The elemental stoichiometry and composition of an iron‐limited diatom
The elemental stoichiometry and composition of an iron‐limited diatom
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DOI：
10.4319/lo.2005.50.4.1159
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发表时间：
2005-07
影响因子：
4.5
通讯作者：
N. M. Price
中科院分区：
文献类型：
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作者：
N. M. Price
我们在一系列铁限制条件下以硝酸盐或铵作为N源将海链藻培养至稳定状态。硝酸盐依赖性细胞具有更快的铁吸收速率，含有显着更高的细胞内铁配额，并且比在铁最受限制时用NH 4+培养的细胞生长得更快。在此条件下，碳（C）：叶绿素a比值和每个叶绿素a的最小荧光产量增加，但氮源对这两个参数没有影响。即使在T. weissflocculant以其最大速率（μmax）的25%生长。硝酸盐中的C：N比高于铵生长的细胞，并且在所有Fe水平下都是恒定的。蛋白质不依赖于Fe和N，氨基酸在使用NO3−的细胞中最低。T.当Fe成为生长的最大限制时，Weissflocker（mol P L−1细胞体积）增加了1.5倍，导致N：P和C：P比值显著下降。Fe的元素化学计量限制了T.因此，与营养物充足条件下的97 C：14 N：4.7 Si：1 P：0.029 Fe相比，weissfloctane（0.25µmax）为70 C：10 N：5.9 Si：1 P：0.00074 Fe（摩尔）。NO3-：PO 43-的吸收速率比显示出与细胞N：P配额相同的对Fe的依赖性，随着[Fe]的降低而降低。铁的限制影响了这种海洋硅藻的元素组成，并会改变同化率的C，N，和P在高硝酸盐，低叶绿素地区的海洋。
We grew Thalassiosira weissflogii to steady state over a range of Fe‐limiting conditions with nitrate or ammonium as the N source. Nitrate‐dependent cells had faster Fe‐uptake rates, contained significantly higher intracellular Fe quotas, and grew faster than cells cultivated with NH4+ when Fe was most limiting. Under these conditions, carbon (C) : chlorophyll a ratios and the minimum fluorescence yield per chlorophyll a increased, but N source had no effect on either parameter. The ratio of variable to maximum fluorescence (Fv Fm−1) declined little with Fe limitation m even when T. weissflogii was grown at 25% of its maximum rate (µmax). C:N ratios were higher in nitrate than in ammonium‐grown cells and were constant at all Fe levels. Protein was independent of Fe and N, and amino acids were lowest in cells using NO3−. The P content of T. weissflogii (mol P L−1 cell volume) increased by 1.5 times as Fe became most limiting to growth, causing N: P and C: P ratios to decline significantly. The elemental stoichiometry for Fe‐limited new production of T. weissflogii (0.25µmax) was thus 70C : 10N : 5.9Si : 1P : 0.00074Fe (by mols) compared with 97C : 14N : 4.7Si : 1P : 0.029Fe for nutrient‐replete conditions. Uptake rate ratios of NO3− : PO43− showed the same dependence on Fe as the cellular N: P quotas, decreasing as [Fe] decreased. Iron limitation influenced the elemental composition of this marine diatom and will alter the assimilation ratios of C, N, and P in the high nitrate, low chlorophyll regions of the sea.