| 21. |
- Bengtsson-Palme, Johan, 1985, et al.
(författare)
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Metaxa2 Database Builder: enabling taxonomic identification from metagenomic or metabarcoding data using any genetic marker
- 2018
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Ingår i: Bioinformatics (Oxford, England). - : Oxford University Press (OUP). - 1367-4811 .- 1367-4803. ; 34:23, s. 4027-4033
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Tidskriftsartikel (refereegranskat)abstract
- Correct taxonomic identification of DNA sequences is central to studies of biodiversity using both shotgun metagenomic and metabarcoding approaches. However, no genetic marker gives sufficient performance across all the biological kingdoms, hampering studies of taxonomic diversity in many groups of organisms. This has led to the adoption of a range of genetic markers for DNA metabarcoding. While many taxonomic classification software tools can be re-trained on these genetic markers, they are often designed with assumptions that impair their utility on genes other than the SSU and LSU rRNA. Here, we present an update to Metaxa2 that enables the use of any genetic marker for taxonomic classification of metagenome and amplicon sequence data.We evaluated the Metaxa2 Database Builder on eleven commonly used barcoding regions and found that while there are wide differences in performance between different genetic markers, our software performs satisfactorily provided that the input taxonomy and sequence data are of high quality.Freely available on the web as part of the Metaxa2 package at http://microbiology.se/software/metaxa2/.Supplementary data are available at Bioinformatics online.
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| 22. |
- Halwachs, Bettina, et al.
(författare)
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Critical Issues in mycobiota analysis
- 2017
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Fungi constitute an important part of the human microbiota and they play a significant role for health and disease development. Advancements made in the culture-independent analysis of microbial communities have broadened our understanding of the mycobiota, however, microbiota analysis tools have been mainly developed for bacteria (e.g., targeting the 16S rRNA gene) and they often fall short if applied to fungal marker-gene based investigations (i.e., internal transcribed spacers, ITS). In the current paper we discuss all major steps of a fungal amplicon analysis starting with DNA extraction from specimens up to bioinformatics analyses of next-generation sequencing data. Specific points are discussed at each step and special emphasis is placed on the bioinformatics challenges emerging during operational taxonomic unit (OTU) picking, a critical step in mycobiota analysis. By using an in silico ITS1 mock community we demonstrate that standard analysis pipelines fall short if used with default settings showing erroneous fungal community representations. We highlight that switching OTU picking to a closed reference approach greatly enhances performance. Finally, recommendations are given on how to perform ITS based mycobiota analysis with the currently available measures.
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| 23. |
- Elliott, David R., et al.
(författare)
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Bacterial and Fungal Communities in a Degraded Ombrotrophic Peatland Undergoing Natural and Managed Re-Vegetation
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- The UK hosts 15–19% of global upland ombrotrophic (rain fed) peatlands that are estimated to store 3.2 billion tonnes of carbon and represent a critical upland habitat with regard to biodiversity and ecosystem services provision. Net production is dependent on an imbalance between growth of peat-forming Sphagnum mosses and microbial decomposition by microorganisms that are limited by cold, acidic, and anaerobic conditions. In the Southern Pennines, land-use change, drainage, and over 200 years of anthropogenic N and heavy metal deposition have contributed to severe peatland degradation manifested as a loss of vegetation leaving bare peat susceptible to erosion and deep gullying. A restoration programme designed to regain peat hydrology, stability and functionality has involved re-vegetation through nurse grass, dwarf shrub and Sphagnum re-introduction. Our aim was to characterise bacterial and fungal communities, via high-throughput rRNA gene sequencing, in the surface acrotelm/mesotelm of degraded bare peat, long-term stable vegetated peat, and natural and managed restorations. Compared to long-term vegetated areas the bare peat microbiome had significantly higher levels of oligotrophic marker phyla (Acidobacteria, Verrucomicrobia, TM6) and lower Bacteroidetes and Actinobacteria, together with much higher ligninolytic Basidiomycota. Fewer distinct microbial sequences and significantly fewer cultivable microbes were detected in bare peat compared to other areas. Microbial community structure was linked to restoration activity and correlated with soil edaphic variables (e.g. moisture and heavy metals). Although rapid community changes were evident following restoration activity, restored bare peat did not approach a similar microbial community structure to non-eroded areas even after 25 years, which may be related to the stabilisation of historic deposited heavy metals pollution in long-term stable areas. These primary findings are discussed in relation to bare peat oligotrophy, re-vegetation recalcitrance, rhizosphere-microbe-soil interactions, C, N and P cycling, trajectory of restoration, and ecosystem service implications for peatland restoration.
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| 24. |
- Zhao, M., et al.
