据介绍，光周期时间测量是植物和动物测量昼夜长度（光周期）差异的能力，并利用这些信息预测关键的季节变化，如年温度周期。这种计时现象会触发高等生物的适应性反应，如性腺刺激、开花和冬眠。
出乎意料的是，研究人员在蓝藻（单细胞原核生物）中观察到了这种能力，其产生时间短至5至6小时。暴露在短时间冬季环境中的蓝藻对寒冷的抵抗力增强，这是由膜脂质的去饱和和基因转录的差异程序（包括应激反应途径）介导的。
与真核生物一样，这种光周期计时需要一个完整的生物钟，并在多个光周期内发展。因此，光周期计时在比以前认识到的更简单的生物体中演化，并使遗传反应能够对季节性反复出现的压力做出反应。
附：英文原文
Title: Bacteria can anticipate the seasons: Photoperiodism in cyanobacteria
Author: Maria Luísa Jabbur, Benjamin P. Bratton, Carl Hirschie Johnson
Issue&Volume: 2024-09-06
Abstract: Photoperiodic time measurement is the ability of plants and animals to measure differences in day versus night length (photoperiod) and use that information to anticipate critical seasonal transformations, such as annual temperature cycles. This timekeeping phenomenon triggers adaptive responses in higher organisms, such as gonadal stimulation, flowering, and hibernation. Unexpectedly, we observed this capability in cyanobacteria—unicellular prokaryotes with generation times as short as 5 to 6 hours. Cyanobacteria exposed to short, winter-like days developed enhanced resistance to cold mediated by desaturation of membrane lipids and differential programs of gene transcription, including stress response pathways. As in eukaryotes, this photoperiodic timekeeping required an intact circadian clockwork and developed over multiple cycles of photoperiod. Therefore, photoperiodic timekeeping evolved in much simpler organisms than previously appreciated and enabled genetic responses to stresses that recur seasonally.
DOI: ado8588
Source: https://www.science.org/doi/10.1126/science.ado8588