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- Carlquist, Magnus, et al.
(author)
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Physiological heterogeneities in microbial populations and implications for physical stress tolerance
- 2012
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In: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 11
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Journal article (peer-reviewed)abstract
- Background: Traditionally average values of the whole population are considered when analysing microbial cell cultivations. However, a typical microbial population in a bioreactor is heterogeneous in most phenotypes measurable at a single-cell level. There are indications that such heterogeneity may be unfavourable on the one hand (reduces yields and productivities), but also beneficial on the other hand (facilitates quick adaptation to new conditions - i.e. increases the robustness of the fermentation process). Understanding and control of microbial population heterogeneity is thus of major importance for improving microbial cell factory processes. Results: In this work, a dual reporter system was developed and applied to map growth and cell fitness heterogeneities within budding yeast populations during aerobic cultivation in well-mixed bioreactors. The reporter strain, which was based on the expression of green fluorescent protein (GFP) under the control of the ribosomal protein RPL22a promoter, made it possible to distinguish cell growth phases by the level of fluorescence intensity. Furthermore, by exploiting the strong correlation of intracellular GFP level and cell membrane integrity it was possible to distinguish subpopulations with high and low cell membrane robustness and hence ability to withstand freeze-thaw stress. A strong inverse correlation between growth and cell membrane robustness was observed, which further supports the hypothesis that cellular resources are limited and need to be distributed as a trade-off between two functions: growth and robustness. In addition, the trade-off was shown to vary within the population, and the occurrence of two distinct subpopulations shifting between these two antagonistic modes of cell operation could be distinguished. Conclusions: The reporter strain enabled mapping of population heterogeneities in growth and cell membrane robustness towards freeze-thaw stress at different phases of cell cultivation. The described reporter system is a valuable tool for understanding the effect of environmental conditions on population heterogeneity of microbial cells and thereby to understand cell responses during industrial process-like conditions. It may be applied to identify more robust subpopulations, and for developing novel strategies for strain improvement and process design for more effective bioprocessing.
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| 3. |
- Fernandes, Rita Lencastre, et al.
(author)
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Cell mass and cell cycle dynamics of an asynchronous budding yeast population: Experimental observations, flow cytometry data analysis, and multi-scale modeling
- 2013
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In: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 110:3, s. 812-826
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Journal article (peer-reviewed)abstract
- Despite traditionally regarded as identical, cells in a microbial cultivation present a distribution of phenotypic traits, forming a heterogeneous cell population. Moreover, the degree of heterogeneity is notably enhanced by changes in micro-environmental conditions. A major development in experimental single-cell studies has taken place in the last decades. It has however not been fully accompanied by similar contributions within data analysis and mathematical modeling. Indeed, literature reporting, for example, quantitative analyses of experimental single-cell observations and validation of model predictions for cell property distributions against experimental data is scarce. This study focuses on the experimental and mathematical description of the dynamics of cell size and cell cycle position distributions, of a population of Saccharomyces cerevisiae, in response to the substrate consumption observed during batch cultivation. The good agreement between the proposed multi-scale model (a population balance model [PBM] coupled to an unstructured model) and experimental data (both the overall physiology and cell size and cell cycle distributions) indicates that a mechanistic model is a suitable tool for describing the microbial population dynamics in a bioreactor. This study therefore contributes towards the understanding of the development of heterogeneous populations during microbial cultivations. More generally, it consists of a step towards a paradigm change in the study and description of cell cultivations, where average cell behaviors observed experimentally now are interpreted as a potential joint result of various co-existing single-cell behaviors, rather than a unique response common to all cells in the cultivation. Biotechnol. Bioeng. 2013; 110: 812826. (c) 2012 Wiley Periodicals, Inc.
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| 4. |
- Gad, Helge, et al.
(author)
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MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
- 2014
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In: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 508:7495, s. 215-221
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Journal article (peer-reviewed)abstract
- Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bindin the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.
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| 6. |
- Törneke, Krister, et al.
