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Sunday, September 23, 2012
Saturday, September 22, 2012
Unusual symbiosis discovered in marine microorganisms
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Public release date: 21-Sep-2012[ | E-mail |
Share ] Contact: Cheryl Dybas
cdybas@nsf.gov
703-292-7734
National Science Foundation
Single-celled algae and nitrogen-fixing bacteria help fertilize the oceans
Scientists have discovered an unusual symbiosis between tiny single-celled algae and highly specialized bacteria in the ocean.
The partnership plays an important role in fertilizing the oceans by taking nitrogen from the atmosphere and "fixing" it into a form that other organisms can use.
Details of the finding, published in this week's issue of the journal Science, emerged from the investigation of a mysterious nitrogen-fixing microbe that has a very small genome.
First detected in 1998 by Jonathan Zehr, a marine scientist at the University of California, Santa Cruz (UCSC), the microbe now appears to be the most widespread nitrogen-fixing organism in the oceans.
It belongs to a group of photosynthetic bacteria known as cyanobacteria, but it lacks the genes needed to carry out photosynthesis.
Apparently its association with the algae makes those genes unnecessary.
"The cyanobacterium is a nitrogen-fixer, so it provides nitrogen to the host cell [the algae], and the host cell provides needed carbon to the cyanobacterium, which is lacking the machinery to get its own," says Anne Thompson, a lead author of the paper and researcher at UCSC. Rachel Foster of the Max Planck Institute for Marine Microbiology is the other lead author.
The finding has uncovered a symbiosis between two types of microorganisms that had remained hidden until now, says Matt Kane, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funded the research along with NSF's Division of Ocean Sciences.
"Genomic analysis indicates that the partnership between these organisms in some ways models the one that led to the evolution of plant organelles," says Kane.
This is an interesting symbiosis from an evolutionary perspective, says Zehr, "because it can be seen as analogous to an early stage in the endosymbiosis that led to chloroplasts in plants."
Chloroplasts, which carry out photosynthesis in all plants, evolved from symbiotic cyanobacteria that eventually were incorporated into host cells in a process known as endosymbiosis.
In previous work, Zehr's team had studied the cyanobacteria in samples processed at sea and brought back to the lab.
The researchers were able to sequence the microbe's complete genome. They discovered that it's missing the genes for several key metabolic pathways, suggesting that it might live in association with another organism.
The scientists were only able to see the symbiotic partners together when they sorted freshly collected seawater samples onboard a research vessel.
"Our collaborators at the University of Hawaii, Dave Karl and Ken Doggett, put a cell sorter into a portable laboratory--a lab in a box--so now we can take the machine to sea and sort cells that minutes before were in their natural environment," says Thompson. "That's how we found the association."
Zehr noted that it's difficult to estimate the contribution of this symbiosis to global carbon and nitrogen cycles.
Other algae are more abundant and may be more important in terms of the ocean's carbon cycle than the algae hosts in this symbiosis, he says. But the cyanobacteria partners likely make this a significant contribution to global nitrogen fixation in the oceans.
"Planktonic symbioses are very difficult to study," says Foster. "The associations are often fragile. Here we used multiple tools to identify one of the first examples of this kind of partnership in plankton."
###
In addition to Thompson, Zehr and Foster, the co-authors of the paper include Andreas Krupke, Niculina Musat and Marcel Kuypers of the Max Planck Institute for Marine Microbiology; Brandon Carter of UCSC; and Daniel Vaulot of the Station Biologique de Roscoff and the Pierre and Marie Curie University in Paris.
The research was also funded by the Gordon and Betty Moore Foundation and the Max Planck Society.
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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Public release date: 21-Sep-2012[ | E-mail |
Share ] Contact: Cheryl Dybas
cdybas@nsf.gov
703-292-7734
National Science Foundation
Single-celled algae and nitrogen-fixing bacteria help fertilize the oceans
Scientists have discovered an unusual symbiosis between tiny single-celled algae and highly specialized bacteria in the ocean.
The partnership plays an important role in fertilizing the oceans by taking nitrogen from the atmosphere and "fixing" it into a form that other organisms can use.
Details of the finding, published in this week's issue of the journal Science, emerged from the investigation of a mysterious nitrogen-fixing microbe that has a very small genome.
