Interactions between iron, light, ammonium, and nitrate: Insights from the construction of a dynamic model of algal physiology
Interactions between iron, light, ammonium, and nitrate: Insights from the construction of a dynamic model of algal physiology
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DOI：
10.1046/j.1529-8817.1999.3561171.x
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发表时间：
1999-12-01
影响因子：
2.9
通讯作者：
Hipkin, CR
中科院分区：
文献类型：
--
作者：
Flynn, KJ;Hipkin, CR
描述了一个动态机械数学模型（FeLANIM），能够模拟浮游植物中铁，光，铵和硝酸盐之间的主要记录的相互作用。在模型中有不同的点，物种或群体特异性（例如真核生物与原核生物）的细节可能会改变。模型中考虑的细胞含铁过程是光合作用、氧化磷酸化和硝酸盐同化;光合系统和硝酸盐和亚硝酸盐还原酶（NNiR）的合成是剩余铁配额（即总铁配额减去功能组分中的铁）的函数。模型模拟运行使用一系列不同的生理参数为铁依赖的过程和对比铵-硝酸盐相互作用的情况。模型输出表明了以下相互作用。由于铁在光合系统中的比例随光照而变化，因此不可能有单一的硝酸盐同化铁成本。铁胁迫可以影响铵和硝酸盐同化（f-比率）之间的关系，在较低浓度的铵硝酸盐利用更迅速的抑郁症。然而，根据高N：C下硝酸盐同化的抑制程度，这样的结果可能并不普遍，需要进一步的实验研究来澄清这个问题。补铁后24-48 h内，生长速度迅速恢复，并伴随着chi a含量的增加。因此，仅根据色素的增加来估计铁施肥实验中的增产可能被夸大了。铁再喂养的NNiR活性的刺激似乎是间接的，通过增强光合作用，而不是缓解硝酸盐胁迫。在高光照下Fe再补食过程中，硝酸盐营养的细胞比铵营养的细胞增加更多的N养分运输。改变氮源供应给模拟铁胁迫的细胞从硝酸盐到铵的结果在快速增加的生长速度和铁的利用效率与色素含量的增加，作为NNiR含量下降。当硝酸盐取代铵，驯化是缓慢的，因为重定向的铁以前在光系统NNiR。通过揭示可能在确定物种之间竞争优势方面最重要的生理学要素，该模型的操作可能被证明是有用的，可以作为新研究的指标。
A dynamic mechanistic mathematical model (FeLANIM) is described, capable of simulating the major documented interactions between iron, light, ammonium, and nitrate in phytoplankton. There are various points in the model where species- or group-specific (e.g. eukaryote vs. prokaryote) details may be altered. Cellular Fe-containing processes accounted for in the model are photosynthesis, oxidative phosphorylation, and nitrate assimilation; synthesis of photosystems and nitrate and nitrite reductase (NNiR) are functions of the surplus Fe quota (i.e. total Fe quota minus Fe in functional components). Model simulations were run using a range of different physiological parameters for Fe-dependent processes and contrasting ammonium-nitrate interaction scenarios. Model output indicated the following interactions. Because the proportion of Fe in photosystems varies with irradiance, it is not possible to have a single Fe cost for nitrate assimilation. Fe stress can affect the relationship between ammonium and nitrate assimilations (the f-ratio), with a more rapid depression of nitrate use at lower concentrations of ammonium. However, depending on the degree of the repression of nitrate assimilation at high N:C, such a result may not be universal, and further experimental studies are required to clarify this issue. Fe refeeding results in a rapid recovery of growth rate accompanied by a proportionately greater increase in the amount of chi a within 24-48 h. Estimates of enhanced production in iron fertilization experiments based only on increases in pigment may thus be exaggerated. Stimulation of NNiR activity on Fe refeeding appears indirect, through enhancement of photosynthesis rather than relief of nitrate stress. During Fe refeeding at high light, N nutrient transport increases proportionately more in nitrate-fed cells than in ammonium-fed cells. Changing the N source supplied to simulated Fe-stressed cells from nitrate to ammonium results in a rapid increase in growth rate and iron use efficiency with an increase in pigment content as NNiR content declines. When nitrate replaces ammonium, acclimation is slower because of the redirection of Fe formerly associated in photosystems to NNiR. Manipulation of the model may prove useful as an indicator for new research, by revealing elements of physiology that may be most significant in determining competitive advantage between species.