Characterization of<i>collagen type 10a1</i>and<i>osteocalcin</i>in early and mature osteoblasts during skeleton formation in medaka

Abstract

Small teleost fish, such as the medaka (Oryzias latipes), are attractive animal models to study the genetics underlying bone formation. In order to characterize specific marker genes for bone formation in medaka, we identified and analyzed the gene expression of collagen type10a1 and osteocalcin during embryonic and larval development. In mammals and chicken, Collagen type 10a1 is expressed in hypertrophic chondrocytes. Osteocalcin, on the other hand, is expressed in mature osteoblasts, which have started to produce mineralized bone matrix. In contrast to mammals and chicken, expression of collagen type 10a1 during medaka embryogenesis is not found in chondrocytes but instead is restricted to intramembranous and perichondral bone formation. Therefore, collagen type 10a1 expression marks early osteoblasts. Osteocalcin, on the other hand is expressed in mature osteoblasts in mineralizing intramembranous and perichondral bone.