Anna Wargelius - Academia.edu (original) (raw)
Papers by Anna Wargelius
This study shows that exposure to continuous light induces regional differences in growth in the ... more This study shows that exposure to continuous light induces regional differences in growth in the vertebral column of Atlantic salmon under-yearling post-smolts reared in seawater cages. Exposure to continuous light during the period from January to the summer solstice (June) generally produced significantly larger fish than those reared under natural light. Until April, however, the fish exposed to continuous
PloS one, 2014
Understanding the biological function behind key proteins is of great concern in Atlantic salmon,... more Understanding the biological function behind key proteins is of great concern in Atlantic salmon, both due to a high commercial importance and an interesting life history. Until recently, functional studies in salmonids appeared to be difficult. However, the recent discovery of targeted mutagenesis using the CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/CRISPR-associated) system enables performing functional studies in Atlantic salmon to a great extent. We used the CRISPR/Cas9 system to target two genes involved in pigmentation, tyrosinase (tyr) and solute carrier family 45, member 2 (slc45a2). Embryos were assayed for mutation rates at the 17 somite stage, where 40 and 22% of all injected embryos showed a high degree of mutation induction for slc45a2 and tyr, respectively. At hatching this mutation frequency was also visible for both targeted genes, displaying a graded phenotype ranging from complete lack of pigmentation to partial loss and normal pigmentation. C...
Biochemical and biophysical research communications, Jan 19, 2003
Homologues of the homeobox genes sine oculis (so) and eyeless (ey) are important regulators of ey... more Homologues of the homeobox genes sine oculis (so) and eyeless (ey) are important regulators of eye development in both vertebrates and invertebrates. A Drosophila paralogue of so, optix, is an orthologue of the vertebrate Six3 gene family. Our analysis of zebrafish six3.1 demonstrated retinal expression in two separate cell layers and the ciliary marginal zone. This pattern is consistent with the observations of Six3 in other vertebrates and indicates functional conservation. We studied the 5(') flanking region of six3.1 and showed that separate enhancing elements are required for expression at different stages of eye development. This analysis also revealed specific binding of zebrafish Pax6.1 protein to an element required for six3.1 expression in ganglion cells. Furthermore, an enhancement of six3.1 transcription by Pax6.1 was observed by co-injection experiments. These results provide evidence for a direct regulatory interaction between vertebrate Pax6 and Six3 genes in eye ...
Gene, Jan 24, 2006
Paired box transcription factor 7 (Pax-7) cDNA was isolated from the skeletal muscle and brain of... more Paired box transcription factor 7 (Pax-7) cDNA was isolated from the skeletal muscle and brain of alevin and adult stages of Atlantic salmon, identifying 10 variants categorised as novel or established insertions (ins) or deletions (del). Two putative Pax-7 paralogs were identified (denoted Pax-7alpha and Pax-7beta) on the basis of the length and sequences of intron 3 (218 and 248 bp) and versions of ins1 and ins2. Pax-7beta contained a threonine variant of ins1 (GQY[T]GPEYVYCGT), and a shortened variant of ins2 (GEAS). Pattern identification revealed the threonine variant of ins1 includes a potential phosphorylation site (casein kinase II). Thus, the tetraploid Atlantic salmon genome appears to contain at least two putative copies and multiple splice variants of Pax-7. In situ hybridisation localised Pax-7 to mononuclear cells in the fast muscle of adult Atlantic salmon, while quantitative real-time PCR showed Pax-7alpha to be more highly expressed in brain than in skeletal muscle.
Journal of Experimental Biology, 2009
In order to study the effects of photoperiod on fish bone, Atlantic salmon (Salmo salar L.) were ... more In order to study the effects of photoperiod on fish bone, Atlantic salmon (Salmo salar L.) were exposed to two light regimes (natural and continuous light) from January until June. During the experimental period, several parameters related to the inorganic (minerals) and organic (osteoid) phases were measured. Changes in the organic phase were related to mechanical strength (yield-load) and the expression of the genes sonic hedgehog (shh) and collagen type I alpha 2 (col I).
Journal of Experimental Biology, 2010
Atlantic salmon (Salmo salar L.) vertebral bone displays plasticity in structure, osteoid secreti... more 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 alpha1, 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 alpha1, which may be involved in the regulatory pathway leading to structural adaptation of the vertebral architecture.
