A repressible female-specific lethal genetic system for making transgenic insect strains suitable for a sterile-release program

Abstract

We have developed a tetracycline-repressible female-specific lethal genetic system in the vinegar fly Drosophila melanogaster. One component of the system is the tetracycline-controlled transactivator gene under the control of the fat body and female-specific transcription enhancer from the yolk protein 1 gene. The other component consists of the proapoptotic gene hid under the control of a tetracycline-responsive element. Males and females of a strain carrying both components are viable on medium supplemented with tetracycline, but only males survive on normal medium. A strain with such properties would be ideal for a sterile-insect release program, which is most effective when only males are released in the field.

Figure 1

The tetracycline-regulated female-killing system. Expression of tTA is controlled with the female- and fat-body-specific transcription enhancer from the yp1 gene (18). In the absence of tetracycline, tTA binds to tetO and induces expression of the proapoptotic gene hid. The loss of fat body results in female-specific lethality. In the presence of tetracycline, females are fully viable, because the binding of tTA to tetO is inhibited, switching off hid expression.

Figure 2

Expression of tTA is confined to the female fat body and is inhibited by tetracycline. Climbing third instar larvae were sexed, dissected, and stained for β-galactosidase expression (25). Strong staining was seen in fat body of female larvae raised on normal medium (A) but not medium that contained tetracycline (10 μg/ml; B). Little staining above background level was seen in fat body from male larvae raised on either normal medium (C) or medium supplemented with tetracycline (D).