Biomedical engineers teach bacteria to count

May 28, 2009

Biomedical engineers at Boston University have taught bacteria how to count. Professor James J. Collins and colleagues have wired a new sequence of genes that allow the microbes to count discrete events, opening the door for a host of potential applications, which could include drug delivery and sensing environmental hazards.

"This was probably the major application still to be addressed within : Can you count discrete events?" said Collins, who is also a Howard Hughes Medical Institute investigator and a Boston University William Fairfield Warren Distinguished Professor. "And now we've come up with two different designs to do this."

The research is detailed in an article, "Synthetic Gene Networks That Count," that appears in the May 29 issue of Science.

The young but burgeoning field of synthetic biology addresses biological research questions with an engineering approach. Researchers design and build networks of genes, splicing them into bacterial genomes to run specific tasks or manufacture desired molecules - a process akin to installing biological computer software. Though the field is rapidly advancing, the gene-based tools available to synthetic biologists remain limited.

Gene networks that give bacteria the ability to count could become powerful devices in the synthetic biology toolkit because they can be coupled to almost any other bacterial function or environmental cue that bacteria can sense, such as presence of a toxin or sunlight. In the future, bacteria might be set to self-destruct after a certain number of cell divisions or after a specified period of time.

"The fundamental application is as a safety mechanism," said Collins. "If you've engineered an organism to be released into the environment as a biosensor, or you've engineered an organism to go into your body to deliver a therapeutic, in many cases you want to ensure after a certain period of time that the organism is no longer in the environment or your body."

Collins' team designed two separate synthetic gene networks not found naturally in E. coli bacteria. Each uses a different method to make the bacteria count.

The first, the Riboregulated Transcriptional Cascade (RTC) synthetic gene network, counts by starting and stopping transcription and translation - the process by which a gene's instructions are executed - of a series of genes every time an event occurs. The researchers programmed the system so that after the third interruption, the network translates and transcribes the gene for a fluorescing protein, which is visible to researchers.

The second network, called DNA Invertase Cascade (DIC), works in an entirely different way. At the first event, such as the presence of a chemical, the first gene manufactures a protein that cannibalistically snips its own gene out of the network, flips it over and sticks it back in. Once the gene is backwards, it can no longer be transcribed - but an extra snippet of DNA the researchers attached to its tail acts as a bookmark, showing protein-making machinery where to resume work. Each successive flip-over counts another event, and the fluorescing protein is activated after the third one.

In both methods, researchers can move the genetic parts in these counters around to fit their needs. The network might be extended to count to higher numbers, or additional genes for fluorescing proteins might be added, for example, to glow red when the bacteria have counted to two, and green at three. The network's counting can be linked to any periodic signal from the outside world the bacteria can detect, or to an internal event, such as a protein only expressed at one point during each cell division.

Each counter has strengths. The RTC can count quickly and works best when events happen every 20 to 30 minutes. The DIC takes longer to execute its flipping action, so works best when the events being counted are long and have long gaps between them, such as periods of sunlight and darkness, to count days. The options for using the counters are nearly endless, say the researchers.

"These are such basic tools that it's really hard to say what thousand things they might be used for in the future," said Ari Friedland, a graduate student in Collins' lab and a co-author of the paper. "Consider computing - what does one transistor do for you? Not that much, but if you pack a few thousand onto a chip, then you really have some power. These are fundamental biocomputing devices."

Source: Boston University Medical Center

Filter


Move the slider to adjust rank threshold, so that you can hide some of the comments.


Display comments: newest first

jolenaphillo
May 29, 2009

Rank: not rated yet
How long before binairy processor will be replaced with bio-intelligence?

http://www.lust4asia.com
http://www.spunkjunks.com
Rank 5 /5 (7 votes)
Relevant PhysicsForums posts
  • Protease cleavage
    created1 hour ago
  • Pertubance in a model
    created8 hours ago
  • Cancer drugs and Alzheimer's, Oh my!
    created16 hours ago
  • Squishing cells
    created17 hours ago
  • Any books/articles for evolutionary stable strategy models in humans?
    createdFeb 09, 2012
  • Science behind the bore feeling?
    createdFeb 09, 2012
  • More from Physics Forums - Biology

More news stories

The power of estrogen -- male snakes attract other males

A new study has shown that boosting the estrogen levels of male garter snakes causes them to secrete the same pheromones that females use to attract suitors, and turned the males into just about the sexiest ...

Biology / Plants & Animals

created 6 hours ago | popularity 5 / 5 (2) | comments 0 | with audio podcast

Experts reveal how plants don't get sunburn

(PhysOrg.com) -- Experts at the University of Glasgow have discovered how plants survive the harmful rays of the sun.

Biology / Cell & Microbiology

created 6 hours ago | popularity 5 / 5 (2) | comments 0 | with audio podcast

Grass to gas: Researchers' genome map speeds biofuel development

Researchers at the University of Georgia have taken a major step in the ongoing effort to find sources of cleaner, renewable energy by mapping the genomes of two originator cells of Miscanthus x giganteus, a large perenn ...

Biology / Biotechnology

created 3 hours ago | popularity 3.7 / 5 (3) | comments 0 | with audio podcast

Protein libraries in a snap

(PhysOrg.com) -- A Rice University undergraduate will depart with not only a degree but also a possible patent for his invention of an efficient way to create protein libraries, an important component of biomolecular ...

Biology / Cell & Microbiology

created 10 hours ago | popularity 5 / 5 (2) | comments 0 | with audio podcast

Miami battling invasion of giant African snails

No one knows how they got there. But an invasion of African giant snails has southern Florida in a panic over potential crop damage, disease and general yuckiness surrounding the slimy gastropods.

Biology / Ecology

created 10 hours ago | popularity not rated yet | comments 2


Complex wiring of the nervous system may rely on a just a handful of genes and proteins

Researchers at the Salk Institute have discovered a startling feature of early brain development that helps to explain how complex neuron wiring patterns are programmed using just a handful of critical genes. ...

CIA website offline, Anonymous takes credit

The website of the Central Intelligence Agency was unresponsive on Friday after the hacker group Anonymous claimed to have knocked it offline.

Q&A: Obama and the birth control controversy

(AP) -- What birth control debate? A half-century after the introduction of the pill, acceptance of birth control by American women is virtually universal.

New error-correcting codes guarantee the fastest possible rate of data transmission

Error-correcting codes are one of the triumphs of the digital age. They’re a way of encoding information so that it can be transmitted across a communication channel — such as an optical fiber o ...

Humans may have helped the decline of African rainforests 3000 years ago

(PhysOrg.com) -- Large areas of rainforests in Central Africa mysteriously disappeared over three thousand years ago, to be replaced by savannas. The prevailing theory has been that the cause was a change ...

Both maternal and paternal age linked to autism

Older maternal and paternal age are jointly associated with having a child with autism, according to a recently published study led by researchers at The University of Texas Health Science Center at Houston (UTHealth).