Journal of Fish Biology, 2004
The effect of egg vitamin A (VA) status and egg incubation temperature on the development of spin... more The effect of egg vitamin A (VA) status and egg incubation temperature on the development of spinal disorders was investigated in Atlantic salmon Salmo salar fry. Atlantic salmon eggs were sorted into two groups with high VA (3Á3 AE 0Á1 mg retinol g À1 dry mass) and low VA (2Á2 AE 0Á3 mg retinol g À1 dry mass) status before fertilization and incubated at high (14 C) or low (8 C) temperature from 133 day degrees until the onset of feeding. High egg incubation temperatures increased the concentration of retinol in the eggs: the high VA and high temperature group displayed a significantly higher retinol concentration than the high VA and low temperature group (P ¼ 0Á001). After hatching, all experimental groups increased their retinol concentration. The source of the increased retinol levels was probably retinal, although astaxanthin may also be a VA precursor after hatching. Atlantic salmon fry incubated at high temperatures had increased amounts of notochord tissue. When measuring morphogenic activity in the notochord using the expression of sonic hedgehog (shh, mRNA), however, no significant difference was found between the experimental groups. No clear effect of VA status or incubation temperature could be found on the formation of the early vertebral column although Atlantic salmon fry incubated at low temperatures had less regular constrictions of the prospective vertebral column than fry incubated at high temperatures.
General and Comparative Endocrinology, 2006
Aiming to elucidate the role of GH and IGF-I with regard to vertebral and white muscle growth, ge... more Aiming to elucidate the role of GH and IGF-I with regard to vertebral and white muscle growth, gene expression of the GH and IGF-I receptors (ghr and igf-Ir, respectively) and local IGF-I (igf-I) were analyzed during spring growth (January–June) in Atlantic salmon postsmolts. One group of fish was reared under natural light (NL), while one group was reared under continuous
Journal of Applied Ichthyology, 2010
The aim of the present study was to examine if dietary inclusion of vegetable lipids (VL) and pro... more The aim of the present study was to examine if dietary inclusion of vegetable lipids (VL) and proteins (VP) influenced markers of bone health in Atlantic salmon. Triplicate groups were fed one of four different diets; 100% fish protein (FP) and fish lipids (FL) (FPFL), 80% VP and 35% VL (80VP35VL), 40% VP and 70% VL (40VP70VL), or 80% VP and 70% VL (80VP70VL) for 12 months on-growth in sea water. Fish were analyzed for vertebral bone mineralization (mineral content, as % of bone dry weight), vertebral deformities (radiology), vertebral bone mRNA expression of factors involved in mineralization (bone gla protein, bgp) and growth regulation (igf-I and growth hormone receptor), as well as plasma vitamin D metabolites. The fish grew from 0.35 to 4 kg during the experimental period. At the end of the experiment, significantly lower prevalence of fish with one or more deformed vertebrae was observed in the 80VP70VL group (11%) compared to the other groups (33-43%). There was a significant higher relative expression of igf-I mRNA in vertebral bone of fish fed the 80VP70VL diet compared to control fish (FPFL), while the other genes studied were unaffected. Elevated plasma 25-hydroxyvitamin D 3 recorded in the marine feed group is discussed as a predictor for later development of bone deformities. In conclusion, the present study shows that high inclusion levels of vegetable lipids and proteins may have a positive effect on bone health in Atlantic salmon postsmolts.
Journal of Applied Ichthyology, 2010
Vertebral body compression is a common problem in commercial farming of Atlantic salmon. Although... more Vertebral body compression is a common problem in commercial farming of Atlantic salmon. Although risk factors, such as vaccination and malnutrition, have been identified, the etiology is largely unknown. Histological studies of Atlantic salmon have shown that in a compressed deformity (platyspondyly) the length of the compact bone is reduced while the notochord start to form atypical chrondrogenic structures. In mammals, similar remodeling activities have been linked to inflammatory processes in the tissue. Hence, we wanted to investigate whether the compressed vertebrae in Atlantic salmon showed presence of local (IL-1b, TNF-a1), systemic (IgM) and chronic (MMP-13, MMP-9) immune responses (measured with quantitative PCR). Unvaccinated groups of Atlantic salmon that would later develop high or low prevalence of vertebral compression during on-growth in seawater were sampled at seawater transfer, and 3 and 6 weeks after seawater transfer. In addition, compressed and normal vertebrae from the high deformity prevalence group were sampled 44 weeks after transfer to seawater. MMP-13 was significantly up-regulated in the group that developed a high prevalence of deformity, and also significantly up-regulated in compressed vertebrae, 44 weeks after seawater transfer. In compressed vertebrae, MMP-13 was equally up-regulated in the notochord, compact bone and trabecular bone. The results of the present study suggest that MMP-13 may serve as an early indicator for bone remodeling which may lead to vertebral compression, and that there is a relationship between the development of vertebral compression and increased remodeling activities in farmed Atlantic salmon.
