Herminia Pasantes discovered how taurine helps brain cells regulate their size

When Herminia Pasantes Ordóñez was about 14 years old, in 1950, she heard her mother tell her father that she would never find a husband. Pasantes had to wear thick glasses for her poor eyesight. In her mother’s eyes, those glasses meant her future as a “good woman” was doomed. “This made my life easier,” says Pasantes, “because it was already said that I was going to study.”

At a time when it was uncommon for women to become scientists, Pasantes studied biology at the National Autonomous University of Mexico in Mexico City, or UNAM. She was the first member of her family to go to college.
She became a neurobiologist and one of the most important Mexican scientists of her time. Her studies on the role of the chemical taurine in the brain offer deep insights into how cells maintain their size — essential to proper functioning. In 2001, she became the first woman to earn Mexico’s National Prize for Sciences and Arts in the area of physical, mathematical and natural sciences.

“We basically learned about cell volume regulation through the eyes and work of Herminia,” says Alexander Mongin, a Belarusian neuroscientist at Albany Medical College in New York.

Pasantes did get married, in 1965 while doing her master’s in biochemistry at UNAM. She had a daughter in 1966 and a son in 1967 before starting a Ph.D. in natural sciences in 1970 at the Center for Neurochemistry at the University of Strasbourg in France. There, she worked in the laboratory of Paul Mandel, a Polish pioneer in neurochemistry.

The lab was trying to find out everything there was to know about the retina, the layer of tissue at the back of the eye that is sensitive to light. Pasantes decided to test whether free amino acids, a group that aren’t incorporated into proteins, were present in the retinas and brain of mice. Her first chromatography — a lab technique that lets scientists separate and identify the components of a sample — showed an immense amount of taurine in both tissues. Taurine would drive the rest of her scientific career, including work in her own lab, which she started around 1975 at the Institute of Cellular Physiology at UNAM.

Taurine turns out to be widely distributed in animal tissues and has diverse biological functions, some of which were discovered by Pasantes. Her research found that taurine helps maintain cell volume in nerve cells, and that it protects brain, muscle, heart and retinal cells by preventing the death of stem cells, which give rise to all specialized cells in the body.
Contrary to what most scientists had believed at the time, taurine didn’t work as a neurotransmitter sending messages between nerve cells. Pasantes demonstrated for the first time that it worked as an osmolyte in the brain. Osmolytes help maintain the size and integrity of cells by opening up channels in their membranes to get water in or out.

Pasantes says she spent many years looking for an answer for why there is so much taurine in the brain. “When you ask nature a question, 80 to 90 percent of the time, it responds no,” she says. “But when it answers yes, it’s wonderful.”

Pasantes’ lab was one of the big four labs that did groundbreaking work on cell volume regulation in the brain, says Mongin.

Her work and that of others proved taurine has a protective effect; it’s the reason the chemical is today sprinkled in the containers that carry organs for transplants. Pasantes’ work was the foundation for our understanding of how to prevent and treat brain edema, a condition where the brain swells due to excessive accumulation of fluid, from head trauma or reduced blood supply, for example. She and other experts also reviewed the role of taurine for Red Bull, which added the chemical to its formula because of potentially protective effects in the heart.

Pasantes stopped doing research in 2019 and spends her time talking and writing about science. She hopes her story speaks to women around the world who wish to be scientists: “It is important to send the message that it is possible,” she says.

Years before she was accepted into Mandel’s lab, her application to a Ph.D. in biochemistry at the UNAM was rejected. Pasantes says the reason was that she had just had her daughter. Looking back, this moment was “one of the most wonderful things that could’ve happened to me,” Pasantes says, because she ended up in Strasbourg, where her potential as a researcher bloomed.

Rosa María González Victoria, a social scientist at the Autonomous University of the State of Hidalgo in Pachuca, Mexico, who specializes in gender studies, recently interviewed Pasantes for a book about Mexican women in science. González Victoria thinks Pasantes’ response to that early rejection speaks to the kind of person she is: “A woman that takes those no’s and turns them into yes’s.”

The heaviest neutron star on record is 2.35 times the mass of the sun

A fast-spinning neutron star south of the constellation Leo is the most massive of its kind seen so far, according to new observations.

The record-setting collapsed star, named PSR J0952-0607, weighs about 2.35 times as much as the sun, researchers report July 11 on arXiv.org. “That’s the heaviest well-measured neutron star that has been found to date,” says study coauthor Roger Romani, an astrophysicist at Stanford University.

The previous record holder was a neutron star in the northern constellation Camelopardalis named PSR J0740+6620, which tipped the scales at about 2.08 times as massive as the sun. If a neutron star grows too massive, it collapses under its own weight and becomes a black hole. These measurements of hefty neutron stars are of interest because no one knows the exact mass boundary between neutron stars and black holes.
That dividing line drives the quest to find the most massive neutron stars and determine just how massive they can be, Romani says. “It’s defining the boundary between the visible things in the universe and the stuff that is forever hidden from us inside of a black hole,” he says. “A neutron star that’s on the hairy edge of becoming a black hole — just about heavy enough to collapse — has at its center the very densest material that we can access in the entire visible universe.”

PSR J0952-0607 is in the constellation Sextans, just south of Leo. It resides 20,000 light-years from Earth, far above the galaxy’s plane in the Milky Way’s halo. The neutron star emits a pulse of radio waves toward us each time it spins, so astronomers also classify the object as a pulsar. First reported in 2017, this pulsar spins every 1.41 milliseconds, faster than all but one other pulsar.

