Sulphated glycosaminoglycans and proteoglycans in the developing vertebral column of juvenile Atlantic salmon (Salmo salar).
Bottom Line: In addition, the distribution of the different GAG types in normal and malformed vertebral columns from 15 g salmon was compared.A changed expression pattern of GAGs was found in the malformed vertebrae, indicating the involvement of these molecules during the pathogenesis.Our study reveals the importance of GAGs in development of vertebral column also in Atlantic salmon and indicates that a more comprehensive approach is necessary to completely understand the processes involved.
Affiliation: Nofima AS, 1430, Ås, Norway.
In the present study, the distribution of sulphated glycosaminoglycans (GAGs) in the developing vertebral column of Atlantic salmon (Salmo salar) at 700, 900, 1100 and 1400 d° was examined by light microscopy. The mineralization pattern was outlined by Alizarin red S and soft structures by Alcian blue. The temporal and spatial distribution patterns of different types of GAGs: chondroitin-4-sulphate/dermatan sulphate, chondroitin-6-sulphate, chondroitin-0-sulphate and keratan sulphate were addressed by immunohistochemistry using monoclonal antibodies against the different GAGs. The specific pattern obtained with the different antibodies suggests a unique role of the different GAG types in pattern formation and mineralization. In addition, the distribution of the different GAG types in normal and malformed vertebral columns from 15 g salmon was compared. A changed expression pattern of GAGs was found in the malformed vertebrae, indicating the involvement of these molecules during the pathogenesis. The molecular size of proteoglycans (PGs) in the vertebrae carrying GAGs was analysed with western blotting, and mRNA transcription of the PGs aggrecan, decorin, biglycan, fibromodulin and lumican by real-time qPCR. Our study reveals the importance of GAGs in development of vertebral column also in Atlantic salmon and indicates that a more comprehensive approach is necessary to completely understand the processes involved.
No MeSH data available.
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Mentions: Alcian blue staining of the consecutive sections showed the distribution of sulphated GAGs in the notochord and surrounding tissue (Fig. 3). Sections collected from fish at 700 d° showed a strong and uniform blue staining of the notochordal sheath, arcualia and a weaker staining of the surrounding tissue (Fig. 3a–c). In the ventral part of the sheath where mineralization of the chordacentra was observed, regularly arranged areas of weaker staining appeared, demarcated on both sides by darker blue colour (arrow, Fig. 3a, b). In the transverse sections of notochord (Fig. 3c), a blue somewhat faint-stained network was evident in the lumen, showing the presence of GAGs also in chordoblasts and chordocytes. Furthermore, the templates for both neural and haemal arches were clearly outlined at 700 d° (arrows, Fig. 3c). In sections collected from fish at 900 d°, a change in the staining pattern appeared: a darker blue staining was seen in the areas for development of the future IVRs (Fig. 3e). The staining intensity of the chordocyte network of the notochord lumen increased. Although the cartilaginous appearance of the arcualia (ac) became visible at 700 d° (Fig. 3c), the cartilaginous nature of the growing arcualia was more evident at 900 d° (Fig. 3d–f). No major differences were observed in the distribution pattern of GAGs in sections collected at 1100 d° (Fig. 3g–i). At 1400 d°, the IVRs of the sheath with the chordoblasts and chordocytes exhibited a darker blue colour (Fig. 3j–l). In the IVRs, endplates were surrounded by a darker blue layer (Fig. 3k). In the transverse section at 1400 d°, concentric lamellar structures appeared in the sheath (Fig. 3l). The results after staining longitudinal sections from 15 g salmon with Alcian blue showed strong staining in the various compartments of the vertebral column such as the cartilaginous tissue of the amphicoel, the IVRs with the notochordal sheath and the bony endplates and the chordoblast layer as well as the chordocytes in the lumen (Fig. 3m), revealing an abundance of sulphated GAGs in mineralized as well as unmineralized tissue of the salmon vertebral column in adulthood.Fig. 3
No MeSH data available.