General and Comparative Endocrinology, 2005
Growth hormone (GH) and insulin-like growth factor-I (IGF-I) play major roles in the endocrine re... more Growth hormone (GH) and insulin-like growth factor-I (IGF-I) play major roles in the endocrine regulation of Wsh growth, but their interdependency and mode of action has not been well elucidated. The GH-IGF-I system is essential for normal vertebral growth in mouse, but this has not been studied in Wsh. To study the interplay between GH, IGF-I, and their receptors, postsmolt Atlantic salmon were studied during spring growth (January-June 2003). From January to June, Wsh were sampled regularly for plasma and vertebral bone. The vertebra was collected from the same anterior-posterior position. The growth hormone receptor (ghr) (There is no determined nomenclature of salmon genes but we stick to the nomenclature which is consequent for zebraWsh, where all gene names are named with small letters and in italic.) expression in the vertebrae peaked in the end of February coinciding with high levels of plasma GH and IGF-I, and an increase of vertebral growth rate. From April to June, plasma IGF-I levels decreased together with ghr expression in the vertebrae, while plasma GH did not decrease. In May and June, expression of the igf-I receptor (igf-Ir) increased 4-to 5-fold, which coincided with an increase in bone density. The changes seen in gene expression of the IGF-I and GH receptors suggest that these hormones are involved in vertebral growth and bone density.
Development Genes and Evolution, 2005
In several terrestrial vertebrates, heat shock (HS) during somitogenesis causes vertebral deformi... more In several terrestrial vertebrates, heat shock (HS) during somitogenesis causes vertebral deformities. To determine if vertebral deformities can occur due to sudden temperature changes during early development in fish, Atlantic salmon embryos were HS treated during somitogenesis. Ten months later these individuals displayed a high prevalence of caudal vertebral column condensations (27-34%). The defects were located caudally of the abdominal cavity, displaying an even distribution in this region independent of time of HS. To determine if HS disturbed vertebral development during somitogenesis, two genes coding for markers of skeletal development were identified, namely, the secreted protein Shh (Sashh) and the transcription factor Twist (Satwist). These proteins are involved in the proliferation and specification of presumptive skeletal cells (sclerotome) in vertebrates. The spatial expression pattern of sashh and satwist in salmon indicated a functional conservation of these proteins. Furthermore, HS embryos displayed expressional disturbance in both sashh and satwist, indicating an effect of HS on sclerotomal cell patterning. However, the HS-protecting ability in embryos seems to be individually regulated because reduction in gene expression was not detected at all stages; in addition, HS did not induce somitic disturbance and vertebral deformity in all embryos.
Cell and Tissue Research, 2011
The notochord functions as the midline structural element of all vertebrate embryos, and allows m... more The notochord functions as the midline structural element of all vertebrate embryos, and allows movement and growth at early developmental stages. Moreover, during embryonic development, notochord cells produce secreted factors that provide positional and fate information to a broad variety of cells within adjacent tissues, for instance those of the vertebrae, central nervous system and somites. Due to the large size of the embryo, the salmon notochord is useful to study as a model for exploring notochord development. To investigate factors that might be involved in notochord development, a normalized cDNA library was constructed from a mix of notochords from ∼500 to ∼800 day°. From the 1968 Sanger-sequenced transcripts, 22 genes were identified to be predominantly expressed in the notochord compared to other organs of salmon. Twelve of these genes were found to show expressional regulation around mineralization of the notochord sheath; 11 genes were up-regulated and one gene was down-regulated. Two genes were found to be specifically expressed in the notochord; these genes showed similarity to vimentin (acc. no GT297094) and elastin (acc. no GT297478). In-situ results showed that the vimentin- like transcript was expressed in both chordocytes and chordoblasts, whereas the elastin- like transcript was uniquely expressed in the chordoblasts lining the notochordal sheath. In salmon aquaculture, vertebral deformities are a common problem, and some malformations have been linked to the notochord. The expression of identified transcripts provides further insight into processes taking place in the developing notochord, prior to and during the early mineralization period.
