To examine the prevalence of thyroid disease and dysfunction including thyroid autoimmunity in Norway.
All inhabitants 20 years and older (94009) in Nord-Trondelag were invited to participate in a ...health survey with a questionnaire and blood samples.
The prevalence of former diagnosed hyperthyroidism was 2.5% in females and 0.6% in males, hypothyroidism 4.8% and 0.9%, and goitre 2.9% and 0.4% respectively. In both sexes the prevalence increased with age. In individuals without a history of thyroid disease the median, 2.5 and 97.5 percentiles for TSH (mU/l) were 1.80 and 0.49-5.70 for females and 1. 50 and 0.56-4.60 for males. The TSH values increased with age. When excluding individuals with positive thyroid peroxidase antibodies (TPOAb) (>200U/ml), the 97.5 percentiles dropped to 3.60 mU/l and 3. 40 mU/l respectively. The prevalence of pathological TSH values in females and males were TSH >/=10mU/l 0.90% and 0.37%; TSH 4.1-9. 9mU/l 5.1% and 3.7%; and TSH</=0.05mU/l 0.45% and 0.20% respectively. The prevalence of positive TPOAb (>200U/ml) was 13.9% in females and 2.8% in males. In females the lowest percentage (7.9%) of positive TPOAb was seen with TSH 0.2-1.9mU/l and increased both with lower and higher levels of TSH. The percentage of males with positive TPOAb was lower than in females in all TSH groups except for those with TSH>10mU/l (85% TPOAb positive).
In spite of a high prevalence of recognised thyroid disease in the population a considerable number of inhabitants have undiagnosed thyroid dysfunction and also positive TPOAb.
The prevalence of thyroid dysfunction was investigated in a small, rural community located at the coast in Middle Norway. Two hundred persons (114 women and 86 men) of the total 802 persons over 70 ...years of age in the community were examined regarding thyroid dysfunction. Blood samples were drawn from 197 (113 women and 84 men). In women previously diagnosed hypothyroidism was found in 3.5% and previously diagnosed hyperthyroidism in 0.9%. In men no previously diagnosed thyroid disease was found. Undiagnosed primary hypothyroidism (TT4 less than 70 nmol/l and TSH greater than 6 mU/l) was found in 1.8% and 1.2% of women and men, respectively. Latent hypothyroidism (TT4 70-150 nmol/l and TSH greater than 6 mU/l) was found in 3.5% and 2.4%, and borderline hypothyroidism (TSH 4.5-6.0 mU/l) in 3.5% and 2.4%, respectively. Undiagnosed hyperthyroidism was not found in women but in 1.2% of men. Antibody to the thyroid microsomal antigen (TMA) greater than or equal to 400 was detected in 17.5% of women and 9.6% of men. Clearly elevated serum thyrotropin (TSH) concentrations or previously diagnosed thyroid disease were found in 21.7% and 37.5% of the TMA positive women and men, respectively.
The prevalence of thyroid dysfunction and thyroid antibodies was investigated in a small rural community (Naerøy) and in Oslo. Attendance rates in Naerøy and Oslo were 99 and 71%, respectively. The ...prevalence of undiagnosed latent hypothyroidism and primary hypothyroidism was 4.0 and 5.3% in women in Oslo and Naerøy respectively and 0 and 3.5% in men. Undiagnosed hyperthyroidism was detected in 1.2% of men in Naerøy and in 1% of women in Oslo. Antibody to the thyroid microsomal antigen in titre greater than or equal to 400 was detected in 10.2 and 17.5% of women and 7.3 and 7.2% of men in Oslo and Naerøy, respectively. Among women with antibody to the thyroid microsomal antigen in both Oslo and Naerøy, and among men in Naerøy, the prevalence of past or present thyroid dysfunction was increased.
