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Weak bases inhibit cleavage and embryogenesis in amphibians and echinoderms
Abstract:
The action of weak bases was studied on the early embryonic development of a number of species. Gastrulation was disrupted in the frog, Xenopus laevis, the newt, Pleurodeles watlii, the sea urchins, Paracentrotus lividus and Sphaerechinus granularis and the starfish, Asterias rubens. This required only submillimolar amounts of either NH+4 (pH 9.0) or procaine (pH 8.2). At higher concentrations even early cell division was inhibited in all the species with furrow regression particularly noticeable in Xenopus eggs. A similar action of the weak bases on early development, the lack of any action at lower extracellular pH, and the counteracting action of NH+4 on acidity-induced disruption of sea urchin development, all implicate an elevation of intracellular pH. However, a more direct intracellular action of the weak bases cannot be ruled out.
Insights
Weak bases like ammonium and procaine disrupt early embryonic development across multiple species by affecting gastrulation and cell division. These effects suggest a mechanism involving increased intracellular pH.
Area of Science:
- Developmental biology
- Cell biology
- Biochemistry
Background:
- Early embryonic development is a critical process susceptible to environmental factors.
- Understanding the molecular mechanisms that regulate embryonic development is crucial for developmental biology.
Purpose of the Study:
- To investigate the effects of weak bases on early embryonic development in various species.
- To elucidate the potential role of intracellular pH in mediating these effects.
Main Methods:
- Exposure of early embryos (Xenopus laevis, Pleurodeles watlii, Paracentrotus lividus, Sphaerechinus granularis, Asterias rubens) to weak bases (NH4+, procaine) at specific pH levels.
- Observation and documentation of developmental processes, including gastrulation and cell division.
- Analysis of dose-dependent effects and pH-dependent responses.
Main Results:
- Submillimolar concentrations of weak bases disrupted gastrulation in all studied species.
- Higher concentrations inhibited early cell division, with notable furrow regression in Xenopus.
- Developmental disruption was pH-dependent, with reduced effects at lower extracellular pH.
- Ammonium ions counteracted acidity-induced developmental disruption in sea urchins.
Conclusions:
- Weak bases disrupt early embryonic development by likely increasing intracellular pH.
- While intracellular pH elevation is implicated, a direct intracellular action of weak bases cannot be excluded.
- These findings provide insights into pH regulation during early development and potential chemical disruptors.