Aquaculture, 2007
Atlantic salmon (Salmo salar) rely on changes in photoperiod for the synchronization of the devel... more Atlantic salmon (Salmo salar) rely on changes in photoperiod for the synchronization of the developmental events constituting the parr-smolt transformation. In the absence of photoperiod cues, parr-smolt transformation is incomplete, and such 'pseudo-smolts' normally fail to adapt to seawater. The present study addresses the endocrine and molecular mechanisms controlling the development of hypo-osmoregulatory ability and how artificial photoperiod can disrupt these changes. Juvenile Atlantic salmon reared under constant light (LL) from first feeding, were separated into two groups, and exposed to either LL or simulated natural photoperiod (LDN) from October, eight months prior to the expected completion of smoltification. Juveniles reared on LL grew well, but failed to show the smolt-related reduction in condition factor in spring. Gill mRNA levels of Na + , K + -ATPase (NKA) isoform α1a decreased in LDN fish through completion of parr-smolt transformation, while levels remained unchanged in the LL group. In contrast, α1b expression increased 6-fold in the LDN group between February and May, again with no change in the LL group. Further, Na + , K + , 2Cl − co-transporter (NKCC) showed a transient increase in expression in smolts on LDN between February and May, while no changes in mRNA levels were seen in juveniles under LL. Consequently, gill NKA activity and NKA α and NKCC protein abundance were significantly lower in juveniles on LL than in smolts on LDN. LL fish in spring had lower circulating levels of thyroid hormones (THs), growth hormone (GH) and cortisol. Gill GH-receptor mRNA levels, determined by quantitative PCR, were less than 50% of controls. In contrast, circulating levels of IGF-1 and gill IGF-1 receptor expression, were comparable to controls. Our findings show that continuous light prevents the completion of parr-smolt transformation at a very basic level, disrupting the natural up-regulation of key elements of the endocrine system involved in the regulation of the parr-smolt transformation, and consequently inhibiting the smoltification-related increase in expression, abundance and activity of gill ion transport proteins.
Aquaculture, 2005
This study shows that exposure to continuous light induces regional differences in growth in the ... more This study shows that exposure to continuous light induces regional differences in growth in the vertebral column of Atlantic salmon under-yearling post-smolts reared in seawater cages. Exposure to continuous light during the period from January to the summer solstice (June) generally produced significantly larger fish than those reared under natural light. Until April, however, the fish exposed to continuous light grew more slowly, as reflected in the vertebral column by decreased growth in the truncal vertebrae, while the growth of the tail vertebrae was similar in the two groups. From April to June the fish exposed to continuous light displayed the fastest growth, with a higher growth rate in the vertebrae of the trunk than among fish reared under natural light. The mineral rate and mechanical strength of the vertebrae at the summer solstice was significantly lower in fish exposed to continuous light. Our results suggest that the growth of different regions of the vertebral column of salmon may be regulated partly independently, and that mineralisation is also affected during fast growth. D
Molecular Reproduction and Development, 2015
Fish in use in aquaculture display large variation in gamete biology. To reach better understandi... more Fish in use in aquaculture display large variation in gamete biology. To reach better understanding around this issue, this study aims at identifying if species specific "egg life history traits" can be hidden in the unfertilized egg. This was done by investigating egg transcriptome differences between Atlantic salmon and Atlantic cod. Salmon and cod eggs were selected due to their largely differencing phenotypes. An oligo microarray analysis was performed on ovulated eggs from cod (n = 8) and salmon (n = 7). The arrays were normalized to a similar spectrum for both arrays. Both arrays were re-annotated with SWISS-Prot and KEGG genes to retrieve an official gene symbol and an orthologous KEGG annotation, in salmon and cod arrays this represented 14,009 and 7,437 genes respectively. The probe linked to the highest gene expression for that particular KEGG annotation was used to compare expression between species. Differential expression was calculated for genes that had an annotation with score >300, resulting in a total of 2,457 KEGG annotations (genes) being differently expressed between the species (FD > 2). This analysis revealed that immune, signal transduction and excretory related pathways were overrepresented in salmon compared to cod. The most overrepresented pathways in cod were related to regulation of genetic information processing and metabolism. To conclude this analysis clearly point at some distinct transcriptome repertoires for cod and salmon and that these differences may explain some of the species-specific biological features for salmon and cod eggs. Mol. Reprod. Dev. 82: 397-404, 2015. © 2015 Wiley Periodicals, Inc.
