A short version of the ammonium-nitrate interaction model

The performance of the complex ammonium-nitrate interactionmodel (ANIM) of Flynn et al. (Philos. Trans. R. Soc., 352, 1997)is compared with that of a simplified version (SHANIM) in whichthe internal pools of inorganic nitrogen (N) and the enzymesof nitrate-nitrite reduction and glutamine synthetase are absent.Although SHANIM is incapable of simulating cell size-linkedprocesses such as the accumulation of inorganic N and the uncouplingof inorganic N transport from assimilation, it offers a goodcompromise for those needing a simplified modelling solution.The general close agreement between ANIM and SHANIM simulations(usually differing in the details of nutrient transport by phasingof a few hours even in a light-dark cycle) is due to the retentionof two major features of ANIM, namely nutrient history-linkedtransport rates for nitrate and ammonium and regulation of transportby an organic product of N assimilation (glutamine).