DNA Analysis Reveals Why ‘Water Bears’ Are the World’s Toughest Animals


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DNA Analysis Reveals Why ‘Water Bears’ Are the World’s Toughest Animals

Diane Nelson, a Tardigrade researcher who works in Great Smoky Mountains National Park, used a scanning microscope to take this 3-D image of a Tardigrade.

Credit: NPS/Diane Nelson

Tardigrades, also known as water bears, are less than a fraction of an inch in length, yet they are believed to be Earth’s toughest, hardiest animals. They are virtually indestructible. Tardigrades have the ability to withstand complete dehydration. Once desiccated, they have been frozen in blocks of ice, exposed to radiation, and sent into the vacuum of space, and yet they still usually spring back to life when water becomes available again.

New genetic research, published in the journal PLOS Biology, reveals how tardigrades achieve such resurrections after drying to a crisp. The authors now even believe that alien life forms could possess this remarkable ability.

“If life exists on other planets, and it is water-based, then those organisms that live out of water will evolve to resist extreme events, including the threat of drying out,” said co-author Mark Blaxter of the University of Edinburgh’s Institute of Evolutionary Biology.

He added that the ability to undergo anhydrobiosis — the desiccated, dormant state — “has evolved multiple times on Earth, so I am sure it will have evolved on other living planets.”

Blaxter and his colleagues took a clever approach to unravel the scientific secrets behind anhydrobiosis in tardigrades.

The scientists re-sequenced and reassembled the genome of Hypsibius dujardini, a tardigrade that can only undergo desiccation after extensive pre-exposure to drying conditions. They then compared the tiny animal’s DNA with that of Ramazzottius varieornatus, a related species with tolerance to rapid desiccation.

The researchers then looked at a particular set of genes, the so-called HOX genes, which establish the nose-to-tail pattern in embryos. There are usually about ten different HOX genes in animals, but tardigrades are missing five. Nematodes (roundworms) lack these same five genes.

RELATED: Microscopic Tardigrade ‘Water Bears’ Will Be the Last Survivors on Earth

“This could be because they share a common ancestor with tardigrades, and the loss happened in this ancestor,” Blaxter said. “Alternatively, it could be that the loss is associated with both groups becoming miniaturized, and these ‘middle’ HOX genes are the ones that are the easiest to lose.”

He added that the shared genetic loss could also simply be due to independent evolution. Because of these remaining questions, scientists continue to debate whether or not tardigrades are more closely related to nematodes or to arthropods — insects, spiders, and crustaceans.

By asking which genes were turned on during tardigrade anhydrobiosis, the scientists could identify sets of proteins, which appear to replace the water that tardigrade cells lose, thus helping to preserve the microscopic structures until water is available again.

Arakawa explained that all cells contain around 60–80 percent water when they are active, including human cells.

The key proteins that they identified are highly soluble. They dissolve in water that, due to surface tension, clings to and surrounds intracellular molecules within tardigrades. Like a microscopic protective coating, they prevent the cells from denaturing when the animal otherwise desiccates.

Arakawa added that tardigrades also possess additional genes that protect their DNA from damage. Because these small animals lack stress-sensing pathways, their cells do not usually die out when damaged. Instead, the identified proteins try to make repairs, and are often successful in doing so.

Due to these abilities, scientific consensus holds that tardigrades could be Earth’s last survivors. Such resilience is unexpected in a tiny creature that seems to exist in the slow lane.

“Tardigrades are slow walkers, and are not really aggressive animals,” Arakawa explained. “Therefore, they tend to lose competitions for food, or can become prey in a diversified ecosystem. But tardigrades fled to their own niche, where only tardigrades can survive, so paradoxically, tardigrades presumably acquired their extreme survival abilities due to their ecological incompetence.”

RELATED: Tardigrade ‘Water Bear’ Dries to a Crisp and Then Comes Back to Life

Arakawa and his colleagues can envision a day when enzymes, vaccines, human organs, tissues, and cells could be preserved in a state of anhydrobiosis instead of by liquid-nitrogen-based freezing.

