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Cell wall and rhizoid polarity in Pelvetia embryos
D L Kropf1, H R Coffman, B Kloareg
1Department of Biology, University of Utah, Salt Lake City 84112.
Developmental Biology
|December 1, 1993
Summary
In Pelvetia embryos, neither the thallus nor rhizoid cell compensates for the loss of its sibling cell. Cell wall-plasma membrane interactions are crucial for maintaining rhizoid polar growth.
Area of Science:
- Developmental biology
- Cell biology
- Marine botany
Background:
- Early embryonic development in multicellular organisms relies on cell differentiation and pattern formation.
- Pelvetia embryos provide a model system to study the initial cell divisions and differentiation events.
Purpose of the Study:
- To investigate the developmental potential of individual cells in a two-celled Pelvetia embryo.
- To explore the role of cell-cell interactions and cell wall-plasma membrane connections in establishing cell polarity.
Main Methods:
- Micropipette aspiration for cell ablation (rhizoid or thallus removal).
- Laser irradiation to arrest cell division.
- Cell wall digestion and plasmolysis to separate protoplasts.
- Indirect immunofluorescence and confocal microscopy to visualize the cytoskeleton.
Main Results:
- Ablation or division arrest of one cell did not induce the other cell to compensate or dedifferentiate.
- Rhizoid cells lost their polar growth habit irreversibly after enzymatic cell wall digestion.
- Loss of rhizoid polarity correlated with disrupted microtubule organization.
- Transient plasmolysis induced rhizoid tip reorientation, suggesting plasticity.
Conclusions:
- The developmental fates of the rhizoid and thallus cells in early Pelvetia embryos are determined early and are not plastic.
- Cell wall-plasma membrane interactions are essential for maintaining the organized polar growth characteristic of rhizoid cells.