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. 1996 Oct;38(5):537-547.
doi: 10.1046/j.1440-169X.1996.t01-4-00010.x.

Production of hyperdorsal larvae by exposing uncleaved Xenopus eggs to a centrifugal force directed from the animal pole to the vegetal pole

Kazuhiro Takano  1 , Mika Kikkawa  1 , Atsunori Shinagawa  1
Affiliations

Production of hyperdorsal larvae by exposing uncleaved Xenopus eggs to a centrifugal force directed from the animal pole to the vegetal pole

Kazuhiro Takano et al. Dev Growth Differ. 1996 Oct.

Abstract

Exposure of uncleaved Xenopus eggs to a centrifugal force directed from the animal pole to the vegetal pole produces larvae with enhanced dorsal structures, which resemble 'hyperdorso-anterior' larvae produced by D2 O-treatment at 0.3 normalized time (NT). Optimal conditions are 70 g for 6 min at 20% of the first cell cycle (0.2 NT). Exposure before removal of vegetal pole cortical cytoplasm, which we find has an effect of eliminating dorsal structures, protects eggs from losing their ability to form dorsal axial structures upon removal. In contrast, exposure after a slight ultraviolet (UV)-irradiation, which has virtually no effect on dorsal development, produces larvae with heavily reduced dorsal structures, which resemble 'ventralized' larvae produced by heavy UV-irradiation. Interestingly, none of these treatments prevents cortical rotation. Morphological and histological examinations reveal that exposure to the force causes displacement of both cortical and deep egg components from around the vegetal pole to subequatorial regions. We conclude that exposure to the centrifugal force enhances dorsal structures by displacing dorsal determinants from around the vegetal pole to subequatorial regions broader than normal. This is the first experiment in which displacement of egg components, by methods independent of the rotation, are shown to perturb larval body pattern.

Keywords: Xenopus laevis; axis specification; cortical rotation; dorsal determinants; hyperdorsalization.

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