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  • 1.
    Abbott, Jessica K.
    et al.
    Queen's University.
    Bensch, S.
    Lund University.
    Gosden, Thomas P.
    Lund University.
    Svensson, Erik I.
    Lund University.
    Patterns of differentiation in a colour polymorphism and in neutral markers reveal rapid genetic changes in natural damselfly populations2008Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 17, nr 6, s. 1597-1604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The existence and mode of selection operating on heritable adaptive traits can be inferred by comparing population differentiation in neutral genetic variation between populations (often using F(ST) values) with the corresponding estimates for adaptive traits. Such comparisons indicate if selection acts in a diversifying way between populations, in which case differentiation in selected traits is expected to exceed differentiation in neutral markers [F(ST )(selected) > F(ST )(neutral)], or if negative frequency-dependent selection maintains genetic polymorphisms and pulls populations towards a common stable equilibrium [F(ST) (selected) < F(ST) (neutral)]. Here, we compared F(ST) values for putatively neutral data (obtained using amplified fragment length polymorphism) with estimates of differentiation in morph frequencies in the colour-polymorphic damselfly Ischnura elegans. We found that in the first year (2000), population differentiation in morph frequencies was significantly greater than differentiation in neutral loci, while in 2002 (only 2 years and 2 generations later), population differentiation in morph frequencies had decreased to a level significantly lower than differentiation in neutral loci. Genetic drift as an explanation for population differentiation in morph frequencies could thus be rejected in both years. These results indicate that the type and/or strength of selection on morph frequencies in this system can change substantially between years. We suggest that an approach to a common equilibrium morph frequency across all populations, driven by negative frequency-dependent selection, is the cause of these temporal changes. We conclude that inferences about selection obtained by comparing F(ST) values from neutral and adaptive genetic variation are most useful when spatial and temporal data are available from several populations and time points and when such information is combined with other ecological sources of data.

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    FULLTEXT02
  • 2.
    Abd El-Gaber, Amira S.
    et al.
    Menoufia Univ, Fac Sci, Dept Chem, Shibin Al Kawm, Egypt.
    El Gendy, Abdel Nasser G.
    Natl Res Ctr, Med & Aromat Plants Res Dept, 33 El Bohouth St,PO 12622, Giza, Egypt.
    Elkhateeb, Ahmed
    Natl Res Ctr, Phytochem & Plant Systemat Dept, 33 El Bohouth St,PO 12622, Giza, Egypt.
    Saleh, Ibrahim A.
    Natl Res Ctr, Phytochem Dept, 33 El Bohouth St,PO 12622, Giza, Egypt.
    El-Seedi, Hesham
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Farmakognosi. Menoufia Univ, Fac Sci, Dept Chem, Shibin Al Kawm, Egypt;Univ Karachi, ICCBS, Karachi 75270, Pakistan.
    Microwave Extraction of Essential Oil from Anastatica hierochuntica (L): Comparison with Conventional Hydro-Distillation and Steam Distillation2018Ingår i: Journal of Essential Oil-Bearing Plants (JEOBP), ISSN 0972-060X, E-ISSN 0976-5026, Vol. 21, nr 4, s. 1003-1010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article stands to introduce microwave assisted extraction (MAE) as a more effective method for extraction of Anastatica hierochuntica (L) essential oils (EOs) compared to traditional hydrodistillation (HD) and steam distillation (SD) methods. Analysis of EOs by gas chromatography-mass spectrometry (GC/MS) showed significant differences in the constituents and percentages of the obtained oils. Using MAE and HD obtained oxygenated monoterpenes 50.79 % whereas SD obtained sesquiterpene hydrocarbons 79.84 % as major contents of the extracted oils. This is the first report of EO composition of the aerials parts of A. heirochunatica. It offered several advantages of MAE technique as a green method with shorter extraction time (60 min) and better yield.

