Download - synthetic gene networks that count
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synthetic gene networks that count
Lv ChenChen
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A counter!!
A counter is a key component in digital circuits and computing that retains memory of events or objects, representing each number of such as a distinct state.
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Counter in cells
• processes or biomolecules to maintain metabolism and growth. • telomere length regulation • cell aggregation • threshold effect:( 门槛效应;识阈效应 )
• system behaviors• Critical• Observed phenotypic change.
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• Friedland et al. take important steps tobuild biological counters by integrating thesefunctional operations.• Two different circuit architectures for
encoding counters that trigger the expression of a desired protein following the processing of two or three input signal pulses.
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riboregulated transcriptional cascade(RTC) counter
• Riboregulators (cis and trans)
• a stem-loop structure• count brief arabinose
pulses
• RTC two-counter • promoter PLtet0-1• T7 RNA polymerase• downstream gene
(GFP)
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expected expression profiles
Arabinose 树胶醛醣
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RTC three-counter
expectedexpression profiles after zero, one,two, and three arabinose pulses
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Mean fluorescence ofthree replicates of RTC two/three-countercell populations over time, measured by a flow cytometer.
considerable slopeslight leakage temporal progression
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• Recombinase• Cre and flpe • loxP and
flperecombination target (FRT) sites
The DIC counter
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The DIC three-counter
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Mean fluorescence of single-inducer DIC three-counter cell populations over time
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GFP fluorescence ratios between the single-inducer DIC three-counter exposed to three pulses of arabinose (N)versus two pulses of arabinose (N – 1) with varying arabinose pulse lengths and intervals;experimental results are represented by black dots.
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The multiple-inducer DIC three-counter
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synthetic counterscomplementary designs be used across a range of time scales
• RTC: as a safety mechanism (in biosensing, bioremediation, or medical purposes)
• Mul-indu-DIC : sequential events (in settings: developmental biology and gene cascades
• sin-indu- DIC : events encountered in its environment (e.g., for biosensing);
• SIMM design :in synthetic circuits to maintain genetic memory of low-frequency events
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Q&A
Figures all come from A. E. Friedland et al., Science 324, 1199 (2009)
Thank you!!