Science News

‘The End of Everything’ explores the ways the universe could perish

Tue, 04 Aug 2020 13:47:38 GMT

The End of Everything
Katie Mack
Scribner, $26

Eventually, the universe will end. And it won’t be pretty.

The universe is expanding at an accelerating clip, and that evolution, physicists expect, will lead the cosmos to a conclusion. Scientists don’t know quite what that end will look like, but they have plenty of ideas. In The End of Everything, theoretical astrophysicist Katie Mack provides a tour of the admittedly bleak possibilities. But far from being depressing, Mack’s account mixes a sense of reverence for the wonders of physics with an irreverent sense of humor and a disarming dose of candor.

Some potential finales are violent: If the universe’s expansion were to reverse, the cosmos collapsing inward in a Big Crunch, extremely energetic swells of radiation would ignite the surfaces of stars, exploding them. Another version of the end is quieter but no less terrifying: The universe’s expansion could continue forever. That end, Mack writes, “like immortality, only sounds good until you really think about it.” Endless expansion would beget a state known as “heat death” — a barren universe that has reached a uniform temperature throughout (SN: 10/2/09). Stars will have burned out, and black holes will have evaporated until no organized structures exist. Nothing meaningful will happen anymore because energy can no longer flow from one place to another. In such a universe, time ceases to have meaning.

Perhaps more merciful than the purgatory of heat death is the possibility of a Big Rip, in which the universe’s expansion accelerates faster and faster, until stars and planets are torn apart, molecules are shredded and the very fabric of space is ripped apart.

These potential endings are all many billions of years into the future — or perhaps much further off. But there’s also the possibility that the universe could end abruptly at any moment. That demise would not be a result of expansion or contraction, but due to a phenomenon called vacuum decay. If the universe turns out to be fundamentally unstable, a tiny bubble of the cosmos could convert to a more stable state. Then, the edge of that bubble would expand across the cosmos at the speed of light, obliterating anything in its path with no warning. In a passage a bit reminiscent of a Kurt Vonnegut story, Mack writes, “Maybe it’s for the best that you don’t see it coming.”

Already known for her engaging Twitter personality, public lectures and popular science writing, Mack has well-honed scientific communication chops. Her evocative writing about some of the most violent processes in the universe, mixed with her obvious glee at the unfathomable grandness of it all, should both satisfy longtime physics fans and inspire younger generations of physicists.

Reading Mack’s prose feels like learning physics from a brilliant, quirky friend. The book is sprinkled with plenty of informal quips: “I’m not going to sugarcoat this. The universe is frickin’ weird.” Readers will find themselves good-naturedly rolling their eyes at some of the goofy footnotes and nerdy pop-culture references. At the same time, the book delves deep into gritty physics details, thoroughly explaining important concepts like the cosmic microwave background — the oldest light in the universe — and tackling esoteric topics in theoretical physics. Throughout, Mack does an excellent job of recognizing where points of confusion might trip up a reader and offers clarity instead.

Mack continues a long-standing tradition of playfulness among physicists. That’s how we got stuck with somewhat cheesy names for certain fundamental particles, such as “charm” and “strange” quarks, for example. But she also brings an emotional openness that is uncommon among scientists. Sometimes this is conveyed by declarations in all caps about how amazing the universe is. But other times, it comes when Mack makes herself vulnerable by leveling with the reader about how unnerving this topic is: “I’m trying not to get hung up on it … the end of this great experiment of existence. It’s the journey, I repeat to myself. It’s the journey.”

Yes, this is a dark subject. Yes, the universe will end, and everything that has ever happened, from the tiniest of human kindnesses to the grandest of cosmic explosions, will one day be erased from the record. Mack struggles with what the inevitable demise of everything means for humankind. By contemplating the end times, we can refine our understanding of the universe, but we can’t change its fate.

Buy The End of Everything from Amazon.com. Science News is a participant in the Amazon Services LLC Associates Program. Please see our FAQ for more details.

Wild bees add about $1.5 billion to yields for just six U.S. crops

Tue, 04 Aug 2020 10:00:00 GMT

U.S. cherries, watermelons and some other summertime favorites may depend on wild bees more than previously thought.

Many farms in the United States use managed honeybees to pollinate crops and increase yields, sometimes trucking beehives from farm to farm. Now an analysis of seven crops across North America shows that wild bees can play a role in crop pollination too, even on conventional farms abuzz with managed honeybees. Wild volunteers add at least $1.5 billion in total to yields for six of the crops, a new study estimates.

“To me, the big surprise was that we found so many wild bees even in intense production areas where much of the produce in the USA is grown,” says coauthor Rachael Winfree, a pollination ecologist at Rutgers University in New Brunswick, N.J.

That means threats to wild bees could shave profits even when farms stock honeybees, the researchers report July 29 in Proceedings of the Royal Society B. Both honeybees (Apis mellifera), which aren’t native to the United States, and wild pollinators such as bumblebees (Bombus spp.) face dangers including pesticides and pathogens (SN: 1/22/20).

To see what, if anything, wild native bee species contribute, researchers spot-checked bee visits to flowers at 131 commercial farm fields across the United States and part of Canada. In a novel twist, the researchers also calculated to what extent the number of bee visits limited yields.

These intensive farms with plenty of fertilizer, water and other resources often showed signs of reaching a pollinator limit, meaning fields didn’t have enough honeybees to get the maximum yield, and volunteer wild bees were adding to the total. Then the team estimated what percentage of the yield native bees were adding — versus just doing what honeybees would have done anyway.

Wild bees don’t seem to help California’s almond orchards. But based on orchards in Michigan and Pennsylvania, some $1.06 billion of apples depends on native pollinators, the researchers say. Watermelons, particularly in Florida, get an estimated $146 million benefit, and sweet cherries $145 million. Native bees also boost tart cherries and blueberries and dominate pumpkins.

A submerged Inca offering hints at Lake Titicaca’s sacred role

Mon, 03 Aug 2020 23:01:00 GMT

A stone box fished out of Lake Titicaca contains tiny items that add an intriguing twist to what’s known about the Inca empire’s religious practices and supernatural beliefs about the massive lake.

Divers exploring an underwater portion of the lake’s K’akaya reef found a ritual offering deposited by the Inca, say archaeologists Christophe Delaere of the University of Oxford and José Capriles of Penn State. The carved stone container holds a miniature llama or alpaca carved from a spiny oyster shell and a gold sheet rolled into a cylinder about the length of a paperclip, the scientists report in the August Antiquity. The meaning of these objects to the Inca are unclear.

Researchers suspect the Inca placed these two items in this stone box and then used ropes to lower it into the water during a religious ceremony of some kind.T. Seguin/Univ. libre de Bruxelles

The location of the K’akaya offering indicates that Inca people regarded all of Lake Titicaca, which straddles the border between Bolivia and Peru, as sacred, not just its fabled Island of the Sun, the researchers say.

Spanish documents described the Inca, who had no writing system (SN: 6/11/19), as believing that their ancestors had originated on the Island of the Sun, about 30 kilometers south of K’akaya Island. Inca rulers, whose empire lasted from 1400 to 1532, built a ceremonial center there. And until now, it’s the only place on Lake Titicaca where similar submerged stone boxes bearing figurines and gold sheets have been found. Of at least 28 stone boxes found there since 1977, many had been looted; only four had partially preserved or intact contents.

Stone boxes containing figurines and gold items have also been uncovered at sites of Inca child sacrifices in the Andes. A connection may have existed between human sacrificial ceremonies that were intended to appease Inca deities and events held at Lake Titicaca, including the submerging of ritual offerings, the researchers suggest.

Water beetles can live on after being eaten and excreted by a frog

Mon, 03 Aug 2020 15:00:00 GMT

For most insects, the sticky, slingshot ride straight into a frog’s mouth spells the end. But not for one stubborn water beetle.

Instead of succumbing to the frog’s digestive juices, an eaten Regimbartia attenuata traverses the amphibian’s throat, swims through the stomach, slides along the intestines and climbs out the frog’s butt, alive and well.

“This is legitimately the first article in a while that made me say, ‘Huh! How weird!’” says Crystal Maier, an entomologist at Harvard University’s Museum of Comparative Zoology. “There are still a lot of truly bizarre habits of insects that still wait to be discovered,” she says.

Surviving digestion-by-predator is rare, but not unheard of in the animal kingdom. Some snails survive the trip through fish and birds by sealing their shells and waiting it out. But research published August 3 in Current Biology is the first to document prey actively escaping through the backside of a predator.

Feeding beetles to predators to see what happens is a regular activity for Shinji Sugiura, an ecologist at Kobe University in Japan. In 2018, he discovered that bombardier beetles can force toads to vomit the insects back up by releasing a mix of hot, noxious chemicals from their rear ends (SN: 2/6/18).

On a hunch that R. attenuata might have evolved its own interesting evasive behaviors, Sugiura paired a beetle with a frog that the insect often encounters while swimming through Japanese rice paddies. In his laboratory, he watched.

The frog made easy prey of the unsuspecting beetle. While the amphibians lack teeth that could kill prey with a crunch, a trip through the acidic, oxygen-poor digestive system should be sufficient to neutralize the insect. But as Sugiura monitored the frog, he saw the shiny black beetle slip out from the frog’s behind and scurry away, seemingly unharmed.

About two hours before this video begins, this pond frog (Pelophylax nigromaculatus) ate a water beetle (Regimbartia attenuata). After traversing the digestive tract, the beetle emerges from the back end of the amphibian, alive. It’s the first documented example of prey actively escaping a predator through the digestive system.

“I was very surprised,” he says. “I was expecting that the frogs might just spit out the beetles or something.”

After more than 30 additional beetle-frog pairings, Sugiura found that over 90 percent of beetles survived being eaten, greatly outshining other animals known to survive digestion-by-predator. Those creatures typically survive less than 20 percent of the time. On average, it took six hours for the beetles to escape, though one intrepid individual completed the journey in just six minutes.

Sugiura confirmed that the beetles were actively escaping from the frog’s digestive tract by using sticky wax to fix some beetles’ legs together. None of these immobilized beetles survived, and their carcasses took a day or longer to pass through the frogs.

R. attenuata’s aquatic lifestyle likely prepared the beetle to survive digestion, Sugiura says. Its streamlined, but sturdy, exoskeleton may shield the insect from digestive juices. And its ability to breath underwater via air pockets tucked under its hardened wings likely prevents suffocation.

Sugiura plans to test the limits of R. attenuata’s abilities by pairing the insect with larger frogs, toads and even fish. “I’m looking forward to finding unimaginable types of antipredator defense,” he says.

Some spiders may spin poisonous webs laced with neurotoxins

Mon, 03 Aug 2020 12:00:00 GMT

Orb weaver spiders are known for their big, beautiful webs. Now, researchers suggest that these webs do more than just glue a spider’s meal in place — they may also swiftly paralyze their catch.

Biochemical ecologist Mario Palma has long suspected that the webs of orb weavers — common garden spiders that build wheel-shaped webs — contain neurotoxins. “My colleagues told me, ‘You are nuts,’” says Palma, of São Paulo State University’s Institute of Biosciences in Rio Claro, Brazil. No one had found such toxins, and webs’ stickiness seemed more than sufficient for the purpose of ensnaring prey.

The idea first came to him about 25 years ago, when Palma lived near a rice plantation where orb weavers were common. He says he often saw fresh prey, like bees or flies, in the spiders’ webs, and over time, noticed the hapless animals weren’t just glued — they convulsed and stuck out their tongues, as if they’d been poisoned. If he pulled the insects free, they struggled to walk or hold up their bodies, even if the web’s owner hadn’t injected venom.

Palma had worked with neurotoxins for many years, and these odd behaviors immediately struck him as the effects of such toxins.

Now, thanks in large part to the work of his Ph.D. student Franciele Esteves, Palma thinks he has found those prey-paralyzing toxins. The pair and their colleagues analyzed the active genes and proteins in the silk glands of banana spiders (Trichonephila clavipes) — a kind of orb weaver — and found proteins resembling known neurotoxins. The neurotoxins may make the webs paralytic traps, the team reports online June 15 in the Journal of Proteome Research. The prey-catching webs of other species probably have similar neurotoxins, Palma says.

These neurotoxin proteins also showed up on the silk of webs collected in Rio Claro, packed into fatty bubbles in microscopic droplets on the strands. And when the researchers rinsed substances from webs and injected them into bees, the animals became paralyzed in less than a minute.

The researchers also confirmed, as Palma’s lab had reported in 2006, that fatty acids are present in the droplets. These acids, Palma thinks, are the toxins’ way into prey. The molecules may dissolve the insect’s waxy outer cuticle, the chief barrier to topical toxins.

“Toxic webs would certainly make sense,” says David Wilson, a venom researcher at James Cook University in Cairns, Australia, but he’d like to see evidence that the web toxins work quickly on contact. Alternatively, they might act as antimicrobials (SN: 10/30/19) or help deter ants and other animals that steal from webs or eat the spiders.

Jolanta Beinaroviča, a synthetic spider silk designer at the University of Nottingham in England, says, “This paper was like a breath of fresh air.” She thinks many researchers have long oversimplified spider web silks, though she, too, would like to see further demonstration of the toxins’ topical action.

Paralytic toxins may be just part of the underappreciated complexity of web design. Palma plans to have his students dive deeper into smaller, as of yet unidentified proteins his team found. He thinks they may help keep the prey alive until the spider’s ready for a fresh meal.

Heavy drinking drove hundreds of thousands of Americans to early graves

Mon, 03 Aug 2020 10:00:00 GMT

Heavy drinking is robbing Americans of decades of life.

From 2011 to 2015, an average of 93,296 deaths annually could be tied to excessive alcohol use, or 255 deaths per day. Excessive drinking brought death early, typically 29 years sooner than would have been expected.

All told, the United States saw 2.7 million years of potential life lost each year, researchers report in the July 31 Mortality and Morbidity Weekly Report.

The researchers used a program developed by the U.S. Centers for Disease Control and Prevention that estimates annual deaths and years of potential life lost due to an individual’s own or another’s excessive drinking. The tool takes into account whether the cause of death is fully attributable to alcohol, such as alcoholic liver cirrhosis, or whether excessive drinking can partially contribute to a condition, such as breast cancer.

Annually, about 51,000 of the deaths were from chronic conditions. The rest were sudden demises such as poisonings that involved another substance along with alcohol or alcohol-related car crashes.

The CDC defines excessive alcohol use as binging — drinking five or more drinks at a time for men, four or more for women — or drinking heavily over the course of the week. Men qualify at 15 or more drinks per week; for women, it’s eight or more.

The numbers of deaths and years of life extinguished due to excessive drinking have gone up since the last report. That assessment covered 2006 to 2010 and reported close to 88,000 deaths and 2.5 million lost years annually. Recommendations from the Community Preventive Services Task Force, made up of public health and prevention experts, to stem excessive drinking include raising taxes on alcohol and regulating the number of places that sell alcoholic beverages (SN: 8/9/17).

Hydroxychloroquine can’t stop COVID-19. It’s time to move on, scientists say

Sun, 02 Aug 2020 10:00:00 GMT

As a frontline doctor working with COVID-19 patients at Columbia University Medical Center in New York City, Neil Schluger had horrific days.

“I would come into the ward in the morning to make rounds and say to the intern, ‘How did we do last night?’ And the intern said, ‘Well, I had 10 COVID admissions, and three of them have already died.’ It was like nothing I’ve experienced in 35 years of being a physician,” Schluger says.

When he first heard about hydroxychloroquine, he hoped it would work for his patients. He and colleagues prescribed the antimalarial drug for 811 of the 1,446 patients hospitalized at the medical center from March 7 to April 8. But the drug didn’t seem to help, Schluger and colleagues reported May 17 in the New England Journal of Medicine.

As a result, “we stopped giving hydroxychloroquine sometime in April,” he says.

And yet the numbers of cases and deaths from COVID-19 in New York City have continued to fall. “If we’d taken away a lifesaving drug, you wouldn’t expect that to happen,” he says. Instead, Schluger, now a pulmonary critical care doctor and clinical epidemiologist at New York Medical College and Westchester Medical Center in Valhalla, credits old-fashioned public health measures — mask-wearing, staying home, and social distancing — for New York’s success against the virus.

Hydroxychloroquine has been tested more than any other potential COVID-19 drug but has repeatedly fallen short of expectations. Although study after study has demonstrated no benefit of hydroxychloroquine for treating people with serious coronavirus infections, some people, including President Donald Trump, still insist the drug has merit. A viral video released July 27 that made the misleading assertion that hydroxychloroquine is an effective treatment for COVID-19 spread like wildfire online.

But the overwhelming majority of scientific evidence doesn’t support that claim. It’s time to move on from hydroxychloroquine to test other drugs that may have more promise against COVID-19, Schluger and other experts say.

Wrong cells

Initial hope that hydroxychloroquine was useful in fighting the coronavirus stemmed from lab tests showing that the drug inhibits the virus’s growth in kidney cells from monkeys by blocking its entry. But it turns out that the virus doesn’t enter human lung cells in the same way.

In those initial experiments, researchers tested the drug using African green monkeys’ kidney cells, known as Vero cells. Those cells are useful for virologists because they allow growth of a wide variety of viruses, says Stefan Pöhlmann, a virologist at the German Primate Center in Göttingen. But the way SARS-CoV-2, the coronavirus that causes COVID-19, infects monkey kidney cells is different from the way it infects human lung cells, Pöhlmann and colleagues report July 22 in Nature.

To infect different types of cells, the coronavirus has at least two major possible routes of entry. In one, the virus’s spike protein (the knobby structures on its surface) attaches to ACE2 protein on the cell membrane, and then an enzyme called TMPRSS2 cuts the spike protein. That process allows the virus to inject its genetic material into the cell, where more copies of the virus are produced.

Cutting a path

The SARS-CoV-2 virus can enter cells through at least two routes, only one of which is known to respond to hydroxychloroquine. Each likely starts with the virus (red) attaching to the ACE2 protein on a host cell’s surface. In one pathway (illustrated below, at left), the enzyme TMPRSS2 cuts the spike protein, causing the cellular and viral membranes to fuse and allowing the virus’s genetic material to escape into the cell. That route, which is not blocked by hydroxychloroquine, is how the virus infects human lung cells, new studies show.

In another pathway (right), the virus latches onto ACE2 and then the cell engulfs the virus in a compartment called an endosome. To dump its genetic material into the cell, a different enzyme must cut the virus’ spike protein. That enzyme, called cathepsin L, is debilitated by hydroxychloroquine in monkey kidney cells, inhibiting an infection.

Tianling Ou et al/bioRxiv.org 2020

The second way the virus gets inside cells is via a detour through special cellular compartments called endosomes. After attaching to ACE2, the virus is engulfed by an endosome, but the pathogen needs to get its genetic material out of the compartment and into the main part of the cell. So the spike protein needs to be cleaved by an enzyme to allow the viral and cellular membranes to fuse, releasing the virus’s genetic material, says Markus Hoffmann, a virologist also at the German Primate Center.

In Vero cells from monkeys, that enzyme — called cysteine protease cathepsin L, or CatL — performs the fusion-promoting slice. But the enzyme needs a certain level of acidity to make the cut. Hydroxychloroquine and chloroquine increase the pH too much for CatL to snip the spike protein, thereby inhibiting infection.