  • 3.
    Abdalaal, Hind
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Pundir, Shreya
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi.
    Ge, Xueliang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi.
    Sanyal, Suparna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi.
    Näsvall, Joakim
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Collateral toxicity limits the evolution of bacterial Release Factor 2 towards total omnipotence2020Ingår i: Molecular biology and evolution, ISSN 0737-4038, E-ISSN 1537-1719, artikel-id 10.1093/molbev/msaa129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    When new genes evolve through modification of existing genes, there are often trade-offs between the new and original functions, making gene duplication and amplification necessary to buffer deleterious effects on the original function. We have used experimental evolution of a bacterial strain lacking peptide release factor 1 (RF1) in order to study how peptide release factor 2 (RF2) evolves to compensate the loss of RF1. As expected, amplification of the RF2-encoding gene prfB to high copy number was a rapid initial response, followed by the appearance of mutations in RF2 and other components of the translation machinery. Characterization of the evolved RF2 variants by their effects on bacterial growth rate, reporter gene expression, and in vitro translation termination reveals a complex picture of reduced discrimination between the cognate and near cognate stop codons and highlight a functional trade-off that we term “collateral toxicity”. We suggest that this type of trade-off may be a more serious obstacle in new gene evolution than the more commonly discussed evolutionary trade-offs between “old” and “new” functions of a gene, as it cannot be overcome by gene copy number changes. Further, we suggest a model for how RF2 autoregulation responds not only to alterations in the demand for RF2 activity, but also for RF1 activity.

  • 4.
    Abdel Rehim, Abbi
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Abdel Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Screening and determination of drugs in human saliva utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry2013Ingår i: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, nr 9, s. 1188-1191Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents a new method for collecting and handling saliva samples using an automated analytical microsyringe and microextraction by packed syringe (MEPS). The screening and determination of lidocaine in human saliva samples utilizing MEPS and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were carried out. An exact volume of saliva could be collected. The MEPS C-8-cartridge could be used for 50 extractions before it was discarded. The extraction recovery was about 60%. The pharmacokinetic curve of lidocaine in saliva using MEPS-LC-MS/MS is reported.

  • 5.
    Abdel-Rehim, Abbi
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Abdel-Rehim, Mohamed
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Evaluation of microextraction by packed sorbent and micro-liquid chromatography-tandem mass spectrometry as a green approach in bioanalysis2013Ingår i: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, nr 10, s. 1225-1233Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study the use of micro-liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was investigated in routine bioanalysis application for separation and quantification of pro-drug AZD6319 (developed for aldezheimer treatment). Microextraction by packed sorbent (MEPS) was used as sample clean-up method. The focus of this study was put on the evaluation of the usability of smaller column diameters such as 1.0 and 0.3mm instead of 2.1mm in bioanalysis application to reduce solvent consumption and sample volumes. Solvent consumption was reduced by 80% when a 1.0mm column was used compared with 2.1mm column. Robustness of the micro-columns in terms of accuracy and precision was investigated. The application of LC-MS/MS for the quantitative analysis of AZD6319 in plasma samples showed good selectivity, accuracy and precision. The coefficients of determination (R-2) were >0.998 for all runs using plasma samples on the studied micro-columns. The inter-day accuracy values for quality control samples ranged from 99 to 103% and from 96 to 105% for 0.3x50mm and 1.0x50mm columns, respectively. The inter-day precision values ranged from 4.0 to 9.0% and from 4.0 to 8.0% for 0.3x50 and 1.0x50mm columns, respectively. In addition the sensitivity was increased by three times using a 1.0mm column compared with 2.1mm. Furthermore, robustness of the micro-columns from different manufacturers was investigated.

  • 6.
    Abdurakhmanov, Eldar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Biokemi.
    Discovery and evaluation of direct acting antivirals against hepatitis C virus2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Until recently, the standard therapy for hepatitis C treatment has been interferon and ribavirin. Such treatment has only 50% efficacy and is not well tolerated. The emergence of new drugs has increased the treatment efficacy to 90%. Despite such an achievement, the success is limited since the virus mutates rapidly, causing the emergence of drug resistant forms. In addition, most new drugs were developed to treat genotype 1 infections. Thus, development of new potent antivirals is needed and drug discovery against hepatitis C is continued.

