| 1. |
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| 2. |
- von Beek, Christopher, et al.
(författare)
-
A two-step activation mechanism enables mast cells to differentiate their response between extracellular and invasive enterobacterial infection
- 2024
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- Mast cells localize to mucosal tissues and contribute to innate immune defense against infection. How mast cells sense, differentiate between, and respond to bacterial pathogens remains a topic of ongoing debate. Using the prototype enteropathogen Salmonella Typhimurium (S.Tm) and other related enterobacteria, here we show that mast cells can regulate their cytokine secretion response to distinguish between extracellular and invasive bacterial infection. Tissue-invasive S.Tm and mast cells colocalize in the mouse gut during acute Salmonella infection. Toll-like Receptor 4 (TLR4) sensing of extracellular S.Tm, or pure lipopolysaccharide, causes a modest induction of cytokine transcripts and proteins, including IL-6, IL-13, and TNF. By contrast, type-III-secretion-system-1 (TTSS-1)-dependent S.Tm invasion of both mouse and human mast cells triggers rapid and potent inflammatory gene expression and >100-fold elevated cytokine secretion. The S.Tm TTSS-1 effectors SopB, SopE, and SopE2 here elicit a second activation signal, including Akt phosphorylation downstream of effector translocation, which combines with TLR activation to drive the full-blown mast cell response. Supernatants from S.Tm-infected mast cells boost macrophage survival and maturation from bone-marrow progenitors. Taken together, this study shows that mast cells can differentiate between extracellular and host-cell invasive enterobacteria via a two-step activation mechanism and tune their inflammatory output accordingly.
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| 3. |
- von Beek, Christopher, et al.
(författare)
-
A two-step activation mechanism enables mast cells to differentiate their response between extracellular and invasive enterobacterial infection
- 2024
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- Mast cells localize to mucosal tissues and contribute to innate immune defense against infection. How mast cells sense, differentiate between, and respond to bacterial pathogens remains a topic of ongoing debate. Using the prototype enteropathogen Salmonella Typhimurium (S.Tm) and other related enterobacteria, here we show that mast cells can regulate their cytokine secretion response to distinguish between extracellular and invasive bacterial infection. Tissue-invasive S.Tm and mast cells colocalize in the mouse gut during acute Salmonella infection. Toll-like Receptor 4 (TLR4) sensing of extracellular S.Tm, or pure lipopolysaccharide, causes a modest induction of cytokine transcripts and proteins, including IL-6, IL-13, and TNF. By contrast, type-III-secretion-system-1 (TTSS-1)-dependent S.Tm invasion of both mouse and human mast cells triggers rapid and potent inflammatory gene expression and >100-fold elevated cytokine secretion. The S.Tm TTSS-1 effectors SopB, SopE, and SopE2 here elicit a second activation signal, including Akt phosphorylation downstream of effector translocation, which combines with TLR activation to drive the full-blown mast cell response. Supernatants from S.Tm-infected mast cells boost macrophage survival and maturation from bone-marrow progenitors. Taken together, this study shows that mast cells can differentiate between extracellular and host-cell invasive enterobacteria via a two-step activation mechanism and tune their inflammatory output accordingly.
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| 4. |
- Akopyan, Karen, et al.
(författare)
-
Translocation of surface-localized effectors in type III secretion
- 2011
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:4, s. 1639-1644
-
Tidskriftsartikel (refereegranskat)abstract
- Pathogenic Yersinia species suppress the host immune response by using a plasmid-encoded type III secretion system (T3SS) to translocate virulence proteins into the cytosol of the target cells. T3SS-dependent protein translocation is believed to occur in one step from the bacterial cytosol to the target-cell cytoplasm through a conduit created by the T3SS upon target cell contact. Here, we report that T3SS substrates on the surface of Yersinia pseudotuberculosis are translocated into target cells. Upon host cell contact, purified YopH coated on Y. pseudotuberculosis was specifically and rapidly translocated across the target-cell membrane, which led to a physiological response in the infected cell. In addition, translocation of externally added YopH required a functional T3SS and a specific translocation domain in the effector protein. Efficient, T3SS-dependent translocation of purified YopH added in vitro was also observed when using coated Salmonella typhimurium strains, which implies that T3SS-mediated translocation of extracellular effector proteins is conserved among T3SS-dependent pathogens. Our results demonstrate that polarized T3SS-dependent translocation of proteins can be achieved through an intermediate extracellular step that can be reconstituted in vitro. These results indicate that translocation can occur by a different mechanism from the assumed single-step conduit model.
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| 5. |
- Antti, Henrik, et al.
(författare)
-
Metabolic profiling for detection of staphylococcus aureus infection and antibiotic resistance
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:2
-
Tidskriftsartikel (refereegranskat)abstract
- Due to slow diagnostics, physicians must optimize antibiotic therapies based on clinical evaluation of patients without specific information on causative bacteria. We have investigated metabolomic analysis of blood for the detection of acute bacterial infection and early differentiation between ineffective and effective antibiotic treatment. A vital and timely therapeutic difficulty was thereby addressed: the ability to rapidly detect treatment failures because of antibiotic-resistant bacteria. Methicillin-resistant (MRSA) and methicillin-sensitive (MSSA) were used and for infecting mice, while natural MSSA infection was studied in humans. Samples of bacterial growth media, the blood of infected mice and of humans were analyzed with combined Gas Chromatography/Mass Spectrometry. Multivariate data analysis was used to reveal the metabolic profiles of infection and the responses to different antibiotic treatments. experiments resulted in the detection of 256 putative metabolites and mice infection experiments resulted in the detection of 474 putative metabolites. Importantly, ineffective and effective antibiotic treatments were differentiated already two hours after treatment start in both experimental systems. That is, the ineffective treatment of MRSA using cloxacillin and untreated controls produced one metabolic profile while all effective treatment combinations using cloxacillin or vancomycin for MSSA or MRSA produced another profile. For further evaluation of the concept, blood samples of humans admitted to intensive care with severe sepsis were analyzed. One hundred thirty-three putative metabolites differentiated severe MSSA sepsis (n = 6) from severe sepsis (n = 10) and identified treatment responses over time. Combined analysis of human, , and mice samples identified 25 metabolites indicative of effective treatment of sepsis. Taken together, this study provides a proof of concept of the utility of analyzing metabolite patterns in blood for early differentiation between ineffective and effective antibiotic treatment in acute infections.
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| 6. |
- Avican, Kemal, et al.
