Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Method Empowers Fluorescence Microscopy

05.11.2012
The ability of fluorescence microscopy to study labeled structures like cells has now been empowered to deliver greater spatial and temporal resolutions that were not possible before, thanks to a new method developed by Beckman Institute faculty member Gabriel Popescu and Ru Wang from his research group.
Using this method, the researchers were able to study the critical process of cell transport dynamics at multiple spatial and temporal scales and reveal, for the first time, properties of diffusive and directed motion transport in living cells.

Popescu leads the Quantitative Light Imaging Laboratory at Beckman, while Wang of the lab is first author on the paper reporting the method in Physical Review Letters. The new approach, called dispersion-relation fluorescence spectroscopy (DFS), labels molecules of interest with a fluorophore whose motion, the researchers write, “gives rise to spontaneous fluorescence intensity fluctuations that are analyzed to quantify the governing mass transport dynamics. These data are characterized by the effective dispersion relation.”

That ability to study the directed and diffusive transport characteristics of cellular dispersion through a wide range of temporal and spatial scales is more comprehensive than using just fluorescence microscopy. It provides more information than existing methods, such as fluorescence correlation spectroscopy (FCS), which is widely used for studying molecular transport and diffusion coefficients at a fixed spatial scale.

This study used DFS to focus on the cell cytoskeleton subunit actin and found that “the fluorescently labeled actin cytoskeleton exhibits active transport motion along a direction parallel to the fibers and diffusive on the perpendicular direction.” Those results, the researchers said, describe at what scale and when directed versus diffusive motion is taking place in the cell.

“So for the first time we think we’re able to tell those apart and the spatial scales at which each is dominant,” Popescu said.

“Some traditional methods are good at measuring local transport and some are good at measuring the larger scales,” Wang said. “Our method gives a fuller view of what happens inside the cell, to the patterns of traffic. So we can look at both the local scale and at larger scales, and ask at which scale the motion transitions from random to directed motion.”

Popescu said the multiplicity of scales the method offers over techniques like fluorescence correlated spectroscopy is key.

“It’s like looking from the moon at a highway system in North America and you’re trying to understand the traffic,” Popescu said. “There are so many paths and some cars are moving fast, some slow, some over short distances, some over large distances, and all of these things are happening at the same time. We are actually able to break that information down to these simple pieces that seem to represent a universal behavior for all the cells we measured.

“With local measurements, it’s actually difficult to measure all these complexities because you only have one point of measurement. That’s why we tried to search for a better way that also uses the spatial information of that traffic. I think we now have solved it.”

Such knowledge would be valuable for researchers interested in the basic science of cellular dynamics, as well as those working in biomedical research, such as in analysis of a drug’s effect on the body. This technique can be used with current fluorescence microscopy methods.

“I think that the beauty of this method is that you can use a commercial fluorescent microscope that is found everywhere to collect and analyze data in a very simple way,” Wang said. “You don’t need complicated expertise. Everyone can use it.”

The method relies on taking time-resolved sequential data from fluorescent spectroscopic microscopy images and transforming them using the Fourier transform. This computational method enables easier understanding of the image data, providing a different representation of the image. Taking advantage of the respective frequency domains of patterns in the data, as this method does, is especially useful for trying to understand cellular dynamics like transport.

“It turns out the laws of physics are actually best described in the frequency domain,” Popescu said. “The dispersion relation in all branches of physics connects spatial scales with temporal scales. For example, as things get smaller in space, in length if you like, they tend to move faster. A fly will move faster than an elephant.

“This dispersion relation tells you how much faster. If I make something twice as small, is it going to move twice as fast, or four times or eight times? This relationship basically tells you everything about that dynamic phenomenon. So for the first time we saw this universal transport behavior in a living system: a clear combination of diffusive transport, like Brownian motion, and directed, deterministic transport. As a general trend, we found that diffusion is dominant at short scales and directed transport at large distances.”

They have also used the method to study neurons in work with the Center for Emergent Behaviors of Integrated Cellular Systems (EBICS) at Illinois, a multi-university project aimed at building living, multi-cellular machines that address real-world problems. The revelations regarding directed versus diffusive transport could be especially useful in reaching that goal.

“The fact that we can tell where the deterministic and the random transport appears is actually very relevant for looking at cells as a machine,” Popescu said. “What makes a cell machine is actually this directed component because you cannot predict with accuracy Brownian motion, but you can predict this directed motion.”

The group collaborated with Peter Wang’s lab in that research. Popescu said the collaboration with Wang and EBICS is just one example of the potential of DFS to be useful in many areas.

“We are measuring neuron networks. We’ve already shared these results with the Center and they are very excited,” Popescu said. “This is a very broadly applicable method.”

Steve McGaughey | EurekAlert!
Further information:
http://www.illinois.edu

More articles from Life Sciences:

nachricht Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology

nachricht Migrating Cells: Folds in the cell membrane supply material for necessary blebs
23.11.2017 | Westfälische Wilhelms-Universität Münster

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>