But when Hoffman, Pöhlmann and colleagues tested the drugs in human lung cells grown in lab dishes, the virus easily slipped into the cells. That’s because in lung cells, SARS-CoV-2 takes the more direct route using TMPRSS2, which isn’t found in the monkey cells and which chloroquine and hydroxychloroquine don’t inhibit, says Michael Farzan, a virologist and immunologist at Scripps Research Institute in Jupiter, Fla.

He and colleagues posted a preprint to bioRxiv.org on July 22 also showing that hydroxychloroquine doesn’t block how SARS-CoV-2 enters human cells. That data has not yet been reviewed by other scientists for publication in a scientific journal.

Very little, if any, CatL is made in human lung cells, Pöhlmann says. That leaves the virus with mainly the TMPRSS2 route of entry, which is impervious to hydroxychloroquine.

Many other viruses, including the original SARS and MERS coronaviruses, use TMPRSS2 to activate their spike protein. But the TMPRSS2 entryway is much more important for SARS-CoV-2’s entry to human lung cells than it was for the original SARS virus, Farzan’s study demonstrates. That’s because SARS-CoV-2 also uses another enzyme called furin to snip the spike protein (SN: 3/26/20).

That furin cleavage spot was not present in the original SARS virus, and may make it easier for SARS-CoV-2 to break into cells. Such furin cleavage sites often help make influenza and other viruses more infectious. In Farzan’s study, the furin cuts make the novel coronavirus more dependent on TMPRSS2 for entry, relegating the CatL pathway to a distant plan B.

A compound called camostat mesylate effectively inhibits SARS-CoV-2 entry in cells that make TMPRSS2, both studies found. That drug is being tested against the virus in some clinical trials.

Another study from researchers in France also found that hydroxychloroquine inhibits SARS-CoV-2 infection of Vero cells, but not human lung cells. In addition, the drug did not protect another kind of monkey, cynomolgus macaques, from coronavirus infection, the researchers reported July 22 in Nature.

These results indicate the importance of using human lung cells to study the virus, the researchers say. “A lot of these [favorable hydroxychloroquine] studies that came out are sort of meaningless because they were done in the wrong cell [types],” says Katherine Seley-Radtke, a medicinal chemist at the University of Maryland Baltimore County.

Farzan says he doesn’t blame anyone for trying hydroxychloroquine first. “We were grasping at straws” at the beginning of the coronavirus outbreak, he says. “There was a good deal of just trying things on people initially … that just ended up being essentially useless.”

The new studies’ implications are clear, says Seley-Radtke, who was not involved in any of the new studies. “We now have a lot more information about hydroxychloroquine, and it doesn’t work. It’s not a direct-acting antiviral.”

That means chloroquine and hydroxychloroquine are also unlikely to prevent infection with the virus or protect people from developing serious illnesses, as some researchers had proposed. Some studies are still testing the drugs to determine whether they can prevent infection or lessen the risk of developing serious illness, although results of one such study conducted at the University of Minnesota were not encouraging (SN: 6/4/20). That study showed that hydroxychloroquine did not prevent coronavirus infections after exposure to the virus.

No help for the hospitalized

Antiviral activity aside, researchers had hoped hydroxychloroquine could calm the overactive immune system response, called a “cytokine storm,” that leads to tissue damage and even death in some COVID-19 patients. The reason for that hope is that hydroxychloroquine is also used to treat rheumatoid arthritis and lupus, and can help regulate the immune system in those patients (SN: 5/22/20).

But hydroxychloroquine and chloroquine have not panned out as effective COVID-19 therapies, Shmuel Shoham, an infectious-disease specialist at Johns Hopkins School of Medicine, said June 26 during a news conference sponsored by the Infectious Diseases Society of America announcing revised treatment guidelines. The evidence that “has come through is not encouraging that that’s going to be a great option,” he said. The U.S. Food and Drug Administration has withdrawn its emergency use authorization for hydroxychloroquine (SN: 6/15/20), and several large studies have stopped testing the drug for people who are hospitalized with COVID-19.

Compared with a placebo, hydroxychloroquine did not relieve COVID-19 symptoms or prevent people from progressing to severe illness to a statistically meaningful degree, researchers reported July 16 in the Annals of Internal Medicine. Similarly, a randomized trial in Brazil of more than 600 COVID-19 patients with mild to moderate symptoms found no statistically meaningful benefit over a placebo of either hydroxychloroquine alone or in combination with another drug called azithromycin, researchers reported July 23 in the New England Journal of Medicine.

Some studies, published after the FDA’s withdrawal, have found what appears to be a benefit of taking the drug. At Henry Ford Hospital in Detroit, researchers wanted to know how well the hospital was doing with treating COVID-19 patients. So infectious disease epidemiologist Samia Arshad and colleagues looked back at patient records from March 10 to May 2. Patients with moderate to severe disease were given hydroxychloroquine, and, if a bacterial infection was suspected, also got the antibiotic azithromycin. Overall, about 18 percent of COVID-19 patients died. That percentage was lower in the hydroxychloroquine group, with 13.5 percent dying, Arshad and colleagues reported July 1 in the International Journal of Infectious Diseases. But about 20 percent of those who got hydroxychloroquine and azithromycin died.

Arshad says their results may differ from those of studies that didn’t show a benefit because the Henry Ford patients got treatment earlier (91 percent got the drug within 48 hours of being admitted to the hospital) and because a treatment algorithm the doctors used didn’t allow anyone with cardiac risk factors to take the drug. Anyone who did get the drug was closely monitored. The hospital stopped using the drug after the FDA withdrew emergency use authorization.

Another retrospective study of almost 6,500 COVID-19 patients in New York City from March 13 to April 17 also found a reduced risk of death among people taking hydroxychloroquine, researchers reported June 30 in the Journal of General Internal Medicine.

That’s not enough to recommend hydroxychloroquine for use against the coronavirus, says David Hsieh, an oncologist at the University of Texas Southwestern Medical Center in Dallas, who has been examining clinical trials of COVID-19 around the world.

He and his brother Antony Hsieh of the Perelman School of Medicine at the University of Pennsylvania, and UT Southwestern colleague Magdalena Espinoza found that hydroxychloroquine has had more coronavirus clinical trials devoted to it and is mentioned in more publications than any other drug or therapy directed at COVID-19, the researchers reported July 4 in Med.

First place

Hydroxychloroquine has been studied more than any other potential COVID-19 drug, a search of scientific literature databases reveals. Preclinical studies, which examined a drug’s activity in animals or in cells grown in lab dishes, are indicated in red. Other studies, including results of clinical trials, are shown in blue.

Most studied potential COVID-19 drugs

D. Hsieh et al/Med 2020

Studies that look back at outcomes, such as retrospective studies and meta-analyses (studies that combine data from multiple studies) are great for generating hypotheses, Hsieh says. “But we’re in real danger if we start using [them] to change our practice.”

That’s because in retrospective or observational studies, there is no guarantee that patients who got the drug and those that didn’t are the same. In the Henry Ford trial, patients that got hydroxychloroquine were about five years younger, on average, than those who didn’t, Schluger says. “We know that age is the single strongest predictor of mortality from this illness.”

And the patients who got hydroxychloroquine were also more likely than those not on the antimalarial drug to have also gotten steroids, which other studies have demonstrated can be lifesaving (SN: 7/22/20). So the patients who got the drug were different from those who didn’t in important ways.

Researchers “who have looked at the data carefully consider the hydroxychloroquine story to be pretty much over,” Schluger says. “It would be a shame if we weren’t trying other potentially promising things because we were hung up chasing down something for which there’s a lot of evidence now that it doesn’t really do much.”

About this story

Why are we doing this story?

Hydroxychloroquine has become highly politicized. As new data come to light, we at Science News share it with our readers, regardless of whether the news is good or bad. I would prefer to be able to share good news about progress against the coronavirus, but the weight of scientific evidence has tipped decidedly against hydroxychloroquine.

Where did the idea come from?

I was already preparing an update of possible therapies for COVID-19 as part of our ongoing coronavirus coverage. On July 22, three independent scientific studies reported strikingly similar results suggesting that the drug doesn’t work as an antiviral in lung cells. Then the drug was thrust into the news again by a viral video. It was clear that hydroxychloroquine needed its own story now.

How did we take steps to be fair?

I reached out to researchers who had done a retrospective study that found a benefit to taking hydroxychloroquine. I interviewed a doctor who previously prescribed the drug to COVID-19 patients, but found it unhelpful. I also interviewed scientists involved in the studies cited in the story and scientists who were not involved in the studies mentioned for independent evaluation of the evidence.

— Tina Hesman Saey

What’s this box? Learn more about it and our Transparency Project here. Can you help us by answering a few brief questions?

Coronavirus outbreak at a Georgia overnight camp infected over 200 kids and staff

Fri, 31 Jul 2020 21:55:36 GMT

A coronavirus outbreak at an overnight summer camp in Georgia suggests that children of any age are susceptible to the virus and might have a key role in spreading it.

At least 260 out of 597 attendees and staff members tested positive for the coronavirus, including campers younger than 10, researchers report in the July 31 Morbidity and Mortality Weekly Report. Younger children had the highest attack rates, or the total number of new cases per a specific group. Just over half of kids ages 6 to 10 tested positive.

“This investigation adds to the body of evidence demonstrating that children of all ages are susceptible to [coronavirus] infection and, contrary to early reports, might play an important role in transmission,” the researchers write. Most infected people didn’t have symptoms, which may have helped the virus spread undetected.

At the camp, a teenage staff member developed symptoms on June 22 — a day after campers arrived — and left the next day. On June 24, that teen’s coronavirus test result came back positive, and officials began sending attendees home. The camp was officially closed on June 27.

Overall, 44 percent of people at the camp were infected with the virus, most of whom were campers. Kids’ ages ranged from 6 to 19 years old.

Not everyone at the camp had test results available for analysis. Since some people were not tested or their test results were not reported, the number of people infected might have been underestimated, the researchers write.

