Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Genetic master switch sends bacteria toward ’seafood dinner’

29.12.2003


Biologists unravel part of the mystery behind disappearance of shell material



Chitin, the Earth’s second-most abundant biological material, is a major component in the flurry of skeletal debris discarded daily by crustacean creatures in the world’s oceans. If left undisturbed, this tough insoluble material, a cousin to cellulose, would pile up on the ocean’s floor and wreak havoc with marine ecosystems. Fortunately, armies of bacteria act as chitin’s cleanup crew, and two Johns Hopkins University biologists have made a key discovery about how and when these microscopic soldiers launch their search-and-devour missions.

Writing in the Online Early Edition of "Proceedings of the National Academy of Sciences" for the week of Dec. 29, 2003, Xibing Li and Saul Roseman reported that they had found a genetic master switch that reacts to the presence of nearby chitin and sets off a biological chain reaction, causing the bacterial feast to begin. Understanding this process is important because 1011 tons of chitin (pronounced "KITE-in") are dumped annually in the oceans, largely by tiny sea animals called copepods, which shed their shells as they grow. "If nothing happened to this debris, we’d be up to our eyeballs in chitin, and the carbon and nitrogen cycle upon which marine life depends would be gone within 50 to 75 years," said Roseman, a professor of biology in the Kreiger School of Arts and Sciences at Johns Hopkins.


Researchers were puzzled about the disappearance of chitin because little of the material turned up in sediment on the ocean floors. Where did all of the chitin go? Then, about 70 years ago, two microbiologists determined that bacteria were quickly consuming the sinking shells and preserving the ecological balance. Since then, however, several mysteries have remained: How do the bacteria find these undersea meals? How do these microorganisms attach themselves to the chitin? How do they degrade the tough material and turn it into food?

During the past decade, Roseman and his colleagues have made several advances in answering these questions. In the new PNAS paper, Li and Roseman reported that they had identified and isolated the bacterial master switch that controls at least 50 and perhaps up to 300 other genes involved in the chitin sensing and consumption process. The biologists made their discovery by studying mutated versions of Vibrios, the ocean’s most common bacteria, which can cause illnesses such as cholera. The scientists separated and tested the mutant strains according to their ability to detect and break down chitin, then they analyzed the bacteria’s genetic structure to pinpoint the master switch.

"We believe," Roseman said, "that when the Vibrios are not in their feeding mode, this master switch remain in the ’minus’ or ’off’ position, locked in place by a binding protein. This keeps the cells from wasting energy by manufacturing proteins that won’t do them any good at that time."

Roseman added, "When the bacteria are starving, however, they secrete an enzyme called chitinase into the water. When chitinase touches the discarded shell material, it begins breaking down chitin, releasing a partially degraded soluble form into the water. These molecules are the signals to the bacteria that chitin is nearby. Diffusing through the ocean near the bacteria, these dissolved fragments of degraded chitin bind to the binding protein and remove the ’lock,’ allowing the master switch to move into a ’plus’ or ’on’ position."

When the switch is on, the bacteria’s genes get to work, moving the organisms along the trail of partially degraded chitin back to its source material, like a hungry traveler following the aroma of hot food to a roadside restaurant. In the ocean, the bacteria follow a gradient stream of higher and higher concentrations of dissolved degraded chitin until they reach the solid shell material. The bacteria then latch on and begin their feast.

"The master switch gene appears to be the key to this complex feeding process," said Li, an associate research scientist in the Department of Biology and lead author of the new paper. "This gives us a better understanding of the microscopic processes that keep our oceans from being overwhelmed by biological debris from sea creatures."

Phil Sneiderman | EurekAlert!
Further information:
http://www.bio.jhu.edu/
http://www.bio.jhu.edu/Directory/Faculty/Roseman/Default.html

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>