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- Tosh, J., et al.
(författare)
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Evolutionary history of the Afro-Madagascan Ixora species (Rubiaceae) : species diversification and distribution of key morphological traits inferred from dated molecular phylogenetic trees
- 2013
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 112:9, s. 1723-1742
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Tidskriftsartikel (refereegranskat)abstract
- Previous work on the pantropical genus Ixora has revealed an Afro-Madagascan clade, but as yet no study has focused in detail on the evolutionary history and morphological trends in this group. Here the evolutionary history of Afro-Madagascan Ixora spp. (a clade of approx. 80 taxa) is investigated and the phylogenetic trees compared with several key morphological traits in taxa occurring in Madagascar. Phylogenetic relationships of Afro-Madagascan Ixora are assessed using sequence data from four plastid regions (petD, rps16, rpoB-trnC and trnL-trnF) and nuclear ribosomal external transcribed spacer (ETS) and internal transcribed spacer (ITS) regions. The phylogenetic distribution of key morphological characters is assessed. Bayesian inference (implemented in BEAST) is used to estimate the temporal origin of Ixora based on fossil evidence. Two separate lineages of Madagascan taxa are recovered, one of which is nested in a group of East African taxa. Divergence in Ixora is estimated to have commenced during the mid Miocene, with extensive cladogenesis occurring in the Afro-Madagascan clade during the Pliocene onwards. Both lineages of Madagascan Ixora exhibit morphological innovations that are rare throughout the rest of the genus, including a trend towards pauciflorous inflorescences and a trend towards extreme corolla tube length, suggesting that the same ecological and selective pressures are acting upon taxa from both Madagascan lineages. Novel ecological opportunities resulting from climate-induced habitat fragmentation and corolla tube length diversification are likely to have facilitated species radiation on Madagascar.
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- Barres, L., et al.
(författare)
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RECONSTRUCTING THE EVOLUTION AND BIOGEOGRAPHIC HISTORY OF TRIBE CARDUEAE (COMPOSITAE)
- 2013
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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 100:5, s. 867-882
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Tidskriftsartikel (refereegranskat)abstract
- • Premise of the study: Tribe Cardueae (thistles) forms one of the largest tribes in the family Compositae (2400 species), with representatives in almost every continent. The greatest species richness of Cardueae occurs in the Mediterranean region where it forms an important element of its flora. New fossil evidence and a nearly resolved phylogeny of Cardueae are used here to reconstruct the spatiotemporal evolution of this group. • Methods: We performed maximum parsimony and Bayesian phylogenetic inference based on nuclear ribosomal DNA and chloroplast DNA markers. Divergence times and ancestral area reconstructions for main lineages were estimated using penalized likelihood and dispersal–vicariance analyses, respectively, and integrated over the posterior distribution of the phylogeny from the Bayesian Markov chain Monte Carlo analysis to accommodate uncertainty in phylogenetic relationships. • Key results: The phylogeny shows that subtribe Cardopatiinae is sister to the remaining subtribes, and subtribes Carlininae and Echinopsinae appear as consecutive sister-clades to the Carduinae/Centaureinae. Tribe Cardueae is inferred to have originated around the Mid Eocene in West Asia, which is also the ancestral area of most subtribes within Cardueae. Diversification within each subtribe began during the Oligocene-Miocene period. • Conclusions: Most diversification events within Cardueae are related to the continuous cycles of area connection and division between the Anatolian microplate and the western Mediterranean Basin during the Oligocene-Miocene and with the uplift of the Himalayan range from the Miocene onward. From these two regions, thistles dispersed and colonized the rest of the continents (e.g., the New World, Africa, and Australia), most likely during the colder Pliocene-Pleistocene period.
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- Claudel, C., et al.
(författare)
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Large-scale phylogenetic analysis of Amorphophallus (Araceae) derived from nuclear and plastid sequences reveals new subgeneric delineation
- 2017
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Ingår i: Botanical Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 184:1, s. 32-45
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Tidskriftsartikel (refereegranskat)abstract
- Remarkably little is known about the evolution of the emblematic genus Amorphophallus. To shed new light on phylogenetic relationships between species of Amorphophallus and test its current classification, the first well-sampled molecular phylogenetic analysis is presented here, comprising 157 species for which we generate nuclear (ITS1) and plastid (rbcL and matK) sequences. Our combined plastid and nuclear maximum likelihood and Bayesian inferences provide a solid backbone for subgeneric delineation in supporting the existence of four major clades. These latter clades are here formally recognized as subgenera (two of which are new): Amorphophallus, Metandrium, Scutandrium and Afrophallus. Each subgenus is discussed based on selected morphological features and additional traits (e.g. distribution). Finally, our results strongly support the inclusion of the genus Pseudodracontium in Amorphophallus and the required taxonomic changes are proposed here. In addition to clarifying species relationships in Amorphophallus and proposing a new infrageneric classification, this study provides a baseline for researchers working on the evolution and biogeography of Araceae and more broadly on the tropical flora, especially in Southeast Asia.
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- Kunzmann, Andrea, et al.
(författare)
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Efficient internalization of silica-coated iron oxide nanoparticles of different sizes by primary human macrophages and dendritic cells
- 2011
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Ingår i: Toxicology and Applied Pharmacology. - : Elsevier BV. - 0041-008X .- 1096-0333. ; 253:2, s. 81-93
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Tidskriftsartikel (refereegranskat)abstract
- Engineered nanoparticles are being considered for a wide range of biomedical applications, from magnetic resonance imaging to "smart" drug delivery systems. The development of novel nanomaterials for biomedical applications must be accompanied by careful scrutiny of their biocompatibility. In this regard, particular attention should be paid to the possible interactions between nanoparticles and cells of the immune system, our primary defense system against foreign invasion. On the other hand, labeling of immune cells serves as an ideal tool for visualization, diagnosis or treatment of inflammatory processes, which requires the efficient internalization of the nanoparticles into the cells of interest. Here, we compare novel monodispersed silica-coated iron oxide nanoparticles with commercially available dextran-coated iron oxide nanoparticles. The silica-coated iron oxide nanoparticles displayed excellent magnetic properties. Furthermore, they were nontoxic to primary human monocyte-derived macrophages at all doses tested whereas dose-dependent toxicity of the smaller silica-coated nanoparticles (30 nm and 50 nm) was observed for primary monocyte-derived dendritic cells, but not for the similarly small dextran-coated iron oxide nanoparticles. No macrophage or dendritic cell secretion of pro-inflammatory cytokines was observed upon administration of nanoparticles. The silica-coated iron oxide nanoparticles were taken up to a significantly higher degree when compared to the dextran-coated nanoparticles, irrespective of size. Cellular internalization of the silica-coated nanoparticles was through an active, actin cytoskeleton-dependent process. We conclude that these novel silica-coated iron oxide nanoparticles are promising materials for medical imaging, cell tracking and other biomedical applications. (C) 2011 Elsevier Inc. All rights reserved.
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