Immune parameters in the intestine of wild and reared unvaccinated and vaccinated Atlantic salmon (Salmo salar L.)

Forming a barrier to the outside world, the gut mucosa faces the challenge of absorbing nutrients and fluids while initiating immune reactions towards potential pathogens. As a continuation to our previous publication focusing on the regional intestinal morphology in wild caught post smolt and spawning Atlantic salmon, we here investigate selected immune parameters and compare wild, reared unvaccinated and vaccinated post smolts.     

Sustained swimming increases the mineral content and osteocyte density of salmon vertebral bone

This study addresses the effects of increased mechanical load on the vertebral bone of post-smolt Atlantic salmon by forcing them to swim at controlled speeds. The fish swam continuously in four circular tanks for 9 weeks, two groups at 0.47 body lengths (bl) × s(-1) (non-exercised group) and two groups at 2 bl × s(-1) (exercised group), which is just below the limit for maximum sustained swimming speed in this species. Qualitative data concerning the vertebral structure were obtained from histology and electron microscopy, and quantitative data were based on histomorphometry, high-resolution X-ray micro-computed tomography images and analysis of bone mineral content, while the mechanical properties were tested by compression. Our key findings are that the bone matrix secreted during sustained swimming had significantly higher mineral content and mechanical strength, while no effect was detected on bone in vivo architecture. mRNA levels for two mineralization-related genes bgp and alp were significantly upregulated in the exercised fish, indicating promotion of mineralization. The osteocyte density of the lamellar bone of the amphicoel was also significantly higher in the exercised than non-exercised fish, while the osteocyte density in the cancellous bone was similar in the two groups. The vertebral osteocytes did not form a functional syncytium, which shows that salmon vertebral bone responds to mechanical loading in the absence of an extensive connecting syncytial network of osteocytic cell processes as found in mammals, indicating the existence of a different mechanosensing mechanism. The adaptive response to increased load is thus probably mediated by osteoblasts or bone lining cells, a system in which signal detection and response may be co-located. This study offers new insight into the teleost bone biology, and may have implications for maintaining acceptable welfare for farmed salmon.     

A peak in gh-receptor expression is associated with growth activation in Atlantic salmon vertebrae, while upregulation of igf-I receptor expression is related to increased bone density

Growth hormone (GH) and insulin-like growth factor-I (IGF-I) play major roles in the endocrine regulation of fish 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 fish. 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, fish 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 zebrafish, 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.     

Growth hormone and insulin-like growth factor-I act together and independently when regulating growth in vertebral and muscle tissue of atlantic salmon postsmolts

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 light (LL). Growth rate of fork length was higher in the LL group for a short period after onset of continuous light (LL: 0.50+/-0.02 mm day(-1), NL: 0.43+/-0.01 mm day(-1)) and for a longer period at the end of the experiment in June (LL: 1.18+/-0.06 mm day(-1), NL: 0.75+/-0.02 mm day(-1)). Likewise, growth rate in length of vertebra No. 40 in the LL group was higher than in the NL group the first period after onset of light (LL: 0.015+/-0.002 mm day(-1), NL: 0.008+/-0.001 mm day(-1)). Plasma GH levels peaked in late February and were higher in the LL group than in the NL group (LL: 7.27+/-0.61 ng ml(-1), NL: 2.60+/-0.50 ng ml(-1)), whereas plasma IGF-I levels peaked in early February and were unaffected by photoperiod. ghr expression was upregulated in late February in liver (12-fold), white muscle (6-fold) and vertebral tissue (3-fold) and higher in the LL group than in the NL group (2-fold) in vertebral tissue in late March. White muscle expression of igf-I and igf-Ir decreased from initial levels throughout the experiment. Hepatic gene expression of igf-I doubled in both groups in late February, followed by a 4-fold upregulation in June in the LL group only. Vertebral tissue expression of igf-I (4-fold) and igf-Ir (6-fold) increased in May and were unaffected by photoperiod. One exception was a smaller upregulation of igf-I (2-fold) in the LL group in early February. In conclusion, GH appears to have an initial role in stimulating vertebral growth, while IGF-I seems to stimulate growth during late spring. It is suggested that local IGF-I acts as a paracrine agent, evaluated from the concurrent upregulation of igf-I and igf-Ir. The upregulation of ghr in white muscle tissue, concurrent with a downregulation of muscle igf-I and igf-Ir, indicate that GH stimulated growth or metabolism independent of IGF-I.     

