基因网络前馈环路中的涨落共振

应用化学主方程和线性涨落近似方法，重点研究了前馈环路（FFL）对外界输入弱信号的响应，特别考察了它的涨落共振现象．研究发现Z基因的FR行为很大程度上依赖于FFL的协同性：协同FFL中Z的FR曲线呈明显的单峰，而非协同FFL中该曲线出现明显双峰．由于振荡信号常常在实际应用中用来探测网络的调控结构，因此可以利用涨落共振曲线的定性差别来区分FFL网络的性能．

Fluctuation Resonance of Feed Forward Loops in Gene Regulatory Networks

The feed forward loop （FFL）, wherein a gene X can regulate target gene Z alone or cooperatively with gene Y, is one of the most important motifs in gene regulatory networks. Gene expression often involves a small number of reactant molecules and thus internal molecular fluctuation is considerable. Here we studied how an FFL responds to small external signal inputs at gene X, with particular attention paid to the fluctuation resonance （FR） phenomenon of gene Z. We found that for all coherent FFLs, where the sign of the direct regulation path from X to Z is the same as the overall sign of the indirect path via Y, the FR shows a regular single peak, while for incoherent FFLs, the FR exhibits distinct bimodal shapes. The results indicate that one could use small external signals to help identify the regulatory structure of an unknown FFL in complex gene networks.