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Sex and the single cell. II. There is a time and place for sex.

Robinett CC, Vaughan AG, Knapp JM, Baker BS - PLoS Biol. (2010)

Bottom Line: Evolutionary considerations suggest such a mosaic expression of sexuality is likely to be a property of other animal species having two sexes.These results have also led to a major revision of our view of how sex-specific functions are regulated by the sex hierarchy in flies.Thus tissue-specific aspects of sexual development are jointly specified by post-transcriptional control by Sxl and by the transcriptional controls of dsx and fru expression.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Stanford University, Stanford, California, United States of America.

ABSTRACT
The Drosophila melanogaster sex hierarchy controls sexual differentiation of somatic cells via the activities of the terminal genes in the hierarchy, doublesex (dsx) and fruitless (fru). We have targeted an insertion of GAL4 into the dsx gene, allowing us to visualize dsx-expressing cells in both sexes. Developmentally and as adults, we find that both XX and XY individuals are fine mosaics of cells and tissues that express dsx and/or fruitless (fru(M)), and hence have the potential to sexually differentiate, and those that don't. Evolutionary considerations suggest such a mosaic expression of sexuality is likely to be a property of other animal species having two sexes. These results have also led to a major revision of our view of how sex-specific functions are regulated by the sex hierarchy in flies. Rather than there being a single regulatory event that governs the activities of all downstream sex determination regulatory genes-turning on Sex lethal (Sxl) RNA splicing activity in females while leaving it turned off in males-there are, in addition, elaborate temporal and spatial transcriptional controls on the expression of the terminal regulatory genes, dsx and fru. Thus tissue-specific aspects of sexual development are jointly specified by post-transcriptional control by Sxl and by the transcriptional controls of dsx and fru expression.

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dsxGAL4 driving UAS-induced fluorescent reporters recapitulates known patterns of gonadal dsx expression.(A) dsxGAL4 expression is restricted to cells of the paired uncoalesced gonads in embryonic stage 13. The embryo posterior is marked by an asterisk, and native GFP fluorescence was imaged from the membrane reporter, UAS-mCD8::GFP. Scale bar, 100 µm. (B–C) Expression of dsxGAL4 in the male third instar larval gonad is restricted to somatic cells. Reporter is UAS-RedStinger (nuclear DsRed). (Bi) dsxGAL4-expressing cells include the clustered hub cells of the stem cell niche at the gonad apical tip (arrow), cyst cells dispersed throughout the gonad (barbed arrowhead), and terminal epithelial cells with small round nuclei at the basal end of the gonad (asterisk). A fat body cell nucleus is indicated (arrowhead). (Bii) dsxGAL4 expression (magenta) is excluded from the germline cells marked with cytoplasmic VASA (green). Scale bar, 50 µm. (C) Expression of the JFRC-IVSA membrane-bound GFP reporter (green) reveals sheath cell cytoplasmic processes ramifying through cysts of male germ cells in the basal half of the gonad. DNA of the large male germline cells is stained with DAPI (magenta). Gonad posterior indicated with an asterisk. Single confocal section shown. Scale bar, 20 µm. (D) dsxGAL4 expression in the female third instar larval gonad is restricted to somatic cells (magenta) and is excluded from the germline cells marked with cytoplasmic VASA (green). A fat body cell nucleus is indicated (arrowhead). Reporter is UAS-RedStinger (nuclear DsRed). Scale bar, 50 µm. (E) dsxGAL4 expression in hub cells of the stem cell niche at the apical tip of male the gonad was visualized with the JFRC-IVSA membrane-bound GFP reporter (Eii; green in Eiv). Processes of dsxGAL4-expressing cells enveloped germline cells marked with VASA (Ei; blue in Eiv), including the ring of germline stem cells adjacent to the hub (arrows). Expression in hub cells is confirmed by overlap with DN-Cadherin (DN-Cad) (Eiii; red in Eiv), which marks membranes of the hub cells (arrowheads). Overlap of membrane-bound GFP with DN-Cadherin is yellow in the merge (Eiv). Scale bar, 50 µm.
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pbio-1000365-g002: dsxGAL4 driving UAS-induced fluorescent reporters recapitulates known patterns of gonadal dsx expression.(A) dsxGAL4 expression is restricted to cells of the paired uncoalesced gonads in embryonic stage 13. The embryo posterior is marked by an asterisk, and native GFP fluorescence was imaged from the membrane reporter, UAS-mCD8::GFP. Scale bar, 100 µm. (B–C) Expression of dsxGAL4 in the male third instar larval gonad is restricted to somatic cells. Reporter is UAS-RedStinger (nuclear DsRed). (Bi) dsxGAL4-expressing cells include the clustered hub cells of the stem cell niche at the gonad apical tip (arrow), cyst cells dispersed throughout the gonad (barbed arrowhead), and terminal epithelial cells with small round nuclei at the basal end of the gonad (asterisk). A fat body cell nucleus is indicated (arrowhead). (Bii) dsxGAL4 expression (magenta) is excluded from the germline cells marked with cytoplasmic VASA (green). Scale bar, 50 µm. (C) Expression of the JFRC-IVSA membrane-bound GFP reporter (green) reveals sheath cell cytoplasmic processes ramifying through cysts of male germ cells in the basal half of the gonad. DNA of the large male germline cells is stained with DAPI (magenta). Gonad posterior indicated with an asterisk. Single confocal section shown. Scale bar, 20 µm. (D) dsxGAL4 expression in the female third instar larval gonad is restricted to somatic cells (magenta) and is excluded from the germline cells marked with cytoplasmic VASA (green). A fat body cell nucleus is indicated (arrowhead). Reporter is UAS-RedStinger (nuclear DsRed). Scale bar, 50 µm. (E) dsxGAL4 expression in hub cells of the stem cell niche at the apical tip of male the gonad was visualized with the JFRC-IVSA membrane-bound GFP reporter (Eii; green in Eiv). Processes of dsxGAL4-expressing cells enveloped germline cells marked with VASA (Ei; blue in Eiv), including the ring of germline stem cells adjacent to the hub (arrows). Expression in hub cells is confirmed by overlap with DN-Cadherin (DN-Cad) (Eiii; red in Eiv), which marks membranes of the hub cells (arrowheads). Overlap of membrane-bound GFP with DN-Cadherin is yellow in the merge (Eiv). Scale bar, 50 µm.

