Whale Bone eating worms – Surprise Scientists

A member of a species likely new to science, the Osedax yellow-collared worm feasts on whale bones in 2008. Named for the thin yellow ring that runs around the base of the worm’s feathery structures–thought to be used for respiration–the species lives below 3,280 feet (1,000 meters).

The first known Osedax worms, which tend to feed on whale remains, were first scientifically described in 2004. A short five years later, new types of the bone-eating worms are turning up as fast as scientists can study them. (See “New Worms Eat (and Eat and Eat) Only on Dead Whales.”)

So far, scientists have confirmed five Osedax species, which live between 82 feet to 9,842 feet (25 to 3,000 meters) deep in the Pacific and Atlantic Oceans. And in November researchers from the Monterey Bay Aquarium Research Institute revealed evidence of 12 more potentially new species, including the yellow-collar, all found in the undersea canyon off Monterey, California.

–Matt Kaplan

—Photograph courtesy Greg Rouse, MBARI

http://news.nationalgeographic.com/news/2009/11/photogalleries/091202-ocean-worms-eat-bones/index.html

Top Ten Discoveries of 2009: Nat Geo News’s Most Viewed

National Geographic News’s most popular coverage of 2009 scientific finds is swarming with megamouth sharks, giant snakes, a transparent-headed fish, and rare species rescued from obscurity—then eaten.

10. Ultra-Rare Megamouth Shark Found, Eaten In March, the 41st megamouth shark ever found went from swimming in Philippine waters to simmering in coconut milk.

9. Ancient Gem-Studded Teeth Show Skill of Early Dentists The glittering “grills” of some hip-hop stars aren’t exactly unprecedented. Sophisticated dentistry allowed Native Americans to add bling to their teeth as far back as 2,500 years ago, a May study said.

8. Alien Giant Snakes Threaten to Invade Up to 1/3 of U.S. Nine giant snakes could be on the verge of causing ecological catastrophe if they establish themselves in the U.S. wild&—at least two have already set up shop in Florida&—according to an October report. • See pictures

7. Biggest Snake Discovered; Was Longer Than a Bus The 60-million-year-old reptile was also heavier than a car, scientists said in February, adding that the fossil could shed light on climate change. • See pictures

6. Gold Rush-Era “Ghost Ship” Wreck Found With boots thrown hastily on deck and cooking utensils scattered, the last moments of the crew aboard the gold rush-era paddleboat A.J. Goddard are preserved in the ship’s recently found wreck, archaeologists announced in November.

5. Oldest Skeleton of Human Ancestor Found There was never a chimp-like missing link between humans and today’s apes, according to an October fossil-skeleton study that could rewrite human evolutionary history. Said one scientist, “It changes everything.” • See pictures

4. “Extinct” Bird Seen, Eaten Long believed to be extinct, a rare quail from the Philippines was photographed for the first time ever—then sold at a poultry market, experts said in February.

3. New Cloud Type Discovered? Nicknamed “Jacques Cousteau” clouds, these “turbulent” seas in the sky could be examples of the first official new cloud type since 1951, experts said in June.

2. Fish With Transparent Head Seen Alive for First Time Perhaps the most bizarre nature discovery of the year—though Stephen Colbert put it a bit less delicately—a Pacific barreleye fish shows off its transparent head and barrel-like eyes in pictures released on February of the first specimen ever found alive. • Watch video

1. “Missing Link” Found: Fossil Connects Humans, Lemurs? The 47-million-year-old, exceptionally preserved primate fossil “Ida,” unveiled on May 20, was hailed by some as a major discovery in human evolution. The publicity frenzy made National Geographic News’s brief coverage our most viewed page of the year—and inspired a backlash as some experts, including one here at Nat Geo HQ, suggested Ida was more media event than milestone.

http://news.nationalgeographic.com/news/2009/12/091202-top-ten-discoveries-2009-year-science-news.html

Malaysian Rainforest Tribes Establish ‘Peace Park’ to Push Back Loggers

photo: Bruno Manser Fonds

by Matthew McDermott

Here’s one solution to holding back loggers: Bruno Manser Fonds reports seventeen Penan communities in Sarawak, Borneo, Malaysia have proclaimed a new tropical forest reserve on their lands. The newly inaugurated Penan Peace Park will preserve their last remaining undisturbed forests from development, allowing tourism and preserving their culture.

