BACKGROUND A feedforward loop (FFL) is commonly observed in several biological networks. The FFL network motif has been mostly studied with respect to variation of the input signal in time, with only a few studies of FFL activity in a spatially distributed system such as morphogen-mediated tissue patterning. However, most morphogen gradients also evolve in time. RESULTS We studied the spatiotemporal behavior of a coherent FFL in two contexts: (a) a generic, oscillating morphogen gradient and (b) the dorsal-ventral patterning of the early Drosophila embryo by a gradient of the NF-κB homolog dorsal with its early target Twist. In both models, we found features in the dynamics of the intermediate node-phase difference and noise filtering-that were largely independent of the parameterization of the models, and thus were functions of the structure of the FFL itself. In the dorsal gradient model, we also found that proper target gene expression was not possible without including the effect of maternal pioneer factor Zelda. CONCLUSIONS An FFL buffers fluctuation to changes in the morphogen signal ensuring stable gene expression boundaries.

中文翻译：

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使用前馈回路对基因表达边界进行时空控制。

背景技术前馈回路（FFL）通常在几种生物网络中观察到。FFL网络基序主要针对输入信号随时间的变化进行了研究，而在空间分布系统（例如形态发生子介导的组织构图）中对FFL活性的研究很少。但是，大多数形态发生素梯度也会随时间变化。结果我们在两种情况下研究了相干FFL的时空行为：（a）通用的振荡形态发生子梯度；（b）果蝇早期胚胎通过背侧NF-κB同源梯度与早期背侧梯度的背腹模式目标扭曲。在这两个模型中，我们发现中间节点相差和噪声滤波的动力学特性在很大程度上与模型的参数化无关，因此是FFL本身结构的功能。在背梯度模型中，我们还发现，如果不考虑母体先驱因子塞尔达的影响，则不可能正确表达靶基因。结论FFL缓冲了形态发生信号变化的波动，确保了稳定的基因表达边界。