Characterization of pax1, pax9, and uncx sclerotomal genes during Xenopus laevis embryogenesis

Abstract

Background: The axial skeleton develops from the sclerotome, a mesenchymal cell population derived from somites. Sclerotomal cells migrate from somites to the perinotochordal and perineural space where they differentiate into chondrocytes to form cartilage and bone. In anurans, little is known about the way how the sclerotome changes as development proceeds and how these events are regulated at the molecular level. Pax1, Pax9, and Uncx4.1 genes play a central role in the morphogenesis of the axial skeleton in vertebrates, regulating cell proliferation and chondrogenic specification of the sclerotome. Results: In this work, we cloned and examined through whole-mount in situ hybridization and reverse transcriptasepolymerase chain reaction the expression patterns of pax1, pax9, and uncx transcription factors in the anuran Xenopus laevis. Conclusions: We found that these genes are similarly expressed in the sclerotome and in the pharyngeal pouch. A detailed analysis of the location of these transcripts showed that they are expressed in different subdomains of the sclerotomal compartment and differ from that observed in other vertebrates. Developmental Dynamics 242:572-579, 2013. V C 2013 Wiley Periodicals, Inc.Key words: Anuran; Xenopus; Sclerotome; Backbone; pax1; pax9; uncx Key findings:The pax1, pax9, and uncx genes of the anuran Xenopus laevis were cloned. The pax1, pax9, and uncx genes are expressed in the pharyngeal pouch and sclerotome in the tail bud stage of Xenopus embryos. The pax1, pax9, and uncx genes are expressed in different subdomains of the sclerotome of Xenopus embryos.

Morphological and molecular evolution of the ultimobranchial gland of nonmammalian vertebrates, with special reference to the chicken C cells

“…Pax9, a member of the paired‐box transcription factor family, is required for the formation of a variety of organs and the regulation of many developmental processes associated with proliferation, compartment formation, and cell‐lineage specification (Peters et al, ). The gene is well conserved throughout vertebrate evolution and is expressed in all animals investigated, including fish, Xenopus, chick, mouse, and human (Ogasawara et al, ; Sanchez and Sanchez, ). In chick embryos at stage 22, Pax9 is strongly expressed in all pharyngeal pouches and the arch mesenchyme (Müller et al, ).…”

“…In chick embryos at stage 22, Pax9 is strongly expressed in all pharyngeal pouches and the arch mesenchyme (Müller et al, ). Furthermore, Pax9 expression is observed in Xenopus pharyngeal pouches (Sanchez and Sanchez, ). Pax9 may function in the formation of the ultimobranchial body in all vertebrates.…”

Ontogeny of the anuran urostyle and the developmental context of evolutionary novelty

“…We conducted histology of sectioned tissues and focused on ossification patterns of the hypochord. The sclerotome in frogs is formed in both rostral and caudal somites (26), but only the rostral somites (somites 1 to 12 in Xenopus tropicalis) contribute to the axial column (12,13); somites 9 to 12 contribute to the coccyx (equals fused postsacral vertebrae I to III) (8,12). The bony coccyx forms from three ossification centers, which subsequently enlarge via endochondral ossification (a detailed description of coccyx formation is given in SI Appendix).…”

Gene expression of the two developmentally regulated dermatan sulfate epimerases in the Xenopus embryo

“…At (neurula) stage 18, low-level Dse expression shifted from the lateral to the medial (now ventral) sensorial layer of the neural groove at the level of the future mid- and hindbrain (inset in Fig 2H ). Dse transcripts appeared in the ventro-medial edge of the somites ( Fig 2H ) that will give rise to the sclerotome [ 28 ]. In situ hybridization with a sense RNA probe did not show any signal in embryos at stage 15 and 18 ( Fig 2I and 2J ), confirming the specificity of Dse detection.…”