Navigation Links
Scientists synthesize memory in yeast cells
Date:9/22/2007

BOSTON, Mass. (September 14, 2007)Harvard Medical School researchers have successfully synthesized a DNA-based memory loop in yeast cells, findings that mark a significant step forward in the emerging field of synthetic biology.

After constructing genes from random bits of DNA, researchers in the lab of Professor Pamela Silver, a faculty member in Harvard Medical Schools Department of Systems Biology, not only reconstructed the dynamics of memory, but also created a mathematical model that predicted how such a memory device might work.

Synthetic biology is an incredibly exciting field, with more possibilities than many of us can imagine, says Silver, lead author of the paper to be published in the September 15 issue of the journal Genes and Development. While this proof-of-concept experiment is simply one step forward, weve established a foundational technology that just might set the standard of what we should expect in subsequent work.

Like many emerging fields, theres still a bit of uncertainty over what, exactly, synthetic biology is. Ask any three scientists for a definition, and youll probably get four answers.

Some see it as a means to boost the production of biotech products, such as proteins for pharmaceutical uses or other kinds of molecules for, say, environmental clean-up. Others see it as a means to creating computer platforms that may bypass many of the onerous stages of clinical trials. In such a scenario, a scientist would type the chemical structure of a drug candidate into a computer, and a program containing models of cellular metabolism could generate information on how people would react to that compound.

Either way, at its core, synthetic biology boils down to gleaning insights into how biological systems work by reconstructing them. If you can build it, it forces you to understand it.

A team in Silvers Harvard Medical School lab led by Caroline Ajo-Franklin, now at Lawrence Berkeley National Laboratory, and postdoctoral scientist David Drubin decided to demonstrate that not only could they construct circuits out of genetic material, but they could also develop mathematical models whose predictive abilities match those of any electrical engineering system.

Thats the litmus test, says Drubin, namely, building a biological device that does precisely what you predicted it would do.

The components of this memory loop were simple: two genes that coded for proteins called transcription factors.

Transcription factors regulate gene activity. Like a hand on a faucet, the transcription factor will grab onto a specific gene and control how much, or how little, of a particular protein the gene should make.

The researchers placed two of these newly synthesized, transcription factor-coding genes into a yeast cell, and then exposed the cell to galactose (a kind of sugar). The first gene, which was designed to switch on when exposed to galactose, created a transcription factor that grabbed on to, and thus activated, the second gene.

It was at this point that the feedback loop began.

The second gene also created a transcription factor. But this transcription factor, like a boomerang, swung back around and bound to that same gene from which it had originated, reactivating it. This caused the gene to once again create that very same transcription factor, which once again looped back and reactivated the gene.

In other words, the second gene continually switched itself on via the very transcription factor it created when it was switched on.

The researchers then eliminated the galactose, causing the first synthetic gene, the one that had initiated this whole process, to shut off. Even with this gene gone, the feedback loop continued.

Essentially what happened is that the cell remembered that it had been exposed to galactose, and continued to pass this memory on to its descendents, says Ajo-Franklin. So after many cell divisions, the feedback loop remained intact without galactose or any other sort of molecular trigger.

Most important, the entire construction of the device was guided by the mathematical model that the researchers developed.

Think of how engineers build bridges, says Silver. They design quantitative models to help them understand what sorts of pressure and weight the bridge can withstand, and then use these equations to improve the actual physical model. We really did the same thing. In fact, our mathematical model not only predicted exactly how our memory loop would work, but it informed how we synthesized the genes.

For synthetic biology, this kind of specificity is crucial. If we ever want to create biological black boxes, that is, gene-based circuits like this one that you can plug into a cell and have it perform a specified task, we need levels of mathematical precision as exact as the kind that go into creating computer chips, she adds.

The researchers are now working to scale-up the memory device into a larger, more complex circuit, one that can, for example, respond to DNA damage in cells.

One day wed like to have a comprehensive library of these so-called black boxes, says Drubin. In the same way you take a component off the shelf and plug it into a circuit and get a predicted reaction, thats what wed one day like to do in cells.


'/>"/>

Contact: David Cameron
public_affairs@hms.harvard.edu
617-432-0442
Harvard Medical School
Source:Eurekalert

Related biology technology :

1. UW computer scientists fighting computer virus "Cold War"
2. Scientists find way to make human collagen in lab
3. Wisconsin scientists to be recognized for innovative biofuel technology
4. UW-Madison scientists to mimic nature for newest cancer drugs
5. UW scientists study strange material with communications potential
6. Scientists find nanotech method for examining cells
7. UW space scientists use Keck telescope to study wild weather of Uranus
8. UW computer scientists tout achievements and explain industry shortcomings
9. Facing shortage of U.S. scientists, UW wants to boost math enrollment
10. UW-Madison scientists find a key to cell division
11. TIP/UW Scientists Provide Mars Rover Commentary
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/27/2016)... Raleigh, NC (PRWEB) , ... June 27, 2016 ... ... a mission to bring innovative medical technologies, services and solutions to the healthcare ... development and implementation of various distribution, manufacturing, sales and marketing strategies that are ...
(Date:6/24/2016)... , June 24, 2016 Epic Sciences ... detects cancers susceptible to PARP inhibitors by targeting ... cells (CTCs). The new test has already been ... in multiple cancer types. Over 230 ... damage response pathways, including PARP, ATM, ATR, DNA-PK ...
(Date:6/23/2016)... 2016   Boston Biomedical , an industry ... to target cancer stemness pathways, announced that its ... Drug Designation from the U.S. Food and Drug ... including gastroesophageal junction (GEJ) cancer. Napabucasin is an ... cancer stemness pathways by targeting STAT3, and is ...
(Date:6/23/2016)... , June 23, 2016  The Prostate Cancer Foundation (PCF) ... precise treatments and faster cures for prostate cancer. Members of the Class of ... 15 countries. Read More About the Class of 2016 ... ... ...
Breaking Biology Technology:
(Date:6/15/2016)... , June 15, 2016 ... market report titled "Gesture Recognition Market by Application Market - Global ... 2016 - 2024". According to the report, the  global ... billion in 2015 and is estimated to grow ... 48.56 billion by 2024.  Increasing application ...
(Date:6/2/2016)... The Department of Transport Management (DOTM) ... million US Dollar project, for the , Supply ... Enrolment, and IT Infrastructure , to ... implementation of Identity Management Solutions. Numerous renowned international vendors participated ... was selected for the most compliant and innovative ...
(Date:5/20/2016)... , May 20, 2016  VoiceIt is ... partnership with VoicePass. By working together, ... experience.  Because VoiceIt and VoicePass take slightly different ... engines increases both security and usability. ... excitement about this new partnership. "This ...
Breaking Biology News(10 mins):