    In this thesis, a FRET-based protease assay was used to evaluate new pyrazinone based NS3 protease inhibitors that are structurally different to the newly approved and currently developing drugs. Several compounds in this series showed good potencies in the nanomolar range against NS3 proteases from genotype 1, 3, and the drug resistance variant R155K. We assume that these compounds can be further developed into drug candidates that possess activity against above mentioned enzyme variants.

    By using SPR technology, we analyzed interaction mechanisms and characteristics of allosteric inhibitors targeting NS5B polymerases from genotypes 1 and 3. The compounds exhibited different binding mechanisms and displayed a low affinity against NS5B from genotype 3.

    In order to evaluate the activity and inhibitors of the NS5B polymerase, we established an SPR based assay, which enables the monitoring of polymerization and its inhibition in real time. This assay can readily be implemented for the discovery of inhibitors targeting HCV.

    An SPR based fragment screening approach has also been established. A screen of a fragment library has been performed in order to identify novel scaffolds that can be used as a starting point for development of new allosteric inhibitors against NS5B polymerase. Selected fragments will be further elaborated to generate a new potent allosteric drug candidate.

    Alternative approaches have successfully been developed and implemented to the discovery of potential lead compounds targeting two important HCV drug targets.

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  • 7. Abdurakhmanov, Eldar
    et al.
    Danielson, Helena
    A time-resolved surface plasmon resonance based hepatitis C virus NS5B polymerase assay and its application for drug discoveryManuskript (preprint) (Övrigt vetenskapligt)
  • 8.
    Abdurakhmanov, Eldar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Biokemi.
    Solbak, Sara
    Danielson, Helena
    Characterization of allosteric inhibitors of hepatitis C virus polymerase – a genotype comparative studyManuskript (preprint) (Övrigt vetenskapligt)
  • 9.
    Abdurakhmanov, Eldar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Biokemi.
    Solbak, Sara Oie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Biokemi.
    Danielson, U. Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Biokemi.
    Biophysical Mode-of-Action and Selectivity Analysis of Allosteric Inhibitors of Hepatitis C Virus (HCV) Polymerase2017Ingår i: Viruses, ISSN 1999-4915, E-ISSN 1999-4915, Vol. 9, nr 6, artikel-id 151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Allosteric inhibitors of hepatitis C virus (HCV) non-structural protein 5B (NS5B) polymerase are effective for treatment of genotype 1, although their mode of action and potential to inhibit other isolates and genotypes are not well established. We have used biophysical techniques and a novel biosensor-based real-time polymerase assay to investigate the mode-of-action and selectivity of four inhibitors against enzyme from genotypes 1b (BK and Con1) and 3a. Two thumb inhibitors (lomibuvir and filibuvir) interacted with all three NS5B variants, although the affinities for the 3a enzyme were low. Of the two tested palm inhibitors (dasabuvir and nesbuvir), only dasabuvir interacted with the 1b variant, and nesbuvir interacted with NS5B 3a. Lomibuvir, filibuvir and dasabuvir stabilized the structure of the two 1b variants, but not the 3a enzyme. The thumb compounds interfered with the interaction between the enzyme and RNA and blocked the transition from initiation to elongation. The two allosteric inhibitor types have different inhibition mechanisms. Sequence and structure analysis revealed differences in the binding sites for 1b and 3a variants, explaining the poor effect against genotype 3a NS5B. The indirect mode-of-action needs to be considered when designing allosteric compounds. The current approach provides an efficient strategy for identifying and optimizing allosteric inhibitors targeting HCV genotype 3a.