(author)
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Vägledning för kommunal VA-planering : för hållbar VA-försörjning och god vattenstatus
- 2014
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Reports (other academic/artistic)abstract
- Klimatförändringar och översvämningar, ökade miljökrav och en åldrad infrastruktur innebär ökade krav på kommunernas vatten- och avloppsverksamhet. Utanför verksamhetsområdet riskerar bristfälliga små avloppsanläggningar att sprida smittoämnen och bidra till att vattenförekomster inte uppnår god status. Kommunerna står inför stora investeringar för att nå en hållbar VAförsörjning. En strategisk och långsiktig VA-planering som omfattar både dricksvatten, spillvatten och dagvatten blir kommunens verktyg för att lyfta fram problem och prioritera åtgärder för att kostnadseffektivt möta de utmaningar som man står inför. Vägledningen är framtagen för att underlätta kommunernas planering för en trygg och hållbar VA-försörjning. Den ger konkreta råd för att komma igång och föreslår en stegvis planeringsprocess. Arbetssättet bygger på att börja med det som är tillgängligt, identifiera de strategiska frågorna och göra vägval inför den fortsatta planeringen. Vägledningen beskriver de olika stegen i planeringsprocessen och vilka styrdokument den bör omfatta. VA-planeringen bör initieras med ett tydligt uppdrag till en förvaltningsövergripande arbetsgrupp med tillräckliga resurser (steg 1). Steg 2 är att utarbeta en VA-översikt som beskriver omvärldsfaktorer, nuläge, förutsättningar och framtida behov. Steg 3 är att beskriva strategiska vägval för hantering av olika frågor, som fastställs i en VA-policy. Själva VAplanen (steg 4) tas fram utifrån VA-översikten och VA-policyn och innehåller en plan för såväl den allmänna anläggningen som för VA-försörjningen utanför verksamhetsområdet. VA-planen tillämpas sedan genom att åtgärderna förs in i kommunens löpande budgetprocess. Arbetet enligt VA-planen följs sedan upp regelbundet och planen revideras lämpligen varje mandatperiod (steg 5). En förutsättning för en lyckad VA-planering är att det finns en god kommunikation mellan politiker och tjänstemän från olika enheter inom kommunen. Det finns också ett stort värde i att samverka med länsstyrelser och grannkommuner för att utbyta erfarenheter. En väl genomförd VA-planering ger en beredskap och gör kommunen betydligt bättre rustad för att möta utmaningarna på VA-området och möjlighet att påverka utvecklingen i positiv riktning.
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| 9. |
- Barup, Kerstin, et al.
(author)
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Multi-disciplinary lidar applications
- 2010
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In: Laser Applications to Chemical, Security and Environmental Analysis, LACSEA 2010. - 2162-2701. - 9781557528803
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Conference paper (peer-reviewed)abstract
- Lidar is a powerful technique normally associated with atmospheric monitoring. However, lidar techniques, also of the laser-induced fluorescence and laser-induced breakdown spectroscopy varieties, provide many new possibilities in unconventional fields including cultural heritage and ecological applications.
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| 10. |
- Bestas, Burcu, et al.
(author)
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Splice-correcting oligonucleotides restore BTK function in X-linked agammaglobulinemia model
- 2014
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In: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 124:9, s. 4067-4081
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Journal article (peer-reviewed)abstract
- X-linked agammaglobulinemia (XLA) is an inherited immunodeficiency that results from mutations within the gene encoding Bruton's tyrosine kinase (BTK). Many XLA-associated mutations affect splicing of BTK pre-mRNA and severely impair B cell development. Here, we assessed the potential of antisense, splice-correcting oligonucleotides (SCOs) targeting mutated BTKtranscripts for treating XLA. Both the SCO structural design and chemical properties were optimized using 2'-O-methyl, locked nucleic acid, or phosphorodiamidate morpholino backbones. In order to have access to an animal model of XLA, we engineered a transgenic mouse that harbors a BAC with an authentic, mutated, splice-defective human BTK gene. BTK transgenic mice were bred onto a Btk knockout background to avoid interference of the orthologous mouse protein. Using this model, we determined that BTK-specific SCOs are able to correct aberrantly spliced BTK in B lymphocytes, including pro-B cells. Correction of BTK mRNA restored expression of functional protein, as shown both by enhanced lymphocyte survival and reestablished BTK activation upon B cell receptor stimulation. Furthermore, SCO treatment corrected splicing and restored BTK expression in primary cells from patients with XLA. Together, our data demonstrate that SCOs can restore BTK function and that BTK-targeting SCOs have potential as personalized medicine in patients with XLA.
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