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Juggling Lightning: How Chlorella ohadii handles extreme energy inputs without damage
Photosynthesis Research ( IF 3.7 ) Pub Date : 2021-01-02 , DOI: 10.1007/s11120-020-00809-9
Isaac Kedem 1 , Yuval Milrad 2 , Aaron Kaplan 1 , Iftach Yacoby 2
Affiliation  

The green alga Chlorella ohadii was isolated from a desert biological soil crust, one of the harshest environments on Earth. When grown under optimal laboratory settings it shows the fastest growth rate ever reported for a photosynthetic eukaryote and a complete resistance to photodamage even under unnaturally high light intensities. Here we examined the energy distribution along the photosynthetic pathway under four light and carbon regimes. This was performed using various methodologies such as membrane inlet mass spectrometer with stable O2 isotopes, variable fluorescence, electrochromic shift and fluorescence assessment of NADPH level, as well as the use of specific inhibitors. We show that the preceding illumination and CO2 level during growth strongly affect the energy dissipation strategies employed by the cell. For example, plastid terminal oxidase (PTOX) plays an important role in energy dissipation, particularly in high light- and low-CO2-grown cells. Of particular note is the reliance on PSII cyclic electron flow as an effective and flexible dissipation mechanism in all conditions tested. The energy management observed here may be unique to C. ohadii, as it is the only known organism to cope with such conditions. However, the strategies demonstrated may provide an insight into the processes necessary for photosynthesis under high-light conditions.



中文翻译:

杂耍闪电:Ohadii 小球藻如何处理极端能量输入而不会造成损坏

绿藻Chlorella ohadii是从沙漠生物土壤地壳中分离出来的,这是地球上最恶劣的环境之一。当在最佳实验室环境下生长时,它显示出光合真核生物有史以来最快的生长速度,并且即使在不自然的高光强度下也能完全抵抗光损伤。在这里,我们研究了在四种光和碳机制下沿着光合作用途径的能量分布。这是使用各种方法进行的,例如具有稳定 O 2同位素的膜入口质谱仪、可变荧光、电致变色位移和 NADPH 水平的荧光评估,以及使用特定抑制剂。我们表明,前面的照明和 CO 2生长期间的水平强烈影响细胞采用的能量耗散策略。例如,质体末端氧化酶 (PTOX) 在能量耗散中起着重要作用,特别是在高光和低 CO 2生长的细胞中。特别值得注意的是,在所有测试条件下,都依赖 PSII 循环电子流作为一种有效且灵活的耗散机制。这里观察到的能量管理可能是C. ohadii所独有的因为它是唯一已知的能够应对这种情况的生物。然而,所展示的策略可能有助于深入了解强光条件下光合作用所需的过程。

更新日期:2021-01-03
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