Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Single gene lets bacteria jump from host to host

02.02.2009
All life — plants, animals, people — depends on peaceful coexistence with a swarm of microbial life that performs vital services from helping to convert food to energy to protection from disease.

Now, with the help of a squid that uses a luminescent bacterium to create a predator-fooling light organ and a fish that uses a different strain of the same species of bacteria like a flashlight to illuminate the dark nooks of the reefs where it lives, scientists have found that gaining a single gene is enough for the microbe to switch host animals.

The finding, reported this week (Feb. 1) in the journal Nature by a team of scientists from the University of Wisconsin-Madison, is important not only because it peels back some of the mystery of how bacteria evolved to colonize different animals, but also because it reveals a genetic pressure point that could be manipulated to thwart the germs that make us sick.

"It seems that every animal we know about has microbes associated with it," says Mark J. Mandel, the lead author of the study and a postdoctoral fellow in the UW-Madison School of Medicine and Public Health. "We pick up our microbial partners from the environment and they provide us with a raft of services from helping digestion to protection from disease."

In the Pacific, a species of bacteria known as Vibrio fischeri lives in luminescent harmony with two distinct hosts: the diminutive nocturnal bobtail squid and the reef-dwelling pinecone fish. In the squid, which feeds at night near the ocean surface, one strain of the bacterium forms a light organ that mimics moonlight and acts like a cloaking device to shield the squid from hungry predators below. In the pinecone fish, another strain of the bacterium colonizes a light organ within the animal's jaw and helps illuminate the dark reefs in which it forages at night. The fish light organ may also play a role in attracting the zooplankton that make up the pinecone fish's menu.

But how did a single species of bacteria come to terms with such different hosts?

Working in the UW-Madison laboratory of microbiologist Ned Ruby, Mandel and his colleagues scoured the genomes of the two different strains of V. fischeri and found that most of the bacterium's genetic architecture was conserved over the course of millions of years of evolutionary history, but with a key difference: The strain that colonizes the squid has a regulatory gene that controls other genes that lay down a biofilm that allows the microbe to colonize the animal's light organ.

"During squid colonization, this regulatory gene turns on a suite of genes that allow bacteria to colonize the squid through mucus produced by the animal," Mandel explains. "The mucus is the pathway to the light organ, but it also helps keep out the bad guys."

Both strains of bacteria, Mandel explains, have the same genes that produce the biofilms the bacterium needs to get established in its host. But the regulatory gene that sets the other biofilm genes in motion is absent in the strain that lives in the pinecone fish, the animal scientists believe was first colonized by V. fischeri before it moved in to the squid light organ when the squid family came onto the scene in the Pacific Ocean at least 30 million years ago.

"The regulatory gene entered the bacterium's lineage and allowed it to expand its host range into the squid," according to Mandel. "The bottom-line message of the paper is that bacteria can shift host range by modifying their capabilities with small regulatory changes."

The regulatory gene acquired by the bacterium, notes Ruby, is essentially a switch the organism uses to activate a set of genes that had been residing quietly in the V. fischeri genome. Such mechanisms, he says, are very likely at play in many other species of bacteria, including those that infect humans and cause illness.

"This is going to inform a question that has been around a long time in the area of pathogenesis," says Ruby. One line of thought is that "in order to become a pathogen, a whole suite of genes needs to be imported to a bacterium."

The new finding by his group, however, suggests that nature is far more parsimonious: Instead of requiring organisms to acquire many new genes to occupy a new host, the combination of a new regulatory gene and genes that already reside in a bacterium is enough to do the trick.

"Together, they can do something neither of them could do before. They can mix and match and open up new niches," says Ruby.

Knowing that a regulatory gene plays a key role in allowing an organism to fit a new host may prove useful in human medicine as many bacterial pathogens arose first in other animals before infecting humans. A single gene can be a much easier target for a drug or other intervention to prevent or mitigate infection, the Wisconsin scientists say.

Mark J. Mandel | EurekAlert!
Further information:
http://www.wisc.edu

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>