That’s why Romani and his colleagues chose to study it — the fast spin led them to suspect that the pulsar might be unusually heavy. That’s because another star orbits the pulsar, and just as water spilling over a water wheel spins it up, gas falling from that companion onto the pulsar could have sped up its rotation while also boosting its mass.

Observing the companion, Romani and his colleagues found that it whips around the pulsar quickly — at about 380 kilometers per second. Using the companion’s speed and its orbital period of about six and a half hours, the team calculated the pulsar’s mass to be more than twice the mass of the sun. That’s a lot heavier than the typical neutron star, which is only about 1.4 times as massive as the sun.

“It’s a terrific study,” says Emmanuel Fonseca, a radio astronomer at West Virginia University in Morgantown who measured the mass of the previous record holder but was not involved in the new work. “It helps nuclear physicists actually constrain the nature of matter within these extreme environments.”

Mammal ancestors’ shrinking inner ears may reveal when warm-bloodedness arose

Hot or not? Peeking inside an animal’s ear — even a fossilized one — may tell you whether it was warm- or cold-blooded. Using a novel method that analyzes the size and shape of the inner ear canals, researchers suggest that mammal ancestors abruptly became warm-blooded about 233 million years ago, the team reports in Nature July 20.

Warm-bloodedness, or endothermy, isn’t unique to mammals — birds, the only living dinosaurs, are warm-blooded, too. But endothermy is one of mammals’ key features, allowing the animals to regulate their internal body temperatures by controlling their metabolic rates. This feature allowed mammals to occupy environmental niches from pole to equator, and to weather the instability of ancient climates (SN: 6/7/22).
When endothermy evolved, however, has been a mystery. Based on fossil analyses of growth rates and oxygen isotopes in bones, researchers have proposed dates for its emergence as far back as 300 million years ago.

The inner ear structures of mammals and their ancestors hold the key to solving that mystery, says Ricardo Araújo, a vertebrate paleontologist at the University of Lisbon. In all vertebrates, the labyrinth of semicircular canals in the inner ear contains a fluid that responds to head movements, brushing against tiny hair cells in the ear and helping to maintain a sense of balance. That fluid can become thicker or thinner depending on body temperature.

“Mammals have very unique inner ears,” Araújo says. Compared with cold-blooded vertebrates of similar size, the dimensions of mammals’ semicircular canals — such as thickness, length and radius of curvature — is particularly small, he says. “The ducts are very thin and tend to be very circular compared with other animals.” By contrast, fish have the largest for their body size.

What if, Araújo and his colleagues hypothesized, the size and shape of the ear canals are related to the animal’s body temperature? In warm-blooded animals, the fluid becomes less viscous, and the canals may have shrunk to compensate. If so, it might be possible to trace how the shape of fossilized inner ear canals changed over time to discover when warm-bloodedness emerged in the mammal lineage.

To test that hypothesis, the researchers created a tool they call the “thermo-motility index” to link warm-bloodedness to those inner ear dimensions in 341 different vertebrates. Accounting for size differences, the value of this index turned out to closely track an animal’s body temperature, from fish to reptiles to mammals. Reptiles had low index values; mammals were high.

The team then applied this index to the fossilized ear canals of 56 extinct mammal ancestor species. To their surprise, the data showed a sharp change in inner ear morphology around 233 million years ago. That would correspond to an increase in body temperature of between 5 and 9 degrees Celsius — suggesting that endothermy evolved abruptly around that time, the team concludes.
“The fact that it is a sharp break in the data [suggests] the transition happened rapidly, within about a million years,” says coauthor Kenneth Angielczyk, a paleontologist at the Field Museum in Chicago.

It’s a clever study, says Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the work. “I’ve been using [computed tomography] data to study the shapes of inner ears for years, to try to infer how extinct species moved and how they could hear, and it never occurred to me that inner ear shape is related to metabolism and could be used to predict body temperatures of fossil species.”

However, Brusatte notes that there is a limit to what scientists can glean from fossilized ear canals alone, as they don’t reveal what soft tissues may have been present, such as the hair cells, or the actual viscosity of the ear fluid. “Shape alone may not always be sufficient to predict something as complex as body temperature or metabolic style.”

The timing of the purported shift, about 233 million years ago, corresponds to a geologically brief interlude of highly unstable climate known as the Carnian Pluvial Episode (SN: 9/30/21). “It was a time when global temperatures were changing a lot, and it was also a very wet, humid time,” Angielczyk says. “One of the benefits of endothermy is that it stabilizes the internal body environment, lets you operate independent of environmental conditions.”

The finding highlights how “the whole Triassic was a bit insane,” Araújo says. The start of the Triassic was epically hot, coming on the heels of the “Great Dying” mass extinction at the end of the Permian Period (SN: 12/6/18). Vertebrate species had just begun to recover from that event when they were hit with the Carnian Pluvial Episode. Yet the Triassic also saw the dawn of both mammals and dinosaurs — both of which managed to survive.

It was “a crucial time period in the history of life,” Araújo says. All of that instability may have armed both groups with the evolutionary tools they needed to weather yet another mass extinction at the end of the Triassic 201 million years ago (SN: 7/1/22).

A new technology uses human teardrops to spot disease

Human tears could carry a flood of useful information.

With just a few drops, a new technique can spot eye disease and even glimpse signs of diabetes, scientists report July 20 in ACS Nano.

