Phylogenetic analysis of infectious salmon anaemia virus isolates from Norway, Canada and Scotland

The sequences of gene segments 2 and 8 from 10 different isolates of infectious salmon anaemia Virus (ISAV) sampled in Norway, Canada and Scotland between 1987 and 1999 were determined and compared. Pairwise comparisons revealed a high degree of homology between the European isolates, with identities of 98 to 100% for both genes examined. The Canadian isolate showed identities of 84 and 87 to 88 % with the European isolates for the nucleotide sequence of segments 2 and 8, respectively. Phylogenetic analyses were performed to establish the interrelationship between the European virus isolates. The evolutionary rate based on 4 Norwegian isolates clustered together in the analysis of segment 2 was calculated to be 0.96 x 10(-3) nucleotides site(-1) yr(-1). On the basis of this mutation rate it was estimated that the Norwegian Glesvaer 90 and Canadian Bay of Fundy 97 isolates diverged around 1900, which coincides with transportation of salmonids between Europe and North America starting in the late nineteenth century

Collagen type XI 1 may be involved in the structural plasticity of the vertebral coulm in Atlantic salmon (Salmo salar L.)

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 a1, 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 becular 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 a1, which may be involved in the regulatory pathway leading to structural adaptation of the vertebral architecture