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- Alriksson, Björn, et al.
(författare)
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Overexpression of Saccharomyces cerevisiae transcription factor and multidrug resistance genes conveys enhanced resistance to lignocellulose-derived fermentation inhibitors
- 2010
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Ingår i: Process Biochemistry. - : Elsevier. - 1359-5113 .- 1873-3298. ; 45:2, s. 264-271
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Tidskriftsartikel (refereegranskat)abstract
- The presence of fermentation inhibitors in lignocellulose hydrolysates is an obstacle for achieving efficient fermentation of lignocellulose hydrolysates to ethanol and other commodities. In this investigation, the possibility of generating more inhibitor-resistant Saccharomyces cerevisiae by genetic engineering was explored. Based on previous results from studies of deletion mutants, three S. cerevisiae genes (ATR1, FLR1, YAP1) involved in multidrug resistance and stress response of yeast were selected for overexpression in three S. cerevisiae strains. The resistance of the transformed strains to lignocellulose-derived fermentation inhibitors and a dilute-acid spruce hydrolysate was evaluated in fermentation experiments. Overexpression of FLR1 resulted in enhanced resistance to the phenolic inhibitor coniferyl aldehyde and the furan aldehyde HMF (5-hydroxymethyl-2-furaldehyde). Overexpression of ATR1 conferred increased resistance to coniferyl aldehyde. Strains overexpressing YAP1, which encodes a transcription factor, displayed increased resistance to coniferyl aldehyde, HMF, and the spruce hydrolysate. An ethanol productivity of 0.17 g ethanol × l−1 × h−1 was achieved for a YAP1-overexpressing transformant cultivated in spruce hydrolysate, whereas a control transformant, which did not overexpress YAP1, only reached a productivity of 0.05 g ethanol × l−1 × h−1.
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2. |
- Chatterjee, Robin, et al.
(författare)
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Evaluation of the potential of fungal and plant laccases for active-packaging applications
- 2011
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Ingår i: Journal of Agricultural and Food Chemistry. - WASHINGTON : American Chemical Society. - 0021-8561 .- 1520-5118. ; 59:10, s. 5390-5395
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Tidskriftsartikel (refereegranskat)abstract
- Laccases from Trametes versicolor (TvL), Myceliophthora thermophila (MtL), and Rhus vernicifera (RvL) were investigated with regard to their potential utilization as oxygen scavengers in active packages containing food susceptible to oxidation reactions. The substrate selectivity of the laccases was investigated with a set of 17 reducing substrates, mainly phenolic compounds. The temperature dependence of reactions performed at low temperatures (4-31 °C) was studied. Furthermore, the laccases were subjected to immobilization in a latex/clay matrix and drying procedures performed at temperatures up to 105 °C. The results show that it is possible to immobilize the laccases with retained activity after dispersion coating, drying at 75-105 °C, and subsequent storage of the enzyme-containing films at 4 °C. TvL and, to some extent, MtL were promiscuous with regard to their reducing substrate, in the sense that the difference in activity with the 17 substrates tested was relatively small. RvL, on the other hand, showed high selectivity, primarily toward substrates resembling its natural substrate urushiol. When tested at 7 °C, all three laccases retained >20% of the activity they had at 25 °C, which suggests that it would be possible to utilize the laccases also in refrigerated food packages. Coating and drying resulted in a remaining enzymatic activity ranging from 18 to 53%, depending on the drying conditions used. The results indicate that laccases are useful for active-packaging applications and that the selectivity for reducing substrates is an important characteristic of laccases from different sources.
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- Eckstein, Rolf Lutz, et al.
(författare)
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Predicted changes in vegetation structure affect the susceptibility to invasion of bryophyte-dominated subarctic heath
- 2011
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 108:1, s. 177-183
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims A meta-analysis of global change experiments in arctic tundra sites suggests that plant productivity and the cover of shrubs, grasses and dead plant material (i.e. litter) will increase and the cover of bryophytes will decrease in response to higher air temperatures. However, little is known about which effects these changes in vegetation structure will have on seedling recruitment of species and invasibility of arctic ecosystems. Methods A field experiment was done in a bryophyte-dominated, species-rich subarctic heath by manipulating the cover of bryophytes and litter in a factorial design. Three phases of seedling recruitment (seedling emergence, summer seedling survival, first-year recruitment) of the grass Anthoxanthum alpinum and the shrub Betula nana were analysed after they were sown into the experimental plots. Key Results Bryophyte and litter removal significantly increased seedling emergence of both species but the effects of manipulations of vegetation structure varied strongly for the later phases of recruitment. Summer survival and first-year recruitment were significantly higher in Anthoxanthum. Although bryophyte removal generally increased summer survival and recruitment, seedlings of Betula showed high mortality in early August on plots where bryophytes had been removed. Conclusions Large species-specific variation and significant effects of experimental manipulations on seedling recruitment suggest that changes in vegetation structure as a consequence of global warming will affect the abundance of grasses and shrubs, the species composition and the susceptibility to invasion of subarctic heath vegetation.
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5. |
- Greve, Jens, et al.
(författare)
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Einleitung
- 2011. - 1
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Ingår i: Emergenz. - Berlin : Suhrkamp. - 9783518295175 ; , s. 7-36, s. 9-18
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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6. |
- Holmlund, Kristina, et al.
