| 1. |
- Westerlund, Fredrik, 1978, et al.
(author)
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Fluorescence enhancement from single DNA molecules confined in SiO 2 nanochannels
- 2010
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In: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2010, MicroTAS 2010; Groningen; Netherlands; 3 October 2010 through 7 October 2010. - 9781618390622
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Conference paper (peer-reviewed)abstract
- We demonstrate that the detected emission intensity from YOYO-labeled DNA molecules confined in 180 nm deep Si/SiO2 nanofunnels changes significantly and not monotonically with the width of the funnel, an emission enhancement that is only detected for emitted light polarized parallel to the channel. We explain the enhancement effect as being due to optical phenomena in the channels. The enhancement effect may be of importance for quantitative fluorescence microscopy and for experiments with a tight photon budget.
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| 2. |
- Mossberg, Ann-Kristin, et al.
(author)
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HAMLET Interacts with Lipid Membranes and Perturbs Their Structure and Integrity.
- 2010
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In: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 5:2
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Journal article (peer-reviewed)abstract
- BACKGROUND: Cell membrane interactions rely on lipid bilayer constituents and molecules inserted within the membrane, including specific receptors. HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a tumoricidal complex of partially unfolded alpha-lactalbumin (HLA) and oleic acid that is internalized by tumor cells, suggesting that interactions with the phospholipid bilayer and/or specific receptors may be essential for the tumoricidal effect. This study examined whether HAMLET interacts with artificial membranes and alters membrane structure. METHODOLOGY/PRINCIPAL FINDINGS: We show by surface plasmon resonance that HAMLET binds with high affinity to surface adherent, unilamellar vesicles of lipids with varying acyl chain composition and net charge. Fluorescence imaging revealed that HAMLET accumulates in membranes of vesicles and perturbs their structure, resulting in increased membrane fluidity. Furthermore, HAMLET disrupted membrane integrity at neutral pH and physiological conditions, as shown by fluorophore leakage experiments. These effects did not occur with either native HLA or a constitutively unfolded Cys-Ala HLA mutant (rHLA(all-Ala)). HAMLET also bound to plasma membrane vesicles formed from intact tumor cells, with accumulation in certain membrane areas, but the complex was not internalized by these vesicles or by the synthetic membrane vesicles. CONCLUSIONS/SIGNIFICANCE: The results illustrate the difference in membrane affinity between the fatty acid bound and fatty acid free forms of partially unfolded HLA and suggest that HAMLET engages membranes by a mechanism requiring both the protein and the fatty acid. Furthermore, HAMLET binding alters the morphology of the membrane and compromises its integrity, suggesting that membrane perturbation could be an initial step in inducing cell death.
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| 3. |
- Orlandi, Ivan, et al.
(author)
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Sir2-dependent asymmetric segregation of damaged proteins in ubp10 null mutants is independent of genomic silencing.
- 2010
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In: Biochimica et Biophysica Acta - Molecular Cell Research. - : Elsevier BV. - 0167-4889. ; 1803:5, s. 630-638
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Journal article (peer-reviewed)abstract
- Carbonylation of proteins is an irreversible oxidative damage that increases during both chronological and replicative yeast aging. In the latter, a spatial protein quality control system that relies on Sir2 is responsible for the asymmetrical damage segregation in the mother cells. Proper localization of Sir2 on chromatin depends on the deubiquitinating enzyme Ubp10, whose loss of function deeply affects the recombination and gene-silencing activities specific to Sir2. Here, we have analyzed the effects of SIR2 and UBP10 inactivations on carbonylated protein patterns obtained in two aging models such as stationary phase cells and size-selected old mother ones. In line with the endogenous situation of higher oxidative stress resulting from UBP10 inactivation, an increase of protein carbonylation has been found in the ubp10Δ stationary phase cells compared with sir2Δ ones. Moreover, Calorie Restriction had a salutary effect for both mutants by reducing carbonylated proteins accumulation. Remarkably, in the replicative aging model, whereas SIR2 inactivation resulted in a failure to establish damage asymmetry, the Sir2-dependent damage inheritance is maintained in the ubp10Δ mutant which copes with the increased oxidative damage by retaining it in the mother cells. This indicates that both Ubp10 and a correct association of Sir2 with the silenced chromatin are not necessary in such a process but also suggests that additional Sir2 activities on non-chromatin substrates are involved in the establishment of damage asymmetry.
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| 4. |
- Lindgren, Georg, et al.
(author)
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Non-traditional stochastic models for ocean waves
- 2010
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In: The European Physical Journal. Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 185, s. 209-224
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Research review (peer-reviewed)abstract
- We present two flexible stochastic models for 2D and 3D ocean waves with potential to reproduce severe and non-homogeneous sea conditions. The first family consists of generalized Lagrange models for the movements of individual water particles. These models can generate crest-trough and front-back statistically asymmetric waves, with the same degree of asymmetry as measured ocean waves. They are still in the Gaussian family and it is possible to calculate different slope distributions exactly from a wave energy spectrum. The second model is a random field model that is generated by a nested stochastic partial differential equation. This model can be adapted to spatially non-homogeneous sea conditions and it can approximate standard wave spectra. One advantage with this model is that Hilbert space approximations can be used to obtain computationally efficient representations with Markov-type properties that facilitate the use of sparse matrix techniques in simulation and estimation.
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| 5. |
- Westerlund, Fredrik, 1978, et al.
(author)
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Fluorescence Enhancement of Single DNA Molecules Confined in Si/SiO2 Nanochannels
- 2010
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In: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 10:16, s. 2049-2051
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Journal article (peer-reviewed)abstract
- We demonstrate that the detected emission intensity from YOYO- labeled DNA molecules confined in 180 nm deep Si/SiO2 nano- funnels changes significantly and not monotonically with the width of the funnel. This effect may be of importance for quantitative fluorescence microscopy and for experiments with a tight photon budget.
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