RESUMO
Little is known about the genes and processes involved in the development of otoliths. In this study, we isolated the biomineralization-related genes otolin and chondromodulin-1 (chm1) from medaka, and examined their spatiotemporal expression pattern as well as that of two other genes also related to biomineralization, i.e., sparc/osteonectin and type II collagen (col2a), during otic development in medaka. Our results demonstrated that all the tested genes were expressed in the otic vesicle, and that chm1 was exclusively expressed in the semicircular canal of the otic vesicle.
Assuntos
Biomarcadores , Regulação da Expressão Gênica no Desenvolvimento , Oryzias/embriologia , Oryzias/genética , Membrana dos Otólitos/embriologia , Animais , Colágeno Tipo II/genética , Embrião não Mamífero , Proteínas da Matriz Extracelular/genética , Proteínas de Membrana/genética , Organogênese , Osteonectina/genética , Canais Semicirculares/embriologia , Canais Semicirculares/metabolismoRESUMO
Putative sites of bone resorption in the acellular bony skeleton of the medaka fish (Oryzias latipes) were investigated primarily by RNA in situ hybridization and histological analysis. Numerous cells that displayed intense enzymatic activity of tartrate-resistant acid phosphatase (TRAP), the main marker of osteoclasts, were distributed in the pharyngeal region of this fish. Moreover, these cells expressed cathepsin K, an osteoclast-specific gene, as well as the genes for TRAP and vacuolar-type proton ATPase (V-ATPase). Some of the TRAP-positive cells displayed all of the morphological characteristics equivalent to those of mammalian- and bird-type osteoclasts. These cells were associated primarily with the shedding teeth and their supporting bones (pedicles), where alkaline phosphatase (ALPase)-positive osteoblasts were also located, implying progressive bone remodeling associated with tooth replacement in these regions. In contrast, the inner aspects of the neural and hemal arches of the vertebral column, which were the only sites of bone resorption other than the tooth-bearing bones, showed sporadically aligned flat mononuclear TRAP-positive cells without a ruffled border, indicating a different mode of bone remodeling in these regions. These results suggest the feasibility of medaka as a model animal for the investigation of bone-related abnormalities and their genetic backgrounds.
