Abstract
BackgroundWnt signaling is one of the earliest and most highly conserved regulatory pathways for the establishment of the body axes during regeneration and early development. In regeneration, body axes determination occurs independently of tissue rearrangement and early developmental cues. Modulation of the Wnt signaling in either process has shown to result in unusual body axis phenotypes. Botryllus schlosseri is a colonial ascidian that can regenerate its entire body through asexual budding. This processes leads to an adult body via a stereotypical developmental pathway (called blastogenesis), without proceeding through any embryonic developmental stages.ResultsIn this study, we describe the role of the canonical Wnt pathway during the early stages of asexual development. We characterized expression of three Wnt ligands (Wnt2B, Wnt5A, and Wnt9A) by in situ hybridization and qRT-PCR. Chemical manipulation of the pathway resulted in atypical budding due to the duplication of the A/P axes, supernumerary budding, and loss of the overall cell apical-basal polarity.ConclusionsOur results suggest that Wnt signaling is used for equivalent developmental processes both during embryogenesis and asexual development in an adult organism, suggesting that patterning mechanisms driving morphogenesis are conserved, independent of embryonic, or regenerative development.Electronic supplementary materialThe online version of this article (doi:10.1186/s13227-015-0009-3) contains supplementary material, which is available to authorized users.
Highlights
Wnt signaling is one of the earliest and most highly conserved regulatory pathways for the establishment of the body axes during regeneration and early development
The same spatial cues regulated by the Wnt ligands during embryogenesis be used in post-embryonic developmental pathways, and Wnt has been shown to play a role during metamorphosis [18], during regeneration following injury [4,19], and in organisms that propagate asexually, including cnidarians [2,20,21], annelids [22], and ascidians [23]
Characterization of spatio-temporal Wnt expression during early blostogenetic cycle To assess the putative role of Wnt proteins in early developmental processes, we characterized gene expression patterns of B. schlosseri wnt orthologs during the first 3 days of secondary bud development by fluorescent in situ hybridization (FISH), prior to the onset of morphogenesis
Summary
Wnt signaling is one of the earliest and most highly conserved regulatory pathways for the establishment of the body axes during regeneration and early development. A major question in developmental biology is how symmetry in the early embryo is broken and body axes established to guide further development. These essential patterning mechanisms mainly occur during post-embryonic developmental process, such as metamorphosis or the regeneration of lost or damaged structures. The same spatial cues regulated by the Wnt ligands during embryogenesis be used in post-embryonic developmental pathways, and Wnt has been shown to play a role during metamorphosis [18], during regeneration following injury [4,19], and in organisms that propagate asexually, including cnidarians [2,20,21], annelids [22], and ascidians [23]. Whereas individuals of solitary ascidians grow in size and eventually reach sexual maturity, colonial forms grow via repeated rounds of asexual reproduction: following metamorphosis, a single founder individual (called oozooid) propagates asexually, eventually creating a colony of several to hundreds of individuals (called zooids), which are indistinguishable and genetically identical from the founder oozooid [26]
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