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- Aspenström, Pontus, et al.
(författare)
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Rho GTPases have diverse effects on the organization of the actin filament system
- 2004
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Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 377:Pt 2, s. 327-337
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Tidskriftsartikel (refereegranskat)abstract
- The Rho GTPases are related to the Ras proto-oncogenes and consist of 22 family members. These proteins have important roles in regulating the organization of the actin filament system, and thereby the morphogenesis of vertebrate cells as well as their ability to migrate. In an effort to compare the effects of all members of the Rho GTPase family, active Rho GTPases were transfected into porcine aortic endothelial cells and the effects on the actin filament system were monitored. Cdc42, TCL (TC10-like), Rac1-Rac3 and RhoG induced the formation of lamellipodia, whereas Cdc42, Rac1 and Rac2 also induced the formation of thick bundles of actin filaments. In contrast, transfection with TC10 or Chp resulted in the formation of focal adhesion-like structures, whereas Wrch-1 induced long and thin filopodia. Transfection with RhoA, RhoB or RhoC induced the assembly of stress fibres, whereas Rnd1-Rnd3 resulted in the loss of stress fibres, but this effect was associated with the formation of actin- and ezrin-containing dorsal microvilli. Cells expressing RhoD and Rif had extremely long and flexible filopodia. None of the RhoBTB or Miro GTPases had any major influence on the organization of the actin filament system; instead, RhoBTB1 and RhoBTB2 were present in vesicular structures, and Miro-1 and Miro-2 were present in mitochondria. Collectively, the data obtained in this study to some extent confirm earlier observations, but also allow the identification of previously undetected roles of the different members of the Rho GTPases.
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De första ljuva åren : lärares första tid i yrket
- 2001
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Samlingsverk (redaktörskap) (populärvet., debatt m.m.)abstract
- Kan den första tiden för nyblivna lärare utvecklas till att bli ett stöd i den professionella utvecklingen i stället för att vara en svår och omtumlande period? I denna antologi problematiseras lärarnas första tid som yrkesverksamma. Frågor som har att göra med deras utbildning, yrkessituation och professionella utveckling analyseras och diskuteras av nyblivna lärare, skolledare, fackliga organisationer och lärarutbildare. Nyutexaminerade pedagoger, verksamma i alltifrån förskolan till gymnasiet, beskriver sina erfarenheter från den första tiden i yrket. Till grund för diskussionen om att hitta former och innehåll som stödjer lärares professionella utveckling ligger en kritisk granskning av lärarutbildningarna, svensk och internationell forskning om den första tiden som lärare samt olika former och system för att stödja nya lärare. Boken vänder sig till lärare i slutskedet av sin grundläggande lärarutbildning, nyblivna lärare, mentorer, skolledare samt till lärarutbildare och forskare inom högskola och universitet.
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- Fransson, Åsa, et al.
(författare)
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Atypical Rho GTPases have roles in mitochondrial homeostasis and apoptosis
- 2003
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 278:8, s. 6495-6502
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Tidskriftsartikel (refereegranskat)abstract
- The human genomic sequencing effort has revealed the presence of a large number of Rho GTPases encoded by the human genome. Here we report the characterization of a new family of Rho GTPases with atypical features. These proteins, which were called Miro-1 and Miro-2 (for mitochondrial Rho), have tandem GTP-binding domains separated by a linker region containing putative calcium-binding EF hand motifs. Genes encoding Miro-like proteins were found in several eukaryotic organisms from Saccharomyces cerevisiae, Caenorhabditis elegans, and Drosophila melanogaster to mammals, indicating that these genes evolved early during evolution. Immunolocalization experiments, in which transfected NIH3T3 and COS 7 cells were stained for ectopically expressed Miro as well as for the endogenous Miro-1 protein, showed that Miro was present in mitochondria. Interestingly, overexpression of a constitutively active mutant of Miro-1 (Miro-1/Val-13) induced an aggregation of the mitochondrial network and resulted in an increased apoptotic rate of the cells expressing activated Miro-1. These data indicate a novel role for Rho-like GTPases in mitochondrial homeostasis and apoptosis.
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| 8. |
- Fransson, Åsa, 1971
(författare)
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Characterisation of Fractured Rock for Grouting Using Hydrogeological Methods
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sealing of tunnels by grouting demands knowledge concerning the fractured rock and the grout, followed by an appropriate choice of strategy and equipment. In this thesis, the characterisation of rock is the main issue and, since it addresses the engineering problem of producing a description for grouting, the properties of grout and the grouting procedure need to be considered. The conceptualisation is based on a grouting fan with a number of boreholes that cross fractures of different lengths and orientations and with varying ability to transmit water. These parameters are used to form a simplified model, in which discrete fractures and fractures along boreholes are considered central for further investigations. The ability to transmit water, or the transmissivity of the fractures, is a key parameter since it reflects the fracture aperture, an aperture that will influence both the penetration length and the volume of grout. Transmissivity, orientation and length of fractures are obtained by means of hydraulic tests and geological mapping. The question asked is whether these methods are useful and robust enough for grouting predictions. Investigations of geometry for a discrete fracture were performed using analytical and numerical approaches followed by laboratory and field experiments. For a larger scale and fractures along boreholes, a compilation of field data was made followed by the development of a non-parametric method, which gives a possible transmissivity distribution for fractures crossing a borehole. According to these investigations, the transmissivity or a closely related and more easily obtained parameter, referred to as the specific capacity, gives a good description of the fracture aperture. Furthermore, the median specific capacity of a small number of tests described the fracture in general, i.e. the effective or cross-fracture transmissivity. Probe holes have proved useful as a basis for choosing a grouting strategy and, here, the non-parametric method resulted in a low frequency of conductive fractures with log-normal distributed transmissivities. These parameters were used to analyse data from individual boreholes, which were subsequently connected to form a simplified model. The methodology was verified with a field experiment and should be useful in a grouting project.
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