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 Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

Bodyguards in the gut have a chemical weapon

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>