Ecosystems across the globe are threatened by climate change and human activities. New rapid survey approaches for monitoring biodiversity would greatly advance assessment and understanding of these ...threats. Taking advantage of next‐generation DNA sequencing, we tested an approach we call metabarcoding: high‐throughput and simultaneous taxa identification based on a very short (usually <100 base pairs) but informative DNA fragment. Short DNA fragments allow the use of degraded DNA from environmental samples. All analyses included amplification using plant‐specific versatile primers, sequencing and estimation of taxonomic diversity. We tested in three steps whether degraded DNA from dead material in soil has the potential of efficiently assessing biodiversity in different biomes. First, soil DNA from eight boreal plant communities located in two different vegetation types (meadow and heath) was amplified. Plant diversity detected from boreal soil was highly consistent with plant taxonomic and growth form diversity estimated from conventional above‐ground surveys. Second, we assessed DNA persistence using samples from formerly cultivated soils in temperate environments. We found that the number of crop DNA sequences retrieved strongly varied with years since last cultivation, and crop sequences were absent from nearby, uncultivated plots. Third, we assessed the universal applicability of DNA metabarcoding using soil samples from tropical environments: a large proportion of species and families from the study site were efficiently recovered. The results open unprecedented opportunities for large‐scale DNA‐based biodiversity studies across a range of taxonomic groups using standardized metabarcoding approaches.
See also the Perspective by Chariton
Although ancient DNA from sediments (sedaDNA) has been used to investigate past ecosystems, the approach has never been directly compared with the traditional methods of pollen and macrofossil ...analysis. We conducted a comparative survey of 18 ancient permafrost samples spanning the Late Pleistocene (46–12.5 thousand years ago), from the Taymyr Peninsula in northern Siberia. The results show that pollen, macrofossils and sedaDNA are complementary rather than overlapping and, in combination, reveal more detailed information on plant palaeocommunities than can be achieved by each individual approach. SedaDNA and macrofossils share greater overlap in plant identifications than with pollen, suggesting that sedaDNA is local in origin. These two proxies also permit identification to lower taxonomic levels than pollen, enabling investigation into temporal changes in species composition and the determination of indicator species to describe environmental changes. Combining data from all three proxies reveals an area continually dominated by a mosaic vegetation of tundra‐steppe, pioneer and wet‐indicator plants. Such vegetational stability is unexpected, given the severe climate changes taking place in the Northern Hemisphere during this time, with changes in average annual temperatures of >22 °C. This may explain the abundance of ice‐age mammals such as horse and bison in Taymyr Peninsula during the Pleistocene and why it acted as a refugium for the last mainland woolly mammoth. Our finding reveals the benefits of combining sedaDNA, pollen and macrofossil for palaeovegetational reconstruction and adds to the increasing evidence suggesting large areas of the Northern Hemisphere remained ecologically stable during the Late Pleistocene.
The proposed age of the striking biogeographic disjunction between the Arctic and southernmost South America varies from more than 65 million to a few thousand years, but no estimates based on ...explicit models and molecular data are available. Here we address the origin of bipolarity in crowberries (Empetrum), which are heath-forming dwarf shrubs with animal-dispersed fruits. We apply a fossil-calibrated relaxed molecular clock to model sequence evolution in two nuclear low-copy and two plastid DNA regions from 41 individual plants (420 clones for the nuclear regions) representing the entire geographic distribution of crowberries. The plastid region matK and four fossil calibration points were used to infer the ages of the crowberry stem and crown groups. All analyses resolved three major crowberry clades (A-C). Clade A contained sequences from the eastern Canadian pink-fruited crowberry (E. eamesii) as sister to clades B and C, which both contained sequences from the black-fruited northern hemisphere crowberry (E. nigrum). Clade B also contained a subclade with all sequences from the red-fruited southern hemisphere crowberry, which is often referred to as a distinct species, E. rubrum. Its closest relatives were consistently identified as black-fruited plants from northwestern North America. The median time to the most recent common ancestor for northern and southern hemisphere crowberries was estimated to 0.56-0.93 Ma, and 0.26-0.59 Ma for the southern plants only. We conclude that a single dispersal by a bird from northwestern North America to southernmost South America, taking place in the Mid-Pleistocene, is sufficient to explain the disjunction in crowberries.
Palaeoenvironments and former climates are typically inferred from pollen and macrofossil records. This approach is time-consuming and suffers from low taxonomic resolution and biased taxon sampling. ...Here, we test an alternative DNA-based approach utilizing the P6 loop in the chloroplast trnL (UAA) intron; a short (13-158 bp) and variable region with highly conserved flanking sequences. For taxonomic reference, a whole trnL intron sequence database was constructed from recently collected material of 842 species, representing all widespread and/or ecologically important taxa of the species-poor arctic flora. The P6 loop alone allowed identification of all families, most genera (>75%) and one-third of the species, thus providing much higher taxonomic resolution than pollen records. The suitability of the P6 loop for analysis of samples containing degraded ancient DNA from a mixture of species is demonstrated by high-throughput parallel pyrosequencing of permafrost-preserved DNA and reconstruction of two plant communities from the last glacial period. Our approach opens new possibilities for DNA-based assessment of ancient as well as modern biodiversity of many groups of organisms using environmental samples.
