The photosynthesizing plankton Emiliania huxleyi has a dramatic relationship with its bacterial frenemies. These duplicitous bugs help E. huxleyi in exchange for nutrients until it becomes more convenient to murder and eat their hosts. Now, scientists have figured out how these treacherous bacteria decide to turn from friend to foe.

One species of these bacteria appears to keep tabs on health-related chemicals produced by E. huxleyi, researchers report January 24 in eLife. The bacteria maintain their friendly facade until their hosts age and weaken, striking as soon as the vulnerable algae can’t afford to keep bribing them with nutrients. The finding could help explain how massive algal blooms come to an end.
The bacteria is “first establishing what we call the ‘first handshake,’” says marine microbiologist Assaf Vardi of the Weizmann Institute of Science in Rehovot, Israel. “Then it will shift into a pathogen.”

E. huxleyi’s partnership with these bacteria, which belong to a group called Roseobacter, might be best described as a love-hate relationship. The single-celled alga can’t produce the B vitamins it needs on its own, so it offers up nutrients to lure in Roseobacter that can (SN: 7/8/16). The trade is win-win — at least until the bacteria decide they’d be better off slaying and devouring their algal hosts than sticking around in peaceful coexistence.

Sometimes called the “Jekyll-and-Hyde” trait, this kind of bacterial backstabbery shows up everywhere from animal guts to the open seas. But it wasn’t clear before how Roseobacter decide it’s the right moment to murder E. huxleyi.

Vardi’s team exposed a type of Roseobacter that lives with E. huxleyi to chemicals taken from algae that were either young and growing or old and stagnant. The team also introduced the bacteria to extra doses of a certain health-signaling algal chemical.Looking at which genes the bacteria activated in the different experiments revealed how and why they switched from friend to foe.

The bacteria kill their algal pals when exposed to high concentrations of a sulfur-containing chemical called DMSP, the researchers found. E. huxleyi leaks more and more DMSP as it ages. This eventually cues its duplicitous microbial partners to go rogue, kill their aging host, and kick their genes for nutrient-grabbing proteins and flagella — whiplike tails used to swim — into overdrive.

It’s an “eat-and-run strategy,” says Noa Barak-Gavish, a microbiologist at ETH Zurich. “You eat up whatever you can and then swim away to avoid competition … [and] to find alternative hosts.”

DMSP isn’t the only figure in this deadly chemical calculus. E. huxleyi can sate its companion’s bloodlust with a bribe of benzoate, a nutrient that Roseobacter can use but most bacteria can’t.

While it’s clearer now what drives the bacteria to kill their hosts, their murder weapon remains a mystery. Vardi says his group has some hunches to follow up on.

This kind of frenemies relationship could be a key factor in controlling the boom and bust of massive algal blooms if other phytoplankton and bacteria have a similar dynamic, says Mary Ann Moran of the University of Georgia in Athens, who was not involved in the study. Algal blooms can be toxic (SN: 8/28/18). But they also “fix” enormous amounts of carbon dioxide into biomass and are a major source of organic carbon to the ocean.
“Phytoplankton fix half of all the carbon on the planet, and probably 20 percent to 50 percent of what they fix … actually goes right to bacteria,” she says. So if this kind of relationship controls how carbon flows through the ocean, “that is something that we would really like to understand.”

Vikings brought horses and dogs to the British Isles from Scandinavia, a new study suggests.

A chemical analysis of bone fragments from a cemetery in England provides the first solid scientific evidence of animals traveling with Vikings across the North Sea, scientists report February 1 in PLOS ONE.

