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| 23 July 2026 | | Today’s SciencePrudence details a tense exchange between a U.S. Representative and the head of the White House Office of Science and Technology Policy. But first, catch up on the latest science news, including a new kind of breathalyzer and some avocados that are delightfully different. | |
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| Cancer | News from Science | | The darkness that spreads | Something strange lurks in the depths of Vermont’s Lake Memphremagog: an inky-black cancer that afflicts nearly one-third of its abundant brown bullhead catfish. In a study in Nature, researchers show that unlike most cancers, this one—a melanoma—is not an abnormal growth of each fish’s own tissue. Instead, it appears to be a single cancer that has somehow spread from fish to fish: a giant malignant clone.
What the researchers are calling brown bullhead melanoma joins only a handful of other known transmissible cancers, such as a ghastly face-eating tumor in Tasmanian devils. It’s the first such cancer to be found in a fish, and it brings a host of mysteries, including when and where it originated, how it spreads, and why the catfish are susceptible.
When anglers began reporting the cancerous catfish in 2012, alarmed locals suspected a pollutant. But DNA points to a different cause, according to data scientist Julie Dragon, senior author of the study. The team analyzed variations in mitochondrial and nuclear DNA from cancerous and healthy tissue in the catfish. Typical cancers are more closely related to their host than to tumors in other individuals. But in this case, Dragon said, “all the tumors clustered together, and all the hosts clustered together .” The unexpected pattern pointed to a single, separate origin for the cancer, as if it was a distinct organism that had colonized the fish.
The cancer is now turning up in other lakes in New England and Canada. And it may have a long pedigree: In 1858, writer Henry David Thoreau described a brown bullhead “covered with an inky-black kind of leprosy” that sounds very like the disease ravaging catfish today. | | |
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| Medical Technology | Device | | Breathing the burn |  | | A user measures breath acetone with a smartphone-assisted detector. Alivion AG | During a traffic stop, if a police officer suspects that a driver has been drinking, they might ask them to blow into a breathalyzer. In a new study, scientists present a similar device: Instead of determining blood alcohol content, however, this handheld machine sniffs out when a person’s body is burning fat.
The detector works by sensing acetone, a molecule released into the breath when the body shifts from using carbohydrates to fat as fuel—a metabolic state known as ketosis. While doctors have long used breath acetone as a measure of metabolism, testing it usually involves bulky laboratory equipment. Researchers used the new device to analyze more than 312 breath samples from 12 healthy volunteers, finding that it detected acetone almost as accurately as a high-precision mass spectrometer, all while relying on a single exhalation.
The device is paired with a smartphone app, which coaches users on proper breathing technique, allowing them to monitor their metabolism in real time. While many people may be interested in tracking breath acetone levels to aid in weight loss or increase athletic performance, the technology could also be of particular value for individuals with certain kinds of drug-resistant epilepsy, which is often treated with a ketogenic diet traditionally monitored with repeated finger-prick blood tests. “ We’re really moving toward healthcare solutions that, in the future, you won’t need to go to the hospital for anymore,” senior author Andreas Güntner said in a statement. “You’ll be able to do them at home.” | | |
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| Agricultural Genetics | PLANTS, PEOPLE, PLANET | | These avocados aren’t like the others | Chances are the guacamole you bought from the grocery store the other day was made of mashed up clones. Of the 11 million metric tons of avocados grown around the world in 2024, more than 80% belonged to a variety known as the Hass avocado, which are cultivated through a process called clonal grafting. Because these fruits are genetically identical, the same threat—a single pathogen, for example—could obliterate entire populations in one fell swoop.
But the varieties that grow in the humid lowlands of Central America aren’t your typical supermarket avocados. “They’re bigger, brighter and smoother,” archaeobotanist Kevin Wann, who had never eaten an avocado before embarking on a project to study the plants, told Smithsonian Magazine . Hass and his colleagues examined DNA from avocado leaves collected in Nicaragua, Honduras, and southern Mexico, also interviewing local gardeners and rural farmers to learn more about the region’s trees. The team uncovered genetic evidence that, roughly 5000 years ago, people carried large avocado seeds with them as they migrated north out of South America. These plants hybridized with local varieties, eventually producing the hotbed of diversity found in the region today.
