Mechanical characterization of Xenopus laevis oocytes using atomic force microscopy

Area of Science:

• Cellular mechanics
• Biophysics
• Developmental biology

Background:

• Cellular mechanical properties influence biological activities and disease states.
• Oocytes have a unique extracellular vitelline membrane (VM) impacting their mechanics.
• Understanding oocyte mechanics is vital for cell lifecycle studies, interactions, and disease diagnosis.

Purpose of the Study:

• To quantify the mechanical properties of Xenopus laevis oocytes.
• To determine the contribution of the vitelline membrane (VM) to oocyte stiffness.
• To model the mechanical behavior of the VM using finite element analysis.

Main Methods:

• Nanoindentation using atomic force microscopy (AFM) to measure Young's modulus.
• Comparative mechanical testing of intact oocytes versus oocytes with VM removed.
• Finite element (FE) simulations to model nanoindentation and VM mechanical behavior.

Main Results:

• Oocyte Young's modulus significantly decreased after VM removal.
• The VM is the primary determinant of oocyte shape and stiffness.
• FE simulations with VM Young's modulus of 20-60 MPa accurately predicted experimental force-displacement curves.

Conclusions:

• The vitelline membrane (VM) plays a critical role in maintaining oocyte mechanical integrity.
• AFM nanoindentation and FE modeling are effective tools for characterizing oocyte mechanics.
• VM's mechanical properties are essential for understanding oocyte structure and function.