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bicaudal-C is required for the formation of anterior neurogenic ectoderm in the sea urchin embryo.

Yaguchi S, Yaguchi J, Inaba K - Sci Rep (2014)

Bottom Line: Loss-of-function experiments reveal that BicC is required for serotonergic neurogenesis and for expression of ankAT-1 gene, which is essential for the formation of apical tuft cilia in the neurogenic ectoderm of the sea urchin embryo.In contrast, the expression of FoxQ2, the neurogenic ectoderm specification transcription factor, is invariant in BicC morphants.Because FoxQ2 is an upstream factor of serotonergic neurogenesis and ankAT-1 expression, these data indicate that BicC functions in regulating the events that are coordinated by FoxQ2 during sea urchin embryogenesis.

View Article: PubMed Central - PubMed

Affiliation: 1] Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan [2] Japanese Association for Marine Biology (JAMBIO).

ABSTRACT
bicaudal-C (bicC) mRNA encodes a protein containing RNA-binding domains that is reported to be maternally present with deflection in the oocytes/eggs of some species. The translated protein plays a critical role in the regulation of cell fate specification along the body axis during early embryogenesis in flies and frogs. However, it is unclear how it functions in eggs in which bicC mRNA is uniformly distributed, for instance, sea urchin eggs. Here, we show the function of BicC in the formation of neurogenic ectoderm of the sea urchin embryo. Loss-of-function experiments reveal that BicC is required for serotonergic neurogenesis and for expression of ankAT-1 gene, which is essential for the formation of apical tuft cilia in the neurogenic ectoderm of the sea urchin embryo. In contrast, the expression of FoxQ2, the neurogenic ectoderm specification transcription factor, is invariant in BicC morphants. Because FoxQ2 is an upstream factor of serotonergic neurogenesis and ankAT-1 expression, these data indicate that BicC functions in regulating the events that are coordinated by FoxQ2 during sea urchin embryogenesis.

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BicC is required for FoxQ2 function.The ankAT-1 gene and serotonin were not detected in BicC morphants (A, B) but were detected in the control (F, G). Inset in (A) showed no ankAT-1 gene expression in BicC-MO2 morphant to ensure the specificity of the morpholinos. (C) and (H) show a P4 antigen pattern detecting differentiated spicule cell lineage. The inset of (H) shows a P4 signal with DAPI staining in the body rod of a 48 h embryo because the P4 signal in the oral lobe at this stage is almost missing. (D) is a merged image of (B) and (C). (I) is a merged image of (G) and (H). (E) and (J) show the morphology of a BicC morphant and control, respectively, at 48 h. Double fluorescent in situ hybridization staining with foxQ2 (K, O) and lefty (L, P) in a BicC morphant (K–N) and control (O–R). (M) Merged image of (K) and (L). (Q) Merged image of (O) and (P). (N, R) DAPI staining shows the morphology with a merged image of (M) and (Q), respectively.
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f3: BicC is required for FoxQ2 function.The ankAT-1 gene and serotonin were not detected in BicC morphants (A, B) but were detected in the control (F, G). Inset in (A) showed no ankAT-1 gene expression in BicC-MO2 morphant to ensure the specificity of the morpholinos. (C) and (H) show a P4 antigen pattern detecting differentiated spicule cell lineage. The inset of (H) shows a P4 signal with DAPI staining in the body rod of a 48 h embryo because the P4 signal in the oral lobe at this stage is almost missing. (D) is a merged image of (B) and (C). (I) is a merged image of (G) and (H). (E) and (J) show the morphology of a BicC morphant and control, respectively, at 48 h. Double fluorescent in situ hybridization staining with foxQ2 (K, O) and lefty (L, P) in a BicC morphant (K–N) and control (O–R). (M) Merged image of (K) and (L). (Q) Merged image of (O) and (P). (N, R) DAPI staining shows the morphology with a merged image of (M) and (Q), respectively.

Mentions: To investigate the function of BicC during sea urchin embryogenesis, we injected morpholino oligonucleotide (BicC-MO) against BicC mRNA, by which we inhibited its translation, and observed embryonic development. Initially, we tried to microinject BicC-MO into the fertilized eggs, and the injected embryos showed delayed development but still had normal morphology as prism larvae with invaginated gut, whereas the control reached to early pluteus stage at 52 hours (see Supplementary Fig. S1 online). It is possible that the morpholino is not sufficient for interfering with the translation of the maternal message1. To efficiently inhibit the translation of maternal bicC mRNA, we microinjected BicC-MO into unfertilized eggs, stored the injected eggs at 4°C overnight and inseminated the next day. BicC morphants developed more slowly than control embryos, and the cleavage timing was delayed by almost 1 mitosis cycle during the early stages (data not shown). The blastocoel of morphants forms but is narrower than that of control embryos (Fig. 2). Gastrulation is never observed in the morphants (Fig. 2I, 3E).


bicaudal-C is required for the formation of anterior neurogenic ectoderm in the sea urchin embryo.

