Long-predicted fluctuations in cell membranes observed for first time

Aug 09, 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: New approach to form non-equilibrium structures

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

Mar 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, ...

Nanomaterials to Mimic Cells

Aug 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

Mar 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. ...

Recommended for you

New approach to form non-equilibrium structures

4 hours ago

Although most natural and synthetic processes prefer to settle into equilibrium—a state of unchanging balance without potential or energy—it is within the realm of non-equilibrium conditions where new possibilities lie. ...

Nike krypton laser achieves spot in Guinness World Records

6 hours ago

A set of experiments conducted on the Nike krypton fluoride (KrF) laser at the U.S. Naval Research Laboratory (NRL) nearly five years ago has, at long last, earned the coveted Guinness World Records title for achieving "Highest ...

Chemist develops X-ray vision for quality assurance

10 hours ago

It is seldom sufficient to read the declaration of contents if you need to know precisely what substances a product contains. In fact, to do this you need to be a highly skilled chemist or to have genuine ...

The future of ultrashort laser pulses

10 hours ago

Rapid advances in techniques for the creation of ultra-short laser pulses promise to boost our knowledge of electron motions to an unprecedented level.

IHEP in China has ambitions for Higgs factory

Jul 23, 2014

Who will lay claim to having the world's largest particle smasher?. Could China become the collider capital of the world? Questions tease answers, following a news story in Nature on Tuesday. Proposals for ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

HannesAlfven
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.
barakn
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.