July 1, 2000;
DEADSouth is a germ plasm specific DEAD-box RNA helicase in Xenopus related to eIF4A.
was selected in a screen for localized RNAs in Xenopus oocytes. In situ hybridization analysis shows that DEADSouth
localizes to the vegetal cortex via the mitochondrial cloud early in oogenesis and segregates with germ plasm during early embryogenesis. These results lend further support for the general concept that the role of the early RNA localization pathway in Xenopus is to localize germ cell components (reviewed in King, M.L., Zhou, Y., Bubunenko, M. , 1999. BioEssays 21, 546-557). Further analysis shows that DEADSouth
is a germline specific RNA, found exclusively within the germ plasm of oocytes and PGCs, as well as in male germ cells. Sequence comparisons with DEADSouth
show it to be a member of a small sub-family of the DEAD-box RNA-dependent helicases related to eIF4A
[+] show captions
Fig. 3. DEADSouth RNA is localized to the germ plasm during oogenesis. (A) Sectioned whole-mount in situ of a clump of Pre-I oocytes; arrows indicate oocyte with perinuclear DEADSouth RNA. (B) Whole-mount of stage I and II oocytes. (C) Section through a stage II oocyte. (D) Whole-mount of stage III oocytes. (E) Section of stage III oocyte. (F) Whole-mount of stage IV oocytes. (G) Section of late stage IV oocyte. (H) Higher magnification of (G) showing sub-cortical staining. (I) Whole-mount of stage V and VI oocytes. Scale bars, (C,E,H) 20 μm; (G) 100 μm.
Fig. 4. DEADSouth RNA follows the same distribution pattern as germ plasm during embryogenesis. (A) Whole-mount in situ of a four-cell embryo; vegetal pole view showing ‘islands’ of DEADSouthpositive germ plasm. (B) Vegetal pole view of whole-mount of stage 7–8 embryos. (C) Plastic section of a PGC from dissociated stage 7/8 embryo showing peripheral DEADSouthstaining in the germ plasm (D) Whole-mount of a stage 10 embryo. Note the DEADSouth staining cells at the vegetal pole (lower right). (E) Plastic section of dissociated stage 10 cells showing one DEADSouth positive PGC. Note that DEADSouth staining appears to be perinuclear. (F) Higher magnification (63×) of PGC seen in (E). Whole-mount in situs were embedded in plastic and sectioned at 1 μm. Scale bars, (C) 10 μm; (E) 50 μm; (F) 20 μm.