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- De Ruyck, Chris, et al.
(författare)
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n Appraisal of the use of Hydrogen-Isotope Methods to Delineate Origins of Migratory Saw-Whet Owls in North America
- 2013
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Ingår i: The Condor: ornithological applications. - : Oxford University Press (OUP). - 0010-5422 .- 1938-5129. ; 115:2, s. 366-374
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Tidskriftsartikel (refereegranskat)abstract
- Northern Saw-whet Owls (Aegolius acadicus) breed throughout the boreal forest of North America, but little is known about their population trends or distribution within this region. Analysis of stable hydrogen isotopes (delta H-2) in feathers can delineate origins of a variety of avian migrants, but raptors are reported to have high infra-feather isotopic variance and mean delta H-2 values higher than predicted from delta H-2 isoscapes specific to raptor feathers, making assignment of geographic origin sometimes difficult. We examined the applicability of delta H-2 analysis of saw-whet owl feathers to delineating origins of migrants and to assessing differences in the migratory behavior of adult and young owls by using multiple generations of feathers from owls captured during fall migration at the Delta Marsh Bird Observatory, Manitoba, 2006-2007. Values of delta H-2 in saw-whet owl feathers were higher than predicted from a delta H-2 isoscape specific to raptor feathers and from patterns of movements inferred from analysis of band recoveries. This effect was pronounced in adults, while values of delta H-2 in feathers of hatching-year owls fell primarily within the range predicted for the boreal forest northwest of Delta Marsh. Significant differences in delta H-2 values among feather generations suggest that physiological or behavioral differences between adults and young give rise to greater H-2 enrichment in adult feathers. These results indicate that current delta H-2 isoscapes for feathers cannot be used to track adult saw-whet owls reliably and further research into the mechanisms of H-2 enrichment in owl feathers is required.
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| 2. |
- Pfeiffer, Indriati, 1974, et al.
(författare)
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Vesicle Adsorption and Phospholipid Bilayer Formation on Topographically and Chemically Nanostructured Surfaces
- 2010
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 114:13, s. 4623-4631
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the influence of combined nanoscale topography and surface chemistry on lipid vesicle adsorption and supported bilayer formation on well-controlled model surfaces. To this end, we utilized colloidal lithography to nanofabricate pitted Au-SiO2 surfaces, where the top surface and the walls of the pits consisted of silicon dioxide whereas the bottom of the pits was made of gold. The diameter and height of the pits were fixed at 107 and 25 nm, respectively. Using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique and atomic force microscopy (AFM), we monitored the processes occurring upon exposure of these nanostructured surfaces to a solution of extruded unilamellar 1-palmitolyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) vesicles with a nominal diameter of 100 nm. To scrutinize the influence of surface chemistry, we studied two cases: (1) the bare gold surface at the bottom of the pits and (2) the gold passivated by biotinamidocaproyl-labeled bovine serum albumin (BBSA) prior to vesicle exposure. As in our previous work on pitted silicon dioxide surfaces, we found that the pit edges promote bilayer formation on the SiO2 surface for the vesicle size used here in both cases. Whereas in the first case we observed a slow, continuous adsorption of intact vesicles onto the gold surface at the bottom of the pits, the presence of BBSA in the second case prevented the adsorption of intact vesicles into the pits. Instead, our experimental results, together with free energy calculations for various potential membrane configurations, indicate the formation of a continuous, supported lipid bilayer that spans across the pits. These results are significantly important for various biotechnology applications utilizing patterned lipid bilayers and highlight the power of the combined QCM-D/AFM approach to study the mechanism of lipid bilayer formation on nanostructured surfaces.
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