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Scientists have traced the sensation of itch to a place you can’t scratch.

The discomfort of a mosquito bite or an allergic reaction activates itch-sensitive nerve cells in the spinal cord. Those neurons talk to a structure near the base of the brain called the parabrachial nucleus, researchers report in the Aug. 18 Science. It’s a region that’s known to receive information about other sensations, such as pain and taste.

The discovery gets researchers one step closer to finding out where itch signals ultimately end up. “The parabrachial nucleus is just the first relay center for [itch signals] going into the brain,” says study coauthor Yan-Gang Sun, a neuroscientist at the Chinese Academy of Sciences in Shanghai.
Understanding the way these signals are processed by the brain could someday provide relief for people with chronic itch, Sun says. While the temporary itchiness of a bug bite is annoying, longer term, “uncontrollable scratching behavior can cause serious skin damage.”

Previous studies have looked at the way an itch registers on the skin or how neurons convey those sensations to the spinal cord. But how those signals travel to the brain has been a trickier question, and this research is a “major step” toward answering it, says Zhou-Feng Chen, director of the Center for the Study of Itch at Washington University School of Medicine in St. Louis.

A network of neurons in the spinal cord wrangles itch signals, previous research suggests. In particular, spinal neurons that make a protein called gastrin-releasing peptide receptor have been shown to be important in itch signaling. But those neurons didn’t link up directly to the parabrachial nucleus, or PBN, Sun’s team found; instead, they talked to other neurons that send messages to the PBN.

When mice were given injections of a drug that induces allergic itching, the rodents showed greater activity in those neurons connecting the spinal cord to the PBN, Sun and colleagues found. In another experiment, the researchers made neurons going to the PBN light-sensitive, and then used light to stop those neurons from sending messages. When those nerve cells were blocked, mice given an itch-triggering drug scratched less.

It’s too soon to say whether itch signals in humans follow the same route — or whether all kinds of itches take the same path. An allergic itch is different from the sort of itch that comes from a light touch, and the two might be handled differently by the brain (SN: 11/22/08, p. 16). And mice, unlike humans, can’t actually describe how itchy they’re feeling. So scientists have to rely on clues like scratching, a reaction to an itch, not a direct measurement of the sensation itself. Which raises the question: If you don’t feel an urge to scratch an itch, is the itch really there at all?

We came. We saw. We earned our 2017 eclipse t-shirts.

For us, the Aug. 21 total solar eclipse was the culmination of weeks — nay, months — of planning the stories you’ve recently seen on Science News. And as the big day finally approached, many members of the Science News staff past and present traveled far and wide to experience the spectacle.

Undeterred by traffic and clouds, and fueled by bottomless fried chicken and moon pies, correspondents made their way to small towns and big cities in the path of totality. For many of us, this was our first total solar eclipse, and it lived up to the hype. Astronomy writer Lisa Grossman wrote from her perch on a mountaintop in Wyoming, “I thought I knew what to expect from my first total solar eclipse. I had no idea.”

Even the crew at the Science News offices in Washington, D.C., got a pretty sweet view of the moon blocking out 81 percent of the sun. And it has inspired many of us to start planning now for the total solar eclipse that will cross the United States in April 2024.

All in all, the 2017 eclipse was unlike anything we’ve seen before, and it’s something we’re not likely to forget. But just in case, the video below showcases some snapshots from our trips to totality and back again.

When nocturnal aardvarks start sunbathing, something’s wrong.

If the animals are desperate enough to bask like some cold, sluggish turtle, it’s because they’ve got the chills. Robyn Hetem, an ecophysiologist, has the body temperature data to prove it — collected from late 2012 into 2013, the hottest summer the arid Kalahari region in South Africa had seen in more than 30 years.

