1,232 research outputs found

    Studies in the genus Fritillaria L. (Liliaceae)

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    PhDGenus Fritillaria consists of approximately 140 species of bulbous herbaceous perennials with a bicontinental distribution (Eurasia, North America) across the temperate zone of the Northern Hemisphere. The genus includes species of horticultural commercial value and those used in Traditional Chinese Medicine (TCM) preparations. Since the mid-16th century species within genus Fritillaria have attracted much attention as ornamental plants in the Middle East and Europe. The genus has received much attention by geneticists in recent years because it includes species with an exceptionally large range of genome sizes, including a subgenus containing some of the largest diploid genome sizes so far recorded in plants. This thesis first presents the most comprehensive analysis of the phylogenetic relationships between the species to date, published in 2014 in Molecular Phylogenetics and Evolution. The work reveals two distinctive clades, one containing a small number of species from N. America and N. E. Asia and the other, with the majority of species, found in Europe, N. Africa, Middle East, China and Japan. This phylogenetic distribution of Fritillaria species indicates that two independent shifts towards giant genomes have taken place during evolution of the genus. One particularly charismatic species occurring across Eurasia is the Snake’s-head Fritillary (F. meleagris) with both horticultural and conservation importance. The thesis presents new genetic markers to analyse the relationships between populations of F. meleagris across Eurasia. Three distinct populations were found, in Northern Europe/Scandinavia, Eastern Europe and the Russian Federation. All the English populations are almost certainly derived from populations originally occurring in Northern Europe and likely introduced into England through multiple introductions. However, its origin in the British Isles remains a mystery, although recent research within this project has thrown new light on the history of its first record and description in France and its early presence in Britain

    Looking to thefuture

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    Panel discussion by speakers on their expectations, impressions and take-away message of the meeting

    Effects of elevational range shift on the morphology and physiology of a carabid beetle invading the sub-Antarctic Kerguelen Islands.

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    Climatic changes can induce geographic expansion and altitudinal shifts in the distribution of invasive species by offering more thermally suitable habitats. At the remote sub-Antarctic Kerguelen Islands, the predatory insect Merizodus soledadinus (Coleoptera: Carabidae), introduced in 1913, rapidly invaded coastal habitats. More recent colonisation of higher elevation habitats by this species could be underlain by their increased thermal suitability as the area has warmed. This study compared the effect of elevational range shift on the morphology and physiology of adult M. soledadinus sampled along two altitudinal transects (from the foreshore to 250 m a.s.l.) and a horizontal lowland transect orthogonal to the seashore (400 m length). Although high inter-individual and inter-transect variations in the traits examined were present, we observed that body mass of males and females tended to decrease with elevation, and that triglyceride contents decreased with distance from the shore. Moreover, protein contents of females as well as those of 26 metabolites were influenced significantly by distance to the foreshore. These results suggest that future climate change at the Kerguelen Islands will further assist the colonisation of lowland inland and higher altitude habitats by this aggressively invasive predator, by making previously sub-optimal habitats progressively more suitable

    Structure of the regulatory hyaluronan binding domain in the inflammatory leukocyte homing receptor CD44

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    Adhesive interactions involving CD44, the cell surface receptor for hyaluronan, underlie fundamental processes such as inflammatory leukocyte homing and tumor metastasis. Regulation of such events is critical and appears to be effected by changes in CD44 N-glycosylation that switch the receptor "on" or "off" under appropriate circumstances. How altered glycosylation influences binding of hyaluronan to the lectin-like Link module in CD44 is unclear, although evidence suggests additional flanking sequences peculiar to CD44 may be involved. Here we show using X-ray crystallography and NMR spectroscopy that these sequences form a lobular extension to the Link module, creating an enlarged HA binding domain and a formerly unidentified protein fold. Moreover, the disposition of key N-glycosylation sites reveals how specific sugar chains could alter both the affinity and avidity of CD44 HA binding. Our results provide the necessary structural framework for understanding the diverse functions of CD44 and developing novel therapeutic strategies

    Novel enantiopure bis(pyrrolo)tetrathiafulvalene donors exhibiting chiral crystal packing arrangements

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    Two novel enantiopure bis(pyrrolo[3,4-d])tetrathiafulvalene derivatives, substrates for preparing chiral conducting materials, show chiral crystal packing arrangements in which successive layers are rotated in accordance with an exact or approximate 43 axis. The corresponding donors containing fused dihydropyrrolegroups, and thus four more hydrogen atoms, form stacks along a crystal axis

    Titanium Nitride Films for Ultrasensitive Microresonator Detectors

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    Titanium nitride (TiNx) films are ideal for use in superconducting microresonator detectors because: a) the critical temperature varies with composition (0 < Tc < 5 K); b) the normal-state resistivity is large, \rho_n ~ 100 ÎĽ\muOhm cm, facilitating efficient photon absorption and providing a large kinetic inductance and detector responsivity; and c) TiN films are very hard and mechanically robust. Resonators using reactively sputtered TiN films show remarkably low loss (Q_i > 10^7) and have noise properties similar to resonators made using other materials, while the quasiparticle lifetimes are reasonably long, 10-200 ÎĽ\mus. TiN microresonators should therefore reach sensitivities well below 10^-19 WHz^(-1/2).Comment: to be published in AP

    A millimeter-wave kinetic inductance detector camera for long-range imaging through optical obscurants

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    Millimeter-wave imaging provides a promising option for long-range target detection through optical obscurants such as fog, which often occur in marine environments. Given this motivation, we are currently developing a 150 GHz polarization-sensitive imager using a relatively new type of superconducting pair-breaking detector, the kinetic inductance detector (KID). This imager will be paired with a 1.5 m telescope to obtain an angular resolution of 0.09° over a 3.5° field of view using 3,840 KIDs. We have fully characterized a prototype KID array, which shows excellent performance with noise strongly limited by the irreducible fluctuations from the ambient temperature background. Full-scale KID arrays are now being fabricated and characterized for a planned demonstration in a maritime environment later this year
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