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Gisela Giardino, Wikimedia Commons // CC BY-SA 2.0
Gisela Giardino, Wikimedia Commons // CC BY-SA 2.0

It Turns Out That Single-Celled Organisms Are Having Sex Too

Gisela Giardino, Wikimedia Commons // CC BY-SA 2.0
Gisela Giardino, Wikimedia Commons // CC BY-SA 2.0

So much for the stereotype of the chaste, pious diatom. (Wait. Is that not a stereotype?) Scientists examining tiny single-celled organisms say we've been wrong to assume they* lead lives of quiet, sexless desperation. The researchers described their microscopically racy findings in the journal PLOS One.

The tiny specks called diatoms are neither plants nor animals but somewhere in between; they're algae. There are more than 200,000 species living in the water all over the world, each with its own unique and beautiful frustule, or hard silica scaffolding.

Microscope image of Stephanopyxis grunowii frustule fossil.
Anatoly Mikhaltsov, Wikimedia Commons // CC BY-SA 4.0

To date, scientists have sequenced the genetic code of only two diatoms: the peapod-shaped Phaeodactulum tricornutum and the round, or centric, Thalassiosira pseudonana. The genes of T. pseudonana contained some sex-related code, but researchers believed it was vestigial, like our wisdom teeth or the wings of a kiwi bird.

"Everybody said Thalassiosira pseudonana was asexual, because they'd never seen anything else," corresponding author Kimberly Halsey of Oregon State University said in a statement. "The general thinking was that it just lost the ability or need to go through sex."

Not for lack of trying on our part. Previous experimenters have tried all kinds of things to get the little specks to get busy, from turning off the lights to adding more salt to the water.

"Lab efforts to induce sex in centric diatoms have ranged from sweet talk to torture," Halsey said. These efforts weren't entirely fruitless; once in a while, the diatoms might show some interest. But it wasn't clear why, or if the tiny organisms would do it on their own.

Halsey and her colleagues decided to take another close look at T. pseudonana. They went back over its genome, studying any gene that could be related to sexual activity, then stared long and hard at the diatoms themselves.

What they found surprised them. The diatoms had genes that would allow them to differentiate—that is, to become one sex or another. Lead author Eric Moore says he was startled by this realization.

"In fact, I was convinced my cultures were contaminated before I realized what was actually going on," he said. 

Moore, Halsey, and their colleagues also discovered the secret to getting T. pseudonana in the mood: a little aphrodisiac known as ammonia.

While many of us know ammonia as an awful-smelling cleaning agent, it's not hard to find it in the wild, as a component of urine and other waste. Exposing the diatoms to ammonia was all it took to get the cells to start making eggs and sperm.

The authors say the diatoms may be regularly soaking in ammonia and, consequently, getting sexy.

"Our discoveries solve two persistent mysteries that have plagued diatom researchers," Halsey said. "Yes, they have sex, and yes, we can make them do it."

 

*The single-celled organisms, not the scientists. The sex lives of the latter are none of our business.

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NOAA, Wikimedia Commons // Public Domain
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Animals
Watch the First-Ever Footage of a Baby Dumbo Octopus
NOAA, Wikimedia Commons // Public Domain
NOAA, Wikimedia Commons // Public Domain

Dumbo octopuses are named for the elephant-ear-like fins they use to navigate the deep sea, but until recently, when and how they developed those floppy appendages were a mystery. Now, for the first time, researchers have caught a newborn Dumbo octopus on tape. As reported in the journal Current Biology, they discovered that the creatures are equipped with the fins from the moment they hatch.

Study co-author Tim Shank, a researcher at the Woods Hole Oceanographic Institution in Massachusetts, spotted the octopus in 2005. During a research expedition in the North Atlantic, one of the remotely operated vehicles he was working with collected several coral branches with something strange attached to them. It looked like a bunch of sandy-colored golf balls at first, but then he realized it was an egg sac.

He and his fellow researchers eventually classified the hatchling that emerged as a member of the genus Grimpoteuthis. In other words, it was a Dumbo octopus, though they couldn't determine the exact species. But you wouldn't need a biology degree to spot its resemblance to Disney's famous elephant, as you can see in the video below.

The octopus hatched with a set of functional fins that allowed it to swim around and hunt right away, and an MRI scan revealed fully-developed internal organs and a complex nervous system. As the researchers wrote in their study, Dumbo octopuses enter the world as "competent juveniles" ready to jump straight into adult life.

Grimpoteuthis spends its life in the deep ocean, which makes it difficult to study. Scientists hope the newly-reported findings will make it easier to identify Grimpoteuthis eggs and hatchlings for future research.

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Penn Vet Working Dog Center
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Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

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