(författare)
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Reprogramming of Yersinia from Virulent to Persistent Mode Revealed by Complex In Vivo RNA-seq Analysis
- 2015
-
Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- We recently found that Yersinia pseudotuberculosis can be used as a model of persistent bacterial infections. We performed in vivo RNA-seq of bacteria in small cecal tissue biopsies at early and persistent stages of infection to determine strategies associated with persistence. Comprehensive analysis of mixed RNA populations from infected tissues revealed that Y. pseudotuberculosis undergoes transcriptional reprogramming with drastic down-regulation of T3SS virulence genes during persistence when the pathogen resides within the cecum. At the persistent stage, the expression pattern in many respects resembles the pattern seen in vitro at 26oC, with for example, up-regulation of flagellar genes and invA. These findings are expected to have impact on future rationales to identify suitable bacterial targets for new antibiotics. Other genes that are up-regulated during persistence are genes involved in anaerobiosis, chemotaxis, and protection against oxidative and acidic stress, which indicates the influence of different environmental cues. We found that the Crp/CsrA/RovA regulatory cascades influence the pattern of bacterial gene expression during persistence. Furthermore, arcA, fnr, frdA, and wrbA play critical roles in persistence. Our findings suggest a model for the life cycle of this enteropathogen with reprogramming from a virulent to an adapted phenotype capable of persisting and spreading by fecal shedding.
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| 7. |
- Borg, Andreas, et al.
(författare)
-
Analysing mathematical programming schemes using different lenses
- 2023
-
Ingår i: Nordisk matematikkdidaktikk, NOMAD. - : University of Gothenburg, Sweden. - 1104-2176. ; 28:3–4, s. 199-219
-
Tidskriftsartikel (refereegranskat)abstract
- The use of programming in mathematics education is undergoing a renaissanceand, in this paper, we analyse students’ handling of programming in mathematicsusing the Instrumental approach as a theoretical lens. We are especially interestedin analysing the development of mental schemes using two analytical frameworkswhich are compared and contrasted according the idea of networking theories. Thestudy illustrates that the frameworks’ detail of richness can have both advantagesand disadvantages and that one of the frameworks are more customed to be appliedwhen analysing students’ instrumental genesis concerning the use of a programmingenvironment as a mathematical artefact.
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| 8. |
- Borg, Andreas
(författare)
-
Designing for the incorporation of programming in mathematical education : Programming as an instrument for mathematical problem solving
- 2021
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study explored Swedish upper secondary school students’ use of programming for mathematical purposes. The aim of the study was to investigate the process through which students learn how to use a programming environment as a technical artefact during mathematical problem solving and how the orchestration of such learning situations could facilitate this process. In order to study the students’ use of the programming environment, design-based research was used as the main methodological approach. The design involved the development of specific mathematical tasks to be tried out with students, as well as the orchestration of the learning situation within the classroom e.g., by preparing scaffolding to be offered to the students. The subsequent implementation of the design was analysed so that, in accordance with the cyclic approach of design-based research, it could be revised ahead of the following design cycle. The study involved two complete design cycles. In the study, the Instrumental Approach was used as the theoretical framework and the instrumental genesis of the students in using a programming environment for mathematical purposes was thus of special interest. In order to analyse this process and the associated mental schemes developed by the students, Vergnaud’s concept of scheme served as an analytical framework. The findings revealed how the students, despite having basic knowledge in programming, experienced several difficulties when trying to use the programming environment as a technical mathematical artefact. These difficulties were related both to the fact that the mathematical affordances offered by the programming environment were unclear to many of the students, as well as to the handling of more specific computational concepts such as nested loops. The findings also revealed that the transformation of mathematical notations and ideas into programming code caused students difficulties.
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| 9. |
- Borg, Andreas, et al.
(författare)
-
Programming as a mathematical instrument : the implementation of an analytic framework
- 2020
-
Ingår i: Mathematics Education in the Digital Age (MEDA) PROCEEDINGS. - 9783950463057 ; , s. 435-442
-
Konferensbidrag (refereegranskat)abstract
- This paper relates to an ongoing project using design-based research as a methodol- ogical approach in which students with no prior experiences of using programming as a mathematical tool are observed trying to solve mathematical problems with the help of programming. The Instrumental Approach is used as conceptual framework in which the concept of instrumental genesis describes the process where the programming environment as an artefact together with student-developed mental schemes forms an instrument in order to solve mathematical problems. The development of schemes is of special interest in this paper where Vergnaud’s components of a scheme provide a framework for analysing transcripts of talk between student pairs and the programming code that they generate.
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| 10. |
- Brunström, Mats, 1960-, et al.
(författare)
-
Computer-aided assessment based on dynamic mathematics investigations
- 2020
-
Ingår i: Proceedings of the Tenth ERME Topic Conference (ETC 10) on Mathematics Education in the Digital Age (MEDA), 16-18 September 2020 in Linz, Austria. - Linz, Austria.
-
Konferensbidrag (refereegranskat)abstract
- In the poster, we will present a planned study focusing on the design of DMS tasks and elaborated feedback within a CAA system. The study will be conducted in a first year engineering mathematics course during autumn 2020.
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| 11. |
- Brunström, Mats, 1960-, et al.
(författare)
-
Designing for a combined use of a dynamic mathematics software environment and a computer-aided assessment system
- 2022
-
Ingår i: Proceedings of the Twelfth Congress of the European Research Society in Mathematics Education (CERME12). - : ERME.
-
Konferensbidrag (refereegranskat)abstract
- This paper reports on a pilot study with the focus on (re)design of a digitized task environment utilizing two types of technology – a dynamic mathematics software and a computer-aided assessment system. The data consist of responses from 256 first year engineering students, taking their first Calculus course, on two different types of task. The results are discussed in relation to (re)design of tasks as well as possible feedback design options to enable a formative assessment approach.
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| 12. |
- Brunström, Mats, 1960-, et al.
(författare)
-
Designing Prediction Tasks in a Mathematics Software Environment
- 2015
-
Ingår i: The International Journal for Technology in Mathematics Education. - : RESEARCH INFORMATION LTD. - 1744-2710 .- 2045-2519. ; 22:1, s. 3-18
-
Tidskriftsartikel (refereegranskat)abstract
- There is a recognized need in mathematics teaching for new kinds of task which exploit the affordances provided by new technology. This paper focuses on the design of prediction tasks to foster student reasoning about exponential functions in a mathematics software environment. It draws on the first iteration of a design based research study conducted by the authors in collaboration with four upper secondary school teachers. A task sequence was trailed with four 10th grade classes, involving a total of 85 students. The research process pinpointed key didactical variables that proved crucial in designing these tasks. As well as being useful in the task design process, the didactical variables were found to be valuable in the processes of analysis and revision. While the didactical variables identified a priori were informed by the research literature concerning reasoning and functions, those identified a posteriori deal mainly with scaffolding issues that emerged.
