Indian Institute of Science researchers have examined the basic process that powers cell changes from the inside out.
HIGHLIGHTS
Various processes are governed by modifications in the geometry and topology of self-assembled membranes for cell transition.
A resolution of rod-shaped viruses had created the colloidal membranes.
The relative mobility (fluidity) of the individual lipid molecules and how this mobility varies with temperature are two characteristics of a lipid bilayer. The phase behaviour of the bilayer is the name given to this reaction. In general, a lipid bilayer can exist in either a liquid or a solid phase at a specific temperature. The term “gel” phase is frequently used to describe the solid phase. Every lipid has a specific temperature at which they change from the gel to liquid phase (melt).
An experiment developed by scientists at the Indian Institute of Science (IISc) has made it simpler for us to comprehend the process that causes changes in cell membranes. The transition is crucial for several biological processes like cell division, cell mobility, transport of nutrients into cells and viral infections.
Numerous processes in cellular biology and engineering are governed by modifications in the geometry and topology of self-assembled membranes. The study team has studied colloidal membranes, which are layers of aligned, rod-like particles that are only a few micrometres thick. These membranes offer a more manageable system to investigate since they share many of the same characteristics as cell membranes, which are fluidic sheets in which each component is free to diffuse rather than plastic sheets in which all the molecules are fixed.
According to a study that appeared in the journal Proceedings of the National Academy of Sciences, the experiment provides three-dimensional information about the process by which membranes change their topological shape in real-time.
A mixture of viruses with rod shapes and two different lengths—1.2 micrometres and 0.88 micrometers—was used to create the colloidal membranes. The group looked at how the morphology of the colloidal membranes changed as the proportion of short rods in the fluid increased. Ayantika Khanra, a Ph.D. candidate in the Department of Physics and the paper’s lead author, explains, “I produced many samples by combining varying quantities of the two viruses and then viewed them under a microscope.
The membranes changed from having a flat disc-like structure to having a saddle-like shape when the proportion of short rods was raised from 15% to between 20 and 35%, according to the IISc researchers, who also noted that over time, the membranes began to converge and expand in size.
“The number of ups and downs experienced as one travels along the saddle edge is used to classify saddles. The saddles generated a larger saddle of the same or higher order when they joined laterally, the researchers found, according to the release.
It did, however, remark that the final arrangement resembled a catenoid when they fused at an approximately straight angle and away from their edges. After that, the catenoids combined with other saddles to form more complicated structures like trinoids and four-noids.
Researchers have suggested a theoretical model to describe the behaviour of the membranes as it has been observed. “All physical systems tend to evolve towards low-energy structures, according to the rules of thermodynamics. A water droplet, for instance, takes on a spherical shape because it has less energy. This indicates that for membranes, geometries with shorter edges, like a flat disc, are preferred, according to the IISc.
The Gaussian curvature modulus is another characteristic that influences how the membrane is configured, the institution continued. The study’s demonstration that the membranes’ Gaussian curvature modulus rises as the proportion of short rods does was cited as a crucial finding.
This explains why adding more short rods made the membranes move toward lower-energy saddle-like forms. It also explains another finding from their experiment, which was that high-order membranes were large and low-order membranes were smaller in size.
“We have proposed a novel process for fluidic membrane curvature formation. According to Prerna, biological membranes may also use this method to adjust the curvature by varying the Gaussian modulus. She continues by saying that they intend to keep researching how additional microscopic alterations in the membrane’s constituent parts affect its large-scale characteristics.
