Nieber F et al. (2009), Comparative expression analysis of the neurogen...

XB-ART-39152

Dev Dyn 2009 Feb 01;2382:451-8. doi: 10.1002/dvdy.21845.

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Comparative expression analysis of the neurogenins in Xenopus tropicalis and Xenopus laevis.

Nieber F , Pieler T , Henningfeld KA .

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The Neurogenin (Ngn 1-3) family of proneural basic helix-loop-helix (bHLH) transcription factors are key regulators of vertebrate neurogenesis. In the developing vertebrate nervous system, the Ngns are essential for the commitment to a neuronal fate and participate in the specification of neuronal cell-type identity. Xenopus laevis is widely used as a model system to study the early events of vertebrate neurogenesis, however, only Ngnr-1, which is most closely related to the mammalian Ngn2, has been described and characterized. Presently, we describe a comparative expression analysis of the Ngn1-3 in X. tropicalis and X. laevis embryos. The Xenopus Ngns are present in overlapping, as well as unique regions of the nervous system starting at gastrula stages, suggesting distinct roles for this important family of transcriptional factors in the establishment of the amphibian nervous system.

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Species referenced: Xenopus tropicalis Xenopus laevis
Genes referenced: en2 neurog1 neurog2 neurog3 nkx2-1 otp ptf1a tubb2b

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	Figure 2. Comparative in situ hybridization analysis of X. tropicalis Ngn1, Ngn2, Ngn3, and X. laevis Ngn1, Ngnr-1, and Ngn3 during early development. The antisense probes are indicated to the left. Shown is stage 11, dorsal view; stage 12, dorsal view, anterior up; stage 15 left panel, dorsal view, anterior up; stage 15, right panel anterior view; stage 20/22 left panel, lateral view; stage 20/22 right panel, anterior view. bp, blastopore; e, eye; hb, hindbrain; i, intermedial; l, lateral; m, medial; op, olfactory placode; otp, otic placode; tg, trigeminal-profundal placode.
	Figure 3. A: Double in situ hybridization analysis of X. laevis Ngn1, Ngnr-1, Ngn3 (dark blue) with the mid-hindbrain boundary marker En-2 (red), marked by black arrowheads. Stages are indicated in the lower left corner, embryos are shown in an anterior view. B: Double in situ hybridization analysis of X. laevis Ngn1, Ngnr-1, Ngn3 (dark blue) with the marker for postmitotic neurons N-tubulin (red). The medial (m), intermediate (i) and lateral stripes (l) of N-tubulin expression are indicated in the transversal sections.
	Figure 4. A: Comparative in situ hybridization analysis of X. tropicalis Ngn1, Ngn2, Ngn3, and X. laevis Ngn1, Ngnr-1, and Ngn3 in stage 30 embryos. Probes are indicated on the left of each line of embryos. Shown: first panel, lateral view, anterior to the left; second panel, close-up of the head region; third panel dorsal view of head region; fourth panel, transverse section at the level of the retina; fifth panel, transverse section at the level of the otic vesicle. The transversal sections were performed with embryos stained for both Ngn (dark blue) and N-tubulin (red). VII, facial epibranchial placode; IX, glossopharyngeal epibranchial placode; X1, first vagal epibranchial placode; X2, second vagal epibranchial placode; X3, third vagal epibranchial placode; hb, hindbrain; mb, midbrain; nc, notochord; op, olfactory placode; vOT, otic vesicle; tg, trigeminal placode; pg, pineal gland; pP, posterior lateral line placode; pM, middle lateral line placode; pAD, anterodorsal lateral line placode; r, retina. B: Double in situ hybridization of stage 30 X. laevis embryos with Ngn1, Ngnr-1, Ngn3 (dark blue) and the mid-hindbrain boundary marker En-2 (red) or with the ventral forebrain marker Nkx2.1 (red) (transversal section). Black arrowhead marks the expression of Ngn3 in the ventral forebrain.
	Figure 5. A: Comparative in situ hybridization analysis of X. tropicalis Ngn1, Ngn2, Ngn3, and X. laevis Ngn1, Ngnr-1, and Ngn3 in stage 41/43 embryos. Probes are indicated on the left. Left panel shows a lateral view of the embryos, right panel shows a dorsal close up of the head region. Red arrowheads indicate the ventral Ngn3 expression in intestine B: Transverse section showing X. tropicalis Ngn2 expression in the ciliary marginal zone (CMZ) of the retina. C: Double in situ hybridization of analysis of X. laevis Ngn3 (dark blue) and Ptf1a/p48 (red) in stage 41 gut explants. Red arrowheads mark stained enteroendocrine cells. duo, duodenum; int, intestine; lt, lung tube; lv, liver; oes, esophagus; pa, pancreas, pr, proctodeum; st, stomach.