Our Heritage Must Be Preserved
A former regional chief in the region, James Lalo Kesoh described the necessity of establishing the park:

As nomadic hunter-gatherers, we Penan people have been roaming the rainforests of the Upper Baram region for centuries. Even though we have settled down and started life as farmers sicne the late 1950s, we still depend on the forests for our food supply, for raw materials such as rattan for handicrafts, for medicinal plants and for other jungle products. Our entire cultural heritage is in the forest and needs to be preserved for future generations.

The Penan Peace Park consists of about 1630 square kilometers around the Gunung Murud Kecil mountain range, near the border of Indonesia.

The Penan people in the region have opposed logging in their rainforest for the past three decades, repeatedly blocking roads and taking direct action against encroachments.

Hat tip to Mongabay on this one…

http://www.treehugger.com/files/2009/12/malaysian-rainforest-tribes-establish-peace-park-push-back-loggers.php

Strange Triangular Snowflakes Explained

By Laura Sanders

Flurries of questions about mysterious triangle-shaped snowflakes may soon subside, thanks to new research on snowflake formation. Most snowflakes are hexagons because of the arrangement of hydrogen bonds in the water molecule. But the new study, appearing online at arxiv.org (http://arxiv.org/abs/0911.4267) and in an upcoming issue of The Microscope, suggests that after hexagonal flakes, oddball triangular flakes are the most prevalent.

Study coauthors Kenneth Libbrecht and Hannah Arnold of Caltech in Pasadena propose an aeronautical reason for the triangular geometry. The results help solve the very old puzzle of how the unexpected flakes form, Libbrecht says.

Snowflake enthusiasts — such as Libbrecht, who photographs snowflakes — have spotted triangular snowflakes in the wild. The snowflake scientific literature, which goes back almost two centuries, is thick with such sightings, Libbrecht adds, but no one has explained why. “People have noticed them for hundreds of years.”

To address the mystery, the researchers created snowflakes in the laboratory and recorded the shapes. In conditions that simulate natural snowfall, the vast majority of flakes were the standard hexagons, but more of them were triangular than a statistical model had predicted, the team found. Some of these flakes still have six sides but an overall triangular shape, created by three short edges and three long ones. The abundance of triangle-shaped flakes suggests that they may be more common in nature than chance alone would allow.

Tiny impurities, such as dust particles, can cause one edge of the falling snowflake to tilt up as it falls, Libbrecht says. The snowflake sides that are pointed down grow faster as the wind blows by, leading to a stable triangular pattern. Once a triangle shape gets started, the snowflake remains triangular despite any later bumps as it falls, the researchers propose.

Image: Kenneth Libbrecht

http://www.wired.com/wiredscience/2009/12/triangular-snowflakes/

How Did Flowering Plants Evolve to Dominate Earth?

Colorful tulips and other spring flowers in the Keukenhof Gardens, the Netherlands. How did flowering plants come to dominate plant life on earth? (Credit: iStockphoto/Monika Lewandowska)

To Charles Darwin it was an ‘abominable mystery’ and it is a question which has continued to vex evolutionists to this day: when did flowering plants evolve and how did they come to dominate plant life on earth? A new study in Ecology Letters reveals the evolutionary trigger which led to early flowering plants gaining a major competitive advantage over rival species, leading to their subsequent boom and abundance.

The study, by Dr Tim Brodribb and Dr Taylor Field of the University of Tasmania and University of Tennessee, used plant physiology to reveal how flowering plants, including crops, were able to dominate land by evolving more efficient hydraulics, or ‘leaf plumbing’, to increase rates of photosynthesis.

“Flowering plants are the most abundant and ecologically successful group of plants on earth,” said Brodribb. “One reason for this dominance is the relatively high photosynthetic capacity of their leaves, but when and how this increased photosynthetic capacity evolved has been a mystery.”

Using measurements of leaf vein density and a linked hydraulic-photosynthesis model, Brodribb and Field reconstructed the evolution of leaf hydraulic capacity in seed plants. Their results revealed that an evolutionary transformation in the plumbing of angiosperm leaves pushed photosynthetic capacity to new heights.

The reason for the success of this evolutionary step is that under relatively low atmospheric C0₂ conditions, like those existing at present, water transport efficiency and photosynthetic performance are tightly linked. Therefore adaptations that increase water transport will enhance maximum photosynthesis, exerting substantial evolutionary leverage over competing species.