“We wanted to demonstrate the potential of using tears to detect disease,” says Fei Liu, a biomedical engineer at Wenzhou Medical University in China. It’s possible the droplets could open a window for scientists to peer into the entire body, he says, and one day even let people quickly test their tears at home.
Like saliva and urine, tears contain tiny sacs stuffed with cellular messages (SN: 9/3/13). If scientists could intercept these microscopic mailbags, they could offer new intel on what’s happening inside the body. But collecting enough of these sacs, called exosomes, is tricky. Unlike fluid from other body parts, just a trickle of liquid leaks from the eyes.

So Liu’s team devised a new way to capture the sacs from tiny volumes of tears. First, the researchers collected tears from study participants. Then, the team added a solution containing the tears to a device with two nanoporous membranes, vibrated the membranes and sucked the solution through. Within minutes, the technique lets small molecules escape, leaving the sacs behind for analysis.

The results gave scientists an eyeful. Different types of dry-eye disease shed their own molecular fingerprints in people’s tears, the team found. What’s more, tears could potentially help doctors monitor how a patient’s diabetes is progressing.

Now, the scientists want to tap tears for evidence of other diseases as well as depression or emotional stress, says study coauthor Luke Lee, a bioengineer at Harvard Medical School. “This is just the beginning,” he says. “Tears express something that we haven’t really explored.”

Dogs are great sniffers. A newfound nose-to-brain connection helps explain why

A dog’s brain is wired for smell. Now, a new map shows just how extensive that wiring is.

Powerful nerve connections link the dog nose to wide swaths of the brain, researchers report July 11 in the Journal of Neuroscience. One of these canine connections, a hefty link between areas that handle smell and vision, hasn’t been seen before in any species, including humans.

The results offer a first-of-its-kind anatomical description of how dogs “see” the world with their noses. The new brain map is “awesome, foundational work,” says Eileen Jenkins, a retired army veterinarian and expert on working dogs. “To say that they have all these same connections that we have in humans, and then some more, it’s going to revolutionize how we understand cognition in dogs.”
In some ways, the results aren’t surprising, says Pip Johnson, a veterinary radiologist and neuroimaging expert at Cornell University College of Veterinary Medicine. Dogs are superb sniffers. Their noses hold between 200 million and 1 billion odor molecule sensors, compared with the 5 million receptors estimated to dwell in a human nose. And dogs’ olfactory bulbs can be up to 30 times larger than people’s. But Johnson wanted to know how smell information wafts to brain regions beyond the obvious sniffing equipment.

To build the map, Johnson and colleagues performed MRI scans on 20 mixed-breed dogs and three beagles. The subjects all had long noses and medium heads, and were all probably decent sniffers. Researchers then identified tracts of white matter fibers that carry signals between brain regions. A method called diffusion tensor imaging, which relies on the movement of water molecules along tissue, revealed the underlying tracts, which Johnson likens to the brain’s “road network.”

After odor information enters the nose, it whizzes to the olfactory bulb, a brain structure that sits behind the dogs’ eyes. But from there, it wasn’t clear where the signals went next. When Johnson looked for the tracts in the dog MRI data, she was blown away. “I just kept finding these huge pathways,” she says. “They seem like information freeways running from the nose back into the brain.”
This new dog brain map contains some familiar roads, including those that connect the olfactory bulb to brain areas associated with memories and emotions. In people, those roads explain why a whiff of perfume can transport a person back in time.

But one tract was totally new. This road, thick and obvious, connected the olfactory bulb to the occipital lobe, the part of the dog brain that handles vision. “There have been lots of people who theorized that this connection existed, based on the behavior of trained dogs and detection dogs,” says Jenkins, who currently practices at Huntsville Veterinary Specialists & Emergency in Alabama and who was not involved in this study. “But nobody has been able to prove it. This is fabulous.”

Dogs use all their senses to evaluate their environment. But this newfound connection between smell and sight suggests that the two are intricately linked. Perhaps this anatomical link could be why smell can often compensate when a dog’s sight goes, Johnson says. “Blind dogs can still play fetch.”

Breeding can affect the shapes of dog brains, neuroscientist Erin Hecht of Harvard University and colleagues have found (SN: 9/2/19). It would be interesting to see how these olfactory tracts look in different dog breeds, including scent hounds bred and trained for jobs such as hunting, finding disaster survivors or identifying diseases like cancer or COVID-19, Hecht says (SN: 6/1/22). “This study lays a foundation for future work,” she says.

Johnson and her colleagues aim to explore olfactory tracts of other animals. “I have actually had a play with some cat data,” she says. “Cats have the most amazing olfactory system too, and probably more connections than the dog that I can see.” But dog people, settle down. “That’s only preliminary data,” she quickly adds.

Oldest known avian relative of today’s birds found in China

Two partial skeletons unearthed in northeastern China have dashed the record for the oldest avian relatives of today’s birds.

The remains belonged to a species, Archaeornithura meemannae, that lived 130.7 million years ago — about 6 million years earlier than the previous record holders. Fossil hunters discovered bones of the hummingbird-sized creatures embedded in siltstone slabs in what may have once been a lake. Stubby feathers stipple the ancient birds’ bodies, except for some spots on the legs. These bald patches hint that the animals once waded through watery homes, suggest Chinese Academy of Sciences paleontologist Min Wang and colleagues May 5 in Nature Communications.

Designer drugs hit dangerous lows to bring new highs

The 18-year-old had stabbed himself four times in the neck and chest with a pair of scissors. Alone in his dorm room, he had suddenly felt trapped, convinced that the only way to get out was to kill himself.

