Function of Pax1 and Pax9 in the sclerotome of medaka fish.

We examined the expression and functions of Pax1 and Pax9 in a teleost fish, the medaka Oryzias latipes. While Pax1 and Pax9 show distinct expression in the sclerotome in amniotes, we could not detect the differential expression of Pax1 and Pax9 in the developing sclerotome of the medaka. Furthermore, unlike the mouse, in which Pax1 is essential for development of the vertebral body, and where the neural arch is formed independent of either Pax1 or Pax9, our morpholino knockdown experiments revealed that both Pax1 and Pax9 are indispensable for the development of the vertebral body and neural arch. Therefore, we conclude that after gene duplication, Pax1 and Pax9 subfunctionalize their roles in the sclerotome independently in teleosts and amniotes. In Stage-30 embryo, Pax9 was strongly expressed in the posterior mesoderm, as was also observed for mouse Pax9. Since this expression was not detected for Pax1 in the mouse or fish, this new expression in the posterior mesoderm likely evolved in Pax9 of ancestral vertebrates after gene duplication. Two-month-old fish injected with Pax9 morpholino oligonucleotide showed abnormal morphology in the tail hypural skeletal element, which may have been related to this expression.

Odontogenic potential of bone marrow mesenchymal stem cells.

PURPOSE: This study aimed to investigate the odontogenic potential of bone marrow mesenchymal stem cells (BM-MSCs) for seeding in tooth regeneration. MATERIALS AND METHODS: In this study, BM-MSCs were co-cultured with oral epithelial cells derived from rat embryos. Expression of the odontogenic genes Pax9, DMP1, and DSPP was detected by the reverse-transcription polymerase chain reaction (RT-PCR) technique. To further characterize the odontogenic potential of BM-MSCs, the gold standard in vivo transplantation system was used. RESULTS: The results revealed that Pax9, DMP1, and DSPP expression was detected by RT-PCR only after co-culture of BM-MSCs and oral epithelial cells derived from embryos age E11.5. Histological analyses of the BM-MSCs/epithelial cell mass demonstrated the presence of tooth-like structures. CONCLUSIONS: The series of experiments both in vitro and in vivo demonstrated that BM-MSCs can differentiate into functional odontoblast-like cells. This implies that BM-MSCs may become a novel source of cells for seeding in tooth regeneration research.