(B,C) Voltage dependencies of the (B) H/P and (C) H/C cotransporters were approximated by first-order Taylor approximation. (A) Voltage dependence of the background conductance I background = I BG = I BGmax × (1 − exp)/(1 + exp) here V 0 = −100 mV (black curves) or V 0 = −50 mV (gray curve) I BGmax = 20 fA/µm 2 (solid lines), I BGmax = 10 fA/µm 2 (dotted line). | Mathematical description of transporter activities. (B) Screenshot of the implementation of the three compartment model in VCell. The qualitative conclusions would be identical to the considered P/C-exchange system.
In order to include the exchange of nitrogen sources, the network could be enlarged by NH4+-channels and electrogenic H+/NO3-, H+/amino acid or H+/peptide co-transporters (Smith and Smith, 2011 Casieri et al., 2013). The background conductance gathers the H+-ATPase and other potential ionic conductances.
Transport of sugar or phosphate was mediated by H+/sugar (H/C) and H+/phosphate (H/P) cotransporters. The pH values were kept constant to pHcyt = 7.0 and pHapo = 6.0 to reflect the proton-buffer capacities (see also Discussion for the flexibility of these values). Note that different cytoplasms/apoplasm values do not qualitatively change the obtained results. (A) The exchange zone was modeled as a three-compartment system with the 100 nm thick interfacial apoplast between plant and fungus and 50-fold larger cytoplasmic volumes. As a first step towards this goal, we included SWEET sugar transporters in the model and show that their co-occurrence with proton-coupled sugar transporters results in a futile carbon cycle at the plant plasma membrane proposing that two different pathways for the same substrate should not be active at the same time.Ī minimal transporter network for nutrient exchange in arbuscular mycorrhizal symbiosis. The minimal model presented here may serve as benchmark to evaluate in future the performance of more complex models of AM nutrient exchange.
This computational cell biology study allows drawing far reaching hypotheses about the mechanism and the regulation of nutrient exchange and proposes that the ‘cooperation’ between plant and fungus can be in fact the result of a competition between both for the same resources in the tiny periarbuscular space. By applying basic principles of microeconomics, we link the biophysics of transmembrane nutrient transport with the ecology of organismic interactions and straightforwardly explain macroscopic scenarios of the relations between plant and AM fungus. We show that this minimal network is sufficient to describe accurately and realistically the nutrient trade system. Here, we used computational cell biology to simulate the dynamics of a network of proton pumps and proton-coupled transporters that are upregulated during AM formation. Until now it is not clear how this nutrient exchange system works. Gallery Click here to view the image gallery for Red Revert.In arbuscular mycorrhizal (AM) symbiosis, fungi and plants exchange nutrients (sugars and phosphate, for instance) for reciprocal benefit. The Red Revert acts similar to the Miraculous Ladybug superpower, with the only difference is that when used to reverse the damage, it shoots a circular wave that expands at fast speeds reversing the damage more quicker.The Red Miraculous user throws up their fist to shoot a blast of Red energy from the top and utilize it to cause a circular wave of Red Aura to speed and reverse the damage by expanding the circle across Paris, usually reversing any type of damage and erasing the memory of the akumatized villain having no memory of what happened to them during their fight with the Red Miraculous owner. Once the akumatized villain has been defeated, the Red Miraculous holder must first de-evilize them by capturing their akuma, using their Red Aura magic to reverse them into a butterfly, then they can throw up their fist sending a energy wave upwards fixing and reversing the damage, including erasing the akumatized villain's memory.
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