A new squishy robot could keep hearts from skipping a beat.

A silicone sleeve slipped over pigs’ hearts helped pump blood when the hearts failed, researchers report January 18 in Science Translational Medicine. If the sleeve works in humans, it could potentially keep weak hearts pumping, and buy time for patients waiting for a transplant.

To make the device contract, biomedical engineer Ellen Roche and colleagues lined it with two sets of narrow tubes. One set encircles the sleeve, like bracelets; the other runs from top to bottom. When air pumps through the tubes, the sleeve compresses (like a clenched fist) and twists (like wrung-out laundry). Those actions mimic how the layers of the heart contract.
Researchers programmed the sleeve to sync with the heart’s motion. And like a healthy heart, the robot sleeve’s double squeeze gets blood moving.

Roche’s team, which did the work while she was at Harvard University, triggered heart failure in six pigs and then measured the volume of blood pumped by the heart with and without the sleeve’s help. Heart failure cut the volume roughly in half, to about 1 liter of blood per minute. But the sleeve restored the pumped volume to about 2½ liters per minute — just about normal, Roche, now at National University of Ireland, Galway, and colleagues report.

An analysis of nearly 400 kinds of tomatoes suggests which flavor compounds could bring heirloom deliciousness back to varieties that were bred for toughness over taste.

About 30 compounds are important in creating a full-bodied tomato flavor, says study coauthor Harry Klee of the University of Florida in Gainesville. He and colleagues have identified 13 important molecules that have dwindled away in many mass-market varieties. Some of the flavor compounds deliver such a thrill to the human sensory system that even a modest increase could make a big difference, the researchers report January 26 in Science.
“I think this will definitely help,” says Alisdair Fernie, who was not part of the study but has studied tomato chemistry at the Max Planck Institute of Molecular Plant Physiology in Potsdam, Germany. “Taste is incredibly complex,” he says, so creating more appealing commercial varieties “for certain, requires a holistic approach,” he says.

To achieve that holistic view, the researchers teamed up with geneticists at China’s Agricultural Genomics Institute in Shenzhen, who determined the full genetic makeup of a whopping 398 kinds of tomatoes, wild as well as heirloom and commercial. The scientists ran 96 varieties of tomatoes through taste-testing panels, looking for genetic and chemical similarities among those varieties ranked tastiest.

Much of what makes some tomatoes taste better is actually smell, Klee points out. Tongues can detect relatively few qualities, such as sweetness, acidity and softness. Chemical detectors in the nasal passages are far more varied and sensitive. So what really puts the “Mmmm” into a tomato is the whoosh of air forced up into the nasal passages as someone swallows. Airborne compounds, known as volatiles, are abundant in tomatoes, and Klee looks to them for flavor magic.

Of these volatile compounds, some appear in even the tastiest tomatoes at minuscule levels — only parts per trillion. But human senses respond so strongly to the odors that a little bit goes a long way. Tomatoes should taste noticeably better if researchers can breed just four or five heirloom versions of volatile-producing genes back into commercial varieties, Klee says.

Increasing the sweetness of today’s tomatoes, on the other hand, may be tougher. About 80 percent of the sugar in commercial tomatoes comes from the leaves and is transferred to the big red globes as they mature (SN: 7/28/12, p. 18). Because breeders have done such a great job of maximizing the number of fruits on a plant, the plants would need lots of leaves to sweeten them all. So the price of sweeter tomatoes would be making them smaller, and fewer.
“Now we come to the real crux of the problem,” Klee says. “I have to fix the flavor, but I can’t compromise all of the stuff that breeders have done to the modern tomatoes to make them healthier, more productive, more disease resistant and more shippable,” he says.

And let’s not forget about what happens to tomatoes after they’re picked, says Ann Powell, who studied tomato ripening and disease resistance at the University of California, Davis and is now at the National Science Foundation. Cooling weakens flavor, as cooks who shriek at the horror of storing tomatoes in refrigerators have long known. Therefore, Powell says, another study of Klee’s from 2016 — on how chilling can turn on and off genes — makes an important companion to the new work. A combination of breeding better plants and coddling them strategically may be the way forward for tastier tomatoes.

In a remote corner of eastern Russia, where long winters bring temperatures that rarely flicker above freezing, the genetic legacy of ancient hunter-gatherers endures.

