Abstract：
Despite a global prevalence of photosynthetic organisms in the ocean\'s mesophotic zone (30-200+ m depth), the mechanisms that enable photosynthesis to proceed in this low light environment are poorly defined. Red coralline algae are the deepest known marine benthic macroalgae - here we investigated the light harvesting mechanism and mesophotic acclimatory response of the red coralline alga Lithothamnion glaciale.
Following initial absorption by phycourobilin and phycoerythrobilin in phycoerythrin, energy was transferred from the phycobilisome to photosystems I and II within 120 ps. This enabled delivery of 94% of excitations to reaction centres. Low light intensity, and to a lesser extent a mesophotic spectrum, caused significant acclimatory change in chromophores and biliproteins, including a 10% increase in phycoerythrin light harvesting capacity and a 20% reduction in chlorophyll-a concentration and photon requirements for photosystems I and II. The rate of energy transfer remained consistent across experimental treatments, indicating an acclimatory response that maintains energy transfer.
Our results demonstrate that responsive light harvesting by phycobilisomes and photosystem functional acclimation are key to red algal success in the mesophotic zone.
Following initial absorption by phycourobilin and phycoerythrobilin in phycoerythrin, energy was transferred from the phycobilisome to photosystems I and II within 120 ps. This enabled delivery of 94% of excitations to reaction centres. Low light intensity, and to a lesser extent a mesophotic spectrum, caused significant acclimatory change in chromophores and biliproteins, including a 10% increase in phycoerythrin light harvesting capacity and a 20% reduction in chlorophyll-a concentration and photon requirements for photosystems I and II. The rate of energy transfer remained consistent across experimental treatments, indicating an acclimatory response that maintains energy transfer.
Our results demonstrate that responsive light harvesting by phycobilisomes and photosystem functional acclimation are key to red algal success in the mesophotic zone.
摘要：
背景：尽管光合生物在海洋中区（30-200+m深度）的全球普遍存在，在这种弱光环境中进行光合作用的机制尚不清楚。红色珊瑚藻是已知最深的海洋底栖大型藻类-在这里，我们研究了红色珊瑚藻Lithmothamnion冰川的集光机制和中观调节响应。
结果：在藻红蛋白中最初被藻胆素和藻胆素吸收后，能量在120ps内从藻胆体转移到光系统I和II。这使得能够向反应中心递送94%的激发。低光照强度,在较小程度上是介观光谱，在发色团和胆红素中引起明显的不稳定变化，包括藻红蛋白集光能力增加10％，叶绿素a浓度和光系统I和II的光子需求减少20％。能量转移速率在实验处理中保持一致，表明维持能量转移的适应反应。
结论：我们的结果表明，通过藻胆体和光系统功能适应的响应性光捕获是在中透带红藻成功的关键。
结果：在藻红蛋白中最初被藻胆素和藻胆素吸收后，能量在120ps内从藻胆体转移到光系统I和II。这使得能够向反应中心递送94%的激发。低光照强度,在较小程度上是介观光谱，在发色团和胆红素中引起明显的不稳定变化，包括藻红蛋白集光能力增加10％，叶绿素a浓度和光系统I和II的光子需求减少20％。能量转移速率在实验处理中保持一致，表明维持能量转移的适应反应。
结论：我们的结果表明，通过藻胆体和光系统功能适应的响应性光捕获是在中透带红藻成功的关键。