The ability of species to track their ecological niche after climate change is a major source of uncertainty in predicting their future distribution. By analyzing DNA fingerprinting (amplified ...fragment-length polymorphism) of nine plant species, we show that long-distance colonization of a remote arctic archipelago, Svalbard, has occurred repeatedly and from several source regions. Propagules are likely carried by wind and drifting sea ice. The genetic effect of restricted colonization was strongly correlated with the temperature requirements of the species, indicating that establishment limits distribution more than dispersal. Thus, it may be appropriate to assume unlimited dispersal when predicting long-term range shifts in the Arctic.
Aim: Current evidence from temperate studies suggests that ectomycorrhizal (ECM) fungi require overland routes for migration because of their obligate symbiotic associations with woody plants. ...Despite their key roles in arctic ecosystems, the phylogenetic diversity and phylogeography of arctic ECM fungi remains little known. Here we assess the phylogenetic diversity of ECM communities in an isolated, formerly glaciated, high arctic archipelago, and provide explanations for their phylogeographic origins. Location: Svalbard. Methods: We generated and analysed internal transcribed spacer (ITS) nuclear ribosomal DNA sequences from both curated sporocarp collections (from Svalbard) and soil polymerase chain reaction (PCR) clone libraries (from Svalbard and the North American Arctic), compared these with publicly available sequences in GenBank, and estimated the phylogenetic diversity of ECM fungi in Svalbard. In addition, we conducted coalescent analyses to estimate migration rates in selected species. Results: Despite Svalbard's geographic isolation and arctic climate, its ECM fungi are surprisingly diverse, with at least 72 non-singleton operational taxonomic units (soil) and 109 phylogroups (soil + sporocarp). The most species-rich genera are Thelephora/Tomentella, Cortinarius and Inocybe, followed by Hebeloma, Russula, Lactarius, Entoloma, Sebacina, Clavulina, Laccaria, Leccinum and Alnicola. Despite the scarcity of available reference data from other arctic regions, the majority of the phylogroups (73.4%) were also found outside Svalbard. At the same time, all putative Svalbard 'endemics' were newly sequenced taxa from diverse genera with massive undocumented diversity. Overall, our results support long-distance dispersal more strongly than vicariance and glacial survival. However, because of the high variation in nucleotide substitution rates among fungi, allopatric persistence since the Pliocene, although unlikely, cannot be statistically rejected. Results from the coalescent analyses suggest recent gene flow among different arctic areas. Main conclusions: Our results indicate numerous recent colonization events and suggest that long-distance, transoceanic dispersal is widespread in arctic ECM fungi, which differs markedly from the currently prevailing view on the dispersal capabilities of ECM fungi. Our molecular evidence indicates that long-distance dispersal has probably played a major role in the phylogeographic history of some ECM fungi in the Northern Hemisphere. Our results may have implications for studies on the biodiversity, ecology and conservation of arctic fungi in general.
Glacial Survival of Boreal Trees in Northern Scandinavia Parducci, Laura; Jørgensen, Tina; Tollefsrud, Mari Mette ...
Science (American Association for the Advancement of Science),
03/2012, Volume:
335, Issue:
6072
Journal Article
Peer reviewed
It is commonly believed that trees were absent in Scandinavia during the last glaciation and first recolonized the Scandinavian Peninsula with the retreat of its ice sheet some 9000 years ago. Here, ...we show the presence of a rare mitochondrial DNA haplotype of spruce that appears unique to Scandinavia and with its highest frequency to the west—an area believed to sustain ice-free refugia during most of the last ice age. We further show the survival of DNA from this haplotype in lake sediments and pollen of Trondelag in central Norway dating back ~10,300 years and ch loro plast DNA of pine and spruce in lake sediments adjacent to the ice-free Andeya refugium in northwestern Norway as early as ~22,000 and 17,700 years ago, respectively. Our findings imply that conifer trees survived in ice-free refugia of Scandinavia during the last glaciation, challenging current views on survival and spread of trees as a response to climate changes.
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