The evolution of dense leaf venation in flowering plants, around 140-100 million years ago, was an event with profound significance for the continued evolution of flowering plants. This step provided a ‘cretaceous productivity stimulus package’ which reverberated across the biosphere and led to these plants playing the fundamental role in the biological and atmospheric functions of the earth.

“Without this hydraulic system we predict leaf photosynthesis would be two-fold lower then present,” concludes Brodribb. “So it is significant to note that without this evolutionary step land plants would not have the physical capacity to drive the high productivity that underpins modern terrestrial biology and human civilisation.”

Story Source:

Adapted from materials provided by Wiley-Blackwell, via EurekAlert!, a service of AAAS.

http://www.sciencedaily.com/releases/2009/12/091201100221.htm

Shark Fins Traced to Their Geographic Origin for First Time Using DNA Tools

This is a scalloped hammerhead (Sphyrna lewini) at Cocos Island, Costa Rica. (Credit: Terry Goss 2008/Marine Photobank)

Millions of shark fins are sold at market each year to satisfy the demand for shark fin soup, a Chinese delicacy, but it has been impossible to pinpoint which sharks from which regions are most threatened by this trade. Now, groundbreaking new DNA research has, for the first time, traced scalloped hammerhead shark fins from the burgeoning Hong Kong market all the way back to the sharks’ geographic origin. In some cases the fins were found to come from endangered populations thousands of miles away.

Published online December 1 in the journal Endangered Species Research, the findings highlight the need to better protect these sharks from international trade, a move which will be considered by the Convention on International Trade in Endangered Species (CITES) at its March 2010 meeting in Qatar. The work was led by the Guy Harvey Research Institute and the Save Our Seas Shark Center at Nova Southeastern University and the Institute for Ocean Conservation Science at Stony Brook University.

The U.S. has proposed that CITES list the scalloped hammerhead and five other shark species under the organization’s Appendix II, which would require permits for, and monitoring of, all trade in these species across international boundaries. Knowing the species and geographic origin of fins being traded would allow management and enforcement efforts to be allocated more effectively.

“Although we’ve known that a few million hammerhead shark fins are sold in global markets, we now have the DNA forensic tools to identify which specific hammerhead species the fins originate from, and in the case of scalloped hammerheads, also what parts of the world these fins are coming from,” said Dr. Mahmood Shivji, senior author on the paper and Director of the Guy Harvey Research Institute (GHRI) and Save Our Seas Shark Center, both at Nova Southeastern University (NSU) in Florida. “This trade has operated for years and years under the cover of darkness,” added lead author, Dr. Demian Chapman, now with the Institute for Ocean Conservation Science at Stony Brook University (SBU) in New York. “Our work shows that the scalloped hammerhead fin trade is sourced from all over the globe and so must be globally tracked and managed.”

The new research paper is published in a special theme issue of Endangered Species Research entitled, “Forensic Methods in Conservation Research.” Using CSI-like methods known as “genetic stock identification” or GSI, Drs. Chapman and Shivji along with Danillo Pinhal of the GHRI and Universidade Estadual Paulista, Brazil, analyzed fingernail-sized DNA samples from 62 scalloped hammerhead shark fins that had been obtained in the Hong Kong fin market. By examining each fin’s mitochondrial DNA sequence — a section of the genetic code passed down by the mother and traceable to a sharks’ regional birthplace — the researchers were able to exactly match 57 of the 62 fins to an Atlantic or Indo-Pacific ocean origin.

The team also analyzed mitochondrial sequences taken from 177 live scalloped hammerheads in the Western Atlantic and determined that the species is further divided into three distinct stocks in this region: northern (U.S. Atlantic and Gulf of Mexico), central (Belize and Panama), and southern (Brazil). The scientists traced 21 percent of the Hong Kong fins back to these Western Atlantic stocks. Scalloped hammerheads in the region have been categorized as endangered by the IUCN (International Union for the Conservation of Nature) since 2006. This coastal species appears to have collapsed in the western North Atlantic and Gulf of Mexico.

“The premium prices commanded by fins have fueled a global shark hunt of epic proportion,” said Dr. Ellen Pikitch, Executive Director of the Institute for Ocean Conservation Science at SBU, which funded a portion of the research. “Earlier work found that up to 73 million sharks are killed annually to supply the fin markets, and approximately 1-3 million are hammerheads,” said Dr. Pikitch, who is also a Professor of Marine Science at Stony Brook University. “Inadequate protection, combined with inexorable pursuit, has placed many shark species at grave risk.” Just 1 kg (2.2 lbs) of scalloped hammerhead fin can sell for about $US120 at Hong Kong markets due to the large size and high “fin needle” content of this species’ fins. Needles are the sought-after portion of the fins, used as thickener in the soup.

“The fact that scalloped hammerhead shark DNA shows strong population DNA signatures means that we can trace the geographic origin of most of their fins sold at markets,” Dr. Shivji said. “From a broader perspective, this type of DNA forensic testing of fins will be an incredibly useful tool to prioritize areas for conservation and ensure sharks aren’t wiped out in particular regions by excessive fishing.”

This study builds upon a DNA test developed in 2005 at the Guy Harvey Research Institute by Dr. Shivji and Debra Abercrombie, a research scientist now with the Institute for Ocean Conservation Science at SBU. The test enabled scientists to rapidly and definitively distinguish between three similar hammerhead species: great, scalloped, and smooth, from fin or meat tissues alone. The new GSI technique takes that DNA test to the next level. GSI has been used to trace some fish, sea turtle and marine mammal catches back to their geographic origin. This study marks its first use with sharks. Dr. Chapman is now working on DNA tools to identify a shark’s geographic origins even more precisely, while both he and Dr. Shivji are working on developing GSI for more shark species, including other large hammerheads.

“The international shark fin trade must not continue to operate in secrecy,” Dr. Chapman said. “We must use all tools available — from CITES permitting to DNA tests — to shed light on this trade and make sure that it does not drive these sharks to extinction.” Drs. Pikitch and Chapman plan to attend the CITES meeting in Qatar in March to urge that these sharks be listed under Appendix II to receive better protection from trade.

This research was funded by the Institute for Ocean Conservation Science at SBU, the Guy Harvey Research Institute at NSU and the Save Our Seas Foundation.

Story Source:

Adapted from materials provided by Stony Brook University, via EurekAlert!, a service of AAAS.

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Journal Reference:

1. Chapman et al. Tracking the fin trade: genetic stock identification in western Atlantic scalloped hammerhead sharks Sphyrna lewini. Endangered Species Research, 2009 DOI: 10.3354/esr00241

http://www.sciencedaily.com/releases/2009/12/091201084158.htm

Whale Song – ‘Pop Culture’ of the Planet’s Largest Species

Scientists are starting to consider the notion that whales might have a pretty cool culture. It looks as though Herman Melville picked the right hero for his epic novel..

“Whales are pretty hard to study, but evidence is coming up from quite a number of species that in a whole range of ways, they’re learning things from each other and they’re passing it on to other whales, and that’s culture,” says Hal Whitehead, biology professor at Dalhousie University in Nova Scotia, Canada.  Whitehead says whales don’t have opposable thumbs, so they can’t craft material objects to pass on through the generations: “Whale cultures are in their minds and not in the things that they make.”

“Whale culture has, like human culture, a range of types and styles,” says Whitehead. “At one end, there are the fast moving what might be called ‘pop’ cultures, such as when male Humpback whales sing songs to attract females or ward off other males. “These songs evolve, so that at the beginning of the breeding season they’re all singing one song and then it’s changed a bit by the end,” says Whitehead. “And after a couple of years they’re singing a totally different song.”

But other whale languages are more constant and enduring. The dialects of killer whales, which travel in large extended-family groups called pods, “seem to change much more slowly and to be linked to particular social structures,” says Whitehead. “A particular pod will have its own dialect, and that dialect will be similar to pods which are the members of the same clan, and clans will have dialects which are different from one another—just as humans from different parts of the same country may sound a bit different, but humans from different countries may be totally unintelligible to each other,” says Whitehead. And these dialects will be stable. “In sperm whales which we study, we can record a group of sperm whales now, we can record them ten years from now, and we won’t notice any difference in the sounds they’re making.”

Whitehead notes that different pods of whales can have distinctly different sets of behaviors and languages even though they share territory. “We find this situation where we have multi-cultural societies,” he says. “In one place, there are animals who make their living in very different ways.”

