Life in the Dark - Deep Sea Ecosystems

Biologists always thought life required the Sun's energy, until they found an ecosystem that thrives in complete darkness.

Dr. Cindy Van Dover manoeuvres her robotic craft closer to the strange, rocky landscape below. It's totally dark, except for lonely circles of light where she points her flood lamps. Back on the mother ship her monitor reveals tall, thin towers of craggy rock billowing black smoke from their peaks. Very strange!

All around the towers stand dozens of red-and-white, tube-like organisms. These bizarre, 3-foot-long, wormish creatures have no mouth, no intestines, and no eyes. Stranger still, they derive their energy from the planet itself, not from the light of the nearby star -- a feat most biologists didn't believe possible until these creatures were found.

She steers toward the worms and uses the robotic arm to reach out and take a sample for later examination.

Is this a science fiction tale? No. Is the intrepid Dr. Van Dover truly exploring another world? Yes!

Van Dover is as real as is the alien world she's discovering. And both are right here are Earth!

Cindy Van Dover, a marine biology professor at the College of William and Mary in Williamsburg, Virginia, is one of some 60 scientists, technicians and sailors who sailed aboard the research vessel Knorr from the Woods Hole Oceanographic Institution between March 27th and May 5th 2001. This 40-day expedition sent a 1-ton robotic submarine named JASON 2,000 metres down to explore the peculiar sunless world of deep-sea hydrothermal vents.

Images courtesy Woods Hole Oceanographic Institution

"I really never thought that one could be an explorer in this day and age," said Van Dover, chief scientist for the expedition and a member of NASA's Astrobiology Institute. "But in the ocean, it's absolutely true," she added. "You're going places that nobody's ever been before!"

A view of a "chimney" vent (top photo) captured by the deep-sea submersible JASON. The superheated black water pouring from the vent provides high-energy chemicals that sustain the tubeworms (bottom photo) and other organisms that thrive in this unlikely habitat.

The hydrothermal vents - which are essentially geysers on the sea floor - support exotic chemical-based ecosystems. Some scientists think the vents are modern-day examples of environments where life began on Earth billions of years ago. And the vents might also hold clues to life on other planets.

The thriving communities of life that surround these hydrothermal vents shocked the scientific world when the first vent was discovered in 1977.

Before 1977, scientists believed that all forms of life ultimately depended on the Sun for energy. For all ecosystems then known to exist, plants or photosynthetic microbes constituted the base of the food chain.

In contrast, these vent ecosystems depend on microbes that tap into the chemical energy in the geyser water that billows out from the sea floor -- energy that originates within the Earth itself.

Because they offer an alternative way for life to meet its fundamental need for energy, these vent ecosystems have piqued the interest of astrobiologists - scientists who study the plausibility of life starting elsewhere in the universe.

"It's the only system we know of on Earth where life can thrive in the complete absence of sunlight," said Bob Vrijenhoek, senior scientist at the Monterey Bay Aquarium Research Institute in Moss Landing, California. Vrijenhoek will conduct DNA analysis on the samples gathered by the expedition.

One chore that astrobiologists have struggled with for years is to define the range of conditions (temperature, salinity, irradiation, chemical composition, etc.) in which "life as we know it" could exist. The discovery of hydrothermal vent ecosystems expanded that range.

Images courtesy Woods Hole Oceanographic Institution The Study Area

"It (the life around the vents) was the first discovery of 'life as we don't know it,'" Vrijenhoek said.

Hydrothermal vents form along mid-ocean ridges, in places where the sea floor moves apart very slowly (6 to 18 cm per year) as magma wells up from below. (This is the engine that drives Earth's tectonic plates apart, moving continents and causing volcanic eruptions and earthquakes.) When cold ocean water seeps through cracks in the sea floor to hot spots below, hydrothermal vents belch a mineral-rich broth of scalding water. Sometimes, in very hot vents, the emerging fluid turns black -- creating a "black smoker" -- because dissolved sulphides of metals (iron, copper, and several heavy metals) instantaneously precipitate out of solution when they mix with the cold surrounding seawater.

