Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Looking for the heartbeat of cellular networks

18.12.2009
Optical approach measures molecular kinetics in living cells

Our cells' molecules form an intricate network of interactions. Today's techniques, however, can only be used to measure individual molecular reactions outside the cells. Since molecular concentrations are much higher in cells than in the laboratory, scientists suspect that the kinetics of molecular reactions in living cells differ substantially from external probes.

„We expected the cellular reaction speed to be higher," confirms LMU biophysicist Professor Dieter Braun. "However, our novel optical approach showed that – depending on the length of the strands – the coupling of DNA-strands inside living cells can be both faster and slower than outside."

Data yielded from living cells are highly valuable for the development of models to understand the complex interactions as well as pathological processes in biological cells. Braun and his team now plan to probe a variety of molecular reactions in living cells, visualizing the heartbeat of cellular networks. (PNAS online, 14 November 2009)

In their work, the scientists investigated the hybridization – the coupling and de-coupling – of two DNA-strands, which they introduced into living cells. To determine the reaction time constant they used an infrared laser to induce temperature oscillations of different frequencies in the cell and measured the concentration of the reaction partners, namely of coupled and de-coupled DNA. At low frequencies, these concentrations followed the temperature oscillations, whereas at higher frequencies they experienced a phase delay and oscillated with diminished amplitude. Both delay time and amplitude decrease, were evaluated to obtain the reaction time constant.

The team determined the concentrations using the so-called fluorescent energy transfer (FRET), which takes place between two chromophores at a certain spatial distance. They applied a FRET pair to the DNA-strands such that energy transfer occurred only if the strands were coupled. The chromophores were excited with a stroboscopic lamp and a CCD camera registered time and amplitude of the fluorescence, thus visualizing the concentration alterations with a spatial resolution of about 500 nanometres. The experiments revealed that DNA-strands comprising 16 units, the so-called bases, showed a sevenfold higher reaction speed compared to values determined outside living cells.

12-base DNA-strands, on the other hand, reacted times five times slower than outside cells. This is a surprising result, since kinetics of molecular reactions has been assumed to be always faster inside cells, where much higher molecular concentrations prevail. "Apparently cells modulate the reaction speed in a highly selective way," says Braun. "The measurements provide valuable insight into in vivo kinetic data for the systematic analysis of the complexity of biological cells," adds Ingmar Schön, who conducted the demanding experiments. The scientists are now planning to probe a wide variety of molecular reactions in living cells, visualizing the heartbeat of cellular networks. (CR/suwe)

Publication:
"Hybridization Kinetics is Different Inside Cells"
Ingmar Schoen, Hubert Krammer, Dieter Braun
PNAS online, 14 November 2009
Contact:
Prof. Dieter Braun
Systems Biophysics, Center for NanoScience (CeNS) and Cluster of Excellence "Nanosystems Initiative Munich" (NIM), LMU Munich
Phone: +49 (0) 89 / 2180 – 2317
E-Mail: dieter.braun@lmu.de

Professor Dieter Braun | EurekAlert!
Further information:
http://www.lmu.de

More articles from Life Sciences:

nachricht New technique unveils 'matrix' inside tissues and tumors
29.06.2017 | University of Copenhagen The Faculty of Health and Medical Sciences

nachricht Designed proteins to treat muscular dystrophy
29.06.2017 | Universität Basel

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 Waves

Computer scientists use wave packet theory to develop realistic, detailed water wave simulations in real time. Their results will be presented at this year’s SIGGRAPH conference.

Think about the last time you were at a lake, river, or the ocean. Remember the ripples of the water, the waves crashing against the rocks, the wake following...

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Nanostructures taste the rainbow

29.06.2017 | Physics and Astronomy

New technique unveils 'matrix' inside tissues and tumors

29.06.2017 | Life Sciences

Cystic fibrosis alters the structure of mucus in airways

29.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>