Sperm whales off the Galapagos islands have two distinct ways of speaking. These whales speak in a series of clicks, but some of them often add a pause and a final “click.” Where this is important, says Whitehead, is that depending upon the weather, one group may survive better than the other. He notes that the whales with the last click accent seem to thrive in El Nino years, when the water is much warmer, while the group without the accent prefers the colder waters of normal years.

Sperm whale clans appear to have distinct cultures and dialects. Some of these clans are itinerant, traveling great distances in short periods of time; others appear to be sedentary, remaining in one place for days. Whitehead transcribes the variation in vocalizations between clans. Group A: “Click-Click-Click-Click-Click,” Group G “Click-Click-Click-Click-pause-Click,” Group T “Click-Click-pause-Click-Click.” These codas are preserved across the ocean and over time, each repertoire “a group property.” Cultural inheritance in sperm whales is not only observed in their clicks and pauses but also in the variation in foraging patterns, synchronized dives, even defecation rates. To Whitehead, clan identity is similar to nationality in humans. Membership in a dominant clan can increase the chances of survival and of reproduction.

Humpback whales also show evidence of cultural transmission. In any year, whales sing identical songs in Hawaii and Mexico, breeding areas that are 4,500 kilometers apart. How do they manage this? Perhaps they hear the songs across long distances or learn them during the summer months, when different groups gather in the north to feed. More remarkable than the geographic consistency is the change in calls over time. Slight variations in the songs occur each year. But, as with evolution, these changes can make huge leaps in a short time. The Australian biologist Mike Noad and colleagues found evidence of a ‘cultural revolution’ in the Southern Hemisphere. In 1996 two male humpbacks from the Indian Ocean arrived in the Pacific with a new song. Within two years, all the Pacific males had changed their tune, picking up the migrants’ songs.

Why did the song change? It’s not clear, but what is clear is that whales have a sophisticated culture. And who knows, it may be a culture that provides them with the tools to outlive that of homo sapiens. The fact that they took the opposite revolutionary route of human’s by going from land to sea 50 million years ago.was a stroke of genius. After all, this the water planet.

As evolutionary biologist Neil Shubin points out, “In one sense, evolution didn’t invent anything new with whales. It was just tinkering with land mammals. It’s using the old to make the new.”

Posted by Casey Kazan.

This research was funded by the Natural Sciences and Engineering Research Council of Canada.

http://www.oceania.org.au/soundnet/features/culture.html

http://www.eoearth.org/article/Whale_communication_and_culture

http://www.dailygalaxy.com/my_weblog/2009/12/scientists-are-starting-to-consider-the-notion-that-whales-might-have-a-pretty-cool-culture-maybe-the-great-white-whale-was.html

Schooling fish inspire efficient wind farms

SCOTT TUASON / AFP – Getty Images
By basing wind turbine arrangements on schooling fish, engineers hope to improve efficiency.

By Jessica Marshall

The patterns that schooling fish form to save energy while swimming have inspired a new wind farm design that researchers say will increase the amount of power produced per acre by at least tenfold.

“For the fish, they are trying to minimize the energy that they consume to swim from Point A to Point B,” said John Dabiri of the California Institute of Technology in Pasadena, who led the study. “In our case, we’re looking at the opposite problem: How to we maximize the amount of energy that we collect?”

Because both of these problems involve optimizing energy, it turns out that the model that’s useful for one is also useful for the other problem.”

Both designs rely on individuals capturing energy from their neighbors to operate more efficiently.

“If there was just one fish swimming, it kicks off energy into the water, and it just gets wasted,” Dabiri said, “but if there’s another fish behind, it can actually use that kinetic energy and help it propel itself forward.”

The wind turbines can do the same thing. Dabiri’s wind farm design uses wind turbines that are oriented to rotate around the support pole like a carousel, instead of twirling like a pinwheel the way typical wind turbines do.

Like the fish, these spinning turbines generate a swirling wake. The energy in this flow can be gathered by neighboring turbines if they are placed close enough together and in the right position. By capturing this wake, two turbines close together can generate more power than each acting alone.

This contrasts with common, pinwheel-style wind turbines where the wake from one interferes with its neighbors, reducing the neighbors’ efficiency. The vortexes occur in the wrong orientation for the neighboring turbines to capture them.

