Brachyury null mutant-induced defects in juvenile ascidian endodermal organs.

Area of Science:

• Developmental Biology
• Genetics
• Marine Biology

Background:

• The brachyury gene is crucial for notochord development in various species.
• Understanding brachyury's role in ascidians like Ciona intestinalis provides insights into chordate development.
• ENU mutagenesis is a common method for generating genetic mutants in model organisms.

Purpose of the Study:

• To investigate the function of the brachyury gene in Ciona intestinalis.
• To characterize the developmental defects caused by loss-of-function mutations in brachyury.
• To explore the consequences of brachyury disruption on cell fate and tissue morphogenesis.

Main Methods:

• Isolation and characterization of a recessive ENU-induced short-tailed mutant in Ciona intestinalis.
• Analysis of notochord differentiation and morphogenesis in homozygous brachyury mutants.
• Histological and staining techniques to assess cell fate and tissue development.

Main Results:

• A recessive mutant with a premature stop codon in the brachyury gene was identified.
• Notochord development and morphogenesis were severely disrupted in mutant lines.
• Ectopic endoderm staining and stochastic cell fate transformations were observed in larvae; tail resorption and digestive tract defects occurred in post-metamorphic stages.

Conclusions:

• Loss of brachyury function in Ciona intestinalis leads to severe notochord defects.
• brachyury is essential for proper tail resorption and digestive tract development.
• brachyury deficiency can result in cell fate transformation and misincorporation into endodermal structures.