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Abstract
Does God play dice with the cell?
Stochastic fluctuation in a cellular context and the lambda-phage
bifurcation have been extensively studied. However, from a bottom-up
synthetic aspect, we aim to exploit the cellular "noise" to build an
E. coli version of a computational device, the "Random Number
Generator". One random binary digit can be generated by capturing an
initial Polymerase binding event with a pair of mutually exclusive
promoters. Reciprocal inhibition using two repressors shall achieve
unilateral expression of the "switch", with fluorescence reporters
indicating the probability of each alternative occurrence.
Balancing the two sets of affinity and kinetic parameters and
maintaining a single copy of this synthetic device integrated into the
bacterial chromosome shall improve performance.
If successful, coupled with other reporters we envision multiple extensions of this
"Randomizer", including a Memorizer that utilizes a hierarchy of
XOR-calculations to "store" a multi-digit random number, and
intriguing pattern generation involving chemical gradients and random
"population behavior". In this case, the randomizer would work like a black box. As shown in the animation below, when there is an input as start, it would generate an output, either A or B randomly.
Meanwhile, the memorizer will remember the output of randomizer, until the next randomizer output comes.
So When randomizing events happen one after another, the XOR gate reporter could integrate the neighboring two outputs from randomizer( the former one is stored in memorizer), and fires if the two outputs are different.
- We are grateful to the generous sponsorship and support from the Lee Hysan Foundation.
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