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Apoptosis regulates notochord development in Xenopus
Marina A Malikova1, Melanie Van Stry, Karen Symes
1Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
Abstract:
The notochord is the defining characteristic of the chordate embryo and plays critical roles as a signaling center and as the primitive skeleton. In this study we show that early notochord development in Xenopus embryos is regulated by apoptosis. We find apoptotic cells in the notochord beginning at the neural groove stage and increasing in number as the embryo develops. These dying cells are distributed in an anterior to posterior pattern that is correlated with notochord extension through vacuolization. In axial mesoderm explants, inhibition of this apoptosis causes the length of the notochord to approximately double compared to controls. In embryos, however, inhibition of apoptosis decreases the length of the notochord and it is severely kinked. This kinking also spreads from the anterior with developmental stage such that, by the tadpole stage, the notochord lacks any recognizable structure, although notochord markers are expressed in a normal temporal pattern. Extension of the somites and neural plate mirrors that of the notochord in these embryos, and the somites are severely disorganized. These data indicate that apoptosis is required for normal notochord development during the formation of the anterior-posterior axis, and its role in this process is discussed.
Insights
Apoptosis regulates notochord development in Xenopus embryos. Inhibiting this cell death in explants doubles notochord length, but in embryos, it causes severe kinking and structural loss.
Area of Science:
- Developmental biology
- Cell biology
- Embryology
Background:
- The notochord is crucial for chordate embryonic development, acting as a signaling center and primitive skeleton.
- Its formation and elongation are key processes during early axis formation.
Purpose of the Study:
- To investigate the role of apoptosis in early notochord development in Xenopus embryos.
- To understand how programmed cell death influences notochord extension and patterning.
Main Methods:
- Observation of apoptotic cells within the notochord during Xenopus embryogenesis.
- Inhibition of apoptosis in axial mesoderm explants and whole embryos.
- Analysis of notochord length, structure, and marker expression.
- Assessment of somite and neural plate development.
Main Results:
- Apoptotic cells are present in the notochord from the neural groove stage, increasing with development in an anterior-posterior pattern.
- Inhibition of notochord apoptosis in explants leads to a doubling of notochord length.
- Conversely, in whole embryos, apoptosis inhibition results in a shorter, severely kinked notochord, with disorganized somites and neural plate.
Conclusions:
- Apoptosis is essential for normal notochord development and anterior-posterior axis formation in Xenopus.
- The spatial and temporal regulation of apoptosis is critical for proper notochord elongation and structural integrity.
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