Biomechanics


Morphogenesis is an inherently mechanical event. There is an enourmous amount of cellular movement and cell shape change in the early embryo, driving the large scale rearrangement and reorganization of cell and tissues in the early embyro.  This requires that the cells coordinate to generate the forces driving these movements, the result of which forces depends on the biomechanical context (tissue geometry, stiffness) in which they are expressed.

We are trying to understand the biomechanics of early morphogenesis in amphibians, currently focusing on the frog Xenopus laevis, but also looking at salamander species of the Ambystoma genus.  We would like to determine: 1) how much force is expressed, when and by which tissues, 2) what the cell behavioral basis for force generation is, 3) the intra-cellular molecular mechanisms producing force, 4) the patterning mechanisms and inter-cellular mechanisms that coordinate that force, and 5) the intra- and inter-cellular basis of tissue stiffness.

Currently projects include a characterization of the forces that close the blastopore in Xenopus laevis, including those generated by the cell behaviors underlying Convergent Thickening and Convergent Extension, and measurements of the stiffness of the tissues involved.  We are also studying the biomechanics of Subduction in Ambystoma.

In conjunction with these biomechanical studies, we are looking at the role of Myosin in force and stiffness.






 

To answer these questions involve the application of several different techniques from high resolution imaging of cell behaviors using low-light digital microscopy, conventional and multiphoton timelapse confocal microscopy coordinated with the measurement of tissue stiffness and force generation.

 

Several approaches to understanding biomechanics in embryonic tissues.

schematic of tractor pull apparatus

Stress relaxation tests and force measurements of tissues using a "tractor pull apparatus" to measure stiffness and force generation.


Confocal timelapse sequences


Low-light digital microscopy