Fig. 3

AOX protein is localized in mitochondria of cells from the testis and seminal vesicle (SV) sheaths. Immunoflorescence staining and confocal microscopy for the indicated proteins and DAPI, from a 10-day old male of genotype X/Y; UAS-AOX ^F6/2; tubGS/3, in the presence of mifepristone. AOX protein is localized to the outermost cell layer of these organs, where it overlaps that for the mitochondrial marker ATP5A, but not to germline cells at any stage of differentiation. The light microscopy image (left) is from a control male (w ¹¹¹⁸), used for illustration purpose only. Spermatogenesis takes place inside cysts, starting at the tip of the testes (upper panels - note the concentration of nuclei that represent the first stages of this process) and moving towards the proximal end of the organ as cell differentiation proceeds (middle panels - note the presence of a cyst containing onion-stage spermatids with their single mitochondrial mass, called the Nebenkern). At the proximal end of the testis, mature spermatozoid cells are released from the cyst and stored in the SV (lower panels - note the needle-shaped nuclei that is typical of these cells). Note also the low-level AOX expression in the somatic cells of the cysts, but not in the germline. See Additional file 1: Fig. S10 for comparable images from 3Xtub-AOX males