小球藻中钙信号转导和中性脂合成密切相关

Ca2+作为植物细胞中最重要的第二信使，参与了植物许多逆境过程的信号转导。在非生物逆境条件下，植物细胞中的钙离子在时间、空间及浓度上会出现特异性变化，即诱发产生钙信号。钙信号再通过其下游的钙结合蛋白进行感受和转导，进而在细胞内引发一系列的生物化学反应以适应或抵制各种逆境的胁迫。N限制作为其中一种非生物胁迫被认为是影响植物生长和代谢的重要因素，藻类植物在受到氮素胁迫时会合成一定的淀粉和脂质对胁迫进行响应。作者认为这种适应胁迫的代谢过程与钙离子的信号转导过程相关。

本研究中，作者选取绿藻(Chlorella sp. C2)作为实验材料，设置BG11溶液对照组和去除NaNO3的BG11溶液的处理组，利用NMT结合其他技术探讨藻类植物在受到N胁迫时Ca2+在时间、空间及浓度上的变化及离子所涉及的代谢过程调控。结果表明，绿藻的钙离子在对照组中呈外流状态，在受到胁迫的初期阶段(0-2天)，N素的缺失显著的降低了钙离子的流速，在后半阶段(2-8天)，钙离子的流速持续降低最终呈内流状态，且处理组和对照组差异显著(如下图)。

图注： 上图为实时获取的样品检测图，下图为绿藻在受到N胁迫后，不同时间段的Ca2+流速变化。正值表示外流，负值表示内流。

NMT作为一种非损伤实时测定活体样品的技术，与膜片钳技术和荧光成像技术相比，能解决上述技术无法揭示离子在时间、空间变化的缺陷。在说明信号转导过程中离子的流速变化的问题上，NMT技术更是一项不可缺少的技术。

原文摘要：

The fluxes of H2O2 and O2 can be used to evaluate seed germination and vigor ofCaragana korshinskii

Jiaguo Li, Yu Wang, Hugh W. Pritchard, Xiaofeng Wang

Seed deterioration is detrimental to plant germplasm conservation, and predicting seed germination and vigor with reliability and sensitivity means is urgently needed for practical problems. We investigated the link between hydrogen peroxide (H2O2) flux, oxygen influx and seed vigor ofCaragana korshinskii by the non-invasive micro-test technique (NMT). Some related physiological and biochemical changes in seeds were also determined to further explain the changes in the molecular fluxes. The results showed that there was a good linear relationship between germination and H2O2 flux, and that O2 influx was more suitable for assessing seed vigor. H2O2 flux changed relatively little initially, mainly affected by antioxidants (APX, CAT and GSH) and H2O2 content; afterward, the efflux increased more and more rapidly due to high membrane permeability. With the damage of mitochondrial respiration and membrane integrity, O2 influx was gradually reduced. We propose that monitoring H2O2 and O2 fluxes by NMT may be a reliable and sensitive method to evaluate seed germination and vigor.

作者：旭月