Hotter, drier conditions are predicted to become the norm for southern Africa as the climate changes. Now Hetem and colleagues have used that foretaste of change to show that higher temperatures might hammer the normally heat-tolerant aardvarks by shrinking the animals’ food supply.
Aardvarks live their burrow-digging lives just about anywhere in sub-Saharan Africa except the desert. The toothless night-foragers dine by slurping insect colonies. One of Hetem’s students at the University of the Witwatersrand in Johannesburg spent two years collecting hundreds of aardvark droppings and can confirm that Orycteropus afer in the Kalahari eat only termites and ants. Yet the solitary, long-snouted, knee-high mammals are more closely related to elephants than to any pointy-nosed South American anteater.

An aardvark looks “very lethargic but is incredibly strong and fast,” Hetem says. The researchers wanted to fit wild aardvarks with tracking devices and data loggers but first had to catch the animals. Nets failed. Traps failed. One cornered aardvark burst out of a burrow, knocked four men to the ground and then outran them.
Eventually, researchers placed instruments on six animals. When the Kalahari baked and good rains were months late, the aardvarks grew thin and bony. They started hunting during the day and sunbathing. The animals, once able to internally stabilize their body temperatures, started to have great plunging chills at night, according to data loggers. That’s a sign of starvation, Hetem says, and occurs when the body no longer has energy to warm itself. Five of the six tracked animals died, along with at least 11 other aardvarks in the neighborhood.
Aardvark heat tolerance wasn’t the problem. The animals were dying off because their food couldn’t take the heat and drought, Hetem and colleagues argue in the July Biology Letters. Hot, dry spells can make ant and termite colonies shrink and retreat to hard-to-reach hideouts.
Other African wildlife might suffer from a shortage of aardvarks, which are prodigious burrow diggers. In a Kalahari study, one aardvark used more than 100 burrows in two years. So many hideaways are a boon for others. Bat-eared foxes, warthogs, birds called ant-eating chats and at least two dozen other species pop into aardvark architecture, sometimes outright moving in. If aardvarks dwindle, shelter might grow scarcer for other animals.

“We kind of think of climate change as: Things are going to get hotter and species might be sensitive to it,” Hetem says. “There’s so much more we need to understand.”

DENVER — An invasive beetle has unexpected — and potentially troublesome — tastes in trees. Now two new studies are clarifying the insects’ dining habits, researchers reported at the annual Entomological Society of America meeting.

Metallic-green Asian beetles called emerald ash borers (Agrilus planipennis) have devastated wide swaths of forest in North America. For years, researchers believed that only various kinds of ash trees were at risk. But in 2014, researchers noticed infestations in white fringe trees (Chionanthus virginicus), a multi-stemmed tree native to the southeastern United States with flowers like a cluster of streamers. And after looking at trees related to ashes, researchers reported lab evidence in 2017 that the beetle larvae can grow to adulthood in the Manzanilla variety of commercial olive trees (Olea europaea). Whether the beetle poses a serious or slight risk to the overlooked targets is still being researched.
Emerald ash borers, accidentally imported probably in wood packing materials during the 1980s or 1990s, have killed hundreds of millions of ash trees in 31 states and two Canadian provinces. Larvae chewing tunnels through trees’ internal nutrient channels can doom a tree. It’s “a major, major pest,” says entomologist Jackie Hoban of the University of Maryland in College Park. “It’s so sad — you see entire patches of trees just dead.”
Lab tests of the recently discovered threat to olive trees show that adult borers don’t eat as much of these leaves as they do of ash leaves, forest entomologist Donnie Peterson of Wright State University in Dayton, Ohio, reported November 6 at the meeting. These adults also die prematurely if those leaves are the only food option. But adult borers’ distaste for this variety of olive doesn’t yet mean the trees are safe. Female beetles feeding on ash trees might, in theory, fly to a nearby olive to lay eggs.
To compare beetles’ preferences for laying eggs on olive versus ash will take a larger study. But Peterson’s first results are a little worrying. When he put olives and green ashes in a known infested zone, one of the few eggs he found was on an olive tree.

