DROSOPHILA EYE DEVELOPMENT - NOTCH AND DELTA AMPLIFY A NEUROGENIC PATTERN CONFERRED ON THE MORPHOGENETIC FURROW BY SCABROUS
DROSOPHILA EYE DEVELOPMENT - NOTCH AND DELTA AMPLIFY A NEUROGENIC PATTERN CONFERRED ON THE MORPHOGENETIC FURROW BY SCABROUS
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DOI：
10.1016/0925-4773(94)00314-d
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发表时间：
1995-02-01
影响因子：
2.6
通讯作者：
ZITRON, AE
中科院分区：
文献类型：
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作者：
BAKER, NE;ZITRON, AE
Notch和Delta的粗糙等位基因和条件等位基因的功能缺失突变影响形态发生沟发育的模式。通过研究R8细胞（第一个感光神经元亚型）的分化，我们发现所有沟细胞都经历了R8能态阶段。Notch和scabrous的功能是这些细胞获得其他细胞命运的必要条件。粗糙基因赋予形成沟的规则模式，限制R8分化为交替的细胞群。Notch和Delta功能将R8的命运限制在每组中的单个细胞上。在没有粗糙基因功能的情况下，Notch和Delta对整个形态发生沟的作用导致由单个R8细胞无序排列产生的无组织的小眼细胞模式。粗糙突变表型的各个方面也表明，在从胜任簇中选择单个R8细胞方面起次要作用。我们发现粗糙表达先于识别原体细胞的形态发生沟细胞的顶端轮廓的变化，也先于Notch和Delta表达水平的变化。海洋基因表达的起始模式取决于海洋基因的功能，这表明形态发生沟的模式取决于后柱的模式。我们的研究结果表明，在眼内，Notch和Delta放大和细化了粗糙岩产生的形态发生景观。其他组织和生物体中的细胞决定也可能在两步过程中形成，其中由一种蛋白质决定的初始不均匀性为随后的发展提供了背景。
Loss of function mutations of scabrous and conditional alleles of Notch and Delta affect the pattern of morphogenetic furrow development. By studying differentiation of R8 cells, the first photoreceptor neuron subtype to differentiate, we show that all furrow cells pass through an R8-competent stage. Function of Notch and scabrous is necessary if most of these cells are to attain other cell fates. The scabrous gene confers a regular pattern on the morphogenetic furrow, restricting R8 differentiation to alternating groups of cells. Notch and Delta function to restrict the R8 fate to a single cell in each group. Without scabrous gene function, action of Notch and Delta on the entire morphogenetic furrow results in a disorganised pattern of ommatidia arising from a disorganised array of single R8 cells. Aspects of the scabrous mutant phenotype also suggest a secondary role in selecting a single R8 cell from competent clusters. We show that scabrous expression preceeds changes in the apical profiles of morphogenetic furrow cells that identify ommatidial precursor cells, and also preceeds changes in levels of Notch and Delta expression. The pattern of initiation of sea expression depends on sea gene function, indicating that patterning of the morphogenetic furrow depends on the pattern of posterior columns. Our results suggest that in the eye, Notch and Delta amplify and refine a morphogenetic landscape generated by scabrous. Cell determination in other tissues and organisms might also be molded in a two-step process where initial inhomogeneities determined by one protein provide a context for subsequent development.