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We report an isolation of a cDNA containing armadillo motif (XAMP: Xenopus armadillo motif protein) and its expression during Xenopus development. The open reading frame of Xamp encodes a predicted protein of 275 amino acids including an armadillo motif, and a bipartite nuclear localization signal. Xamp shares significant homology with a putative mouse protein (GeneBank AK009402) in the database. It is expressed both maternally and zygotically. Xamp is localized to the animal region of an egg and in the ectoderm of a gastrula stageembryo. At the neurula stages, Xamp is expressed in the dorsal region of neural tube from which presumptive sensory neurons arise. In addition to its neural tissue specific expression, Xamp transcripts are found to be localized in the developing gut tube. At the early tadpole stage, Xamp is expressed predominantly in the pharyngeal endoderm. As further development proceeds, its expression domain expands to include the entire foregut region but excludes the midgut and hindgut regions. This polarized pattern of expression persists until stage 46 after which, anterior specific expression of Xamp sharply decreases. These results suggest that Xamp may have a role in the neural tissue specification and gutendoderm patterning during the Xenopus development.
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14516665
???displayArticle.link???Mech Dev
Fig. 2. The temporal expression pattern of Xamp during Xenopus embryogenesis.
RT-PCR analysis shows that Xamp transcript is expressed maternally.
After gastrula stage, Xamp mRNA is reduced in a whole embryo.
2RT lane is a control of RT-PCR on stage 8 whole embryo RNA in the
absence of reverse transcriptase. ODC serves as a loading control.
Fig. 3. Localization of Xamp transcripts in whole embryos and isolated guts. (A) The lateral view of a fertilized egg showing that maternal transcripts of Xamp
are localized in the animal region of egg. (B) The dorsolateral view of an early gastrulaembryo (stage 10). Xamp mRNA is restricted to the dorsal ectoderm.
Arrowhead indicates the dorsal lip of blastopore. (C) The dorsal view of a neurulaembryo (stage 18). Xamp is expressed in the prospective sensory neuron area
of the neural tube (arrow). (D) A sagittal section of stage 18/19 embryo showing Xamp expression in the most dorsal region of neural tube (nt). (E) Isolated
whole guts. (E) Stage 36 embryonic gut shows Xamp localization in the developing pharynx (ph). Anterior is to the left. (F) Left side view of Xamp expression
in the stage 38/39 gut. Xamp is expressed in pharynx (ph) and liver bud (li) of foregut. (G) Ventrolateral view of stage 41 gut. Xamp is expressed in the pharynx
(ph) and foregut including liver (li), pancreas (p), and stomach (st). The posterior expression boundary of Xamp expands to the transitional zone/intestine
boundary (arrowhead). (H) Fully differentiated stage 49 gut. No positive signaling is detected at this stage. (I) A frontal section of the stage 42 tadpole shows
that Xamp expression is detected in the endoderm of pharynx and foregut-derived organs. Abbreviations: int, intestine; li, liver; nt, neural tube; p, pancreas; pe,
pharyngeal endoderm; st, stomach; si, small intestine.
Fig. 4. Spatiotemporal regulation of Xamp expression in developing gut
endoderm. (A) Schematic diagram of gut isolation and dissection. (B) RTPCR
analysis of Xamp from the isolated gut tube explants. Xamp is strongly
expressed in the pharyngeal explants of stage 36 gut. At the stage 41/42,
Xamp is expressed in both pharynx and foregut explants. At stage 49, Xamp
expression disappears throughout the whole gut. -RT lane is a control of
RT-PCR on pharynx RNA of stage 36 in the absence of reverse transcriptase.
EF1-a served as a positive control for quantifying RNA levels in the
different samples. Abbreviations: F, foregut; G, gut tube; M/H, midindgut;
P, pharynx.
armc1(armadillo repeat containing 1) gene expression in Xenopus laevis embryos, NF stage 10, as assayed by in situ hybridization. Dorsal view, Animal up.
armc1(armadillo repeat containing 1) gene expression in Xenopus laevis embryos, NF stage 18, as assayed by in situ hybridization. Dorsal view: anterior up.
armc1(armadillo repeat containing 1) gene expression in the dissected gut of Xenopus laevis embryos, NF stage 38, as assayed by in situ hybridization. Lateral view: anteriorleft, dorsal up.
