Examining the impact arrhythmic gene expression has on fitness in cyanobacteria possessing a complete circadian clock

检查心律失常基因表达对拥有完整生物钟的蓝藻健康的影响

• 批准号: 9899110
• 负责人: Dustin C Ernst
• 金额: $ 6.12万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-05 至 2021-09-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9899110
• 关键词: Address; Alleles; Animal Model; Animals; Area; Behavior; Biological Assay; Biological Clocks; Biological Models; Biological Rhythm; Biology; Cell physiology; Cellular Metabolic Process; Circadian Dysregulation; Circadian Rhythms; Coupled; Cyanobacterium; Data; Defect; Dietary Practices; Disadvantaged; Disease; Environment; Eukaryota; Exposure to; Future; Gene Expression; Gene Expression Regulation; Genes; Genetic; Genetic Determinism; Genetic Screening; Growth; Homeostasis; Hour; Human; Hybrids; Insertion Mutation; Intervention; Life; Light; Mediating; Metabolism; Modeling; Modernization; Open Reading Frames; Organism; Output; Pattern; Peptides; Periodicity; Phenotype; Phosphorylation; Play; Pollution; Research; Role; Synechococcus; System; Testing; Time; Tissues; Travel; Work; Yeasts; base; circadian; circadian pacemaker; cost; experience; experimental study; fitness; fitness test; health management; improved; metabolic profile; mutant; polypeptide; programs; response; shift work; transposon sequencing

ABSTRACT Circadian rhythms controlled by intrinsic biological clocks enable anticipatory changes in cellular physiology to promote adaptation to daily environmental cycles. The pervasiveness of circadian programs among eukaryotes and cyanobacteria suggests that circadian clocks confer a fitness advantage to organisms exposed to fluctuating growth environments. Despite the ubiquity of circadian clocks, the specific benefits of circadian systems to overall fitness have remained elusive. Previous studies in the model cyanobacterium Synechococcus elongatus PCC 7942 demonstrated that cyanobacteria whose circadian period closely matches the external light cycle are more fit than strains with periods that differ. Importantly, these studies relied on mutants with defective core clocks, which resulted in previously unappreciated pleiotropic consequences. Here, we propose to test the fitness benefit of circadian rhythms in cyanobacteria using a strain that is unable to produce oscillations in gene expression despite possessing an intact circadian clock, in order to avoid biases encountered by clock mutants. The previously described crm1 mutant contains a transposon insertion in the crm (circadian rhythmicity modulator) ORF that results in arrhythmic expression of clock controlled genes. The crm1 allele elicits phenotypes distinct from arrhythmic kaiC-null and rpaA-null strains, and the crm1 mutant grows in alternating light-dark cycles, providing a strain with moderate arrhythmic gene expression ideal for fitness studies. Competition experiments between the arrhythmic crm1 mutant and WT or other arrhythmic mutants, coupled with metabolic profiles and high-throughput TnSeq-based genetic interaction screens in the crm1 background, will improve our understanding of the fitness consequences encountered by cyanobacteria that fail to maintain rhythmic gene expression. Furthermore, this work is intended to characterize the RpaA-modulating activity of the enigmatic Crm peptide, adding to our model of factors that influence clock output. Taken together, this work has the potential to inform future studies regarding clock-controlled fitness in humans. It is becoming increasingly apparent that the toll of modern life – including shiftwork, blue-light exposure, jet travel and other behaviors – can profoundly disrupt circadian programs in a variety of mammalian tissues, contributing to disease. Our ability to assess the fitness advantage of biological clocks in mammalian tissues is limited, necessitating tractable model organisms such as S. elongatus to investigate fitness components of the clock network. The work may provide a framework for future understanding and treatment of circadian disruption in humans.

抽象的 由内在生物钟控制的昼夜节律使细胞生理学的预期变化能够 促进对日常环境循环的适应。真核生物中昼夜节律程序的普遍性 蓝细菌表明，生物钟赋予生物体以适应波动的优势 成长环境。尽管生物钟无处不在，但昼夜节律系统对整体的具体好处 健身仍然难以实现。先前对蓝藻细长聚球藻 PCC 模型的研究 7942 证明昼夜节律与外部光周期密切匹配的蓝藻细菌更容易 比时期不同的菌株更适合。重要的是，这些研究依赖于核心时钟有缺陷的突变体， 这导致了以前未曾意识到的多效性后果。在这里，我们建议测试一下健身效果 使用无法产生基因表达振荡的菌株来研究蓝细菌的昼夜节律 尽管拥有完整的生物钟，以避免时钟突变体遇到的偏差。这 先前描述的 crm1 突变体在 crm（昼夜节律调节剂）中包含转座子插入 ORF 导致时钟控制基因的心律失常表达。 crm1 等位基因引发不同的表型 来自心律失常的 kaiC-null 和 rpaA-null 菌株，并且 crm1 突变体在交替的光暗循环中生长， 提供具有中度心律失常基因表达的菌株，非常适合健身研究。竞赛实验 心律失常 crm1 突变体和 WT 或其他心律失常突变体之间的关系，以及代谢特征和 crm1 背景下基于高通量 TnSeq 的遗传相互作用筛选，将改善我们的 了解无法维持节律基因的蓝藻所遇到的适应性后果 表达。此外，这项工作旨在表征神秘的 RpaA 调节活性 Crm 肽，添加到我们影响时钟输出的因素模型中。综合起来，这部作品有 可能为未来有关人类时钟控制健康的研究提供信息。它正变得越来越 显然，现代生活的代价——包括轮班工作、蓝光暴露、乘坐飞机旅行和其他行为—— 可以严重扰乱多种哺乳动物组织的昼夜节律，从而导致疾病。我们的能力 评估哺乳动物组织中生物钟的适应性优势是有限的，需要易于处理的 模型生物，如 S. elongatus，用于研究时钟网络的适应性组成部分。该工作可能 为未来理解和治疗人类昼夜节律紊乱提供一个框架。