Mentions: dsx transcripts and DSXM protein are only detected in cells of the developing gonads in stage 13–17 embryos (www.fruitfly.org/cgi-bin/ex/insitu.pl) [23],[27], and we saw dsxGAL4 driven UAS-mCD8::GFP [30] expression that precisely recapitulated this expression pattern (Figure 2A). This pattern of reporter gene expression was completely dependent on the presence of dsxGAL4, as were all other patterns of dsxGAL4 expression described below.


Sex and the single cell. II. There is a time and place for sex.

Robinett CC, Vaughan AG, Knapp JM, Baker BS - PLoS Biol. (2010)

dsxGAL4 driving UAS-induced fluorescent reporters recapitulates known patterns of gonadal dsx expression.(A) dsxGAL4 expression is restricted to cells of the paired uncoalesced gonads in embryonic stage 13. The embryo posterior is marked by an asterisk, and native GFP fluorescence was imaged from the membrane reporter, UAS-mCD8::GFP. Scale bar, 100 µm. (B–C) Expression of dsxGAL4 in the male third instar larval gonad is restricted to somatic cells. Reporter is UAS-RedStinger (nuclear DsRed). (Bi) dsxGAL4-expressing cells include the clustered hub cells of the stem cell niche at the gonad apical tip (arrow), cyst cells dispersed throughout the gonad (barbed arrowhead), and terminal epithelial cells with small round nuclei at the basal end of the gonad (asterisk). A fat body cell nucleus is indicated (arrowhead). (Bii) dsxGAL4 expression (magenta) is excluded from the germline cells marked with cytoplasmic VASA (green). Scale bar, 50 µm. (C) Expression of the JFRC-IVSA membrane-bound GFP reporter (green) reveals sheath cell cytoplasmic processes ramifying through cysts of male germ cells in the basal half of the gonad. DNA of the large male germline cells is stained with DAPI (magenta). Gonad posterior indicated with an asterisk. Single confocal section shown. Scale bar, 20 µm. (D) dsxGAL4 expression in the female third instar larval gonad is restricted to somatic cells (magenta) and is excluded from the germline cells marked with cytoplasmic VASA (green). A fat body cell nucleus is indicated (arrowhead). Reporter is UAS-RedStinger (nuclear DsRed). Scale bar, 50 µm. (E) dsxGAL4 expression in hub cells of the stem cell niche at the apical tip of male the gonad was visualized with the JFRC-IVSA membrane-bound GFP reporter (Eii; green in Eiv). Processes of dsxGAL4-expressing cells enveloped germline cells marked with VASA (Ei; blue in Eiv), including the ring of germline stem cells adjacent to the hub (arrows). Expression in hub cells is confirmed by overlap with DN-Cadherin (DN-Cad) (Eiii; red in Eiv), which marks membranes of the hub cells (arrowheads). Overlap of membrane-bound GFP with DN-Cadherin is yellow in the merge (Eiv). Scale bar, 50 µm.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2864297&req=5

