| A simplified view of sex determination pathways in the
somatic gonad and
courtesy of Abbie Casper and Mark Van Doren. diagram © 2006 Casper and Van Doren, Johns Hopkins University
cells, the ratio of X chromosomes to autosomes (X:A)
activity of Sex-lethal (Sxl), which, in turn, activates
(tra). tra, along with transformer 2 (tra2), controls the alternative
RNA splicing of doublesex (dsx), which determines whether the
somatic gonad will develop as male or as female. In the germ cells, the
X:A ratio also influences sexual identity, and ovo, ovarian tumor
(otu) and Sxl
promote female germ cell development. Interactions
between germ cells and
somatic cells also influence germline sex
determination and act through
extracellular ligands, such as Unpaired
(Upd), which promotes male
development. Gap junctions (red) may also
facilitate communication between
the two cell types.
Reference: Casper, A. and Van Doren, M. (2006). The control of sexual identity in the Drosophila germline. Development 133(15): 2783-91. Full text of article
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