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Epithelial tissues show interesting physical properties such as glassiness and the associated dynamic heterogeneity.
Unlike other passive glasses, epithelia are active. Does biological activity alter glassy dynamics in epithelia? On the other hand, does the physical glassiness of the tissue affect its biological activity?
To answer these questions, I am studying the spatiotemporal dynamics of forces and mechanotransducer proteins in epithelia.
To study the spatiotemporal dynamics, we use experimental techniques such as timelapse imaging, traction force microscopy, monolayer stress micorscopy and immunostaining.
We then analyse the experimental data by image processing, cell segmentation and tracking, Particle Image velocimetry, Bayesian force inference etc.
During this journey, we have uncovered interesting clustering spatial patterns of proteins and forces, and oscillatory temporal dynamics.
Now, we are also exploring the role of spatiotemporal dynamics of proteins and forces in epithelia in epithelial tissue functions such as the extrusion of transformed cells and wound healing.
Below, I have tried to explain some of the above concepts without jargon to make my work accessible to non-specialists:
EPITHELIAL TISSUES
Epithelial tissues such as the skin, cover and protect our organs.
They are sheet-like with tightly packed cells, forming a physical barrier.
Mechanical forces in epithelia
Epithelial cells are connected to each other like holding hands. So, they can push and pull each other. We call this cell-cell forces.
They grow on top of a jelly-like substance called the ECM. They attach to the ECM and apply force on it to move. Like how we apply a backward force with our foot to move forward. We call this Traction.
Biochemical heterogeneity
Different cells of the tissue also have different protein levels- We call this biochemical heterogeneity.
This may be due to cell intrinsic noise in gene expression levels etc, or cell-extrinsic sources of noise such as asynchronous cell cycles.
Glassy dynamics
Usually, when a liquid is cooled slowly, its molecules have enough time to arrange themselves into an orderly, repeating pattern—this forms a crystalline solid, like ice or salt.
But if it is rapidly cooled, the molecules don’t get enough time to organize themselves properly. So, they form a glassy state which is an intermediate state between solids and liquids.
In glassy materials, the molecules are packed tightly. Because they’re so close together, each one is “caged in” by its neighbors, and they move with highly correlated velocitites.
This creates mesoscale regions of highly correlated velocities that may be fast or slow, called Dynamic heterogeneity.
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