Publications by authors named "Sigríður Guðmundsdóttir"

9 Publications

  • Page 1 of 1

Characterization of ranaviruses isolated from lumpfish L. in the North Atlantic area: proposal for a new ranavirus species (European North Atlantic Ranavirus).

J Gen Virol 2020 02 20;101(2):198-207. Epub 2019 Dec 20.

Technical University of Denmark, National Institute of Aquatic Resources, Aquatic Animal Health Unit, Kgs. Lyngby, Denmark.

The commercial production of lumpfish L. is expanding with the increased demand for their use as cleaner fish, to control sea-lice numbers, at marine Atlantic salmon L. aquaculture sites throughout Northern Europe. A new ranavirus has been isolated from lumpfish at multiple locations in the North Atlantic area. First isolated in 2014 in the Faroe Islands, the virus has subsequently been found in lumpfish from Iceland in 2015 and from Scotland and Ireland in 2016. The Icelandic lumpfish ranavirus has been characterized by immunofluorescent antibody test, optimal growth conditions and transmission electron microscopy. Partial sequences of the major capsid protein gene from 12 isolates showed 99.79-100% nt identity between the lumpfish ranaviruses. Complete genome sequencing from three of the isolates and phylogenetic analysis based on the concatenated 26 iridovirus core genes suggest these lumpfish ranavirus isolates form a distinct clade with ranaviruses from cod L. and turbot L. isolated in Denmark in 1979 and 1999, respectively. These data suggest that these viruses should be grouped together as a new ranavirus species, European North Atlantic Ranavirus, which encompasses ranaviruses isolated from marine fishes in European North Atlantic waters.
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http://dx.doi.org/10.1099/jgv.0.001377DOI Listing
February 2020

Longitudinal Change in Adolescent Bedtimes Measured by Self-Report and Actigraphy.

J Meas Phys Behav 2019 Dec;2(4):282-287

Center of Sport and Health Sciences, University of Iceland, Reykjavik, Iceland; Department of Sport and Physical Activity, Western Norway University of Applied Sciences, Bergen, Norway.

Introduction: Sleep is often quantified using self-report or actigraphy. Self-report is practical and less technically challenging, but prone to bias. We sought to determine whether these methods have comparable sensitivity to measure longitudinal changes in adolescent bedtimes.

Methods: We measured one week of free-living sleep with wrist actigraphy and usual bedtime on school nights and non-school nights with self-report questionnaire in 144 students at 15 y and 17 y.

Results: Self-reported and actigraphy-measured bedtimes were correlated with one another at 15 y and 17 y ( < .001), but reported bedtime was consistently earlier (>30 minutes, < .001) and with wide inter-method confidence intervals (> ±106 minutes). Mean inter-method discrepancy did not differ on school nights at 15 y and 17 y but was greater at 17 y on non-school nights ( = .002). Inter-method discrepancy at 15 y was not correlated to that at 17 y. Mean change in self-reported school night bedtime from 15 y to 17 y did not differ from that by actigraphy, but self-reported bedtime changed less on non-school nights ( = .002). Two-year changes in self-reported bedtime did not correlate with changes measured by actigraphy.

Conclusions: Although methods were correlated, consistently earlier self-reported bedtime suggests report-bias. More varied non-school night bedtimes challenge the accuracy of self-report and actigraphy, reducing sensitivity to change. On school nights, the methods did not differ in group-level sensitivity to changes in bedtime. However, lack of correlation between bedtime changes by each method suggests sensitivity to individual-level change was different. Methodological differences in sensitivity to individual- and group-level change should be considered in longitudinal studies of adolescent sleep patterns.
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http://dx.doi.org/10.1123/jmpb.2019-0021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6889825PMC
December 2019

Extracellular vesicles from cod (Gadus morhua L.) mucus contain innate immune factors and deiminated protein cargo.

Dev Comp Immunol 2019 10 17;99:103397. Epub 2019 May 17.

Tissue Architecture and Regeneration Research Group, Department of Biomedical Sciences, University of Westminster, London, W1W 6UW, UK. Electronic address:

Extracellular vesicles are released from cells and participate in cell communication via transfer of protein and genetic cargo derived from the parent cells. EVs play roles in normal physiology and immunity and are also linked to various pathological processes. Peptidylarginine deiminases (PADs) are phylogenetically conserved enzymes with physiological and pathophysiological roles. PADs cause post-translational protein deimination, resulting in structural and, in some cases, functional changes in target proteins and are also linked to EV biogenesis. This study describes for the first time EVs isolated from cod mucosa. Mucosal EVs were characterised by electron microscopy, nanoparticle tracking analysis and EV-specific surface markers. Cod mucosal EVs were found to carry PAD, complement component C3 and C-reactive proteins. C3 was found to be deiminated in both whole mucus and mucosal EVs, with some differences, and further 6 deiminated immune and cytoskeletal proteins were identified in EVs by LC-MS/MS analysis. As mucosal surfaces of teleost fish reflect human mucosal surfaces, these findings may provide useful insights into roles of EVs in mucosal immunity throughout phylogeny.
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http://dx.doi.org/10.1016/j.dci.2019.103397DOI Listing
October 2019

Outbreak of viral haemorrhagic septicaemia (VHS) in lumpfish (Cyclopterus lumpus) in Iceland caused by VHS virus genotype IV.

J Fish Dis 2019 Jan 5;42(1):47-62. Epub 2018 Nov 5.

European Union Reference Laboratory for Fish Diseases, National Institute for Aquatic Resources, Technical University of Denmark, Copenhagen, Denmark.

A novel viral haemorrhagic septicaemia virus (VHSV) of genotype IV was isolated from wild lumpfish (Cyclopterus lumpus), brought to a land-based farm in Iceland, to serve as broodfish. Two groups of lumpfish juveniles, kept in tanks in the same facility, got infected. The virus isolated was identified as VHSV by ELISA and real-time RT-PCR. Phylogenetic analysis, based on the glycoprotein (G) gene sequences, may indicate a novel subgroup of VHSV genotype IV. In controlled laboratory exposure studies with this new isolate, there was 3% survival in the I.P. injection challenged group while there was 90% survival in the immersion group. VHSV was not re-isolated from fish challenged by immersion. In a cohabitation trial, lumpfish infected I.P. (shedders) were placed in tanks with naïve lumpfish as well as naïve Atlantic salmon (Salmo salar L.). 10% of the lumpfish shedders and 43%-50% of the cohabiting lumpfish survived after 4 weeks. 80%-92% of the Atlantic salmon survived, but no viral RNA was detected by real-time RT-PCR nor VHSV was isolated from Atlantic salmon. This is the first isolation of a notifiable virus in Iceland and the first report of VHSV of genotype IV in European waters.
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http://dx.doi.org/10.1111/jfd.12910DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7379627PMC
January 2019

Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny - Complement components C3 and C4 are post-translationally deiminated in halibut (Hippoglossus hippoglossus L.).

Dev Comp Immunol 2019 03 3;92:1-19. Epub 2018 Nov 3.

Tissue Architecture and Regeneration Research Group, School of Life Sciences, University of Westminster, London, W1W 6UW, UK. Electronic address:

Post-translational protein deimination is mediated by peptidylarginine deiminases (PADs), which are calcium dependent enzymes conserved throughout phylogeny with physiological and pathophysiological roles. Protein deimination occurs via the conversion of protein arginine into citrulline, leading to structural and functional changes in target proteins. In a continuous series of early halibut development from 37 to 1050° d, PAD, total deiminated proteins and deiminated histone H3 showed variation in temporal and spatial detection in various organs including yolksac, muscle, skin, liver, brain, eye, spinal cord, chondrocytes, heart, intestines, kidney and pancreas throughout early ontogeny. For the first time in any species, deimination of complement components C3 and C4 is shown in halibut serum, indicating a novel mechanism of complement regulation in immune responses and homeostasis. Proteomic analysis of deiminated target proteins in halibut serum further identified complement components C5, C7, C8 C9 and C1 inhibitor, as well as various other immunogenic, metabolic, cytoskeletal and nuclear proteins. Post-translational deimination may facilitate protein moonlighting, an evolutionary conserved phenomenon, allowing one polypeptide chain to carry out various functions to meet functional requirements for diverse roles in immune defences and tissue remodelling.
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http://dx.doi.org/10.1016/j.dci.2018.10.016DOI Listing
March 2019

Post-translational protein deimination in cod (Gadus morhua L.) ontogeny novel roles in tissue remodelling and mucosal immune defences?

Dev Comp Immunol 2018 10 14;87:157-170. Epub 2018 Jun 14.

Tissue Architecture and Regeneration Research Group, Department of Biomedical Sciences, University of Westminster, London, W1W 6UW, UK. Electronic address:

Peptidylarginine deiminases (PADs) are calcium dependent enzymes with physiological and pathophysiological roles conserved throughout phylogeny. PADs promote post-translational deimination of protein arginine to citrulline, altering the structure and function of target proteins. Deiminated proteins were detected in the early developmental stages of cod from 11 days post fertilisation to 70 days post hatching. Deiminated proteins were present in mucosal surfaces and in liver, pancreas, spleen, gut, muscle, brain and eye during early cod larval development. Deiminated protein targets identified in skin mucosa included nuclear histones; cytoskeletal proteins such as tubulin and beta-actin; metabolic and immune related proteins such as galectin, mannan-binding lectin, toll-like receptor, kininogen, Beta2-microglobulin, aldehyde dehydrogenase, bloodthirsty and preproapolipoprotein A-I. Deiminated histone H3, a marker for anti-pathogenic neutrophil extracellular traps, was particularly elevated in mucosal tissues in immunostimulated cod larvae. PAD-mediated protein deimination may facilitate protein moonlighting, allowing the same protein to exhibit a range of biological functions, in tissue remodelling and mucosal immune defences in teleost ontogeny.
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http://dx.doi.org/10.1016/j.dci.2018.06.006DOI Listing
October 2018

Pentraxins CRP-I and CRP-II are post-translationally deiminated and differ in tissue specificity in cod (Gadus morhua L.) ontogeny.

Dev Comp Immunol 2018 10 17;87:1-11. Epub 2018 May 17.

Tissue Architecture and Regeneration Research Group, Department of Biomedical Sciences, University of Westminster, London W1W 6UW, UK. Electronic address:

Pentraxins are fluid phase pattern recognition molecules that form an important part of the innate immune defence and are conserved between fish and human. In Atlantic cod (Gadus morhua L.), two pentraxin-like proteins have been described, CRP-I and CRP-II. Here we show for the first time that these two CRP forms are post-translationally deiminated (an irreversible conversion of arginine to citrulline) and differ with respect to tissue specific localisation in cod ontogeny from 3 to 84 days post hatching. While both forms are expressed in liver, albeit at temporally differing levels, CRP-I shows a strong association with nervous tissue while CRP-II is strongly associated to mucosal tissues of gut and skin. This indicates differing roles for the two pentraxin types in immune responses and tissue remodelling, also elucidating novel roles for CRP-I in the nervous system. The presence of deimination positive bands for cod CRPs varied somewhat between mucus and serum, possibly facilitating CRP protein moonlighting, allowing the same protein to exhibit a range of biological functions and thus meeting different functional requirements in different tissues. The presented findings may further current understanding of the diverse roles of pentraxins in teleost immune defences and tissue remodelling, as well as in various human pathologies, including autoimmune diseases, amyloidosis and cancer.
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http://dx.doi.org/10.1016/j.dci.2018.05.014DOI Listing
October 2018

[Bone mineral density and physical activity in 70-year-old Icelandic women.].

Laeknabladid 2003 Jul-Aug;89(7-8):585-93

Department of endochrinology, Landspitali University Hospital, Fossvogi, 108 Reykjavík, Iceland.

