Coping with Darkness: The Physiological Responses of Marine Microalgae to Aphotic Conditions and their Ecological Implications

本研究旨在测试延长黑暗对底栖和浮游硅藻光合能力的影响。浮游植物和底栖藻类周围的河口光场的拉格朗日模型表明，暴露在黑暗中2 - 5天是很常见的。初步证据表明，在几天的黑暗后，物种的生理能力有相当大的差异，但造成这些差异的因素尚不清楚。据推测，在长时间的黑暗中，代谢和生理变化会改变光合机构和随后细胞对光的反应能力。研究主要集中在光合调节的两个时间尺度上。延长的时间尺度将通过测量光合作用成分的变化来研究，包括光合作用和猝灭色素、核酮糖1,5二磷酸羧化酶（Rubisco）、碳水化合物和蛋白质。短时间尺度（分钟）的反应将通过测量光合作用诱导和Rubisco活化和失活的动力学来评估。短时间尺度的实验将被解释为细胞在长时间的黑暗之后承受短暂的强光照射的能力。预计这项研究将导致一个更相关的框架来解释河口栖息地的波动光效应，而不考虑周期性禁闭在黑暗中的生理“成本”。

This research is designed to test the effects of extended darkness on the photosynthetic competence of benthic and planktonic diatoms. Lagrangian models of estuarine light fields surrounding phytoplankton and benthic algae indicate that exposure to darkness for from 2 5 days is a common occurrence. Preliminary evidence indicates that there is considerable species variation in the physiological competence after several days of darkness but the factors accounting for these differences are unknown. Metabolic and physiological changes during extended darkness are hypothesized to alter the photosynthetic apparatus and the subsequently ability of the cell to respond to light. The research focuses on two time scales of photosynthetic regulation. The extended time scale of hours days will be studied using measurements of the change in photosynthetic components including photosynthetic and quenching pigments, ribulose1,5 bisphosphate carboxylaseloxygenase (Rubisco), carbohydrate and protein. Short time-scale (minutes) responses will be evaluated using measurements of the kinetics of photosynthetic induction and of Rubisco activation and deactivation. Short time scale experiments will be interpreted in the context of the ability of cells to withstand brief exposures to bright light subsequent to prolonged darkness. It is anticipated that this research will lead to a more relevant framework for interpreting fluctuating light effects in estuarine habitats than can be had without considering the physiological 'costs' of periodic confinement to darkness.