Iron requirements of the pennate diatom Pseudo-nitzschia:: Comparison of oceanic (high-nitrate, low-chlorophyll waters) and coastal species
Iron requirements of the pennate diatom Pseudo-nitzschia:: Comparison of oceanic (high-nitrate, low-chlorophyll waters) and coastal species
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DOI：
10.4319/lo.2006.51.5.2092
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发表时间：
2006-09-01
影响因子：
4.5
通讯作者：
Harrison, Paul J.
中科院分区：
文献类型：
--
作者：
Marchetti, Adrian;Maldonado, Maria T.;Harrison, Paul J.
我们量化并比较了几种新分离自亚北极太平洋东北部高硝酸盐、低叶绿素水域的海洋伪硝子藻（Pseudonitzschia spp）与沿海伪硝子藻（Pseudonitzschia spp）和海洋中心硅藻（Thalassiosira oceanica）在不同铁浓度下的生理参数和铁需要量。在富铁条件下，6株伪尼茨氏菌的铁（Fe）：碳(C)比值在157 μ mol Fe mol C-1 ~ 248 μ mol Fe mol C-1之间，在海洋和沿海地区无明显差异。在低铁条件下，所有拟nitzschia属植物的光合效率均显著降低，但不同物种的特定生长率降低程度不同。当铁限制时，所有海洋伪尼氏菌的Fe: C比值均显著降低，最低值为2.8 μ mol Fe mol C-1 ~ 3.7 μ mol Fe mol C-1。与较快的生长速度相结合，在海洋分离的伪尼茨奇菌中，较低的铁碳比导致其铁利用效率显著高于其沿海同系物和大洋菌。富铁（Fe-Q（高））和限铁（Fe-Q（低））指标之间的较大范围表明，相对于文献中报道的在相似铁浓度下生长的其他硅藻，海洋伪尼齐亚藻在铁含量方面具有广泛的可塑性；海洋种Fe-Qhigh: Fe-Q（low）比值为46 ~ 67，沿海拟尼奇亚种Fe-Qhigh: Fe-Q（low）比值为16 ~ 43。我们认为，海洋伪nitzschia物种对铁富集事件表现出广泛的生长反应的能力，部分可能是由于它们在铁浓度高时积累和潜在储存大量细胞内铁的非凡能力，但在外部铁浓度耗尽后，它们却大大减少了铁的需求，以维持快速生长。
We quantified and compared physiological parameters and iron requirements of several oceanic Pseudonitzschia spp., newly isolated from the high-nitrate, low-chlorophyll waters of the northeast subarctic Pacific, with coastal Pseudo-nitzschia spp. and the oceanic centric diatom Thalassiosira oceanica at a range of iron concentrations. In iron-replete conditions, the iron (Fe): carbon (C) ratios in the six Pseudo-nitzschia isolates ranged from 157 mu mol Fe mol C-1 to 248 mu mol Fe mol C-1, with no apparent differences between oceanic and coastal isolates. In low iron conditions, all Pseudo-nitzschia spp. exhibited marked reductions in photosynthetic efficiency, whereas the extent of the reductions in specific growth rates varied among species. When iron-limited, the Fe: C ratios decreased significantly in all oceanic Pseudo-nitzschia species, with the lowest ratios ranging from 2.8 mu mol Fe mol C-1 to 3.7 mu mol Fe mol C-1. Combined with faster growth rates, lower Fe: C ratios in oceanic isolates of Pseudo-nitzschia resulted in significantly higher iron-use efficiencies relative to their coastal congeners and T oceanica. The wide range between iron-replete (Fe-Q(high)) and iron-limited (Fe-Q(low)) quotas indicates that oceanic Pseudo-nitzschia spp. have an extensive plasticity in iron contents relative to other diatoms grown at similar iron concentrations reported in the literature; the Fe-Qhigh: Fe-Q(low) ratios for oceanic species were 46 to 67, whereas for coastal Pseudo-nitzschia species they were 16 and 43. We suggest that the ability of oceanic Pseudo-nitzschia species to exhibit an extensive growth response to iron enrichment events may, in part, be a result of their extraordinary capacity to accumulate and potentially store large amounts of intracellular iron when iron concentrations are high, yet substantially reduce their iron requirements to sustain fast growth rates well after external iron concentrations are depleted.