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| 13. |
- Brunström, Mats, 1960-, et al.
(författare)
-
GeoGebra - A Tool to Create Favorable Learning Situations with Emphasize on Logical Reasoning and Communication
- 2009
-
Konferensbidrag (populärvet., debatt m.m.)abstract
- Logic reasoning and communication are general competencies, important in all areas of mathematics. We think that one of the major advantages of GeoGebra is the possibility to create favorable learning situations for these competencies. We would like to investigate these possibilities. Our main interest is to find out how students use logic reasoning and how they communicate when they work in pairs with GeoGebra. We think that investigating the validity of certain geometrical statements is a kind of task appropriate for this purpose
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| 14. |
- Brunström, Mats, 1960-, et al.
(författare)
-
Orchestration of mathematical discussions drawing on students’ computer-based work
- 2017
-
Ingår i: ICT in mathematics education: the future and the realities. - Göteborg : Svensk förening för MatematikDidaktisk Forskning - SMDF. - 9789198402407 ; , s. 77-87
-
Konferensbidrag (refereegranskat)abstract
- Research points out the importance of following up students’ work on computerbasedtasks with whole-class discussions in which students play a central role.However, at the same time, research highlights the challenge for teachers in orchestratingsuch follow-up discussions. This paper examines whether an establishedmodel developed as guidance for teachers to orchestrate mathematical whole-classdiscussions (Stein, Engle, Smith & Hughes, 2008) could be useful in this educationalsetting. Students’ written responses to two different tasks are the main data used toexamine the model. The results indicate that the model has great potential to guidethese follow-up discussions
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| 15. |
- Costa, Tiago R. D., et al.
(författare)
-
Active type III translocon assemblies that attenuate Yersinia virulence
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Type III secretion enables bacteria to intoxicate eukaryotic cells with anti-host effectors. A class of secreted cargo are the two hydrophobic translocators that form a translocon pore in the host cell plasma membrane through which the translocated effectors may gain cellular entry. In pathogenic Yersinia, YopB and YopD shape this translocon pore. Here, four in cis yopD mutations were constructed to disrupt a predicted a-helix motif at the C-terminus. Mutants YopDI262P and YopDK267P poorly localised Yop effectors into target eukaryotic cells and failed to resist uptake and killing by immune cells. These defects were due to deficiencies in host-membrane insertion of the YopD-YopB translocon. Mutants YopDA263P and YopDA270P had no measurable in vitro translocation defect, even though they formed smaller translocon pores in erythrocyte membranes. Despite this, all four mutants were attenuated in a mouse infection model. Hence, YopD variants have been generated that can spawn translocons capable of targeting effectors in vitro, yet were bereft of any lethal effect in vivo. It is therefore probable that an active translocon makes a range of contributions during bacteria-host cell contact that extends beyond effector delivery per se.
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| 16. |
- Costa, Tiago R. D., et al.
(författare)
-
Coiled-coils in the YopD translocator family : A predicted structure unique to the YopD N-terminus contributes to full virulence of Yersinia pseudotuberculosis
- 2012
-
Ingår i: Infection, Genetics and Evolution. - : Elsevier. - 1567-1348 .- 1567-7257. ; 12:8, s. 1729-1742
-
Tidskriftsartikel (refereegranskat)abstract
- Pathogenic Yersinia all harbor a virulence plasmid-encoded Ysc–Yop T3SS. In this system, translocator function is performed by the hydrophobic proteins YopB and YopD. With the goal to better understand how YopD orchestrates yop-regulatory control, translocon pore formation and Yop effector translocation, we performed an in silico prediction of coiled-coil motifs in YopD and YopD-like sequences from other bacteria. Of interest was a predicted N-terminal coiled-coil that occurred solely in Yersinia YopD sequences. To investigate if this unique feature was biologically relevant, two in cis point mutations were generated with a view to disrupting this putative structure. Both mutants maintained full T3SS function in vitro in terms of environmental control of Yops synthesis and secretion, effector toxin translocation and evasion of phagocytosis and killing by cultured immune cells. However, these same mutants were attenuated for virulence in a murine oral-infection model. The cause of this tardy disease progression is unclear. However, these data indicate that any structural flaw in this element unique to the N-terminus will subtly compromise an aspect of YopD biology. Sub-optimal T3SSs are then formed that are unable to fortify Yersinia against attack by the host innate and adaptive immune response.
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| 17. |
- Costa, Tiago, et al.
(författare)
-
Type III secretion translocon assemblies that attenuate Yersinia virulence
- 2013
-
Ingår i: Cellular Microbiology. - : Wiley-Blackwell. - 1462-5814 .- 1462-5822. ; 15:7, s. 1088-1110
-
Tidskriftsartikel (refereegranskat)abstract
- Type III secretion enables bacteria to intoxicate eukaryotic cells with anti-host effectors. A class of secreted cargo are the two hydrophobic translocators that form a translocon pore in the host cell plasma membrane through which the translocated effectors may gain cellular entry. In pathogenic Yersinia, YopB and YopD shape this translocon pore. Here, four in cis yopD mutations were constructed to disrupt a predicted α-helix motif at the C-terminus. Mutants YopD(I262P) and YopD(K267P) poorly localized Yop effectors into target eukaryotic cells and failed to resist uptake and killing by immune cells. These defects were due to deficiencies in host-membrane insertion of the YopD-YopB translocon. Mutants YopD(A263P) and YopD(A270P) had no measurable in vitro translocation defect, even though they formed smaller translocon pores in erythrocyte membranes. Despite this, all four mutants were attenuated in a mouse infection model. Hence, YopD variants have been generated that can spawn translocons capable of targeting effectors in vitro, yet were bereft of any lethal effect in vivo. Therefore, Yop translocators may possess other in vivo functions that extend beyond being a portal for effector delivery into host cells.
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| 18. |
- Fahlgren, Anna, et al.
