The Ceratitis capitata homologue of the Drosophila sex-determining gene sex-lethal is structurally conserved, but not sex-specifically regulated.
In Drosophila, Sxl functions as a binary switch in sex determination. Under the control of the primary sex-determining signal, it produces functional protein only in XX animals to implement female development. Here we report that, in contrast to Drosophila, the Sxl homologue in the Medfly, Ceratitis capitata, expresses the same mRNAs and protein isoforms in both XX and XY animals irrespective of the primary sex-determining signal. Also, experiments with two inducible transgenes demonstrate that the corresponding Ceratitis SXL product has no significant sex-transforming effects when expressed in Drosophila. Similar results have been obtained for the Sxl homologue of Musca domestica (Meise, M., Hilfiker-Kleiner, D., Brunner, C., DŁbendorfer, A., N¿thiger, R. and Bopp, D. (1998) Development 125, 1487-1494). Our findings suggest that Sxl acquired its master regulatory role in sex determination during evolution of the Acalyptratae group, most probably after phylogenetic divergence of the genus Drosophila from other genera of this group.
Saccone
G
G
Dipartimento di Genetica, Biologia generale e Moleculare, Universitá degli Studi di Napoli 'Federico II', Napoli, Italy. saccone@biol.dgbm.unina.it
Peluso
I
I
Artiaco
D
D
Giordano
E
E
Bopp
D
D
Polito
L C
LC
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001756:Blastoderm / Q000502:physiology; D017124:Conserved Sequence; D004175:Diptera / Q000196:embryology / Q000235:genetics*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000502:physiology; D019143:Evolution, Molecular; D005260:Female; D018507:Gene Expression Regulation, Developmental; D015723:Gene Library; D007301:Insect Hormones / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D016601:RNA-Binding Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012727:Sex Characteristics; D019849:Sex Determination Processes; D014158:Transcription, Genetic; D014960:X Chromosome; D014998:Y Chromosome
D029721:Drosophila Proteins; D007301:Insect Hormones; D016601:RNA-Binding Proteins; C067777:Sxl protein, Drosophila