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  • 1
    Publication Date: 2008-08-01
    Description: Natural selection dictates that cells constantly adapt to dynamically changing environments in a context-dependent manner. Gene-regulatory networks often mediate the cellular response to perturbation, and an understanding of cellular adaptation will require experimental approaches aimed at subjecting cells to a dynamic environment that mimics their natural habitat. Here we monitor the response of Saccharomyces cerevisiae metabolic gene regulation to periodic changes in the external carbon source by using a microfluidic platform that allows precise, dynamic control over environmental conditions. We show that the metabolic system acts as a low-pass filter that reliably responds to a slowly changing environment, while effectively ignoring fast fluctuations. The sensitive low-frequency response was significantly faster than in predictions arising from our computational modelling, and this discrepancy was resolved by the discovery that two key galactose transcripts possess half-lives that depend on the carbon source. Finally, to explore how induction characteristics affect frequency response, we compare two S. cerevisiae strains and show that they have the same frequency response despite having markedly different induction properties. This suggests that although certain characteristics of the complex networks may differ when probed in a static environment, the system has been optimized for a robust response to a dynamically changing environment.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2654342/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2654342/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bennett, Matthew R -- Pang, Wyming Lee -- Ostroff, Natalie A -- Baumgartner, Bridget L -- Nayak, Sujata -- Tsimring, Lev S -- Hasty, Jeff -- F32 GM082168/GM/NIGMS NIH HHS/ -- F32 GM082168-01/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 Aug 28;454(7208):1119-22. doi: 10.1038/nature07211. Epub 2008 Jul 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18668041" target="_blank"〉PubMed〈/a〉
    Keywords: Carbon/metabolism/pharmacology ; Culture Media/chemistry/pharmacology ; *Environment ; Galactose/metabolism/pharmacology ; *Gene Expression Regulation, Fungal ; Glucose/metabolism/pharmacology ; Half-Life ; Metabolic Networks and Pathways/*genetics ; Microfluidics ; RNA Stability ; RNA, Fungal/genetics/metabolism ; Saccharomyces cerevisiae/classification/drug effects/*genetics/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2008-10-31
    Description: One defining goal of synthetic biology is the development of engineering-based approaches that enable the construction of gene-regulatory networks according to 'design specifications' generated from computational modelling. This approach provides a systematic framework for exploring how a given regulatory network generates a particular phenotypic behaviour. Several fundamental gene circuits have been developed using this approach, including toggle switches and oscillators, and these have been applied in new contexts such as triggered biofilm development and cellular population control. Here we describe an engineered genetic oscillator in Escherichia coli that is fast, robust and persistent, with tunable oscillatory periods as fast as 13 min. The oscillator was designed using a previously modelled network architecture comprising linked positive and negative feedback loops. Using a microfluidic platform tailored for single-cell microscopy, we precisely control environmental conditions and monitor oscillations in individual cells through multiple cycles. Experiments reveal remarkable robustness and persistence of oscillations in the designed circuit; almost every cell exhibited large-amplitude fluorescence oscillations throughout observation runs. The oscillatory period can be tuned by altering inducer levels, temperature and the media source. Computational modelling demonstrates that the key design principle for constructing a robust oscillator is a time delay in the negative feedback loop, which can mechanistically arise from the cascade of cellular processes involved in forming a functional transcription factor. The positive feedback loop increases the robustness of the oscillations and allows for greater tunability. Examination of our refined model suggested the existence of a simplified oscillator design without positive feedback, and we construct an oscillator strain confirming this computational prediction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stricker, Jesse -- Cookson, Scott -- Bennett, Matthew R -- Mather, William H -- Tsimring, Lev S -- Hasty, Jeff -- GM69811-01/GM/NIGMS NIH HHS/ -- R01 GM069811/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 Nov 27;456(7221):516-9. doi: 10.1038/nature07389. Epub 2008 Oct 29.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18971928" target="_blank"〉PubMed〈/a〉
    Keywords: Computer Simulation ; Escherichia coli/*genetics ; Feedback ; Flow Cytometry ; *Gene Expression Regulation, Bacterial ; Gene Regulatory Networks/*genetics ; Genes, Synthetic/*genetics ; *Genetic Engineering ; Luminescent Measurements ; Microfluidic Analytical Techniques ; Models, Genetic ; *Periodicity ; Sensitivity and Specificity ; Time Factors ; Transcription Factors/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2011-12-20
