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The prethalamus is established during gastrulation and influences diencephalic regionalization.

Staudt N, Houart C - PLoS Biol. (2007)

Bottom Line: In this study, we draw an extended expression map of the rostral neural plate that reveals discrete domains inside the presumptive posterior forebrain.Finally, transplantation of these precursors, in the rostral-most neural epithelium, induces changes in cell identity in the surrounding host forebrain.This cell-non-autonomous property led us to propose that these committed prethalamic precursors may play an instructive role in the regionalization of the developing diencephalon.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council Centre for Developmental Neurobiology, King's College London, London, United Kingdom.

ABSTRACT
The vertebrate neural plate contains distinct domains of gene expression, prefiguring the future brain areas. In this study, we draw an extended expression map of the rostral neural plate that reveals discrete domains inside the presumptive posterior forebrain. We show, by fate mapping, that these well-defined cell populations will develop into specific diencephalic regions. To address whether these early subterritories are already committed to restricted identities, we began to analyse the consequences of ablation and transplantation of these specific cell populations. We found that precursors of the prethalamus are already specified and irreplaceable at late gastrula stage, because ablation of these cells results in loss of prethalamic markers. Moreover, when transplanted into the ectopic environment of the presumptive hindbrain, these cells still pursue their prethalamic differentiation program. Finally, transplantation of these precursors, in the rostral-most neural epithelium, induces changes in cell identity in the surrounding host forebrain. This cell-non-autonomous property led us to propose that these committed prethalamic precursors may play an instructive role in the regionalization of the developing diencephalon.

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Schematic of the Uncaging Procedure(A) Caged fluorescein is injected into one-cell stage her5pac:egfp embryos. Injected embryos are kept in the dark until the fluorescein is uncaged in 6–10 cells of the diencephalic neural plate at bud stage using a laser beam. After further light-protected incubation, the embryos are fixed at prim5 stage, and the uncaged form of the fluorescein is detected via antibody staining.(B) Transverse section of a neural plate after the uncaging experiment, cells of the whole z-axis are labelled.(C) Result of labelling cells via uncaging in domain I, which correlates mostly with the expression pattern of barhl2 at bud stage.(D) At prim5, labelled areas in the diencephalon resemble the endogenous expression pattern of barhl2.
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pbio-0050069-g003: Schematic of the Uncaging Procedure(A) Caged fluorescein is injected into one-cell stage her5pac:egfp embryos. Injected embryos are kept in the dark until the fluorescein is uncaged in 6–10 cells of the diencephalic neural plate at bud stage using a laser beam. After further light-protected incubation, the embryos are fixed at prim5 stage, and the uncaged form of the fluorescein is detected via antibody staining.(B) Transverse section of a neural plate after the uncaging experiment, cells of the whole z-axis are labelled.(C) Result of labelling cells via uncaging in domain I, which correlates mostly with the expression pattern of barhl2 at bud stage.(D) At prim5, labelled areas in the diencephalon resemble the endogenous expression pattern of barhl2.

Mentions: Our expression map of the presumptive forebrain shows that cells located in the diencephalic territory differ already by their molecular constituents. To assess whether these molecular subdivisions match territories fated to become well-defined parts of the developing diencephalon, we performed fate-mapping studies of these specific cell populations, using the her5pac:egfp transgenic fish (permitting a high level of accuracy in cell targeting). We injected a caged form of fluorescein into one-cell stage her5pac:egfp transgenic embryos. Once the embryos reached bud stage, the fluorescein in 6–10 cells, within arbitrary domains, were uncaged using a laser beam (Figure 3A; see Materials and Methods). A cross section of the neural plate just after uncaging shows that cells have been labelled all along the z-axis (Figure 3B), indicating that our setup allows precision along the xy-axes, but not control of depth inside the neural plate. When uncaging broad areas of the diencephalic neural plate, we observe that cells inducing a specific early diencephalic marker tend to keep expressing it specifically through somitogenesis. Indeed, when we carefully label the barhl2 expression domain at bud stage, fluorescein is detected in a broad forebrain domain at prim 5, which closely resembles the expression pattern of barhl2 in the diencephalon at the same stage (Figure 3C and 3D).


