Long-predicted fluctuations in cell membranes observed for first time

August 9, 2012
Among the many types of shape change cell membranes undergo, thickness fluctuations (bottom right) have been among the most difficult to observe. NIST neutron scientists helped make observations of these fluctuations for the first time, an effort that may aid in the understanding of how pores form in the membrane. Credit: Nagao/NIST

(Phys.org) -- A long-standing mystery in cell biology may be closer to a solution thanks to measurements taken at the National Institute of Standards and Technology (NIST) and France's Institut Laue-Langevin (ILL), where scientists have observed changes in the thickness of a model cell membrane for the first time. The findings, which confirm that long-predicted fluctuations occur in the membranes, may help biologists understand many basic cellular functions, including how membranes form pores.

Every cell in your body is surrounded by a , a thin, flexible wall made of that maintains the integrity of the and the rest of the cell's interior. Cells need a way to take in nutrients and expel waste across the membrane, and generally this involves lodging special proteins in the membrane. These proteins form holes that can open and close, acting as gateways to the interior.

Before these proteins take their place in the membrane, they float freely about the cell's protoplasm. But just how the membrane—whose job, after all, is to form an otherwise impermeable barrier—allows these proteins to penetrate it in the first place is largely a mystery, though one clue might lie in its dynamic nature.

"The cell membrane is not a static barrier. It's always moving, its thickness fluctuating and waves rippling through it," says Michihiro Nagao of the NIST Center for Neutron Research (NCNR). "Some theories indicate that if a is near the interior of the membrane when it is moving in just the right way, this movement might allow the protein to work its way in somehow."

The research team constructed a set of artificial membranes and analyzed their movement with a spin echo machine, a very specialized device of which there are only a few in the world. After a lengthy measurement effort, the team eventually found that when warmed to around body temperature, the membrane thickness fluctuated by up to 8 percent roughly every 100 nanoseconds, or 30 times slower than for comparable nonbiological sheets.

"Some theories indicate that some form of motion like this must be happening for pores to form, so it's exciting to actually see them," says Paul Butler, also of the NCNR.

It will take time to understand completely the cause of the fluctuations, why they are so slow, and how they enable protein insertion, but Butler points out that knowledge of the speed and size of the fluctuations will be helpful in designing therapies to control dysfunction in membrane permeability, including the creation of undesirable pores that lead to cell death.

"This research gives us a tool with which we can measure the effect of potential therapeutic agents on the thickness ," Butler adds.

The operation of the instrument at NIST is funded in part by the National Science Foundation.

Explore further: Closer look at cell membrane shows cholesterol 'keeping order'

More information: *A.C. Woodka, P.D. Butler, L. Porcar, B. Farago and M. Nagao. Lipid bilayers and membrane dynamics: Insight into thickness fluctuations. Physical Review Letters, DOI: 10.1103/PhysRevLett.109.058102 , Vol. 9, Issue 5, Aug. 3, 2012.

Related Stories

How muscle cells seal their membranes

March 14, 2012

Every cell is enclosed by a thin double layer of lipids that separates the distinct internal environment of the cell from the extracellular space. Damage to this lipid bilayer, also referred to as plasma membrane, disturbs ...

Nanomaterials to Mimic Cells

August 23, 2005

Mimicking a real living cell by combining artificial membranes and nanomaterials in one construction is the aim of a new research grant at UC Davis. The Nanoscale Integrated Research Team grant, funded by the National Science ...

New findings awaken age-old anesthesia question

March 21, 2012

(PhysOrg.com) -- Why does inhaling anesthetics cause unconsciousness? New insights into this century-and-a-half-old question may spring from research performed at the National Institute of Standards and Technology. Scientists ...

Recommended for you

Lightning, with a chance of antimatter

November 22, 2017

A storm system approaches: the sky darkens, and the low rumble of thunder echoes from the horizon. Then without warning... Flash! Crash!—lightning has struck.

How the Earth stops high-energy neutrinos in their tracks

November 22, 2017

Neutrinos are abundant subatomic particles that are famous for passing through anything and everything, only very rarely interacting with matter. About 100 trillion neutrinos pass through your body every second. Now, scientists ...

Quantum internet goes hybrid

November 22, 2017

In a recent study published in Nature, ICFO researchers led by ICREA Prof. Hugues de Riedmatten report an elementary "hybrid" quantum network link and demonstrate photonic quantum communication between two distinct quantum ...

Enhancing the quantum sensing capabilities of diamond

November 22, 2017

Researchers have discovered that dense ensembles of quantum spins can be created in diamond with high resolution using an electron microscopes, paving the way for enhanced sensors and resources for quantum technologies.


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (2) Aug 09, 2012
Re: "Every cell in your body is surrounded by a cell membrane, a thin, flexible wall made of fatty molecules that maintains the integrity of the nucleus and the rest of the cell's interior."

By the way, cells are gels, and gels do not require a membrane to keep the cell contents in place. Gels are "sticky" enough to do that job without any need for a membrane. Think Jello.

We've known for decades now that huge percentages of the cell membranes in the functioning body are compromised, and yet they continue to operate just fine. We've even observed cells under microscopes split in two, and continue to move along as if nothing happened.

The notion that the cell's functionality resides in its membrane is far from a proven hypothesis. Ling and Pollack have made very eloquent arguments against it which have largely been ignored for many decades now.
not rated yet Sep 08, 2012
The favored weapon in the microbial world is a protein complex that punches a hole in the membrane of a cell. Holes mean death. http://en.wikiped..._complex Hannes is spouting pure gobbledygook.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.