    Description: Although there has been considerable progress in the development of engineering principles for synthetic biology, a substantial challenge is the construction of robust circuits in a noisy cellular environment. Such an environment leads to considerable intercellular variability in circuit behaviour, which can hinder functionality at the colony level. Here we engineer the synchronization of thousands of oscillating colony 'biopixels' over centimetre-length scales through the use of synergistic intercellular coupling involving quorum sensing within a colony and gas-phase redox signalling between colonies. We use this platform to construct a liquid crystal display (LCD)-like macroscopic clock that can be used to sense arsenic via modulation of the oscillatory period. Given the repertoire of sensing capabilities of bacteria such as Escherichia coli, the ability to coordinate their behaviour over large length scales sets the stage for the construction of low cost genetic biosensors that are capable of detecting heavy metals and pathogens in the field.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259005/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259005/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Prindle, Arthur -- Samayoa, Phillip -- Razinkov, Ivan -- Danino, Tal -- Tsimring, Lev S -- Hasty, Jeff -- P50GM085764/GM/NIGMS NIH HHS/ -- R01 GM069811/GM/NIGMS NIH HHS/ -- R01 GM069811-01A1/GM/NIGMS NIH HHS/ -- R01GM69811/GM/NIGMS NIH HHS/ -- England -- Nature. 2011 Dec 18;481(7379):39-44. doi: 10.1038/nature10722.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22178928" target="_blank"〉PubMed〈/a〉
    Keywords: Ampicillin/pharmacology ; Anti-Bacterial Agents ; Arsenic/*analysis ; Bacterial Proteins/metabolism ; Biological Clocks/drug effects ; *Biosensing Techniques ; Catalase/metabolism ; Escherichia coli/drug effects/enzymology/*genetics/*physiology ; *Gene Expression Regulation, Bacterial ; Hydrogen Peroxide/metabolism ; Kanamycin/pharmacology ; Liquid Crystals ; NADH Dehydrogenase/metabolism ; Oxidation-Reduction ; Quorum Sensing ; Superoxide Dismutase/metabolism ; Synthetic Biology ; Thiourea/pharmacology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2014-04-11
    Description: One promise of synthetic biology is the creation of genetic circuitry that enables the execution of logical programming in living cells. Such 'wet programming' is positioned to transform a wide and diverse swathe of biotechnology ranging from therapeutics and diagnostics to water treatment strategies. Although progress in the development of a library of genetic modules continues apace, a major challenge for their integration into larger circuits is the generation of sufficiently fast and precise communication between modules. An attractive approach is to integrate engineered circuits with host processes that facilitate robust cellular signalling. In this context, recent studies have demonstrated that bacterial protein degradation can trigger a precise response to stress by overloading a limited supply of intracellular proteases. Here we use protease competition to engineer rapid and tunable coupling of genetic circuits across multiple spatial and temporal scales. We characterize coupling delay times that are more than an order of magnitude faster than standard transcription-factor-based coupling methods (less than 1 min compared with approximately 20-40 min) and demonstrate tunability through manipulation of the linker between the protein and its degradation tag. We use this mechanism as a platform to couple genetic clocks at the intracellular and colony level, then synchronize the multi-colony dynamics to reduce variability in both clocks. We show how the coupled clock network can be used to encode independent environmental inputs into a single time series output, thus enabling frequency multiplexing (information transmitted on a common channel by distinct frequencies) in a genetic circuit context. Our results establish a general framework for the rapid and tunable coupling of genetic circuits through the use of native 'queueing' processes such as competitive protein degradation.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142690/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142690/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Prindle, Arthur -- Selimkhanov, Jangir -- Li, Howard -- Razinkov, Ivan -- Tsimring, Lev S -- Hasty, Jeff -- P50 GM085764/GM/NIGMS NIH HHS/ -- R01 GM069811/GM/NIGMS NIH HHS/ -- England -- Nature. 2014 Apr 17;508(7496):387-91. doi: 10.1038/nature13238. Epub 2014 Apr 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA [2]. ; Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA. ; BioCircuits Institute, University of California, San Diego, La Jolla, California 92093, USA. ; 1] Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA [2] BioCircuits Institute, University of California, San Diego, La Jolla, California 92093, USA [3] Molecular Biology Section, Division of Biological Science, University of California, San Diego, La Jolla, California 92093, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24717442" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/genetics/metabolism ; Biological Clocks/genetics ; *Gene Regulatory Networks ; Peptide Hydrolases/metabolism ; *Protein Biosynthesis ; *Proteolysis ; Signal Transduction ; Synthetic Biology ; Time Factors ; Transcription Factors/metabolism ; Transcription, Genetic
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    ISSN: 1572-9613
    Keywords: Random pinning ; gradient models ; localized structures ; spatiotemporal chaos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The birth of spatial disorder from almost regular initial conditions within the Swift-Hohenberg model equation with subcritical bifurcation is considered. The complexity of the space series (measured by the spatialK 2-entropy) grows with time and reaches a stationary value depending on the period of the initial regular disturbance. A qualitative model is suggested describing the process via the birth of localized structures and its subsequent disordering due to weak interaction.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2011-12-12
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 7
    Publication Date: 1994-07-01
    Print ISSN: 1063-651X
    Electronic ISSN: 1095-3787
    Topics: Physics
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  • 8
    Publication Date: 1999-01-25
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
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  • 9
    Publication Date: 1992-12-01
    Print ISSN: 1050-2947
    Electronic ISSN: 1094-1622
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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  • 10
    Publication Date: 2001-11-28
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
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