XB-ART-9829Mech Dev January 1, 2001; 100 (1): 137-40.
The vegetally localized mRNA fatvg is associated with the germ plasm in the early embryo and is later expressed in the fat body.
Vegetally localized RNAs in Xenopus oocytes have been implicated in the establishment of the primary germ layers and the formation and development of the primordial germ cells. fatvg mRNA is localized through the late pathway to the vegetal cortex. Like Vg1 mRNA fatvg is distributed throughout the entire cortex; however, unlike Vg1 there is a small fraction of the fatvg mRNA that is associated with the mitochondrial cloud. In early cleavage stage embryos, fatvg mRNA is associated with the germ plasm located at the tips of the vegetal blastomeres of the embryo. While several localized RNAs that follow the Message Transport Organizer (METRO) pathway have been found in the germ plasm in embryos, fatvg is a late pathway RNA that is associated with the germ plasm. In tadpoles, fatvg mRNA shows a novel pattern of expression which is distinct from the germ cell lineage and is detected at the dorso-anterior margin of the endodermal mass along the midline in two clusters of cells. fatvg mRNA expression is also detected later in the developing fat bodies, the major adipose tissues of the frog.
PubMed ID: 11118900
Article link: Mech Dev
Species referenced: Xenopus laevis
Genes referenced: gdf1 pgat plin2
Article Images: [+] show captions
|Fig. 1. fatvg mRNA is associated with the germ plasm. Digoxigenin-labeled antisense fatvg probe was hybridized to early Xenopus embryos. (A–C) fatvg mRNA was detected in the germ plasm at the peripheries of the blastomeres in the endoderm of two-cell stage (A), 16/32-cell stage (B) and blastula stage embryos (C). (E) No staining was detected in the germ plasm when the sense probe was used. Higher magnifications of (C) and (E) showing the germ plasm regions in the boxed areas are shown in (D) and (F), respectively. (G) fatvg mRNA was detected in the germ plasm at a perinuclear position in gastrula stage embryos. (H) A higher magnification of (G) with Hoechst staining is shown to indicate positions of the nuclei. Arrows point to fatvg signal.|
|Fig. 2. Expression of fatvg mRNA in ovaries isolated from young frogs. (A) fatvg expression was detected in the developing oocytes as shown by in situ hybridization. (B) No staining was detected in the ovary when the sense probe was used. Arrows indicate fatvg mRNA expression. lu, lumen of developing ovaries|
|Fig. 3. Expression of fatvg mRNA in stage 40 tadpoles. (A) fatvg expression was detected at the dorso-anterior margin of the endodermal mass by in situ hybridization, as shown on a transverse section of a tadpole stage embryo. (B) A higher magnification of the boxed area in (A) is shown. (C) fatvg mRNA was detected as two symmetric stripes located on the endodermal mass, as shown on a cross-section of a tadpole along the dorsal-ventral axis at the position indicated in (A). (D) A sense control section of a tadpole at a corresponding position along the dorsal-ventral axis. No staining was detected. (E) Xpat was used as a marker for primordial germ cells. The expression pattern of Xpat is distinct from cells expressing fatvg shown in (C). Arrows indicate cells expressing fatvg mRNA. Arrowhead points to Xpat expressing cells. e, eye; en, endoderm; no, notochord; s, somite.|
|Fig. 4. Expression of fatvg mRNA in stage 47 tadpoles. (A) fatvg mRNA was detected by in situ hybridization in two clusters of cells above the coelomic lining, as indicated by dotted lines. (B) A higher magnification of a section similar to (A) is shown. (C) Hoechst staining of (B) to show the position of nuclei in the cell clusters which are outlined in white. Arrows indicate cells expressing fatvg. dm, dorsal mesentery; i, intestine; no, notochord; s, somite; w, Wolffian duct.|
|Fig. 5. Expression of fatvg mRNA in the fat bodies. (A) fatvg was detected in the fat bodies in stage 56 tadpoles by in situ hybridization. The vacuole-like structures were fat droplets. Hybridization signals were detected in the cytoplasm, which had been displaced to the peripheries of the cells by the fat droplets. (B) Hoechst staining of the section in (A) to show the positions of the nuclei on the peripheries of the cells in the fat bodies. (C) No staining was detected when the sense probe was used. (D) Hoechst staining of the section as shown in (C).|