Free-flying beetles do lay eggs on white fringe trees, attacks that long went unreported. But the trees may not be as healthful a feeding site for beetle larvae as ash trees. In indoor tests, fewer larvae survived to their later stages on the fringe trees compared with larvae on white ashes, David Olson of the University of Kentucky in Lexington reported November 5.
Olson works on whether biocontrol strategies developed for ash trees might also work on white fringe trees. So far, it doesn’t look encouraging. In outdoor tests, the most successful of four tiny parasitic wasp species released in North America did what they’re supposed to: Tetrastichus planipennisi doomed some beetle larvae in ash trees by using the youngsters as living food for baby wasps. Beetle larvae in nearby fringe trees, however, escaped wasp attacks.

Even if fringe trees don’t turn out to suffer massive damage, they could still present a very real threat if nurseries shipping trees from infested areas accidentally transport beetle larvae, too, Hoban says. Besides spreading the pests, that could make it tougher for ashes to weather existing invasions. The hope for ashes is that wasps will help keep beetles in check, and some exceptional ash trees will prove resistant enough to rebuild some sort of population.

Editor’s note: This story was updated November 23 to change the photo at the top of the story. The original photo was not an emerald ash borer.

Liquid methane and ethane flow through a subterranean plumbing system on Titan, which drains lakes and connects seas. That’s one of the first scientific results from the latest, most complete map of the Saturnian moon’s topography.

Planetary scientist Paul Corlies of Cornell University and colleagues released the map — based on all the data from NASA’s Cassini mission, which ended in September (SN Online: 9/15/17) — in Geophysical Research Letters on December 2.

Titan, Saturn’s largest moon, hosts seas, lakes, clouds and rain — all composed of hydrocarbons such as methane and ethane instead of water. The elevations of seas and mountains across 9 percent of Titan’s surface were directly recorded by Cassini as it flew past Titan over 13 years. The researchers had to infer altitudes for the rest of the globe.
Compared with previous maps, the new one adds mountains in the southern hemisphere and shows that Titan is more of a squashed sphere than previously thought. Researchers can now use the map to build computer simulations of everything from Titan’s atmosphere to its interior structure. “Within hours of the paper actually being available online, people we’ve never collaborated with started contacting [Corlies] to ask how to get the data,” says study coauthor Alexander Hayes, a planetary scientist also at Cornell.

But the first study to use the map, also published December 2 in Geophysical Research Letters, is research that Hayes has been working on for a decade. The work shows that Titan has a sea level as well as the hydrocarbon equivalent of groundwater — pores in subsurface rock are filled with liquid that can seep into and between the lakes and seas.

“Looking for actual evidence that the lakes could be communicating was a fundamental question from Cassini,” Hayes says. “This is the final paper that gives the best evidence that it exists.”
His team analyzed the altitudes of Titan’s liquid bodies and found that the three largest seas — Ligeia Mare, Kraken Mare and Punga Mare— are all about the same elevation, just like Earth’s oceans. In other words, Titan has a sea level, Hayes says. To maintain that uniformity, the seas must be connected through channels that could be above or below ground.
The moon’s poles are dotted with small lakes and depressions that are shaped like lakes but contain no liquid. Hayes and colleagues found that the liquid levels of the filled lakes are above sea level, so they are potentially isolated from the seas. If the lakes and seas were connected, the lakes’ liquid could drain into the seas, and the liquids’ surface heights would all match — or the lakes would be empty.

The floors of the dry lake beds are at a higher elevation still. Hayes thinks that may indicate that their liquid flowed into the filled polar lakes. Those hydrological connections probably occur underground because there do not appear to be enough connections on the surface. If scientists could dig deeper into a dry lake, he predicts, they would hit liquid at the level of the filled lakes’ surfaces.

A remaining mystery is how the small polar lakes formed. Both the dry and filled lakes have steep walls, flat floors and rims that rise above the surrounding ground — features that lakes on Earth tend not to have. “They look like you went around Titan’s polar region with a cookie cutter and cut out little shapes,” Hayes says.

His best guess is that the lakes are sinkholes (SN: 1/25/14, p. 14), which collapsed when the bedrock material was dissolved out from under them. If true, then Titan’s poles may be covered with a thick layer of a kind of solid that hydrocarbons can dissolve, like acetylene. But sinkholes shouldn’t have raised rims, so that theory doesn’t explain everything.

