A force balance can explain local and global cell movements during early zebrafish development

Area of Science:

• Developmental Biology
• Cell Biology
• Biophysics

Background:

• Embryonic morphogenesis involves complex collective cell movements.
• Mechanisms coordinating these cellular transformations across an organism remain unclear.

Purpose of the Study:

• To investigate the role of physical forces in long-range intercellular coordination during zebrafish epiboly.
• To understand how mechanical forces influence blastoderm migration and axis reorientation.

Main Methods:

• Gentle mechanical deformation of developing zebrafish embryos.
• Chemical disruption of the actomyosin contractile ring using Ca(2+) reduction or blebbistatin.

Main Results:

• Geometric embryo distortion caused nonuniform blastoderm migration and anterior-posterior (AP) axis realignment.
• Local blastoderm migration rates correlated with local embryo geometry.
• Disrupting the actomyosin ring restored uniform migration and abolished AP axis reorientation.

Conclusions:

• Tension generated by the actomyosin ring coordinates epiboly at organismal and cellular scales.
• The anterior-posterior (AP) axis is distinct from the animal-vegetal axis in zebrafish embryos.