First detected in 1998 by Jonathan Zehr, a marine scientist at the University of California, Santa Cruz (UCSC), the microbe now appears to be the most widespread nitrogen-fixing organism in the oceans.
It belongs to a group of photosynthetic bacteria known as cyanobacteria, but it lacks the genes needed to carry out photosynthesis.
Apparently its association with the algae makes those genes unnecessary.
"The cyanobacterium is a nitrogen-fixer, so it provides nitrogen to the host cell [the algae], and the host cell provides needed carbon to the cyanobacterium, which is lacking the machinery to get its own," says Anne Thompson, a lead author of the paper and researcher at UCSC. Rachel Foster of the Max Planck Institute for Marine Microbiology is the other lead author.
The finding has uncovered a symbiosis between two types of microorganisms that had remained hidden until now, says Matt Kane, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funded the research along with NSF's Division of Ocean Sciences.
"Genomic analysis indicates that the partnership between these organisms in some ways models the one that led to the evolution of plant organelles," says Kane.
This is an interesting symbiosis from an evolutionary perspective, says Zehr, "because it can be seen as analogous to an early stage in the endosymbiosis that led to chloroplasts in plants."
Chloroplasts, which carry out photosynthesis in all plants, evolved from symbiotic cyanobacteria that eventually were incorporated into host cells in a process known as endosymbiosis.
In previous work, Zehr's team had studied the cyanobacteria in samples processed at sea and brought back to the lab.
The researchers were able to sequence the microbe's complete genome. They discovered that it's missing the genes for several key metabolic pathways, suggesting that it might live in association with another organism.
The scientists were only able to see the symbiotic partners together when they sorted freshly collected seawater samples onboard a research vessel.
"Our collaborators at the University of Hawaii, Dave Karl and Ken Doggett, put a cell sorter into a portable laboratory--a lab in a box--so now we can take the machine to sea and sort cells that minutes before were in their natural environment," says Thompson. "That's how we found the association."
Zehr noted that it's difficult to estimate the contribution of this symbiosis to global carbon and nitrogen cycles.
Other algae are more abundant and may be more important in terms of the ocean's carbon cycle than the algae hosts in this symbiosis, he says. But the cyanobacteria partners likely make this a significant contribution to global nitrogen fixation in the oceans.
"Planktonic symbioses are very difficult to study," says Foster. "The associations are often fragile. Here we used multiple tools to identify one of the first examples of this kind of partnership in plankton."
###
In addition to Thompson, Zehr and Foster, the co-authors of the paper include Andreas Krupke, Niculina Musat and Marcel Kuypers of the Max Planck Institute for Marine Microbiology; Brandon Carter of UCSC; and Daniel Vaulot of the Station Biologique de Roscoff and the Pierre and Marie Curie University in Paris.
The research was also funded by the Gordon and Betty Moore Foundation and the Max Planck Society.
[ | E-mail | Share ] ?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Source: http://www.eurekalert.org/pub_releases/2012-09/nsf-usd092112.php
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EU body backs Novartis' Galvus, Eucreas for diabetes indications
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5.4 quake rattles southern Mexico
MEXICO CITY ? An earthquake shook parts of southern Mexico on Saturday, causing buildings to sway gently in the capital but causing no immediate reports of damage.
The U.S. Geological Survey said the quake struck at 8:30 a.m. EDT with a magnitude of 5.4. It was centered about 16 miles north of Pinotepa Nacional, a city near the Pacific Coast, and about 210 miles south-southeast of Mexico City.
Mexico?s national seismology service initially calculated the magnitude of the quake as 5.8 and said it was centered southwest of Pinotepa Nacional.
Source: http://www.journalgazette.net/article/20120922/NEWS04/120929870/-1/NEWS09
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Patch Pets: Meet Jasper! - Canon-McMillan, PA Patch
Jasper is one of the older dogs at Animal Rescue League in Pittsburgh in need of a home where he can enjoy his senior years.
He was surrendered, but we don't have much background information on him.
He does appear to be house-trained and he walks nicely on leash. Jasper is almost 8 years old and therefore is a calmer, more settled dog.
He also doesn't need the same level of exercise as our younger dogs, which may be a plus for some people. If you appreciate the qualities of an older dog, stop by and meet Jasper.
For inquiries about him, you can contact Sue at adoptadog.pgh@gmail.com.
Jasper's adoption fee is $55.
