有害褐潮生物抑食金球藻（Aureococcus anophagefferens）对蓝光生理响应的信号传递与调控机制

The picoplanktonic harmful algal bloom species, Aureococcus anophagefferens, have caused devastating effects in the coastal waters of the United States, South Africa and China. Preliminary field investigations showed that A. anophagefferens cells were almost evenly distributed at the surface and bottom of seawater, indicating they have strong adaptability to different light intensity and light quality. Blue wavebands predominate in deeper water due to their shorter wavelengths and high energy. For organisms living in deep water, blue light is the major spectra available for photosynthesis. A. anophagefferens can avoid photosynthetic system damage caused by blue light radiation and eventually form algal blooms, indicating they have strong abilities to protect themselves against blue light illumination. However, the regulatory mechanism is still unclear. In our project, the brown tide species A. anophagefferens were selected as the experimental research objects to investigate the characteristics of light energy absorption and utilization under blue light, and to reveal the mechanisms of light protection and energy dissipation. Furthermore, we hope to elucidate the signal reception and regulation mechanisms of aureochromes by performing the gene screening and bioinformatics analysis of aureochromes in A. anophagefferens. This project can explore the physiological response mechanisms of A. anophagefferens to blue light, and can further reveal the function and significance of aureochromes which only found in heterokont algae. It can also provide ideas for the light response mechanisms of brown tide blooms.

抑食金球藻是一种微微型有害藻华生物，在美国、南非和中国近海海域爆发“褐潮”并造成破坏性影响。前期现场调查表明，抑食金球藻褐潮爆发时，该藻在表底层几近均匀分布，表明其对海水表底层不同光强和光质具有较强的适应能力。蓝光在水体中的透射能力强，能量高，是深层水体中能被光合利用的主要光线，抑食金球藻能够避免蓝光辐射造成的光合系统损伤而最终形成藻华，说明具有较强应对蓝光的光保护能力，但机制尚不明确。本项目拟以褐潮生物抑食金球藻为研究对象，通过蓝光诱导胁迫抑食金球藻，挖掘其在蓝光中的光能吸收和利用特点，揭示其应对蓝光的光保护机制和能量耗散途径；对抑食金球藻的蓝光受体进行基因筛选和生物信息学分析，阐明蓝光受体在蓝光中的信号接收与调控作用机制。本项目的实施可在探明抑食金球藻对蓝光的生理响应机制基础上，揭示蓝光受体仅存在于不等鞭毛藻中的功能和意义，还可为褐潮爆发的光响应机制提供研究思路。

中国渤海湾沿岸是褐潮频繁暴发的海域，抑食金球藻是褐潮暴发的主要肇事种。本研究通过现场海域监测，发现抑食金球藻呈现明显的表底均匀分布特征。由于蓝光具有强大的水体穿透能力，因此抑食金球藻对蓝光可能具有独特的响应能力。本研究通过实验室模拟蓝光环境，探究抑食金球藻的光生理响应特征及分子调控机制。在蓝光环境中，抑食金球藻通过降低光合效率和电子传递效率，减少光能的吸收。同时，通过非光化学淬灭的方式耗散过剩能量。抑食金球藻含有硅甲藻黄素循环和19’-丁酰氧基岩藻黄素循环，在蓝光环境下通过色素循环辅助进行能量耗散。抑食金球藻含有丰富的光捕获蛋白，其中Lhc27、Lhc37和Lhc42在蓝光环境中表达量上调，积极参与光合压力信号的传递。蓝光环境下视黄醛脱氢酶表达量上调，促进藻细胞内潜在致畸物质视黄醛浓度的增加，对水生生物产生潜在的致畸效应。本研究发现抑食金球藻含有5种隐花色素作为蓝光感受器，其中AURANDRAFT_20741与Cry-1系统发育接近，对蓝光环境的变化更为敏感。本项目探究了抑食金球藻在蓝光环境中进行响应的关键基因和调控机制，揭示了其耗散过剩能量的具体方式，为褐潮暴发提供光响应理论依据。同时对蓝光照射下其代谢过程中积累的潜在有毒物质进行深入研究，为揭示藻华过程中可能产生的生态影响提供数据支持。