Fig. S4. The D-V polarity of the embryo can be predicted from the shape of the animal blastomeres at the eight-cell stage. Use of the vital dye Nile Blue sulfate allows marking of the ventral side of an albino embryo in preparation for bisection at blastula. (A) Animal (top) view of a pigmented eight-cell embryo showing the shape of the ventral cells spreading in a butterfly pattern and dorsal cells extending toward the equator. (B) A similar cell-shape pattern was observed in albino embryos, allowing a ventral blastomere to be marked with 20 mg/mL Nile Blue sulfate. (C) This pattern allows reliable marking of the ventral (or dorsal) side at the eight-cell stage as illustrated by this stage-10 embryo showing a ventral Nile Blue mark. (D–F) Bisection experiment in which pigmented or albino embryos were bisected at the blastula stage into dorsal and ventral halves (pigmented embryos are shown here). The dorsal half rescales to form a smaller but perfectly patterned embryo, whereas the ventral half lacks axial structures. In albino bisected embryos, all presumptive dorsal halves formed an axis (n = 20), whereas in presumptive ventral halves, only one (n = 12) formed an axis. The amount of Nile Blue sulfate should be kept to a minimum as it can quench fluorescence. Although Nile Blue sulfate was used in this study, other lineage tracers may be preferable in future studies.
Image published in: Plouhinec JL et al. (2013)
Copyright © 2013. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.
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