A regulatory model for the formation of sexually dimorphic horns in T. dichotomus.

In males, default splicing generates Tdic-dsxM, whereas in females, Tdic-tra (a female isoform, traF) and Tdic-tra2, generates Tdic-dsxF by female-specific splicing of Tdic-dsx pre-mRNA. Prepupal Tdic-dsxM expression in males positively regulates the growth of head and thoracic horn primordia, whereas prepupal Tdic-dsxF in females suppresses the horn growth activity. In pupa, Tdic-dsxM regulates thoracic horn remodeling, but is dispensable for remodeling of head horn. GRN, gene regulatory network.