This study shows that exposure to continuous light induces regional differences in growth in the ... more This study shows that exposure to continuous light induces regional differences in growth in the vertebral column of Atlantic salmon under-yearling post-smolts reared in seawater cages. Exposure to continuous light during the period from January to the summer solstice (June) generally produced significantly larger fish than those reared under natural light. Until April, however, the fish exposed to continuous
PloS one, 2014
Understanding the biological function behind key proteins is of great concern in Atlantic salmon,... more Understanding the biological function behind key proteins is of great concern in Atlantic salmon, both due to a high commercial importance and an interesting life history. Until recently, functional studies in salmonids appeared to be difficult. However, the recent discovery of targeted mutagenesis using the CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/CRISPR-associated) system enables performing functional studies in Atlantic salmon to a great extent. We used the CRISPR/Cas9 system to target two genes involved in pigmentation, tyrosinase (tyr) and solute carrier family 45, member 2 (slc45a2). Embryos were assayed for mutation rates at the 17 somite stage, where 40 and 22% of all injected embryos showed a high degree of mutation induction for slc45a2 and tyr, respectively. At hatching this mutation frequency was also visible for both targeted genes, displaying a graded phenotype ranging from complete lack of pigmentation to partial loss and normal pigmentation. C...
Biochemical and biophysical research communications, Jan 19, 2003
Homologues of the homeobox genes sine oculis (so) and eyeless (ey) are important regulators of ey... more Homologues of the homeobox genes sine oculis (so) and eyeless (ey) are important regulators of eye development in both vertebrates and invertebrates. A Drosophila paralogue of so, optix, is an orthologue of the vertebrate Six3 gene family. Our analysis of zebrafish six3.1 demonstrated retinal expression in two separate cell layers and the ciliary marginal zone. This pattern is consistent with the observations of Six3 in other vertebrates and indicates functional conservation. We studied the 5(') flanking region of six3.1 and showed that separate enhancing elements are required for expression at different stages of eye development. This analysis also revealed specific binding of zebrafish Pax6.1 protein to an element required for six3.1 expression in ganglion cells. Furthermore, an enhancement of six3.1 transcription by Pax6.1 was observed by co-injection experiments. These results provide evidence for a direct regulatory interaction between vertebrate Pax6 and Six3 genes in eye ...
Gene, Jan 24, 2006
Paired box transcription factor 7 (Pax-7) cDNA was isolated from the skeletal muscle and brain of... more Paired box transcription factor 7 (Pax-7) cDNA was isolated from the skeletal muscle and brain of alevin and adult stages of Atlantic salmon, identifying 10 variants categorised as novel or established insertions (ins) or deletions (del). Two putative Pax-7 paralogs were identified (denoted Pax-7alpha and Pax-7beta) on the basis of the length and sequences of intron 3 (218 and 248 bp) and versions of ins1 and ins2. Pax-7beta contained a threonine variant of ins1 (GQY[T]GPEYVYCGT), and a shortened variant of ins2 (GEAS). Pattern identification revealed the threonine variant of ins1 includes a potential phosphorylation site (casein kinase II). Thus, the tetraploid Atlantic salmon genome appears to contain at least two putative copies and multiple splice variants of Pax-7. In situ hybridisation localised Pax-7 to mononuclear cells in the fast muscle of adult Atlantic salmon, while quantitative real-time PCR showed Pax-7alpha to be more highly expressed in brain than in skeletal muscle.
Journal of Experimental Biology, 2009
In order to study the effects of photoperiod on fish bone, Atlantic salmon (Salmo salar L.) were ... more In order to study the effects of photoperiod on fish bone, Atlantic salmon (Salmo salar L.) were exposed to two light regimes (natural and continuous light) from January until June. During the experimental period, several parameters related to the inorganic (minerals) and organic (osteoid) phases were measured. Changes in the organic phase were related to mechanical strength (yield-load) and the expression of the genes sonic hedgehog (shh) and collagen type I alpha 2 (col I).
Journal of Experimental Biology, 2010
Atlantic salmon (Salmo salar L.) vertebral bone displays plasticity in structure, osteoid secreti... more 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 alpha1, 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 alpha1, which may be involved in the regulatory pathway leading to structural adaptation of the vertebral architecture.