(författare)
-
Cell type-specific effects of Yersinia pseudotuberculosis virulence effectors
- 2009
-
Ingår i: Cellular Microbiology. - : Hindawi Limited. - 1462-5814 .- 1462-5822. ; 11:12, s. 1750-1767
-
Tidskriftsartikel (refereegranskat)abstract
- One important feature of Yersinia pseudotuberculosis that enables resistance against the host immune defence is delivery of the antiphagocytic effectors YopH and YopE into phagocytic cells. The tyrosine phosphatase YopH influences integrin signalling, and YopE impairs cytoskeletal dynamics by inactivating Rho GTPases. Here, we report the impact of these effectors on internalization by dendritic cells (DCs), which internalize antigens to orchestrate host immune responses. We found that this pathogen resists internalization by DCs via YopE. YopH that is important for blocking phagocytosis by macrophages and neutrophils and which is also present inside the DCs does not contribute to the resistance. However, the YopH targets Fyb and p130Cas show higher expression levels in macrophages than in DCs. Furthermore, live cell microscopy revealed that the cells internalize Y. pseudotuberculosis in different ways: the macrophages utilize a locally restricted receptor-mediated zipper mechanism, whereas DCs utilize macropinocytosis involving constitutive ruffling that randomly catches bacteria into membrane folds. We conclude that YopH impacts early phagocytic signalling from the integrin receptor to which the bacterium binds and that this tight receptor-mediated stimulation is absent in DC macropinocytosis. Inactivation of cytoskeletal dynamics by YopE affects ruffling activity and hence also internalization. The different modes of internalization can be coupled to the major functions of these respective cell types: elimination by phagocytosis and antigen sampling.
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| 19. |
- Fahlgren, Anna, et al.
(författare)
-
Colonization of cecum is important for development of persistent infection by Yersinia pseudotuberculosis
- 2014
-
Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 82:8, s. 3471-3482
-
Tidskriftsartikel (refereegranskat)abstract
- Yersiniosis is a human disease caused by the bacterium Yersinia pseudotuberculosis or Yersinia enterocolitica. The infection is usually resolved but can lead to postinfectious sequelae, including reactive arthritis and erythema nodosum. The commonly used Yersinia mouse infection model mimics acute infection in humans to some extent but leads to systemic infection and eventual death. Here, we analyzed sublethal infection doses of Y. pseudotuberculosis in mice in real time using bioluminescent imaging and found that infections using these lower doses result in extended periods of asymptomatic infections in a fraction of mice. In a search for the site for bacterial persistence, we found that the cecum was the primary colonization site and was the site where the organism resided during a 115-day infection period. Persistent infection was accompanied by sustained fecal shedding of cultivable bacteria. Cecal patches were identified as the primary site for cecal colonization during persistence. Y. pseudotuberculosis bacteria were present in inflammatory lesions, in localized foci, or as single cells and also in neutrophil exudates in the cecal lumen. The chronically colonized cecum may serve as a reservoir for dissemination of infection to extraintestinal sites, and a chronic inflammatory state may trigger the onset of postinfectious sequelae. This novel mouse model for bacterial persistence in cecum has potential as an investigative tool to unveil a deeper understanding of bacterial adaptation and host immune defense mechanisms during persistent infection.
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| 20. |
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| 21. |
- Fahlgren, Maria, 1966-, et al.
(författare)
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A Model for Task Design with Focus on Exploration,Explanation, and Generalization in a Dynamic GeometryEnvironment
- 2014
-
Ingår i: Technology, Knowledge and Learning. - : Springer. - 2211-1662 .- 2211-1670. ; 19:3, s. 287-315
-
Tidskriftsartikel (refereegranskat)abstract
- The increasing availability of new technologies in schools provides new possibilitiesfor the integration of technology in mathematics education. However, researchhas shown that there is a need for new kinds of task that utilize the affordances provided bynew technology. Numerous studies have demonstrated that dynamic geometry environmentsprovide opportunities for students to engage in mathematical activities such asexploration, conjecturing, explanation, and generalization. This paper presents a model fordesign of tasks that promote these kinds of mathematical activity, especially tasks thatfoster students to make generalizations. This model has been primarily developed to suitthe use of dynamic environments in tackling geometrical locus problems. The model wasinitially constructed in the light of previous literature. This initial model was used to designa concrete example of such a task situation which was tested in action through a case studywith two doctoral students. Findings from this case study were used to guide revision of theinitial model.
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| 22. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Connected classroom technology to monitor, select and sequence student responses
- 2021
-
Ingår i: Sustainable mathematics education in a digitalized world. - : Svensk förening för MatematikDidaktisk Forskning - SMDF. - 9789198402445 ; , s. 11-20
-
Konferensbidrag (refereegranskat)abstract
- This paper reports a study of teachers’ use of Connected classroom technology to prepare for whole-class discussions building on students’ computer-based work in mathematics. The study investigates four upper secondary school teachers’ management of time and progression during the phase of the lesson where students are working in pairs. The findings highlight various didactical choices made by the teachers. These choices and some related challenges are discussed
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| 23. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Designing example-generating tasks for a technology-rich mathematical environment
- 2023
-
Ingår i: International Journal of Mathematical Education in Science and Technology. - : Taylor & Francis. - 0020-739X .- 1464-5211. ; , s. 1-17
-
Tidskriftsartikel (refereegranskat)abstract
- This paper provides some insights into the use of example-generating tasks in the design of a technology-rich learning environment to enhance students’ mathematical thinking. The paper reports on an early stage of a design-based research project concerning the design of tasks and associated feedback utilising the affordances provided by a combined use of a dynamic mathematics software environment and a computer-aided assessment system. In example-generating tasks, students are asked to generate examples that fulfil certain conditions. Based on data in terms of examples generated by 491 first-year engineering students, taking a first course in calculus, the paper examines patterns of student response to three example-generating tasks. As a theoretical lens, the notions of dimensions of possible variation and associated ranges of permissible change are used. In light of the observed patterns, the paper provides some guiding principles for designing example-generating tasks and associated formative feedback to foster students’ mathematical understanding by enriching their example spaces. For example, this paper illustrates occasions where it might be instructive to start by asking for two examples, followed by adapted feedback before requesting a third example.
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| 24. |
- Fahlgren, Maria, 1966-
(författare)
-
Designing for the integration of dynamic software environments in the teaching of mathematics
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the challenge of integrating dynamic software environments into the teaching of mathematics. It investigates particular aspects of the design of tasks which employ this type of computer-based system, with a focus on improvement, both of the tasks themselves and of the design process through which they are developed and refined.The thesis reports two research projects: a small initial one preceding a larger main project. The initial case study, involving two graduate students in mathematics, develops a task design model for geometrical locus problems. The main study constitutes the first iteration of a design-based study, conducted in collaboration with four upper-secondary school teachers and their classes. It seeks to identify task design characteristics that foster students’ mathematical reasoning and proficient use of software tools, and examines teachers’ organisation of ‘follow-up’ lessons.The findings concern three particular aspects: features of tasks and task environment relevant to developing a specific plan of action for a lesson; orchestration of a particular task environment to support the instrumental genesis of specific dynamic software tools; how to follow up students’ work on computer-based tasks in a whole-class discussion.
