Lovely Professional University, Phagwara, Jalandhar, India.
R.N. Singh Memorial Lab, Centre of Advanced study in Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
Protoplasma. 2019 May;256(3):681-691. doi: 10.1007/s00709-018-1328-8. Epub 2018 Nov 19.
The present study was aimed at understanding the effects of heat stress on selected physiological and biochemical parameters of a model cyanobacterium, Anabaena PCC 7120 in addition to amelioration strategy using exogenous Ca. A comparison of the cells exposed to heat stress (0-24 h) in the presence or absence of Ca clearly showed reduction in colony-forming ability and increase in reactive oxygen species (ROS) leading to loss in the viability of cells of Ca-deficient cultures. There was higher level of saturation in membrane lipids of the cells supplemented with Ca along with higher accumulation of proline. Similarly, higher quantum yield (7.8-fold) in Ca-supplemented cultures indicated role of Ca in regulation of photosynthesis. Relative electron transport rate (rETR) decreased in both the sets with the difference in the rate of decrease (slow) in Ca-supplemented cultures. The Ca-supplemented sets also maintained high levels of open reaction centers of PS II in comparison to Ca-deprived cells. Increase in transcripts of both subunits ((rbcL and rbcS) of RubisCO from Ca-supplemented Anabaena cultures pointed out the role of Ca in sustenance of photosynthesis of cells via CO fixation, thus, playing an important role in maintaining metabolic status of the heat-stressed cyanobacterium.
本研究旨在了解热应激对模式蓝藻鱼腥藻 PCC 7120 某些生理生化参数的影响，以及使用外源 Ca 进行缓解的策略。比较在有或没有 Ca 的情况下暴露于热应激（0-24 小时）的细胞，明显显示出集落形成能力降低和活性氧（ROS）增加，导致 Ca 缺乏培养物的细胞活力丧失。用 Ca 补充的细胞的膜脂质饱和度更高，脯氨酸积累更多。同样，Ca 补充培养物中更高的量子产率（7.8 倍）表明 Ca 在光合作用调节中的作用。在两组中，相对电子传递率（rETR）都降低，而 Ca 补充培养物的降低速率（较慢）不同。与 Ca 剥夺细胞相比，Ca 补充组还保持 PS II 开放反应中心的高水平。来自 Ca 补充鱼腥藻培养物的 RubisCO 两个亚基（（rbcL 和 rbcS）的转录物增加表明 Ca 通过 CO 固定在维持细胞光合作用中的作用，从而在维持热应激蓝藻的代谢状态方面发挥重要作用。