pbio-1000365-g002: dsxGAL4 driving UAS-induced fluorescent reporters recapitulates known patterns of gonadal dsx expression.(A) dsxGAL4 expression is restricted to cells of the paired uncoalesced gonads in embryonic stage 13. The embryo posterior is marked by an asterisk, and native GFP fluorescence was imaged from the membrane reporter, UAS-mCD8::GFP. Scale bar, 100 µm. (B–C) Expression of dsxGAL4 in the male third instar larval gonad is restricted to somatic cells. Reporter is UAS-RedStinger (nuclear DsRed). (Bi) dsxGAL4-expressing cells include the clustered hub cells of the stem cell niche at the gonad apical tip (arrow), cyst cells dispersed throughout the gonad (barbed arrowhead), and terminal epithelial cells with small round nuclei at the basal end of the gonad (asterisk). A fat body cell nucleus is indicated (arrowhead). (Bii) dsxGAL4 expression (magenta) is excluded from the germline cells marked with cytoplasmic VASA (green). Scale bar, 50 µm. (C) Expression of the JFRC-IVSA membrane-bound GFP reporter (green) reveals sheath cell cytoplasmic processes ramifying through cysts of male germ cells in the basal half of the gonad. DNA of the large male germline cells is stained with DAPI (magenta). Gonad posterior indicated with an asterisk. Single confocal section shown. Scale bar, 20 µm. (D) dsxGAL4 expression in the female third instar larval gonad is restricted to somatic cells (magenta) and is excluded from the germline cells marked with cytoplasmic VASA (green). A fat body cell nucleus is indicated (arrowhead). Reporter is UAS-RedStinger (nuclear DsRed). Scale bar, 50 µm. (E) dsxGAL4 expression in hub cells of the stem cell niche at the apical tip of male the gonad was visualized with the JFRC-IVSA membrane-bound GFP reporter (Eii; green in Eiv). Processes of dsxGAL4-expressing cells enveloped germline cells marked with VASA (Ei; blue in Eiv), including the ring of germline stem cells adjacent to the hub (arrows). Expression in hub cells is confirmed by overlap with DN-Cadherin (DN-Cad) (Eiii; red in Eiv), which marks membranes of the hub cells (arrowheads). Overlap of membrane-bound GFP with DN-Cadherin is yellow in the merge (Eiv). Scale bar, 50 µm.
Mentions: dsx transcripts and DSXM protein are only detected in cells of the developing gonads in stage 13–17 embryos (www.fruitfly.org/cgi-bin/ex/insitu.pl) [23],[27], and we saw dsxGAL4 driven UAS-mCD8::GFP [30] expression that precisely recapitulated this expression pattern (Figure 2A). This pattern of reporter gene expression was completely dependent on the presence of dsxGAL4, as were all other patterns of dsxGAL4 expression described below.

Bottom Line: Evolutionary considerations suggest such a mosaic expression of sexuality is likely to be a property of other animal species having two sexes.These results have also led to a major revision of our view of how sex-specific functions are regulated by the sex hierarchy in flies.Thus tissue-specific aspects of sexual development are jointly specified by post-transcriptional control by Sxl and by the transcriptional controls of dsx and fru expression.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Stanford University, Stanford, California, United States of America.

ABSTRACT
The Drosophila melanogaster sex hierarchy controls sexual differentiation of somatic cells via the activities of the terminal genes in the hierarchy, doublesex (dsx) and fruitless (fru). We have targeted an insertion of GAL4 into the dsx gene, allowing us to visualize dsx-expressing cells in both sexes. Developmentally and as adults, we find that both XX and XY individuals are fine mosaics of cells and tissues that express dsx and/or fruitless (fru(M)), and hence have the potential to sexually differentiate, and those that don't. Evolutionary considerations suggest such a mosaic expression of sexuality is likely to be a property of other animal species having two sexes. These results have also led to a major revision of our view of how sex-specific functions are regulated by the sex hierarchy in flies. Rather than there being a single regulatory event that governs the activities of all downstream sex determination regulatory genes-turning on Sex lethal (Sxl) RNA splicing activity in females while leaving it turned off in males-there are, in addition, elaborate temporal and spatial transcriptional controls on the expression of the terminal regulatory genes, dsx and fru. Thus tissue-specific aspects of sexual development are jointly specified by post-transcriptional control by Sxl and by the transcriptional controls of dsx and fru expression.

Show MeSH
Related in: MedlinePlus