How cells get a skeleton

Jun 10, 2013

The mechanism responsible for generating part of the skeletal support for the membrane in animal cells is not yet clearly understood. Now, Jean-François Joanny from the Physico Chemistry Curie Unit at the Curie Institute in Paris and colleagues have found that a well-defined layer beneath the cell outer membrane forms beyond a certain critical level of stress generated by motor proteins within the cellular system. These findings, which offer a new understanding of the formation of this so-called cortical layer, have just been published in the European Physical Journal E.

Active gels are ideal for modelling the similar material found in living cells' structure, made of a dynamic, filamentous scaffold. They are composed of components that take up energy and do directed work. Indeed, is fed into the cells' constituents and is transformed into mechanical work through the assembly of its internal filaments, made of a polymer called actin, and a protein that functions as a , called myosin. Both provide the active gel-like substance found in cells with a spontaneous tendency to contract. As a result, the cells can either maintain or change their shape, or even adhere, spread, divide and crawl.

In this study, the authors have created hydrodynamic models of active gels to model the cell cortex, whereby the active gel is polymerising at the surface and depolymerising throughout the gel as a whole. They first derived the equations providing a coarse-grained description of cortical dynamics, then calculated the configuration in which their model was in a steady state.

They found that for sufficiently high levels of contractile stress it consisted of a dense layer near the membrane, which abruptly cut off beyond a certain thickness. The key advance in their model is the inclusion of gel disassembly throughout the system, and the contractility due to molecular motors.

Explore further: Researchers find animals killed by anthrax leave behind enticing grasses for herbivores, allowing disease to spread

More information: J.-F. Joanny et al. (2013), The actin cortex as an active wetting layer, European Physical Journal E. DOI 10.1140/epje/i2013-13052-9

add to favorites email to friend print save as pdf

Related Stories

Scientists build 'mechanically active' DNA material

Oct 23, 2012

Artificial muscles and self-propelled goo may be the stuff of Hollywood fiction, but for UC Santa Barbara scientists Omar Saleh and Deborah Fygenson, the reality of it is not that far away. By blending their ...

Make or break for cellular tissues

May 16, 2012

In a study about to be published in the European Physical Journal E, French physicists from the Curie Institute in Paris have demonstrated that the behaviour of a thin layer of cells in contact with an unfavourable substr ...

Recommended for you

What happens when good genes get lost?

19 hours ago

Scientifically speaking, there is no bad DNA, though we like to blame it for unruly hair, klutziness or poor gardening skills. There is, however, junk DNA.

Plants prepackage beneficial microbes in their seeds

Sep 29, 2014

Plants have a symbiotic relationship with certain bacteria. These 'commensal' bacteria help the pants extract nutrients and defend against invaders – an important step in preventing pathogens from contaminating fruits and ...

User comments : 0