Horikawa Yu, Watanabe Emiri, Ito Shogo, Oyama Tokitaka
Department of Botany, Graduate School of Science, Kyoto University.
Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo.
Plant Biotechnol (Tokyo). 2025 Jun 25;42(2):173-177. doi: 10.5511/plantbiotechnology.24.1226a.
Bioluminescence monitoring techniques are widely used to study the gene expression dynamics in living plants. Monitoring the bioluminescence from a luciferase gene under the control of a circadian promoter is indispensable for examining plant circadian systems. The bioluminescence monitoring technique was successfully applied to physiological studies of circadian rhythms in duckweed plants. It has been reported that a luciferase gene under a constitutive promoter also exhibits a bioluminescent circadian rhythm in duckweed. However, the mechanisms underlying rhythm generation remain unknown. In this study, we performed a model-based analysis to evaluate the machinery that generates the bioluminescence rhythm. We hypothesized the rhythmic factor of three aspects regarding the bioluminescence intensities of luciferase in cells: luminescence efficiency, production rate, and degradation rate. Theoretically, if the latter two are involved in rhythm generation, the difference in luciferase stability affects the amplitude and phase relations of the bioluminescence rhythm. Luciferase stability is irrelevant to these rhythm properties if only the luminescence efficiency is involved. First, we simulated the bioluminescence rhythms of two luciferases with different stabilities associated with each of three rhythmic factors. Luciferase stability was set based on the reported values for Emerald-luciferase and Emerald-luciferase-PEST. We then experimentally examined the bioluminescence rhythms of reporters of these luciferases driven by the promoter in the duckweed . Their circadian properties matched those obtained from the simulation of the luminescence efficiency. This supports the view that cells in duckweed show circadian changes in physiological conditions associated with the luciferase enzyme reaction.
生物发光监测技术被广泛用于研究活植物中的基因表达动态。监测由昼夜节律启动子控制的荧光素酶基因发出的生物发光对于研究植物昼夜节律系统是必不可少的。生物发光监测技术已成功应用于浮萍植物昼夜节律的生理学研究。据报道，组成型启动子控制下的荧光素酶基因在浮萍中也表现出生物发光昼夜节律。然而，节律产生的潜在机制仍然未知。在本研究中，我们进行了基于模型的分析，以评估产生生物发光节律的机制。我们假设了关于细胞中荧光素酶生物发光强度的三个方面的节律因子：发光效率、产生速率和降解速率。从理论上讲，如果后两者参与节律产生，荧光素酶稳定性的差异会影响生物发光节律的幅度和相位关系。如果仅涉及发光效率，荧光素酶稳定性与这些节律特性无关。首先，我们模拟了与三个节律因子中的每一个相关的具有不同稳定性 的两种荧光素酶的生物发光节律。荧光素酶稳定性是根据报道的Emerald-荧光素酶和Emerald-荧光素酶-PEST的值设定的。然后，我们通过实验检测了浮萍中由该启动子驱动的这些荧光素酶报告基因的生物发光节律。它们的昼夜节律特性与从发光效率模拟中获得的特性相匹配。这支持了浮萍细胞在与荧光素酶酶反应相关的生理条件下表现出昼夜变化的观点。
