The purpose of this project is to identify genes positively and negatively regulated by signaling molecules that belongs to the TGFbeta superfamily.

Lateral view of a tailbud stage embryo probed for FoxF expression following egg micro-injection of a Mesp MO. FoxF expression was down-regulated in mesenchyme. Expression in trunk epidermal cells was not affected.

Lateral view of a mid tailbud stage embryo co-electroporated with Mesp-lacZ (red) and Hl-GATAa-WRPW and probed for FoxF (green) expression.
Construct Hl-GATAa-WRPW was used to disrup GATAa activity.

Original annotation:
In Hl-GATAa-WRPW embryos, TVC expression of FoxF was eliminated or significantly reduced while expression in adjacent lineages was not affected.

Lateral view of a mid tailbud stage embryo co-electroporated with Mesp-lacZ (red) and Ttf-GATAa-WRPW and probed for FoxF (green) expression. The construct Ttf-GATAa-DBD was used as a control.

Original annotation:
There was no detectable difference in the TVC expression of FoxF between Ttf-GATAa-WRPW and control embryos.

Sagittal section through a mid tailbud embryo in which Ets1/2-VP16 was overexpressed under control of the mesp driver.

Picture E: The green FoxF ISH signal was visualised using TSA-Fluorescein and the picture obtained by confocal laser scanning microscopy.

Picture E': In red, the position of the B7.5 progeny, visualised through mesp::LacZ electroporation and LacZ immunohistochemistry.

Picture E": overlay of D and D'. Note that the posterior B7.5 lineage have migrated into the trunk and formed supernumerary heart precursors and that all B7.5 progeny have now been transformed into FoxF-expressing TVC and that. The control picture (D, D', D") shows Fox F and B7.5 in a wild-type embryo.

Sagittal section through a mid tailbud embryo in which Ets1/2-WRPW was overexpressed under control of the mesp driver.

Picture F: the green FoxF ISH signal was visualised using TSA-Fluorescein and the picture obtained by confocal laser scanning microscopy.

Picture F': in red, the position of the B7.5 progeny, visualised through mesp::LacZ electroporation and LacZ immunohistochemistry.

Picture F": overlay of F and F'. Note that all B7.5 progeny have now been transformed into FoxF-negative tail muscle. The control picture (D, D', D") shows Fox F and B7.5 in a wild-type embryo.

Sagittal section through a mid tailbud embryo in which Mesp-VP16 was overexpressed under control of the mesp driver.

Picture G: the green FoxF ISH signal was visualised using TSA-Fluorescein and the picture obtained by confocal laser scanning microscopy.

Picture G': in red, the position of the B7.5 progeny, visualised through mesp::LacZ electroporation and LacZ immunohistochemistry.

Picture G": overlay of G and G'. Note that B7.5 lineage cells that failed to migrate into the trunk did not express FoxF. The control picture (D, D', D") shows Fox F and B7.5 in a wild-type embryo.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the late gastrula stage (6hpf). FoxF enhancer drives RFP expression in the epidermis and in one trunk ventral cell precursor cell.
Original annotation: One B7.5 lineage cell on the right side expresses FoxF-RFP (line) and one on the left appears to undergo partial migration (arrow).

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the late gastrula stage (6hpf). Mesp enhancer drives GFP expression the B7.5 lineage.
Original annotation: One B7.5 lineage cell on the right side expresses FoxF-RFP (line) and one on the left appears to undergo partial migration (arrow).

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the late gastrula stage (6hpf). Mesp-driven GFP staining is observed in the B7.5 lineage.
(B) Green channel.
(B') Red channel.
(B'') Red and green channels

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the late gastrula stage (6hpf). FoxF enhancer drives RFP expression in the epidermis.
Original annotation: When gastrulating embryos were treated with the MEK inhibitor, U0126, the rostral cells fail to activate the FoxF enhancer.
(B) Green channel.
(B') Red channel. Note FoxF reporter expression in the epidermis (FoxF is expressed in both heart precursors and epidermis in WT embryos.)
(B'') Red and green channels.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the neurula stage (7hpf). Mesp enhancer drives GFP expression in the B7.5 lineage.
Original annotation: Although U0126 blocked heart induction up to the late gastrula stage, application at later time points (7–9hpf) failed to block induction.
(C) Green channel.
(C') Red channel.
(C'') Red and green channels.

