Overview

Why E.calculus ?

During our brainstorming meetings to decide our iGEM project many ideas about building artificial regulations came out. We realized that for most of these systems, various arithmetic operations exist in cellular systems but are highly specific and certainly not prone to do real mathematical operations. We therefore decided to create a n-bit bacterial full adder which could be operated by the user and able to transmit a carry if needed. Considering that some of the previous iGEM projects tackled the bacterial adder concept, we envisioned using a new strategy that has several advantages: recombination based logic gates. The most important goals and achievments would be to demonstrate that recombination-based switches represent simple yet highly efficient genetic logic gates modules that can be further integrated into more complex genetic devices. Besides the full adder idea, these genetic devices should lead to substantial progresses in the design of artificially regulated synthetic pathways.

From TI83+ to E. calculus

An electronic full-adder consists of the association of 5 logic gates (2 XOR gates, 2 AND gates, and 1 OR gate) which are able to receive 3 input signals (2 input bits and the last stage carry) and give the right answer to the user. (View "Full Adder" Part)

With E. calculus, we also tried to link the gate genetic devices to a semi-artificial input system that uses blue and red light as the input bits(View "Input" Part), and a diffusive molecule, acyl homoserine lactone (AHL) for the carry (View "Carry" Part) . We also wanted that the results of the various operations could be easily readable by experimentators. We then chose a clearly visible output pigment: the Red Fluorescent Protein (RFP) (View "Output" Part), visible by human eyes, even at a low concentration.