Figure 6
Model for sex determination in T. castaneum.
Maternally transferred TcTra is translated to make TcTra protein only in females. This TcTra protein splices the zygotically transcribed TcTra pre-mRNA into female mode in turn production of TcTra protein. Continuous production of TcTra, in females, is ensured by the positive autoregulatory feedback loop. TcTra splices the Tcdsx pre-mRNA to produce three female-specific isoforms (Tcdsxf1, Tcdsxf2 and Tcdsxf3). Also, TcTra inhibits some of the Dosage compensation components (DCC) to prevent the formation of active dosage compensation complex, in females. In males, an unknown dominant factor (M) inhibits the translation of maternally supplied Tctra transcript and/or degrades the maternal transcripts or inhibits its autoregulation. The lack of initial TcTra protein, in males, leads to the default splicing of Tctra, coding for truncated non-functional protein. In the absence of TcTra protein Tcdsx pre-mRNA splices in a male mode producing Tcdsxm. Absence of TcTra protein in males allows the formation of functional dosage compensation complex owing to the presence of all the DCC components (dark blue). Dark color represents active protein whereas corresponding light color represents truncated or inactive protein.
