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September 6, 2006

Drosophila Melanogaster Testi

Drosophila Melanogaster Testi

Two views of the apical region of one testis from an adult male Drosophila melanogaster are shown here. The bottom view shows the testis stained with DAPI (diamidino/phenylindole) to reveal DNA (blue fluorescence), while the top view is the same testis immunostained with an antibody against SXL protein (red fluorescence). SXL protein is the feminizing product of the master sex-determination gene of the fruit fly. A testes, being a male organ, normally would have none of this female-specific SXL protein, but in the testes shown here, the protein was artificially induced simply by increasing the dose of wildtype alleles of the SXL gene itself and some X-linked genes that regulate its expression.

One of the goals of this research was to learn how such ectopic expression of SXL would affect spermatogenesis and thereby discover how the response of germ cells and somatic cells in the organism to inappropriate SXL expression might differ. The figure shows that SXL female protein does disrupt male germ cell development somewhat (the persistence of a strong blue signal in the red cells  and only in the red cells  as one moves away from the apex, reflects a block in the differentiation of male germ cells that express SXL protein), but the effects are not nearly as drastic as they would be in somatic cells where sexual identity would be reversed and the process of X-chromosome dosage compensation would be disrupted. (Date of Image: 1997)

Credit: From Fig. 3 in J. H. Hager and T. W. Cline, Development 124:5033-5048 (1997)


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