Drosophila melanogaster male somatic cells feminized solely by TraF can collaborate with female germ cells to make functional eggs.
Female differentiation of Drosophila germ cells is induced by cell-nonautonomous signals generated in the gonadal soma that work with germ-cell-autonomous signals determined by germ-cell X chromosome dose. Generation of the nonautonomous feminizing signals was known to involve female-specific protein encoded by the master sex-determination gene Sex-lethal (Sxl) acting on its switch-gene target transformer (tra) to produce Tra(F) protein. However, it was not known whether Sxl's action on tra alone would suffice to trigger a fully feminizing nonautonomous signal. We developed a constitutively feminizing tra transgene that allowed us to answer this question. In gynanders (XX//XO mosaics) feminized by this Tra(F) transgene, functionally Sxl- haplo-X (chromosomally male) somatic cells collaborated successfully with diplo-X (chromosomally female) germ cells to make functional eggs. The fertility of such gynanders shows not only that Tra(F) is sufficient to elicit a fully feminizing nonautonomous signal, but also that haplo-X somatic cells can execute all other somatic functions required for oogenesis, despite the fact that their genome is not expected to be dosage compensated for such diplo-X-specific functions. The unexpected observation that some Tra(F)-feminized gynanders failed to lay their eggs showed there to be diplo-X cells outside the gonad for which Tra(F)-feminized haplo-X cells cannot substitute.
Evans
Daniel S
DS
Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204, USA.
Cline
Thomas W
TW
D000818:Animals; D002875:Chromosomes; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology*; D005260:Female; D005262:Feminization; D005298:Fertility; D005838:Genotype; D005854:Germ Cells / Q000166:cytology*; D006066:Gonads / Q000166:cytology; D006238:Haploidy; D008297:Male; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009866:Oogenesis; D010063:Ovum / Q000166:cytology*; D016601:RNA-Binding Proteins / Q000378:metabolism; D019076:Transgenes
D029721:Drosophila Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; C067777:Sxl protein, Drosophila; C097162:Tra protein, Drosophila