When he woke up hours later in a pool of blood, the psychedelic trip that had gripped him was waning. Horrified, he managed to call an ambulance. As he recovered, the college student told Joji Suzuki, an addiction psychiatrist at Brigham and Women’s Hospital in Boston, that he had taken LSD.
Suzuki was suspicious. Months earlier, in the summer of 2013, another student had come in with stab wounds in his back. He claimed to have taken magic mushrooms and said that he had stabbed himself. But psychedelic mushrooms don’t make people violent, and stabbing oneself in the back is not easy to do. Suzuki suspects that the young man with the back wound may have been covering for a friend who was also high. A month later the student was back. He spent five days delirious in the hospital’s intensive care unit, claiming he had taken LSD.

Violence and delirium are not usual effects of LSD. “Even in an overdose, LSD won’t lead to a five-day agitated delirium in the ICU,” Suzuki says. “I knew then that this had to be something else.”

By the time the scissors-wielding student arrived, Suzuki was better prepared. He had found a lab that could test for a little-known hallucinogen called 25I-NBOMe. Sure enough, the student’s blood tested positive. Maybe he thought he was taking LSD, but he had actually ingested a new, more dangerous hallucinogen from a family of drugs called smiles or NBOMes (pronounced en-bombs). People who take NBOMes are prone to stab themselves, says Suzuki, who reported the case in November in the Journal of Psychoactive Drugs. “We see it so many times. It’s bizarre.”

NBOMe overdoses have been appearing in U.S. emergency rooms since around 2012, but little is known about the drugs. They are one of many designer drugs, produced as alternatives for classic but illegal substances such as cocaine, LSD and marijuana. Some of the most popular designer drugs are hallucinogens such as NBOMes, stimulants such as bath salts (named for their resemblance to Epsom salts) and spice — synthetic cannabinoids that mimic marijuana. Each one comes in versions that are more dangerous than the drugs they were made to replace.

When a designer drug first appears for sale — often in gas stations, convenience stores or online — it is technically legal, because its chemical structure is slightly different from the illicit drug it mimics. When the U.S. Drug Enforcement Administration gets wind of the new drug, the agency moves to label the drug “Schedule 1,” meaning that it is not safe and has no known medical use. Dodgy chemists will then tweak the structure a bit and release another wave of slightly different, legal-until-they-get-noticed drugs.

Story continues after table
A lot of the drugs seen on the street today haven’t even been tested in animals, much less in humans, says Jenny Wiley, a behavioral pharmacologist at RTI International in Research Triangle Park, N.C. “People are basically the guinea pigs.”

Though designer drugs have been around for decades, there’s been a recent surge in new compounds, says Jill Head, a forensic chemist at a DEA research lab in Dulles, Va. “In the last five or six years we’ve seen upwards of 350, almost 400 new drugs emerge.”

And each one is somewhat different. “Every drug has its own little story,” says Michael Baumann, who heads the Designer Drug Research Unit, a small team within the National Institute on Drug Abuse in Baltimore. When a new drug appears, it’s up to chemists, pharmacologists and researchers like Baumann to quickly develop tests that will detect the drug in a person’s system and figure out how it works. They want to know the risks it poses and how best to treat people who have bad reactions.

Spicing up drug testing
Though recreational marijuana is legal in four states and the District of Columbia, synthetic cannabinoids are still in demand. Pot remains illegal for people under age 21. Plus, military personnel, police officers, parolees and athletes are all routinely screened for marijuana and other drugs. A big benefit of the newcomer drugs: Commonly used tests don’t look for them.

To improve such testing, Marilyn Huestis, a forensic toxicologist at NIDA, wants to identify the breakdown products of spice and other designer drugs. “The problem is that we’re always behind the manufacturers,” she says. “As quickly as a drug becomes [illegal], immediately other drugs are available on the market.”

To evaluate any new compound, she incubates a sample of the drug with pieces of human liver cells to see how long it takes the cells to break down the compound. The test “tells you something about the potential danger of that drug,” she says. A drug that is slowly metabolized “is going to be active in the body for a longer period of time.”

Huestis then investigates how the drug’s structure changes when the body metabolizes it. For a given drug, she generally finds 12 to 25 different metabolites and identifies the most common ones, so testers can focus on the easiest-to-find compounds in blood or urine samples.

Story continues after sidebar
Like many designer drugs, spice has its origins in the scientific literature, Huestis says. Researchers created synthetic cannabinoids in the 1980s as tools to understand the body’s endocannabinoid system, which is involved in learning, memory, appetite, fighting disease and pain. Chemists were trying to make a compound that could snugly fit into endocannabinoid receptors, proteins that sit on the outside of cells and act as the system’s gateway. They hoped that finding a key to unlock these receptors might lead to more effective painkillers.

“The folks that were making these never in their wildest dreams thought that [the compounds] would be diverted as drugs of abuse,” Baumann says.

But inevitably, clandestine chemists discovered how well synthetic cannabinoids replicate the effects of weed, and started pumping them out. The first five synthetic cannabinoids were declared illegal in 2011.

“People tend to think, well gee, cannabis really isn’t bad for you, how can these be bad for you? But the potency makes a tremendous difference,” Huestis says. Some forms of spice are up to 100 times as potent as weed — a small amount can have a big effect, she adds.

Though many people use the drugs without incident, some forms of spice can cause strokes, heart attacks and kidney damage, she says. Psychosis is also a big problem.

The rat brain on bath salts
Most of Baumann’s research has focused on bath salts, drugs designed to mimic a stimulant called cathinone. Cathinone occurs naturally in the khat plant, which grows on the Arabian Peninsula and in East Africa. Chewing the leaves gives a stimulating boost like that from drinking a cup of coffee, Baumann says. Synthesized by chemists, bath salts are more intense.

