Cells with only the T7 RNA polymerase plasmid, shown under UV light. There is no fluorescence.

Cells with both the T7 RNA polymerase plasmid and the flipped Hamiltonian Path Problem plasmid, shown under UV light. There is visible green fluorescence.

On the left, cells with the T7 RNA polymerase plasmid and a plasmid containing both split RFP and split GFP. These cells fluoresce a bright green under UV light and look pink under white light. On the right, cells with only the T7 RNA polymerase and split RFP.