Experiences with iohexol (Omnipaque) at urography

In a prospective study of 547 pediatric intravenous pyelographies with a new non-ionic contrast medium (iohexol), only 5 (0.9%) minor reactions were observed. The higher price seems justified, and iohexol is strongly recommended in neonates as well as older children.     

Quantitative multigene FISH on breast carcinomas identifies der(1;16)(q10;p10) as an early event in luminal A tumors

In situ detection of genomic alterations in cancer provides information at the single cell level, making it possible to investigate genomic changes in cells in a tissue context. Such topological information is important when studying intratumor heterogeneity as well as alterations related to different steps in tumor progression. We developed a quantitative multigene fluorescence in situ hybridization (QM FISH) method to detect multiple genomic regions in single cells in complex tissues. As a “proof of principle” we applied the method to breast cancer samples to identify partners in whole arm (WA) translocations. WA gain of chromosome arm 1q and loss of chromosome arm 16q are among the most frequent genomic events in breast cancer. By designing five specific FISH probes based on breakpoint information from comparative genomic hybridization array (aCGH) profiles, we visualized chromosomal translocations in clinical samples at the single cell level. By analyzing aCGH data from 295 patients with breast carcinoma with known molecular subtype, we found concurrent WA gain of 1q and loss of 16q to be more frequent in luminal A tumors compared to other molecular subtypes. QM FISH applied to a subset of samples (n = 26) identified a derivative chromosome der(1;16)(q10;p10), a result of a centromere‐close translocation between chromosome arms 1q and 16p. In addition, we observed that the distribution of cells with the translocation varied from sample to sample, some had a homogenous cell population while others displayed intratumor heterogeneity with cell‐to‐cell variation. Finally, for one tumor with both preinvasive and invasive components, the fraction of cells with translocation was lower and more heterogeneous in the preinvasive tumor cells compared to the cells in the invasive component. © 2014 The Authors Genes, Chromosomes & Cancer Published by Wiley Periodicals, Inc.     

Pinealectomy induces malformation of the spine and reduces the mechanical strength of the vertebrae in Atlantic salmon, Salmo salar

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.     

Heads and tails: The notochord develops differently in the cranium and caudal fin of Atlantic Salmon (Salmo salar,L.)

While it is well known that the notochord of bony fishes changes over developmental time, less is known about how it varies across different body regions. In the development of the Atlantic salmon, Salmo salar L., cranial and caudal ends of the notochord are overlaid by the formation of the bony elements of the neurocranium and caudal fin, respectively. To investigate, we describe how the notochord of the cranium and caudal fin changes from embryo to spawning adult, using light microscopy, SEM, TEM, dissection, and CT scanning. The differences are dramatic. In contrast to the abdominal and caudal regions, at the ends of the notochord vertebrae never develop. While the cranial notochord builds a tapering, unsegmented cone of chordal bone, the urostylic notochordal sheath never ossifies: adjacent, irregular bony elements form from the endoskeleton of the caudal fin. As development progresses, two previously undescribed processes occur. First, the bony cone of the cranial notochord, and its internal chordocytes, are degraded by chordoclasts, an undescribed function of the clastic cell type. Second, the sheath of the urostylic notochord creates transverse septae that partly traverse the lumen in an irregular pattern. By the adult stage, the cranial notochord is gone. In contrast, the urostylic notochord in adults is robust, reinforced with septae, covered by irregularly shaped pieces of cellular bone, and capped with an opistural cartilage that develops from the sheath of the urostylic notochord. A previously undescribed muscle, with its origin on the opistural cartilage, inserts on the lepidotrich ventral to it.