Source: http://canon-mcmillan.patch.com/articles/patch-pets-meet-jasper
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PFT: Young downplays financial problems
APThe Wall Street Journal recently rattled off a variety of statistics regarding the performance of the replacement officials.? The metrics chosen, however, are grossly superficial, inherently misleading, and in one instance factually incorrect.
(Please, Florio, tell us what you really think.)
First, the ?audit? reviews the issue of replay review.? Coaches have thrown the red flag 29 times, an 11 percent increase over last year.? But only 31 percent of the calls have been overturned ? down from 52 percent in 2011 and 42 percent in 2010.? The article then claims that a ?challenge call sends the play to an upstairs booth, where it?s reviewed by an official who isn?t a replacement.?
With that statement alone, the entire article should be ignored.? Anyone who watches any amount of NFL football knows that, when the red challenge flag is thrown, the decision is made on the field by a referee.? And since the referee is now a replacement, the ?audit? ignores the reality that the percentage of calls overturned could be skewed by the fact that the replacement referee who reviews the call may be getting it wrong, too.? (The ?audit? also offers no stats at all regarding replays initiated by the booth, a procedure that applies in the final two minutes of each half, after any scoring play, and after any turnover.)
Second, the ?audit? says that, on average, the games are six minutes slower.? While explaining that the difference is not ?apocalyptic? (what a relief), it ignores the reality that one or two games that last a ridiculously long time make the entire system look bad.? That?s happening this year, all too often.
Third, the ?audit? looks at the number of flags thrown.? Through two weeks, the yellow flag has flown 470 times.? It?s a difference of 11 from last year.? (The article doesn?t say whether it?s 11 more or 11 less.)? Throwing around terms like ?consistency,? this portion of the ?audit? creates the false impression that, if the total number of flags are the same, the replacements must be doing an equivalent job.
Anyone with a functioning brain should be offended by that one.? Comparing raw data on the number of penalties sheds no light on whether the right decisions are being made.? The ?audit? tells us nothing about flags that were mistakenly thrown ? or about penalties that mistakenly weren?t called.
Fourth, the ?audit? claims that the replacements ?punish,? with an increase in pass interference and holding calls, along with a spike in personal fouls from four to 21.? (It?s a little hard to believe that through two weeks of the 2011 season there were only four personal fouls called.)? This glosses over the fact that the replacements aren?t calling illegal contact with receivers (a rule that doesn?t exist at lower levels of the sport), and that defensive backs apparently are continuing the forbidden pushing, pulling, and/or shoving after the ball is in the air ? which is when pass interference can be called.
Also, the increase in holding penalties could be a product of the fact that holding can be called on every play.? Astute officials call holding only when it occurs in the vicinity of the ball carrier; stuff away from the play doesn?t matter, and rarely is called by the regular officials.? Replacements may be calling it beyond the area of the man with the football.
Fifth, the ?audit? claims that the replacements are ignoring certain types of penalties, like illegal shift and illegal man downfield.? Again, this kind of basic ?analysis? tells us nothing.? Maybe teams are engaged in fewer illegal shifts.? Or maybe they?re sending fewer illegal linemen down the field.
All told, it was a useless exercise that makes the replacements look better than they really are.? And it?s hard not to wonder whether the Wall Street Journal came up with the various categories on their own, or whether the NFL instigated the exercise.? (Indeed, unless someone at the Journal did all of the counting of penalties by hand, the raw data could have come from only one place.)
Here are the two primary truths that this trumped-up ?audit? ignores.? First, the only way to know how the replacements are performing is to review the play-by-play grades that are generated by the league based on a review of coaching tape, and to compare those grade to the grades from the first two weeks of 2011.? After the first week of games, during which the replacements looked the part, acted the part, and sounded the part, the aftermath resulted in multiple sources telling PFT that the average officiating errors per game exceeded 30.? In contrast, the regular officials had average mistakes in the single digits.
Second, the replacement officials in Week Two failed the eyeball test.? So regardless of meaningless stats like those in the Journal article or relevant numbers like the actual grades generated by the league office, when the product coming through the TV looks and sounds different, people notice.
Then again, people still don?t care.? And until the NFL feels a pinch to the bottom line, the NFL won?t care, either.
