论文标题
植物细胞中的叶绿体在弱光条件下显示出活跃的玻璃行为
Chloroplasts in plant cells show active glassy behavior under low light conditions
论文作者
论文摘要
植物已经开发出复杂的机制来适应不断变化的光条件。除了光学和热情 - 对光线的差异生长以及相对于阳光的昼夜运动 - 叶绿体运动是改变叶片细胞细胞内结构的快速机制。当叶绿体向植物细胞的侧面移动以避免强光,但它们会在低光下积聚并散布成细胞底部的一层,以提高光吸收效率。尽管已经研究了叶绿体的运动已有一个多世纪了,但导致适应自组织结构的光的集体细胞器运动仍然难以捉摸。在这里,我们研究叶绿体在昏暗的光条件下的主动运动,从而导致堆积的准二层层积累。我们观察到类似爆发的重新排列,并表明这些动力学通过跟踪各个叶绿体的胶体系统与玻璃过渡接近的胶体系统。此外,我们提供了一个最小的数学模型,以发现控制叶绿体密集构型稳定性的相关系统参数。我们的研究表明,叶绿体单层中玻璃过渡的元稳定笼具有生理相关性。叶绿体保持在扩散的构型中以增加光吸收,但是当活动增加时,可以轻松地流动以有效地重新安排避免状态的结构。我们的研究开辟了有关动态相变可能在植物细胞对环境线索的细胞内反应中起作用的作用的新问题。
Plants have developed intricate mechanisms to adapt to changing light conditions. Besides photo- and helio- tropism -- the differential growth towards light and the diurnal motion with respect to sunlight -- chloroplast motion acts as a fast mechanism to change the intracellular structure of leaf cells. While chloroplasts move towards the sides of the plant cell to avoid strong light, they accumulate and spread out into a layer on the bottom of the cell at low light to increase the light absorption efficiency. Although the motion of chloroplasts has been studied for over a century, the collective organelle-motion leading to light adapting self-organized structures remains elusive. Here we study the active motion of chloroplasts under dim light conditions, leading to an accumulation in a densely packed quasi-2D layer. We observe burst-like re-arrangements and show that these dynamics resemble colloidal systems close to the glass transition by tracking individual chloroplasts. Furthermore, we provide a minimal mathematical model to uncover relevant system parameters controlling the stability of the dense configuration of chloroplasts. Our study suggests that the meta-stable caging close to the glass-transition in the chloroplast mono-layer serves a physiological relevance. Chloroplasts remain in a spread-out configuration to increase the light uptake, but can easily fluidize when the activity is increased to efficiently re-arrange the structure towards an avoidance state. Our research opens new questions about the role that dynamical phase transitions could play in self-organized intracellular responses of plant cells towards environmental cues.