The chick Brachyury gene: developmental expression pattern and response to axial induction by localized activin

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• The Brachyury gene (T) is essential for axial development in mice, particularly notochord differentiation and posterior mesoderm formation.
• Understanding the function and regulation of Brachyury homologues provides insights into conserved mechanisms of embryonic patterning across vertebrates.

Purpose of the Study:

• To isolate and characterize the chick homologue of the Brachyury gene (Ch-T).
• To determine the expression pattern of Ch-T during chick embryogenesis.
• To investigate the role of activin A in Ch-T induction and its implications for axis formation.

Main Methods:

• Isolation and sequencing of the chick Brachyury homologue (Ch-T).
• Analysis of Ch-T expression patterns during various stages of chick embryogenesis.
• Experimental manipulation using localized activin A treatment on prestreak blastoderms.

Main Results:

• Ch-T is expressed in the epiblast, primitive streak, migrating mesoderm, notochord, and tail bud during embryogenesis.
• The expression pattern of Ch-T is highly conserved across vertebrates, suggesting conserved embryonic patterning mechanisms.
• Activin A treatment induced ectopic Ch-T expression and affected primitive streak formation, indicating its role in axis induction.

Conclusions:

• The chick Brachyury gene (Ch-T) plays a vital role in embryonic development, with conserved functions and expression patterns across vertebrates.
• Ch-T activation is an early response to axis-inducing signals, such as activin A, in vivo.
• These findings reinforce the importance of Brachyury in establishing the vertebrate body plan.