(författare)
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Phylogenetic position of the Wallcreeper Tichodroma muraria
- 2016
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Ingår i: Journal of Ornithology = Journal fur Ornithologie. - : Springer Science and Business Media LLC. - 0021-8375 .- 1439-0361. ; 157:3, s. 913-918
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Tidskriftsartikel (refereegranskat)abstract
- The Wallcreeper Tichodroma muraria is usually placed in a monotypic family or subfamily within the superfamily Certhioidea, with assumed close relationships to Certhia (treecreepers), Sitta (nuthatches) and Salpornis (spotted creepers). Previous studies have suggested that Tichodroma is most closely related to Sitta, alternatively to Salpornis. We analysed the relationships of Tichodroma using two mitochondrial and five nuclear loci. The tree based on concatenated sequences strongly supported a sister relationship between Tichodroma and Sitta, as well as between Salpornis and Certhia. However, species tree analysis (MP-EST) was unable to resolve these relationships, and although the concatenation tree remains the best hypothesis, more data are needed to corroborate this. © 2016, Dt. Ornithologen-Gesellschaft e.V.
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| 25. |
- Anslan, Sten, et al.
(författare)
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Great differences in performance and outcome of high-throughput sequencing data analysis platforms for fungal metabarcoding
- 2018
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Ingår i: MycoKeys. - : Pensoft Publishers. - 1314-4057 .- 1314-4049. ; 39, s. 29-40
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Tidskriftsartikel (refereegranskat)abstract
- Along with recent developments in high-throughput sequencing (HTS) technologies and thus fast accumulation of HTS data, there has been a growing need and interest for developing tools for HTS data processing and communication. In particular, a number of bioinformatics tools have been designed for analysing metabarcoding data, each with specific features, assumptions and outputs. To evaluate the potential effect of the application of different bioinformatics workflow on the results, we compared the performance of different analysis platforms on two contrasting high-throughput sequencing data sets. Our analysis revealed that the computation time, quality of error filtering and hence output of specific bioinformatics process largely depends on the platform used. Our results show that none of the bioinformatics workflows appears to perfectly filter out the accumulated errors and generate Operational Taxonomic Units, although PipeCraft, LotuS and PIPITS perform better than QIIME2 and Galaxy for the tested fungal amplicon dataset. We conclude that the output of each platform requires manual validation of the OTUs by examining the taxonomy assignment values.
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| 26. |
- Abrego, Nerea, et al.
(författare)
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Airborne DNA reveals predictable spatial and seasonal dynamics of fungi
- 2024
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 631, s. 835-842
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Tidskriftsartikel (refereegranskat)abstract
- Fungi are among the most diverse and ecologically important kingdoms in life. However, the distributional ranges of fungi remain largely unknown as do the ecological mechanisms that shape their distributions1,2. To provide an integrated view of the spatial and seasonal dynamics of fungi, we implemented a globally distributed standardized aerial sampling of fungal spores3. The vast majority of operational taxonomic units were detected within only one climatic zone, and the spatiotemporal patterns of species richness and community composition were mostly explained by annual mean air temperature. Tropical regions hosted the highest fungal diversity except for lichenized, ericoid mycorrhizal and ectomycorrhizal fungi, which reached their peak diversity in temperate regions. The sensitivity in climatic responses was associated with phylogenetic relatedness, suggesting that large-scale distributions of some fungal groups are partially constrained by their ancestral niche. There was a strong phylogenetic signal in seasonal sensitivity, suggesting that some groups of fungi have retained their ancestral trait of sporulating for only a short period. Overall, our results show that the hyperdiverse kingdom of fungi follows globally highly predictable spatial and temporal dynamics, with seasonality in both species richness and community composition increasing with latitude. Our study reports patterns resembling those described for other major groups of organisms, thus making a major contribution to the long-standing debate on whether organisms with a microbial lifestyle follow the global biodiversity paradigms known for macroorganisms4,5.
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| 27. |
- Green, Leon, et al.
(författare)
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Ancestral Sperm Ecotypes Reveal Multiple Invasions of a Non-Native Fish in Northern Europe
- 2021
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Ingår i: Cells. - : MDPI AG. - 2073-4409. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- For externally fertilising organisms in the aquatic environment, the abiotic fertilisation medium can be a strong selecting force. Among bony fishes, sperm are adapted to function in a narrow salinity range. A notable exception is the family Gobiidae, where several species reproduce across a wide salinity range. The family also contains several wide-spread invasive species. To better understand how these fishes tolerate such varying conditions, we measured sperm performance in relation to salinity from a freshwater and a brackish population within their ancestral Ponto-Caspian region of the round goby, Neogobius melanostomus. These two ancestral populations were then compared to nine additional invaded sites across northern Europe, both in terms of their sperm traits and by using genomic SNP markers. Our results show clear patterns of ancestral adaptations to freshwater and brackish salinities in their sperm performance. Population genomic analyses show that the ancestral ecotypes have generally established themselves in environments that fit their sperm adaptations. Sites close to ports with intense shipping show that both outbreeding and admixture can affect the sperm performance of a population in a given salinity. Rapid adaptation to local conditions is also supported at some sites. Historical and contemporary evolution in the traits of the round goby sperm cells is tightly linked to the population and seascape genomics as well as biogeographic processes in these invasive fishes. Since the risk of a population establishing in an area is related to the genotype by environment match, port connectivity and the ancestry of the round goby population can likely be useful for predicting the species spread.