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  • 10.
    Abedi-Valugerdi, Manuchehr
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Mercury and silver induce B cell activation and anti-nucleolar autoantibody production in outbred mouse stocks: are environmental factors more important than the susceptibility genes in connection with autoimmunity?2009Ingår i: Clinical and Experimental Immunology, ISSN 0009-9104, E-ISSN 1365-2249, Vol. 155, nr 1, s. 117-124Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Environmental and predisposing genetic factors are known to play a crucial role in the development of systemic autoimmune diseases. With respect to the role of environmental factors, it is not known how and to what extent they contribute to the initiation and exacerbation of systemic autoimmunity. In the present study, I considered this issue and asked if environmental factors can induce autoimmunity in the absence of specific susceptible genes. The development of genetically controlled mercury- and silver-induced B cell activation and anti-nucleolar autoantibodies (ANolA) production in genetically heterozygous outbred Institute of Cancer Research (ICR), Naval Medical Research Institute (NMRI) and Black Swiss mouse stocks were analysed. Four weeks of treatment with both mercury and silver induced a strong B cell activation characterized by increased numbers of splenic antibody-secreting cells of at least one or more immunoglobulin (Ig) isotype(s) in all treated stocks. The three stocks also exhibited a marked increase in the serum IgE levels in response to mercury, but not silver. More importantly, in response to mercury a large numbers of ICR (88%), NMRI (96%) and Black Swiss (100%) mice produced different levels of IgG1 and IgG2a ANolA (a characteristic which is linked strictly to the H-2 genes). Similarly, but at lower magnitudes, treatment with silver also induced the production of IgG1 and IgG2a ANolA in 60% of ICR, 75% of NMRI and 100% of Black Swiss mice. Thus, the findings of this study suggest that long-term exposure to certain environmental factors can activate the immune system to produce autoimmunity per se, without requiring specific susceptible genes.

  • 11. Abel, John H.
    et al.
    Drawert, Brian
    Hellander, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för beräkningsvetenskap. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Tillämpad beräkningsvetenskap.
    Petzold, Linda R.
    GillesPy: A Python package for stochastic model building and simulation2016Ingår i: IEEE Life Sciences Letters, E-ISSN 2332-7685, Vol. 2, s. 35-38Artikel i tidskrift (Refereegranskat)
  • 12.
    Abelein, Axel
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Abrahams, Jan Pieter
    Danielsson, Jens
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Gräslund, Astrid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Jarvet, Juri
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik. National Institute of Chemical Physics and Biophysics, Estonia.
    Luo, Jinghui
    Tiiman, Ann
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Wärmländer, Sebastian K. T. S.
    The hairpin conformation of the amyloid beta peptide is an important structural motif along the aggregation pathway2014Ingår i: Journal of Biological Inorganic Chemistry, ISSN 0949-8257, E-ISSN 1432-1327, Vol. 19, nr 4-5, s. 623-634Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The amyloid beta (A beta) peptides are 39-42 residue-long peptides found in the senile plaques in the brains of Alzheimer's disease (AD) patients. These peptides self-aggregate in aqueous solution, going from soluble and mainly unstructured monomers to insoluble ordered fibrils. The aggregation process(es) are strongly influenced by environmental conditions. Several lines of evidence indicate that the neurotoxic species are the intermediate oligomeric states appearing along the aggregation pathways. This minireview summarizes recent findings, mainly based on solution and solid-state NMR experiments and electron microscopy, which investigate the molecular structures and characteristics of the A beta peptides at different stages along the aggregation pathways. We conclude that a hairpin-like conformation constitutes a common motif for the A beta peptides in most of the described structures. There are certain variations in different hairpin conformations, for example regarding H-bonding partners, which could be one reason for the molecular heterogeneity observed in the aggregated systems. Interacting hairpins are the building blocks of the insoluble fibrils, again with variations in how hairpins are organized in the cross-section of the fibril, perpendicular to the fibril axis. The secondary structure propensities can be seen already in peptide monomers in solution. Unfortunately, detailed structural information about the intermediate oligomeric states is presently not available. In the review, special attention is given to metal ion interactions, particularly the binding constants and ligand structures of A beta complexes with Cu(II) and Zn(II), since these ions affect the aggregation process(es) and are considered to be involved in the molecular mechanisms underlying AD pathology.

