January 1, 2000;
Xotx1 maternal transcripts are vegetally localized in Xenopus laevis oocytes.
is a Xenopus homeobox gene related to the Drosophila gene orthodenticle (otd). We previously reported that Xotx1
transcripts are already present in unfertilized egg
. Here we report that maternal Xotx1
mRNA is vegetally localized during oogenesis. In stage II oocytes Xotx1
transcripts are localized within the mitochondrial cloud, in a perinuclear position; later on, they are translocated to the vegetal cortex within the mitochondrial cloud. We also observed that in stage III oocytes the expression domain of Wnt11
is contained within the one of Xotx1
while, at stage IV, the Xotx1
expression domain is contained within the one of Vg1
[+] show captions
Fig. 2. Whole-mount in situ hybridization to oocytes of different stages showing the localized Xotx1 expression. (A) Stage II oocyte; (B ,C) early and late stage III oocyte; (D–F) early, mid and late stage IV oocyte. The bar in F represents 200 μm.
Fig. 4. Comparison between Xwnt11 and Xotx1; and between Vg1 and Xotx1 expression domains. In (A), a stage III oocyte is showed, hybridized with Xwnt11 (blue) and Xotx1 (brown); in (A′) is a section through the (A) sample. In (B), a stage IV oocyte is showed, hybridized with Xotx1 (blue) and Vg1 (brown); in (B′) is a section through the (B) sample.
Fig. 1. RNase protection analysis of Xotx1 expression during oogenesis from stage I oocytes up to stage VI oocytes. The X. laevis gene for ribosomal protein S8 (rp S8) (Pierandrei-Amaldi et al., 1982; Mariottini et al., 1988) is analyzed as an internal standard.
Fig. 3. Sections through oocytes of different stages hybridized with Xotx1. (A) Section of whole-mount of stage II oocyte showing Xotx1 transcripts within the mitochondrial cloud, that is quite near the vegetal cortex. (B–D) Section of whole-mount stage III, early and late stage IV oocyte respectively showing the anchoring of the mRNA to the vegetal cortex. The bar in D represents 200 μm.
otx1 (orthodenticle homeobox 1) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, oocyte stage IV, vegetal view.