|
Description: FISH analysis of piRNA localization revealed a strong signal in the nucleolus of Sertoli cells, in agreement with our observed miRNA pattern. The images of the two piRNAs shown in Figure 6S are essentially identical to all piRNAs tested. This nucleolar localization was abolished in MIWI-null testis (Figure 6C; Sertoli cell, insert, yellow arrow). The effect of MIWI deletion is surprising since expression of MIWI protein was reported in the cytoplasm of spermatocytes and spermatids but not Sertoli cells (Deng & Lin 2002, Kotaja et al. 2006). It is possible that the greater levels of expression in spermatocytes and spermatids have obscured visual- ization of MIWI staining in the Sertoli cells where MIWI could be responsible for localization of piRNAs to the nucleolus and possibly their processing. In meiotic spreads, only piR-7 and piR-17005 showed strong localization to the dense body, chromosome cores and possibly telomeres, while the other three (piR-17037, 17043, 17080) showed very weak or no association (Figure 6D). MIWI deletion did not affect piRNAs localization in the meiotic nucleus.
|