| 1. |
|
|
| 2. |
- Blomqvist, Per, 1972-
(författare)
-
Samtal om skrivbedömning : Lärares normer, beslut och samstämmighet
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis reports and discusses results from a qualitative study of Swedish teachers' writing assessment in upper secondary school. Based on teacher group discussions, the study investigates teachers' interactions, expressions of norms and decisions when assessing and grading students' writing in the subject of Swedish.The aim of the study is to describe and analyze how teachers interact and what they pay attention to when discussing writing assessment. In relation to this aim the following three research questions were posed: (1) What characterizes the teachers' conversations about writing assessment? (2) What assessment norms do the teachers express? (3) What decisions do they make?The theoretical perspectives are dialogical and pedagogical. From a dialogical point of view, the assessment conversations are considered as social acts where teachers in interaction collectively create meaning. Furthermore, the assessment conversations are considered as pedagogical, as a part of teachers' reflective work to discuss how to assess students' work and how to make decisions about further instructions and grading. The methods used to describe and analyze interactional patterns, expressions of norms and decisions in these assessment conversations are topic analysis and initiative-response-analysis.The empirical data consists of audio and video recordings from three teacher groups' conversations about writing assessment, comprising a total of 17 Swedish teachers from three upper secondary schools. Data was also collected via a questionnaire with the individual teacher's grading of the students' writing and evaluation of the assessment conversations.The results show that teachers' assessments of students' writing focus on much more, and partly other, criteria than their pedagogical decisions. The quality standards that teachers express in the discussions about student texts focus mostly on communicative quality, language style and text structure but also on content and the use of sources. The pedagogical decisions, on the other hand, almost exclusively focus on text structure and the use of sources.The results also show that shortcomings in the students' texts are crucial for teachers' summative assessments. Meanwhile, the teachers also express that students' age, their writing development in the course and the national test must be considered. These assessment norms can be compensatory and have a substantial impact on these teachers' decisions on summative assessments. The teacher groups show considerable variation in the basis for their decisions regarding summative assessment of students' writing.Finally, the teachers demonstrate a high degree of consistency within each teacher group when discussing summative assessment of students' writing. However, the assessments that individual teachers make after the discussions comply only to some extent with the group's decisions. The least degree of consistency was shown by the teacher group who, in the discussion, seemed the most consistent. Decision-making processes in these discussions are characterized by low intensity, where few assessment alternatives are being considered. The overall assessment consistency between the teacher groups was found to be low.
|
|
| 3. |
- Chumnarnsilpa, Sakesit, 1967-, et al.
(författare)
-
Calcium ion exchange in crystalline gelsolin
- 2006
-
Ingår i: Journal of Molecular Biology. - England : Academic Press. - 0022-2836 .- 1089-8638. ; 357:3, s. 773-782
-
Tidskriftsartikel (refereegranskat)abstract
- Gelsolin is a calcium and pH-sensitive modulator of actin filament length. Here, we use X-ray crystallography to examine the extraction and exchange of calcium ions from their binding sites in different crystalline forms of the activated N and C-terminal halves of gelsolin, G1-G3 and G4-G6, respectively. We demonstrate that the combination of calcium and low pH activating conditions do not induce conformational changes in G4-G6 beyond those elicited by calcium alone. EGTA is able to remove calcium ions bound to the type I and type II metal ion-binding sites in G4-G6. Constrained by crystal contacts and stabilized by interdomain interaction surfaces, the gross structure of calcium-depleted G4-G6 remains that of the activated form. However, high-resolution details of changes in the ion-binding sites may represent the initial steps toward restoration of the arrangement of domains found in the calcium-free inactive form of gelsolin in solution. Furthermore, bathing crystals with the trivalent calcium ion mimic, Tb3+, results in anomalous scattering data that permit unequivocal localization of terbium ions in each of the proposed type I and type II ion-binding sites of both halves of gelsolin. In contrast to predictions based on solution studies, we find that no calcium ion is immune to exchange.
|
|
| 4. |
- Grenklo, Staffan, et al.
(författare)
-
A crucial role for profilin-actin in the intracellular motility of Listeria monocytogenes
- 2003
-
Ingår i: EMBO reports. - London : Nature Publishing Group. - 1469-221X .- 1469-3178. ; 4:5, s. 523-529
-
Tidskriftsartikel (refereegranskat)abstract
- We have examined the effect of covalently crosslinked profilin–actin (PxA), which closely matches the biochemical properties of ordinary profilin–actin and interferes with actin polymerization in vitro and in vivo, on Listeria monocytogenes motility. PxA caused a marked reduction in bacterial motility, which was accompanied by the detachment of bacterial tails. The effect of PxA was dependent on its binding to proline-rich sequences, as shown by the inability of PH133SxA, which cannot interact with such sequences, to impair Listeria motility. PxA did not alter the motility of a Listeria mutant that is unable to recruit Ena (Enabled)/VASP (vasodilator-stimulated phosphoprotein) proteins and profilin to its surface. Finally, PxA did not block the initiation of actin-tail formation, indicating that profilin–actin is only required for the elongation of actin filaments at the bacterial surface. Our findings provide further evidence that profilin–actin is important for actin-based processes, and show that it has a key function in Listeria motility.
|
|
| 5. |
- Grenklo, Staffan, et al.
