Berwanger Lutz Claus, Thumm Nikolaus, Stirba Florian Pascal, Gholamipoorfard Rahil, Pawlowski Alice, Kolkhof Petra, Volke Jeannine, Kollmann Markus, Wiegard Anika, Axmann Ilka Maria
Synthetic Microbiology, Heinrich Heine University Düsseldorf, Düsseldorf 40225, Germany.
Computational Systems Biology of Cancer, University of Cologne, Köln 50931, Germany.
PNAS Nexus. 2025 Apr 25;4(5):pgaf120. doi: 10.1093/pnasnexus/pgaf120. eCollection 2025 May.
Circadian clocks regulate biological activities, providing organisms with a fitness advantage under diurnal conditions by enabling anticipation and adaptation to recurring external changes. Three proteins, KaiA, KaiB, and KaiC, constitute the circadian clock in the cyanobacterial model PCC 7942. Several techniques established to measure circadian output in yielded comparably weak signals in sp. PCC 6803, a strain important for biotechnological applications. We applied an approach that does not require genetic modifications to monitor the circadian rhythms in and . We placed batch cultures in shake flasks on a sensor detecting backscattered light via noninvasive online measurements. Backscattering oscillated with a period of ∼24 h around the average growth. Wavelet and Fourier transformations are applied to determine the period's significance and length. In , oscillations fulfilled the circadian criteria of temperature compensation and entrainment by external stimuli. Remarkably, dilution alone synchronized oscillations. Western blotting revealed that the backscatter was ∼6.5 h phase-delayed in comparison to KaiC3 phosphorylation.
生物钟调节生物活动，通过使生物体能够预测并适应反复出现的外部变化，在昼夜条件下为其提供适应性优势。三种蛋白质，即KaiA、KaiB和KaiC，构成了蓝藻模式生物PCC 7942中的生物钟。已建立的几种用于测量生物钟输出的技术在集胞藻属PCC 6803（一种对生物技术应用很重要的菌株）中产生的信号相对较弱。我们应用了一种无需基因改造的方法来监测集胞藻属和聚球藻属中的昼夜节律。我们将分批培养物置于摇瓶中，通过非侵入性在线测量在一个检测反向散射光的传感器上进行监测。反向散射在平均生长周围以约24小时的周期振荡。应用小波变换和傅里叶变换来确定周期的显著性和长度。在聚球藻属中，振荡满足温度补偿和外部刺激诱导的昼夜节律标准。值得注意的是，仅稀释就能使振荡同步。蛋白质免疫印迹法显示，与KaiC3磷酸化相比，反向散射存在约6.5小时的相位延迟。
