title: Expression of Sox and fibrillar collagen genes in lamprey larval chondrogenesis with implications for the evolution of vertebrate cartilage.
abstract: Lampreys possess unique types of cartilage in which elastin-like proteins are the dominant matrix component, whereas gnathostome cartilage is mainly composed of fibrillar collagen. Despite the differences in protein composition, the Sox-col2a1 genetic cascade was suggested to be conserved between lamprey pharyngeal cartilage and gnathostome cartilage. We examined whether the cascade is conserved in another type of lamprey cartilage, the trabecular cartilage. We found that SoxD and SoxE are expressed in both trabecular and pharyngeal cartilages. However, trabecular cartilage shows no clade A fibrillar collagen gene expression, including genes expressed in pharyngeal cartilage of this animal. On the basis of these observations, we propose that lampreys possess an ancestral type of cartilage that is similar to amphioxus gill cartilage, and in this respect, gnathostome cartilage can be regarded as derived for the loss of elastin-like protein as a cartilage component and recruitment of fibrillar collagen, which is included as a minor component in the ancestral cartilage, as the main component.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Ohtani
authors.forename: Tuoya
authors.initials: T
authors.lastname: Yao
authors.forename: Mari
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Rie
authors.initials: R
authors.lastname: Kusakabe
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kuratani
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wada
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001934:Branchial Region / Q000166:cytology; D002356:Cartilage / Q000166:cytology; D002454:Cell Differentiation; D019902:Chondrocytes / Q000166:cytology; D020219:Chondrogenesis / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D024022:Fibrillar Collagens / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D007798:Lampreys / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D055747:SOX Transcription Factors / Q000235:genetics / Q000378:metabolism; D014714:Vertebrates / Q000502:physiology*
chemical_list: D024022:Fibrillar Collagens; D055747:SOX Transcription Factors