Camp officials had required anyone at the camp to provide proof of a negative coronavirus test conducted within 12 days of arriving. Campers also participated in activities like singing in clusters — made up of kids staying in the same cabin. Although all trainees and staff were required to wear cloth masks, campers were not. Staff also did not keep windows and doors open to ensure buildings were well-ventilated.

It is still unclear how much of a role that children play in coronavirus transmission. Some contact tracing studies have suggested that kids younger than 10 are less likely than people in any other age group to transmit the virus to others. But younger people are more likely to have milder symptoms, and many cases in kids might go undetected (SN: 6/3/20).

Human sperm don’t swim the way that anyone had thought

Fri, 31 Jul 2020 18:00:00 GMT

Sperm have long fooled scientists. Instead of swimming straight by twirling their tails like propellers, human sperm flick their tails lopsidedly and roll to balance out the off-center strokes.

Over 300 years ago, microscopy pioneer Antonie van Leeuwenhoek described sperm tails swaying in a symmetric pattern, like “that of a snake or an eel.” The prevailing view that sperm tails move in a balanced way, however, doesn’t capture what actually happens in three dimensions, researchers report July 31 in Science Advances.

High-speed 3-D microscopy of human sperm swimming freely in the lab revealed that the cells corkscrew as they move, consistent with previous studies. The sperm almost seemed to be drilling into the surrounding fluid, says Hermes Gadêlha, a mathematician at the University of Bristol in England.

Contrary to what people have thought, sperm tails don’t beat symmetrically. High-speed 3-D microscopy and mathematical analyses reveal that the tails wiggle to only one side as the cells roll. The combination of movements keeps sperm swimming straight ahead.

Using automated tracking of swimming sperm and mathematical analyses of position data, Gadêlha and colleagues broke sperm tail movement down into two components. Surprisingly, one was a wiggle to only one side of the cell. It’s like someone swimming using just one side of the body, Gadêlha says. By itself, such a lopsided stroke would lead to swimming in circles.

But a second component of tail movement causes the sperm to rotate, balancing out the lopsided strokes. From above, the sperm tail looks like it is beating symmetrically, as has been described historically. But a more complex, 3-D movement keeps the sperm swimming straight ahead.

The new 3-D measurements are a big step forward in understanding sperm movement, says Allan Pacey, a male fertility specialist at the University of Sheffield in England. Additional investigation is needed, though, to know if sperm move the same way in the female reproductive tract, where they must contend with fluid movement and narrow passages to reach the egg (SN: 2/13/19). Such research may inform diagnosis and treatment of human infertility, Pacey says.

To save Appalachia’s endangered mussels, scientists hatched a bold plan

Fri, 31 Jul 2020 15:00:00 GMT

The emergency surgery took place in the back of a modified pickup truck in a McDonald’s parking lot in Pikeville, Ky. This scrappy plan to rescue a species of mussel on the edge of extinction made perfect sense: Meet somewhere between Indian Creek in Virginia, where the last known wild golden riffleshells lived, and Kentucky’s Center for Mollusk Conservation in Frankfort, where they would be saved.

The strategy was a malacologist’s version of a Hail Mary pass. One scientist would gingerly pry open three golden riffleshells and remove their larvae to be nurtured in his lab. The other would return the three mussels to Indian Creek, and wait for the day he could introduce their grown offspring to the same habitat. If the plan didn’t produce enough offspring to sustain a new population, the mussels would probably vanish.

Five years ago, Indian Creek was the only known remaining habitat for the golden riffleshell (Epioblasma florentina aureola). And like many other mussels, this bivalve’s future looked bleak. Biologists estimated that only about 100 remained in the wild. “They were the next species on the list for disappearing from the face of the Earth,” says biologist Tim Lane, who leads mussel recovery efforts at the Virginia Department of Wildlife Resources’ Aquatic Wildlife Conservation Center, near Marion. “We were literally watching the last of them.”

Seeing a species vanish in real time is difficult, he says, and is in some ways worsened by the mussels’ near-invisibility beneath the surface. “They’re not charismatic like, say, the northern white rhino,” he says. When mussels go extinct, almost no one knows — or mourns them.

The survival of mussel 6420 and thousands of its siblings started with an interstate rescue plan hatched by biologist Tim Lane.Gary Peeples/USFWS

An avid amateur photographer who takes pictures of mollusks, snails, fish and various other small critters in the wild, Lane spends much of his time floating facedown in Appalachian waterways, suspended over rocky riverbeds like a float in the Macy’s Thanksgiving Day Parade. He came up with the plan and carried out phase one: delicately prying the bivalves from the Indian Creek river-bed and laying them in a cooler filled with pebbles, dirt and river water for the 90-minute trip to Kentucky.

A full-grown golden riffleshell is about the size of a small biscuit, with a yellowy, fan-shaped case. Like other mussels, it anchors itself in gravel with a fleshy foot and rarely moves more than a few meters during its lifetime, which could last 15 years or more. The sedentary creatures have been listed as a federally endangered species since 1977.

Malacologists, like Lane and others who study mollusks, are accustomed to championing underdogs. More than two-thirds of all identified North American freshwater mussel species are extinct or endangered. North America has the greatest diversity of freshwater mussels — with a heavy concentration in the Southeast. Tennessee’s Clinch River hosts about twice as many species as all of Europe.

In every locale, the mussels’ problems arise from a mix of factors. Until about a century ago, enormous mussel populations thrived in the Midwest and Southeast, and mussels were often harvested to make shell buttons. But the construction of dams in major rivers divided these populations and separated the creatures from the fish that carry their larvae. “The dams suffocated the huge mussel beds in the most productive habitats,” says Paul Johnson, who runs Alabama’s Aquatic Biodiversity Center, in Perry County.

Adding insult to injury, rampant pollution from industrial dumping and chemical spills led to massive die-offs before the 1972 Clean Water Act led to cleaner waterways. The animals have faced other threats, too, including microbial pathogens and predators.

Just last December, more than 150 kilometers downstream of the confluence of Indian Creek and the Clinch, biologists with the U.S. Fish and Wildlife Service reported a massive die-off of pheasantshells (Actinonaias pectorosa) where the river passes through the town of Kyles Ford, Tenn. The researchers suspect some pathogenic fungi, bacteria or parasites are to blame. Myriad species in Europe and the Pacific Northwest, including the freshwater pearl mussel (Margaritifera margaritifera) and the depressed river mussel (Pseudanodonta complanata), have experienced similar die-offs.

Against that backdrop of known and unknown hazards, researchers around the world are combining in vitro propagation, months of tedious observation and exhaustive laboratory trial and error to save these animals. But none of these evolving methods offer a quick fix.

“It took us 100 years to get into this mess,” Johnson says. “It’s not going to take 10 to get out of it.”

A small group of biologists is getting creative to save freshwater mussels, animals that do a yeoman’s job of cleaning rivers.Gary Peeples/USFWS

River cleaners

Those who study and try to save mussels feel an irresistible calling, says Jessi DeMartini, a biologist in Illinois who works on mussel conservation in the Forest Preserve District of DuPage County. “It’s an addiction … that becomes a passion.” They see mollusks as the uncelebrated heroes of the world’s rivers.

Mollusk shells stabilize riverbeds and create habitats for other creatures. The bivalves provide food to raccoons, muskrats and other critters. Most importantly, mollusks are nature’s water filters, able to clean up big messes.

A single mussel can filter more than 50 liters of water per day, removing algae and pollution, including toxic substances dumped into rivers as industrial waste. Some researchers suspect that the ability to sop up toxic metals is contributing to the animals’ decline. Like canaries in coal mines, if a mussel population suddenly plummets, it’s a sign that something’s gone foul in the water. (Malacologists describe the smell of a living mussel as rich and sweet, like the river it comes from. But find a dead mussel and the stench is so bad you’d wish you had been born without a sense of smell.)

50+

liters

Amount of water a single mussel can filter in a day

By observing the health of juvenile mussels and analyzing tissue samples, researchers can effectively monitor water quality and acute die-offs, Monte McGregor, director of Kentucky’s Center for Mollusk Conservation, and others reported in December 2019 in Freshwater Science.

The effort to save mussels has implications far beyond the rural and rugged riverways of Appalachia. More than two-thirds of U.S. homes get their drinking water from rivers, Johnson notes. Mussels provide an inexpensive way to safeguard that resource and do some of the work of water treatment plants. “Mussels allow us to provide cleaner water on a less per-cost basis,” he says.

For all these reasons, conservation biologists keep returning to the rivers and take hope where they can find it. The golden riffleshell has been particularly vexing. To even begin the process of mussel propagation, which has a high rate of failure, biologists typically need to start with larvae, also known as glochidia. The golden riffleshell’s dwindling numbers mean that finding a gravid female — one filled with glochidia — is a rare occasion. But on an April morning in 2016, hope came with a find by Sarah Colletti, a mussel-loving biologist also at Virginia’s Aquatic Wildlife Conservation Center. Colletti had joined a small squad of biologists who donned tall rubber waders and spent hours hunched over viewscopes, which look like toy telescopes, pointed down into water to make it easy to tell rocks from mussels. Colletti was scanning the bottom of Indian Creek as part of what’s become an annual ritual, the search for the last remaining golden riffleshells.

Biologist Sarah Colletti found three gravid golden riffleshell females in Virginia’s Indian Creek in 2016, setting off a chain of events that might give the endangered species a chance at survival.G. Peeples/USFWS

It’s a monotonous pursuit, she says, and “you’re second-guessing every rock.” When a mussel comes into view, “it’s kind of shocking.”

Through her viewscope, Colletti spotted three golden riffleshells nestled among the rocks and silt. All were females displaying their lure, a section of tissue that resembles a tasty meal. Those exposed lures meant the mussels were gravid, ready to release millions of glochidia. Finding three gravid females was unusual. The biologists saw an opportunity — maybe one of the last — to help.

