Team:BrownTwo/Limiter/intro

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==''The Utility of Threshold Regulation''==
==''The Utility of Threshold Regulation''==
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[[Image:thresh.png|center|thumb|500px|An Electronic Limiter]]
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[[Image:thresh.png|right|thumb|300px|Threshold limitation]]
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<p>In the early days of radio, AM transmitters were vulnerable to overload by an input signal of too great a magnitude.  To protect the transmitter from damage, a limiter circuit was employed to attenuate signal peaks while allowing all subthreshold signal to pass through unchanged.  We have designed a genetic circuit that behaves similarly.  Our gene network reacts to the level of transcription of a gene of interest, limiting it to levels above or below a user-defined threshold.  In our proof-of-concept, we use synthetic transcription factors to limit the expression of an inducible reporter.  In practice, these modular transcription factors can be used to regulate any endogenous gene with a known promoter and transcription factor DNA-binding domain.  Extremes of gene expression can damage living systems, while normal expression is healthy.  Our limiter could react to the level of a gene's expression within individual cells, correcting problems only where and when they occur.</p>
<p>In the early days of radio, AM transmitters were vulnerable to overload by an input signal of too great a magnitude.  To protect the transmitter from damage, a limiter circuit was employed to attenuate signal peaks while allowing all subthreshold signal to pass through unchanged.  We have designed a genetic circuit that behaves similarly.  Our gene network reacts to the level of transcription of a gene of interest, limiting it to levels above or below a user-defined threshold.  In our proof-of-concept, we use synthetic transcription factors to limit the expression of an inducible reporter.  In practice, these modular transcription factors can be used to regulate any endogenous gene with a known promoter and transcription factor DNA-binding domain.  Extremes of gene expression can damage living systems, while normal expression is healthy.  Our limiter could react to the level of a gene's expression within individual cells, correcting problems only where and when they occur.</p>
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[[Image:Limiter_history.jpg|center|thumb|500px|An Electronic Limiter]]
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[[Image:Limiter_history.jpg|center|thumb|450px|An Electronic Limiter Circuit]]

Revision as of 13:01, 29 October 2008



The Utility of Threshold Regulation


Threshold limitation

In the early days of radio, AM transmitters were vulnerable to overload by an input signal of too great a magnitude. To protect the transmitter from damage, a limiter circuit was employed to attenuate signal peaks while allowing all subthreshold signal to pass through unchanged. We have designed a genetic circuit that behaves similarly. Our gene network reacts to the level of transcription of a gene of interest, limiting it to levels above or below a user-defined threshold. In our proof-of-concept, we use synthetic transcription factors to limit the expression of an inducible reporter. In practice, these modular transcription factors can be used to regulate any endogenous gene with a known promoter and transcription factor DNA-binding domain. Extremes of gene expression can damage living systems, while normal expression is healthy. Our limiter could react to the level of a gene's expression within individual cells, correcting problems only where and when they occur.



An Electronic Limiter Circuit