early as the plants chewed by bees. The human-damaged mustard plants only flowered eight days earlier, and the tomato plants just five. Why this is the case is not yet known. It's possible that the bees release a chemical that triggers a stronger response in the plants, but more research will be needed to figure this out for sure. The results do suggest that bumblebees have access to an adaptive survival tool that could prove vital as the climate continues to warm. It's possible that the plants have adapted to respond to this bee-haviour, too - if the bumblebees die from lack of food, pollination could be greatly reduced, so it benefits the plants to flower when their pollinators need them to. In turn, this could mean these organisms are just a little bit more resistant to a changing climate than we thought, which is encouraging in the face of the growing climate crisis. "The demonstration that bee-inflicted leaf damage can have strong effects on time to flowering may have important ecological implications, including for the resilience of plant-pollinator interactions to increases in phenological asymmetry caused by anthropogenic environmental changes," the researchers wrote. The research has been published in Science.
Pangolins May Not Have Been The Intermediary Host of SARS-CoV-2 After All - ScienceAlert
Understanding the origins of the virus causing COVID-19 is one of the key questions scientists are trying to resolve while working out how to manage the pandemic. But in a fast-evolving situation, we're bound to point our fingers at a few innocent su
Understanding the origins of the virus causing COVID-19 is one of the key questions scientists are trying to resolve while working out how to manage the pandemic. But in a fast-evolving situation, we're bound to point our fingers at a few innocent suspects along the way. The current hypothesis goes something like this: SARS-CoV-2 passed through a mystery animal host in its suspected evolutionary journey from bats to humans. Critically endangered pangolins have been a favoured candidate for this intermediary host, but now a genomic analysis led by geneticist Ping Liu from Guangdong Academy of Science in China has provided evidence this may not be the case. SARS-CoV-2 belongs to the Betacoronavirus genus of coronaviruses; this group of coronaviruses primarily infects mammals, and the new study suggests that pangolins are indeed natural hosts for them. The team pieced together almost an entire genome of the coronaviruses found in two sick Malayan pangolins (Manis javanica). They called the coronavirus isolated from these critically endangered animals pangolin-CoV-2020. Its final sequence had 29,521 base pairs, only slightly shorter than the 30,000-odd base pairs making up SARS-CoV-2. The resulting genome displayed a 90.32 percent sequence similarity to SARS-CoV-2 and 90.24 percent to the Rhinolophus affinis bat coronavirus BatCoV-RaTG13, which still remains the closest known relative to SARS-CoV-2, with a match of 96.18 percent. But the sequence similarities don't reflect the full story. The genetic instructions for the all-important protein spike of the SARS-CoV-2 virus matched more between the bat and human coronavirus than the pangolin one. However, the pangolin virus essentially shares the same ACE2 binding receptor as that used by the COVID-19 virus - the part of the spike that allows the virus to enter and infect human cells. This was also found in another study that is still undergoing review, and led to suggestions that the human coronavirus may be a type of hybrid (a chimera) between a bat and a pangolin virus. Liu's team also thinks these similarities may indicate that a recombination event occurred somewhere in the evolution of these different viruses - where the viral genomes exchanged pieces of their genetic materials with each other. However, their analysis of the evolutionary relationship between the three viruses did not support the idea that the human version evolved directly from the pangolin one. "At the genomic level, SARS-CoV-2 was also genetically closer to Bat-CoV-RaTG13 than pangolin-CoV-2020," they wrote in their paper. There are clearly still a lot of unknowns. With well over 4 million confirmed cases around the world, and a death toll still increasing sharply, the need to understand as much as we can about this virus just continues to intensify. However, one thing all these genetics studies have firmly ruled out is the idea that the virus was lab made. As for the pangolins, they had been rescued by the Guangdong Wildlife Rescue Center after being smuggled for black market trade, and sadly succumbed to their illness. Liu's team could not determine if their deaths were linked to the coronavirus they found. But perhaps a little good can arise from all this, at least for the world's most trafficked mammal, with the researchers concluding: "Minimising the exposures of humans to wildlife will be important to reduce the spillover risks of coronaviruses from wild animals to humans." The new research was published in PLOS Pathogens.