Water Bear Dries to a Crisp Then Comes Back to Life
The aquatic animal's ability to spring back to life from extreme conditions holds promise for new medical treatments.
Photo: Face of the water bear (Ramazzottius variornatus). Credit: Tanaka S, Sagara H, Kunieda
Small aquatic animals known as water bears can survive near complete desiccation and other extreme states, and now researchers have identified a unique protein that makes such feats possible.
Since the protein, reported in the journal Nature Communications, protects human cells from damage, it could lead to new medical treatments. At the very least, its discovery helps explain how water bears, also known as tardigrades, are among the world's most durable creatures.
Watch how this water bear dries to a crisp before before being brought back to life with a drop of water:
"The dehydrated tardigrades withstand a wide range of physical extremes that normally disallow survival of most organisms, such as extreme temperatures, high pressure, immersion in organic solvent, exposure to high dose irradiation and even direct exposure to open space," wrote lead author Takuma Hashimoto of The University of Tokyo and colleagues.
"Space" refers to the vacuum of outer space, so even NASA is interested in water bears because they suggest that life could be possible in the extreme conditions of other planets.
To determine why water bears are near indestructible, Hashimoto and his team conducted a genetic analysis on one of the most stress tolerant tardigrade species: Ramazzottius varieornatus. It is the toughest of the tough in the animal kingdom.
The researchers identified a unique water bear protein that suppresses X-ray induced damage by about 40 percent in human cultured cells. It also made human cells more tolerant of radiation. Those findings open up a whole new line of research on the water bears' proteins , which could prove to be very beneficial to humans.
The research also presents the first ever genome sequence for an "extremotolerant" tardigrade. As that descriptor indicates, these animals can again survive almost anything.
It is especially impressive that they can live through being dried to a crisp. Novelty aquarium pets known as Sea Monkeys, which are actually brine shrimp, have a similar ability. When desiccated, these brine shrimp go into a different state of being called cryptobiosis or anhydrobiosis. It's a condition of apparent lifelessness that allows survival, even when the temporary water pools in which the brine shrimp live in the wild dry up.
Microscopic water bears live in almost every place on Earth. They can be found in leaf litter and soil, beaches, dunes, fresh and salt water, and even in the slimy film of water that collects on lichens and mosses.
A water bear walking on moss:
Water bears can also survive under conditions of very high pressure. For example, they have no problem withstanding six times the pressure of the deepest part of the ocean. They can be placed in boiling alcohol and come out just fine. Being frozen in a block of ice poses no problem for water bears. They can alsowithstand levels of X-ray radiation that are 1,000 times the lethal human dose.
At the root of many of these abilities is the water bears' ability to survive oxidative stress. This is a disturbance to the balance between the production of reactive oxygen molecules (free radicals) and antioxidant defenses.
Learning more about how they avoid extreme stress could lead to important medical discoveries. The newfound protein is just a start.
Photographer Imre Potyó captured this image of Danube mayflies engaged in a courtship dance. The photo is the overall winner of the Royal Society competition. "At the beginning, females and males fly above the water surface where they copulate," Potyó said. "After that the females begin their upstream-directed compensatory flight, which ends when they deposit their eggs onto the water surface. This shot captures the fantastic energy and chaos of the mayflies' dance and the mood of the night time too."
The winner of the Ecology and Environmental Science category is this photo of a solitary juvenile clown fish (Amphiprion bicinctus) seeking shelter in a bleached bubble-tip anemone in the Red Sea. The photo was snapped following a global bleaching event that has decimated coral reefs worldwide this year. "The lone fish seems like a timely analogy for a generation that may grow up in a bleak future," said photographer Tane Sinclair-Taylor, "without the colorful and diverse coral reefs that we have today."
The winner of the Micro-Imaging category is this photo of an activated carbon grain, which looks like an alien landscape. Photographer María Carbajo Sánchez magnified the grain 5,000 times with an electron microscope to obtain such a close-up view of the tiny object. The source of the carbon was a nutshell.
An eagle ray swimming over the reef with its prey was the subject of the Evolutionary Biology category winner. "Eagle rays have evolved very long tails, but this is the longest that I have ever seen," said photographer Nick Robertson-Brown.
Shooting from the inside of a large mammal carcass with the help of a long trigger wire, photographer Jonathan Diaz-Marba captured the moment when a griffon vulture searched inside the dead animal's ribcage. The photo is a runner up in the Behavior category. "My fear was that these huge birds could vandalize the expensive photographic equipment, but I had to take the risk," Diaz-Marba said.
The birds nest in colonies on cliffs undisturbed by humans, and they fly over huge open areas searching for food. "I chose an area with many magpies, whose presence gives the vultures a good cue of where to feed," he said.
This image of a trainworm (Myrianida pinnigera) took runner up in the Evolutionary Biology category. "Its front end, the trainworm's engine, is followed by a row of carriages called 'stolons' that increase in size towards the worm's tail end," said Frederik Pleijel, who took the photo. "The carriages are the worm's swimming sexual organs."
"When the trainworm is mature, the last carriage in the train lets go and detaches," he said. "It swims up the water column to reproduce."
Photographer Tegwen Gadais captured "Gentoo penguins seemingly 'decorating' their nest with guano" in this photo, taken on the island of South Georgia in the southern Pacific.
"Once the eggs have been laid, each parent will take turns incubating them, relieving themselves by lifting their tails away from the nest and creating the long streaks seen in the picture," Gadais said.
The photo was a runner up in the Ecology and Environmental Science category.
A runner up in the Micro-Imaging category, this photo shows an African house snake (Boaedon fuliginosus) one day after its mother laid her eggs. Photographer Tyler Square noticed that many of the features at this early developmental stage, such as muscle segments and a chambered heart, are shared with other animals.
Looking more like jellyfish or subjects of an Andy Warhol painting, the objects in this special commendation photo are actually carbon nanotubes grown in a pillar formation. "The metal disks that make up the jellyfish bodies are made by 'sputtering' charged aluminum and iron ions onto a surface to deposit a thin film of the metals," said photographer Clare Collins.
A special commendation went to this human-like photo of Japanese macaques huddling to stay warm during the winter. "When they huddle in these small groups it's called in Japanese saru-dango; saru means 'monkey' and dango is a skewer of Japanese sweet dumpling made from rice flour," photographer Alexandre Bonnefoy said. "These groups are composed only of members of the same family."
"This behavior is not observed everywhere in Japan, but only in (a) few groups," he said. "It's a cultural behavior peculiar to the monkeys in Shodoshima and in Nagano, where this photo was taken, where there is a hot spring which the monkeys bathe in."
A special commendation also went to this photo of colorful butterflies gathering on the head of a caiman. "A number of minerals are a scarce resource throughout Amazonia," said Mark Cowan, who took the photo. The behavior allows insects like butterflies to have access to salt, even if it is on the head of a large predatory reptile.
"This particular phenomenon where butterflies and bees congregate on the heads and around the eyes of caimans and turtles has been documented before," he added, "but what is unique here is the simultaneous number of butterfly species and the way in which each species is associated with its own kind."
The winner of a special commendation, publisher's choice, goes to this photo of a superb fan-throated lizard (Sarada superba) native to the northern Western Ghats of India. "About two decades ago, a large part of this plateau was converted into one of Asia's largest wind farms," photographer Prasenjeet Yadav said. "This has resulted in drastic changes in the ecology of this charismatic lizard species."
The lone lizard appears to be contemplating the seemingly inescapable human-caused changes to its habitat.