Figure 1.

The OX3097 transposon and induced phenotypes in olive fly. (A) Diagrammatic representation of the OX3097 transposon. OX3097 comprises a fluorescent marker (hr5-IE1-DsRed2), and the female-specific tTAV expression system (tetO-Dmhsp70 minimal promoter - Cctra:tTAV) [15]. Sex-specific alternative splicing of the Cctra intron leads to production of tTAV and the initiation of a lethal tTAV positive-feedback loop in females only [14,15,34]. (b) Products of alternative splicing of Cctra:tTAV in (lane 1) male and (lane 2) female OX3097D-Bol olive flies. Three splice variants were detected, corresponding to Cctra transcripts M1, M2 and F1 [18] (identity confirmed by sequencing). Only females produce the F1 splice variant, corresponding to the reconstitution of the tTAV open reading frame and leading to production of functional tTAV. Lane M shows DNA size standards: 200-1,000 bp in 200-bp increments (Eurogentec Smartladder). (C) Penetrance and (D) tetracycline repressibility of female lethality in five OX3097 olive fly lines. Strains OX3097A-D-Bol &F-Bol are five insertion lines of OX3097 in olive fly. Penetrance and repressibility of female-specific lethality was assessed by crossing heterozygous males of each strain to virgin wild-type (WT) females, and collecting eggs on filter paper saturated with water containing either 0 μg/ml tetracycline or 100 μg/ml tetracycline. The sex ratio of adult progeny expressing the DsRed2 fluorescent marker is shown for each strain compared with wild-type (WT) progeny. Lines A, C and D showed fully penetrant female-specific lethality when reared in the absence of tetracycline (off-tet); that is, they produced no female progeny off-tet in this assay. In lines C and D, female-specific lethality was also efficiently repressed on-tet. (E) Fluorescence microscopy allows discrimination of OX3097D-Bol from wild type at larval, pupal, and adult stages. Photomicrographs of OX3097D-Bol and wild-type olive flies under (upper panels) fluorescence and (lower panels) bright-field illumination. Each panel shows OX3097D-Bol to the left and wild-type to the right: OX3097D-Bol and wild-type (1,2) larvae, (3,4) pupae, and (5,6) adults are shown. Expression of DsRed2 is clearly visible all over the OX3097D-Bol larvae and pupae, and in areas of less opaque cuticle (for example, the labellum, upper thorax, leg joints, and anus) of OX3097D-Bol adults.

Ant et al. BMC Biology 2012 10:51   doi:10.1186/1741-7007-10-51
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