Deep-sea bacteria form the base of a varied food chain that includes shrimp, tubeworms, clams, fish, crabs, and octopi. All of these animals must be adapted to endure the extreme environment of the vents -- complete darkness; water temperatures ranging from 2°C (in ambient seawater) to about 400°C (at the vent openings); pressures hundreds of times that at sea level; and high concentrations of sulphides and other noxious chemicals.

The ability of life to tap such geothermal energy raises interesting possibilities for other worlds like Jupiter's moon Europa, which probably harbour liquid water beneath its icy surface. Europa is squeezed and stretched by gravitational forces from Jupiter and the other Galilean satellites. Tidal friction heats the interior of Europa possibly enough to maintain the solar system's biggest ocean. Could similar hydrothermal vents in Europa's dark seas fuel vent ecosystems like those found on Earth? The only way to know is to go there and check.

Images courtesy Woods Hole Oceanographic Institution

A variety of animals live near these hydrothermal vents, including the shrimps, crab, and anemone in this picture taken at the Indian Ocean vent. So far, the hallmark red and white tubeworms have not been spotted at this vent.

Astrobiologists are increasingly convinced that life on Earth itself might have started in the sulphurous cauldron around hydrothermal vents. Vent environments minimise oxygen and radiation, which can damage primitive molecules. Indeed, many of the primordial molecules needed to jump-start life could have formed in the subsurface from the interaction of rock and circulating hot water driven by hydrothermal systems.

If this idea proves true, then the next time Van Dover gazes through the submarine's camera at the vents on the floor of the Indian Ocean, she may be seeing both a portrait of life's genesis in Earth's distant past - and a glimpse of alien life yet to be discovered.

Read more ...

Herbal Remedies Reviewed

Herbal remedies can be a more natural alternative to treating medical problems, but they also have their dangers.

Photo courtesy of Luke Hansen

A herbal solution? Many people are now choosing to treat their medical problems with herbal remedies.

Many people are now choosing to cut out the middleman by treating their medical problems themselves with herbal supplements. The face of herbal medicine, once dominated by patchouli-scented hippies and gauzy New Age types, is changing. Soccer moms are treating their children's colds with chicken soup and echinacea and college students fuel all-night study sessions with energy drinks boasting ginkgo and ginseng. Even in your local convenience store, snacks and drinks touting herbal ingredients are slowly encroaching on traditional junk food territory.

Every year, the Centers for Disease Control and Prevention (CDC) conduct a health survey of American households and a variety of other groups may request supplemental surveys as well. In 2002, the National Center for Complementary and Alternative Medicine, which studies everything from yoga to acupuncture, sponsored a supplemental survey to measure herbal and dietary supplement use.

What the Survey Said

Jae Kennedy of Washington State University used this information to provide the first detailed national portrait of herbal medicine in the U.S., which was published in Clinical Therapeutics in January 2006. He found that echinacea, ginseng, ginkgo and garlic were, in that order, the most common herbs regularly taken by Americans. Nearly one fifth of Americans (38.2 million people), regularly took at least one type of herbal or dietary supplement. This number had doubled in only three short years since the previous survey in 1999 and is likely to be even higher now.

Kennedy found that regular herbal and dietary supplement use was higher among women, middle-aged adults, and college graduates. People with multi-racial, Asian, or Native American backgrounds also reported a higher usage. Using herbs and dietary supplements seems to be part of a concerted effort to improve health: generally, herbal supplement users exercise regularly, no longer smoke cigarettes, and report being in good or excellent health.

Kennedy's findings also show that most people use herbal medicine to complement conventional medicine, not to replace it. "For some conditions like depression and chronic pain, herbs might be a less toxic, less extreme kind of solution," says Kennedy. "These kinds of conditions are tough to treat effectively with conventional drug treatment."

Read more ...

Life at the Extremes

Some living species are able to thrive in inhospitable environments. How do they do it?