Alluring display

Just getting to the larval stage is an accomplishment for these bivalves. Eggs become fertilized only when females filter sperm released into the water by upstream males.

Glochidia, each the size of a grain of salt, can’t survive on their own. They have to clamp onto the gills of a host fish and become parasitic passengers, embedding themselves in the gill tissue and thriving on a mix of nutrients in the water and in fish blood until undergoing a kind of metamorphosis.

As mussels grow their first shells and become juveniles, they swell to the size of a well-fed deer tick, then drop from the fish. For each species of mussel, there’s often only one — or at most, a few — species of fish that can ferry larvae to the next stage of life.

Mussels have evolved a staggering array of methods for infesting fish; almost all involve deception. Some mussels disguise their glochidia in alluring packages that look like minnows; others unspool wormlike appendages tipped with packets holding millions of larvae. The rainbow mussel (Villosa iris) has a lure that looks like a crawfish skittering along the river floor. When a fish tries to eat the minnow or worm or crawfish, the fish gets a mouthful of glochidia, released like dandelion seeds. With the fish’s next gulp of water, the glochidia wash over the gills and stick.

What looks like a tasty, spotted minnow is actually part of a Lampsilis mussel. When a fish goes in for a bite of this lure, it inhales a mouthful of mussel larvae that attach to the fish’s gills and grow into juveniles.M. Christopher Barnhart

Members of the genus Epioblasma, including the golden riffleshell, have perfected a tactic that earned them the nickname “fish snapper.” The ritual begins when a mother mussel sends out a short thread, the end of which looks like a bug. When a hungry fish swims in for a bite, the shell snaps shut around the fish’s head and holds tight with short, sharp teeth just inside the shell’s rim. As the fish chokes, it inhales the glochidia, which install themselves in the gills. After a few minutes, the mussel relaxes and releases its captive. The fish that survive are stunned; smaller fish (which aren’t good hosts anyway) may die, their heads crushed by the mollusk’s snap.

The handoff

All the pieces of this choreographed sequence — fertilization to glochidia formation to infestation of a host — have to happen in just the right way, says McGregor, who with fellow Kentucky biologist Leroy Koch was waiting at the McDonald’s for Lane to arrive. “There are lots of strikes against these mussels,” he says. “The glochidia have to hit the right fish at the right time.”

Ideally, mussels would reproduce on their own and people wouldn’t have to intervene. Malacologists step in when a species looks like it’s on the brink of extinction.

A snuffbox mussel snaps shut on the head of a rainbow darter, giving the snuffbox larvae, or glochidia, enough time to attach to the fish’s gills.M. Christopher Barnhart

A closeup photo shows nearly clear glochidia of an oyster mussel attached to the pink gills of a logperch.M. Christopher Barnhart

That morning in April, Colletti marked the location of the mussels in the stream with three large stones and a bright orange flag. She phoned Lane, who had spent much of graduate school studying the diversity of life in Appalachian rivers. The golden riffleshell always seemed to be foundering. In previous years, when they found gravid females in Indian Creek, Lane and colleagues had attempted streamside infestations: catching host fish and manually transferring glochidia from the mussel into the fish gills. But the approach didn’t work.

Lane called McGregor, who was well-known in the close-knit malacology community for having pioneered in vitro approaches to bring bivalves back. Biologists have sent him glochidia in test tubes via UPS and FedEx; he’s also been known to drive for hours to secure the larvae. At Kentucky’s Center for Mollusk Conservation, he closely monitors the temperature and quality of the water that flows through the lab, and he makes his own food for the mussels — often customizing a recipe to fit the needs of a species. After Lane called and proposed the plan, McGregor agreed to meet in Pikeville and carry out the glochidia-removing procedure in what he calls his “mobile lab” (the topped bed of his Ford F-250 super duty crew cab).

Surgery took no more than 30 minutes per mussel. McGregor pried open the shell about five millimeters with his fingers, and used a silicone wedge to keep it open. Then, he filled a syringe with sterile water and flushed out the glochidia from the mussels into a lab dish. All the while, he had to pay attention to the patient and keep it cool.

“You have to handle the mussel properly,” McGregor says. If the animal gets too warm, that could imperil both the larvae and the mother.

Once the procedure was over, Lane replaced the mussels in the cooler and drove east to return them to Indian Creek. McGregor drove west, escorting thousands of golden rifflleshell larvae over 260 kilometers of twisting mountain roads, to the mussel recovery operation with the longest track record for propagating mussels in the lab without host fish. This would be the golden riffleshell’s best chance at survival.

Take me to the river

For nearly 20 years, researchers at the Kentucky facility have worked on bringing mussels back from the brink of extinction. The small collection of buildings sits near Elkhorn Creek, but McGregor says the water is often too polluted to use for the tanks that hold mussels during the most sensitive part of their development. The pollutants include raw sewage. “We can’t grow mussels in raw sewage,” he says.

If such a thing as “artisanal algae” exists, it’s surely the stuff grown in this lab. Researchers grow algal cultures in giant incubators. McGregor has grown many algal varieties and has spent years matching the right algal slime to the right mussel.

Biologists have developed methods of propagating endangered mussel species in the lab, even without the host fish. To remove glochidia, scientists first pry open the shell.T. Lane

Then a scientist holds open the mussel shell with a silicone wedge to flush out the larvae with sterile water.T. Lane

McGregor learned the basics of in vitro propagation in 2004 from Robert Hudson, a malacologist at Presbyterian College in Clinton, S.C. By 2016, McGregor had spent more than a decade improving his recipe, finding the right mix of algae, nutrients and rabbit serum to feed glochidia. Although he prefers to use host fish to grow mussels — and the lab contains dozens of tanks that hold fish as hosts for some other species — scientists have so far been unable to identify the fish that can carry golden riffleshell larvae (which is why streamside infestation doesn’t work).

So McGregor had to grow the larvae without a host. After 18 days in an incubator with McGregor’s custom-made mussel-growing cocktail, about 1,600 larvae survived to become juveniles. They were transferred to silt-lined raceways with cool flowing water to simulate a river. Within a few months, the glochidia had grown to the size of nickels — large enough to survive in the wild.

McGregor divided the spoils. “It was too risky for me to keep them all,” he says. He sent groups of mussels back over the mountains to two facilities in Virginia. One is the Aquatic Wildlife Conservation Center, where Colletti and colleagues have been studying and cultivating the bivalves. In a typical year, researchers there release up to 10,000 lab-grown mussels into the wild, representing up to 10 species.

Colletti says she sees signs of hope for the golden riffleshell. Today, the progeny of those three mussels she found in 2016 are producing their own glochidia in the lab. “They were able to become gravid in captivity,” she says. Lane recently sent photos of those larval grandchildren to McGregor. Colletti and Lane hope the young mussels released into the river will do as well.

There are other, scattered success stories emerging from recent mussel projects. Johnson, in Alabama, has spent years studying the pale lilliput (Toxolasma cylindrellus).

After more than two years of work, Johnson pegged the northern studfish (Fundulus catenatus), which looks like a larger, prettier version of a minnow, as the pale lilliput’s host. Once he made that connection, Johnson began to infest a host fish to cultivate new populations of the endangered species.

There are also big risks. Last year, Johnson propagated about 5,000 juveniles of the rare Louisiana pearshell mussel (Margaritifera hembeli). But just before he was going to release juveniles into a Louisiana river, disaster struck. On an unusually hot spring morning, the temperature of the water streaming into his facility’s raceways soared, killing thousands of the mussels before a researcher could close the valve. “One bad day can literally wreck several years of work,” Johnson says.

He was left with only about 100 animals to return to nature. But those animals have been thriving in the lab. Johnson has grown new batches and plans to restore them to their natural habitat next year. It’s too soon to declare victory, he says, but he’s hopeful.

This gravid golden riffleshell began as a larva in Indian Creek, grew up in a Kentucky lab and is now in a Virginia lab. Its parted shell reveals pouches containing tiny larvae ready to infest an unwitting host fish.T. Lane

The ultimate goal in mussel conservation, Johnson says, is to propagate animals that can complete an entire life cycle. That means glochidia get to the host fish, survive the tumultuous juvenile years and mature enough to reproduce. In the wild, the whole process takes a few weeks to a few months. In the lab, the timescale is bigger. “It’s a decadeslong effort,” he says.

Hundreds of the next generation of golden riffleshells are now back at home, with two populations in the Clinch River and one in Indian Creek since 2017. These mussels now measure about the size of a quarter, though some are bigger. Of the 700 that Lane, Colletti and others installed in the wild, many have died and some are unaccounted for, but the researchers estimate that about 300 are still alive.

The scientists placed transponders on about 100 of the mussels, and every year Lane and Colletti return for a census, waving a device that looks like a metal detector over the water surface and waiting for the satisfying chirp that indicates a lab-grown riffleshell is found.

For now, the rescue of the golden riffleshell remains a good news story, but Lane says malacologists have to remain vigilant. “This gives us some time, but it’s not like we can pat ourselves on the back and stop.” To ensure the survival of the species, biologists will need to continue harvesting glochidia, shepherding mussels to the juvenile stage and returning them to the wild, year after year. The ultimate goal is to build a population that can sustain itself and reproduce without human intervention, rabbit serum or emergency surgery outside a rural McDonald’s.

This parasitic plant consists of just flashy flowers and creepy suckers

Fri, 31 Jul 2020 10:00:00 GMT

Doorknobs in skirts. Microphones in tutus. There are lots of ways to describe Langsdorffia flowers, but parasitic-plant specialist Chris Thorogood says they “absolutely look to me like deep-sea creatures.”

Whatever you compare them to, the flowers are intricate, screaming red showpieces. That’s the total opposite of the unshowy rest of the plant. It has no leaves, just grayish, ropelike tissue that probes through soil and ranks in looks somewhere between blah and dried-up dog droppings.