In the 1990s, researchers unearthed the cremated remains of a human adult and child as well as of a dog, horse and probable pig from a burial mound in a Viking cemetery in Derbyshire, England. In previous work, radiocarbon dating of femur, skull and rib fragments revealed that the inhabitants all died sometime between the eighth and 10th centuries. That date was narrowed down to the year 873, thanks to the ninth-century Anglo-Saxon Chronicle, which records that a Viking army wintered near the site that year.
Where the animals came from has been a mystery. Norse raiders are known to have stolen horses from people in England around the time. And researchers have generally thought that Viking boats at the time were too small to allow for much transport of animals from Scandinavia to the British Isles. One entry in the Anglo-Saxon Chronicle describes Vikings moving from France to England along with their horses in the year 892, but no physical evidence of such activity had been found before.

In the new work, Tessi Löffelmann and colleagues turned to certain forms, or isotopes, of strontium to unravel the individuals’ provenance. The element accumulates in bones over time through diet, leaving a distinct signature of where an individual has lived (SN: 4/2/19).
Strontium ratios in the child’s remains matched those of shrubs growing at the burial site, suggesting the child spent most, if not all, of its life in England. The ratios of the adult and three animals, on the other hand, differed substantially from the local fauna, the team found. That suggests the individuals hadn’t spent much time in the country before they died. Instead, their ratios were similar to ones found in the Baltic Shield region in Norway, central and northern Sweden and Finland, suggesting a Scandinavian origin.

“One of the joys of isotope analysis is that you are able to really pinpoint things that previously we could discuss endlessly,” says Marianne Moen, an archeologist at the University of Oslo who was not involved in the study. Using strontium to analyze more cremated remains, which can elude common forms of isotope analysis including carbon and nitrogen, “is the next logical chapter for understanding prehistoric mobility.”

Isotope analysis helped reveal where these individuals lived and when they died, but it couldn’t answer why the dog, horse and pig made the journey to England in the first place. That’s where historical records can help, says Löffelmann, of Durham University in England and Vrije Universiteit Brussel in Belgium.

For Löffelmann, the small sizes of early Norse ships combined with the fact that the animals and people were buried together suggest Vikings may have initially brought animals with them for companionship, not just function.

“It could have only been selected animals that made that journey,” she says. “They were important to what the person was.… They went through life together, and now they’re going through death.”

A crucial link in the life cycle of one parasitic plant may be found in a surprising place — the bellies of the descendants of an ancient line of rabbits.

Given their propensity for nibbling on gardens and darting across suburban lawns, it can be easy to forget that rabbits are wild animals. But a living reminder of their wildness can be found on two of Japan’s Ryukyu Islands, if you have the patience to look for it: the endangered Amami rabbit, a “living fossil” that looks strikingly similar to ancient Asian rabbits.
One estimate suggests there are fewer than 5,000 of the animals left in the wild. The lives of Amamis (Pentalagus furnessi) are shrouded in mystery due to their rarity, but they seem to play a surprising ecological role as seed dispersers, researchers report January 23 in Ecology.

Seed dispersal is the main point in a plant’s life cycle when it can move to a new location (SN: 11/14/22). So dispersal is crucially important for understanding how plant populations are maintained and how species will respond to climate change, says Haldre Rogers, a biologist at Virginia Tech in Blacksburg, who was not involved with the study. Despite this, seed dispersal hasn’t received much attention, she says. “We don’t know what disperses the seeds of most plants in the world.”

Locals from the Ryukyu Islands were the first to notice that the “iconic yet endangered” Amami rabbit was nibbling on the fruit of another local species, the plant Balanophora yuwanensis, says Kenji Suetsugu, a biologist at Kobe University in Japan.

Rabbits generally like to eat vegetative tissue from plants, like leaves and stems, and so haven’t been thought to contribute much to spreading seeds, which are often housed in fleshy fruits.

To confirm what the locals reported, Suetsugu and graduate student Hiromu Hashiwaki set up camera traps around the island to catch the rabbits in the act. The researchers were able to record rabbits munching on Balanophora fruits 11 times, but still needed to check whether the seeds survived their trip through the bunny tummies.
So the team headed out to the subtropical islands and scooped up rabbit poop, finding Balanophora seeds inside that could still be grown. By swallowing the seeds and pooping them out elsewhere, the Amami rabbits were clearly acting as seed dispersers.