Life has flourished here on Earth. Typically, living things are found in warm, wet, sunlit zones, at pressures similar to those at sea level and in conditions that are neither acidic nor alkaline. But living cells have also been found in areas that seem inhospitable to life: in hot springs, lying dormant buried in ice, in acid-filled caves and in the depths of the ocean. By exploiting new environments, these pioneering organisms gain a competitive advantage that allows them to proliferate. How are they able to tolerate these conditions?

Credit:www.carleton.ca/~kbstor ey

Wood frogs survive cold winters by freezing solid and thawing out in the spring. They have developed 'antifreeze proteins' that control the shape of ice crystals that form, and minimise the physical damage caused by its expansion.

Normal versus extreme

Life is inextricably linked to water and is usually found within the range of temperature and pressure where liquids can exist. Organisms that live on land tend to favour a temperature range of 10 degrees C to 48 degrees C, while life in the ocean exists at around 2 degrees C year round. At higher temperatures, vital long chain carbon molecules acquire too much energy from their surroundings and lose their important 3D shapes. At lower temperatures, chemical reactions slow down, making it difficult to sustain metabolism. At subzero temperatures, water inside living organisms can form ice crystals which damage the delicate internal architecture of cells.

Low pressure environments are rare, even at the top of the tallest mountain ranges. High pressure is a much more common stress factor, particularly at the bottom of oceans where the weight of the water generates a crushing force up to 1,100 times the pressure at the surface. There is also a lot of pressure inside rocks and sediments beneath the surface of the Earth where some bacterial species have been found.

In addition to these physical constraints, chemical stress factors like salt concentration and pH, a measure of how acid or alkali an environment is, also affect what can survive in an environment. All living things separate themselves from the outside world with a cell membrane. This allows them to control the concentrations of important or dangerous chemicals within their cells. In very salty conditions, cells struggle to retain their water as it floods out to dilute the salt outside the cell. Many of the problems associated with salty environments are due to lack of water.

The pH of an environment also has many consequences for cells. Since most biological processes occur in the neutral range of the pH scale, biological molecules lose their function in both acid and alkali environments (low and high pH respectively).

Read more ...

Tall Tales: Giant Squid

Are the oceans hiding monsters of epic proportions? And will they survive long enough for us to track them down?

Hemmed in on all sides by two metre-long, tentacled sea demons, Scott Cassell must have thought he’d breathed his last...

30 minutes later he emerged from what would have been his watery grave, just off the coast of Mexico, saved only by his armour-plated diving suit.

A veteran deep sea film maker, Cassell was on a mission to get an image on camera of the Mexican Rojo Diablo, the 'red demon' or Humboldt squid. At up to 50 kilograms, these vicious sea beasts can throw enough weight to do some serious damage to an unprotected diver. Cassell was anything but unscathed after his own terrifying encounter. “I later discovered bruises on me the size of oranges, as well as several scratches in my anti-squid armour suit,” he says.

Undeterred, Cassell has returned to squid-infested waters on numerous occasions since his lucky escape. Most recently, in November 2007, the History Channel aired his new documentary in which he and his team manage to saddle a Humboldt squid with an underwater camera. The images they return hint at something much, much larger lurking in the deep. A squid, perhaps, of such epic proportions that it would dwarf anything previously hauled in by squid hunters.

What haunts the deepest, darkest recesses of the ocean has alternatively fascinated and terrified our sea-faring ancestors for centuries. Writing in 1755, the bishop of Bergen in Norway, painted a picture of a monster a mile long, which he called a ‘Kraken’. And in 1770, the Royal Society heard Charles Douglas’ account of “an animal of 25 fathoms long”, related to him by a Norwegian sea captain. Among the fables and fabrications, however, there may just lie an inkling of the truth.

The one that got away

Cassell’s giant, which he claims may have measured anything up to 30 metres in length – as big as a blue whale – was most likely a cousin to his old enemy, the Humboldt. So-called giant and colossal squid belong to the same family of backboneless sea creatures, falling under the general umbrella of cephalopods. It is only relatively recently, however, that scientists have begun to understand anything about the lives of these much larger cephalopods, which are notoriously elusive. “With giant squid, we catch so few - it’s not like working on something like an earthworm where you can dig up a million and compare them all,” says Louise Allcock, a cephalopod expert at the University of Aberdeen. “We’re getting a couple a year if we’re lucky.”