  • 13.
    Abelein, Axel
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Bolognesi, Benedetta
    Dobson, Christopher M.
    Gräslund, Astrid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Lendel, Christofer
    Hydrophobicity and conformational change as mechanistic determinants for nonspecific modulators of amyloid β self-assembly2012Ingår i: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 51, nr 1, s. 126-137Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The link between many neurodegenerative disorders, including Alzheimer's and Parkinson's diseases, and the aberrant folding and aggregation of proteins has prompted a comprehensive search for small organic molecules that have the potential to inhibit such processes. Although many compounds have been reported to affect the formation of amyloid fibrils and/or other types of protein aggregates, the mechanisms by which they act are not well understood. A large number of compounds appear to act in a nonspecific way affecting several different amyloidogenic proteins. We describe here a detailed study of the mechanism of action of one representative compound, lacmoid, in the context of the inhibition of the aggregation of the amyloid β-peptide (Aβ) associated with Alzheimer's disease. We show that lacmoid binds Aβ(1-40) in a surfactant-like manner and counteracts the formation of all types of Aβ(1-40) and Aβ(1-42) aggregates. On the basis of these and previous findings, we are able to rationalize the molecular mechanisms of action of nonspecific modulators of protein self-assembly in terms of hydrophobic attraction and the conformational preferences of the polypeptide.

  • 14.
    Abelein, Axel
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Kaspersen, Jørn Døvling
    Nielsen, Søren Bang
    Jensen, Grethe Vestergaard
    Christiansen, Gunna
    Pedersen, Jan Skov
    Danielsson, Jens
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Otzen, Daniel E.
    Gräslund, Astrid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Formation of dynamic soluble surfactant-induced amyloid β peptide aggregation intermediates2013Ingår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 288, nr 32, s. 23518-23528Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Intermediate amyloidogenic states along the amyloid β peptide (Aβ) aggregation pathway have been shown to be linked to neurotoxicity. To shed more light on the different structures that may arise during Aβ aggregation, we here investigate surfactant-induced Aβ aggregation. This process leads to co-aggregates featuring a β-structure motif that is characteristic for mature amyloid-like structures. Surfactants induce secondary structure in Aβ in a concentration-dependent manner, from predominantly random coil at low surfactant concentration, via β-structure to the fully formed α-helical state at high surfactant concentration. The β-rich state is the most aggregation-prone as monitored by thioflavin T fluorescence. Small angle x-ray scattering reveals initial globular structures of surfactant-Aβ co-aggregated oligomers and formation of elongated fibrils during a slow aggregation process. Alongside this slow (minutes to hours time scale) fibrillation process, much faster dynamic exchange (k(ex) ∼1100 s(-1)) takes place between free and co-aggregate-bound peptide. The two hydrophobic segments of the peptide are directly involved in the chemical exchange and interact with the hydrophobic part of the co-aggregates. Our findings suggest a model for surfactant-induced aggregation where free peptide and surfactant initially co-aggregate to dynamic globular oligomers and eventually form elongated fibrils. When interacting with β-structure promoting substances, such as surfactants, Aβ is kinetically driven toward an aggregation-prone state.

  • 15.
    Abelein, Axel
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Lang, Lisa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Lendel, Christofer
    Gräslund, Astrid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Danielsson, Jens
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Transient small molecule interactions kinetically modulate amyloid beta peptide self-assembly2012Ingår i: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 586, nr 22, s. 3991-3995Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Small organic molecules, like Congo red and lacmoid, have been shown to modulate the self-assembly of the amyloid beta peptide (A beta). Here, we show that A beta forms NMR invisible non-toxic co-aggregates together with lacmoid as well as Congo red. We find that the interaction involves two distinct kinetic processes and at every given time point only a small fraction of A beta is in the co-aggregate. These weak transient interactions kinetically redirect the aggregation prone A beta from self-assembling into amyloid fibrils. These findings suggest that even such weak binders might be effective as therapeutics against pathogenic protein aggregation.

