| 1. |
- Werren, John H, et al.
(författare)
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Functional and evolutionary insights from the genomes of three parasitoid Nasonia species.
- 2010
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 327:5963, s. 343-8
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Tidskriftsartikel (refereegranskat)abstract
- We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.
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| 2. |
- Goossens, K. V. Y., et al.
(författare)
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Molecular Mechanism of Flocculation Self-Recognition in Yeast and Its Role in Mating and Survival
- 2015
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Ingår i: mBio. - 2150-7511 .- 2161-2129. ; 6:2, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- We studied the flocculation mechanism at the molecular level by determining the atomic structures of N-Flo1p and N-Lg-Flo1p in complex with their ligands. We show that they have similar ligand binding mechanisms but distinct carbohydrate specificities and affinities, which are determined by the compactness of the binding site. We characterized the glycans of Flo1p and their role in this binding process and demonstrate that glycan-glycan interactions significantly contribute to the cell-cell adhesion mechanism. Therefore, the extended flocculation mechanism is based on the self-interaction of Flo proteins and this interaction is established in two stages, involving both glycan-glycan and protein-glycan interactions. The crucial role of calcium in both types of interaction was demonstrated: Ca-2(+) takes part in the binding of the carbohydrate to the protein, and the glycans aggregate only in the presence of Ca-2(+). These results unify the generally accepted lectin hypothesis with the historically first-proposed "Ca-2(+)-bridge" hypothesis. Additionally, a new role of cell flocculation is demonstrated; i.e., flocculation is linked to cell conjugation and mating, and survival chances consequently increase significantly by spore formation and by introduction of genetic variability. The role of Flo1p in mating was demonstrated by showing that mating efficiency is increased when cells flocculate and by differential transcriptome analysis of flocculating versus nonflocculating cells in a low-shear environment (microgravity). The results show that a multicellular clump (floc) provides a uniquely organized multicellular ultrastructure that provides a suitable microenvironment to induce and perform cell conjugation and mating. IMPORTANCE Yeast cells can form multicellular clumps under adverse growth conditions that protect cells from harsh environmental stresses. The floc formation is based on the self-interaction of Flo proteins via an N-terminal PA14 lectin domain. We have focused on the flocculation mechanism and its role. We found that carbohydrate specificity and affinity are determined by the accessibility of the binding site of the Flo proteins where the external loops in the ligand-binding domains are involved in glycan recognition specificity. We demonstrated that, in addition to the Flo lectin-glycan interaction, glycan-glycan interactions also contribute significantly to cell-cell recognition and interaction. Additionally, we show that flocculation provides a uniquely organized multicellular ultrastructure that is suitable to induce and accomplish cell mating. Therefore, flocculation is an important mechanism to enhance long-term yeast survival.
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| 3. |
- van Eijsden, R. G. E., et al.
(författare)
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A universal fixation method based on quaternary ammonium salts (RNAlater) for omics-technologies: Saccharomyces cerevisiae as a case study
- 2013
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Ingår i: Biotechnology Letters. - : Springer Science and Business Media LLC. - 1573-6776 .- 0141-5492. ; 35:6, s. 891-900
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Tidskriftsartikel (refereegranskat)abstract
- Genomics, transcriptomics, proteomics and fluxomics are powerful omics-technologies that play a major role in today's research. For each of these techniques good sample quality is crucial. Major factors contributing to the quality of a sample is the actual sampling procedure itself and the way the sample is stored directly after sampling. It has already been described that RNAlater can be used to store tissues and cells in a way that the RNA quality and quantity are preserved. In this paper, we demonstrate that quaternary ammonium salts (RNAlater) are also suitable to preserve and store samples from Saccharomyces cerevisiae for later use with the four major omics-technologies. Moreover, it is shown that RNAlater also preserves the cell morphology and the potential to recover growth, permitting microscopic analysis and yeast cell culturing at a later stage.
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| 4. |
- Van Mulders, S. E., et al.
(författare)
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The Influence of Microgravity on Invasive Growth in Saccharomyces cerevisiae
- 2011
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Ingår i: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 11:1, s. 45-55
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the effects of microgravity on colony growth and the morphological transition from single cells to short invasive filaments in the model eukaryotic organism Saccharomyces cerevisiae. Two-dimensional spreading of the yeast colonies grown on semi-solid agar medium was reduced under microgravity in the Sigma 1278b laboratory strain but not in the CMBSESA1 industrial strain. This was supported by the Sigma 1278b proteome map under microgravity conditions, which revealed upregulation of proteins linked to anaerobic conditions. The Sigma 1278b strain showed a reduced invasive growth in the center of the yeast colony. Bud scar distribution was slightly affected, with a switch toward more random budding. Together, microgravity conditions disturb spatially programmed budding patterns and generate strain-dependent growth differences in yeast colonies on semi-solid medium.
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| 5. |
- Berna, P., Mrabet, N., T., Van Beeumen, J., Devreese, B., Porath, J., Vijayalakshmi, M., A.
(författare)
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Residue accessibility, hydrogen bonding, and molecular recognition: Metal-chelate probing of active site histidines in chymotrypsins
- 1997
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Ingår i: Biochemistry. ; 36:23, s. 6896-6905
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Brisbois, J., et al.
(författare)
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Flux penetration in a superconducting film partially capped with a conducting layer
- 2017
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 95:9
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Tidskriftsartikel (refereegranskat)abstract
- The influence of a conducting layer on the magnetic flux penetration in a superconducting Nb film is studied by magneto-optical imaging. The metallic layer partially covering the superconductor provides an additional velocity-dependent damping mechanism for the flux motion that helps to protect the superconducting state when thermomagnetic instabilities develop. If the flux advances with a velocity slower than omega = 2/mu(0)sigma t, where sigma is the cap layer conductivity and t is its thickness, the flux penetration remains unaffected, whereas for incoming flux moving faster than w, the metallic layer becomes an active screening shield. When the metallic layer is replaced by a perfect conductor, it is expected that the flux braking effect will occur for all flux velocities. We investigate this effect by studying Nb samples with a thickness step. Some of the observed features, namely the deflection of the flux trajectories at the border of the thick center, as well as the favored flux penetration at the indentation, are reproduced by time-dependent Ginzburg-Landau simulations.
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| 7. |
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| 8. |
- Naeye, B, et al.
(författare)
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Hemocompatibility of siRNA loaded dextran nanogels
- 2011
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 32:34, s. 9120-9127
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Tidskriftsartikel (refereegranskat)abstract
- Although the behavior of nanoscopic delivery systems in blood is an important parameter when contemplating their intravenous injection, this aspect is often poorly investigated when advancing from in vitro to in vivo experiments. In this paper, the behavior of siRNA loaded dextran nanogels in human plasma and blood is examined using fluorescence fluctuation spectroscopy, platelet aggregometry, flow cytometry and single particle tracking. Our results show that, in contrast to their negatively charged counterparts, positively charged siRNA loaded dextran nanogels cause platelet aggregation and show increased binding to human blood cells. Although PEGylating the nanogels did not have a significant effect on their interaction with blood cells, single particle tracking revealed that it is necessary to prevent their aggregation in human plasma. We therefore conclude that PEGylated negatively charged dextran nanogels are the most suited for further in vivo studies as they do not aggregate in human plasma and exhibit minimal interactions with blood cells.
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