In aquaculture the risk of transmission of fish pathogens via eggs is reduced by disinfection in ... more In aquaculture the risk of transmission of fish pathogens via eggs is reduced by disinfection in ozonated seawater, but this treatment may delay or reduce hatching. The objective of this study was to investigate the tolerance of Atlantic cod, turbot and Atlantic halibut eggs to ...
Atlantic salmon (Salmo salar L.) fry were reared on a fishmeal-based diet with three different le... more Atlantic salmon (Salmo salar L.) fry were reared on a fishmeal-based diet with three different levels of vitamin D3 (0.2, 5 and 57 mg vitamin D3 kg–1 feed, ww) from first-feeding for 14 weeks. No significant differences were recorded in weight, length, specific growth rate, mortality, or kidney calcium concentration between the different dietary groups. No skeletal malformations or histopathological changes were recorded in any of the dietary groups. These results suggest Atlantic salmon fry to be highly tolerant of megadoses of vitamin D3 over a limited period of time.
The teleost backbone consists of amphicoelous vertebrae and intervertebral ligaments, both of whi... more The teleost backbone consists of amphicoelous vertebrae and intervertebral ligaments, both of which include notochord-derived structures. On the basis of a sequential developmental study of the vertebral column of Atlantic salmon (Salmo salar L.) from the egg stage up to early fry stage (300–2500 day-degrees) we show that the vertebral body consists of four layers or compartments, two of which are formed through mineralization of preformed collagenous tissue (the notochordal sheath and the intervertebral ligament) and two of which are formed through ossification. The three inner layers have ordered lamellar collagen matrixes, which alternate perpendicularly from layer to layer, whereas the outer layer consists of cancellous bone with a woven matrix. The bone layers also differ in osteocyte content. In this study we describe the structural details of the layers, and their modes of formation. The results are compared with previous descriptions, and possible phylogenetic implications are discussed.
The fine structure of the somatic muscles and their attachment to the cuticle in the pyenogonids ... more The fine structure of the somatic muscles and their attachment to the cuticle in the pyenogonids Nymphon (Chaetonymphon) macronyx G. O. Sars and Boreonymphon cf. abyssorum (Norman) is described. The muscles possess characteristics which are typical of arthropod slow muscle fibers: relatively long sarcomeres, a mean A‐band length of about 6 μm and a ratio of thin to thick contractile filaments of 4:1. The sarcotubular system consists of distinct t‐tubules, an irregular SR part and randomly distributed dyads and triads, the muscles are attached to the cuticle by specialized epidermal cells containing microtubules extending from the cuticular to the muscular side. The myoepidermal and epidermal‐cuticular junctions are described.
We performed a sequential morphological and molecular biological study of the development of the ... more We performed a sequential morphological and molecular biological study of the development of the vertebral bodies in Atlantic salmon (Salmo salar L.). Mineralization starts in separate bony elements which fuse to form complete segmental rings within the notochord sheath. The nucleation and growth of hydroxyapatite crystals in both the lamellar type II collagen matrix of the notochord sheath and the lamellar type I collagen matrix derived from the sclerotome, were highly similar. In both matrices the hydroxyapatite crystals nucleate and accrete on the surface of the collagen fibrils rather than inside the fibrils, a process that may be controlled by a template imposed by the collagen fibrils. Apatite crystal growth starts with the formation of small plate-like structures, about 5 nm thick, that gradually grow and aggregate to form extensive multi-branched crystal arborizations, resembling dendritic growth. The hydroxyapatite crystals are always oriented parallel to the long axis of the collagen fibrils, and the lamellar collagen matrices provide oriented support for crystal growth. We demonstrate here for the first time by means of synchroton radiation based on X-ray diffraction that the chordacentra contain hydroxyapatite. We employed quantitative real-time PCR to study the expression of key signalling molecule transcripts expressed in the cellular core of the notochord. The results indicate that the notochord not only produces and maintains the notochord sheath but also expresses factors known to regulate skeletogenesis: sonic hedgehog (shh), indian hedgehog homolog b (ihhb), parathyroid hormone 1 receptor (pth1r) and transforming growth factor beta 1 (tgfb1). In conclusion, our study provides evidence for the process of vertebral body development in teleost fishes, which is initially orchestrated by the notochord.
: This study describes the long‐term effects of surgical ablation of the pineal gland on the spi... more : This study describes the long‐term effects of surgical ablation of the pineal gland on the spine of 3‐yr‐old Atlantic salmon (Salmo salar L.) with a mean weight of 3.2 kg. Radiographic examinations showed that 82% of the pinealectomized fish developed marked lateral (scoliosis) and dorso‐ventral spinal curvatures. The proportions of the individual vertebral bodies and their mechanical properties were also altered. The stiffness, yield limit and resilience of the vertebral bodies, as measured by compression in the cranio‐caudal direction, were significantly lower in the pinealectomized than in the sham‐pinealectomized group. Calcium, phosphorous and total mineral content of the vertebral bodies were also significantly lower in the pinealectomized fish, while these parameters were similar in scales in the two groups. Alterations of the spinal curve accompanied by changes in the proportions, mechanical strength and mineral content of the vertebral bodies of the pinealectomized salmon indicate that melatonin has several functions related to vertebral bone growth. As the lesions found in salmon are similar to the spinal malformations observed in avian species and mammals after pinealectomy, this study strengthens the hypothesis of a phylogenetically conserved function of the pineal gland related to skeletal development.