The researchers hope other investigators will have some new ideas. “We’re just saying, these are all the observations. Please tell us how they fit together,” Hayes says.

Planetary scientist Jani Radebaugh of Brigham Young University in Provo, Utah, thinks the odd lakes could be the remnants of icy volcanoes. Explosive eruptions could create the raised rims, and the depressions could be empty magma chambers that collapsed. “I think we should consider it,” she says.

But she agrees that Hayes’ groundwater theory makes sense. Seeing hydrological systems on Titan that are similar to Earth’s “is satisfying, and helps to validate that what we understand from the Earth should work on other bodies, regardless of what the liquid is made of,” she says.

There’s so much water on some of TRAPPIST-1’s seven Earth-sized planets that any life lurking there might be difficult to detect.

New estimates of the makeup of these potentially habitable worlds suggests that two of them are more than half water, by mass, researchers report March 19 in Nature Astronomy. Earth, by comparison, is less than 0.1 percent water.

TRAPPIST-1’s planets are so wet that most of the water probably isn’t even liquid, but ice formed under high pressure, says Cayman Unterborn, an exogeologist at Arizona State University in Tempe. That would change the chemistry happening on the planet in a way that could make any signs of life tricky to distinguish from geochemical processes.
TRAPPIST-1 is a cool, dim star about 39 light-years from Earth. Since the star system’s discovery in 2017, it’s been a prime focus for scientists seeking life outside of our solar system because some of the seven planets might have the right conditions to host life (SN: 12/23/17, p. 25). They’re rocky rather than gaseous, and at least three are at a distance from the star that could let them host liquid water.

Unterborn and his colleagues used previous estimates of the mass and diameter of TRAPPIST-1’s planets to calculate the worlds’ densities. Then, the team used a computer program to test different compositions of basic planetary building blocks to determine which makeups would yield planets with those densities.
Frozen or liquid water is less dense than rock, but more dense than a gas. So a less dense planet might have a higher proportion of water or gases compared with a denser, rockier world. But Unterborn doesn’t think the TRAPPIST-1 planets are massive enough to hold onto much of an atmosphere — it would probably escape into space. So the team concluded the lower densities in this system probably come from the presence of water.
The researchers focused on four of the seven planets for which they had the best data. The first and second planets from the dwarf star are probably less than 15 percent water by mass, still far wetter than Earth, the researchers found.

The fifth and sixth planets, both in the habitable zone, are more than half water — a volume so large that the water pressure alone could force much of it into a form of ice, Unterborn says. He estimates that on the fifth planet, TRAPPIST-1f, liquid water extends down about 200 kilometers — about 20 times deeper than the Mariana Trench on Earth. Below that, a nearly 2,300-kilometer layer of ice stretches almost halfway to the center of the planet.

These water estimates might throw a wet blanket on the chances of finding life on any of TRAPPIST-1’s planets, if it exists at all. The thick covering of ice and water might mess up some of the geological processes that, at least on Earth, help regulate the planet’s temperature over long periods of time. If so, that might be an impediment to life getting a foothold. Having so much water might also slow or halt the movement of building blocks of life, such as carbon and phosphorus (the backbone of DNA), into oceans. That could make it harder for us to detect whether certain molecules in the water are hints of the presence of living organisms, or just the by-products of geological processes.

It doesn’t rule out life, Unterborn says, but it does make it harder to find. When it comes to understanding the way a planet’s geologic composition affects chemical processes, “the vast majority of data that’s out there is for one planet, and it’s ours,” he says. The TRAPPIST-1 system is “such an extreme of rocky planet chemistry.”

Updated estimates of the TRAPPIST-1 planets’ masses were published in February (SN Online: 2/5/18), and this study doesn’t use those numbers, says Billy Quarles, a physicist at the University of Oklahoma in Norman who wasn’t part of the study. Based on the newer estimates, TRAPPIST-1’s planets aren’t quite as wet as this study predicts. But the big-picture conclusion — that some of the planets contain far more water than Earth — still holds up, he says.