Typically sold as a powder, bath salts produce feelings of euphoria and alertness similar to the effects of amphetamines and cocaine, but some chemical forms are even more powerful. MDPV, the most infamous component of the original wave of bath salts, can bring on a powerful crash involving suicidal feelings, delirium and violence. This crash may happen because bath salts thwart communication between parts of the brain — and connectivity gets weaker with higher doses, according to research in rats by Marcelo Febo, a neuroscientist at the University of Florida in Gainesville. He presented the study last year at the Society for Neuroscience annual meeting (SN: 12/13/14, p. 12).

Snorting one line of bath salts can be like doing 10 lines of cocaine, Baumann says. It’s much more potent than what people are used to. High doses or repeated use of bath salts can cause excited delirium with raised body temperature, muscle breakdown and kidney failure. “People die from bath salts,” Baumann says. The biomedical literature is peppered with many more cases of deaths from bath salts than from synthetic cannabinoids.

Bath salts boost dopamine, a reward and pleasure messenger molecule, in the territory between nerve cells in the brain. This is what makes the drug so irresistible to users over time. “We know that anything that pops up dopamine to a significant degree … is going to be addictive,” says Baumann.
Bath salts swell dopamine levels by disrupting the transporter molecules that normally carry dopamine out of the space between nerve cells. Like cocaine, MDPV clogs the ports in the carrier molecule so dopamine can’t be mopped up once it has done its job, Baumann and colleagues reported in 2013 in Neuropsychopharmacology. Instead, the dopamine stays in the space between nerve cells and keeps on signaling, activating a wide array of messages within the brain.
“In this case, [MDPV] is outcompeting the dopamine,” Baumann says. The dopamine isn’t moved out of its signaling zone. “That’s the calling card of MDPV. That’s also the calling card of a very addictive substance.”

Bath salts containing two other compounds, mephedrone and methylone, take a different tack, Baumann’s group reported in 2012 in Neuropsychopharmacology. Similar in size to dopamine, these drugs can slip inside the carrier molecule, forcing it to spit dopamine into the space between neurons. In Baumann’s studies, mephedrone and methylone didn’t increase dopamine levels as much as MDPV did. But, he says, “these molecules enter cells, are accumulated inside and cause neurotoxic effects.”

Stoner behavior
There haven’t been any controlled trials of designer drugs in humans in the United States and very few in other countries. So researchers observe how the drugs alter the behavior of mice, which can help the DEA get the drugs off the street. “These models cannot prove that the drug will produce a high in humans, but they are the best we have,” says Wiley, of RTI International.

So how can she tell a mouse is stoned? Wiley injects synthetic cannabinoids into mice and looks for sluggishness, pain tolerance and lowered body temperature. Though synthetic cannabinoids have quite different chemical structures than THC (the active ingredient in marijuana), they evoke similar rodent responses. The mice sit in one spot without moving and are slow to flick their tail away when a hot light shines on it. Wiley also tests whether the mice wasted on synthetic cannabinoids act the same way they do when stoned on THC.

“The DEA needs information showing that the substances have effects similar to those of marijuana in order to work with other government agencies to ban the compounds,” Wiley says. The agency used her behavioral and chemical profiles of synthetic cannabinoids to close down a spice-selling shop in Duluth, Minn., she says.

Adam Halberstadt and Mark Geyer, psychopharmacologists at the University of California, San Diego, ran a similar battery of tests to confirm the hallucinogenic properties of NBOMes. When hallucinating, mice start quickly twitching their heads, the researchers reported last year in Neuropharmacology. Halberstadt speculates that the animals were hallucinating that they were being touched or getting wet.

The 25I-NBOMe, which sent Suzuki’s patient into a suicidal frenzy, is especially potent and also made the mice hyperactive, Halberstadt says.
NBOMes chemically resemble mescaline, a compound found in the peyote cactus. They don’t spike dopamine levels and aren’t addictive. But an overdose can prompt paranoia, seizures, a racing heart or high blood pressure. NBOMes masquerade as extra serotonin, a molecule that plays many roles in the brain, some related to mood, aggression and sensitivity to pain.

NBOMes can be dissolved and sold on paper blotters. Unfortunately, this means NBOMes are often sold as LSD. “People know that they can sell this as LSD and make more profit than they would by selling these compounds as what they really are,” says Halberstadt. “They’re being sold as something that is believed to be safe, but these don’t have the safety margin that LSD does.”

Massive doses of LSD may cause panic reactions known as bad trips, but they are unlikely to kill a person. “People know how to take LSD. It’s been around for a long time,” says Josh Elmore, a pharmacologist in Baumann’s lab. But with NBOMes, “If the person making the blotter puts a little bit too much, people die,” he says.

This lack of consistency in dosing is not limited to NBOMes. Spice is typically sprayed on plant leaves (often from the herb marshmallow) before being packaged and sold. “It’s very arbitrary and it’s up to whoever’s doing the formulation and adding the drug to that plant material,” says the DEA’s Jill Head.

This unpredictability extends to other modes of spice, which can also be vaped via e-cigarette. One of the problems is that synthetic cannabinoids dissolve poorly in the vaping liquid. The drug may start to crystallize over time, says Wiley. “If you’re down to the last little dregs of your e-liquid and it’s mostly these pieces of the chemical that have fallen out of solution, but you stuff that in your e-cigarette, what you might end up with is a very, very large dose,” she says.

