Navigation Links
Molecule by molecule, new assay shows real-time gene activity

Editor: Have a look at the videos: 1 & 2

Chemists at Harvard University have developed the first technique providing a real-time, molecule-by-molecule "movie" of protein production in live cells. Their direct observation of fluorescently tagged molecules in single cells -- providing striking real-time footage of the birth of individual new protein molecules inside -- greatly increases scientists' precision in probing genetic activity.

Using the new assay, described this week in the journal Science, researchers led by Harvard's X. Sunney Xie counted, one by one, protein molecules generated in small bursts within cells as multiple ribosomes bound to single copies of mRNA complete the process by which DNA, an organism's long-term genetic repository, yields its crop of proteins. These random, or stochastic, bursts of protein expression are described in detail in a separate paper Xie and colleagues present this week in Nature.

"Although central to life processes, the expression of many important genes takes place at very low levels, making it difficult or impossible to observe using current technologies," says Xie, professor of chemistry and chemical biology in Harvard's Faculty of Arts and Sciences. "Our experiments provide the most sensitive means to date of observing real-time activity of single molecules inside cells. This new technique could provide us with unprecedented insights into gene expression and many other fundamental biological processes in living cells." The central dogma of molecular biology holds that DNA is transcribed into mRNA, which is then translated into proteins. But several technical hurdles have hampered study of these key processes. Researchers' current understanding of this two-step pathway is built upon their averaging of genetic and biochemical activity across large populations of ce lls and molecules, masking the essential randomness of the process at the cellular level. Furthermore, much of our knowledge on the workings of the molecular machinery involved in gene expression comes from experiments done in vitro, rather than in living cells. Finally, the low sensitivity of current techniques for detecting gene expression has restricted analysis to highly expressed genes.

Xie's new assay addresses all three limitations. He and his colleagues melded a yellow fluorescent protein called Venus with Tsr, a hydrophobic membrane protein. The inclusion of the Tsr domain serves to anchor the fused protein to a cell's membrane, sidestepping the longstanding difficulty of imaging single proteins zipping about in cell cytoplasm, where diffuse fluorescent signals tend to be overwhelmed by background noise.

The gene coding for this combined protein was substituted for the well-studied lacZ gene in the Escherichia coli chromosome. When lacZ's regulatory machinery allows the modified gene to be converted into a handful of protein molecules, these Tsr-Venus hybrids migrate to the cell membrane, where each attaches firmly. The clearly visible flash from each Tsr-Venus molecule -- which when viewed across a population of cells looks somewhat akin to a sea of cellular paparazzi -- serves as an indication of that single protein molecule's production.

"Dr. Xie's experiments are the first to obtain quantitative, real-time information on protein expression in living cells at the single-molecule level," says Jeremy M. Berg, director of the National Institute of General Medical Sciences, which funded the work in part. "His imaging methods open up new possibilities for addressing fundamental questions about the precise events and factors involved in regulating these essential processes. This is exactly the sort of highly innovative research with broad applicability that the National Institutes of Health Director's Pioneer Award was created to suppor t."


Source:Harvard University

Related biology news :

1. DNA Molecules Used To Assemble Nanoparticles
2. Duke Chemists Isolating Individual Molecules Of Toxic Protein In Alzheimers, Parkinsons Disease
3. Molecule that usually protects infection-fighting cells may cause plaque deposits inside arteries
4. Successful Test Of Single Molecule Switch Opens The Door To Biomolecular Electronics
5. Touching Molecules With Your Bare Hands
6. Team Invents Device For Weighing Individual Molecules
7. Missing Receptor Molecule Causes Tumor Growth
8. Molecule does more than slice and dice RNA
9. Molecules in blood foretell development of preeclampsia
10. Molecule that destroys bone also protects it, new research shows
11. PCRM develops worlds first cruelty-free insulin assay
Post Your Comments:

(Date:10/29/2015)... , Oct. 29, 2015 Today, ... a partnership with 2XU, a global leader in ... a smart hat with advanced bio-sensing technology. The ... athletes to monitor key biometrics to improve overall ... partnership, the two companies will bring together the most ...
(Date:10/27/2015)... SAN JOSE, Calif. , Oct. 27, 2015 /PRNewswire/ ... human interface solutions, today announced that Google has adopted ... family of touch controller solutions to power its newest ... Nexus 6P by Huawei. --> ... ecosystem partners like Google to provide strategic collaboration in ...
(Date:10/26/2015)... 26, 2015  Delta ID Inc., a company focused ... and PC devices, announced its ActiveIRIS® technology powers the ... F-02H launched by NTT DOCOMO, INC in ... second smartphone to include iris recognition technology, after a ... F-04G in May 2015, world,s first smartphone to have ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... Studies reveal the differences in species of bacteria ... for more effective treatment for one of the most commonly ... --> --> Gum disease is one ... relatively little was understood about the bacteria associated with it ... researchers from the WALTHAM Centre for Pet Nutrition together with ...
(Date:11/25/2015)... DIEGO , Nov. 25, 2015 Orexigen® ... management will participate in a fireside chat discussion at ... New York . The discussion is scheduled ... .  A replay will be ... Media Contact:McDavid Stilwell  , Julie NormartVP, Corporate Communications ...
(Date:11/24/2015)... Calif. , Nov. 24, 2015 Cepheid ... will be speaking at the following conference, and invited ... New York, NY      Tuesday, December 1, 2015 ... New York, NY      Tuesday, December 1, 2015 ... Jaffray Healthcare Conference, New York, NY ...
(Date:11/24/2015)... QUEBEC CITY , Nov. 24, 2015 /PRNewswire/ - ... the request of IIROC on behalf of the Toronto ... this news release there are no corporate developments that ... price. --> --> ... --> . --> Aeterna Zentaris ...
Breaking Biology Technology: