FORCE EXERTED BY THE CLEAVAGE FURROW OF SEA URCHIN EGGS

Area of Science:

• Developmental Biology
• Biophysics
• Cell Biology

Background:

• Cell division involves complex forces, particularly during cytokinesis.
• Understanding the mechanics of the contractile ring is crucial for cell biology.

Purpose of the Study:

• To quantify the forces exerted by the advancing cleavage furrow during sea urchin egg division.
• To determine the interfacial tension between ferrofluid and egg cytoplasm.
• To estimate the tension developed in the contractile element of the furrow cortex.

Main Methods:

• Injecting ferrofluid drops into dividing sea urchin eggs and analyzing their deformation.
• Utilizing magnetic fields to deform ferrofluid drops and determine interfacial tension.
• Measuring forces based on ferrofluid drop deformation and interfacial tension values.

Main Results:

• Ferrofluid drops deformed into hourglass shapes as the cleavage furrow advanced.
• The force applied to the drop increased during early cleavage and decreased later.
• Maximum forces ranged from 2.0 × 10-3 to 9 × 10-3 dyne, depending on the species and whether furrowing was arrested.

Conclusions:

• The study provides quantitative measurements of forces during sea urchin egg cytokinesis.
• The findings offer insights into the mechanical properties of the contractile ring.
• The method using ferrofluid drops is effective for measuring forces in biological systems.