Y.H. Wong, H. Wang, T. Ravasi, P.Y. Qian
PLoS One., 7(3):e33323, (2012)
In this study, we analyzed the metamorphosis of the marine bryozoan Bugula neritina.
We observed the morphogenesis of the ancestrula. We defined three
distinct pre-ancestrula stages based on the anatomy of the developing
polypide and the overall morphology of pre-ancestrula. We then used an
annotation based enrichment analysis tool to analyze the B. neritina
transcriptome and identified over-representation of genes related to
Wnt signaling pathways, suggesting its involvement in metamorphosis.
Finally, we studied the temporal-spatial gene expression studies of
several Wnt pathway genes. We found that one of the Wnt ligand, BnWnt10, was expressed spatially opposite to the Wnt antagonist BnsFRP
within the blastemas, which is the presumptive polypide. Down-stream
components of the canonical Wnt signaling pathway were exclusively
expressed in the blastemas. Bnβcatenin and BnFz5/8
were exclusively expressed in the blastemas throughout the
metamorphosis. Based on the genes expression patterns, we propose that BnWnt10 and BnsFRP
may relate to the patterning of the polypide, in which the two genes
served as positional signals and contributed to the polarization of the
blastemas. Another Wnt ligand, BnWnt6, was expressed in the
apical part of the pre-ancestrula epidermis. Overall, our findings
suggest that the Wnt signaling pathway may be important to the pattern
formation of polypide and the development of epidermis.