TetTag

The TetTag mouse is a bi-transgenic mutant used in neuroscience research that expresses a persistent marker (e.g. beta-galactosidase) under control of the immediate early gene fos.

This mouse strain allows the stable labeling of activated neurons in mice in a defined time window of several hours.

The second transgenic construct expresses a nuclear-localizing beta-galactosidase gene and the tetracycline regulated transactivator (tTA) under the control of the TetO tetracycline-responsive regulatory element.

[2] The TetTag mouse allows researchers to label activated neurons during a learning experiment (e.g. fear conditioning,[4] water maze training[5]).

[citation needed] The removal of doxycycline from the chow opens the window for activity-dependent labeling, but it takes several hours for the drug to be cleared from the brain.

TetTag mouse, molecular mechanism
Using the TetTag mouse for memory research. During fear conditioning, doxicycline is removed from the food to allow the interaction between tTA and the LacZ labeling system. Later memory retrieval activates another immediate early gene (Zif). In this example, two neurons carry the red and the nuclear green label, indicating that these neurons were active during memory storage (red) and again during retrieval (green). [ 1 ]