The mix of flashy sexual parts and super-simplified other structures makes sense for the plant kingdom’s extreme parasites, including the four known Langsdorffia species. Why grow a lot of greenery to feed yourself when you can steal what you need (SN: 8/23/16)?

“They’re vampire plants,” says Thorogood, at the University of Oxford Botanic Garden & Arboretum. Langsdorffia’s underground rope sucks all the nutrition it needs from the roots of other plants, such as figs and mimosas. The burrowing freeloaders “challenge our notion of what plants even do,” he says.

Scraping soil away from a Langsdorffia hypogea reveals the plant’s scam: It’s just a bouquet of flowers growing from ropy vampiric tissue that sucks on other species’ roots.Jean Carlos Santos

Spotting such marvels requires finding just the right wild spot. Neither Oxford nor any other botanic garden grows them, and Thorogood has never seen a live one, he lamented in a Langsdorffia profile in the May 2020 Plants People Planet. But his lucky coauthor, ecologist Jean Carlos Santos, has.

The flowers of L. hypogea species pop out of the ground here and there in Central and South America, including Brazil’s savanna, the cerrado. “Imagine the visual impact,” says Santos, of Universidade Federal de Sergipe in São Cristóvão, Brazil. The flowers bloom during the dry season, erupting in loud reds from a thin carpet of other plants’ dead, brown leaves.

Unlike many flowers from apples to zinnias that sport both male and female parts, an individual L. hypogea plant is either all male or all female. Each of its knobby blooms burst from the soil as skirted masses of tiny same-sex nubbins. To attract the vital go-between pollinators, males ooze nectar among the nubbins. Females release it from their skirt and in a sweet zone at the base of the main bouquet. It’s a banquet in a parched season. Ants, beetles, cockroaches and even birds such as white-naped jays gather to feast.

Beetles probably do some actual pollination for the plant, says Santos, who studies insect-plant interactions. But ants and most of the other guests are probably just freeloaders themselves on this freeloading plant.

Blooming is an extraordinary event, and shows that even for a thief stripped to essentials, elaborate floral sex is apparently still worth the effort. Though, some observers have suggested, it may happen only once in each Langsdorffia lifetime.

The physics of solar flares could help scientists predict imminent outbursts

Thu, 30 Jul 2020 18:16:00 GMT

Space weather forecasting is a guessing game. Predictions of outbursts from the sun are typically based on the amount of activity observed on the sun’s roiling surface, without accounting for the specific processes behind the blasts.

But a new technique could help predict the violent eruptions of radiation known as solar flares based on the physics behind them, researchers report in the July 31 Science. When applied to old data, the method anticipated several powerful flares, although it missed some as well.

Radiation released in solar flares and associated eruptions of charged particles, or plasma,can be harmful. This space weather can disrupt radio communications, throw off satellites, take down power grids and endanger astronauts (SN: 9/11/17). More accurate forecasts could allow operators to switch off sensitive systems or otherwise make preparations to mitigate negative effects.

Current prediction methods rely on tracking flare-linked phenomena such as large, complex sunspots — dark regions on the sun’s surface with powerful magnetic fields. But that leads to some false alarms.

In contrast, the new prediction method is rooted in the intricacies of how and when the sun’s tangled loops of magnetic fields rearrange themselves, in a process known as magnetic reconnection, releasing bursts of energy that mark solar flares.

On the sun’s surface, magnetic fields can get gnarly. Magnetic field lines, imaginary contours that indicate the direction of the magnetic field at various locations, loop and cross over one another like well-mixed spaghetti. When those lines break and reconnect, a burst of energy is released, producing a flare. The details of how and under what conditions this happens have yet to be unraveled.

In the new study, physicist Kanya Kusano from Nagoya University in Japan and colleagues propose that the largest flares result when two arcing magnetic field lines connect, forming an m-shaped loop, as a smaller loop forms close to the sun’s surface. This “double-arc instability” leads to more magnetic reconnection, and the m-shaped loop expands, unleashing energy.

Using 11 years’ worth of data from NASA’s Solar Dynamics Observatory spacecraft, the researchers identified regions on the sun with high magnetic activity. For each region, the team determined whether conditions were ripe for a flare-inducing double-arc instability, and then aimed to predict the most powerful flares the sun produces, called X-class flares. The technique correctly predicted seven of nine flares that passed a threshold that the researchers chose, called X2, the second strength subdivision of the X-class.

The successful predictions suggest that researchers may have identified the physical process that underlies some of the largest outbursts.

“Prediction is a very good benchmark for how well we can understand nature,” Kusano says.

The unsuccessful predictions are likewise illuminating: “Even if it fails, it tells us something,” says solar physicist Astrid Veronig of the University of Graz in Austria, who wrote a commentary on the result, also published in Science. The two flares that the technique missed had no associated ejection of plasma from the sun’s surface. “This kind of instability is maybe not a good way to explain these other flares,” Veronig says. They may instead have resulted from magnetic reconnection high above, instead of close to, the sun’s surface.

The mechanism on which the researchers based their prediction “is really interesting and very insightful,” says solar physicist KD Leka of NorthWest Research Associates in Boulder, Colo. But, she notes, the method couldn’t predict how soon the flares will occur — whether the burst would come an hour or a day after the right conditions first occurred — and it didn’t identify slightly weaker X1 flares, or the next class down, known as M-class flares, which could still be damaging.

“The mantra that I live by,” Leka says, “is any rule you think you’ve figured out about the sun, it’s going to figure out how to break it.”

Many U.S. neighborhoods with the worst air 40 years ago remain the most polluted

Thu, 30 Jul 2020 18:00:00 GMT

Not all air is created equal.

While air quality has improved across the United States in recent decades, significant disparities persist in terms of who breathes the worst air. Communities exposed to the most air pollution in the 1980s — often poor and with high proportions of Black and Hispanic residents — are largely in the same position today, researchers report in the July 31 Science.

Lots of different pollutants can clog the air, but scientists are especially interested in particulate matter less than 2.5 microns in diameter. Called PM2.5, the tiny particles are associated with myriad health problems, including cardiovascular disease, respiratory illness, diabetes and neurological problems (SN: 9/19/17).

Marginalized communities, often closer to factories or major roadways than whiter, wealthier communities, bear the brunt of PM2.5 pollution. That exposure contributes to stark racial health inequities in the United States. “There hasn’t been clear documentation of how these disparities have evolved over time,” says Jonathan Colmer, an economist at the University of Virginia in Charlottesville. The U.S. Environmental Protection Agency only began measuring PM2.5 in 1999. Addressing current inequities requires an understanding of the past, Colmer says.

He and colleagues estimated annual average PM2.5 levels for each square kilometer in the country from 1981 to 2016 using published data derived from satellites and simulations of pollutant movement through space. The team then mapped those estimates onto about 65,000 census tracts to rank neighborhoods from most to least polluted annually, and noted how rankings changed over time.

Whereas average PM2.5 concentrations decreased by 70 percent across the entire country, the relative ranking of neighborhoods hardly budged.

On average, whiter, more affluent neighborhoods were less polluted throughout the 36-year time frame. Disadvantaged neighborhoods with more Black or Hispanic people remained more polluted, despite experiencing a larger absolute drop in PM2.5 levels.

“It’s really good news that air pollution is dropping for everyone,” says Anjum Hajat, an epidemiologist at the University of Washington in Seattle who wasn’t involved in the research. But even relatively low levels of pollution pose significant health risks, and the reductions might not translate to improved health for the hardest-hit communities. “To me, the take-home message is that inequity is very stubborn.”

The study wasn’t designed to address why these inequities persist, though a move away from manufacturing or coal production was associated with air quality improvements in certain neighborhoods.

More important, Hajat says, is power structure. “The communities that were the most marginalized and had the least political power in the 1980s are likely the same communities that continue to have the least power today.”

White, wealthy communities have been able to prevent polluting facilities from being placed in their communities, she says, while marginalized communities often haven’t had this power. To see real change, “marginalized communities need to be included in discussions about their future,” she says, for instance through community members holding decision-making roles.

An immune system quirk may help anglerfish fuse with mates during sex

Thu, 30 Jul 2020 18:00:00 GMT

For deep-sea anglerfishes, sex resembles an organ transplant. It’s hard to find a partner in the dark depths, so a tiny male anglerfish fuses its tissues to a more massive female during mating, allowing the two to share not only sperm but even blood and skin (SN: 7/26/75). The creatures are the only animals known to mate in this parasitic way.

How males and females fuse and avoid being rejected by each other’s immune systems — like a mismatched organ transplant — has been a mystery. Now, a study finds that anglerfish might not have to evade the immune system in the first place. Some species lack key genes involved in the body’s immune response, which may make fusion without deadly consequences possible, researchers report online July 30 in Science.

In vertebrates, immune protection typically involves a bodily response called adaptive immunity that identifies and eliminates foreign threats like viruses. Immune cells, such as T cells, recognize fragments of invaders and present those pieces to other cells that then mount an attack. In another line of defense, proteins called antibodies bind to trespassers to mark them for removal by the immune system. In organ transplants, such responses can cause the new organ to fail.

The deep-sea anglerfishes’ missing genes are involved in making those systems work.

“When you look at [these fish], you scratch your head and think, ‘How is that possible?’” says Thomas Boehm, an immunologist at the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany. In humans, it’s often difficult to find the right match for organ transplants because of the adaptive immune system, “but these creatures seem to be doing it without knowing what’s going on.”

Boehm and colleagues isolated DNA from 31 preserved anglerfish representing 10 deep-sea species. In four of the species, males attach to females only temporarily. In the other six, the fusion is permanent, with either one or multiple males attached to a single female. The researchers also scanned the genetic blueprints of three species that live in shallow waters and don’t attach during mating.

