The segment polarity network is a robust developmental module
The segment polarity network is a robust developmental module
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DOI：
10.1038/35018085
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发表时间：
2000-07-13
期刊：
影响因子：
64.8
通讯作者：
Odell, GM
中科院分区：
文献类型：
--
作者：
von Dassow, G;Meir, E;Odell, GM
所有昆虫都有同源片段，但不同昆虫目的片段规格有很大不同。在果蝇中，母体形态基因控制着GAP基因的模式化激活，GAP基因编码的转录调节因子塑造了配对规则基因的模式化表达。这种图案化的级联发生在细胞化之前。配对规则基因产物随后‘印记’带有重复模式的片段极性基因，从而定义原始片段。在昆虫群体中，这种机制必须得到很大的修改，因为在昆虫群体中，许多节段是在细胞化之后才出现的。例如，在甲虫和寄生蜂中，配对规则同源基因在分割过程中以与角色一致的模式表达，但这些模式出现在细胞场中(2-4)。相反，虽然在蝗虫中配对规则同系物可能不能控制分段(5，6)，但一些片段极性基因及其相互作用是保守的(3，7-10)。也许分段是模块化的，每个模块自主地表达一种特有的内在行为，以响应瞬时刺激。如果是这样的话，进化可以重新安排模块的输入，而不会改变它们的内在行为。在这里，我们建议，使用计算机模拟，果蝇片段的极性基因构成了这样一个模块，并且这个模块对控制其行为的动力学常数的变化具有抵抗力。
All insects possess homologous segments, but segment specification differs radically among insect orders. In Drosophila, maternal morphogens control the patterned activation of gap genes, which encode transcriptional regulators that shape the patterned expression of pair-rule genes. This patterning cascade takes place before cellularization. Pair-rule gene products subsequently 'imprint' segment polarity genes with reiterated patterns, thus defining the primordial segments. This mechanism must be greatly modified in insect groups in which many segments emerge only after cellularization(1). In beetles,and parasitic wasps, for instance, pair-rule homologues are expressed in patterns consistent with roles during segmentation, but these patterns emerge within cellular fields(2-4). In contrast, although in locusts pair-rule homologues may not control segmentation(5,6), some segment polarity genes and their interactions are conserved(3,7-10). Perhaps segmentation is modular, with each module autonomously expressing a characteristic intrinsic behaviour in response to transient stimuli. If so, evolution could rearrange inputs to modules without changing their intrinsic behaviours. Here we suggest, using computer simulations, that the Drosophila segment polarity genes constitute such a module, and that this module is resistant to variations in the kinetic constants that govern its behaviour.