DNA from the 7,700-year-old remains of two women is surprisingly similar to that of people living in that area today, researchers report February 1 in Science Advances. That finding suggests that at least some people in East Asia haven’t changed much over the last 8,000 years or so — a time when other parts of the world saw waves of migrants settle in.
“The continuity is remarkable,” says paleogeneticist Carles Lalueza-Fox of the Institute of Evolutionary Biology in Barcelona, who was not involved with the work. “It’s a big contrast to what has been found in Europe.”

In Western Europe especially, scientists studying ancient DNA have put together a picture of flux, says study coauthor Andrea Manica. “Every few thousand years, there are major turnovers of people.” Around 8,000 years ago, he says, migrating farmers replaced hunter-gatherers in the area. And a few thousand years after that, Bronze Age migrants from Central Asia swept in.

In DNA collected from the bones and teeth of these ancient peoples, scientists can spot genetic signatures of different populations. When a population of farmers balloons, Lalueza-Fox says, the signatures of hunter-gatherers are mostly erased.

But whether that’s true across the globe is unclear, says Manica, of the University of Cambridge. “We wanted to see what happened in other places…. Asia is huge compared to Europe, and it’s been neglected.”
Manica’s team collected DNA from the skeletons of five ancient people found in a cave called Devil’s Gate. The cave rests in a far east finger of Russia, tucked along the border of China and North Korea, and holds human remains, scraps of textiles and bits of broken pottery.

Researchers gathered enough DNA from two of the people to piece together about 6 percent of the genome, the complete set of genetic instructions inside a cell’s nucleus. That’s not much, Manica says, but it’s enough to compare the Devil’s Gate denizens with other people. The researchers analyzed the genomes of people strewn across the far reaches of the continent — from the Dolgan in Siberia to the Thai thousands of kilometers south.

Genetically, the 7,700-year-old women closely resembled the Ulchi, a small group of hunter-fishers who still live off the land today. Manica can’t say whether the Ulchi are direct descendants of the two Devil’s Gate women, or just closely related. But the find suggests a pocket of stability in East Asia — a place where hunter-gatherers weren’t swept out by, or folded into, booming groups of farmers.

Perhaps farming didn’t take off there because the cold climate wasn’t good for growing crops, Manica says. Or maybe the ideas and technologies from farmers and other migrants made it to the Ulchi without an accompanying influx of people. (The Ulchi aren’t like primitive hunter-gatherers of the past. They farm a bit, and have adopted new ways to fish, hunt and store food, he points out.)

“This shows that ideas can travel without people moving with them,” Manica says.

That makes sense, Lalueza-Fox says. But scientists now need more data — additional samples from East Asia, and Southeast Asia, too, he says. “I have a feeling the whole story will be much more complicated.”

To some forest creatures, a tree is a home. To scientists, it’s a beacon. A new way of mapping forests from the air by measuring chemical signatures of the tree canopy is revealing previously unrecognized biodiversity.

The swath of tropical forest covering the Peruvian Andes Mountains and the Amazon basin is one of the most biodiverse places on Earth. But it’s such a wild and remote region that variation within the forest is hard to spot.
“If you look in Google Earth, it just looks like a big green blanket,” says study coauthor Greg Asner, an ecologist at the Carnegie Institution for Science in Stanford, Calif.

Up close, it’s a different story. Each tree species has a distinctive set of chemical traits, such as levels of nutrients like nitrogen and phosphorus in the leaves. Collectively, those characteristics can reveal a lot about the makeup of the forest.
To peek beneath the green blanket, Asner and colleagues divided 76 million hectares of forest into 100-kilometer squares. The researchers measured levels of water, nitrogen, phosphorus and calcium in the trees’ leaves via aircraft by measuring the wavelengths of light reflected by the forest canopy, taking samples from small areas of each square. They also mapped leaf levels of lignins and polyphenols, two chemicals used for defense. Using that data, the scientists identified 36 unique types of forest — a much more nuanced view than the broad categories currently used for classification, the researchers report January 27 in Science. They parceled those highly specific forest types into six groups that roughly aligned with the country’s topography and geography.
Parsing out these differences in forests at such a fine scale is important for guiding conservation efforts, Asner says. A particular spot might appear at a distance to be the same as its surroundings but may actually contain species found nowhere else.

The team is now carrying out similar studies in northern Borneo and Ecuador. Eventually the researchers hope to boost their sensors into orbit to map biodiversity around the globe.