(författare)
-
Tropomyosin assembly intermediates in the control of MF-system turnover
- 2008
-
Ingår i: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335 .- 1618-1298. ; 87:11, s. 905-920
-
Tidskriftsartikel (refereegranskat)abstract
- Tropomyosin is a coiled-coil α-helical protein, which self-associates in a head-to-tail fashion along polymers of actin to produce thin filaments. Mammalian non-muscle cells express a large number of tropomyosin isoforms, which are differentially regulated during embryogenesis and associated with specialized actin microfilament ensembles in cells. The function of tropomyosin in specifying form and localization of these subcellular structures, and the precise mechanism(s) by which they carry out their functions, is unclear. This paper reports that, while the major fraction of non-muscle cell tropomyosin resides in actin thin filaments of the cytomatrix, the soluble part of the cytoplasm contains tropomyosins in the form of actin-free multimers, which are isoform specific and of high molecular weight (MWapp 180,000–250,000). Stimulation of motile cells with growth factors induces a rapid, actin polymerization-dependent outgrowth of lamellipodia and filopodia. Concomitantly, the levels of tropomyosin isoform-specific multimers decrease, suggesting their involvement in actin thin filament formation. Malignant tumor cells have drastically altered levels and composition of tropomyosin isoform-specific multimers as well as tropomyosin in the cytomatrix.
|
|
| 6. |
- Hillberg, Louise, 1977-
(författare)
-
Elements in regulation of the microfilament system
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with cell motility. The process of rapid actin polymerization in the lamellipodium of a migrating cell is responsible for its protrusion. Studies have been made on some of the elements behind this event and special interest has been focused on the protein tropomyosin. Muscle tropomyosin and its function in regulating muscle contraction, have been studied for decades, but there are also multiple tropomyosin isoforms in non-muscle cells, whose detailed function has not been revealed. Previous work at this department has shown an involvement of tropomyosin in the assembly of actin in vitro in the presence of gelsolin, and initial studies located tropomyosin to the lamellipodium of stimulated human fibroblasts. However, the general view is that tropomyosin is depleted from the advancing cell edge, observations noted in support of the current model of Arp2/3 dependent formation of actin filaments in lamellipodia. We have demonstrated the presence of tropomyosins in lamellae of migrating cells using different antibodies against non-muscle tropomyosin in indirect immunofluorescence. Also, the distribution of tagged non-muscle tropomyosin isoforms was analyzed in transfected cells. We conclude that tropomyosin is present in lamellipodia, all the way to their advancing edges. The presence of tropomyosin in the leading edge urges for tropomyosin to be taken into account when modelling cell motility. Furthermore, the nature of cytosolic tropomyosin was investigated by gel filtration chromatography and the conclusion was that in fibroblasts, approximately 10% of the tropomyosin is present in the cytosol, while the remaining 90% is associated with actin microfilaments in the cytomatrix. Interestingly, the soluble tropomyosin was found to exist mostly in a multimeric form of high molecular weight. Surprisingly, skeletal muscle tropomyosin and recombinant TM1 expressed in Escherichia coli forms multimers, a phenomenon not observed previously.
|
|
| 7. |
- Hillberg, Louise, et al.
(författare)
-
Tropomyosins are present in lamellipodia of motile cells
- 2006
-
Ingår i: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335 .- 1618-1298. ; 85:5, s. 399-409
-
Tidskriftsartikel (refereegranskat)abstract
- This paper shows that high-molecular-weight tropomyosins (TMs), as well as shorter isoforms of this protein, are present in significant amounts in lamellipodia and filopodia of spreading normal and transformed cells. The presence of TM in these locales was ascertained by staining of cells with antibodies reacting with endogenous TMs and through the expression of hemaglutinin- and green fluorescent protein-tagged TM isoforms. The observations are contrary to recent reports suggesting the absence of TMs in regions,where polymerization of actin takes place, and indicate that the view of the role of TM in the formation of actin filaments needs to be significantly revised.
