IGEM:Hong Kong HKUST/June 20

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General Info

From 6pm. to 8:45pm.

Rm 5486

Attendance: Xiuye, Jingjing, Cotton, Qing, Carmen, Jinyu, Guangnan, and Winnie.



by Guangnan

  • step1: Randomizer--Generate random no. by applying cI and cI434 model and changing binding affinity of promoter
    • The out put can be AD 1 or AD 2. They may adjacent to regulatory factor gene or have another promoter, which can be repressed by the regulatory factor and is constitutively turned on.
  • step2: Memorizer--Bi-stable switch: BD 1 and BD 2, their promoters are constitutively turned on and BD 1 and BD 2 can repress each other's promoter.
    • AD 1 or AD 2 can inhibit the repression of BD 1 and 2 on each other.
  • step3: Report--There are two identical promoter and can be activated by AD1 and BD1 or AD2 and BD2. (similar to Yeast two hybrid system) That is, if both AD1 and BD1 exist, then the final signal (can be GFP) can be expressed.

Memorizer is used to memorize the recent state of outcome from step1.

  • Problems: initial state of BD 1 and BD 2 is turned on, so their original level might be very high and can affect the first readout.


  1. CDE(Stripe) Pattern - by Jingjing
  2. Taichi Pattern - by Xiuye
  3. Digital Display - by Jingjing

In electical digital display, there are seven positions and 4 signals to fit 0 to 9. In our system, we can use 7 different kinds of E.coli to mimic those 7 positions and 2 signals x and y to fit 0 to 3.


by Cotton

E.coli can be induced to swim back and forth by applying 2 gradients (C & D) and 2 inducers (A & B). It firstly swims in one direction along one gradient (can be chemtoxic) and then when it meets B, it switches to sense another gradient so that it can swim back to original position. When it returns, that is, meets A, it switches to sense first gradient.

by Xiuye

  • swim and swam: different
  • E.coli can either rotate or swim. If it rotates clockwisely, it can rotate well and stay there. If it rotates anti-clockwisely, it cannot rotate well and then stop rotation and keep on swimming. We can apply this to detect its sensing of gradient. If it swims to a higher gradient of a molecule it likes, it will keep rotating. If it swims to a state it doesn't like, it may not rotate well and leave.


by Jingjing

  1. a simple circuit: z activates x and inhibits y, x and y can inhibit each other. so if y is dorminant in initial state, when z is put in, y will be switched to x.
  1. fim: when fim is put in, the promoter will change its direction.