(författare)
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Group supervision for nursing students during their clinical placements : its content and meaning
- 2010
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Ingår i: Journal of Nursing Management. - : Hindawi Limited. - 0966-0429 .- 1365-2834. ; 18:6, s. 678-688
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Tidskriftsartikel (refereegranskat)abstract
- Aim To explore what situations students focus on during group supervision sessions, and what this supervision meant to nursing students during their clinical placements. Background Knowledge about clinical supervision of nursing students in groups is scarce concerning what situations the students bring to the sessions. Method Open-ended questionnaires were filled out by students after each session. Qualitative content analysis was performed. Results The content evolved as: being a nursing student, encountering demanding situations and becoming a nurse. The meaning of group supervision was captured in the categories: 'satisfaction of being together in the supervision group', 'new understanding and insights' and 'hesitation and discomfort'. A change of pattern was found over time showing a development among the students from a self-centred focus to a profession-centred focus. Conclusion The value of group supervision as a tool to support nursing students' personal and professional development was emphasized. The students' great need for and lack of support in 'bed-side nursing' was obvious. Implications for nursing management Our findings would be valuable for nurse managers when striving for a good learning environment in clinical placements, as well as for nursing teachers, in their supportive role to both students and preceptors.
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7. |
- Jafari, Rozbeh, 1977-, et al.
(författare)
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Localization of complexed anticytokeratin 8 scFv TS1-218 to HeLa HEp-2 multicellular tumor spheroids and experimental tumors
- 2010
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Ingår i: Cancer Biotherapy and Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1084-9785 .- 1557-8852. ; 25:4, s. 455-463
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Tidskriftsartikel (refereegranskat)abstract
- Recombinant single-chain fragment variable (scFv) antibodies with specificity to tumor antigens can be used to target tumors in vivo. The approach to use administration of complexes of idiotypic-anti-idiotypic scFvs when targeting tumors has not been tested earlier, and from a theoretical point it could contribute to longer in vivo circulation and improved targeting efficiency by dissociation, when in contact with the target antigen. In this study two models to evaluate the targeting efficiency of such complexes were used. HeLa HEp-2 tumor cells were grown as multicellular tumor spheroids (MCTS) and exposed to the antibody constructs in vitro. The behavior in vivo was tested in an in vivo tumor xenograft model. To increase the size of the anticytokeratin 8 scFv, TS1-218, complexes were formed between TS1-218 and its anti-idiotype, alphaTS1 scFv. The functionality of (125)I-labeled TS1-218 alone and in complex was studied in both models. The uptake patterns were similar in both models. The idiotypic TS1-218 was able to localize to the MCTS and xenografted tumors, both alone and in complex with alphaTS1 scFv. TS1-218 in complex, however, demonstrated a significantly higher uptake than the monomeric TS1-218 in both models (p < 0.0005 and p < 0.0089, respectively). When complexes were administered in vivo, a slower clearance and an increased tumor half-life could be observed. The present investigation indicates that administration of targeting antibodies, with initially blocked antigen-binding sites by complex formation with their anti-idiotypes, may improve targeting efficiency.
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8. |
- Johansson, Kristin, et al.
(författare)
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Oxygen scavenging enzymes in coatings : Effect of coating procedures on enzyme activity
- 2011
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Ingår i: Nordic Pulp & Paper Research Journal. - Stockholm : Mittuniversitetet. - 0283-2631 .- 2000-0669. ; 26:2, s. 197-204
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Tidskriftsartikel (refereegranskat)abstract
- The oxygen content in food packaging may be reduced by attaching oxygen scavengers to the packaging material. The critical parameters that determine the oxygen-scavenging ability of an enzyme-based coating i.e. pH, heat and coating color formulation were evaluated. Glucose oxidase, catalase and glucose were added to latex dispersions in the preparation of the coating colors. The enzymes were entrapped in the coating layers after coating and drying. The clay concentration and drying conditions were varied and the enzymatic activity of the coated layer was evaluated. The need for a pH-buffered system was also studied and the results indicated that, when using a carboxylated latex of a standard coating grade, a buffered system was not needed. A rapid drying at a high temperature was preferred over a slow drying at a low temperature in order to prevent pre-oxidation of the substrate in the wet coating color. The scavenging capacity of the coating was dependent on the amount of substrate for the enzyme reaction left after complete drying. The concentration of clay in the coating formulation was shown to have a marked impact on the oxygen-scavenging ability of the coated layer. The enzyme activity was increased by the addition of clay up to a pigment volume concentration (PVC) of ca. 10%. At higher concentrations of clay, the enzyme activity decreased until the critical pigment volume concentration (CPVC) was reached, probably due to the prevention of diffusion of oxygen and consumption of glucose in the coating process before the layer was completely dried. Further additions of clay above the CPVC resulted in an increased enzyme activity, probably due to the creation of a porous structure.
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10. |
- Karlsson, Svante, 1972-
(författare)
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Växande handel och ökad mobilitet
- 2011
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Ingår i: Geografiska Notiser. - Stockholm : Geografilärarnas Riksförening. - 0016-724X. ; 69:2, s. 70-78
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Tidskriftsartikel (refereegranskat)
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