|
|
| 8. |
- Käck, Annika, 1965-
(författare)
-
Digital Competence and Ways of Thinking and Practising in Swedish Teacher Education : Experiences by teachers with a foreign teaching degree
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish government recognises foreign academic education and the professional qualifications of its immigrants by allocating resources to programmes that bridge the gap between immigrants’ education and the specific requirements for work in Sweden. The context of inquiry for this thesis is teachers with a foreign teaching degree, who come from 57 countries or regions and are studying at four Swedish universities. They attend a bridging programme called “Further Education for Foreign Teachers” (in Swedish, Utländska Lärares Vidareutbildning). The purpose of this thesis is to study the unfamiliar ways of thinking and practising teachers with a foreign teaching degree encounter in Swedish teacher education, emphasising digital competence. Five different theoretical frameworks and models are used in this thesis: ways of thinking and practising, redefined transformative learning, the framework of Technological Pedagogical Content Knowledge (TPACK), the European Digital Competence Frameworks for Citizens (DigComp 2.1), and the Digital Competence of Educators framework (DigCompEdu). A convergent mixed methods research design was applied; the combined datasets consisted of: (a) a web survey to which 228 teachers responded; (b) five focus groups each consisting of 25 teachers; (c) nine individual interviews; (d) 30 reflective texts written by 15 teachers. Findings show that the participants are not a homogenous group and cannot be treated as such. The common ground is that they are foreign-born teachers who have all immigrated to Sweden. The diversity covers a range, from being quite familiar to being unfamiliar with the Swedish educational context. This thesis reveals the diversity of their digital competence, as they score from foundational proficiency levels to highly specialised ones in TPACK as well as in the European framework DigComp 2.1. Furthermore, their expressed digital competence is found within all role descriptors in the European framework for the digital competence of educators DigCompEdu, from newcomer to pioneer. Diversity was found in teaching philosophy, the role of a teacher, view of the students, how learning occurs, and finally, comprehension of the relationship between education and society. Moreover, the findings highlight that some ways of thinking and practising were unfamiliar to the participants, such as teaching and learning methods, new learning environments, examination practices, further, the communication between teachers and students. Unfamiliarity was also found regarding the extent to which society demands digital competence in the curricula. The participants expressed that their roles as teachers in a new country were unfamiliar and took time to get used to. Therefore, placement supervisors were found to be of great importance for the development of teachers’ digital competence, as they function as mediators and model what it is to be a teacher in Sweden. The analysis shows that all teachers, not only teachers with a migrant background, need digital competence at an advanced level to develop digital competence among students. Thus, educators must identify unfamiliar ways of thinking and practising, plan for authentic competence development, and address the diversity in digital competence. This thesis contributes to empirical findings, developing tools and models to assist teacher educators to change monocultural teaching to an inclusive practice in which diversity is integrated.
|
|
| 9. |
- Lassing, Ingrid, et al.
(författare)
-
Tropomyosin is a tetramer under physiological salt conditions.
- 2010
-
Ingår i: Cytoskeleton (Hoboken, N.J.). - : Wiley. - 1949-3592 .- 1949-3584. ; 67:9, s. 599-607
-
Tidskriftsartikel (refereegranskat)abstract
- Tropomyosin (TM) is a coiled-coil dimer of alpha-helical peptides, which self associates in a head- to-tail fashion along actin polymers, conferring stability to the microfilaments and serving a regulatory function in acto-myosin driven force generation. While the major amount of TM is associated with filaments also in non-muscle cells, it was recently reported that there are isoform-specific pools of TM multimers (not associated with F-actin), which appear to be utilized during actin polymerization and reformed during depolymerization. To determine the size of these multimers, skeletal muscle TM was studied under different salt conditions using gel-filtration and sucrose gradient sedimentation, and compared with purified non-muscle TM 1 and 5, as well as with TM present in non-muscle cell extracts and skeletal muscle TM added to such extracts. Under physiological salt conditions TM appears as a single homogenous peak with the Stokes radius 8.2 nm and the molecular weight (mw) 130,000. The corresponding values for TM 5 are 7.7 nm and 104,000, respectively. This equals four peptides, implying that native TM is a tetramer in physiological salt. It is therefore concluded that the TM multimers are tetramers.
|
|
| 10. |
- Lindberg, Uno, et al.
(författare)
-
Isolation and Characterization of Adenovirus Messenger Ribonucleic Acid in Productive Infection
- 1972
-
Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 10:5, s. 909-919
-
Tidskriftsartikel (refereegranskat)abstract
- Messenger ribonucleic acid (mRNA) from cells productively infected with adenovirus type 2 was isolated by affinity chromatography on polyuridylic acid [poly (U)] bound to Sepharose. At least 90% of the polyadenylic acid [poly (A)]-containing polysomal mRNA was retained by the poly (U) Sepharose and thus separated from more than 95% of the ribosomal RNA and transfer RNA. In these experiments, 65% of the early (3 to 5 hr postinfection) and 85% of the late (14 to 16 hr postinfection) virus-specific RNA was retained by the poly (U) Sepharose. Early in the infection 18%, and late in the infection more than 95%, of the poly (A)-containing fraction, eluted from the poly (U) Sepharose with 90% formamide, was adenovirus-specific, as shown by exhaustive hybridization. Different patterns, containing several distinct species of viral mRNA, were detected early and late in the infectious cycle. No distinct viral mRNA lacking poly (A) was discovered.
|
|
