合成生物學的目的在於以可替換的標準化元件模擬生物行為，及建構具有特定功能的新穎人工生物系統。在本篇研究中，我們運用了以基因演算法 (genetic algorithms, GA) 為基礎的搜尋方法，從充分特性化的啟動子 - 核糖體結合位元件庫中，有效地尋找適當元件，並在大腸桿菌內建構一套具有特定輸入/輸出響應，強健且可受外部調控的合成生物濾波器裝置。基因電路的閾值可受控制型誘導物的濃度調節。
綠螢光蛋白 (GFP) 在本實驗的基因電路中被用來做為報導蛋白，可使用酵素免疫分析儀 (ELISA reader) 偵測其表現量。我們證實了生物濾波器在生物體內的基因表現模式，對應輸入的化學物質濃度梯度分別展示出低通和高通的特性。在未來，我們可挑選不同具有相異動態活性的啟動子 - 核糖體結合位元件，精確調整輸入/輸出響應的閾值，使實驗結果更能吻合模型預測。生物濾波器可在發育生物學中的形式生成，生物感測器，以及治療癌症上提供相當廣泛的應用。

Synthetic biology aims both to employ standard interchangeable components to mimic biological behavior, and to construct novel artificial biological systems with prescribed functions. In this study, the GA-based searching method was used to efficiently select an adequate set of promoter-RBS components from the well-characterized promoter-RBS libraries, and robust externally tunable synthetic biological filter devices with a specified input/output (I/O) response were built in Escherichia coli. The thresholds of these gene circuits could be tuned by adjusting the concentration of the control inducer.
The green fluorescent protein (GFP) was employed as the reporter protein in the gene circuit, of which expression levels were measured using an ELISA reader. The gene expression patterns of these biological filters exhibited low-pass and high-pass like characteristics respectively in response to an input chemical gradient in vivo. In the future, different promoter-RBS components with different kinetic activities may be selected to precisely tune the threshold of the I/O response of filters, thereby making the experimental results more closely fit the model prediction. The biological filters may provide a wide variety of applications in pattern formation, biosensor, and cancer therapy.

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