Journal of Fish Biology, 2004
The effect of egg vitamin A (VA) status and egg incubation temperature on the development of spin... more The effect of egg vitamin A (VA) status and egg incubation temperature on the development of spinal disorders was investigated in Atlantic salmon Salmo salar fry. Atlantic salmon eggs were sorted into two groups with high VA (3Á3 AE 0Á1 mg retinol g À1 dry mass) and low VA (2Á2 AE 0Á3 mg retinol g À1 dry mass) status before fertilization and incubated at high (14 C) or low (8 C) temperature from 133 day degrees until the onset of feeding. High egg incubation temperatures increased the concentration of retinol in the eggs: the high VA and high temperature group displayed a significantly higher retinol concentration than the high VA and low temperature group (P ¼ 0Á001). After hatching, all experimental groups increased their retinol concentration. The source of the increased retinol levels was probably retinal, although astaxanthin may also be a VA precursor after hatching. Atlantic salmon fry incubated at high temperatures had increased amounts of notochord tissue. When measuring morphogenic activity in the notochord using the expression of sonic hedgehog (shh, mRNA), however, no significant difference was found between the experimental groups. No clear effect of VA status or incubation temperature could be found on the formation of the early vertebral column although Atlantic salmon fry incubated at low temperatures had less regular constrictions of the prospective vertebral column than fry incubated at high temperatures.
General and Comparative Endocrinology, 2006
Aiming to elucidate the role of GH and IGF-I with regard to vertebral and white muscle growth, ge... more Aiming to elucidate the role of GH and IGF-I with regard to vertebral and white muscle growth, gene expression of the GH and IGF-I receptors (ghr and igf-Ir, respectively) and local IGF-I (igf-I) were analyzed during spring growth (January–June) in Atlantic salmon postsmolts. One group of fish was reared under natural light (NL), while one group was reared under continuous
Journal of Applied Ichthyology, 2010
The aim of the present study was to examine if dietary inclusion of vegetable lipids (VL) and pro... more The aim of the present study was to examine if dietary inclusion of vegetable lipids (VL) and proteins (VP) influenced markers of bone health in Atlantic salmon. Triplicate groups were fed one of four different diets; 100% fish protein (FP) and fish lipids (FL) (FPFL), 80% VP and 35% VL (80VP35VL), 40% VP and 70% VL (40VP70VL), or 80% VP and 70% VL (80VP70VL) for 12 months on-growth in sea water. Fish were analyzed for vertebral bone mineralization (mineral content, as % of bone dry weight), vertebral deformities (radiology), vertebral bone mRNA expression of factors involved in mineralization (bone gla protein, bgp) and growth regulation (igf-I and growth hormone receptor), as well as plasma vitamin D metabolites. The fish grew from 0.35 to 4 kg during the experimental period. At the end of the experiment, significantly lower prevalence of fish with one or more deformed vertebrae was observed in the 80VP70VL group (11%) compared to the other groups (33-43%). There was a significant higher relative expression of igf-I mRNA in vertebral bone of fish fed the 80VP70VL diet compared to control fish (FPFL), while the other genes studied were unaffected. Elevated plasma 25-hydroxyvitamin D 3 recorded in the marine feed group is discussed as a predictor for later development of bone deformities. In conclusion, the present study shows that high inclusion levels of vegetable lipids and proteins may have a positive effect on bone health in Atlantic salmon postsmolts.
Journal of Applied Ichthyology, 2010
Vertebral body compression is a common problem in commercial farming of Atlantic salmon. Although... more Vertebral body compression is a common problem in commercial farming of Atlantic salmon. Although risk factors, such as vaccination and malnutrition, have been identified, the etiology is largely unknown. Histological studies of Atlantic salmon have shown that in a compressed deformity (platyspondyly) the length of the compact bone is reduced while the notochord start to form atypical chrondrogenic structures. In mammals, similar remodeling activities have been linked to inflammatory processes in the tissue. Hence, we wanted to investigate whether the compressed vertebrae in Atlantic salmon showed presence of local (IL-1b, TNF-a1), systemic (IgM) and chronic (MMP-13, MMP-9) immune responses (measured with quantitative PCR). Unvaccinated groups of Atlantic salmon that would later develop high or low prevalence of vertebral compression during on-growth in seawater were sampled at seawater transfer, and 3 and 6 weeks after seawater transfer. In addition, compressed and normal vertebrae from the high deformity prevalence group were sampled 44 weeks after transfer to seawater. MMP-13 was significantly up-regulated in the group that developed a high prevalence of deformity, and also significantly up-regulated in compressed vertebrae, 44 weeks after seawater transfer. In compressed vertebrae, MMP-13 was equally up-regulated in the notochord, compact bone and trabecular bone. The results of the present study suggest that MMP-13 may serve as an early indicator for bone remodeling which may lead to vertebral compression, and that there is a relationship between the development of vertebral compression and increased remodeling activities in farmed Atlantic salmon.