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The original 'Twitter'? Tiny electronic tags monitor birds' social networks
ScienceDaily (Sep. 20, 2012) ? If two birds meet deep in the forest, does anybody hear? Until now, nobody did, unless an intrepid biologist was hiding underneath a bush and watching their behavior, or the birds happened to meet near a research monitoring station. But an electronic tag designed at the University of Washington can for the first time see when birds meet in the wild.
A new study led by a biologist at Scotland's University of St. Andrews used the UW tags to see whether crows might learn to use tools from one another. The findings, published last week in Current Biology, supported the theory by showing an unexpected amount of social mobility, with the crows often spending time near birds outside their immediate family.
The study looked at crows in New Caledonia, an archipelago of islands in the South Pacific. The crows are famous for using different tools to extract prey from deadwood and vegetation. Biologists wondered whether the birds might learn by watching each other.
The results, as reported by St. Andrews, revealed "a surprising number of contacts" between non-related crows. During one week, the technology recorded more than 28,000 interactions among 34 crows. While core family units of New Caledonian crows contain only three members, the study found all the birds were connected to the larger social network.
The new paper is the first published study using the UW tags to record animal social interactions.
"This is a new type of animal-tracking technology," said co-author Brian Otis, a UW associate professor of electrical engineering whose lab developed the tags. "Ecology is just one of the many fields that will be transformed with miniaturized, low-power wireless sensors."
Biologists normally tag animals with radio transmitters that broadcast at a particular frequency, and field researchers use a receiver to listen for that frequency and detect when the animal is present. An encounter between small animals would only be recorded if the researcher was nearby.
The UW system, called Encounternet, uses programmable digital tags that can send and receive pulses.
"Encounternet tags can monitor each other, so you can use them to study interactions among animals," said co-author John Burt, a UW affiliate professor of electrical engineering. "You can't even start to do that with other radio-tracking technology."
Other research groups are using the UW tags around the world. Researchers at the University of Windsor in Canada are using them to study mating behavior in Costa Rican long-tailed manikins; a researcher at Drexel University is using them to study the interaction between birds and army ants in Costa Rica; German researchers are putting the tags on sea lions in the Galapagos Islands to study their behavior as they pull up on beaches; and researchers in the Netherlands are studying the social behavior of great tits, a small woodland bird. "It's a big topic right now, the idea that animals have social networks," Burt said. He has been working with field biologists for the last three years to deploy the tags.
"There are other tags that can do proximity logging, but they're all very big and for larger animals. None is as small as Encounternet -- or even near to it."
The smallest of the UW tags weighs less than 1 gram (0.035 ounces) and can be used on animals as light as 20 grams (less than an ounce), about the weight of a sparrow.
Researchers attach the tags to birds with straps that degrade and harmlessly fall off after the battery dies. The tag records nearby pulses, and the signal strength gives an estimate of the other animal's distance.
A typical study using the system includes a few dozen tags and between 10 and 100 fixed base stations. When tagged animals pass a base station the data is transmitted wirelessly from the tag to the base station, and from there to the Internet. Researchers can also reprogram the tags remotely -- for example, they can look at initial results to see when there are few encounters happening, and turn the battery off during those times to conserve power.
Burt completed his doctorate at the UW in 2000, with a dissertation on birdsong communication and learning. He wished that there was a way to automatically monitor bird interactions in the wild, and in 2005 joined forces with Otis, an expert in small, lightweight, low-power electronics. Burt managed the project to develop the tags, with funding from the National Science Foundation, as a research scientist in Otis' group. This fall they founded Encounternet LLC in Portland, Ore., where Burt now lives. He is working to add a GPS component to record the location of encounters, and to add an accelerometer and other sensors that could detect an animal's behavior.
"People are excited about this because for the first time, it allows them to study smaller animal interactions and social networks on an incredibly fine scale," Burt said. "Social networks are turning out to be key to understanding many animal behaviors. People say Encounternet is the only thing they can find that can collect that information."
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The above story is reprinted from materials provided by University of Washington.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Christian Rutz, Zackory T. Burns, Richard James, Stefanie M.H. Ismar, John Burt, Brian Otis, Jayson Bowen, James J.H. St Clair. Automated mapping of social networks in wild birds. Current Biology, 2012; 22 (17): R669 DOI: 10.1016/j.cub.2012.06.037
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Source: http://feeds.sciencedaily.com/~r/sciencedaily/most_popular/~3/UtUhv3SJTuE/120920153113.htm
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