A chemical Hydra
Trying to profile and ban designer drugs is like fighting Greek mythology’s many-headed Hydra, which sprouted more heads as soon as one was sliced off. The DEA can declare drugs temporarily illegal as they appear. This process, called emergency scheduling, gives the agency a chance to evaluate the drug before officially labeling it illegal. But drugmakers “can tweak substances and come up with new ones faster than the regulatory process allows us to schedule them,” says Barbara Carreno, a DEA spokesperson.

The drugs are made in China, India and Pakistan by chemical companies, Baumann says. “The people that are doing this, they’re probably Ph.D.-level chemists that are mining the medical literature for these structural templates. This isn’t the Hell’s Angels brewing stuff in a bathtub; this is a very sophisticated operation.”

Where the drugs migrate when they leave Asia can vary. “Early on in this trend of emerging synthetics, Europe was a barometer for us,” says Jeff Comparin, a forensic chemist at the DEA. When the drugs appeared in Europe, the United States would have advanced warning of about six months. “More recently, we think that we’re encountering new drugs in the United States first.”

A small kernel of self-regulation may come from within the drug-user communities — at least for NBOMes. In the last year especially there’s been a growing chorus among both users and vendors that selling NBOMes as LSD will be the new drug’s downfall, Suzuki says.

In the meantime, Baumann and his cohorts continue to profile the dizzying array of new drugs as they emerge. There’s no sign that unscrupulous chemists will stop flexing their creative muscles anytime soon. “I hope I’m wrong,” Baumann says, “but it doesn’t look like there’s any end to it. It’s essentially an infinite number of possibilities.”

This article appears in the May 16, 2015, issue with the headline, “Drugs by design: Corrupt chemists tweak compounds faster than law enforcement can call them illegal.”

Children with autism excel at motion detection test

On a test of visual perception, children with autism perceive moving dots with more clarity than children without the disorder. The results, published in the May 6 Journal of Neuroscience, reveal a way in which children with autism see the world differently.

When asked to determine the overall direction of a mess of dots moving in slightly different directions, children with autism outperformed children without the disorder. Other tests of motion detection didn’t turn up any differences. The results suggest that children with autism may be taking in and combining more motion information than children without autism, says study coauthor Catherine Manning of the University of Oxford. This heightened ability may contribute to feelings of sensory overload, the researchers suggest.

Stimulating nerve cells stretches time between thinking, doing

A zap to the head can stretch the time between intention and action, a new study finds. The results help illuminate how intentions arise in the brain.

The study, published in the May 6 Journal of Neuroscience, “provides fascinating new clues” about the process of internal decision making, says neuroscientist Gabriel Kreiman of Harvard University. These sorts of studies are bringing scientists closer to “probing some of the fundamental questions about who we are and why we do what we do,” he says.
Figuring out how the brain generates a sense of control may also have implications for people who lack those feelings. People with alien hand syndrome, psychogenic movement disorders and schizophrenia can experience a troubling disconnect between intention and action, says study coauthor Biyu Jade He of the National Institutes of Health in Bethesda, Md.

In the study, the researchers manipulated people’s intentions without changing their actions. The researchers told participants to click a mouse whenever the urge struck. Participants estimated when their intention to click first arose by monitoring a dot’s position on a clockface.

Intention to click usually preceded the action by 188 milliseconds on average, the team found. But a session of transcranial direct current stimulation, or tDCS, moved the realization of intention even earlier, stretching time out between awareness of intention and the action. tDCS electrodes delivered a mild electrical zap to participants’ heads, dialing up the activity of carefully targeted nerve cells. After stimulation, intentions arrived about 60 to 70 milliseconds sooner than usual. tDCS seemed to change certain kinds of brain activity that may have influenced the time shift, EEG recordings suggested.

The results highlight how thoughts and intentions can be separated from the action itself, a situation that appears to raise thorny questions about free will. But these tDCS zaps didn’t change the action outcome or participants’ feelings of control, only the reported timing of a person’s conscious intention.

How did Earth get its water?

Earth — a planet of oceans, rivers and rainforests — grew up in an interplanetary desert.

When the solar system formed about 4.6 billion years ago, shards of calcium- and aluminum-rich minerals stuck together, building ever-larger pebbles and boulders that smashed together and assembled the rocky planets, including Earth.

But Earth’s signature ingredient was nowhere to be found. Heat from the young sun vaporized any ice that dared to come near the inner planets. Earth’s relatively feeble gravity couldn’t grab on to the water vapor, or any other gas for that matter. And yet, today, Earth is a planet that runs on H2O. Water regulates the climate, shapes and reshapes the landscape and is essential to life. At birth, humans are about 78 percent water — basically a sack of the wet stuff.
To get water, Earth had to have help from somewhere else.

Researchers recently found traces of Earth’s aquatic starter kit locked away inside several meteorites, chunks of rock that fell to the planet’s surface. Those meteorites were a gift from Vesta, the second largest body in the asteroid belt between Mars and Jupiter. Vesta is thought to have formed earlier than Earth, roughly 8 million to 20 million years after the start of the solar system. (Earth needed 30 million to 100 million years to pull itself together.)

Well before the rocky planets formed, recent research suggests, ice-infused asteroids were forged beyond Jupiter and subsequently swarmed the inner solar system. These space rocks delivered water to Vesta and to Earth after being hurled at our planet by the gravity of Jupiter and Saturn. Whether the giant planets were a help or a hindrance is anybody’s guess. But if what happened here can happen anywhere, then water might be prevalent on other worlds, giving life a good chance of thriving throughout the galaxy.