General and Comparative Endocrinology, 2005
Growth hormone (GH) and insulin-like growth factor-I (IGF-I) play major roles in the endocrine re... more Growth hormone (GH) and insulin-like growth factor-I (IGF-I) play major roles in the endocrine regulation of Wsh growth, but their interdependency and mode of action has not been well elucidated. The GH-IGF-I system is essential for normal vertebral growth in mouse, but this has not been studied in Wsh. To study the interplay between GH, IGF-I, and their receptors, postsmolt Atlantic salmon were studied during spring growth (January-June 2003). From January to June, Wsh were sampled regularly for plasma and vertebral bone. The vertebra was collected from the same anterior-posterior position. The growth hormone receptor (ghr) (There is no determined nomenclature of salmon genes but we stick to the nomenclature which is consequent for zebraWsh, where all gene names are named with small letters and in italic.) expression in the vertebrae peaked in the end of February coinciding with high levels of plasma GH and IGF-I, and an increase of vertebral growth rate. From April to June, plasma IGF-I levels decreased together with ghr expression in the vertebrae, while plasma GH did not decrease. In May and June, expression of the igf-I receptor (igf-Ir) increased 4-to 5-fold, which coincided with an increase in bone density. The changes seen in gene expression of the IGF-I and GH receptors suggest that these hormones are involved in vertebral growth and bone density.
Development Genes and Evolution, 2005
In several terrestrial vertebrates, heat shock (HS) during somitogenesis causes vertebral deformi... more In several terrestrial vertebrates, heat shock (HS) during somitogenesis causes vertebral deformities. To determine if vertebral deformities can occur due to sudden temperature changes during early development in fish, Atlantic salmon embryos were HS treated during somitogenesis. Ten months later these individuals displayed a high prevalence of caudal vertebral column condensations (27-34%). The defects were located caudally of the abdominal cavity, displaying an even distribution in this region independent of time of HS. To determine if HS disturbed vertebral development during somitogenesis, two genes coding for markers of skeletal development were identified, namely, the secreted protein Shh (Sashh) and the transcription factor Twist (Satwist). These proteins are involved in the proliferation and specification of presumptive skeletal cells (sclerotome) in vertebrates. The spatial expression pattern of sashh and satwist in salmon indicated a functional conservation of these proteins. Furthermore, HS embryos displayed expressional disturbance in both sashh and satwist, indicating an effect of HS on sclerotomal cell patterning. However, the HS-protecting ability in embryos seems to be individually regulated because reduction in gene expression was not detected at all stages; in addition, HS did not induce somitic disturbance and vertebral deformity in all embryos.
Cell and Tissue Research, 2011
The notochord functions as the midline structural element of all vertebrate embryos, and allows m... more The notochord functions as the midline structural element of all vertebrate embryos, and allows movement and growth at early developmental stages. Moreover, during embryonic development, notochord cells produce secreted factors that provide positional and fate information to a broad variety of cells within adjacent tissues, for instance those of the vertebrae, central nervous system and somites. Due to the large size of the embryo, the salmon notochord is useful to study as a model for exploring notochord development. To investigate factors that might be involved in notochord development, a normalized cDNA library was constructed from a mix of notochords from ∼500 to ∼800 day°. From the 1968 Sanger-sequenced transcripts, 22 genes were identified to be predominantly expressed in the notochord compared to other organs of salmon. Twelve of these genes were found to show expressional regulation around mineralization of the notochord sheath; 11 genes were up-regulated and one gene was down-regulated. Two genes were found to be specifically expressed in the notochord; these genes showed similarity to vimentin (acc. no GT297094) and elastin (acc. no GT297478). In-situ results showed that the vimentin- like transcript was expressed in both chordocytes and chordoblasts, whereas the elastin- like transcript was uniquely expressed in the chordoblasts lining the notochordal sheath. In salmon aquaculture, vertebral deformities are a common problem, and some malformations have been linked to the notochord. The expression of identified transcripts provides further insight into processes taking place in the developing notochord, prior to and during the early mineralization period.