  • 16.
    Abellan-Flos, Marta
    et al.
    Univ Namur, Belgium;PSL Univ, France.
    Timmer, Brian J. J.
    KTH Royal Instute of Technology, Sweden.
    Altun, Samuel
    Attana AB, Sweden.
    Aastrup, Teodor
    Attana AB, Sweden.
    Vincent, Stephane P.
    Univ Namur, Belgium.
    Ramström, Olof
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för kemi och biomedicin (KOB). KTH Royal Instute of Technology, Sweden;Univ Massachusetts, USA.
    QCM sensing of multivalent interactions between lectins and well-defined glycosylated nanoplatforms2019Ingår i: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 139, artikel-id 111328Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quartz crystal microbalance (QCM) methodology has been adopted to unravel important factors contributing to the "cluster glycoside effect" observed in carbohydrate-lectin interactions. Well-defined, glycosylated nanostructures of precise sizes, geometries and functionalization patterns were designed and synthesized, and applied to analysis of the interaction kinetics and thermodynamics with immobilized lectins. The nanostructures were based on Borromean rings, dodecaamine cages, and fullerenes, each of which carrying a defined number of carbohydrate ligands at precise locations. The synthesis of the Borromeates and dodecaamine cages was easily adjustable due to the modular assembly of the structures, resulting in variations in presentation mode. The binding properties of the glycosylated nanoplatforms were evaluated using flow-through QCM technology, as well as hemagglutination inhibition assays, and compared with dodecaglycosylated fullerenes and a monovalent reference. With the QCM setup, the association and dissociation rate constants and the associated equilibrium constants of the interactions could be estimated, and the results used to delineate the multivalency effects of the lectin-nanostructure interactions.

  • 17.
    Aboye, Teshome L.
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för farmakognosi.
    Strömstedt, Adam A.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för farmakognosi.
    Gunasekera, Sunithi
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för farmakognosi.
    Bruhn, Jan G.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för farmakognosi.
    El-Seedi, Hesham
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för farmakognosi.
    Rosengren, K. Johan
    Göransson, Ulf
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för farmakognosi.
    A Cactus-Derived Toxin-Like Cystine Knot Peptide with Selective Antimicrobial Activity2015Ingår i: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 16, nr 7, s. 1068-1077Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Naturally occurring cystine knot peptides show a wide range of biological activity, and as they have inherent stability they represent potential scaffolds for peptide-based drug design and biomolecular engineering. Here we report the discovery, sequencing, chemical synthesis, three-dimensional solution structure determination and bioactivity of the first cystine knot peptide from Cactaceae (cactus) family: Ep-AMP1 from Echinopsis pachanoi. The structure of Ep-AMP1 (35 amino acids) conforms to that of the inhibitor cystine knot (or knottin) family but represents a novel diverse sequence; its activity was more than 500 times higher against bacterial than against eukaryotic cells. Rapid bactericidal action and liposome leakage implicate membrane permeabilisation as the mechanism of action. Sequence homology places Ec-AMP1 in the plant C6-type of antimicrobial peptides, but the three dimensional structure is highly similar to that of a spider neurotoxin.

  • 18. Abraham, Edit
    et al.
    Miskolczi, Pal
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Ayaydin, Ferhan
    Yu, Ping
    Kotogany, Edit
    Bako, Laszlo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Oetvoes, Krisztina
    Horvath, Gabor V.
    Dudits, Denes
    Immunodetection of retinoblastoma-related protein and its phosphorylated form in interphase and mitotic alfalfa cells2011Ingår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 62, nr 6, s. 2155-2168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plant retinoblastoma-related (RBR) proteins are primarily considered as key regulators of G(1)/S phase transition, with functional roles in a variety of cellular events during plant growth and organ development. Polyclonal antibody against the C-terminal region of the Arabidopsis RBR1 protein also specifically recognizes the alfalfa 115 kDa MsRBR protein, as shown by the antigen competition assay. The MsRBR protein was detected in all cell cycle phases, with a moderate increase in samples representing G(2)/M cells. Antibody against the human phospho-pRb peptide (Ser807/811) cross-reacted with the same 115 kDa MsRBR protein and with the in vitro phosphorylated MsRBR protein C-terminal fragment. Phospho-MsRBR protein was low in G(1) cells. Its amount increased upon entry into the S phase and remained high during the G(2)/M phases. Roscovitine treatment abolished the activity of alfalfa MsCDKA1;1 and MsCDKB2;1, and the phospho-MsRBR protein level was significantly decreased in the treated cells. Colchicine block increased the detected levels of both forms of MsRBR protein. Reduced levels of the MsRBR protein in cells at stationary phase or grown in hormone-free medium can be a sign of the division-dependent presence of plant RBR proteins. Immunolocalization of the phospho-MsRBR protein indicated spots of variable number and size in the labelled interphase nuclei and high signal intensity of nuclear granules in prophase. Structures similar to phospho-MsRBR proteins cannot be recognized in later mitotic phases. Based on the presented western blot and immunolocalization data, the possible involvement of RBR proteins in G(2)/M phase regulation in plant cells is discussed.