Summary The amount and distribution of connective tissue in the swimming muscle of cod (Gadus mor... more Summary The amount and distribution of connective tissue in the swimming muscle of cod (Gadus morhua) have been determined. By biochemical analysis, the collagen was found to make up 1,5 % of the total protein content. Measured by light microscopical morphometric analysis, the areal fraction of the connective tissue elements was found to be 3,0 % of the total muscle area. The areal fraction of myocommatal connective tissue mentioned above was found to be 2.3 %. The thickness of the endomysial sheath was calculated by morphometry based on electron microscopy, and was found to be 0.30 and 0.16 μ for red and white fibres, respectively. The areal fraction of the endomysial sheaths was 2.3 % in red muscle and 0.5% in white muscle. The endomysial sheaths make up 25% of the total connective tissue in the swimming muscles. These sheaths influence the binding properties of fish muscle products.
The vascular supply of red, intermediate and white fibres in the axial muscle of axolotl (Ambysto... more The vascular supply of red, intermediate and white fibres in the axial muscle of axolotl (Ambystoma mexicanum Shaw) was visualized with Indian ink-injections and quantified with morphometrical methods on semithin sections. Red fibres were surrounded by 1.4 ± 0.6 capillaries (mean + SD), the intermediate fibres by 1.2 ± 0.9 capillaries and white fibres by 0.3 ± 0.6 capillaries. The mean vascularized surface area per unit volume of fibre was 0.0159, and 0.0068 and 0.0007 (μm2/μm3) for red, intermediate and white fibres, respectively. A unit volume of mitochondria within each type of fibre was supplied by 0.15, 0.17 and 0.08 μm2 vascularized surface for red, intermediate and white fibres, respectively. This indicates that there exist a good balance between oxygen demand represented by mitochondrial content and oxygen supply represented by the vascularized surface.
In aquaculture the risk of transmission of fish pathogens via eggs is reduced by disinfection in ... more In aquaculture the risk of transmission of fish pathogens via eggs is reduced by disinfection in ozonated seawater, but this treatment may delay or reduce hatching. The objective of this study was to investigate the tolerance of Atlantic cod, turbot and Atlantic halibut eggs to ...
Atlantic salmon (Salmo salar L.) fry were reared on a fishmeal-based diet with three different le... more Atlantic salmon (Salmo salar L.) fry were reared on a fishmeal-based diet with three different levels of vitamin D3 (0.2, 5 and 57 mg vitamin D3 kg–1 feed, ww) from first-feeding for 14 weeks. No significant differences were recorded in weight, length, specific growth rate, mortality, or kidney calcium concentration between the different dietary groups. No skeletal malformations or histopathological changes were recorded in any of the dietary groups. These results suggest Atlantic salmon fry to be highly tolerant of megadoses of vitamin D3 over a limited period of time.
The teleost backbone consists of amphicoelous vertebrae and intervertebral ligaments, both of whi... more The teleost backbone consists of amphicoelous vertebrae and intervertebral ligaments, both of which include notochord-derived structures. On the basis of a sequential developmental study of the vertebral column of Atlantic salmon (Salmo salar L.) from the egg stage up to early fry stage (300–2500 day-degrees) we show that the vertebral body consists of four layers or compartments, two of which are formed through mineralization of preformed collagenous tissue (the notochordal sheath and the intervertebral ligament) and two of which are formed through ossification. The three inner layers have ordered lamellar collagen matrixes, which alternate perpendicularly from layer to layer, whereas the outer layer consists of cancellous bone with a woven matrix. The bone layers also differ in osteocyte content. In this study we describe the structural details of the layers, and their modes of formation. The results are compared with previous descriptions, and possible phylogenetic implications are discussed.
The fine structure of the somatic muscles and their attachment to the cuticle in the pyenogonids ... more The fine structure of the somatic muscles and their attachment to the cuticle in the pyenogonids Nymphon (Chaetonymphon) macronyx G. O. Sars and Boreonymphon cf. abyssorum (Norman) is described. The muscles possess characteristics which are typical of arthropod slow muscle fibers: relatively long sarcomeres, a mean A‐band length of about 6 μm and a ratio of thin to thick contractile filaments of 4:1. The sarcotubular system consists of distinct t‐tubules, an irregular SR part and randomly distributed dyads and triads, the muscles are attached to the cuticle by specialized epidermal cells containing microtubules extending from the cuticular to the muscular side. The myoepidermal and epidermal‐cuticular junctions are described.