Two deep-sea anglerfish species, including Photocorynus spiniceps (a preserved female is shown with a tiny male attached on her back), don’t have genes involved in developing antibodies or immune cells that identify invaders and kill foreign or infected cells.Theodore W. Pietsch/Univ. of Washington

Compared with anglerfishes that don’t fuse to their mates, species that fuse are missing genes that help produce new antibodies that get better at binding to perceived threats in future encounters. Not having those antibodies might be helpful for a female that is exposed to multiple males throughout life, Boehm says. Some anglerfishes that unite permanently also lack genes needed to make the parts of T cells that help identify foreign tissue and pathogens.

Two of the species in which multiple males can attach to a single female — Photocorynus spiniceps and Haplophryne mollis — may not make antibodies at all. “If I had to diagnose [those two fish] … I would say, ‘OK, this is red alert, we really have to do something because this is severe combined immunodeficiency. Fatal prognosis,’” Boehm says. People with severe combined immunodeficiency — a condition in which genetic defects result in a weak immune system — often die within the first year of life.

The researchers didn’t do any laboratory experiments to confirm how the missing genes might affect the immune system’s behavior. Without such data, it’s hard to know what the lack of these genes means for things like fighting off pathogens. “How are they balancing … reproduction and response to infections?” asks Natalie Steinel, an immunologist at the University of Massachusetts Lowell. “It seems, at least genetically, that they’ve put all their chips on reproduction.”

The researchers’ findings highlight the various forms creatures’ immune systems can take — not only within vertebrates at large, but also within a single group of fishes, Steinel says. “It’s really interesting to see the diversity of immune systems within these different species.”

It’s possible, though not probable, that anglerfishes have an adaptive immune system that is completely different from that of other vertebrates. Or the creatures may have evolved a nonspecific immune response that protects them from infections but not parasitic sex.

The fish “must have done something to compensate for adaptive immunity,” Boehm says. “We don’t know what that is, but that is for the future.”

The Perseverance rover caps off a month of Mars launches

Thu, 30 Jul 2020 11:56:38 GMT

NASA’s Perseverance rover took off at 7:50 a.m. EDT on July 30 from Cape Canaveral, Fla., and is now on its way to Mars with a suite of instruments designed to search for ancient life. The launch is the third this month of spacecraft en route to the Red Planet.

This is the 22nd spacecraft NASA has aimed at Mars (16 of those missions were successful). But Perseverance will be the first mission to cache rock samples from the Red Planet for a future mission to bring back to Earth.

It will also be the first NASA mission in more than 40 years to directly search for life on Mars. The rover will land in a region called Jezero crater (SN: 7/28/20). That crater was once an ancient lake bed, and scientists think its rocks and sediments could preserve signs of life, if life was ever there (SN: 7/29/20). The spacecraft will take video and audio recordings of its own landing as it touches down — another first for a NASA Mars mission.

“This mission has more cameras on it than any we’ve ever sent before,” said Lori Glaze, director of NASA’s Planetary Science Division, on July 30 during a news conference. “It’s going to feel like we’re actually there, riding along with Perseverance on the way down.”

Perseverance, shown here in an artist’s illustration, will seek signs that Mars once hosted alien life.JPL-Caltech/NASA

Mars launches tend to come in clumps thanks to Mars’ and Earth’s orbits. The planets line up on the same side of the sun every two years, so scientists have narrow windows to launch for the most efficient trip. All three of this year’s missions will arrive in February 2021.

The other missions launched in July represent firsts for their respective countries. The United Arab Emirates’ first interplanetary mission, which carries an orbiter called the Hope Probe, launched from Japan on July 19. Hope will measure Mars’ weather, from daily temperature changes to the significance of dust in the planet’s atmosphere (SN: 7/14/20).

Next up was China’s first Mars mission, Tianwen-1, which means “questions to heaven” and launched on July 23. China has previously sent spacecraft to orbit and land on the moon (SN: 1/3/19). And it is the first nation to send an orbiter, lander and rover all at once on its first attempt to reach Mars. “No planetary missions have ever been implemented in this way,” mission scientists wrote July 13 in Nature Astronomy. “If successful, it would signify a major technical breakthrough.”

Tianwen-1’s lander and rover will touch down in Utopia Planitia in April 2021. Instruments on the rover and lander will test Mars’ soil composition and magnetic and gravitational fields and will probe Mars’ interior.

Utopia Planitia is the same region where the first long-lived Mars lander, NASA’s Viking 1, touched down in 1976 (SN: 7/20/16). Viking was the first spacecraft to search for life on Mars, but its results were inconclusive. Perhaps with the rush of spacecraft this year, and the plans to bring red rocks home, scientists will finally learn whether Mars ever did — or does — host alien life.

An Antarctic ice dome may offer the world’s clearest views of the night sky

Wed, 29 Jul 2020 15:00:00 GMT

An observatory in the heart of Antarctica could have the world’s clearest views of the night sky.

If an optical telescope were built on a tower a few stories tall in the middle of the Antarctic Plateau, it could discern celestial features about half the size of those typically visible to other observatories, researchers report online July 29 in Nature. The observatory would achieve such sharp vision by peering above the atmosphere’s lowermost layer, known as the boundary layer, responsible for much of the undulating air that muddles telescope images (SN: 10/4/18).

The thickness of Earth’s boundary layer varies across the globe. Near the equator, it can be hundreds of meters thick, limiting the vision of premier optical telescopes in places like the Canary Islands and Hawaii (SN: 10/14/19). Those telescopes usually cannot pick out celestial features smaller than 0.6 to 0.8 arc seconds — the apparent width of a human hair from about 20 meters away.

“But in Antarctica, the boundary layer is really thin,” says Bin Ma, an astronomer at the Chinese Academy of Sciences in Beijing, “so it is possible to put a telescope above.”

Ma and colleagues took the first-ever measurements of nighttime atmospheric blur from the highest point in East Antarctica, called Dome A. From April to August 2019, instruments on an 8-meter-tall tower at China’s Kunlun research station tracked how Earth’s atmospheric turbulence distorted incoming starlight. A nearby weather station also monitored atmospheric conditions, such as temperature and wind speed. Using these observations, researchers characterized the boundary layer at Dome A and its effect on telescope observations.

The boundary layer was, on average, about 14 meters thick; as a result, the light sensors at the top of the 8-meter tower were completely free of boundary layer blur only about one-third of the time. But when these instruments were above the layer, atmospheric interference was so low that a telescope could pick out details on the sky 0.31 arc seconds across, on average. The best recorded atmospheric conditions would let a telescope see features as small as 0.13 arc seconds.

“One-tenth of an arc second is extremely good,” says Marc Sarazin, an applied physicist at the European Southern Observatory in Munich who was not involved in the work. This is “really something you rarely achieve in Chile or on Mauna Kea” in Hawaii.

Researchers have found similarly excellent visibility above the boundary layer at another spot on the Antarctic Plateau, known as Dome C. But the boundary layer there is around 30 meters thick — making it more difficult to build an observatory above it. An optical telescope planned for construction on a 15-meter tower at Kunlun could take advantage of Dome A’s stellar views above the boundary layer, Ma says. Such crisp telescope images could help astronomers study a range of celestial objects, from solar system bodies to distant galaxies.

A South American mouse is the world’s highest-dwelling mammal

Wed, 29 Jul 2020 12:00:00 GMT

A yellow-rumped leaf-eared mouse has shattered the world record as the highest-dwelling mammal yet documented.

The mouse (Phyllotis xanthopygus rupestris) was found 6,739 meters, or 22,110 feet, above sea level on the summit of Volcán Llullaillaco, a dormant volcano on the border of Chile and Argentina. For comparison, Mount Everest is 8,848 meters high (29,029 feet).

The record was previously held by the large-eared pika (Ochotona macrotis), reported at an altitude of 6,130 meters during a 1921 Mount Everest expedition. Birds have been found at even higher altitudes (SN: 2/13/14).

That mammals can live at these heights is astonishing, considering there’s only about 44 percent of the oxygen available at sea level. “It’s very difficult to sustain any kind of physical activity, or mental activity for that matter,” says Jay Storz, an evolutionary biologist at the University of Nebraska–Lincoln. The temperature is also rarely above freezing and can drop as low as –60° Celsius.

Storz and colleagues captured several yellow-rumped leaf-eared mice, including the summit-topping one, plus mice from three other species from a range of high altitudes, the team reports July 16 in Proceedings of the National Academy of Sciences. Next, the team plans to look for genetic changes that might have equipped these animals to survive at high elevations. Surprisingly, another yellow-rumped leaf-eared mouse was found at sea level, indicating that this species has the broadest altitude distribution of any mammal, in addition to the altitude record.

Researchers captured a yellow-rumped leaf-eared mouse (Phyllotis xanthopygus rupestris) at a record altitude of 6,739 meters, or 22,100 feet, above sea level. Jay Storz, an evolutionary biologist at the University of Nebraska–Lincoln, and mountaineer Mario Pérez Mamani discovered the animal at the summit of Volcán Llullaillaco, a dormant volcano on the border of Chile and Argentina.

“It’s so amazing that they’re up there,” says Graham Scott, a physiologist at McMaster University in Hamilton, Canada who was not involved in the study. Understanding how these and other animals survive under low-oxygen conditions could provide insight into how humans could overcome diseases that cause reduced oxygen levels, he says.

To rehearse Perseverance’s mission, scientists pretended to be a Mars rover

Wed, 29 Jul 2020 10:00:00 GMT

Megan Barrington watched the sun rise over the rocky outcrop. When light struck at exactly the right angle, she mounted a gizmo that looked like eye exam equipment on a tripod and aimed it at the spot. The goal: gather evidence that this windswept wilderness once teemed with life, and then beam the information to her colleagues back home.

Soon, a version of that setup (minus Barrington) will be deployed on Mars. The state-of-the-art, zoomable, multispectral camera is part of the toolkit on NASA’s Perseverance rover (SN: 7/28/20). “That instrument is going to allow me to look at the mineralogy of Mars at Jezero crater,” the rover’s landing spot, says Barrington, a planetary scientist at Cornell University.