Balanophora plants are parasitic and don’t have chlorophyll, so they can’t use photosynthesis to make food of their own (SN: 3/2/17). Instead, they suck energy away from a host plant. This means where their seeds end up matters, and the Amami rabbits “may facilitate the placement of seeds near the roots of a compatible host” by pooping in underground burrows, Suetsugu says. “Thus, the rabbits likely provide a crucial link between Balanophora and its hosts” that remains to be further explored, he says.
Understanding the ecology of an endangered species like the Amami rabbit can help with conserving both it and the plants that depend on it.

An animal need not be in obvious peril for a change in its number to affect seed dispersal, with potentially negative consequences for the ecosystem. For example, “we think of robins as super common … but they’ve declined a lot in the last 50 years,” Rogers says. “Half as many robins means half as many seeds are getting moved around, even though no one’s worried about robins as a conservation issue.”

The one-of-a-kind pattern of ridges and valleys in a fingerprint may not only betray who was present at a crime scene. It may also tattle about what outlawed drugs a suspect handled.

With advanced spectroscopy, researchers can detect and measure tiny flecks of cocaine, methamphetamine and heroin — in some cases as little as trillionths of a gram — on a lone fingerprint. The study, led by researchers at the National Institute of Standards and Technology in Gaithersburg, Md., appears May 7 in Analytical Chemistry.
Using an ink-jet–printed array of known quantities of drugs, researchers calibrated their spectroscopy techniques to measure specks of the chemicals. Then, using a 3-D printed plastic finger and a synthetic version of finger oil, researchers created drug-tainted fingerprints pressed onto paper or silicon.

On paper, the researchers detected as little as 1 nanogram of cocaine and amounts above 50 nanograms of methamphetamine and heroin. On silicon, the method picked up as little as 8 picograms of cocaine and heroin and around 1 nanogram of methamphetamine.

Researchers could also point to the location of the drugs on the fingerprint— at the peaks or dips of the pattern, for instance. Such information, the authors say, could help investigators finger what chemicals a suspect handled first and help corroborate a timeline of events in a crime.

In the animal world, just like the human one, sometimes it’s not easy being mom. Fellow blogger Laura Sanders will tell you all about the trials and tribulations of being a mother to Homo sapiens. But some moms of the animal kingdom make sacrifices that go far beyond carrying a baby for nine months or paying for college.

Binge-eating sea otters
Adult female sea otters spend six months out of every year nursing at least one pup, sometimes two. Feeding herself isn’t easy — she’s got to eat the equivalent of 20 to 25 percent of her body mass every day to survive. But that amount has to increase while she’s nursing. By the time a pup is weaned at six months old, mom has to nearly double her food intake, researchers reported last year in the Journal of Experimental Biology. And to make matters worse, sometimes her kid will steal her food.
Single, starving mom
About two months before giving birth, a polar bear will enter her maternity den, remaining there for four to eight months. She stays holed up for that entire time, never eating, never drinking. Her cubs, only about half a kilogram at birth, grow quickly feeding on mom’s rich milk. And once they’re big enough to venture out, mama bear leads her babies straight to the sea so she can finally catch herself a meal.

Walled in by poo
Various species of Asian hornbills all share a similar nesting strategy: To protect her eggs from predators, mom walls herself up in a tree with a combination of mud, feces and regurgitated fruit. She leaves one tiny hole, through which dad feeds her for up to four months when mother and children are finally ready to emerge.

Endless sleepless nights
Human babies are known for their ability to rouse mom with their cries and prevent her from getting much sleep. But orca and dolphin moms don’t sleep at all for a month or more after they give birth. Unlike human babies that need a lot of sleep, tiny orcas and dolphins don’t sleep in the weeks after they’re born. That means no sleep for mom.