  • 19.
    Abramson, Jeff
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Structural studies on the integral membrane protein, ubiquinol oxidase from Escherichia coli2001Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Heme-copper oxidases are redox-driven proton pumps that couple the reduction of molecular oxygen to water with the vectorial translocation of protons across the membrane. The proton gradient generated by heme-copper oxidases and the other members of the aerobic respiratory chain is ultimately used to drive the synthesis of ATP. There are two main branches of the heme-copper oxidases that are characterized by the electron donating substrate; the cytochrome c oxidases, which use cytochrome c as the electron donor, and the ubiquinol oxidases, which use a lipid-soluble molecule, ubiquinol, as their electron donor. These enzymes share important structural and functional features.

    This thesis presents the procedures that have led to the first crystal structure of a ubiquinol oxidase, cytochrome bo, oxidase from Escherichia coli, at a resolution of 3.5 Å. The overall structure of the enzyme is similar to those of cytochrome c oxidases; however the membrane spanning region of subunit I contains a cluster of polar residues exposed to the interior of the lipid bilayer. No such structural feature is present in cytochrome c oxidases. Mutagenesis studies on residues in this region strongly suggest that this area forms a ubiquinone binding site. A comparison of this region with known ubiquinone binding sites shows remarkable similarities. In light of these findings specific roles for these polar residues is proposed in electron and proton transfer in ubiquinol oxidase.

    A fusion protein of cytochrome bo3-Protein Z was generated in an attempt to increase the hydrophilic surface of the protein, thus extending protein-protein contacts within the crystal lattice structure. Such an approach can be used to facilitate crystallization.

  • 20.
    Abreu-Vieira, Gustavo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut. National Institute of Diabetes and Digestive and Kidney Diseases, NIH, USA.
    Xiao, Cuiying
    Gavrilova, Oksana
    Reitman, Marc L.
    Integration of body temperature into the analysis of energy expenditure in the mouse2015Ingår i: Molecular Metabolism, ISSN 2212-8778, Vol. 4, nr 6, s. 461-470Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives: We quantified the effect of environmental temperature on mouse energy homeostasis and body temperature.Methods: The effect of environmental temperature (4e33 C) on body temperature, energy expenditure, physical activity, and food intake invarious mice (chow diet, high-fat diet, Brs3-/y, lipodystrophic) was measured using continuous monitoring.Results: Body temperature depended most on circadian phase and physical activity, but also on environmental temperature. The amounts ofenergy expenditure due to basal metabolic rate (calculated via a novel method), thermic effect of food, physical activity, and cold-inducedthermogenesis were determined as a function of environmental temperature. The measured resting defended body temperature matchedthat calculated from the energy expenditure using Fourier’s law of heat conduction. Mice defended a higher body temperature during physicalactivity. The cost of the warmer body temperature during the active phase is 4e16% of total daily energy expenditure. Parameters measured indiet-induced obese and Brs3-/y mice were similar to controls. The high post-mortem heat conductance demonstrates that most insulation in miceis via physiological mechanisms.Conclusions: At 22 C, cold-induced thermogenesis isw120% of basal metabolic rate. The higher body temperature during physical activity isdue to a higher set point, not simply increased heat generation during exercise. Most insulation in mice is via physiological mechanisms, with littlefrom fur or fat. Our analysis suggests that the definition of the upper limit of the thermoneutral zone should be re-considered. Measuring bodytemperature informs interpretation of energy expenditure data and improves the predictiveness and utility of the mouse to model human energyhomeostasis.

