生物钟与光周期响应

浩瀚宇宙中,地球自转的同时围绕太阳的公转导致昼夜交替,四季更迭,风物长新。正因如此,地球生命赖以存在的自然环境中的光照、温度、水分(湿度)、食物(营养)等环境因素也会发生相应的周期性变化。生物体只有适应环境节律性变化带来的生存压力才能保证种族的繁衍。所有的环境适应性中,生物体对光周期的适应最为重要。处于地球上不同纬度的生物,在一年之中感受到光强、光质和光照长度的节律性变化,会在最适的时间选择适宜的环境完成生长、发育和繁殖过程。在漫长进化过程中产生的生物钟调控机制,可以帮助生物体整合并预测内外环境信号近24小时节律性变化,进而通过调控机体生理生化和新陈代谢过程提高环境适应性。生物学家一直关注生物钟与光周期现象,相关领域已有许多重要研究成果表明生物钟参与调控动植物的光周期响应。

Circadian clock and photoperiodism

Within this vast universe, the earth rotates on its axis, and also orbits around the sun, which creates rapid changes of day andnight and the seasons of the year. For these reasons, the natural cues of light, temperature, humidity, nutrition and other environmental factors essential for individual survivals change periodically. The organisms have to adapt to the environment caused by the selective pressures to ensure their reproduction. Of all the fitness, the adaptation to light/dark cycles is most important. Creatures at different latitudes on the earth experience the rhythmicity of sunlight intensity, variable range of light quality and illumination length during the year, and they choose the suitable location to complete the growth, development and reproduction. Evolution has instated the timekeeping mechanism from circadian clock to confer organisms the ability to integrate and foresee the daily and seasonal changes in light exposure, and then improved survival rate by scheduling the physical and metabolic process at the most appropriate time. The studies concerned with the functional connection between biological clock and photoperiodism, and the more results shown that the circadian oscillators are involved in the regulation of plant’s or animal’s capacity to respond to the photoperiod.