It may not be so difficult to appreciate why such enormous entities should be so difficult to run into. Firstly, they dwell far below the water’s surface, sometimes as deep as a kilometre. And secondly, they don’t easily fall for our tricks. “They are very smart, very fast, they hunt, they live in mid-water and they rarely come to you,” says Alan Jamieson, a researcher developing deep sea observation systems at the University of Aberdeen.

Jamieson spent part of last year with the Japanese Marine Science and Technology Center (JAMSTEC) in Tokyo, where researchers shot the first ever footage of a live giant squid in its home environment in 2005. But they had to try every trick in the book to get it, eventually resorting to an elaborate system of buoys, cables and hooks, dangling a camera and some shrimp bait. Squid like their prey alive and tend not to be drawn by the static observation vehicles often deployed by scientists. “Short of catching a live fish and strapping some poor guy in front of a camera like a sacrificial lamb, they are only seen as chance encounters,” says Jamieson.

These encounters have been so rare that even basic information about larger species of squid is missing from the marine biologist’s manual. “There is much we have to learn about these animals,” says Steve O’Shea, Director of Auckland University of Technology’s Earth and Oceanic Sciences Research Institute in New Zealand. “Life cycle, growth rate, distribution and abundance all have yet to be determined.” According to O’Shea thereis enough work to be done to occupy squid specialists for generations.

Read more ...

Fruit Flies Unravel Brain Mysteries

Scientists are investigating the genetic system of the Drosophila fruit fly to discover how humans perceive the world and make choices

For almost a century, scientists have used the fruit fly (scientifically known as Drosophila melanogaster) as a model organism for investigating various biological systems. Today it remains the most studied organism in biological research.

The fruit fly's robust genetic system makes it an invaluable tool for scientists studying inheritance. Drosophila is being used as a genetic model for several human diseases, including neurodegenerative disorders such as Alzheimer's, Parkinson's and Huntington's disease. Researchers are also using the fly to study mechanisms underlying ageing, immunity, diabetes, and cancer.

Other scientists are using the fruit fly to test some basic ideas about how we - and other animals - see the world around us. Visual information is clearly important for many organisms. An animal's visual system is what allows it to see, by interpreting the information from light to build up a representation of the world surrounding its body.

Whilst researchers know the functional architecture of the brain and eye of the Drosophila in great detail, they don't know much about the route that the visual information takes, and how it's processed in the nervous system. By using electrophysiological and imaging experiments, scientists can learn a lot about how individual neurons - or groups of neurons - process visual signals. But it's only through experiments studying the behaviour of flies that hypotheses about visual processes can be proved or abandoned.

Why use Drosophila?

Drosophila (pictured) is a small fly about 3mm long that lives for only around two weeks. Researchers can speed up or slow down their life cycle, by varying the temperature they are kept in. Fruit flies are also cheap, and easy to keep in large numbers. They are easy to handle, are well-understood and their entire genome has recently been sequenced (completed in 2000).

Scientists can also study mutant flies, with defects in any of several thousand genes. A mutant fly is one that has a change in the sequence of the nucleotides in the DNA of a particular gene, which could mean that it can't produce a particular enzyme or protein properly. By using Drosophila mutants, scientists can look at the role of a specific part of a cascade or pathway in the fly.

Similarly, scientists can increase the number of enzymes or proteins in the fly to investigate its effect. They can compare a mutant fly with a missing enzyme to a normal fly, and thus shed light on the function of that missing enzyme.

The Drosophila has a big advantage over human genetic material, as it has only four pairs of chromosomes, compared to humans who have 23 pairs - so there is less genetic information for researchers to deal with. Scientists can effectively breed the flies to contain the genes or mutant genes they require, to study anything from very precise mechanisms to general behavioral responses.

