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- Willerslev, E, et al.
(författare)
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Fifty thousand years of arctic vegetation change and megafauna diet
- 2014
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 506:7486, s. 47-47
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Tidskriftsartikel (refereegranskat)abstract
- Although it is generally agreed that the Arctic flora is among the youngest and least diverse on Earth, the processes that shaped it are poorly understood. Here we present 50 thousand years (kyr) of Arctic vegetation history, derived from the first large-scale ancient DNA metabarcoding study of circumpolar plant diversity. For this interval we also explore nematode diversity as a proxy for modelling vegetation cover and soil quality, and diets of herbivorous megafaunal mammals, many of which became extinct around 10 kyr bp (before present). For much of the period investigated, Arctic vegetation consisted of dry steppe-tundra dominated by forbs (non-graminoid herbaceous vascular plants). During the Last Glacial Maximum (25–15 kyr bp), diversity declined markedly, although forbs remained dominant. Much changed after 10 kyr bp, with the appearance of moist tundra dominated by woody plants and graminoids. Our analyses indicate that both graminoids and forbs would have featured in megafaunal diets. As such, our findings question the predominance of a Late Quaternary graminoid-dominated Arctic mammoth steppe.
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- Mourier, A, et al.
(författare)
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Mitofusin 2 is required to maintain mitochondrial coenzyme Q levels
- 2015
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Ingår i: The Journal of cell biology. - : Rockefeller University Press. - 1540-8140 .- 0021-9525. ; 208:4, s. 429-442
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondria form a dynamic network within the cell as a result of balanced fusion and fission. Despite the established role of mitofusins (MFN1 and MFN2) in mitochondrial fusion, only MFN2 has been associated with metabolic and neurodegenerative diseases, which suggests that MFN2 is needed to maintain mitochondrial energy metabolism. The molecular basis for the mitochondrial dysfunction encountered in the absence of MFN2 is not understood. Here we show that loss of MFN2 leads to impaired mitochondrial respiration and reduced ATP production, and that this defective oxidative phosphorylation process unexpectedly originates from a depletion of the mitochondrial coenzyme Q pool. Our study unravels an unexpected and novel role for MFN2 in maintenance of the terpenoid biosynthesis pathway, which is necessary for mitochondrial coenzyme Q biosynthesis. The reduced respiratory chain function in cells lacking MFN2 can be partially rescued by coenzyme Q10 supplementation, which suggests a possible therapeutic strategy for patients with diseases caused by mutations in the Mfn2 gene.
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- Zhang, Guojie, et al.
(författare)
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Comparative genomics reveals insights into avian genome evolution and adaptation
- 2014
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 346:6215, s. 1311-1320
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Tidskriftsartikel (refereegranskat)abstract
- Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits.
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