Ionophore-induced cell shape changes in Xenopus early embryos

Area of Science:

• Developmental Biology
• Cell Biology
• Amphibian Embryology

Background:

• Cell shape is crucial for embryonic development.
• Calcium ions play significant roles in cellular processes.
• The ionophore A23187 is a tool to study calcium's effects.

Purpose of the Study:

• To investigate the effects of the calcium ionophore A23187 on Xenopus ectoderm cell shape.
• To determine the involvement of microfilaments and extracellular calcium in ionophore-induced cell shape changes.

Main Methods:

• Local application of Ca++ ionophore A23187 to Xenopus early neurulae.
• Observation of cell shape changes in ectoderm.
• Experiments conducted in the presence of cytochalasin-B.
• Experiments performed in calcium- and magnesium-free medium with EDTA.
• Testing calcium antagonists D-600 and TMB-8.

Main Results:

• A23187 induced ectoderm cells to become rounded and form microvilli.
• Cell shape changes occurred even with cytochalasin-B, indicating no microfilament involvement.
• Ionophore effects persisted in Ca++- and Mg++-free medium, suggesting extracellular calcium is not required.
• Calcium antagonists did not inhibit the ionophore's effects.

Conclusions:

• Calcium ionophore A23187 directly influences ectoderm cell morphology in Xenopus embryos.
• The observed cell shape changes are independent of microfilament function.
• Extracellular calcium influx is not the primary mechanism for A23187-induced cell shape modulation.