Control of cell differentiation and morphogenesis in amphibian development

Area of Science:

• Developmental Biology
• Molecular Biology
• Embryology

Background:

• Mesoderm induction is critical for amphibian embryogenesis.
• Activin and Fibroblast Growth Factor (FGF) are identified as key mesoderm-inducing factors in early Xenopus embryos.
• Follistatin, an activin-binding protein, is also present and may regulate activin activity.

Purpose of the Study:

• To review cell differentiation and morphogenesis driven by mesoderm-inducing factors during amphibian embryogenesis.
• To investigate the roles of activin and FGF in Xenopus development.
• To construct a model for organizer formation based on recent findings.

Main Methods:

• Review of existing literature on mesoderm induction.
• Experimental manipulation using activin and FGF.
• Injection of receptor mRNAs for activin and FGF to study endogenous actions.
• Use of dominant-negative receptors to disrupt signaling pathways.

Main Results:

• Activin induces various mesodermal tissues in a dose-dependent manner and can act as an organizer.
• Disruption of FGF signaling causes trunk and tail defects.
• Disruption of activin signaling prevents the formation of axial structures.
• Early prepatterns exist in Xenopus blastomeres, influencing their response to activin.

Conclusions:

• Activin and FGF are essential signaling molecules for mesoderm induction and pattern formation in amphibians.
• The interplay between inducing factors, competent cells, and regulatory proteins like follistatin is crucial for normal development.
• Understanding these inductive reactions is key to modeling organizer formation and subsequent organogenesis.