The prethalamus is established during gastrulation and influences diencephalic regionalization.

Staudt N, Houart C - PLoS Biol. (2007)

Schematic of the Uncaging Procedure(A) Caged fluorescein is injected into one-cell stage her5pac:egfp embryos. Injected embryos are kept in the dark until the fluorescein is uncaged in 6–10 cells of the diencephalic neural plate at bud stage using a laser beam. After further light-protected incubation, the embryos are fixed at prim5 stage, and the uncaged form of the fluorescein is detected via antibody staining.(B) Transverse section of a neural plate after the uncaging experiment, cells of the whole z-axis are labelled.(C) Result of labelling cells via uncaging in domain I, which correlates mostly with the expression pattern of barhl2 at bud stage.(D) At prim5, labelled areas in the diencephalon resemble the endogenous expression pattern of barhl2.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC1808486&req=5

pbio-0050069-g003: Schematic of the Uncaging Procedure(A) Caged fluorescein is injected into one-cell stage her5pac:egfp embryos. Injected embryos are kept in the dark until the fluorescein is uncaged in 6–10 cells of the diencephalic neural plate at bud stage using a laser beam. After further light-protected incubation, the embryos are fixed at prim5 stage, and the uncaged form of the fluorescein is detected via antibody staining.(B) Transverse section of a neural plate after the uncaging experiment, cells of the whole z-axis are labelled.(C) Result of labelling cells via uncaging in domain I, which correlates mostly with the expression pattern of barhl2 at bud stage.(D) At prim5, labelled areas in the diencephalon resemble the endogenous expression pattern of barhl2.
Mentions: Our expression map of the presumptive forebrain shows that cells located in the diencephalic territory differ already by their molecular constituents. To assess whether these molecular subdivisions match territories fated to become well-defined parts of the developing diencephalon, we performed fate-mapping studies of these specific cell populations, using the her5pac:egfp transgenic fish (permitting a high level of accuracy in cell targeting). We injected a caged form of fluorescein into one-cell stage her5pac:egfp transgenic embryos. Once the embryos reached bud stage, the fluorescein in 6–10 cells, within arbitrary domains, were uncaged using a laser beam (Figure 3A; see Materials and Methods). A cross section of the neural plate just after uncaging shows that cells have been labelled all along the z-axis (Figure 3B), indicating that our setup allows precision along the xy-axes, but not control of depth inside the neural plate. When uncaging broad areas of the diencephalic neural plate, we observe that cells inducing a specific early diencephalic marker tend to keep expressing it specifically through somitogenesis. Indeed, when we carefully label the barhl2 expression domain at bud stage, fluorescein is detected in a broad forebrain domain at prim 5, which closely resembles the expression pattern of barhl2 in the diencephalon at the same stage (Figure 3C and 3D).

Bottom Line: In this study, we draw an extended expression map of the rostral neural plate that reveals discrete domains inside the presumptive posterior forebrain.Finally, transplantation of these precursors, in the rostral-most neural epithelium, induces changes in cell identity in the surrounding host forebrain.This cell-non-autonomous property led us to propose that these committed prethalamic precursors may play an instructive role in the regionalization of the developing diencephalon.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council Centre for Developmental Neurobiology, King's College London, London, United Kingdom.

ABSTRACT
The vertebrate neural plate contains distinct domains of gene expression, prefiguring the future brain areas. In this study, we draw an extended expression map of the rostral neural plate that reveals discrete domains inside the presumptive posterior forebrain. We show, by fate mapping, that these well-defined cell populations will develop into specific diencephalic regions. To address whether these early subterritories are already committed to restricted identities, we began to analyse the consequences of ablation and transplantation of these specific cell populations. We found that precursors of the prethalamus are already specified and irreplaceable at late gastrula stage, because ablation of these cells results in loss of prethalamic markers. Moreover, when transplanted into the ectopic environment of the presumptive hindbrain, these cells still pursue their prethalamic differentiation program. Finally, transplantation of these precursors, in the rostral-most neural epithelium, induces changes in cell identity in the surrounding host forebrain. This cell-non-autonomous property led us to propose that these committed prethalamic precursors may play an instructive role in the regionalization of the developing diencephalon.

Show MeSH
Related in: MedlinePlus