A storage-based model of heterocyst commitment and patterning in cyanobacteria

作者：Brown Aidan I; Rutenberg Andrew D^*

来源：Physical Biology, 2014, 11(1): 016001.

DOI：10.1088/1478-3975/11/1/016001

• cyanobacterial filament
• heterocyst commitment
• developmental pattern
• lateral inhibition
• computational model

When deprived of fixed nitrogen (fN), certain filamentous cyanobacteria differentiate nitrogen-fixing heterocysts. There is a large and dynamic fraction of stored fN in cyanobacterial cells, but its role in directing heterocyst commitment has not been identified. We present an integrated computational model of fN transport, cellular growth, and heterocyst commitment for filamentous cyanobacteria. By including fN storage proportional to cell length, but without any explicit cell-cycle effect, we are able to recover a broad and late range of heterocyst commitment times and we observe a strong indirect cell-cycle effect. We propose that fN storage is an important component of heterocyst commitment and patterning in filamentous cyanobacteria. The model allows us to explore both initial and steady-state heterocyst patterns. The developmental model is hierarchical after initial commitment: our only source of stochasticity is observed growth rate variability. Explicit lateral inhibition allows us to examine Delta patS, Delta hetN, and Delta patN phenotypes. We find that Delta patS leads to adjacent heterocysts of the same generation, while Delta hetN leads to adjacent heterocysts only of different generations. With a shortened inhibition range, heterocyst spacing distributions are similar to those in experimental Delta patN systems. Step-down to non-zero external fN concentrations is also investigated.

• 出版日期2014-2