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| 25. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Designing tasks and feedback utilizing a combination of a dynamic mathematics software and a computer-aided assessment system
- 2022
-
Ingår i: Proceedings of the 15th International Conference on Technology in Mathematics Teaching (ICTMT 15). - Aarhus : Danish School of Education, Aarhus Unviersity. - 9788775075256 ; , s. 272-279
-
Konferensbidrag (refereegranskat)abstract
- This paper reports on the planning of a design-based research (DBR) study, where the main aim is to develop principles in designing technology-enhanced learning environment utilizing a combination of a dynamic mathematics software (DMS) and a computer-aided assessment (CAA) system. The focus is on the design of tasks and automated feedback of high quality so as to enhance first year engineering students’ engagement in and conceptual understanding of mathematical contents. The paper outlines the rationale for the project and highlights theoretical aspects that will be considered in the study. Moreover, some findings from a pilot study that will inform the first cycle of the DBR study are presented.
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| 26. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Example-generating tasks in a computer-aided assessment system : Redesign based on student responses
- 2022
-
Ingår i: Proceedings of the 13<sup>th</sup> ERME Topic Conference (ETC13). - : Constantine the Philosopher University in Nitra. - 9788055819129 ; , s. 141-144
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Based on the patterns of response to an example-generating task, this paper provides suggestions onhow the task could be redesigned to enrich students’ example spaces in relation to the key ideasaddressed by the task. The participants are 236 first-year engineering students
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| 27. |
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| 28. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
How the word 'mathematical' influences students’ responses to explanation tasks in a dynamic mathematics software environment
- 2018
-
Ingår i: Proceedings of the Fifth ERME Topic Conference (ETC 5) on Mathematics Education in the Digital Age (MEDA). - Copenhagen, Denmark : University of Copenhagen. - 9788770787987 ; , s. 83-90
-
Konferensbidrag (refereegranskat)abstract
- Task design is a central issue in mathematics education, not least in relation to digital technology. This paper reports how a smal lbut significant change in wording affects students’ explanatory responses. The study is comparative and involves 229 10th grade students working on tasks designed for a dynamic mathematics software environment. The findings indicate that inclusion of the word ‘mathematical’ prompted students to use algebraic symbols and algebraic arguments, to a higher degree.
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| 29. |
- Fahlgren, Maria, 1966-
(författare)
-
Instrumental genesis concerning scales and scaling in a dynamic mathematics software environment
- 2015
-
Ingår i: Proceedings of the Ninth Congress of European Research in Mathematics Education. - Prague : European Society for Research in Mathematics Education. ; , s. 2347-2353
-
Konferensbidrag (refereegranskat)abstract
- It is recognized that the process in which an artefact becomes an instrument for a user, denoted as instrumental genesis, is a complex process. The aim of this paper is to identify elements of the process of instrumental genesis when students are dealing with scales and scaling issues in a dynamic mathematics software environment. This study involves four upper secondary school teachers and their classes. By observing the students’ instrumented techniques while working with tasks designed with a hypothetical instrumental genesis in mind, some key elements are identified.
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| 30. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Orchestrating whole-class discussions in mathematics using connected classroom technology
- 2019
-
Ingår i: Proceedings of the 14<sup>th</sup> International Conference on Technology in Mathematics Teaching - ICTMT 14. ; , s. 173-182
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports on the planning of a pilot study where the aim is to develop and investigate teaching practices, using connected classroom technology (CCT), to support formative classroom practices in mathematics. The focus is on the design of a teaching unit including a whole-class discussion drawing on students’ computer-based work. The paper outlines both generic and topicspecific theories underpinning the design. Moreover, findings from a previous study, in terms of student responses to a task developed for a dynamic mathematics software environment, are used in the planning. One important issue addressed in this paper is the sequencing of student responses to display and use as a basis for whole-class discussions.
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| 31. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Prospective teachers designing tasks for dynamic geometry environments
- 2022
-
Ingår i: Proceedings of the Twelfth Congress of the European Society for Research in Mathematics Education (CERME 12). - Bozen-Bolzano : Free University of Bozen-Bolzano. - 9791221025378
-
Konferensbidrag (refereegranskat)abstract
- The paper examines the quality of digitized tasks designed by 10 (small) groups of prospective upper secondary school teachers as part of a geometry course assignment. The results indicate that a small instructional intervention, addressing the planning and implementation of tasks in digitized task environments as well as how to stimulate students to make mathematical generalizations, led to a relatively high proportion (8 out of 10) of high-quality tasks designed by the prospective teachers.
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| 32. |
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| 33. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Student responses as a basis for whole class discussions in technology-rich environment
- 2020
-
Ingår i: Proceedings of the Tenth ERME topic Conference (ETC 10). - Linz, Austria. - 9783950463057 ; , s. 183-190
-
Konferensbidrag (refereegranskat)abstract
- This paper reports a study of four upper secondary school teachers’ use of Connected Classroom Technology to select student responses to computer-based activities, and to use these responses to launch successive stages of a planned whole-class discussion. Although the preparation for the class discussion was quite successful, it was a challenge for the teachers to conduct the whole-class discussion, particularly in posing specific questions based on appropriate student responses.
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| 34. |
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| 35. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Technology-rich assessment in mathematics
- 2021
-
Ingår i: Mathematics Education in the Digital Age. - : Taylor & Francis. - 9781000390766 - 9780367684518 ; , s. 69-83
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 36. |
- Fahlgren, Maria, 1966-, et al.
(författare)
-
Using slider tools to explore and validate
- 2015
-
Ingår i: CERME9 Proceedings of the Ninth Congress of the European Society for Research in Mathematics Education. - 9788072908448
-
Konferensbidrag (refereegranskat)
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| 37. |
- Juter, Kristina, et al.
(författare)
-
The space between pre-service primary teachers’ first year status and their goals
- 2018
-
Ingår i: Perspectives on professional development of mathematics teachers. ; , s. 222-223
-
Bokkapitel (populärvet., debatt m.m.)abstract
- Students’ mathematics teacher identity is formed in various settings. A study with 45 pre-service students in their first year of education was conducted as part of alongitudinal study of year 4-6 mathematics teachers’ identity formation, to study the development during their education in terms of mathematical knowledge, pupils’ learning and the teacher role. Questionnaires and interviews were used to collect data. The result shows that many students were reluctant to use mathematics and had conceptions that may mislead pupils. The students’ learning focus was less on pupils’ learning than mathematics and teacher role, but theirideal teacher focused on pupils’ learning.
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| 38. |
- Lindell, Kristoffer, 1979-, et al.