For this reason, such turbines must be spaced at least three diameters to either side and 10 diameters up — or downwind of another, which requires a lot of land.

Although individual carousel-style turbines are less efficient than their pinwheel-style counterparts, the close spacing that enhances their performance means that the amount of power output per acre is much greater for the carousel-style turbines.

Dabiri and graduate student Robert Whittlesey calculated that their best design would generate 100 times more power per acre than a conventional wind farm.

The model required some simplifications, however, so it remains to be seen whether tests of an actual wind farm produce such large gains. That will be the team’s next step. “Even if we’re off by a factor of 10, that’s still a game changer for the technology,” Dabiri noted.

In the end, schooling fish may not have the perfect arrangement. The pair found that the best arrangement of wind turbines did not match the spacing used by schooling fish.

“If we just mimic the fish wake, we can do pretty well,” Dabiri said. “But, as engineers, maybe we’re smarter than fish. It turns out that for this application there is even better performance to be had.”

This may be because fish have other needs to balance in their schooling behavior besides maximizing swimming efficiency. They seek food, avoid predators and reproduce, for example.

“I think that this is a very interesting possibility,” said Alexander Smits of Princeton University. But a field test will show the idea’s real potential, he noted: “You have to go try these things. You can do a calculation like that and it might not work out. But it seemed like there was a very large reduction in the land usage, and even if you got one half of that, that would be pretty good.”

© 2009 Discovery Channel

http://www.msnbc.msn.com/id/34209634/ns/technology_and_science-future_of_energy/

Biological Basis of ‘Bacterial Immune System’ Discovered

Bacteria and archaea (first discovered in extreme environments such as deep-sea volcanic vents, such as the one shown above) manage to survive thanks in part to a built-in defense system that helps protect them from many viruses and other invaders. (Credit: OAR/National Undersea Research Program (NURP); NOAA)

Bacteria don’t have easy lives. In addition to mammalian immune systems that besiege the bugs, they have natural enemies called bacteriophages, viruses that kill half the bacteria on Earth every two days.

Still, bacteria and another class of microorganisms called archaea (first discovered in extreme environments such as deep-sea volcanic vents) manage just fine, thank you, in part because they have a built-in defense system that helps protect them from many viruses and other invaders.

A team of scientists led by researchers at the University of Georgia has now discovered how this bacterial defense system works, and it could lead to new classes of targeted antibiotics, new tools to study gene function in microorganisms and more stable bacterial cultures used by food and biotechnology industries to make products such as yogurt and cheese.

The research was published November 26 in the journal Cell.

“Understanding how bacteria defend themselves gives us important information that can be used to weaken bacteria that are harmful and strengthen bacteria that are helpful,” said Michael Terns, a professor of biochemistry and molecular biology in UGA’s Franklin College of Arts and Sciences. “We also hope to exploit this knowledge to develop new tools to speed research on microorganisms.”

Other authors on the Cell paper include Rebecca Terns, a senior research scientist in biochemistry and molecular biology at UGA; Caryn Hale, a graduate student in the Terns lab at UGA; Lance Wells, an assistant professor of biochemistry and molecular biology and Georgia Cancer Coalition Scholar at UGA and his graduate student Peng Zhao; and research associate Sara Olson, assistant professor Michael Duff and associate professor Brenton Graveley of the University of Connecticut Health Center.

The system, whose mechanism of action was uncovered in the Terns lab (Michael and Rebecca Terns are a husband-wife team), involves a “dynamic duo” made up of a bacterial RNA that recognizes and physically attaches itself to a viral target molecule, and partner proteins that cut up the target, thereby “silencing” the would-be cell killer.

The invader surveillance component of the dynamic duo (an RNA with a viral recognition sequence) comes from sites in the genomes of bacteria and archaea, known technically as “clustered regularly interspaced short palindromic repeats” or more familiarly called CRISPRs. (A palindrome is a word or sentence that reads the same forward and backward.) CRISPR RNAs don’t work alone in fighting invaders, though.

Their partners in invader defense are Cas proteins that arise from a suite of genes called “CRISPR-associated” or Cas genes. Together, they form the “CRISPR-Cas system,” and the new paper describes this dynamic duo and how they protect bacteria from viruses.

