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Träfflista för sökning "WFRF:(Nilsson Staffan) ;lar1:(lu)"

Sökning: WFRF:(Nilsson Staffan) > Lunds universitet

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1.
  • Nilsson, Christian, et al. (författare)
  • Cationic and anionic lipid-based nanoparticles in CEC for protein separation.
  • 2010
  • Ingår i: Electrophoresis. - : Wiley. - 0173-0835. ; 31:11, s. 1773-1779
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of new separation techniques is an important task in protein science. Herein, we describe how anionic and cationic lipid-based liquid crystalline nanoparticles can be used for protein separation. The potential of the suggested separation methods is demonstrated on green fluorescent protein (GFP) samples for future use on more complex samples. Three different CEC-LIF approaches for protein separation are described. (i) GFP and GFP N212Y, which are equally charged, were separated with high resolution by using anionic nanoparticles suspended in the electrolyte and adsorbed to the capillary wall. (ii) High efficiency (800 000 plates/m) and peak capacity were demonstrated separating GFP samples from Escherichia coli with cationic nanoparticles suspended in the electrolyte and adsorbed to the capillary wall. (iii) Three single amino-acid-substituted GFP variants were separated with high resolution using an approach based on a physical attached double-layer coating of cationic and anionic nanoparticles combined with anionic lipid nanoparticles suspended in the electrolyte. The soft and porous lipid-based nanoparticles were synthesized by a one-step procedure based on the self-assembly of lipids, and were biocompatible with a large surface-to-volume ratio. The methodology is still under development and the optimization of the nanoparticle chemistry and separation conditions can further improve the separation system. In contrast to conventional LC, a new interaction phase is introduced for every analysis, which minimizes carry-over and time-consuming column regeneration.
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2.
  • Nilsson, Christian, et al. (författare)
  • Hydrophobic Interaction Capillary Electrochromatography of Protein Mutants. Use of Lipid-Based Liquid Crystalline Nanoparticles as Pseudostationary Phase.
  • 2009
  • Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 81:1, s. 315-321
  • Tidskriftsartikel (refereegranskat)abstract
    • Nanoparticle-based hydrophobic interaction-capillary electrochromatography was utilized for separation of proteins with similar mass-to-charge ratio at neutral pH without organic modifier. Lipid-based liquid crystalline nanoparticles were prepared and used as pseudostationary phase, benefiting from their high biocompatibility, ease of preparation, and suspension stability at high concentrations. Use of laser-induced fluorescence enabled detection at high nanoparticle concentrations. Green fluorescent protein (GFP) and mutants of GFP harboring single or double amino acid substitutions with the same charge were separated in the described system but not in conventional capillary electrophoresis. Separation was achieved by increasing the salt concentration to promote hydrophobic interactions by shielding of the repulsive electrostatic interactions. In addition, the method was adapted to a capillary with an effective length of 6.7 cm, enabling fast separations and future applications on chip.
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3.
  • Nilsson, Christian, et al. (författare)
  • Nanoparticle-based capillary electroseparation of proteins in polymer capillaries under physiological conditions.
  • 2010
  • Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 31:3, s. 459-464
  • Tidskriftsartikel (refereegranskat)abstract
    • Totally porous lipid-based liquid crystalline nanoparticles were used as pseudostationary phase for capillary electroseparation with LIF detection of proteins at physiological conditions using unmodified cyclic olefin copolymer capillaries (Topas, 6.7 cm effective length). In the absence of nanoparticles, i.e. in CE mode, the protein samples adsorbed completely to the capillary walls and could not be recovered. In contrast, nanoparticle-based capillary electroseparation resolved green fluorescent protein from several of its impurities within 1 min. Furthermore, a mixture of native green fluorescent protein and two of its single-amino-acid-substituted variants was separated within 2.5 min with efficiencies of 400 000 plates/m. The nanoparticles prevent adsorption by introducing a large interacting surface and by obstructing the attachment of the protein to the capillary wall. A one-step procedure based on self-assembly of lipids was used to prepare the nanoparticles, which benefit from their biocompatibility and suspension stability at high concentrations. An aqueous tricine buffer at pH 7.5 containing lipid-based nanoparticles (2% w/w) was used as electrolyte, enabling separation at protein friendly conditions. The developed capillary-based method facilitates future electrochromatography of proteins on polymer-based microchips under physiological conditions and enables the initial optimization of separation conditions in parallel to the chip development.
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4.
  • Nilsson, Christian, et al. (författare)
  • Nanoparticle-based pseudostationary phases in CEC: A breakthrough in protein analysis?