“Some people have suggested that tardigrades could somehow travel through space to seed other planets with Earth-derived life,” Baxter said. “That obviously didn’t happen on Earth, as only some tardigrades are able to do anhydrobiosis, and tardigrades are derived from other, more ancient forms.”

While it is doubtful that tardigrades are somehow hurtling through space now, these amazing animals continue to captivate researchers. Blaxter and Arakawa, for example, have been studying them with awe and admiration for years.

Blaxter, one of the few tardigrade genomics experts in the world, reminisced that his scientific career was sewn when, as a child, he was gifted with an animal encyclopedia by his parents.

“I especially pored over the weird and wonderful animals that were so beyond what I had seen with my own eyes,” he recalled.

When, many years later, one of his Ph.D. students suggested that he study tardigrades, a lightbulb went off.

“We haven’t looked back,” Blaxter said.

Originally published on Seeker.

 

Moving Nose to Tail, Shrew ‘Conga Line’ Shimmies Online


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Moving Nose to Tail, Shrew ‘Conga Line’ Shimmies Online

A caravan of shrews

Credit: Alamy

A creepy, crawly video of tiny critters holding each other’s tails and scurrying across the ground like a furry centipede has captured the internet’s attention.

Called “The NOPE train,” the video has garnered nearly 3 million views since it was posted to Imgur on Monday (July 24). Commenters got creative, calling the furry unit “the human centipede: mice edition,” a “rat king in the making” and a “fluffy snake.” One user wryly posted, “The caboose is a bit wobbly.”

At least two commenters got the animal right: They’re shrews. And not just any shrews — that fuzzy conga is a mother shrew leading her babies in a train, known as a caravan, according to Cynthia Alvarado, a clinical veterinarian at the Jackson Laboratory in Bar Harbor, Maine. [The World’s 6 Smallest Mammals]

Here’s how the caravan works: The mother shrew heads the line, and each preceding baby shrew bites down on the base of the tail belonging to the shrew in front of it. Then, with Mom in the lead, the shrews can travel together in a fairly ordered procession.

The NOPE train…

Shrews typically form these caravans when their nest is disturbed and the mother decides to evacuate her young to safety, according to the Mammal Society, a charity in the United Kingdom that advocates science-led mammal conservation. Caravans may also be used to encourage shrew pups to explore their surroundings, the society noted.

Female shrews usually have three or four litters between May and September, with each litter consisting of about five to seven pups. Each litter can have two or three fathers, the Mammal Society reported.

Another video of a shrew caravan, posted by YouTube user Вот так Вот and called “Мыши идут строем,” which translates to “Mice go in line,” shows the bizarre phenomenon as well.

Given that Вот так Вот and several Imgur posters thought the critters were rodents, it’s important to note that shrews are in an entirely different taxonomic order.

“Mice are in the order Rodentia, and shrews are in the order Eulipotyphla, which includes animals likes moles and hedgehogs,” Alvarado said.

Original article on Live Science.

The Evil Eye: A Closer Look


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The Evil Eye: A Closer Look

The evil eye is a specific type of magical curse. It is believed to cause harm, illness and even death.The evil eye is a specific type of magical curse. It is believed to cause harm, illness and even death.

Credit: Vasilchenko Nikita | Shutterstock

Everyone gets a dirty look now and then, and we usually think little of it (especially if we deserved it). For most of us it is soon shrugged off, but in many places belief in “the evil eye” is taken very seriously, and requires immediate action to avoid harm.

The evil eye is a human look believed to cause harm to someone or something. The supernatural harm may come in the form of a minor misfortune, or more serious disease, injury — even death. Folklorist Alan Dundes, in his edited volume “The Evil Eye: A Casebook” notes that “the victim’s good fortune, good health, or good looks — or unguarded comments about them — invite or provoke an attack by someone with the evil eye … Symptoms of illness caused by the evil eye include loss of appetite, excessive yawning, hiccups, vomiting and fever. If the object attacked is a cow, its milk may dry up; if a plant or fruit tree, it may suddenly wither and die.”