“You can look at one as a police dog that tracks down and latches onto an invader, and the other as a police officer that follows along and `silences’ the offender,” said Rebecca Terns. “It functions like our own immune system, constantly watching for and neutralizing intruders. But the surveillance is done by tiny CRISPR RNAs rather than antibodies.”

What the team discovered was that a particular complex of CRISPR RNAs and a subset of the Cas proteins termed the RAMP module recognizes and destroys invader RNAs that it encounters.

“This work has uncovered intriguing parallels between the bacterial CRISPR-Cas system and the human immune system, suggesting a novel way to target disease-causing bacteria,” said Laurie Tompkins, Ph.D., who oversees genetic mechanisms grants at the National Institutes of Health’s National Institute of General Medical Sciences. “It may be possible to turn CRISPR-Cas into a suicide machine, killing pathogenic bacteria by an attack on their own molecules, similar to the self-destruction seen in human autoimmune diseases.”

Understanding how the system silences invaders opens up opportunities to exploit it. So far, CRISPRs have been found in about half of the bacterial genomes that have been mapped or sequenced and in nearly all sequenced archaeal genomes. Such pervasiveness indicates that an ability to manipulate the CRISPR-Cas system could yield a broad range of applications. For example, using the knowledge that they have obtained in this work, the Terns now envision being able to design new CRISPR RNAs that will take advantage of the system to selectively cleave target RNAs in bacterial cells.

“These could target viruses that wipe out cultures of bacteria used by industry to produce enzymes,” said Michael Terns, “or could target the gene products of the bacteria themselves. With this set of Cas proteins, we now know how to cut a target RNA at the site we choose.”

“Believe it or not, we have only recently recognized that these microorganisms have a heritable immune system [because it is so different from our own],” added Rebecca Terns.

Remarkably, scientists are already in a position to begin to capitalize on their rapidly growing knowledge of this bacterial immune system.

Story Source:

Adapted from materials provided by University of Georgia, via EurekAlert!, a service of AAAS.

http://www.sciencedaily.com/releases/2009/11/091125134703.htm

California’s Ancient Kelp Forest

Kelp beds are declining in their diversity, according to a new study. (Credit: Enric Sala/Scripps Institute of Oceanography)

The kelp forests off southern California are considered to be some of the most diverse and productive ecosystems on the planet, yet a new study indicates that today’s kelp beds are less extensive and lush than those in the recent past.

The kelp forest tripled in size from the peak of glaciation 20,000 years ago to about 7,500 years ago, then shrank by up to 70 percent to present day levels, according to the study by Rick Grosberg, professor in the Department of Evolution and Ecology and the Center for Population Biology at UC Davis, with Michael Graham of the Moss Landing Marine Laboratory and Brian Kinlan at UC Santa Barbara.

Kelp forests around offshore islands peaked around 13,500 years ago as rising sea levels created new habitat and then declined to present day levels. The kelp along the mainland coast peaked around 5,000 years later.

This transition from an extensive island-based kelp system to a mainland-dominated system coincided with conspicuous events in the archaeological record of the maritime people in the region, suggesting that climate-driven shifts in kelp ecosystems impacted human populations that used those resources.

Understanding the past history of a population is crucial to understanding its genetics in the present, Grosberg said.

“Kelp is interesting because it disperses only over short distances,” Grosberg said. “Populations can become genetically isolated from one another even if they are quite close together.”

“We wanted to know how connected the coastal kelp populations were since the last glacial maximum,” he said.

On land, scientists can reconstruct the history of a forest or grassland from fossilized pollen or leaves. But kelp do not make pollen, and marine sediments do not preserve a good record of the plants.

The researchers used depth charts of the southern California coastline and information from sediment cores on past nutrient availability to reconstruct potential kelp habitat as sea levels changed over the last 20,000 years.

“We could reconstruct changes in kelp cover at a scale of 500 years and determine how fragmented or connected the populations were,” Grosberg said.

People have lived off the produce of kelp forests when resources on land dwindled, and those changes are recorded in shell middens and other traces. That archaeological record can now be compared with the ecological history to get a more complete picture of California’s coast.

“Now we know what was happening with kelp, what was happening with the ecology on land, and what the people were doing,” Grosberg said.

The study was published online Oct. 21 in the journal Proceedings of the Royal Society B.

Story Source:

Adapted from materials provided by University of California – Davis.

http://www.sciencedaily.com/releases/2009/11/091111092049.htm