The Drosophila genome shares many similarities to the human genome. Of 289 genes known to cause disease in humans - including cancer, neurodegenerative and cardiovascular diseases - researchers discovered about 175 in Drosophila.

Read more ...

Superbugs that Dine on Antibiotics

There's something lurking about your garden, weaving in and out of your vegetables and making itself at home. You can't see it, but it's there. Deep down under the soil lies a ravenous 'ultrabug', a bacterium able to survive only on antibiotics - the very drugs that are supposed to kill it.

Recently, while hunting for soil bacteria that can turn plant waste to biofuels, a team of microbiologists led by George Church of Harvard University, Boston, Massachusetts, found a strain of Pseudomonas bacteria (right) that could survive on antibiotics. The researchers collected soil bacteria from many places such as farms, forests and parks around the northeast United States and Minnesota.

They used antibiotics as an experimental control; and discovered that these bacteria were able to survive on many different antibiotics, both natural and manmade, including frequently used antibiotics for childhood illnesses. In all cases, not only did the bacteria just survive but they flourished while eating the antibiotics.

How could this happen? Should we be concerned? And is this the next superbug?

Beneficial Germs

Most people think of bacteria as "germs," invisible creatures that can invade our bodies and make us sick.

However, not all bacteria are harmful; in fact, many bacteria are quite useful. There are over a thousand types of bacteria in the normal human intestines that make vitamins such as folic acid and vitamin K, and can also help digest milk proteins such as lactose. Other bacteria help clean up oil spills by devouring the oil as food. Some bacteria decompose compost, garbage and sewage and help make methane which is used as fuel. It's difficult to imagine our life without some of these bacteria.

Interestingly, bacteria can also be found everywhere from soil, water, acidic hot springs and radioactive waste (left), to locations deep in the Earth's crust, as well as in plants and animals. These bacteria are essential for the stable ecosystem in which we live.

Bacteria also play a major role in scientific research and drug development. Bacteria in the lab can be genetically engineered to make proteins that are useful for humans, such as insulin and human growth hormone. Certain human genes that are responsible for making proteins such as insulin are inserted into bacteria like E. coli, to produce synthetic 'human' insulin in large quantities.

Read more ...

Tardigrades: The World's Toughest Critters

The humble water bear has been the subject of some pretty nasty experiments lately. Scientists have boiled them in pure alcohol, exposed them to pressures six times greater then on the deepest ocean floor, and even frozen them to near absolute zero.

"Why?" I hear you cry. Well, scientists are testing the limits of the toughest creatures on Earth, with an incredible ability to survive the harshest conditions we can dream up. These little guys are more impressive endurance artists than David Blaine, and better survivors then even the mighty Ray Mears.

In September 2008 a crew of water bears were subjected to the most imaginative test yet; they were launched into orbit and exposed to the intense radiation and frigid vacuum of space before returning to Earth. Many were found to have survived the trip intact, and produced healthy offspring as though they had just been on vacation .

Introducing the Water Bear...

Water bears (also known as tardigrades) are arguably the cutest microscopic invertebrates ever discovered. They are short and plump with eight podgy legs and a smooth "gummy bear" complexion. They walk with big, lumbering strides and each foot has up to eight claws. Their mouse-like snout contains a tube which they use as a drinking straw to pierce their food and suck nutrients like out of a juice carton.

They are usually less then 1.5 mm long, so can only just be seen with the naked eye, but photos taken using microscopes reveal them to be a vivid red colour.

Although not many people have heard of them, these fantastic beasts actually live among us; in fact there is probably a water bear within 10 meters of you right now! These tough little creatures have been found all over the globe, from 6000m high in the Himalayas to depths of 4000m at the bottom of our oceans. Scientists have studied them on hot sand dunes at the equator, and 5m below the ice in Antarctica. Although they are known to inhabit some of the most extreme environments on Earth, they are happiest living on damp moss. They are aquatic animals and thrive in lakes, ponds, and moist patches in stone walls and roofs.

Read more ...