  • 2011
  • Ingår i: Electrophoresis. - : Wiley. - 0173-0835. ; 32:10, s. 1141-1147
  • Forskningsöversikt (refereegranskat)abstract
    • This review focuses on major trends in nanoparticle-based pseudostationary phase (PSP) CEC since the publication of our previous reviews within nanoparticle-based CEC [Nilsson, C., et al., Electrophoresis 2006, 27, 76-83; Nilsson, C., et al., J. Chromatogr. A 2007, 1168, 212-224.]. Special attention is given to the development toward protein analysis, which is driven by the strong emergence of protein drug development in the pharmaceutical industry. Furthermore, we discuss the development in coupling different detection techniques with nanoparticle-based PSP CEC, which were originally predicted to be particularly cumbersome. However, at present, direct UV, LIF and ESI-MS have been used without any severe complications. Different types of nanoparticles used as PSP during the period include gold nanoparticles, carbon nanostructures and lipid-based nanoparticles. New materials (for example, different types of carbon nanostructures and self assembled lipid-based nanostructures) are a strong driving force for development in separation science. Finally, future trends in nanoparticles-based CEC are envisioned.
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5.
  • Nilsson, Christian, et al. (författare)
  • Use of nanoparticles in capillary and microchip electrochromatography
  • 2007
  • Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1168:1-2, s. 212-224
  • Forskningsöversikt (refereegranskat)abstract
    • Applications of nanoparticles are of rising interest in separation science, due to their favorable surface-to-volume ratio as well as their applicability in miniaturization. A stationary phase with large surface area in combination with an electroosmotic flow-driven system has great potential in a highly efficient separation system. This review covers the use of various nanoparticles as stationary or pseudostationary phase in capillary and microchip electrochromatography. The use of nanoparticles in pseudostationary phase capillary electrochromatography and open-tubular capillary electrochromatography are thoroughly discussed. The stationary and pseudostationary phases that are described include polymer nanoparticles, gold nanoparticles, silica nanoparticles, fullerenes and carbon nanotubes. (c) 2007 Elsevier B.V. All rights reserved.
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6.
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7.
  • Ellis, Vincenzo A., et al. (författare)
  • Explaining prevalence, diversity and host specificity in a community of avian haemosporidian parasites
  • 2020
  • Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 129:9, s. 1314-1329
  • Tidskriftsartikel (refereegranskat)abstract
    • Many hypotheses attempt to explain parasite–host associations, but rarely are they examined together in a single community. For hosts, key traits are the proportion of infected individuals (prevalence) and the diversity of parasites infecting them. A key parasite trait is host specificity, ranging from specialists infecting one or a few closely related species to generalists infecting many species. We tested 10 hypotheses to explain host-parasite associations; five ‘host-centric’ (e.g. prevalence is related to host abundance) and five ‘parasite-centric’ (e.g. parasite abundance is related to host specificity). We analyzed a community of 67 locally transmitted avian haemosporidian parasite lineages (genera Plasmodium, Haemoproteus or Leucocytozoon), sampled from 2726 birds (64 species) in southern Sweden. Among host-centric hypotheses, Haemoproteus and Leucocytozoon prevalence and Haemoproteus diversity were related to host habitat preferences, whereas there were no relationships with host abundance or body mass. Haemoproteus and Leucocytozoon prevalences were more similar among closely related than among distantly related host species. Haemoproteus prevalence and diversity were lower in host species with few close relatives (‘evolutionarily distinct’ hosts). Among parasite-centric hypotheses, most lineages, even relative generalists, infected closely related host species more often than expected by chance. However, the host species of Haemoproteus and Leucocytozoon lineages overlapped less among lineages than expected by chance. Specialists did not reach higher prevalences than generalists on single host species. However, the abundance of Haemoproteus lineages was related to host specificity with generalists more common than specialists; this was driven by three closely related generalists. Host specificity of parasites was unrelated to the abundance or evolutionarily distinctiveness of their hosts. Parasite communities are likely structured by many factors and cannot be explained by hypotheses focusing solely on hosts or parasites. However, we found consistent effects of host phylogenetic relationships, plausibly a result of evolutionarily conserved host immune systems limiting parasite distributions.
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8.
