記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.5511/plantbiotechnology.13.0605a

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/pcp/pcs095

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記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Nova Science Publishers, Inc.  

In cyanobacteria, bioluminescence reporters have been applied to the measurement of physiological phenomenon, such as in the study of circadian clock and nitrite, ferric, and light responses. Cyanobacterial researchers have so far used several types of bioluminescence reporter systems-consisting of luminescence genes, genetically tractable host cells, and a monitoring device-because their studies require a method that offers gene expression data with high fidelity, high resolution for time, and enough dynamic range in data collection. In addition, no extraction of the products of the reporter gene from the culture is required to measure the luminescence, even in the living cell. In this chapter, applications using the bioluminescence genes luxAB (and luxCDE for substrate production) and insect genes are introduced. For measurement and imaging, general apparatuses, such as a luminometer and a luminoimager, have been used with several methods of substrate administration. Automated bioluminescence monitoring apparatuses were also newly developed. The initial machine was similar to that used to measure the native circadian rhythms in bioluminescence of the marine dinoflagellate Gonyaulax polyedra. Then, the machine with a cooled CCD camera which was automatically operated by a computer was used to screen mutant colonies representing abnormal bioluminescence profile or level from a mutagen-treated cyanobacterial cell with a luxAB reporter. Recently, different two promoter activities could be examined in the same cell culture and with the same timing by using railroad-worm luciferase genes. © 2009 Nova Science Publishers, Inc. All rights reserved.

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1128/JB.00835-07

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1074/jbc.m608148200

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担当区分：最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：SAGE Publications  

The time measurement system of the unicellular cyanobacterium Synechococcus elongatus PCC 7942 is analogous to the circadian clock of eukaryotic cells. Circadian clock-related genes have been identified in this strain. The clock-related gene pex is thought to maintain the normal clock period because constitutive transcription or deficiency of this gene causes respectively longer (~28 h) or shorter (~24 h) circadian periods than that of the wild type (~25 h). Here, the authors report other properties of pex in the circadian system. Levels of pex mRNA increased significantly in a 12-h exposure to darkness. Western blotting with a GST-Pex antibody revealed a 13.5-kDa protein band in wild-type cells that were incubated in the dark, while this protein was not detected in pex-deficient mutant cells. Therefore, the molecular weight of the Pex protein appears to be 13.5 kDa in vivo. The PadR domain, which is conserved among DNA-binding transcription factors in lactobacilli, was found in Pex. In the pex mutant, several 12-h light/12-h dark cycles reset the phase of the clock by 3 h earlier (phase advance) compared to wild-type cells. The degree of the advance in the pex mutant was proportional to the number of exposed light-dark cycles. In addition, ectopic induction of pex with an inducible Escherichia coli promoter, Ptrc, delayed the phase in the examined recombinant cells by 2.5 h (phase delay) compared to control cells. These results suggest that the dark-responsive gene expression of pex delays the circadian clock under daily light-dark cycles.

DOI： 10.1177/0748730406289400

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

DOI： 10.1111/j.1365-2958.2005.04781.x

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Proceedings of the National Academy of Sciences  

A kaiABC clock gene cluster was previously identified from cyanobacterium Synechococcus elongatus PCC 7942, and the feedback regulation of kai genes was proposed as the core mechanism generating circadian oscillation. In this study, we confirmed that the Kai-based oscillator is the dominant circadian oscillator functioning in cyanobacteria. We probed the nature of this regulation and found that excess KaiC represses not only kaiBC but also the rhythmic components of all genes in the genome. This result strongly suggests that the KaiC protein primarily coordinates genomewide gene expression, including its own expression. We also found that a promoter derived from E. coli is feedback controlled by KaiC and restores the complete circadian rhythm in kaiBC -inactivated arrhythmic mutants, provided it can express kaiB and kaiC genes at an appropriate level. Unlike eukaryotic models, specific regulation of the kaiBC promoter is not essential for cyanobacterial circadian oscillations.

DOI： 10.1073/pnas.0307411100

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/pcp/pcf176

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掲載種別：研究論文（学術雑誌）   出版者・発行元：American Association for the Advancement of Science (AAAS)  

Cyanobacteria are the simplest organisms known to have a circadian clock. A circadian clock gene cluster kaiABC was cloned from the cyanobacterium Synechococcus. Nineteen clock mutations were mapped to the three kai genes. Promoter activities upstream of the kaiA and kaiB genes showed circadian rhythms of expression, and both kaiA and kaiBC messenger RNAs displayed circadian cycling. Inactivation of any single kai gene abolished these rhythms and reduced kaiBC -promoter activity. Continuous kaiC overexpression repressed the kaiBC promoter, whereas kaiA overexpression enhanced it. Temporal kaiC overexpression reset the phase of the rhythms. Thus, a negative feedback control of kaiC expression by KaiC generates a circadian oscillation in cyanobacteria, and KaiA sustains the oscillation by enhancing kaiC expression.

DOI： 10.1126/science.281.5382.1519

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Society for Microbiology  

ABSTRACT

We cloned the pS1K1 plasmid in the process of apparently “complementing” a circadian clock mutant of cyanobacterium Synechococcus sp. strain PCC 7942, SP22, which has a 22-h period (T. Kondo, N. F. Tsinoremas, S. S. Golden, C. H. Johnson, S. Kutsuna, and M. Ishiura, Science 266:1233–1236, 1994). Sequence analysis revealed that SP22 did not have a mutation in the genomic DNA segment carried on pS1K1, and the sp22 mutation was later found in a recently cloned new clock gene, kaiC . Therefore, the period-extender gene pex that was carried on pS1K1 was a suppressor gene for the sp22 mutation. The pex gene encoded a protein of 148 amino acid residues. No meaningful homologs were found in DNA or protein databases including the Synechocystis genome database. The pex gene was transcribed from 129 and 164 bp upstream of the translation initiation codon as 0.6-kb transcripts. The Pex protein was detected as a fusion protein with a molecular mass of 15 kDa by the epitope tag fusion method using a c-Myc epitope tag. Disruption of the pex gene in wild-type cells shortened the period of the rhythms by 1 h, although it did not affect other properties of the rhythms, whereas its overexpression extended the period by 3 h with a concomitant reduction in the amplitude of the rhythms. In various clock mutants examined, overexpression caused arrhythmicity. Thus, Pex is likely to function as a modifier of the circadian clock in Synechococcus.

DOI： 10.1128/jb.180.8.2167-2174.1998

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掲載種別：研究論文（学術雑誌）   出版者・発行元：American Association for the Advancement of Science (AAAS)  

DOI： 10.1126/science.7973706

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会議種別：ポスター発表  

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会議種別：ポスター発表  

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会議種別：ポスター発表  

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会議種別：ポスター発表  

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記述言語：日本語   会議種別：ポスター発表  

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記述言語：日本語   会議種別：ポスター発表  

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記述言語：英語   会議種別：ポスター発表  

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記述言語：英語   会議種別：ポスター発表  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：ポスター発表  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：英語   会議種別：ポスター発表  

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