Objective: It is generally believed that exercise positively influences bone mineral density (BMD). Athletes have been found to have higher BMD than controls but it has proven difficult to reproduce these findings in the general population. RESULTS from cross-sectional studies on the relationship between exercise and BMD in postmenopausal women have been contradictory. In most studies the age range of subjects has been quite large. Few studies have concentrated on this relationship in elderly women, the largest risk group for osteoporosis and little is known if, and in that case what kind of, exercise has positive effects on BMD in these women. The purpose of this study was to examine the relation of BMD to exercise and current and lifetime occupational activity in 70-year-old Icelandic women.

Material And Methods: 248 women, all inhabitants in Reykjavik were investigated. BMD in the lumbar spine, femoral neck, total hip and total body was measured with dual energy X-ray absorptiometry (DXA) and the women filled out a questionnaire regarding general health issues, leisure time and occupational activity. Questions included number of leisure walks per week, frequency of other exercises and an attempt was made to estimate the intensity of the activities. Occupational activity was evaluated at ages 20-29 years, 30-44 years, 45-65 years as well as currently, and defined in four grades, from "mostly sedentary" to "hard work including walking".

Results: No relationship was found between number of walks and BMD. Significant positive correlation was found between number of other exercise sessions per week and total body BMD (b=0.008, p=0.01), but not total hip (p=0.09), femoral neck (p=0.15) or lumbar spine (p=0.07). Significant negative correlation was found between number of leisure walks and height loss from the age of 25 years (r=-0.211, p=0.001). No significant relationship was found between occupational activity and BMD.

Conclusion: RESULTS indicate that leisure time exercise can bring on some bone density benefits for elderly women. Leisure walking alone may not provide high enough stimuli to influence BMD but increasing number of other exercise sessions per week has positive relations to total body and possibly total hip and lumbar spine BMD. A randomized controlled study on the relationship between exercise and BMD in this age group should be conducted.
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October 2015

[The relationship between physical activity, body mass index, body composition and grip strength in an Icelandic population.].

Laeknabladid 2004 Jun;90(6):479-86

Iceland University Hospital, Fossvogi, 108 Reykjavík, Iceland.

Objective: To study physical activity among Icelandic adults and the relationship with anthropometric factors and grip strength.

Material And Methods: Randomly selected participants, 30-85 years of age, answered questions regarding exercise and diet. Body composition was measured with DXA, which detects the proportions of different body tissues. Height, weight and grip strength were measured and the body mass index (kg/m(2)) was calculated. The prevalence of regular physical activity was studied for men and women in the age groups of 30-45 years, 50-65 years and 70-85 years and the relationship to body mass index, body composition and grip strength examined. The possible preventive effect of exercise on overweight and obesity was also studied.

Results: Of 2310 invited, 1630 subjects (70.6%) participated. Mean participation in regular physical activity was 3-4 times a week but 19% of the women and 24% of the men did no exercise at all. In general, swimming, walking and calisthenics of various types and intensities were the most common forms of exercise and in the age group 30-45 year old 16% of the women and 8% of the men did strength training. 50.4% of women 30-45 years of age and 68.2% of 50-65 year old men were overweight or obese. Mean fat mass was highest in 70-85 year old women (38%) and men (27%). Occupational activity was not related to body mass index, body composition or grip strength. Significant negative relationship was found between frequency of exercise and fat mass. The relationship between grip strength and lean mass or exercise was non-significant. The odds ratio of being overweight or obesity was 0.5 (CI was 0.37-0.77 for women and 0.37-0.94 for men) for those who exercised five or more days per week compared to those who exercised less frequently.

Conclusion: One of four Icelandic men and one of five women do not participate in regular physical activity despite of strong scientific indications of various positive health effects of exercise. More than half of adult Icelanders are overweight or obese but the risk is halved among those who exercise at least five days per week, compared to those who exercise less frequently. Sedentary lifestyle is more common amongst Icelanders than in the neighboring countries and realistic goals need to be set to increase the participation in regular physical activity.
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June 2004