The evil eye is also said to cause a number of other maladies including insomnia, fatigue, depression and diarrhea. In many places, disease is considered a magical as well as a medical issue, and the reason a given person succumbs to a malady may be attributed to a curse instead of random chance or exposure to a virus. It can even affect objects and buildings: The evil eye cast upon a vehicle may break down irreparably, while a house so cursed may soon develop a leaky roof or an insect infestation. Just about anything that goes wrong may be blamed on the power of the evil eye.

The evil eye is well known throughout history. It is mentioned in ancient Greek and Roman texts, as well as in many famous literary works, including the Bible (such as Proverbs 23:6: “Eat thou not the bread of him that hath an evil eye, neither desire thou his dainty meats”) the Koran and Shakespeare’s plays. Though belief in the evil eye is widespread, it is not universal. A 1976 cross-cultural survey by folklorist John Roberts found that 36 percent of cultures believed in the evil eye.

The evil eye is essentially a specific type of magical curse, and has its roots in magical thinking and superstition. Let’s say that a person experiences bad luck, ill health, accident, or some unexplained calamity — perhaps a drought or an infectious disease. Before science could explain weather patterns and germ theory, any bad event for which there was not an obvious cause might be blamed on a curse. Curses, including the evil eye, are an answer to the age-old question of why bad things happen to good people.

Eyes are said to have special powers; they are said to be the gateway to a person’s soul. Shifting eyes are said to subtly betray liars, while a steady gaze may be endearing or menacing depending on the circumstances. Eye contact can create an intensely personal connection, whether between lovers or superiors and subordinates. Glaring or intense staring can convey power and authority over another. And of course, actors use their eyes to convey a wide range of emotions, including love, hate, disgust, boredom, scorn, surprise and envy. In fact it is this last emotion — jealousy — that underlies the evil eye’s cultural association with magic.

Belief in the power of the eyes is so powerful that any eye affliction has come to suggest evil and bad luck. People who are cross-eyed, have uncontrollable eye twitches or spasms (a condition called blepharospasm), or who merely have a prominent squint have been shunned and feared as provoking bad luck, especially among those who work in dangerous occupations such as fishing and mining. Similarly, those with unusually close-set eyes or eyes of different colors were often suspected of having the evil eye.

Babies and children are said to be especially susceptible to harm from the evil eye, and in many countries, including Greece, Romania, and India, praising a child publicly is sometimes considered taboo, for the compliment will draw the attention of the evil eye. In order to ward off the evil eye, parents of a thoughtlessly praised child may ask the person who gave the compliment to immediately spit in the child’s face. Because the momentarily exalted youngster has been brought down a peg, any harm by the evil eye is unnecessary; this spittle salve is harmless yet insulting enough to negate the compliment.

Who has the evil eye? Maybe you do. Many believe that bad intention is not necessary, and that some people can cast an evil eye without even knowing it. If one person is believed to have the evil eye, other members of his or her family are often treated with suspicion — and any children are assumed to have the curse as well.

The best way to deal with the evil eye is to avoid it in the first place. The method varies by culture, geographic region, and personal preference. In Latin America the evil eye is known as “mal de ojo,” and belief in it is especially widespread in rural areas. In Puerto Rico, for example, newborns are often given a good luck charm called an azabache to protect them from the evil eye.

Amulets can be worn to deter the evil eye, often using the color blue (symbolizing heaven or godliness) and an eye symbol. Charms, potions and spells can also be prepared; garlic can be used to deter the evil eye, and some believe that just saying the word “garlic” offers protection.

Often those who believe they have been harmed by the evil eye will seek out shamans, witch doctors, psychics or other spiritual healers to remove the curse. There are several ways to cure mal de ojo; one traditional method from Mexico involves the use of a raw egg. The egg, a universal symbol of purity and birth, is said to absorb evil energies as it passes over the forehead and prone body of the victim. The egg is then broken over a bowl of water and the resulting forms closely examined for any unusual shapes. An oval or eye shape seen in the yolk or whites is said to indicate that the evil eye’s power has been successfully removed from the victim. Some claim that the gender of the person who cast the evil eye can be determined from the shapes.

It is tempting to view the evil eye as an ancient, discredited belief that plays no role in our 21st-century world. Instead, as folklorist Dundes notes, we “should keep in mind that the evil eye is not some old-fashioned superstitious belief of interest solely to antiquarians. The evil eye continues to be a powerful factor affecting the behavior of countless millions of people throughout the world.”

