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Wnt affects symmetry and morphogenesis during post-embryonic development in colonial chordates.

Di Maio A, Setar L, Tiozzo S, De Tomaso AW - Evodevo (2015)

Bottom Line: Modulation of the Wnt signaling in either process has shown to result in unusual body axis phenotypes.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.Our 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.

View Article: PubMed Central - PubMed

Affiliation: School of Bioscience, University of Birmingham, Edgbaston, Birmingham, B19 2TT UK ; Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106 USA.

ABSTRACT

Background: 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. 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.

Results: In 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.

Conclusions: Our 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.

No MeSH data available.


Treatments with Wnt agonists induce changes on the A/P polarity of developing buds. Ventral views of B. schlosseri colonies (oozoids) incubated with 0.5 μM APL (top row), and control colonies incubated with DMSO (bottom row). The antero/posterior (A/P) axis of zooid (light blue), primary bud (dark blue), and secondary bud (yellow) are represented in both samples. (A-B) During the first few days of treatments, no major signs of axis alteration of budlets (arrows) are visible. (C) Starting from the second blastogenic cycle (N + 1, stage 9/8/3), clear morphological changes are visible throughout the whole animal. Ectopically growing secondary buds (highlighted by white dashed lines) are visible after the first and second blastogenic cycle (days 11 through 16 post incubation) with an altered axis orientation. (D) The heavy pigmentation and the different polarity of the budlets persist even approaching the take-over stage (N + 1, stage 9/8/5). Note that the budlets axes are now almost perpendicular to the axes of the primary buds compared to a parallel disposition of the control. (E) Three weeks later (N + 2, stage 9/8/2), primary buds are difficult to recognize due the massive alteration of the overall morphology whereas no secondary buds were found at this point. Now the heart (h) is centrally located compared to the control in (E’) situated on the left side. (A’ through E’) Control animals incubated with DMSO did not show any A/P polarity alteration throughout the three blastogenic cycles analyzed. BAR: 200 μm.
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Fig4: Treatments with Wnt agonists induce changes on the A/P polarity of developing buds. Ventral views of B. schlosseri colonies (oozoids) incubated with 0.5 μM APL (top row), and control colonies incubated with DMSO (bottom row). The antero/posterior (A/P) axis of zooid (light blue), primary bud (dark blue), and secondary bud (yellow) are represented in both samples. (A-B) During the first few days of treatments, no major signs of axis alteration of budlets (arrows) are visible. (C) Starting from the second blastogenic cycle (N + 1, stage 9/8/3), clear morphological changes are visible throughout the whole animal. Ectopically growing secondary buds (highlighted by white dashed lines) are visible after the first and second blastogenic cycle (days 11 through 16 post incubation) with an altered axis orientation. (D) The heavy pigmentation and the different polarity of the budlets persist even approaching the take-over stage (N + 1, stage 9/8/5). Note that the budlets axes are now almost perpendicular to the axes of the primary buds compared to a parallel disposition of the control. (E) Three weeks later (N + 2, stage 9/8/2), primary buds are difficult to recognize due the massive alteration of the overall morphology whereas no secondary buds were found at this point. Now the heart (h) is centrally located compared to the control in (E’) situated on the left side. (A’ through E’) Control animals incubated with DMSO did not show any A/P polarity alteration throughout the three blastogenic cycles analyzed. BAR: 200 μm.

Mentions: Within the first 48 to 72 h of incubation with the Wnt agonists APL and LiCl (cycle N), buds and adult zooids appeared regular (Figure 4A and B). The majority (82%, n = 22 colonies) went through take-over normally while other colonies (18%, n = 22) followed a shorter (5 days) cycle. However, during the N + 1 blastogenic cycle (stage 9/8/3), primary and secondary buds showed a drastic change of their A/P polarity together with increased pigmentation (Figure 4C). Although at the time of the incubation adult zooids kept a normal A/P axis (Figure 4A and A’), primary buds and budlets at N + 1 cycle developed a rounded fashion without the normal symmetry (Figure 4C and D). Later in the cycle (stage 9/8/5), the A/P axis of the budlet drastically changed from being almost parallel to that of the primary bud to being perpendicular to it (Figure 4D). Comparing treated and untreated colonies, we observed a totally different angle between primary and secondary bud axes demonstrating an abnormal development.Figure 4


Wnt affects symmetry and morphogenesis during post-embryonic development in colonial chordates.

