Neural crest lineage in the protovertebrate model Ciona

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Chordate Genomics

Background:

• Neural crest cells are crucial vertebrate progenitors, forming diverse cell types.
• Tunicates, such as Ciona, are evolutionarily close to vertebrates, making them ideal models for studying neural crest origins.
• Previous research identified potential neural crest derivatives in Ciona, but their homology remains debated.

Purpose of the Study:

• To investigate the evolutionary origins of neural crest cells.
• To determine if neural crest-like progenitor cells exist in tunicates.
• To understand the ancestral state of neural crest multipotency before vertebrate emergence.

Main Methods:

• Comparative genomics and developmental studies in the tunicate Ciona.
• Lineage tracing of pigment cells and analysis of neural progenitor formation.
• Examination of neural progenitor contribution to the juvenile nervous system post-metamorphosis.

Main Results:

• The pigment cell lineage in Ciona generates neural progenitor cells.
• These neural progenitors contribute to the tunicate nervous system after metamorphosis.
• This finding supports the homology of tunicate pigment cells to vertebrate neural crest derivatives.

Conclusions:

• A multipotent progenitor population, similar to vertebrate neural crest, existed at the neural plate border in the last common ancestor of tunicates and vertebrates.
• The key characteristic of neural crest multipotency predates the origin of vertebrates.
• This study sheds light on the deep evolutionary history of a fundamental vertebrate innovation.