“There is a much wider breadth of avocado diversity that science had not yet documented,” Wann said in a statement. “We could potentially tap into this genetic diversity to conserve commercial avocado plants that are vulnerable to disease.” | | |
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| | | | Take Action with the Union of Concerned Scientists’ (UCS) Science Network | | Use your expertise to advance science for the public good. Receive specialized trainings, gain resources for science advocacy, and more—designed for experts like you—and be part of UCS’ Science Rising initiative to protect science and democracy. | |
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| | | SciencePrudence |  | | Michael Kratsios, science adviser to President Donald Trump, testifying before Congress on the administration’s research priorities. REUTERS/Eric Lee | | Congressional duel ends in standoff | | Jeffrey Mervis, Senior Correspondent, News from Science | Representative George Whitesides (D–CA) is pretty sure that someone in the White House Office of Science and Technology Policy (OSTP) is screening pending grants from the National Science Foundation (NSF) to make sure they align with the policies of the Trump administration. But he doesn’t have any proof. And yesterday, when Whitesides tried during a congressional hearing to get confirmation from the head of that office, he got nowhere.
“I am not personally involved in any NSF grant decisions,” Michael Kratsios, who also serves as the president’s science advisor, told Whitesides after the legislator asked him if anyone at OSTP was involved.
“That’s not an answer to what I asked,” Whitesides retorted.
But Kratsios’s second response—“I’m not aware of anyone at OSTP who is working on individual NSF grant proposals, and I wouldn’t condone that”—didn’t come any closer to satisfying Whitesides. Kratsios also rebuffed Whitesides’s follow-up question about whether OSTP was engaged in any “grouping of grant decisions” by saying, “I don’t know what that means.”
Speaking to ScienceAdviser after the hearing, Whitesides acknowledged his frustration with Kratsios, who was the sole witness at a hearing on Trump’s current budget request for U.S. research agencies before the House science committee. “I pressed him on it,” Whitesides said, “and I thought that he was trying to be tricky with his answers.”
“Several reliable sources” have told him that such vetting is taking place, Whitesides added. “OSTP isn’t that big, so the idea that he wouldn’t know about it is just not believable. But I don’t have a name.” | |
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| A heart with a brain | | Every heartbeat requires the careful coordination of the organ’s muscles. This essential management is carried out by a minibrain of sorts within the tissue: the intrinsic cardiac nervous system. Now, researchers are teasing apart the different kinds of neurons that keep the blood pumping. “In the last few years, we’ve really come to appreciate—and this just puts that on steroids—that these peripheral outposts of the nervous system are doing a lot more than just receiving a signal from the brain and passing it on,” one expert said. | | Cell Paper | Read more at Nature | |
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| Exploding the sun | | Orcas are sometimes called killer whales, and they’ve more than earned the moniker. They display a diversity of intelligent hunting tactics to catch different types of prey. But none are as explosive as what researchers observed in the Gulf of California: ramming sunfish so hard they literally burst. “It’s a hunting tactic, but that involves a play game in the process,” one marine biologist noted. | | Frontiers in Ethology Paper | Read more at New Scientist | |
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| That’s no moon—or is it? | | In a galaxy far, far away—specifically a system known as CD-35 2722—exists an astronomical body that has scientists at a loss for words. The object is about as massive as Jupiter, but it orbits a brown dwarf, which in turn orbits a small star. So, it sort of acts like a moon, but moons orbit planets, not failed stars. “The structure of CD-35 is so different from the structure of the solar system that all the words we invented to describe the solar system just aren’t really working anymore,” one expert said. | | Nature Paper | Read more at Science News | |
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| | Papers are typically written as cautious confirmations … This style is designed to reflect new findings back to the writers’ home community. But it also slows scientific progress. | | Expert Voices | 16 July 2026 | James Evans, Casey Petroff, and Gary King | |
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| Last but not least | | Much like Arthur Dent, I never could get the hang of Thursdays. So, to keep my spirits up, I started today by watching another video of Jimothy. As one Seattle City Council member put it, “he’s an example to all of us that you don’t have to be perfect to be loved, and it’s what makes us different that makes us sensational.” |  | Christie Wilcox, Editor, ScienceAdviser
With contributions from Tim Appenzeller and Phie Jacobs
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