Collagen type XI α1 may be involved in the structural plasticity of the vertebral column in Atlantic salmon (Salmo salar L.)

Abstract

SUMMARY Atlantic salmon (Salmo salar L.) vertebral bone displays plasticity in structure, osteoid secretion and mineralization in response to photoperiod. Other properties of the vertebral bone, such as mineral content and mechanical strength, are also associated with common malformations in farmed Atlantic salmon. The biological mechanisms that underlie these changes in bone physiology are unknown, and in order to elucidate which factors might be involved in this process, microarray assays were performed on vertebral bone of Atlantic salmon reared under natural or continuous light. Eight genes were upregulated in response to continuous light treatment, whereas only one of them was upregulated in a duplicate experiment. The transcriptionally regulated gene was predicted to code for collagen type XI α1, a protein known to be involved in controlling the diameter of fibrillar collagens in mammals. Furthermore, the gene was highly expressed in the vertebrae, where spatial expression was found in trabecular and compact bone osteoblasts and in the chordoblasts of the notochordal sheath. When we measured the expression level of the gene in the tissue compartments of the vertebrae, the collagen turned out to be 150 and 25 times more highly expressed in the notochord and compact bone respectively, relative to the expression in the trabecular bone. Gene expression was induced in response to continuous light, and reduced in compressed vertebrae. The downregulation in compressed vertebrae was due to reduced expression in the compact bone, while expression in the trabecular bone and the notochord was unaffected. These data support the hypothesis that this gene codes for a presumptive collagen type XI α1, which may be involved in the regulatory pathway leading to structural adaptation of the vertebral architecture.

Vertebral deformities in farmed Atlantic salmon (Salmo salar L.) - etiology and pathology

“…There appears to be a delay of several weeks between the induction and the development of a deformity (Wargelius et al., 2010a; Grini et al., 2011). The expression level of several genes is different in deformed compared to normal vertebrae; collagen type XI a1 gene is down‐regulated in the compact but not in the trabecular bone (Wargelius et al., 2010b) and MMP‐13 is up‐regulated in both compact and trabecular bone of compressed vertebrae (Wargelius et al., 2010b). Osteonectin (SPARC) gene, MMP‐9 and MMP‐13 are up‐regulated and collagen I, collagen X and osteocalcin genes are down‐regulated in completely fused vertebrae (Ytteborg et al., 2010b).…”

Continuous light induces bone resorption and affects vertebral morphology in Atlantic salmon (Salmo salarL.) fed a phosphorous deficient diet

“…Collagen XI α1 has been cloned in Atlantic salmon, where it is expressed in the osteoblasts and chordoblasts of the vertebral column (Wargelius et al . ). How the vitamin D system and bone of fish under continuous light responds to different dietary P levels when compared to fish under a short day has never been studied.…”

Four stages characterizing vertebral fusions in Atlantic salmon

“…However, cellular and molecular events during pathological bone development in salmon have been little described and only a few studies have been published (e.g. Wargelius et al., 2010a,b; Ytteborg et al., 2010a,b,c). Our group recently finished a comprehensive study on temperature induced vertebral fusions in Atlantic salmon, where we described various stages of pathological development using molecular tools.…”