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| 28. |
- Nilsson, R. Henrik, 1976, et al.
(författare)
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How, not if, is the question mycologists should be asking about DNA-based typification
- 2023
-
Ingår i: MycoKeys. - : Pensoft Publishers. - 1314-4057 .- 1314-4049. ; :96, s. 143-157
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Tidskriftsartikel (refereegranskat)abstract
- Fungal metabarcoding of substrates such as soil, wood, and water is uncovering an unprecedented number of fungal species that do not seem to produce tangible morphological structures and that defy our best attempts at cultivation, thus falling outside the scope of the International Code of Nomenclature for algae, fungi, and plants. The present study uses the new, ninth release of the species hypotheses of the UNITE database to show that species discovery through environmental sequencing vastly outpaces traditional, Sanger sequencing-based efforts in a strongly increasing trend over the last five years. Our findings chal-lenge the present stance of some in the mycological community - that the current situation is satisfactory and that no change is needed to "the code" - and suggest that we should be discussing not whether to allow DNA-based descriptions (typifications) of species and by extension higher ranks of fungi, but what the precise requirements for such DNA-based typifications should be. We submit a tentative list of such criteria for further discussion. The present authors hope for a revitalized and deepened discussion on DNA-based typification, because to us it seems harmful and counter-productive to intentionally deny the overwhelming majority of extant fungi a formal standing under the International Code of Nomenclature for algae, fungi, and plants.
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| 29. |
- Hartmann, Martin, et al.
(författare)
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Significant and persistent impact of timber harvesting on soil microbial communities in Northern coniferous forests
- 2012
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Ingår i: The ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 6:12, s. 2199-2218
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Tidskriftsartikel (refereegranskat)abstract
- Forest ecosystems have integral roles in climate stability, biodiversity and economic development. Soil stewardship is essential for sustainable forest management. Organic matter (OM) removal and soil compaction are key disturbances associated with forest harvesting, but their impacts on forest ecosystems are not well understood. Because microbiological processes regulate soil ecology and biogeochemistry, microbial community structure might serve as indicator of forest ecosystem status, revealing changes in nutrient and energy flow patterns before they have irreversible effects on long-term soil productivity. We applied massively parallel pyrosequencing of over 4.6 million ribosomal marker sequences to assess the impact of OM removal and soil compaction on bacterial and fungal communities in a field experiment replicated at six forest sites in British Columbia, Canada. More than a decade after harvesting, diversity and structure of soil bacterial and fungal communities remained significantly altered by harvesting disturbances, with individual taxonomic groups responding differentially to varied levels of the disturbances. Plant symbionts, like ectomycorrhizal fungi, and saprobic taxa, such as ascomycetes and actinomycetes, were among the most sensitive to harvesting disturbances. Given their significant ecological roles in forest development, the fate of these taxa might be critical for sustainability of forest ecosystems. Although abundant bacterial populations were ubiquitous, abundant fungal populations often revealed a patchy distribution, consistent with their higher sensitivity to the examined soil disturbances. These results establish a comprehensive inventory of bacterial and fungal community composition in northern coniferous forests and demonstrate the long-term response of their structure to key disturbances associated with forest harvesting.
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| 30. |
- Airaud, M, et al.
(författare)
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Biologie - Les manuels visuels pour la Licence
- 2018
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- En couleurs et très illustré, ce manuel a été conçu pour vous qui débutez un cursus scientifique universitaire. Il vous permettra d’acquérir les connaissances fondamentales en biologie, mais aussi la démarche et la rigueur scientifiques indispensables aux études supérieures. De multiples rubriques vous garantissent un apprentissage progressif et complet : un cours visuel avec de nombreux exemples concrets pour introduire et illustrer les notions et concepts clés ; des encadrés méthodologiques pour vous guider vers les bonnes pratiques et vous faire découvrir les grandes méthodes expérimentales ; des focus sur des applications, sujets de recherche ou thèmes d’actualité ; des repères historiques ; de nombreux QCM et exercices (tous corrigés) pour tester vos acquis et vous entraîner.
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