%0 Journal Article
%T Evolution of the osteoblast: skeletogenesis in gar and zebrafish
%A B Frank Eames
%A Angel Amores
%A Yi-Lin Yan
%A John H Postlethwait
%J BMC Evolutionary Biology
%D 2012
%I BioMed Central
%R 10.1186/1471-2148-12-27
%X Results provided no evidence for the evolution of novel functions among gene duplicates in zebrafish compared to the gar outgroup, but our findings shed light on the evolution of the osteoblast. Zebrafish and gar chondrocytes both expressed col10a1 as they matured, but both species' osteoblasts also expressed col10a1, which tetrapod osteoblasts do not express. This novel finding, along with sox9 and col2a1 expression in developing osteoblasts of both zebrafish and gar, demonstrates that osteoblasts of both a teleost and a basally diverging ray-fin fish express components of the supposed chondrocyte molecular fingerprint.Our surprising finding that the "chondrogenic" transcription factor sox9 is expressed in developing osteoblasts of both zebrafish and gar can help explain the expression of chondrocyte genes in osteoblasts of ray-finned fish. More broadly, our data suggest that the molecular fingerprint of the osteoblast, which largely is constrained among land animals, was not fixed during early vertebrate evolution.Skeletal tissues provide invaluable traits to document vertebrate evolution and to reveal the mechanistic basis for evolutionary change. Two main processes underlie skeletal development: histogenesis--histological differentiation of skeletal tissues--and morphogenesis--acquisition of skeletal element location, shape, and size. Skeletal histogenesis involves overt differentiation of cells that secrete the extracellular matrix of cartilage and bone (chondrocytes and osteoblasts, respectively), and follows the mesenchymal condensation of skeletogenic cells. Skeletal morphogenesis directs such differentiation events in space and time. While many studies propose a molecular genetic basis for evolutionary changes to skeletal morphogenesis [1-5], the evolution of skeletal histogenesis among vertebrates is fertile ground for additional molecular analyses [6,7].Each cell type achieves and performs its function by employing a specific set of genes, recently termed
%U http://www.biomedcentral.com/1471-2148/12/27