Team:Davidson-MissouriW/CreLox
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<h1>Knapsack Construct Models</h1> | <h1>Knapsack Construct Models</h1> | ||
- | We designed five different construct models that could potentially lead us to a biological solution to the knapsack problem. These constructs include various lox sites, a reporter fluorescent protein, and a TetA gene that has an upper and lower threshold of expression in order to survive, thus providing a means to find "objects" (subset of modules) with the correct "weight" (expression of TetA).</p> | + | We designed five different construct models that could potentially lead us to a biological solution to the knapsack problem. These constructs include various lox sites, a reporter fluorescent protein, and a TetA gene that has an upper and lower threshold of expression in order to survive, thus providing a means to find "objects" (subset of modules) with the correct "weight" (expression of TetA).<br><br> |
- | + | To determine which model would be best to solve the knapsack problems, we analyzed each version and its theoretical probabilities for different results that could be left after any number cre interactions. Furthermore, we created the construct simulator that can calculate for us the theoretical probabilities of the possible results after any number of cre steps for our construct and any custom construct. From this tool and an analysis of the possible results provided by the tool, we have decided that version D is the model to solve the knapsack problem.</p> | |
<center><h3>Version A: Allows inversion and excision within and over multiple modules.</h3></center> | <center><h3>Version A: Allows inversion and excision within and over multiple modules.</h3></center> | ||
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Latest revision as of 04:29, 26 October 2010
Characterizing Cre/lox Recombination Method
Mechanism behind Cre/lox Recombination
The Cre-lox tool is a site-specific recombination system that is widely used in biological research to manipulate DNA. It was discovered in the early 90's through characterization of coliphage P1 recombination system. The Cre recombinase enzyme, a 38kDa protein, catalyzes the recombination of DNA between two lox sites. These lox sites, each 34 bp long, consist of two inverted repeat arms flanking a spacer region of 8bp that is unique to the lox site.
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Designing Lox Sites
In order to randomly "select objects" for the knapsack problem, we used the Cre-lox recombination method of excision and inversion. We needed a set of variant lox sites in order to create constructs that would yield different subsets of survival and fluorescence to optimally fill the knapsack. These variant lox sites have mutations specific to the 8bp spacer region and do not recombine. We created 10 new lox sites with mutations in the 8 bp region: loxN Forward and Reverse, loxm2 Forward and Reverse, lox2272 Forward and Reverse, lox5171 Forward and Reverse, and loxBri Forward and Reverse. In addition, we added the wildtype loxP Reverse to the registry.
We floxed red fluorescent protein with these variant lox sites using 16 out of the 21 combinations of the 5 lox forward variants to see immediately if recombination occurred in the presence of Cre. These constructs below follow a moderate promoter, pTet. The key for the constructs is above and colors refer to specific lox sites.
Would you like a bagel with all that lox?
Knapsack Construct Models
We designed five different construct models that could potentially lead us to a biological solution to the knapsack problem. These constructs include various lox sites, a reporter fluorescent protein, and a TetA gene that has an upper and lower threshold of expression in order to survive, thus providing a means to find "objects" (subset of modules) with the correct "weight" (expression of TetA).To determine which model would be best to solve the knapsack problems, we analyzed each version and its theoretical probabilities for different results that could be left after any number cre interactions. Furthermore, we created the construct simulator that can calculate for us the theoretical probabilities of the possible results after any number of cre steps for our construct and any custom construct. From this tool and an analysis of the possible results provided by the tool, we have decided that version D is the model to solve the knapsack problem.