Blastomere derivation and domains of gene expression in the Spemann Organizer of Xenopus laevis.
Blastomere derivation and domains of gene expression in the Spemann Organizer of Xenopus laevis.
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DOI：
10.1242/dev.121.11.3505
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发表时间：
1995-11
期刊：
影响因子：
4.6
通讯作者：
M. Vodicka;J. Gerhart
中科院分区：
文献类型：
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作者：
M. Vodicka;J. Gerhart
Spemann‘s组织器位于两栖原肠胚背缘区，诱导和区分这种脊椎动物和其他脊椎动物特有的背轴结构。为了追踪非洲爪哇组织者的细胞起源，我们用绿色、红色和蓝色荧光谱系示踪剂标记了32-细胞胚胎四个层次中的三个(A、B和C)的背部卵裂球。标记的无性系在胚泡晚期和原肠胚早期之间发生强烈的植物向外移位，但无性系在其边界处仅轻微混合。典型的早期原肠胚组织者在其动物区由大约10%的A1后代组成，在中心区由70%的B1后代组成，在植物和深部区域由20%的C1后代组成。早期原肠胚组织者组成的可变性是由于早期卵裂面的位置和原肠前期运动的可变性造成的。由于组织者在原肠胚形成过程中内切，形成背轴中胚层，克隆边界被细胞混合大大分散。在克隆中，深层细胞比表层细胞更容易移位和混合。原肠胚晚期背轴中胚层子代分布的差异主要是原肠胚形成过程中细胞混合不同所致。在早期阶段通过分子或胚胎操作扰乱后期发育事件的实验必须考虑这种可变性以及命运图的大多数分布。在原肠胚的早期组织者中，xbra、goosecid、noggin和xNR3基因在动物-植物和浅-深层维度中的表达是不同的。原位杂交和谱系标记确定了背缘区的不同区域。在原肠形成结束时，来自组织者的背轴中胚层细胞已经改变了它们的基因Xbra、Goosecid、noggin和xNR3的表达。在特定的阶段，细胞在胚胎中的位置，而不是它的谱系，可能更重要地决定它将表达哪些基因。
Spemann's Organizer, located in the dorsal marginal zone of the amphibian gastrula, induces and differentiates dorsal axial structures characteristic of this and other vertebrates. To trace the cellular origins of the Xenopus Organizer, we labelled dorsal blastomeres of three of the four tiers (A, B and C) of the 32-cell embryo with green, red and blue fluorescent lineage tracers. A strong vegetalward displacement of labelled clones occurs between the late blastula and early gastrula stages but clones mix only slightly at their borders. The typical early gastrula Organizer is composed of approximately 10% A1 progeny in its animalmost region, 70% B1 progeny in the central region, and 20% C1 progeny in vegetal and deep regions. Variability in the composition of the early gastrula Organizer results from variability in the position of early cleavage planes and in pregastrulation movements. As the Organizer involutes during gastrulation, forming dorsal axial mesoderm, clonal boundaries are greatly dispersed by cell intermixing. Within a clone, deep cells are displaced and intermixed more than superficial cells. Variability in the distribution of progeny in the dorsal axial mesoderm of the late gastrula results mostly from variable intermixing of cells during gastrulation. Experiments to perturb later developmental events by molecular or embryonic manipulations at an early stage must take this variability into account along with the majority distributions of the fate map. Within the early gastrula Organizer, the genes Xbra, goosecoid, noggin and xNR3 are expressed differently in the animal-vegetal and superficial-deep dimensions. In situ hybridization and lineage labelling define distinct regions of the dorsal marginal zone. By the end of gastrulation, dorsal axial mesoderm cells derived from the Organizer have altered their expression of the genes Xbra, goosecoid, noggin and xNR3. At a given stage, a cell's position in the embryo rather than its lineage may be more important in determining which genes it will express.