Physiological and Biochemical Response of the Photosynthetic Apparatus of Two Marine Diatoms to Fe Stress
Physiological and Biochemical Response of the Photosynthetic Apparatus of Two Marine Diatoms to Fe Stress
复制标题
两种海洋硅藻光合机构对铁胁迫的生理生化响应
DOI：
10.1104/pp.114.2.615
复制
发表时间：
1997
影响因子：
1.4
通讯作者：
J. LaRoche
中科院分区：
文献类型：
--
作者：
R. McKay;R. Geider;J. LaRoche
黄还蛋白是一种小的电子转移蛋白，能够在缺铁时期替代铁还蛋白。在评估黄毒素作为铁限制浮游植物生长的诊断指标的适宜性时，我们检测了它在两种海洋硅藻中的表达，这些硅藻是用微量金属缓冲介质培养的。威氏褐指藻和三角褐指藻在乙二胺四乙酸缓冲马尾藻海水中培养，海水中添加了10~1000 nm的铁。每种硅藻的微量金属缓冲培养物在整个铁添加范围内都保持了较高的生长速度。类似地，叶绿素/细胞数和光系统II可变/最大荧光比的下降可以忽略不计(三角褐指藻)到中等程度(三角藻；每细胞叶绿素下降54%，可变/最大荧光下降22%)。此外，在整个添加范围内，仅观察到光合作用参数的微小变化。相反，在低铁培养中，黄毒素的表达水平很高。尽管黄还蛋白的表达与培养液中的铁含量呈负相关，但它的表达似乎与所检测的任何细胞生理指标无关。黄毒素似乎被表达为对铁胁迫的早期反应，其积累不必与铁对这些硅藻的生长速度施加的限制密切相关。
Flavodoxin is a small electron-transfer protein capable of replacing ferredoxin during periods of Fe deficiency. When evaluating the suitability of flavodoxin as a diagnostic indicator for Fe limitation of phytoplankton growth, we examined its expression in two marine diatoms we cultured using trace-metal-buffered medium. Thalassio-sira weissflogii and Phaeodactylum tricornutum were cultured in ethylenediaminetetraacetic acid-buffered Sargasso Sea water containing from 10 to 1000 nM added Fe. Trace-metal-buffered cultures of each diatom maintained high growth rates across the entire range of Fe additions. Similarly, declines in chlorophyll/cell and in the ratio of photosystem II variable-to-maximum fluorescence were negligible (P. tricornutum) to moderate (T. weissflogii; 54% decline in chlorophyll/cell and 22% decrease in variable-to-maximum fluorescence). Moreover, only minor variations in photosynthetic parameters were observed across the range of additions. In contrast, flavodoxin was expressed to high levels in low-Fe cultures. Despite the inverse relationship between flavodoxin expression and Fe content of the medium, its expression was seemingly independent of any of the indicators of cell physiology that were assayed. It appears that flavodoxin is expressed as an early-stage response to Fe stress and that its accumulation need not be intimately connected to limitations imposed by Fe on the growth rate of these diatoms.