Lateral view of a WT Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the neurula stage (7hpf). FoxF enhancer drives RFP expression in epidermis and trunk ventral cells.
Original annotation: Although U0126 blocked heart induction up to the late gastrula stage (6hpf) application at later time points (7–9H) failed to block induction.
(C) Green channel.
(C') Red channel.
(C'') Red and green channels.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and Mesp>FGFR-DN. Mesp enhancer drives GFP expression in the B7.5 lineage.
Original annotation: Targeted expression of FGFRDN in the B7.5 lineage blocks migration of the anterior heart precursors.
(F) Red channel.
(F') Red and green channels.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and Mesp>FGFR-DN. FoxF enhancer drives RFP expression in the epidermis.
Original annotation: Targeted expression of FGFRDN in the B7.5 lineage blocks migration of the anterior heart precursors and prevents activation of the FoxF enhancer in these cells.
(F) Red channel.
(F') Red and green channels.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and Mesp>Ets1/2-WRPW. Mesp enhancer drives GFP expression in the B7.5 lineage.
Original annotation: The repressor form, EtsWRPW, causes a block in heart migration, so that both the anterior and posterior B7.5 lineages remain in the tail.
(F) Red channel.
(F') Red and green channels.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and Mesp>Ets1/2-WRPW. FoxF enhancer drives RFP expression in the head epidermis.
Original annotation: The repressor form, EtsWRPW, causes a block in heart migration, so that both the anterior and posterior B7.5 lineages remain in the tail. The anterior lineage fails to activate the FoxF enhancer.
(F) Red channel.
(F') Red and green channels.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and Mesp>Ets1/2-VP16. Mesp enhancer drives GFP expression in the B7.5 lineage.
Original annotation: Targeted expression of constitutively active Ets1/2 (EtsVp16) in the B7.5 lineage doubles the number of heart progenitor cells by transforming the proximal tail muscle lineage into supernumerary heart cells.
(D) Red channel.
(D') Red and green channels.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and Mesp>Ets1/2-VP16. FoxF enhancer drives RFP expression in the B7.5 lineage.
Original annotation: A constitutively activated form of Ets1/2, EtsVp16, activate the FoxF enhancer in the whole B7.5 lineage.
(D) Red channel.
(D') Red and green channels.

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the late gastrula stage (6hpf). FoxF enhancer drives RFP expression in the epidermis and in one trunk ventral cell precursor cell.
Original annotation: One B7.5 lineage cell on the right side expresses FoxF-RFP (line) and one on the left appears to undergo partial migration (arrow).

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the late gastrula stage (6hpf). Mesp enhancer drives GFP expression the B7.5 lineage.
Original annotation: One B7.5 lineage cell on the right side expresses FoxF-RFP (line) and one on the left appears to undergo partial migration (arrow).

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the late gastrula stage (6hpf). Mesp-driven GFP staining is observed in the B7.5 lineage.
(B) Green channel.
(B') Red channel.
(B'') Red and green channels

Lateral view of a Ciona robusta mid tailbud stage embryo co-electroporated with Mesp>GFP (green) and FoxF>RFP (red) reporter constructs and treated with the MEK inhibitor U0126 at the late gastrula stage (6hpf). FoxF enhancer drives RFP expression in the epidermis.
Original annotation: When gastrulating embryos were treated with the MEK inhibitor, U0126, the rostral cells fail to activate the FoxF enhancer.
(B) Green channel.
(B') Red channel. Note FoxF reporter expression in the epidermis (FoxF is expressed in both heart precursors and epidermis in WT embryos.)
(B'') Red and green channels.

Dorsal confocal projections (Anterior to the left) of a Ciona robusta embryo electroporated with Mesp>GFP (green) and FoxF>RFP (red), arrested at the 110-cell stage (4hpf) through treatment with cytochalasin and fixed at 10hpf and treated with the MEK inhibitor U0126 from 16-cell stage (2hpf).
The Mesp enhancer drives GFP expression in the B7.5 lineage.
Original annotation: Treatment of 4hpf embryos with cytochalasin causes a block in the division of the B7.5 blastomeres at the 110-cell stage.

Dorsal confocal projections (Anterior to the left) of a Ciona robusta embryo electroporated with Mesp>GFP (green) and FoxF>RFP (red), arrested at the 110-cell stage (4hpf) through treatment with cytochalasin and fixed at 10hpf and treated with the MEK inhibitor U0126 from 16-cell stage (2hpf).
The FoxF enhancer drives RFP expression in the epidermis.
Original annotation: Treatment of 4hpf embryos with cytochalasin causes a block in the division of the B7.5 blastomeres at the 110-cell stage. Note lack of FoxF-RFP expression in the B7.5 cells (marked by Mesp>GFP). Also note that FoxF>RFP expression is significantly stronger in the epidermis, indicating that RTK signaling normally represses epidermal expression in arrested embryos.

Ventral view of the head of a Ciona robusta late tailbud stage embryo co-electroporated with FoxF>RFP (red) reporter construct and Mesp>FGFR-DN::VENUS (green) overexpression construct. FoxF enhancer drives RFP staining in the epidermis. Trunk lateral cells (green) did not migrate.
Original annotation: The dominant-negative form of the FGF receptor (FGFRDN) causes a block in heart cell migration and differentiation when expressed throughout the heart field using the Mesp B7.5 enhancer.
(E) Green channel.
(E') Red channel.(E'') Red and green channels.

Ventral view of the head of a Ciona robusta late tailbud stage embryo co-electroporated with FoxF>RFP (red) reporter construct and Mesp>FGFR-DN::VENUS (green) and Mesp>Ets1/2-VP16 overexpression constructs. FoxF enhancer drives RFP staining in epidermis and migrating heart cell precursors (labelled in green by Mesp reporter construct).
Original annotation: Migration and FoxF reporter gene activity were restored when both constitutively active Ets (Ets-Vp16) and dominant negative FGFR were simultaneously expressed in the B7.5 lineage
(F) Green channel.
(F') Red channel.(F'') Red and green channels.