Aquaculture, 2007
Atlantic salmon (Salmo salar) rely on changes in photoperiod for the synchronization of the devel... more Atlantic salmon (Salmo salar) rely on changes in photoperiod for the synchronization of the developmental events constituting the parr-smolt transformation. In the absence of photoperiod cues, parr-smolt transformation is incomplete, and such 'pseudo-smolts' normally fail to adapt to seawater. The present study addresses the endocrine and molecular mechanisms controlling the development of hypo-osmoregulatory ability and how artificial photoperiod can disrupt these changes. Juvenile Atlantic salmon reared under constant light (LL) from first feeding, were separated into two groups, and exposed to either LL or simulated natural photoperiod (LDN) from October, eight months prior to the expected completion of smoltification. Juveniles reared on LL grew well, but failed to show the smolt-related reduction in condition factor in spring. Gill mRNA levels of Na + , K + -ATPase (NKA) isoform α1a decreased in LDN fish through completion of parr-smolt transformation, while levels remained unchanged in the LL group. In contrast, α1b expression increased 6-fold in the LDN group between February and May, again with no change in the LL group. Further, Na + , K + , 2Cl − co-transporter (NKCC) showed a transient increase in expression in smolts on LDN between February and May, while no changes in mRNA levels were seen in juveniles under LL. Consequently, gill NKA activity and NKA α and NKCC protein abundance were significantly lower in juveniles on LL than in smolts on LDN. LL fish in spring had lower circulating levels of thyroid hormones (THs), growth hormone (GH) and cortisol. Gill GH-receptor mRNA levels, determined by quantitative PCR, were less than 50% of controls. In contrast, circulating levels of IGF-1 and gill IGF-1 receptor expression, were comparable to controls. Our findings show that continuous light prevents the completion of parr-smolt transformation at a very basic level, disrupting the natural up-regulation of key elements of the endocrine system involved in the regulation of the parr-smolt transformation, and consequently inhibiting the smoltification-related increase in expression, abundance and activity of gill ion transport proteins.
Aquaculture, 2005
This study shows that exposure to continuous light induces regional differences in growth in the ... more This study shows that exposure to continuous light induces regional differences in growth in the vertebral column of Atlantic salmon under-yearling post-smolts reared in seawater cages. Exposure to continuous light during the period from January to the summer solstice (June) generally produced significantly larger fish than those reared under natural light. Until April, however, the fish exposed to continuous light grew more slowly, as reflected in the vertebral column by decreased growth in the truncal vertebrae, while the growth of the tail vertebrae was similar in the two groups. From April to June the fish exposed to continuous light displayed the fastest growth, with a higher growth rate in the vertebrae of the trunk than among fish reared under natural light. The mineral rate and mechanical strength of the vertebrae at the summer solstice was significantly lower in fish exposed to continuous light. Our results suggest that the growth of different regions of the vertebral column of salmon may be regulated partly independently, and that mineralisation is also affected during fast growth. D
Molecular Reproduction and Development, 2015
Fish in use in aquaculture display large variation in gamete biology. To reach better understandi... more Fish in use in aquaculture display large variation in gamete biology. To reach better understanding around this issue, this study aims at identifying if species specific "egg life history traits" can be hidden in the unfertilized egg. This was done by investigating egg transcriptome differences between Atlantic salmon and Atlantic cod. Salmon and cod eggs were selected due to their largely differencing phenotypes. An oligo microarray analysis was performed on ovulated eggs from cod (n = 8) and salmon (n = 7). The arrays were normalized to a similar spectrum for both arrays. Both arrays were re-annotated with SWISS-Prot and KEGG genes to retrieve an official gene symbol and an orthologous KEGG annotation, in salmon and cod arrays this represented 14,009 and 7,437 genes respectively. The probe linked to the highest gene expression for that particular KEGG annotation was used to compare expression between species. Differential expression was calculated for genes that had an annotation with score >300, resulting in a total of 2,457 KEGG annotations (genes) being differently expressed between the species (FD > 2). This analysis revealed that immune, signal transduction and excretory related pathways were overrepresented in salmon compared to cod. The most overrepresented pathways in cod were related to regulation of genetic information processing and metabolism. To conclude this analysis clearly point at some distinct transcriptome repertoires for cod and salmon and that these differences may explain some of the species-specific biological features for salmon and cod eggs. Mol. Reprod. Dev. 82: 397-404, 2015. © 2015 Wiley Periodicals, Inc.