Enceladus’s Alien Ocean, Ancient Fungi and the Flavor of Influenza
Saturn’s moon Enceladus shows signs of life-supporting chemistry, fungi may have shaped Earth before plants, and repeat COVID infections raise long-term health risks for kids.
An artist’s impression of surface of Enceladus.
Tobias Roetsch/Future Publishing via Getty Images
Rachel Feltman: Happy Monday, listeners! For Scientific American’s Science Quickly, I’m Rachel Feltman. Let’s kick off the week with a quick roundup of some science news you may have missed.
First, some exciting space news. According to a study published last Wednesday in Nature Astronomy, the ocean of Saturn’s moon Enceladus contains complex organic molecules that indicate the environment could potentially support life.
Enceladus is a moon about as wide across as the state of Arizona. Back in 2005 the Cassini spacecraft caught plumes of water vapor and frozen particles shooting up from tiger-stripe-like fissures in the planet’s icy crust. Subsequent analysis of gravity measurements captured by Cassini confirmed the presence of a subsurface ocean near the moon’s south pole about a decade later.
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Cassini’s mission ended in 2017, but new analysis of data from a 2008 flyby just yielded additional insights into the frosty moon’s watery reservoir. In flying through one of Enceladus’s water plumes the spacecraft exposed its Cosmic Dust Analyzer instrument to tiny, freshly ejected grains of ice.
After years of studying data from different flyby events to understand how Cassini’s instruments behaved under different conditions, scientists were able to apply their findings to old data and find new patterns.
The new study determined that several sophisticated carbon-based structures, including esters and ethers, can be found in the subsurface waters of Enceledus. That’s important because these structures are identical to substances considered to be vital chemical building blocks for living organisms on Earth. And that adds to evidence the moon could be a compelling candidate for hosting some kind of life—or at least allowing us to gain a better understanding of how life evolved on our own planet.
Speaking of life as we know it—and how the heck it got here—a study published last Wednesday in Nature Ecology & Evolution suggests that for hundreds of millions of years before plant life made it onto land, fungi may have dominated the planet.
The delicate filaments of mycelium that typically make up the bodies of fungi don’t tend to fossilize well, and the fossils they do leave behind are often microscopic and hard to identify. This new study aimed to overcome that issue with the help of a “molecular clock.” Essentially, scientists can plot out the timeline of one species’s divergence from another by tallying up the difference in their respective numbers of genetic mutations, which happen at fairly regular intervals as organisms evolve.
Counting the ticks of a molecular clock is only possible if you have regular anchor points from the fossil record to calibrate them, which is tricky for fungi. The researchers behind the new study got around that by integrating instances of horizontal gene transfer between species, along with mutations passed down from one generation to the next. Tracking when a gene moved from one lineage to another helped the scientists pinpoint which organisms emerged when, which they say has allowed them to tighten up the timeline of fungal evolution. The study suggests that fungi evolved from a common ancestor dating back to roughly 1.4 to 0.9 billion years ago, which is about half a billion years or more before land plants evolved. The researchers argue that fungi may have paved the way for plants by breaking down rocks and cycling nutrients to create the first soils.
Now for some health news. According to a study published last week in the Lancet Infectious Diseases, the risk of children and young adults developing long COVID could be twice as high with a second infection than with the first. Looking at 2022 and 2023 data from about 465,000 children and adolescents , the researchers found an increased risk of chronic symptoms potentially related to the condition such as severe fatigue, headaches, kidney damage, abdominal pain, cognitive issues and abnormal heartbeats after a second COVID infection. Blood clots were more than twice as likely with a repeat COVID case, and the risk of myocarditis—a potentially lethal swelling of the heart—actually more than tripled. The study authors noted that long COVID cases weren’t necessarily linked to severe illness during the acute COVID infection. The researchers argue that this highlights the need for ongoing immunization of young people.
In some lighter respiratory infection news a study published last Wednesday in ACS Central Science hints that we might one day have access to an easy, surprisingly tasty method of diagnosing the flu at home. The researchers behind the new study have reportedly created a molecular sensor that reacts to the presence of flu virus by producing a distinct flavor.
The sensor responds to neuraminidase, which is a glycoprotein that the influenza virus uses to infect cells. The synthesized substance used in the sensor is attached to a molecule of thymol, which is found in the herb thyme and produces a strong taste. In lab tests using vials of human saliva the presence of influenza caused the thymol to break off on its own. In a human mouth that reaction should lead to a distinct herbal flavor. The researchers say they hope to conduct human clinical trials of a flu test in roughly the next couple of years.
Speaking of surprisingly delicious things, a study published last Friday in iScience shows how a traditional recipe for yogurt used a rather unusual secret ingredient to kick-start fermentation: ants.
Yogurt forms when microorganisms ferment milk and create lactic acid, which thickens the dairy and gives it a tangy taste. In the early 20th century scientists isolated some of the bacterial strains capable of accomplishing this, and now yogurt production largely relies on just a couple species of bacteria.
A lot of traditional yogurt-making methods fell by the wayside as production became standardized, including a traditional practice from the Balkans and Turkey involving red wood ants. The authors behind the new study decided to take a closer look at that recipe.
Under the guidance of the Bulgarian family of one of the study’s co-authors, along with other locals, the researchers placed four ants into a vessel of warm milk and covered the jar with a piece of cheesecloth. The researchers then buried it in an ant mound overnight, where the heat produced by the colony’s activity served as an incubator for fermentation. By the next day the sample showed early signs of fermentation, with the milk coagulating, becoming more acidic and taking on a slightly sour taste.
Back in the lab the team confirmed that the red wood ants carry lactic and acetic acid bacteria, including a type similar to one found in commercial sourdough. The scientists also found that the formic acid ants produce as a defense mechanism serves to acidify the milk and , probably helps create a better environment for the microbes.
The researchers even partnered with chefs from a two-star Michelin restaurant to create dishes such as ant-powered ice cream and soft cheese. But don’t go digging around in your backyard to find fermentation buddies just yet: the scientists do warn that live ants can carry parasites, while frozen or dehydrated ants come with their own potential risks. That can add an element of danger to the process if you don’t have the right equipment and knowledge to confirm the yogurt is safe to consume.
That’s all for this week’s science news roundup. Tune in on Wednesday to hear how one of the Internet’s most famous astronauts is using his experience in spaceflight to write alternate-history thrillers.
Science Quickly is produced by me, Rachel Feltman, along with Fonda Mwangi and Jeff DelViscio. This episode was edited by Alex Sugiura. Shayna Posses and Aaron Shattuck fact-check our show. Our theme music was composed by Dominic Smith. Subscribe to Scientific American for more up-to-date and in-depth science news.
For Scientific American, this is Rachel Feltman. Have a great week!