Di Maio A, Setar L, Tiozzo S, De Tomaso AW - Evodevo (2015)

Treatments with Wnt agonists induce changes on the A/P polarity of developing buds. Ventral views of B. schlosseri colonies (oozoids) incubated with 0.5 μM APL (top row), and control colonies incubated with DMSO (bottom row). The antero/posterior (A/P) axis of zooid (light blue), primary bud (dark blue), and secondary bud (yellow) are represented in both samples. (A-B) During the first few days of treatments, no major signs of axis alteration of budlets (arrows) are visible. (C) Starting from the second blastogenic cycle (N + 1, stage 9/8/3), clear morphological changes are visible throughout the whole animal. Ectopically growing secondary buds (highlighted by white dashed lines) are visible after the first and second blastogenic cycle (days 11 through 16 post incubation) with an altered axis orientation. (D) The heavy pigmentation and the different polarity of the budlets persist even approaching the take-over stage (N + 1, stage 9/8/5). Note that the budlets axes are now almost perpendicular to the axes of the primary buds compared to a parallel disposition of the control. (E) Three weeks later (N + 2, stage 9/8/2), primary buds are difficult to recognize due the massive alteration of the overall morphology whereas no secondary buds were found at this point. Now the heart (h) is centrally located compared to the control in (E’) situated on the left side. (A’ through E’) Control animals incubated with DMSO did not show any A/P polarity alteration throughout the three blastogenic cycles analyzed. BAR: 200 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Fig4: Treatments with Wnt agonists induce changes on the A/P polarity of developing buds. Ventral views of B. schlosseri colonies (oozoids) incubated with 0.5 μM APL (top row), and control colonies incubated with DMSO (bottom row). The antero/posterior (A/P) axis of zooid (light blue), primary bud (dark blue), and secondary bud (yellow) are represented in both samples. (A-B) During the first few days of treatments, no major signs of axis alteration of budlets (arrows) are visible. (C) Starting from the second blastogenic cycle (N + 1, stage 9/8/3), clear morphological changes are visible throughout the whole animal. Ectopically growing secondary buds (highlighted by white dashed lines) are visible after the first and second blastogenic cycle (days 11 through 16 post incubation) with an altered axis orientation. (D) The heavy pigmentation and the different polarity of the budlets persist even approaching the take-over stage (N + 1, stage 9/8/5). Note that the budlets axes are now almost perpendicular to the axes of the primary buds compared to a parallel disposition of the control. (E) Three weeks later (N + 2, stage 9/8/2), primary buds are difficult to recognize due the massive alteration of the overall morphology whereas no secondary buds were found at this point. Now the heart (h) is centrally located compared to the control in (E’) situated on the left side. (A’ through E’) Control animals incubated with DMSO did not show any A/P polarity alteration throughout the three blastogenic cycles analyzed. BAR: 200 μm.
Mentions: Within the first 48 to 72 h of incubation with the Wnt agonists APL and LiCl (cycle N), buds and adult zooids appeared regular (Figure 4A and B). The majority (82%, n = 22 colonies) went through take-over normally while other colonies (18%, n = 22) followed a shorter (5 days) cycle. However, during the N + 1 blastogenic cycle (stage 9/8/3), primary and secondary buds showed a drastic change of their A/P polarity together with increased pigmentation (Figure 4C). Although at the time of the incubation adult zooids kept a normal A/P axis (Figure 4A and A’), primary buds and budlets at N + 1 cycle developed a rounded fashion without the normal symmetry (Figure 4C and D). Later in the cycle (stage 9/8/5), the A/P axis of the budlet drastically changed from being almost parallel to that of the primary bud to being perpendicular to it (Figure 4D). Comparing treated and untreated colonies, we observed a totally different angle between primary and secondary bud axes demonstrating an abnormal development.Figure 4

Bottom Line: Modulation of the Wnt signaling in either process has shown to result in unusual body axis phenotypes.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.Our 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.

View Article: PubMed Central - PubMed

Affiliation: School of Bioscience, University of Birmingham, Edgbaston, Birmingham, B19 2TT UK ; Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106 USA.

ABSTRACT

Background: 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. 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.

Results: In 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.

Conclusions: Our 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.

No MeSH data available.