The game with the GFP receiver construct

Figure 1. Gameplay with GFP receiver construct after 11 hours

The receiver and sender colonies were plated in the honeycomb hexagonal pattern on LB-Agar for a timelapse experiment to follow the OHHL diffusion from sender cells to receiver cells.
The mine cells/sender cells are represented by an M, the numbers indicate how many mines surround the non mine colonies . The grey-scale makes it easy to identify 1,2 or 3 surrounding mines. As predicted in our model a gradient is visible in the colony. This gives the player information about the location of the mine. This should not happen in the Hydrolase set-up. The image is presented in inverted grey-scale for the best visibility.

The game with the hydrolases receiver construct

Figure 3. [OHHL] dependent information processing

1. Receiver cells respond to low OHHL levels: If one mine cell is close to a non-mine colony and by OHHL diffusion takes place to reach the non-mine colony. Due to a bandpass filter using the LuxR system in the non-mine colony,low concentrations of OHHL is detected which activates a reporter. Addition of the multi-substrate to this colony produces a salmon color and this indicates one mine is adjacent to the colony just played.

2. Receiver cells respond to high OHHL levels: If there are two or more mine colonies adjacent to a non-mine colony, a higher concentration of diffused OHHL will be processed by the receiver colony. The LuxR system works as a bandpass filter again and induces the expression of another reporter to show that 2 or more mines surround the selected colony. Addition of the nulti-substrate to this colony produces a magenta color that indicates more than two mines adjacent to this colony.

3. Receiver cells signal no mines in their vicinity. If there is no mine adjacent to a non-mine colony, no OHHL is processed. In this case, a constitutive hydrolase is expressed which on addition of the multi-substrate will give a yellow color. This indicates that there are no mines adjacent to this colony

The game play by the player

Figure 4: Gameplay

To play Colisweeper, the player has to pipette colorless substrates on a colony on the agar minefield. A single move of pipetting would require the player to choose between two colorless substrates. If the multi-susbtrate is added, this will reveal the identity of the colony- as in the number of mines surrounding a non-mine. The single colorless substrate is pipetted onto a colony if the player is certain of a mine colony. Addition of either substrates produces a defined colored product within minutes, allowing identification of the played colony and the number of mines surrounding it.

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