Though belief in the evil eye can be a harmless superstition, it can also be dangerous in some circumstances. Any time one person believes that another has harmed them — whether naturally or supernaturally, intentionally or accidentally — there is the potential for deadly retribution. Like other accused witches and sorcerers over the centuries, many people have been attacked, beaten, and killed for casting an evil eye.

Canaanites Live: DNA Reveals Fate of Biblical People


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Canaanites Live: DNA Reveals Fate of Biblical People

A burial jar containing the remains of an ancient inhabitant of the Canaanite city of Sidon. This individual was one of five whose DNA was sequenced to reveal the ancestry of the Canaanites.

Credit: Dr. Claude Doumet-Serhal/The Sidon Excavation

The people of modern-day Lebanon can trace their genetic ancestry back to the Canaanites, new research finds.

The Canaanites were residents of the Levant (modern-day Syria, Jordan, Lebanon, Israel and Palestine) during the Bronze Age, starting about 4,000 years ago. They’re best known from the Old Testament of the Bible, in which they’re described as the cursed descendants of Canaan, blighted by God because Canaan’s father dishonored his own father, the patriarch Noah. The Canaanites were often in conflict with the Israelite tribes that wrote the Hebrew Bible. In fact, the Book of Deuteronomy features Yahweh (God) ordering the Canaanites to be exterminated.

In part because the Canaanites kept their records on easily degradable papyrus rather than clay, little is known about their side of the story. But now, ancient DNA reveals that the Canaanites were the descendants of Stone Age settlers and the ancestors of the Lebanese. [Biblical Battles: 12 Ancient Wars Lifted from the Bible]

“Canaanite ancestry was widespread in the region,” study researchers Marc Haber and Chris Tyler-Smith of the Wellcome Trust Sanger Institute in the United Kingdom wrote in an email to Live Science, “and several groups who were probably culturally different shared the same ancestral background.”

Haber, Tyler-Smith and their colleagues extracted ancient DNA from the bones of five Canaanites who died in the ancient city of Sidon (an area now in Lebanon). The skeletons dated from between 3,750 and 3,650 years ago. The researchers then compared the genetic sequences of these ancient Canaanites with those of 99 modern Lebanese people, as well as with ancient DNA sequences of more than 300 other people from an ancient DNA database.

A young person’s body buried in the Canaanite city of Sidon more than 3,500 years ago.

Credit: Dr. Claude Doumet-Serhal/The Sidon Excavation

The findings revealed broad overlap between Canaanite genetics and the sequences of modern-day people from Lebanon. Researchers even found some ancient gene variations that suggested the Canaanites probably had similar coloration in skin, eyes and hair as Lebanese people do today. It was surprising, Haber and Tyler-Smith said, to find such continuity in the Canaanite line, given all of the conquests and expansions into the Middle East from outside groups since the Bronze Age.

The Canaanites themselves descended from Stone Age settlers who mixed with newcomers from what is now Iran about 4,000 to 5,000 years ago, the researchers said. This mixture could be explained by the expansion of the Akkadian Empire, a Mesopotamian empire that peaked around that time, the researchers wrote.

The excavation of Sidon, an ancient Canaanite city in what is now Lebanon.

Credit: Dr. Claude Doumet-Serhal/The Sidon Excavation

After the Bronze Age, the Canaanites did mix a little bit with their neighbors. Modern-day Lebanese populations are largely Canaanite, the DNA showed, with a bit of Eastern hunter-gatherer and Eurasian Steppe influence that got added to the mix some 3,000 years ago, the researchers said.

Understanding the Canaanite’s genetic history is important, Haber and Tyler-Smith said, because so few written records of the group’s story remain.

“Genetics has the power to fill these gaps,” the two told Live Science. The Near East is a key place for these sorts of studies, the researchers said, because it was such a central location in human history.

The next steps are to study “more samples, different places and different time periods,” Haber and Tyler-Smith said.

The researchers reported their findings online today (July 27) in The American Journal of Human Genetics.

Original article on Live Science.