  • Moller, Anders Pape, et al. (författare)
  • Clutch-size variation in Western Palaearctic secondary hole-nesting passerine birds in relation to nest box design
  • 2014
  • Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 5:4, s. 353-362
  • Tidskriftsartikel (refereegranskat)abstract
    • Secondary hole-nesting birds that do not construct nest holes themselves and hence regularly breed in nest boxes constitute important model systems for field studies in many biological disciplines with hundreds of scientists and amateurs involved. Those research groups are spread over wide geographic areas that experience considerable variation in environmental conditions, and researchers provide nest boxes of varying designs that may inadvertently introduce spatial and temporal variation in reproductive parameters. We quantified the relationship between mean clutch size and nest box size and material after controlling for a range of environmental variables in four of the most widely used model species in the Western Palaearctic: great tit Parus major, blue tit Cyanistes caeruleus, pied flycatcher Ficedula hypoleuca and collared flycatcher F.albicollis from 365 populations and 79610 clutches. Nest floor area and nest box material varied non-randomly across latitudes and longitudes, showing that scientists did not adopt a random box design. Clutch size increased with nest floor area in great tits, but not in blue tits and flycatchers. Clutch size of blue tits was larger in wooden than in concrete nest boxes. These findings demonstrate that the size of nest boxes and material used to construct nest boxes can differentially affect clutch size in different species. The findings also suggest that the nest box design may affect not only focal species, but also indirectly other species through the effects of nest box design on productivity and therefore potentially population density and hence interspecific competition.
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9.
  • Moller, Anders Pape, et al. (författare)
  • Effects of interspecific coexistence on laying date and clutch size in two closely related species of hole-nesting birds
  • 2018
  • Ingår i: Journal of Animal Ecology. - : WILEY. - 0021-8790 .- 1365-2656. ; 87:6, s. 1738-1748
  • Tidskriftsartikel (refereegranskat)abstract
    • Coexistence between great tits Parus major and blue tits Cyanistes caeruleus, but also other hole-nesting taxa, constitutes a classic example of species co-occurrence resulting in potential interference and exploitation competition for food and for breeding and roosting sites. However, the spatial and temporal variations in coexistence and its consequences for competition remain poorly understood. We used an extensive database on reproduction in nest boxes by great and blue tits based on 87 study plots across Europe and Northern Africa during 1957-2012 for a total of 19,075 great tit and 16,729 blue tit clutches to assess correlative evidence for a relationship between laying date and clutch size, respectively, and density consistent with effects of intraspecific and interspecific competition. In an initial set of analyses, we statistically controlled for a suite of site-specific variables. We found evidence for an effect of intraspecific competition on blue tit laying date (later laying at higher density) and clutch size (smaller clutch size at higher density), but no evidence of significant effects of intraspecific competition in great tits, nor effects of interspecific competition for either species. To further control for site-specific variation caused by a range of potentially confounding variables, we compared means and variances in laying date and clutch size of great and blue tits among three categories of difference in density between the two species. We exploited the fact that means and variances are generally positively correlated. If interspecific competition occurs, we predicted a reduction in mean and an increase in variance in clutch size in great tit and blue tit when density of heterospecifics is higher than the density of conspecifics, and for intraspecific competition, this reduction would occur when density of conspecifics is higher than the density of heterospecifics. Such comparisons of temporal patterns of means and variances revealed evidence, for both species, consistent with intraspecific competition and to a smaller extent with interspecific competition. These findings suggest that competition associated with reproductive behaviour between blue and great tits is widespread, but also varies across large spatial and temporal scales.
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10.
  • Moller, Anders P., et al. (författare)
  • Variation in clutch size in relation to nest size in birds
  • 2014
  • Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:18, s. 3583-3595
  • Tidskriftsartikel (refereegranskat)abstract
    • Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of egg-laying. Parent birds should be selected to choose nest sites and to build optimally sized nests, yet our current understanding of clutch size-nest size relationships is limited to small-scale studies performed over short time periods. Here, we quantified the relationship between clutch size and nest size, using an exhaustive database of 116 slope estimates based on 17,472 nests of 21 species of hole and non-hole-nesting birds. There was a significant, positive relationship between clutch size and the base area of the nest box or the nest, and this relationship did not differ significantly between open nesting and hole-nesting species. The slope of the relationship showed significant intraspecific and interspecific heterogeneity among four species of secondary hole-nesting species, but also among all 116 slope estimates. The estimated relationship between clutch size and nest box base area in study sites with more than a single size of nest box was not significantly different from the relationship using studies with only a single size of nest box. The slope of the relationship between clutch size and nest base area in different species of birds was significantly negatively related to minimum base area, and less so to maximum base area in a given study. These findings are consistent with the hypothesis that bird species have a general reaction norm reflecting the relationship between nest size and clutch size. Further, they suggest that scientists may influence the clutch size decisions of hole-nesting birds through the provisioning of nest boxes of varying sizes.
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