It’s mom for dinner
There’s a hint in the name of a limbless amphibian called Microcaecilia dermatophaga — young caecilians eat the skin of their mother, researchers reported in 2013 in PLOS ONE. But in a recent issue of Science News, Susan Milius highlighted an even more disgusting case of mom serving herself up for her kids: A female Stegodyphus lineatus spider feeds her young on a regurgitated slurry made up of the last meals she’ll ever eat — and her own guts. Milius writes:

“As liquid wells out on mom’s face, spiderlings jostle for position, swarming over her head like a face mask of caramel-colored beads. This will be her sole brood of hatchlings, and she regurgitates 41 percent of her body mass to feed her spiderlings.”

The next time your mom talks about how much she sacrificed for you, say thanks, but remember, at least you didn’t eat her stomach.

Mother’s Day is on my mind, and I’ve been thinking about the ways I’m connected to my mom and my two little daughters. Every so often I see flickers of my mom in my girls — they share the lines around their smiles and a mutual adoration of wildflowers. Of course, I’m biased. I know that I’m seeing what I’m looking for. But biologically speaking, mothers and their children are connected in a way that may surprise you.

Way back when you and your mom shared a body, your cells mingled. Her cells slipped into your body and your cells circled back into her. This process, called fetal-maternal microchimerism, turns both mother and child into chimeras harboring little pieces of each other.

Cells from my daughters are knitted into my body and bones and brain. I also carry cells from my mom, and quite possibly from my grandma. I may even harbor cells from my older brother, who may have given some cells to my mom, who then gave them to me. It means my younger brother just might have cells from all of us, poor guy. This boundary blurring invites some serious existential wonder, not least of which might involve you wondering if this means your family members really are in your head.

These cellular threads tie families together in ways that scientists are just starting to discover. Here are a few of my favorite instances of how cells from a child have woven themselves into a mother’s body:
Fetal cells are probably sprinkled throughout a mother’s brain. A study of women who had died in their 70s found that over half of the women had male DNA (a snippet from the Y chromosome) in their brains, presumably from when their sons were in the womb. Scientists often look for male DNA in women because it’s easier than distinguishing a daughter’s DNA from her mother’s. If DNA from daughters were included, the number of women with children’s cells in their brains would probably be even higher.

When the heart is injured, fetal cells seem to flock to the site of injury and turn into several different types of specialized heart cells. Some of these cells may even start beating, a mouse study found. So technically, those icky-sweet Mother’s Day cards may be right: A mother really does hold her children in her heart.

Fetal cells circulate in a mother’s blood. Male DNA turned up in blood samples from women who were potential stem cell donors. That result may have implications for stem cell transplants. This cell swapping may make parents better donor candidates for their children than strangers, for instance.
Other studies have found fetal cells in a mother’s bones, liver, lungs and other organs, suggesting that these cells have made homes for themselves throughout a mother’s body. Maybe this is a way for a child to give back to the mother, in a sense. Growing fetuses slurp nutrients and energy out of a mother’s body during pregnancy (not to mention the morning sickness, heartburn and body aches). In return, fetuses offer up these young, potentially helpful cells. Perhaps these fetal cells, which may possess the ability to turn into lots of different kinds of cells, can help repair a damaged heart, liver or thyroid, as some studies have hinted.

Before I get carried away, a caveat: these cells may also make mischief. They may have a role in autoimmune disorders, for instance.

Microchimerism also has implications here for women who have lost pregnancies, an extremely common situation hidden by the taboo of talking about miscarriages. Fetal cells seem to migrate early in pregnancy, meaning that even brief pregnancies may leave a cellular mark on a woman.

Scientists are just starting to discover how this cellular heritage works, and how it might influence health. The scientist in me can’t wait to see how this story unfolds. But for now, I’m content to marvel at the mother and daughters in me.

A new high-tech glove totally sucks — and that’s a good thing.

Each fingertip is outfitted with a sucker inspired by those on octopus arms. These suckers allow people to grab slippery, underwater objects without squeezing too tightly, researchers report July 13 in Science Advances.