(författare)
-
Lipopolysaccharide O-Antigen Prevents Phagocytosis of Vibrio anguillarum by Rainbow Trout (Oncorhynchus mykiss) Skin Epithelial Cells
- 2012
-
Ingår i: PLOS ONE. - San Francisco : Public Library of Science. - 1932-6203. ; 7:5, s. e37678-
-
Tidskriftsartikel (refereegranskat)abstract
- Colonization of host tissues is a first step taken by many pathogens during the initial stages of infection. Despite the impact of bacterial disease on wild and farmed fish, only a few direct studies have characterized bacterial factors required for colonization of fish tissues. In this study, using live-cell and confocal microscopy, rainbow trout skin epithelial cells, the main structural component of the skin epidermis, were demonstrated to phagocytize bacteria. Mutant analyses showed that the fish pathogen Vibrio anguillarum required the lipopolysaccharide O-antigen to evade phagocytosis and that O-antigen transport required the putative wzm-wzt-wbhA operon, which encodes two ABC polysaccharide transporter proteins and a methyltransferase. Pretreatment of the epithelial cells with mannose prevented phagocytosis of V. anguillarum suggesting that a mannose receptor is involved in the uptake process. In addition, the O-antigen transport mutants could not colonize the skin but they did colonize the intestines of rainbow trout. The O-antigen polysaccharides were also shown to aid resistance to the antimicrobial factors, lysozyme and polymyxin B. In summary, rainbow trout skin epithelial cells play a role in the fish innate immunity by clearing bacteria from the skin epidermis. In defense, V. anguillarum utilizes O-antigen polysaccharides to evade phagocytosis by the epithelial cells allowing it to colonize rapidly fish skin tissues.
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| 39. |
- Mahmud, A. K. M. Firoj, et al.
(författare)
-
Genome-Scale Mapping Reveals Complex Regulatory Activities of RpoN in Yersinia pseudotuberculosis
- 2020
-
Ingår i: mSystem. - 2379-5077. ; 5:6
-
Tidskriftsartikel (refereegranskat)abstract
- RpoN, an alternative sigma factor commonly known as σ54, is implicated in persistent stages of Yersinia pseudotuberculosis infections in which genes associated with this regulator are upregulated. We here combined phenotypic and genomic assays to provide insight into its role and function in this pathogen. RpoN was found essential for Y. pseudotuberculosis virulence in mice, and in vitro functional assays showed that it controls biofilm formation and motility. Mapping genome-wide associations of Y. pseudotuberculosis RpoN using chromatin immunoprecipitation coupled with next-generation sequencing identified an RpoN binding motif located at 103 inter- and intragenic sites on both sense and antisense strands. Deletion of rpoN had a large impact on gene expression, including downregulation of genes encoding proteins involved in flagellar assembly, chemotaxis, and quorum sensing. There were also clear indications of cross talk with other sigma factors, together with indirect effects due to altered expression of other regulators. Matching differential gene expression with locations of the binding sites implicated around 130 genes or operons potentially activated or repressed by RpoN. Mutagenesis of selected intergenic binding sites confirmed both positive and negative regulatory effects of RpoN binding. Corresponding mutations of intragenic sense sites had less impact on associated gene expression. Surprisingly, mutating intragenic sites on the antisense strand commonly reduced expression of genes carried by the corresponding sense strand.
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| 40. |
- Nelson, Maria, 1979-
(författare)
-
Host responses to malaria and bacterial co-infections
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The two main causes of child mortality and morbidity in Africa are malaria and invasive bacterial diseases. In addition, co-infections in sub-Saharan Africa are the rule rather than the exception. However, not much is known about the host-pathogen interaction during a concomitant infection or how it affects the outcome of disease.In order to study the immunological responses during malaria and bacterial co-infections, we established a co-infection mouse model. In these studies we used two pathogenic bacteria found in malaria co-infected patients: Streptococcus pneumoniae and Relapsing fever Borrelia duttonii.Hosts co-infected with malaria and Borrelia showed greatly increased spirochetal growth but low parasite densities. In addition, the co-infected hosts presented symptoms of experimental-cerebral malaria, in an otherwise unsusceptible mouse model. This was found to be a consequence of a dysregulated immune response due to loss of timing and control over regulatory mechanisms in antigen presenting cells thus locking the host in an inflammatory response. This results in inflammation, severe anemia, internal organ damage and pathology of experimental cerebral malaria.On the other hand, in the malaria - S. pneumoniae co-infection model we found that co-infected hosts cleared the bacterium much more efficiently than the single infected counterpart. This efficiency of clearance showed to be neutrophil dependent. Furthermore, in vitro studies revealed that neutrophils isolated from malaria-infected hosts present an altered migratory effect together with a significantly increased capacity to kill S. pneumoniae. This suggests that a malaria infection primes neutrophils to kill S. pneumoniae more efficiently.Furthermore, a study was carried out on plasma samples from Rwandan children under the age of five, on which a full metabolomics profile was performed. We showed that these children could be divided in different disease categories based on their metabolomics profile and independent of clinical information. Additionally, the mild malaria group could further be divided in two sub-groups, in which one had a metabolomic profile resembling that of severe malaria infected patients. Based on this, metabolite profiling could be used as a diagnostic tool to determine the distinct phase, or severity of a malaria infection, identify risk patients and provide helpful and correct therapy.
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| 41. |
- Nilsson, Anna, et al.
(författare)
-
Fluid pressure induces osteoclast differentiation comparably to titanium particles but through a molecular pathway only partly involving TNFa
- 2012
-
Ingår i: Journal of Cellular Biochemistry. - : Wiley-Blackwell. - 0730-2312 .- 1097-4644. ; 113:4, s. 1224-1234
-
Tidskriftsartikel (refereegranskat)abstract
- In contrast to the well-understood inflammatory pathway driven by TNFa, by which implant-derived particles induce bone resorption, little is known about the process in which loosening is generated as a result of force-induced mechanical stimulus at the boneimplant interface. Specifically, there is no knowledge as to what cells or signaling pathways couple mechanical stimuli to bone resorption in context of loosening. We hypothesized that different stimuli, i.e., fluid flow versus wear particles, act through different cytokine networks for activation and localization of osteoclasts. By using an animal model in which osteoclasts and bone resorption were induced by fluid pressure or particles, we were able to detect distinct differences in osteoclast localization and inflammatory gene expression between fluid pressure and titanium particles. Fluid pressure recruits and activates osteoclasts with bone marrow contact away from the fluid pressure exposure zone, whereas titanium particles recruit and activate osteoclasts in areas in direct contact to particles. Fluid pressure induced weaker expression of the selected inflammatory related genes, although the eventual degree of osteoclast induction was similar in both models. Using TNFaRa (4?mg/kg) (Enbrel) and dexamethasone (2?mg/kg) as specific and more general suppressors of inflammation we showed that the TNFaRa failed to generate statistically impaired osteoclast generation while dexamethasone was much more potent. These results demonstrate that fluid pressure induces osteoclasts at a different localization than titanium particles by a molecular pathway less associated with TNFa and the innate system, which open up for other pathways controlling pressure induced osteoclastogenesis.