Yaguchi S, Yaguchi J, Inaba K - Sci Rep (2014)

BicC is required for FoxQ2 function.The ankAT-1 gene and serotonin were not detected in BicC morphants (A, B) but were detected in the control (F, G). Inset in (A) showed no ankAT-1 gene expression in BicC-MO2 morphant to ensure the specificity of the morpholinos. (C) and (H) show a P4 antigen pattern detecting differentiated spicule cell lineage. The inset of (H) shows a P4 signal with DAPI staining in the body rod of a 48 h embryo because the P4 signal in the oral lobe at this stage is almost missing. (D) is a merged image of (B) and (C). (I) is a merged image of (G) and (H). (E) and (J) show the morphology of a BicC morphant and control, respectively, at 48 h. Double fluorescent in situ hybridization staining with foxQ2 (K, O) and lefty (L, P) in a BicC morphant (K–N) and control (O–R). (M) Merged image of (K) and (L). (Q) Merged image of (O) and (P). (N, R) DAPI staining shows the morphology with a merged image of (M) and (Q), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215294&req=5

f3: BicC is required for FoxQ2 function.The ankAT-1 gene and serotonin were not detected in BicC morphants (A, B) but were detected in the control (F, G). Inset in (A) showed no ankAT-1 gene expression in BicC-MO2 morphant to ensure the specificity of the morpholinos. (C) and (H) show a P4 antigen pattern detecting differentiated spicule cell lineage. The inset of (H) shows a P4 signal with DAPI staining in the body rod of a 48 h embryo because the P4 signal in the oral lobe at this stage is almost missing. (D) is a merged image of (B) and (C). (I) is a merged image of (G) and (H). (E) and (J) show the morphology of a BicC morphant and control, respectively, at 48 h. Double fluorescent in situ hybridization staining with foxQ2 (K, O) and lefty (L, P) in a BicC morphant (K–N) and control (O–R). (M) Merged image of (K) and (L). (Q) Merged image of (O) and (P). (N, R) DAPI staining shows the morphology with a merged image of (M) and (Q), respectively.
Mentions: To investigate the function of BicC during sea urchin embryogenesis, we injected morpholino oligonucleotide (BicC-MO) against BicC mRNA, by which we inhibited its translation, and observed embryonic development. Initially, we tried to microinject BicC-MO into the fertilized eggs, and the injected embryos showed delayed development but still had normal morphology as prism larvae with invaginated gut, whereas the control reached to early pluteus stage at 52 hours (see Supplementary Fig. S1 online). It is possible that the morpholino is not sufficient for interfering with the translation of the maternal message1. To efficiently inhibit the translation of maternal bicC mRNA, we microinjected BicC-MO into unfertilized eggs, stored the injected eggs at 4°C overnight and inseminated the next day. BicC morphants developed more slowly than control embryos, and the cleavage timing was delayed by almost 1 mitosis cycle during the early stages (data not shown). The blastocoel of morphants forms but is narrower than that of control embryos (Fig. 2). Gastrulation is never observed in the morphants (Fig. 2I, 3E).

Bottom Line: Loss-of-function experiments reveal that BicC is required for serotonergic neurogenesis and for expression of ankAT-1 gene, which is essential for the formation of apical tuft cilia in the neurogenic ectoderm of the sea urchin embryo.In contrast, the expression of FoxQ2, the neurogenic ectoderm specification transcription factor, is invariant in BicC morphants.Because FoxQ2 is an upstream factor of serotonergic neurogenesis and ankAT-1 expression, these data indicate that BicC functions in regulating the events that are coordinated by FoxQ2 during sea urchin embryogenesis.

View Article: PubMed Central - PubMed

Affiliation: 1] Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan [2] Japanese Association for Marine Biology (JAMBIO).

ABSTRACT
bicaudal-C (bicC) mRNA encodes a protein containing RNA-binding domains that is reported to be maternally present with deflection in the oocytes/eggs of some species. The translated protein plays a critical role in the regulation of cell fate specification along the body axis during early embryogenesis in flies and frogs. However, it is unclear how it functions in eggs in which bicC mRNA is uniformly distributed, for instance, sea urchin eggs. Here, we show the function of BicC in the formation of neurogenic ectoderm of the sea urchin embryo. Loss-of-function experiments reveal that BicC is required for serotonergic neurogenesis and for expression of ankAT-1 gene, which is essential for the formation of apical tuft cilia in the neurogenic ectoderm of the sea urchin embryo. In contrast, the expression of FoxQ2, the neurogenic ectoderm specification transcription factor, is invariant in BicC morphants. Because FoxQ2 is an upstream factor of serotonergic neurogenesis and ankAT-1 expression, these data indicate that BicC functions in regulating the events that are coordinated by FoxQ2 during sea urchin embryogenesis.

Show MeSH