Figure 4. Tetracycline-repressible lethal systems.

Figure 4

Tetracycline-repressible lethal systems. A,B) Two-component system. tTA is placed under the control of a suitable promoter, e.g., constitutive, female-specific or embryo-specific. A) In the absence of tetracycline (Tc) tTA binds tetO, drives expression of an effector molecule leading, in the case of a lethal effector, to death. B) In the presence of Tc, tTA binds Tc; the Tc-bound form of tTA does not bind DNA, it therefore does not activate expression of the effector and the system is inactivated. C,D) Simplified one-component system. C) In the absence of Tc, basal expression of tTA leads to the synthesis of more tTA, which accumulates to high level. This level can be regulated by modifying the stability and translational efficiency of the tTA mRNA. At the highest levels, expression is lethal, so tTA is both the driver and the effector. D) In the presence of Tc, tTA is inactivated by Tc and is therefore expressed only at basal levels. (Adapted from ref. 48).

From: Insect Population Suppression Using Engineered Insects

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