February 1, 2005;
Xenopus tropicalis peroxidasin gene is expressed within the developing neural tube and pronephric kidney.
Peroxidasin, originally identified in Drosophila, is a member of the myeloperoxidase
family with a novel domain structure. It is proposed that peroxidasin is secreted and has functions associated with stabilization of the extracellular matrix. We report the identification of the Xenopus tropicalis orthologue of the peroxidasin gene. We show that the predicted protein sequence of Xenopus peroxidasin shows high sequence identity with the human orthologue and that the exon structure is highly conserved between the two species. We describe the first detailed developmental expression pattern for peroxidasin in a vertebrate species. Maternal expression of Xtpxn is localized to the animal hemisphere where it persists through early cleavage
stages. Initial zygotic Xtpxn expression is detected in the developing neural tube and becomes localized to the hindbrain
. Xtpxn is expressed in the primordium
of the pronephric kidney
and expression persists in the pronephric tubules and duct
throughout development. Potential roles for peroxidasin during early vertebrate development are discussed.
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Figure 5. Whole-mount in situ hybridization analysis of Xenopus tropicalis peroxidasin expression during development. Whole-mount in situ hybridizations showing the expression of Xtpxn at various stages. A: Side view of a zygote at 60 min postfertilization. The animal hemisphere is to the top. B: Cut face view of a zygote bisected along the animal vegetal axis. The animal hemisphere is to the top. C: Side view of two-cell stage embryo. The animal hemisphere is to the top. D: An animal view of a 32-cell stage embryo. E: Cut face view of a blastula stage 9 bisected along the animal vegetal axis. The animal hemisphere is to the top. F: Dorsal view of a neurula stage 17 embryo. Anterior is to the left. G: Lateral view of a neurula stage 17 embryo. Anterior is to the left. H: Lateral view of stage 23 embryo. Anterior is to the left. I: Lateral view of a early tailbud stage 27 embryo. J: High-power dorsal view of the hindbrain region of an early tailbud stage 27 embryo. K: Lateral view of a tailbud stage 31 embryo. Anterior is to the left. L: High-power view of the developing pronephros on the flank of a tailbud stage 31 embryo. M: The anterior region of a tailbud stage 34 embryo. N: A dorsal view of the midbrain/hindbrain region of a tailbud stage 34 embryo. O: The posterior region of a tailbud stage 34 embryo. P: High-power view of the developing pronephros on the flank of a tailbud stage 34 embryo. Q: A 10- mu m transverse section through a stage 34 embryo at the level of the pronephros. R: High-power view of 10- mu m transverse section through pronephric duct of a stage 34 embryo. bcl, blastocoele cavity; bra, branchial arches; end, endoderm; eye, eye; hb, hindbrain; mhj, midbrain/hindbrain junction; nne, non-neural ectoderm; nt, neural tube; pcd, proctodeum; pf, posterior fin; pnd, pronephric duct; pnt, pronephric tubule; tlb, tail bud.