The rover is scheduled to launch to Mars on July 30. A February role-playing exercise in the Nevada desert by Barrington and six colleagues was a kind of dress rehearsal for the rover’s various instruments. Another 150 team members around the world played the “Earth” team during those two weeks, sending commands from remote mission control and receiving data as it would appear coming from the real rover.

“We’re not just simulating a Mars mission,” says engineer Raymond Francis of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who organized and led the trip. “We’re simulating a specific Mars mission by presenting data … to the people who designed the instrument that will take that data. So the standard is high not to look like clowns.”

Perseverance has the most demanding and ambitious to-do list of any rover yet: seek signs of past Martian life, prepare the way for future human missions and collect at least 20 samples of Martian rock for eventual return to Earth. And that’s just in its first two years. For contrast, Curiosity rover has drilled a few dozen holes over eight years on Mars, and didn’t store any of those samples for later (SN: 7/7/18, p. 8).

The dress rehearsal in the desert will help ensure that when Perseverance lands on the Red Planet in February 2021, its handlers on Earth can get straight to the science.

“We don’t want to get there and learn how to explore Mars while on Mars,” Francis says. “We want [team members] to be ready when the rover hits the ground.”

Water marks the spot

The first order of business was to find the right spot for the dry run. “We had to pick a site that kind of looked like Mars,” Francis says. “The parking lot would not do.” The team wanted the site to look as Mars-like as possible, no factories, footprints or foliage to break the illusion.

An ideal site would have geology that echoed Jezero crater, which is thought to be the remnants of an ancient lakebed and river delta (SN: 11/19/18). It also had to be within a few hours’ drive of JPL, and not totally off the grid — the rover team slept in hotels, ate dinner in restaurants and had reliable Wi-Fi to send data to the Earth team every night.

The final requirement was that it be someplace the Earth team hadn’t seen before. If mission control members recognized the site, they could bias their findings with what they already knew.

Engineer and team leader Raymond Francis gets up close with the rocks to make a measurement.JPL-Caltech/NASA

“Most of the popular Mars analogs are already well known to the Mars community,” Francis says. “So we had to be a little sneaky.”

Previous exercises, in November 2017 and February 2019, were run in the Mojave Desert in California. For 2020, the rover team headed to Walker Lake in western Nevada. The lake’s water has been receding for a thousand years, so there are spots near the ancient shoreline where the present-day lake is invisible.

Walker Lake’s rocks preserved a cornucopia of biological signals for the ground team to discover: fossilized fish bones and shells of tiny shrimplike crustaceans called ostracods, which are not expected on Mars; and microbial fossils called stromatolites, which could plausibly be found in Jezero crater (SN: 10/17/18).

Toolkit

Francis and his team brought handheld versions of almost all the rover’s instruments to gather whatever data the Earth team requested. They had a drill, handheld spectrometers, lasers, a ground-penetrating radar that they transported in a jogging stroller, plus several elaborate camera setups to represent the rover’s navigation, hazard avoidance and zoomable 3-D science cameras.

Perhaps the most important piece of equipment was the broom used for sweeping away footprints. It became a running joke, Francis says: “We’ve got all this equipment, a multibillion-dollar mission, and it’s all hinging on this 99-cent broom.”

Almost everything went smoothly. But a few days into the mission, Barrington’s zoomable camera had “a major malfunction,” she says. She framed her shot, and…. nothing happened. The camera wasn’t getting any power, she realized. “I took it apart and rewired many pieces, to no avail,” she says.

She and her teammates finally realized one of the power adapters had completely blown. She had to drive two hours to the nearest city to get a new one.

Of course, driving into town to get a new part won’t be an option on Mars. The real camera, called Mastcam-Z, has been through weeks of rigorous testing and calibration, and is probably up to the task. But “we all go into missions knowing that sometimes irreversible mistakes occur,” Barrington admits. “All we can do at that point is use the instruments to the fullest capacity of which they are capable of operating.”

Planetary scientist Megan Barrington adjusts her instrument, a multispectral, zoomable camera standing in for Perseverance’s Mastcam-Z.JPL-Caltech/NASA

Signs of life, big and small

There was one major giveaway that the team was actually on Earth. “This is very much middle-of-nowhere desert, which is good,” Francis says. But the rover site was mere steps from a U.S. Department of Defense munitions facility, one of the largest in the world.

“It was really something to behold,” Barrington says. “They had hundreds of bunkers lined up in rows as far as you could see…. All of that was one very crooked metal fence away from us.”

More than once, military police showed up to check the team’s credentials. “I had to approach them and say, hello, people with the guns, I need you to stop walking now,” Francis says. “We’re running a Mars rover simulation and we don’t want you to put your footprints in this sand.”

Despite Francis and colleagues’ best efforts, the bunkers showed up in a few photos. The ground team gamely ignored them, apart from a few jokes about SpaceX founder Elon Musk building a Martian city.

By the end of the two-week exercise, the remote science team reviewing the data had noticed the ostracods and fishbones, and started exploring the stromatolites. “They were doing a good job of finding the biomarkers,” Francis says, who now has hope that “if Mars is hiding stromatolites, maybe we’ll see them.”

Coming home to quarantine

The field trip ended on February 27, just as awareness of the novel coronavirus SARS-CoV-2 was rising in the United States. By March 15, JPL told employees to work from home. “We only had a few days together before we were all on remote work,” Francis says.

The pandemic has already contributed to the delay of the launch of the European and Russian ExoMars rover, which was also supposed to launch in July (SN: 3/12/20). If Perseverance misses the late July to early August launch window, the rover can’t head to Mars until 2022.

If the pandemic is still an issue by the time the rover lands in February, Francis doesn’t know what the team will do. “But,” he says, “the good news is the mission is designed for remote operations.”

Close relatives of the coronavirus may have been in bats for decades

Tue, 28 Jul 2020 21:21:01 GMT

Viruses from the coronavirus lineage responsible for COVID-19 have been circulating in bats for decades, long before the virus started infecting people last year, a new study suggests.

How exactly the virus jumped to humans is still a mystery. But the study suggests the coronavirus most likely evolved in bats — such as intermediate horseshoe bats (Rhinolophus affinis), the source of the coronavirus that caused the 2003–2004 SARS outbreak — not snakes or pangolins as some researchers have suggested (SN: 1/24/20). Pangolins or another animal might still have been an intermediate host before the virus made it to humans.

Maciej Boni, an epidemiologist at Penn State, and his colleagues examined the genetic blueprints of the new coronavirus, or SARS-CoV-2, and 67 related viruses. The analysis aimed to uncover the evolutionary history of SARS-CoV-2 and see if the virus had exchanged bits of genetic material with other coronaviruses, a process called recombination, to become the formidable pathogen it is now.

SARS-CoV-2 is not the result of genetic shuffling among known coronaviruses, the researchers report July 28 in Nature Microbiology. Previous studies had suggested that recombination with coronaviruses from pangolins may have contributed a portion of the virus’ spike protein, which is used to break into human cells (SN: 3/26/20). But the spike’s ability to attach to a protein on host cells called ACE2, which allows the virus to gain entry, appears to be an ancestral trait, rather than one gained from recombination.

Based on the evolutionary relationship among the 68 coronaviruses, the researchers estimate that the branch of the virus family tree that leads to SARS-CoV-2 diverged from related viruses between 1948 and 1982. Those dates suggest that the coronavirus lineage that gave rise to the virus behind the pandemic has been present in bats for decades.

That long period hints that more bat viruses with the potential to infect humans are circulating in horseshoe bats. Searching for such bat viruses can help identify potential threats before the pathogens make the jump, the team writes.

These ancient seafloor microbes woke up after over 100 million years

Tue, 28 Jul 2020 15:00:00 GMT

Even after 100 million years buried in the seafloor, some microbes can wake up. And they’re hungry.

An analysis of seafloor sediments dating from 13 million to nearly 102 million years ago found that nearly all of the microbes in the sediments were only dormant, not dead. When given food, even the most ancient microbes revived themselves and multiplied, researchers report July 28 in Nature Communications.

Scientists have pondered how long energy-starved microbes might survive within the seafloor. That such ancient microbes can still be metabolically active, the researchers say, just goes to show that scientists are still fathoming the most extreme limits to life on Earth.

The microbes’ patch of seafloor lies beneath a kind of ocean desert, part of a vast abyssal plain about 3,700 to 5,700 meters below sea level. Researchers, led by microbiologist Yuki Morono of the Japan Agency for Marine-Earth Science and Technology in Kochi, examined sediments collected in 2010 from part of the abyssal plain beneath the South Pacific Gyre. That region of the Pacific Ocean contains few nutrients that might fuel phytoplankton blooms and thereby support a cascade of ocean life. As a result, very little organic matter makes its way down through the water to settle on the seafloor.

The extremely slow accumulation of organic material and other sediments in this region does allow oxygen in the water to seep deep into the sediments. So Morono and colleagues wondered whether any aerobic, or oxygen-liking, microbes found there might be revivable. After “feeding” microbes from the collected sediments with nutrients including carbon and nitrogen, the team tracked the organisms’ activity based on what was consumed.

The aerobic microbes in the sediments turned out to be a highly diverse group, consisting mostly of different types of bacteria belonging to large groups such as Alphaproteobacteria and Gammaproteobacteria (SN: 9/14/17). Nearly all the microbes responded quickly to the food. By 68 days after the experiment’s start, the total number of microbial cells had increased by four orders of magnitude, from as little as about 100 cells per cubic centimeter to 1 million cells per cubic centimeter.

Those increases weren’t just among the youngest microbes. Even in the sediment sample containing the most elderly — about 101.5 million years old — up to 99.1 percent of the microbes were revived.