“Being able to grasp things underwater could be good for search and rescue, it could be good for archaeology, [and] could be good for marine biology,” says mechanical engineer Michael Bartlett of Virginia Tech in Blacksburg.
Each sucker on the glove is a raspberry-sized rubber cone capped with a thin, stretchy rubber sheet. Vacuuming the air out of a sucker pulls its cap into a concave shape that sticks to surfaces like a suction cup. Pumping air back into the sucker inflates its cap, causing it to pop off surfaces. Each finger is also equipped with a Tic Tac–sized sensor that detects nearby surfaces. When the sensor comes within some preset distance of any object, it switches the sucker on that finger to sticky mode.

Bartlett and colleagues used the glove to pick up objects underwater, including a toy car, plastic spoon and metal bowl. Each sucker could lift about one kilogram in open air — and could lift more underwater, with the help of buoyancy, Bartlett says. Adding more suckers could give the glove an even stronger grip.
The octopus-inspired glove barely brushes the surface of what octopuses and other cephalopods can do. Octopuses can individually control thousands of suckers across their eight arms to feel around the seafloor and snatch prey. The suckers do this using not only tactile sensors, but also chemical-detecting cells that “taste” their surroundings (SN: 10/29/20).

The new glove is far from turning fingers into extra tongues. But Bartlett is intrigued by the possibility of adding chemical sensors so that the suckers stick to only certain materials.

Humans have long tried to wrangle water. We’ve straightened once-meandering rivers for shipping purposes. We’ve constructed levees along rivers and lakes to protect people from flooding. We’ve erected entire cities on drained and filled-in wetlands. We’ve built dams on rivers to hoard water for later use.

“Water seems malleable, cooperative, willing to flow where we direct it,” environmental journalist Erica Gies writes in Water Always Wins. But it’s not, she argues.

Levees, which narrow channels causing water to flow higher and faster, nearly always break. Cities on former wetlands flood regularly — often catastrophically. Dams starve downstream environs of sediment needed to protect coastal areas against rising seas. Straightened streams flow faster than meandering ones, scouring away riverbed ecosystems and giving water less time to seep downward and replenish groundwater supplies.

In addition to laying out this damage done by supposed water control, Gies takes readers on a hopeful global tour of solutions to these woes. Along the way, she introduces “water detectives”— scientists, engineers, urban planners and many others who, instead of trying to control water, ask: What does water want?
These water detectives have found ways to give the slippery substance the time and space it needs to trickle underground. Around Seattle’s Thornton Creek, for instance, reclaimed land now allows for regular flooding, which has rejuvenated depleted riverbed habitat and created an urban oasis. In California’s Central Valley, scientists want to find ways to shunt unpolluted stormwater into ancient, sediment-filled subsurface canyons that make ideal aquifers. Feeding groundwater supplies will in turn nourish rivers from below, helping to maintain water levels and ecosystems.

While some people are exploring new ways to manage water, others are leaning on ancestral knowledge. Without the use of hydrologic mapping tools, Indigenous peoples of the Andes have a detailed understanding of the plumbing that links surface waters with underground storage. Researchers in Peru are now studying Indigenous methods of water storage, which don’t require dams, in hopes of ensuring a steady flow of water to Lima — Peru’s populous capital that’s periodically afflicted by water scarcity. These studies may help convince those steeped in concrete-centric solutions to try something new. “Decision makers come from a culture of concrete,” Gies writes, in which dams, pipes and desalination plants are standard.

Understanding how to work with, not against, water will help humankind weather this age of drought and deluge that’s being exacerbated by climate change. Controlling water, Gies convincingly argues, is an illusion. Instead, we must learn to live within our water means because water will undoubtedly win.

Pocket gophers certainly don’t qualify as card-carrying 4-H members, but the rodents might be farming roots in the open air of their moist, nutrient-rich tunnels.