Comets vs. asteroids
For decades, researchers have debated whether comets or asteroids delivered Earth’s water. At first glance, comets seemed a likely source. Originating beyond the orbit of Neptune, comets are the deep-freeze storage units of the solar system. They hold a lot of ice that has been locked away within their interiors since the formation of the solar system. Some comets are occasionally thrown inward after a close brush with a planet or passing star. It makes sense that, during the chaos of the early solar system, Earth would have been pummeled with comets, bringing plenty of water to fill the oceans.

In recent years, however, the comet hypothesis has lost favor. “It looks like comets are pretty much out,” says cosmochemist Conel Alexander of the Carnegie Institution for Science in Washington, D.C. Most of the comet water tested so far doesn’t match that of Earth’s oceans. Plus, it’s incredibly difficult to bring a comet toward Earth, much less a whole slew of them. “It just shouldn’t be part of the discussion anymore,” he says.

Part of the problem lies in a subtle chemical difference between water on Earth and water in most comets. Water is a simple molecule resembling a pair of Mickey Mouse ears: two hydrogen atoms grab a single oxygen atom. But sometimes deuterium, a slightly heavier version of hydrogen, weasels its way into the mix. The nucleus of a deuterium atom contains one proton and one neutron; in hydrogen, the proton stands alone. On Earth, only about 156 out of every 1 million water molecules contain deuterium.
Researchers have long used the relative amount of deuterium compared with hydrogen — known as the D/H ratio — to trace water back to where it originated. At colder temperatures, deuterium starts to show up in ice more frequently. So bodies that formed in the frigid backwaters of the solar system, such as comets, should be enriched in deuterium, whereas the water vapor that swirled around the infant Earth should have little to none.
Most comets appear to follow that logic; their D/H ratio is typically about twice what has been measured on Earth.

Two comets, however, threw a curveball at scientists who had counted out comets as the source of Earth’s water. In 2010, researchers used the Herschel space telescope to measure the D/H ratio of comet 103P/Hartley 2. They reported that 103P’s water nearly matched that found on Earth. Observations of comet 45P/Honda-Mrkos-Pajdušáková three years later also found abnormally low D/H ratios. Suddenly one, possibly two, comets were carrying Earthlike water.

Jupiter’s pull
Both of these comets are part of a community known as Jupiter family comets. They originated in the Kuiper belt, the ring of icy debris beyond Neptune where Pluto lives. The gravity of first Neptune and then Jupiter gradually nudged these comets into relatively short orbits that bring them closer to the sun. All previous D/H measurements were of comets that hail from the far more distant Oort cloud, a shell of ice fragments that envelops the solar system. Comets 103P and 45P suggested that researchers may have been hasty in dismissing all comets as Earth’s water source. Perhaps just the Jupiter family comets were responsible.

But then in 2014, the European Space Agency’s Rosetta probe arrived at Comet 67P/Churyumov–Gerasimenko, another Jupiter family comet. As the spacecraft sidled up to the comet, it sampled the water streaming from the comet body and found 67P’s D/H ratio to be staggeringly high — more than three times that of Earth’s oceans (SN: 1/10/15, p. 8).

“Each new comet measurement is giving us a different picture,” says Karen Meech, a planetary scientist at the University of Hawaii in Honolulu. The Rosetta results show that even among a single family of comets, there is incredible diversity in water composition. “Comets formed over a huge range of distances, so it’s no surprise that there’s a huge range in D/H,” she says.

But even if some comets have an Earth-like D/H ratio, it’s still really hard to get comets to hit our planet in the first place. “Any comet that’s going to bash into Earth has to get past this really big linebacker of Jupiter,” says planetary scientist Sean Raymond of the Laboratoire d’Astrophysique de Bordeaux in France. Jupiter has a tendency to take comets that come too close and fling them out of the solar system. The few that do end up on Earth-crossing orbits don’t stay there for long.

“The comet only has a certain number of tries to get in close and either hit Earth or get scattered on to another orbit,” Raymond says.

So Jupiter’s gravity may be too big a hurdle for comets to overcome. But it may be just the ticket for flinging asteroids at the inner planets.

A more ‘tack’-ful approach
In 2011, a team of researchers including Raymond were tackling a different problem: Why is Mars so small? There should have been plenty of raw material available 4.6 billion years ago to turn Mars into a planet closer in size to Venus or Earth. But Mars is just about half Earth’s diameter and about one-tenth its mass. One possible explanation is that something prematurely robbed the nascent Red Planet of its building blocks.

One solution, known as the Grand Tack model, describes a solar system far less sedate than the one we inhabit today (SN Online: 3/23/15). In the Grand Tack scenario, Jupiter and Saturn stride back and forth across the solar system like schoolyard bullies, hurling rocks at and stealing food from the other planets. The gas that encircled the sun dragged Jupiter and then Saturn inward. Once Jupiter arrived at about the current orbit of Mars, a gravitational tug from Saturn flung both back out from where they came (the “tack” in “Grand Tack”).  Jupiter’s encroachment on the inner solar system carved a gap in the debris field from which the rocky planets were forming, depriving Mars of raw ingredients.
Story continues below slideshow


Along with Earth, a couple of dwarf planets and several moons have shown evidence of water, in one form or another. Their potential to support life varies.
The same planetary tango that robbed Mars of resources might also explain how icy asteroids pummeled Earth. As Jupiter and Saturn wandered back out, their gravity latched on to asteroids that formed beyond the snow line — the boundary beyond which temperatures are low enough for ice to form — and flung them inward. About 1 percent of these ice-infused boulders, known as C-type asteroids, were dropped into the outer regions of the asteroid belt. But for every C-type asteroid relocated to the belt, at least 10 were sent careening into the region where the rocky planets were materializing.

