Allard Jun F, Hill Alison L, Rutenberg Andrew D
Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1Z9.
Dev Biol. 2007 Dec 1;312(1):427-34. doi: 10.1016/j.ydbio.2007.09.045. Epub 2007 Sep 29.
We have quantitatively modeled heterocyst differentiation after fixed nitrogen step-down in the filamentous cyanobacterium Anabaena sp. PCC 7120 without lateral inhibition due to the patterning proteins PatS or HetN. We use cell growth and division together with fixed-nitrogen dynamics and allow heterocysts to differentiate upon the local exhaustion of available fixed nitrogen. Slow transport of fixed nitrogen along a shared periplasmic space allows for fast growing cells to differentiate ahead of their neighbors. Cell-to-cell variability in growth rate determines the initial heterocyst pattern. Early release of fixed nitrogen from committed heterocysts allows a significant fraction of vegetative cells to be retained at later times. We recover the experimental heterocyst spacing distributions and cluster size distributions of Khudyakov and Golden [Khudyakov, I.Y., Golden, J.W., 2004. Different functions of HetR, a master regulator of heterocyst differentiation in Anabaena sp PCC 7120, can be separated by mutation. Proc. Natl. Acad. Sci. U. S. A. 101, 16040-16045].
我们对丝状蓝细菌鱼腥藻7120在固定氮源减少后异形胞分化进行了定量建模，该过程不存在因模式形成蛋白PatS或HetN导致的侧向抑制。我们将细胞生长与分裂以及固定氮动态变化相结合，并允许异形胞在可用固定氮局部耗尽时分化。固定氮沿共享周质空间的缓慢运输使得快速生长的细胞能够比其相邻细胞更早分化。细胞间生长速率的差异决定了初始异形胞模式。已分化异形胞中固定氮的早期释放使得相当一部分营养细胞在后期得以保留。我们重现了Khudyakov和Golden [Khudyakov, I.Y., Golden, J.W., 2004. Different functions of HetR, a master regulator of heterocyst differentiation in Anabaena sp PCC 7120, can be separated by mutation. Proc. Natl. Acad. Sci. U. S. A. 101, 16040 - 16045]的实验异形胞间距分布和簇大小分布。