The gophers subsist mostly on roots encountered in the tunnels that the rodents excavate. But the local terrain doesn’t always provide enough roots to sustain gophers, two researchers report in the July 11 Current Biology. To make up the deficit, the gophers practice a simple type of agriculture by creating conditions that promote more root growth, suggest ecologist Jack Putz of the University of Florida in Gainesville and his former zoology undergraduate student Veronica Selden.
But some scientists think it’s a stretch to call the rodents’ activity farming. Gophers aren’t actively working the soil, these researchers say, but inadvertently altering the environment as the rodents eat and poop their way around — much like all animals do.

Tunnel digging takes a lot of energy — up to 3,400 times as much as walking along the surface for gophers. To see how the critters were getting all this energy, Selden and Putz in 2021 began investigating the tunnels of southeastern pocket gophers (Geomys pinetis) in an area being restored to longleaf pine savanna in Florida that Putz partially owns.

The pair took root samples from soil adjacent to 12 gopher tunnels and extrapolated how much root mass a gopher would encounter as it excavated a meter of tunnel. Then the researchers calculated the amount of energy that those roots would provide.

“We were able to compare energy cost versus gain, and found that on average there is a deficit, with about half the cost of digging being unaccounted for,” Selden says.

Upon examining some tunnels, Selden and Putz saw gopher feces spread through the interior along with signs of little bites taken out of roots and churning of the soil.

The gophers, the researchers conclude, provide conditions that favor root growth by spreading their own waste as fertilizer, aerating the soil and repeatedly nibbling on roots to encourage new sprouting.

“All of these activities encourage root growth, and once the roots grow into the tunnels, the gophers crop the roots,” Selden says. She and Putz say that this amounts to a rudimentary form of farming. If so, gophers would be the first nonhuman mammals to be recognized as farmers, Putz says. Other organisms, such as some insects, also farm food and started doing so much earlier than humans (SN: 4/23/20).

But the study has its skeptics. “I don’t really think you can call it farming per the human definition. All herbivores eat plants, and everybody poops,” says J.T. Pynne, a wildlife biologist at the Georgia Wildlife Federation in Covington who studies southeastern pocket gophers. So the root nibbling and tunnel feces might not be signs of agriculture, just gophers doing what all animals do.

Evolutionary biologist Ulrich Mueller agrees. “If we accept the tenuous evidence presented in the Selden article as evidence for farming … then most mammals and most birds are farmers because each of them accidentally have also some beneficial effects on some plants that these mammals or birds also feed on,” he says.

Not only that, but the study is also dangerous, says Mueller, of the University of Texas at Austin. The public will see through “the shallowness of the data,” he says, and will conclude that science is “just a bunch of storytelling, eroding general trust in science.”

For her part, Selden says she understands that because gophers don’t plant their crops, not everyone is comfortable calling them farmers. Still, she argues that “what qualifies the gophers as farmers and sets them apart from, say, cattle, which incidentally fertilize the grass they eat with their wastes, is that gophers cultivate and maintain this ideal environment for roots to grow into.”

At the very least, Putz says, he hopes their research makes people kinder toward the rodents. “If you go to the web and put in ‘pocket gopher,’ you’ll see more ways to kill them than you can count.”

In the beginning, scientists believe there was an interstellar gas cloud of all the elements comprising the Earth. A billion or so years later, the Earth was a globe of concentric spheres with a solid iron inner core, a liquid iron outer core and a liquid silicate mantle…. The current theory is that the primeval cloud’s materials accreted … and that sometime after accretion, the iron, melted by radioactive heating, sank toward the center of the globe…. Now another concept is gaining ground: that the Earth may have accreted … with core formation and accretion occurring simultaneously.

Update
Most scientists now agree that the core formed as materials that make up Earth collided and glommed together and that the process was driven by heat from the smashups. The planet’s heart is primarily made of iron, nickel and some oxygen, but what other elements may dwell there and in what forms remains an open question. Recently, scientists proposed the inner core could be superionic, with liquid hydrogen flowing through an iron and silicon lattice (SN: 3/12/22, p. 12).