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| 42. |
- Normark, Johan, et al.
(författare)
-
Maladjusted Host Immune Responses Induce Experimental Cerebral Malaria-Like Pathology in a Murine Borrelia and Plasmodium Co-Infection Model
- 2014
-
Ingår i: PLOS ONE. - : PLOS ONE. - 1932-6203. ; 9:7
-
Tidskriftsartikel (refereegranskat)abstract
- In the Plasmodium infected host, a balance between pro- and anti-inflammatory responses is required to clear the parasites without inducing major host pathology. Clinical reports suggest that bacterial infection in conjunction with malaria aggravates disease and raises both mortality and morbidity in these patients. In this study, we investigated the immune responses in BALB/c mice, co-infected with Plasmodium berghei NK65 parasites and the relapsing fever bacterium Borrelia duttonii. In contrast to single infections, we identified in the co-infected mice a reduction of L-Arginine levels in the serum. It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium. Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells. Co-infected mice further showed an increased inflammatory response through IL-1 beta and TNF-alpha, as well as inability to down regulate the same through IL-10. In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells. Our study shows that a situation mimicking experimental cerebral malaria (ECM) is induced in co-infected mice due to loss of timing and control over regulatory mechanisms in antigen presenting cells.
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| 43. |
-
Perspectives on Professional development of mathematics teachers : Proceedings of MDIF11: The 11th Swedish Mathematics Education Research Seminar, 23–28 January 2018, Karlstad, Sweden
- 2018
-
Proceedings (redaktörskap) (refereegranskat)abstract
- This volume contains the proceedings of MADIF 11, the eleventh Swedish Mathematics Education Research Seminar, held in Karlstad, January 23–24, 2018. The theme for this seminar was Perspectives on professional development of mathematics teachers. The MADIF seminars are organised by the Swedish Society for Research in Mathematics Education (SMDF). MADIF aims to enhance the opportunities for discussion of research and exchange of perspectives, amongst junior researchers and between junior and senior researchers in the field. The first seminar took place in January 1999 at Lärarhögskolan in Stockholm and included the constitution of the SMDF. The list shows all MADIF seminars.MADIF 1, 1999, StockholmMADIF 2, 2000, GöteborgMADIF 3, 2002, NorrköpingMADIF 4, 2004, MalmöMADIF 5, 2006, MalmöMADIF 6, 2008, StockholmMADIF 7, 2010, StockholmMADIF 8, 2012, UmeåMADIF 9, 2014, UmeåMADIF 10, 2016, KarlstadMADIF 11, 2018, KarlstadPrinted proceedings of the seminars are available for all but the very first meeting. This volume and the proceedings from MADIF 9 and 10 are also available digitally.The members of the MADIF 11 programme committee were Johan Häggström (University of Gothenburg), Yvonne Liljekvist (Karlstad University), Jonas Bergman Ärlebäck (Linköping University), Maria Fahlgren (Karl-stad University) and Oduor Olande (Linneaus University ). The local organisers were Yvonne Liljekvist and Mats Brunström (Karlstad University). The programme of MADIF 11 included two plenary lectures by invited speakers JeungSuk Pang and Peter Liljedahl. As before, MADIF works with a format of full 10 page papers and with short presentations. This year the number of full papers was eighteen, which is twice as many as in MADIF 10.The number of short presentations were eleven. The seminar also had one symposium, where three papers around a common theme were presented and dis-cussed. As the research seminars have sustained the idea of offering formats for presentation that enhance feedback and exchange, the paper presentations are organised as discussion sessions based on points raised by an invited reactor. The organising committee would like to express its thanks to the following col-leagues for their commitment to the task of being reactors and moderators: Abdel Seidouvy, Anette Bagger, Cecilia Kilhamn, Hanna Palmér, Jan Olsson, Jöran Petersson, Kajsa Bråting, Kirsti Hemmi, Kristina Juter, Linda Marie Ahl, Lotta Wedman, Mette Susanne Andresen, Mirela Vinerean Bernhoff, Nils Buchholz, Ola Helenius, Olaf Knapp, Peter Frejd, Peter Nyström and Tomas Bergqvist.This volume comprises summaries of the two plenary addresses, 18 research reports (papers), one symposia and abstracts for the eleven short presentations. In a rigorous two-step review process for presentation and publication, all papers were peer-reviewed by two or three researchers. Short presentation contributions were reviewed by members of the programme committee. Since 2010, the MADIF Proceedings have been designated scientific level 1 in the Norwegian list of authorised publication channels available at http://dbh.nsd.uib.no/kanaler/.The editors are grateful to the following colleagues for providing reviews: Abdel Seidouvy, Allan Tarp, Andreas Ryve, Anette Bagger, Angelika Kullberg, Anna Teledahl, Anna-Lena Ekdahl, Arne Engström, Barbro Grevholm, Björn Textorius, Camilla Björklund, Cecilia Kilhamn, Ceclilia Segerby, Cristina Skodras, Cristina Svensson, Djamshid Farahani, Eva Taflin, Frode Rønning, Gerd Brandell, Hanna Palmér, Hamid Asghari, Helena Roos, Håkan Lennerstad, Håkan Sollerwall, Ida Bergvall, Jan Olsson, Jannika Lindwall, Joakim Samuelsson, Jonas Dahl, Jorryt van Bommel, Judy Sayers, Jöran Petersson, Kajsa Bråting, Karolina Muhrman, Kenneth Ruthven, Kirsti Hemmi, Kris-tina Juter, Lars Madej, Leslie Jiménez, Linda Marie Ahl, Lotta Wedman, Madis Lepik, Maike Schindler, Magnus Österholm, Maria Alkhede, Maria Larsson, Maria Reis, Marie Tanner, Margareta Engvall, Mathias Norqvist, Mette Susanne Andresen, Morten Blomhøj, Ola Helenius, Olaf Knapp, Paul Andrews, Per Nilsson, Peter Frejd, Peter Nyström, Reidar Mosvold, Robert Gunnarsson, Suela Kacerja, Takashi Kawakami, Thomas Lingefjärd, Tomas Bergqvist, Troels Lange and Uffe Thomas Jankvist.The organising committee and the editors would like to express their grati-tude to the organisers of Matematikbiennalen 2018 for financially supporting the seminar. Finally we would like to thank all participants of MADIF 11 for sustaining their engagement in an intense scholarly activity during the seminar with its tight timetable, and for contributing to an open, positive and friendly atmosphere.
