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First, we define the Receptor as the vector that has already existed in the cell (E.coli.), and the  Donor as the vector containing the desired gene that we intend to integrate  into the Receptor. The gene circuits for these plasmids are illustrated below. When the Donor vector carrying the gene of interest GENE1 was introduced to the E Coli which contains  the Receptor vector, the site-specific recombination will occur between the attB1 site and the attP1 site, so that the two sequences will be integrated into one circular DNA. The recombinant DNA then could be selected in the liquid culture containing both ampicillin and  kanamycin. Then, under inducible conditions, Cre will be expressed and the recombined sequence will be divided into two separate plasmids; one will retain  the desired gene 1, while the other will preserve the killer gene ccdB, which  is under the control of another inducible promoter. Because the two plasmids have shared origin site, plasmid incompatibility will occur thus the two kinds  of plasmids will be separated into different cells. When induced, the expressed CCDB will lead to the Programed Cell Death (PCD). In order to realize the linkage of GENE 1 with GENE 2, we will introduce the new plasmid containing  the desired GENE2 to the survival cells, in which the plasmids containing GENE  1 will behave as the new Receptor plasmid. Very similarly recombination between the attB2 and attP2 and the cleavage between the two loxp sites will be  performed, and plasmids containing the linked GENE1 and GENE2 will be selected  when the promoter expresses CCDB is induced. The reason for us to use two sets of attB/attP specific  sites is to avoid the combination within one module. <td colspan="2" bgcolor="#0000FF"> a           <td width="528" height="41" bgcolor="#03438A" class="sidebarHeader STYLE5 STYLE4 STYLE12">Our Design <td height="821" valign="top" bgcolor="#03438A" class="bodyText STYLE5 STYLE4 STYLE10"> The design for the cell 1: The genetic circuit can be divided into three different functional sections. The first one in the graph is the detecting Section. By using this section you can detect the cell density according to the intensity of the red fluorescence. The detecting section is especially useful when you incubate two different kinds of E.coli in a coculture. The second one is the Helper section. We call it helper section because the LuxR protein is the prerequisite for the activation of  PLux. Here we used a constitutive promoter to regulate the expression of the LuxR protein. The core section is the convertible switch. Convertible switch is a genetic device that can switch between two convertible states, which,  here, represents a different survival strategy for the cells each. When adding Arabinose/AHL different genes will get expressed behind the two mutually-repressive promoters. That means when added into the culture, AHL will diffuse into the cell bind the LuxR protein and form  a complex which can activate the LuxPr promoter and then the genes of rhII capR  and araC will express. Then the AraC protein will bind to the PBad/araC promoter and repress the expression of the aiiA and another capR gene. However, you can turn the switch to the other side by adding Arobinose. When adding Arobinose into the culture, the repression functional molecular AraC protein  will get released from the PBad/AraC promoter. With the expression of the aiiA gene the signal molecular will get digested and therefore decrease to a proper  level which is not high enough to activate the LuxPr promoter. The most important thing in this section is the capacity of the two different promoters luxPr and PBad/araC are quite different. When the luxRr promoter is activated, its higher capacity will express more chloromycetin resistant protein and another important thing is by sensing the AHL which is  sent out by cell 2 it can produce another kind of signal molecular BHL. Cell 2 is similarly designed as Cell 1 This idea was inspired by the theory of Prisoner’s Dilemma. As in prisoners’ dilemma, the bacteria in our design are faced with two solutions for coexistence, they could either  choose to cooperate with each other by providing inducers to express their  partners’ antibiotics-resistance genes or they could take a foe strategy in  which no cooperation is needed for both strains’ survival. <td colspan="2" bgcolor="#03438A">