Photosynthetic algae play a significant role in oceanic carbon capture. However, their performance is constantly challenged by fluctuations in environmental light conditions. While phototaxis is a common strategy to cope with such fluctuations, nonmotile species must adopt alternative mechanisms to avoid light-induced damage. Here, we show that the nonmotile, single-celled marine dinoflagellate Pyrocystis lunula contains a chloroplast network that undergoes strong deformation in response to strong light. By exposing cells to various physiologically relevant light conditions and applying temporal illumination sequences, we find that the light-induced network morphodynamics follows dynamic rules similar to temporal low-pass filtering. We develop a mathematical formalism to model the light-regulated behavior, exposing the relevant timescales of the morphodynamic response. Moreover, confocal microscopy reveals that the unusual reticulated morphology exhibits properties similar to auxetic metamaterials, facilitating the rapid and drastic deformation necessary for the light-avoidance motion, confined by the cell wall. This mechanism reduces the effective chloroplast area under high light conditions, minimizing light absorption and preventing photodamage. Our findings demonstrate that the intricate connection between the chloroplasts topologically complex structure and active dynamics enables the dinoflagellate’s dynamic adaptation to changing light environments, thereby supporting essential life-sustaining processes.

中文翻译：

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单细胞甲藻中光调控的叶绿体形态动力学


光合藻类在海洋碳捕获中起着重要作用。然而，它们的性能不断受到环境光线条件波动的挑战。虽然趋光性是应对这种波动的常见策略，但非运动物种必须采用替代机制来避免光诱导的损伤。在这里，我们表明非运动的单细胞海洋甲藻 Pyrocystis lunula 包含一个叶绿体网络，该网络在强光下会发生强烈变形。通过将细胞暴露于各种生理相关的光照条件并应用时间照明序列，我们发现光诱导的网络形态动力学遵循类似于时间低通滤波的动态规则。我们开发了一种数学形式主义来模拟光调节行为，揭示了形态动力学响应的相关时间尺度。此外，共聚焦显微镜显示，不寻常的网状形态表现出类似于增生超材料的特性，促进了受细胞壁限制的避光运动所需的快速和剧烈变形。这种机制减少了强光条件下的有效叶绿体面积，最大限度地减少了光吸收并防止了光损伤。我们的研究结果表明，叶绿体拓扑复杂结构和主动动力学之间的复杂联系使甲藻能够动态适应不断变化的光环境，从而支持基本的生命维持过程。