Proteomic analysis of the phenotype of the scaleless wings mutant in the silkworm, Bombyx mori.

A scaleless wing mutant of silkworm, Bombyx mori, has much fewer scales than wild type (WT). The scaleless phenotype was associated with tracheal system developmental deficiency and excessive apoptosis of scale cells. In this study, the wing discs proteins of WT and scaleless during pupation were studied using 2-DE and mass spectrometry. Of the 99 identified protein spots, four critical differentially expressed proteins between WT and scaleless were further verified using Q-PCR. At the first day of pupation (P0) in WT, imaginal disk growth factor (IDGF) was upregulated, whereas actin-depolymerizing factor 1 (ADF1) and profilin (PFN), which associated with cellular motility and cytoplasmic extension, were downregulated. We speculated their coaction counteracts the correct organization of the tracheal system in wing disc. Thiol peroxiredoxin (TPx) was upregulated in scaleless at P0, but its mRNA higher expression occurred in the day before pupation (S4). TPx could inhibit the formation of hydrogen peroxide, preventing the release of cytochrome C and activation of the caspase family protease. Its higher expression in scaleless was responsible for the apoptosis of scale cells delayed. The results provide further evidence that the scaleless phenotype was related to the tracheal system developmental deficiency and excessive apoptosis of scale cells.