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Gene Expr Patterns
2006 Jan 01;62:180-6. doi: 10.1016/j.modgep.2005.06.007.
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Multiple noggins in vertebrate genome: cloning and expression of noggin2 and noggin4 in Xenopus laevis.
Eroshkin FM
,
Ermakova GV
,
Bayramov AV
,
Zaraisky AG
.
???displayArticle.abstract??? Noggin is a neural inducer secreted by cells of the Spemann organizer. A single noggin gene was identified until very recently in all tested vertebrates. The only exception was zebrafish, in which two close homologs of noggin, named noggin1 and noggin3, and one gene more diverged from them, noggin2, were cloned. Nevertheless, finding of three zebrafish noggins was attributed exclusively to specific genomic duplications in the fish evolutionary branch. However, very recently it was shown that Xenopus tropicalis have additional noggin homolog, called noggin2 [Fletcher, R.B., Watson, A.L., Harland, R.M. (2004). Expression of Xenopus tropicalis noggin1 and noggin2 in early development: two noggin genes in a tetrapod. Gene Expr. Patterns 5, 225-230], which indicates at least two independent noggin genes in vertebrate phylum. Now we report identification of two novel noggin homologs in each of so evolutionary distant species as Xenopus laevis, chicken and fugu. One of these noggins is ortholog of the X. tropicalis and zebrafish noggin2, whereas another, named noggin4, was not known previously. In the X. laevis embryos, the expression of noggin2 very resembles that of its counterpart in X. tropicalis: it begins with neurulation at the anterior margin of the neural plate and, afterward, continues mainly in the forebrain and dorsal hindbrain. At the same time, noggin4 is expressed starting from the beginning of gastrulation, throughout the ectoderm, with a local expression maximum in the prospective anteriorneurectoderm. Later, it is widely expressed on the dorsal side of embryo, including neural tube, eyes, otic vesicles, cranial placodes, branchial arches, and somites. The data presented here demonstrate that the vertebrate phylum contains at least three distinct noggin genes.
Fig. 2. Expression of the X. laevis noggins at the stages 10,5–18. (A) Results of RT-PCR of the total RNA from embryos at the indicated stages with primers to noggin1 (N1), noggin2 (N2), noggin4 (N4) and EF-1-alpha (EF) as the loading control. (B-O) Results of the whole-mount in situ hybridization. The embryos are shown from the dorsal side (B, J and M), from the anterior, dorsal side upward (C, D and O), from the vegetal pole, dorsal side upward (F and G), from the right side, dorsal side upward (K, N), split sagittally, anterior to the right (E, L). (O1) Histological frontal section of the embryo shown on (O) at the level indicated by red dotted line. Abbreviations: Aem—anterior endomesoderm; Am—anterior margin of the neural plate; Anp—anterior neural plate; Ar—archenteron roof; Bl—blastopore; Dbl—dorsal blastopore lip; Ep—epidermis; Gc—gastrocoel; Nc—presumptive neural crest; Nf—neural fold; Nop—neural plate; Np/not—notoplate/notochord; Pnp—posterior neural plate; Sm—presumptive somites.
Fig. 3. Expression of the X. laevis noggins at the stages 24 and 26. (A–F) Results of the whole-mount in situ hybridization. All embryos are shown from the right side, anterior to the right, dorsal upward. Embryos shown on C and F were cleared in the mixture of benzyl benzoate and benzyl alcohol. (D1–F4) Histological sections of embryos hybridized in whole-mount. (D1 and D2) Sections of embryos at stage 24 at the levels indicated on (D). (F1–F4) Sections of embryos at stage 26 at the levels indicated on (F). On D1, F1 and F2, dorsal to the top; on D2, F3 and F4, anterior to the right. Abbreviations: Ba—branchial arches; Cg—cement gland; Fb—fore brain; H—heart; Hb—hind brain; Mes—mesencephalon; Nc—neural crest cells; Nt—neural tube; Not—notochord; Ov—otic vesicle; Pe—presumptive pigmented epithelium; Ret—retina; Sm—somites.
nog2 (noggin 2) gene expression in Xenopus laevis embryos, NF stage 15, as assayed by in situ hybridization, anterior view, dorsal up.
nog2 (noggin2) gene expression in Xenopus laevis embryos, NF stage 26, as assayed by in situ hybridization, lateral view, anteriorright, dorsal up.
nog4 (noggin4) gene expression in Xenopus laevis embryos, NF stage 12.5, as assayed by in situ hybridization, lateral view, anteriorright, dorsal up.
nog4 (noggin4) gene expression in Xenopus laevis embryos, NF stage 18, as assayed by in situ hybridization, anterior view, dorsal up.
nog4 (noggin4) gene expression in Xenopus laevis embryos, NF stage 26, as assayed by in situ hybridization, lateral view, anteriorright, dorsal up.