This bombardment of asteroids a few million years after the start of the solar system could have easily delivered enough ice — locked inside the rocks, safe from the sun’s heat — to account for Earth’s oceans, computer simulations indicate. Water makes up to about 20 percent of the mass of some of these asteroids. On Earth, despite having more than 70 percent of its surface blanketed in blue, water accounts for only 0.023 percent of the planet’s mass. Compared with some asteroids, Earth is positively parched.

The Grand Tack nicely explains the formation of Mars, the layout of the asteroid belt and the delivery of water to Earth via icy asteroids. But Raymond stresses that it’s just one way to match all the data. “It’s an evolution of thinking,” he says. “It’s not meant to be a final solution.”

The same D/H ratio that exonerated comets is now pointing a finger at these asteroids. In 2012, Alexander and colleagues concluded in the journal Science that the bulk of Earth’s water arrived via bodies similar to a class of meteorites known as CI carbonaceous chondrites. Researchers think that these meteorites, which were knocked off asteroids that formed beyond Jupiter, are among the oldest objects in the solar system.

Alexander’s research, along with that of many others, builds a strong case for a chemical match between Earth’s water and chondrites’ water. But it doesn’t address when the water arrived. Brown University geologist Alberto Saal argues that part of the answer lies on the moon.

Story continues below graphic
The bounty of lunar samples brought to Earth by Apollo astronauts included volcanic glass hauled in during the Apollo 15 and 17 missions. The glass formed from rapidly cooling magma that was spat out from the moon’s interior long ago. In 2013, Saal and colleagues reported in Science that the D/H ratio of water trapped within the glass matched that measured in both Earth’s oceans and Alexander’s carbonaceous chondrites (SN: 6/29/13, p. 8). Saal’s findings suggest two things: Earth and the moon have a common source of water and the water was already here when the moon formed.

The moon started with a literal bang. A planet the size of Mars is thought to have smashed into Earth toward the end of our planet’s formation. The collision blasted part of Earth, as well as the unfortunate interloper, into a ring of vaporized rock that encircled Earth before sticking together to build the moon (SN: 7/12/14, p. 14). Water must have been present at the time of impact for it to be sealed into the moon, Saal notes, or it at least arrived before the moon’s surface had time to cool and solidify. This puts water near Earth about 150 million years after the start of the solar system. But based on the moon data alone, we can’t say how much earlier, says Sune Nielsen, a geologist at the Woods Hole Oceanographic Institution in Massachusetts.
To narrow in on a more precise time for water’s arrival, researchers have turned to the asteroid Vesta. Or, more specifically, meteorites nicked off Vesta after the asteroid got whacked by another space rock. Woods Hole geologist Adam Sarafian, Nielsen and colleagues analyzed small amounts of water trapped within minerals of apatite locked inside a sample of Vesta meteorites. The team reported last fall in Science that the D/H ratio of the meteorites’ water matched Earth’s. That discovery implies that whatever delivered Vesta’s water brought along Earth’s as well and that this water had to have arrived before Vesta finished forming (SN Online: 11/1/14).

That finding pushes the influx of water back, possibly as early as 8 million years after the start of the solar system. This is the oldest stockpile of water ever dated in the solar system, Nielsen says. These observations place water in the inner solar system well after Jupiter and Saturn were on the prowl, lobbing asteroids around the solar system.

Nailing down how and when water arrived at Earth is about more than just understanding how our planet was built. “If you have to have some sort of external delivery mechanism for getting water to terrestrial planets,” says Alexander, “it becomes harder to make a habitable planet.” Rocky planets forming around other stars will face the same problem that Earth faced. These planets in the habitable zones of their stars, while able to support liquid water on their surfaces, develop in dry environments and need to have ice sent in from farther out. Did Earth get lucky by having Jupiter and Saturn as neighbors, or are there other ways to move water around?

Just because Earth formed one way doesn’t mean all habitable planets must follow the same path. “I would be cautious,” Nielsen says, about saying that gas giants are the only way to bring water to rocky planets.

In fact, gas giants may even be a hindrance. “Jupiter and Saturn just screw things up,” says Raymond. Their gravity is strong enough that they tend to kick asteroids and comets right out of the solar system. If Jupiter and Saturn didn’t exist, he notes, Earth’s gravity could have stolen 10 times as much water from the outer edge of the asteroid belt. In the absence of giant planets, water delivery could happen naturally as planets pull in debris from different parts of the solar system. Recent observations from the Kepler space telescope suggest that planets the size of Jupiter are relatively uncommon around other stars. Perhaps most habitable planets do just fine on their own.

If that’s the case, then maybe the galaxy is teeming with ocean worlds waiting to be discovered. “From my point of view,” Raymond says, “having water on a planet like Earth is an everyday occurrence.”

WET AND WILD Earth may have Jupiter and Saturn to thank for sending it water way back when. The two gas giant planets did a gravitational dance with the sun and each other that sent them hurling in then back out to the outer solar system. In reaction, a bunch of icy asteroids shot into the inner solar system, pummeling early Earth and bringing it water, as shown in this animation. Credit: Drawings by Helen Thompson; Images courtesy of NASA; Narrated and produced by Helen Thompson and Ashley Yeager

This article appears in the May 16, 2015, issue with the headline, “Water, water everywhere: Every bit of Earth’s H2O was delivered by space rocks, but which ones?”

Editor’s note: This story was corrected on May 18, 2015. A caption incorrectly referred to hydrogen molecules, instead of hydrogen atoms. The Water Here and There slideshow was corrected and updated on May 20.