Axial rotation comprises concurrent twisting and bending as distinct morphogenetic components in Ciona

Area of Science:

• Developmental Biology
• Chordate Embryogenesis
• Morphogenesis

Background:

• Axial rotation (AR) is a key morphogenetic movement in chordates, essential for reshaping the body axis.
• The geometric details and regulatory mechanisms of AR are not fully understood.

Purpose of the Study:

• To dissect the components and regulatory mechanisms of axial rotation (AR) in the chordate Ciona robusta.
• To investigate the role of TGF-β signaling in AR.

Main Methods:

• Utilized Ciona robusta embryos for studying AR.
• Compared chorionated and dechorionated embryos.
• Inhibited TGF-β signaling using SB431542.
• Performed quantitative analysis of twisting angles.

Main Results:

• AR comprises distinct leftward bending and clockwise twisting components.
• Dechorionation randomized bending but not twisting direction.
• TGF-β inhibition randomized both bending and twisting.
• Twisting is intrinsically generated, while TGF-β signaling ensures global coordination.

Conclusions:

• Axial rotation in Ciona involves coordinated bending and twisting.
• TGF-β signaling plays a critical role in directing the global coordination of twisting during AR.
• Findings provide insights into the biomechanical and molecular basis of chordate body plan development.