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| 44. |
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| 45. |
- Schneiders, Stephan, et al.
(författare)
-
Spatiotemporal Variations in Growth Rate and Virulence Plasmid Copy Number during Yersinia pseudotuberculosis Infection : Growth rate and plasmid copy number during Yersinia infection
- 2021
-
Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522.
-
Tidskriftsartikel (refereegranskat)abstract
- Pathogenic Yersinia spp. depend on the activity of a potent virulence plasmid-encoded ysc/yop type 3 secretion system (T3SS) to colonize hosts and cause disease. It was recently shown that Y. pseudotuberculosis up-regulates the virulence plasmid copy number (PCN) during infection and the resulting elevated gene dose of plasmid-encoded T3SS genes is essential for virulence. When and how this novel regulatory mechanism is deployed and regulates the replication of the virulence plasmid during infection is unknown. In the current study, we applied droplet digital PCR (ddPCR) to investigate the dynamics of Y. pseudotuberculosis virulence PCN variations and growth rates in infected mouse organs. We demonstrated that both PCN and growth varied in different tissues and over time throughout the course of infection, indicating that the bacteria adapted to discrete microenvironments during infection. The PCN was highest in Peyer’s Patches and caecum during the clonal invasive phase of the infection, while the fastest growth rates were found in the draining mesenteric lymph nodes. In deeper, systemic organs, the PCN was lower and more modest growth rates were recorded. Our study indicates that increased gene dosage of the plasmid-encoded T3SS genes is most important early in the infection during invasion of the host. The described ddPCR approach will greatly simplify analyses of PCN, growth dynamics, and bacterial loads in infected tissues, and will be readily applicable to other infection models.
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| 46. |
- Schneiders, Stephan, et al.
(författare)
-
Spatiotemporal Variations in Growth Rate and Virulence Plasmid Copy Number during Yersinia pseudotuberculosis Infection
- 2021
-
Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 89:4
-
Tidskriftsartikel (refereegranskat)abstract
- Pathogenic Yersinia spp. depend on the activity of a potent virulence plasmid-encoded ysc/yop type 3 secretion system (T3SS) to colonize hosts and cause disease. It was recently shown that Yersinia pseudotuberculosis upregulates the virulence plasmid copy number (PCN) during infection and that the resulting elevated gene dose of plasmid-encoded T3SS genes is essential for virulence. When and how this novel regulatory mechanism is deployed and regulates the replication of the virulence plasmid during infection is unknown. In the present study, we applied droplet digital PCR (ddPCR) to investigate the dynamics of Y. pseudotuberculosis virulence PCN variations and growth rates in infected mouse organs. We demonstrated that both PCN and growth varied in different tissues and over time throughout the course of infection, indicating that the bacteria adapted to discrete microenvironments during infection. The PCN was highest in Peyer's patches and cecum during the clonal invasive phase of the infection, while the highest growth rates were found in the draining mesenteric lymph nodes. In deeper, systemic organs, the PCN was lower and more modest growth rates were recorded. Our study indicates that increased gene dosage of the plasmid-encoded T3SS genes is most important early in the infection during invasion of the host. The described ddPCR approach will greatly simplify analyses of PCN, growth dynamics, and bacterial loads in infected tissues and will be readily applicable to other infection models.
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| 47. |
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| 48. |
- Szabo, Attila, fil.dr. 1965-, et al.
(författare)
-
Prospective teachers constructing dynamic geometry activities in order to challenge gifted pupils
- 2022
-
Ingår i: On the Road to Mathematical Expertise and Innovation. - Münster : WTM – Verlag für wissenschaftliche Texte und Medien. - 9783959872263 - 9783959872157 ; , s. 265-271
-
Konferensbidrag (refereegranskat)abstract
- Described as fundamentally egalitarian, the Swedish educational system has, until recently, accorded little attention to gifted pupils. We investigated the effects of an instructional intervention for prospective teachers (PTs), i.e., a seminar about mathematical giftedness and problems appealing to gifted pupils. The PTs used dynamic geometry software (DGS) to construct activities for pupils in mixed-ability classrooms. The results indicate that 9 of 10 activities addressed some main characteristics of the gifted, importantly, the ability to generalize mathematical relationships.
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| 49. |
- Szabo, Attila, et al.
(författare)
-
Surveying prospective teachers’ conceptions of GeoGebra when constructing mathematical activities for pupils
- 2020
-
Ingår i: Proceedings of the 10th ERME Topic Conference (ETC 10) on Mathematics Education in the Digital Age (MEDA), 16-18 September 2020 in Linz, Austria. - Linz : Johannes Kepler University. - 9783950463057
-
Konferensbidrag (refereegranskat)abstract
- In this poster, we present an ongoing study about prospective mathematics teachers' conceptions about the relationship between mathematics, problem-solving and GeoGebra. The context of our study is a curriculum reform in Sweden that emphasizes the use of digital tools in mathematics education. In that respect, we will investigate prospective upper-secondary teachers´ conceptions when participating in a geometry course at the university level. During the course, participants will construct mathematical activities for pupils by using GeoGebra.
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| 50. |
- Taheri, Nayyer, et al.
(författare)
-
Accumulation of virulence-associated proteins in Campylobacter jejuni Outer Membrane Vesicles at human body temperature
- 2019
-
Ingår i: Journal of Proteomics. - : Elsevier BV. - 1874-3919 .- 1876-7737. ; 195, s. 33-40
-
Tidskriftsartikel (refereegranskat)abstract
- Campylobacter jejuni is the major cause of bacterial gastroenteritis in humans. In contrast, colonization in avian hosts is asymptomatic. Body temperature differs between human (37 °C) and avian (42 °C) hosts, and bacterial growth in 37 °C is therefore a potential cue for higher virulence properties during human infection. The proteome of the bacteria was previously shown to be altered by temperature. Here we investigated whether temperature has an effect on the C. jejuni outer membrane vesicle (OMV) proteome, as OMVs are considered to be bacterial vehicles for protein delivery and might play a role during infection. OMVs isolated from C. jejuni strain 81-176 grown at 37 °C and 42 °C were analyzed by LC-ESI-MS/MS. 181 proteins were detected in both sample groups, one protein was exclusively present, and three were absent in OMVs from 37 °C. Of the 181 proteins, 59 were differentially expressed; 30 proteins were detected with higher abundance, and 29 proteins with lower abundance at 37 °C. Among the more highly abundant proteins, significantly more proteins were predicted to be associated with virulence. These data show that temperature has an impact on the property of the OMVs, and this might affect the outcome of colonization/infection by C. jejuni in different hosts.
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