城市夜光对鸟类生物钟系统的影响

In order to adapt to the temporal environment, living organisms have envolved an internal biological clock system to integrate cyclic environmental information with internal clock,so that they can predict enivronmental change and timing their physiology and behavior. Urban night light disrupts the clock system and affects its regulation on the biological rhythms. The proposed project will integrate ecology, animal physiology and chronobiology，and focus on the biological clock system of Eurasian tree sparrow, Passer domesticus from both urban and rural populations among different seasons. First, we will measure and compare the light environment which birds are actually experiencing between urban and rural habitats. Then we will perform captive study with lab-simulated urban or rural night light conditions to investigate the effects of urban night light on the regulation of physiological and behavioral rhythms by the avian clock system. In addition, by surgically removing the pineal gland and rhythmic melatonin injections, we will explore the mediating effect of the pineal gland. Finally, we will investigate the internal differences of the clock systems on their regulations of circadian rhythms between urban and rural populations. We hypothesize: (1) Urban night light affects the regulations of the biological rhythms by the clock system in sparrow. (2) The pineal gland plays a major role in mediating the effects of urban night light on the avian biological clock. The predicted results from this project will not only make significant contributions to the regulatory mechnisms and ecological adaptation of the avian clock system, but also establish the theoretical basis for the strategy of wildlife conservation under urbanization from the perspective of the biological rhythms.

通过生物钟系统对周期性环境信息与内源时间信息的整合,生命有机体能够预测环境变化并调整自身的生理行为节律，从而更好的适应生态环境。城市夜光干扰了生物钟系统并影响了其对生物节律的调节。本项目结合生态学、动物生理学和时间生物学的研究方法，通过对不同季节城市和郊外树麻雀(Passer domesticus)所处光环境的测量比较，实验室模拟不同夜光环境下生物钟所控生理行为节律的差异，松果体摘除和褪黑素周期性注射对夜光反应的影响，以及城市和郊外树麻雀生物钟对内在昼夜节律调节差异的比较，验证：（1）城市夜光改变了树麻雀生物钟对生物节律的调节。（2）松果体介导了夜光对鸟类生物钟的影响。本项目的预期结果不仅对鸟类生物钟系统的调节机制和生态适应研究具有重要贡献，并且为从生物节律的角度探讨城市化下野生动物的保护措施奠定了理论基础。

城市和乡村的光环境有明显的差异，尤其是城市夜晚的照明已经对生物多样性造成威胁。然而城市夜光对鸟类的行为活动节律，褪黑素分泌水平及其受体基因表达的影响却仍缺乏研究。我们以西安市为调查区，在选择样地和样点的基础上，应用光谱仪分析城市中麻雀分布的典型生境（居民区、校园和公园）和乡村（农田）的光环境的差异。结果显示城市中夜晚的光照强度的均值是8±0.53lux，而乡村的夜晚光照强度接近于0，城市夜光环境和乡村相比有明显差异。在此基础上，通过室内模拟城市夜光环境和乡村夜光环境来说明城市夜光对麻雀行为的昼夜节律，褪黑素分泌水平和褪黑素A型受体，B型受体和C型受体基因的mRNA表达水平的影响。模拟城市的光环境是白天13小时光照，晚上11小时8 lux弱光照。模拟乡村的光环境是白天13小时晚上11小时黑暗。结果显示，城市夜光并未改变麻雀行为昼夜节律的周期性，但是城市夜光导致麻雀的自主行为活动开始的时间提前；无论是乡村还是城市，夜晚的褪黑素分泌水平均显著高于白天。但是乡村夜晚模拟环境下的麻雀的褪黑素分泌水平显著高原城市夜光模拟下的麻雀，城市夜光抑制了鸟类褪黑素的分泌水平；无论是白天还是夜晚，模拟城市夜光环境下的麻雀的褪黑素A型受体，B型受体和C型受体基因的mRNA在脑的表达水平显著低于模拟乡村环境下的麻雀，而褪黑素C型受体基因的mRNA在肝脏的表达水平也显著低于乡村环境模拟下的麻雀，而褪黑素B型受体基因的mRNA在眼中的表达水平也显著低于模拟乡村环境下的麻雀，褪黑素A型受体基因的mRNA在白天的表达则显著高于乡村，而褪黑素C型受体基因的mRNA在夜晚的表达则显著高于乡村。总之，城市夜光影响了鸟类的昼夜节律，抑制了鸟类的褪黑素的分泌水平，也抑制了褪黑素受体在不同器官的mRNA的表达水平。本研究可以为光污染对鸟类行为节律和激素分泌水平的研究提供数据支持，也为光污染条件下生物多样性的保护提供参考。