We performed a sequential morphological and molecular biological study of the development of the ... more We performed a sequential morphological and molecular biological study of the development of the vertebral bodies in Atlantic salmon (Salmo salar L.). Mineralization starts in separate bony elements which fuse to form complete segmental rings within the notochord sheath. The nucleation and growth of hydroxyapatite crystals in both the lamellar type II collagen matrix of the notochord sheath and the lamellar type I collagen matrix derived from the sclerotome, were highly similar. In both matrices the hydroxyapatite crystals nucleate and accrete on the surface of the collagen fibrils rather than inside the fibrils, a process that may be controlled by a template imposed by the collagen fibrils. Apatite crystal growth starts with the formation of small plate-like structures, about 5 nm thick, that gradually grow and aggregate to form extensive multi-branched crystal arborizations, resembling dendritic growth. The hydroxyapatite crystals are always oriented parallel to the long axis of the collagen fibrils, and the lamellar collagen matrices provide oriented support for crystal growth. We demonstrate here for the first time by means of synchroton radiation based on X-ray diffraction that the chordacentra contain hydroxyapatite. We employed quantitative real-time PCR to study the expression of key signalling molecule transcripts expressed in the cellular core of the notochord. The results indicate that the notochord not only produces and maintains the notochord sheath but also expresses factors known to regulate skeletogenesis: sonic hedgehog (shh), indian hedgehog homolog b (ihhb), parathyroid hormone 1 receptor (pth1r) and transforming growth factor beta 1 (tgfb1). In conclusion, our study provides evidence for the process of vertebral body development in teleost fishes, which is initially orchestrated by the notochord.
: This study describes the long‐term effects of surgical ablation of the pineal gland on the spi... more : This study describes the long‐term effects of surgical ablation of the pineal gland on the spine of 3‐yr‐old Atlantic salmon (Salmo salar L.) with a mean weight of 3.2 kg. Radiographic examinations showed that 82% of the pinealectomized fish developed marked lateral (scoliosis) and dorso‐ventral spinal curvatures. The proportions of the individual vertebral bodies and their mechanical properties were also altered. The stiffness, yield limit and resilience of the vertebral bodies, as measured by compression in the cranio‐caudal direction, were significantly lower in the pinealectomized than in the sham‐pinealectomized group. Calcium, phosphorous and total mineral content of the vertebral bodies were also significantly lower in the pinealectomized fish, while these parameters were similar in scales in the two groups. Alterations of the spinal curve accompanied by changes in the proportions, mechanical strength and mineral content of the vertebral bodies of the pinealectomized salmon indicate that melatonin has several functions related to vertebral bone growth. As the lesions found in salmon are similar to the spinal malformations observed in avian species and mammals after pinealectomy, this study strengthens the hypothesis of a phylogenetically conserved function of the pineal gland related to skeletal development.
Summary The amount and distribution of connective tissue in the swimming muscle of cod (Gadus mor... more Summary The amount and distribution of connective tissue in the swimming muscle of cod (Gadus morhua) have been determined. By biochemical analysis, the collagen was found to make up 1,5 % of the total protein content. Measured by light microscopical morphometric analysis, the areal fraction of the connective tissue elements was found to be 3,0 % of the total muscle area. The areal fraction of myocommatal connective tissue mentioned above was found to be 2.3 %. The thickness of the endomysial sheath was calculated by morphometry based on electron microscopy, and was found to be 0.30 and 0.16 μ for red and white fibres, respectively. The areal fraction of the endomysial sheaths was 2.3 % in red muscle and 0.5% in white muscle. The endomysial sheaths make up 25% of the total connective tissue in the swimming muscles. These sheaths influence the binding properties of fish muscle products.
The vascular supply of red, intermediate and white fibres in the axial muscle of axolotl (Ambysto... more The vascular supply of red, intermediate and white fibres in the axial muscle of axolotl (Ambystoma mexicanum Shaw) was visualized with Indian ink-injections and quantified with morphometrical methods on semithin sections. Red fibres were surrounded by 1.4 ± 0.6 capillaries (mean + SD), the intermediate fibres by 1.2 ± 0.9 capillaries and white fibres by 0.3 ± 0.6 capillaries. The mean vascularized surface area per unit volume of fibre was 0.0159, and 0.0068 and 0.0007 (μm2/μm3) for red, intermediate and white fibres, respectively. A unit volume of mitochondria within each type of fibre was supplied by 0.15, 0.17 and 0.08 μm2 vascularized surface for red, intermediate and white fibres, respectively. This indicates that there exist a good balance between oxygen demand represented by mitochondrial content and oxygen supply represented by the vascularized surface.
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Papers by Geir Totland