| 1. |
- Cárdenas, Marité, et al.
(författare)
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SANS study of the interactions among DNA, a cationic surfactant, and polystyrene latex particles
- 2005
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 21:8, s. 3578-3583
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Tidskriftsartikel (refereegranskat)abstract
- The compaction of DNA by a cationic surfactant both in the bulk and adsorbed on the surface of latex particles was followed for the first time by SANS. In the bulk, a decrease in the overall size of the DNA coil in the presence of the cationic surfactant was observed at a negative-to-positive charge ratio far below the phase separation region, at a negative-to-positive charge ratio of 18. Additionally, large surfactant aggregates seem to form within the DNA-surfactant complex. On the other hand, DNA adsorbs onto the surface of latex particles, forming a thick layer, as evidenced by the fitting of the SANS data to a core-shell form factor. Addition of a cationic surfactant to the DNA-coated latex particles at a negative-to-positive charge ratio of 38 induces a slight decrease in the size of the particle layer, where the cationic surfactant is evenly distributed within the adsorbed layer. A further decrease of the negative-to-positive charge ratio to 18 induces a dramatic change in the SANS data that suggests significant compaction of the adsorbed layer and the formation of large surfactant aggregates, similar to those detected in the bulk.
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| 2. |
- Dreiss, A N, et al.
(författare)
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Local adaptation and matching habitat choice in female barn owls with respect to melanic coloration.
- 2012
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 25:1, s. 103-114
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Tidskriftsartikel (refereegranskat)abstract
- Local adaptation is a major mechanism underlying the maintenance of phenotypic variation in spatially heterogeneous environments. In the barn owl (Tyto alba), dark and pale reddish-pheomelanic individuals are adapted to conditions prevailing in northern and southern Europe, respectively. Using a long-term dataset from Central Europe, we report results consistent with the hypothesis that the different pheomelanic phenotypes are adapted to specific local conditions in females, but not in males. Compared to whitish females, reddish females bred in sites surrounded by more arable fields and less forests. Colour-dependent habitat choice was apparently beneficial. First, whitish females produced more fledglings when breeding in wooded areas, whereas reddish females when breeding in sites with more arable fields. Second, cross-fostering experiments showed that female nestlings grew wings more rapidly when both their foster and biological mothers were of similar colour. The latter result suggests that mothers should particularly produce daughters in environments that best match their own coloration. Accordingly, whiter females produced fewer daughters in territories with more arable fields. In conclusion, females displaying alternative melanic phenotypes bred in habitats providing them with the highest fitness benefits. Although small in magnitude, matching habitat selection and local adaptation may help maintain variation in pheomelanin coloration in the barn owl.
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