  • 21. Adase, Christopher A.
    et al.
    Draheim, Roger R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik. Goethe University .
    Rueda, Garrett
    Desai, Raj
    Manson, Michael D.
    Residues at the Cytoplasmic End of Transmembrane Helix 2 Determine the Signal Output of the Tar(Ec) Chemoreceptor2013Ingår i: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 52, nr 16, s. 2729-2738Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Baseline signal output and communication between the periplasmic and cytoplasmic domains of the Escherichia colt aspartate chemoreceptor Tar(Ec) are both strongly influenced by residues at the C-terminus of transmembrane helix 2 (TM2). In particular, the cytoplasmic aromatic anchor, composed of residues Trp-209 and Tyr-210 in wild type Tar(Ec) is important for determining the CheA kinase-stimulating activity of the receptor and its ability to respond to chemoeffector-induced stimuli. Here, we have studied the effect on Tar(Ec) function of the six residue sequence at positions 207-212 Moving various combinations of aromatic residues among these positions generates substantial changes M receptor activity. Trp has the largest effect on function, both in maintaining normal activity and in altering activity when it is moved. Tyr has a weaker effect, and Phe has the weakest; however, all three aromatic residues can alter signal output when they are placed in novel positions. We also find that Gly-211 plays an important role in receptor function, perhaps because of the flexibility it introduces into the TM2-HAMP domain connector. The conservation of this Gly residue in the high-abundance chemoreceptors of E. coli and Salmonella enterica suggests that it may be important for the nuanced, bidirectional transmembrane signaling that occurs in these proteins.

  • 22.
    Adhikari, Deepak
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Signaling pathways in the development of female germ cells2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Primordial follicles are the first small follicles to appear in the mammalian ovary. Women are born with a fixed number of primordial follicles in the ovaries. Once formed, the pool of primordial follicles serves as a source of developing follicles and oocytes. The first aim of this thesis was to investigate the functional role of the intra-oocyte signaling pathways, especially the phosphatidylinositol-3 kinase (PI3K) and mammalian target of rapamycin complex 1 (mTORC1) pathways in the regulation of primordial follicle activation and survival. We found that a primordial follicle remains dormant when the PI3K and mTORC1 signaling in its oocyte is activated to an appropriate level, which is just sufficient to maintain its survival, but not sufficient for its growth initiation. Hyperactivation of either of these signaling pathways causes global activation of the entire pool of primordial follicles leading to the exhaustion of all the follicles in young adulthood in mice. Mammalian oocytes, while growing within the follicles, remain arrested at prophase I of meiosis. Oocytes within the fully-grown antral follicles resume meiosis upon a preovulatory surge of leutinizing hormone (LH), which indicates that LH mediates the resumption of meiosis. The prophase I arrest in the follicle-enclosed oocyte is the result of low maturation promoting factor (MPF) activity, and resumption of meiosis upon the arrival of hormonal signals is mediated by activation of MPF. MPF is a complex of cyclin dependent kinase 1 (Cdk1) and cyclin B1, which is essential and sufficient for entry into mitosis. Although much of the mitotic cell cycle machinery is shared during meiosis, lack of Cdk2  in mice leads to a postnatal loss of all oocytes, indicating that Cdk2 is important for oocyte survival, and probably oocyte meiosis also. There have been conflicting results earlier about the role of Cdk2 in metaphase II arrest of Xenopus  oocytes. Thus the second aim of the thesis was to identify the specific Cdk that is essential for mouse oocyte meiotic maturation. We generated mouse models with oocytespecific deletion of Cdk1  or Cdk2  and studied the specific requirements of Cdk1 and Cdk2 during resumption of oocyte meiosis. We found that only Cdk1 is essential and sufficient for the oocyte meiotic maturation. Cdk1 does not only phosphorylate the meiotic phosphoproteins during meiosis resumption but also phosphorylates and suppresses the downstream protein phosphatase 1, which is essential for protecting the Cdk1 substrates from dephosphorylation.

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    Thesis-Deepak Adhikari
  • 23.
    Adler, Marlen
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Mechanisms and Dynamics of Carbapenem Resistance in Escherichia coli2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The emergence of extended spectrum β-lactamase (ESBL) producing Enterobacteriaceae worldwide has led to an increased use of carbapenems and may drive the development of carbapenem resistance. Existing mechanisms are mainly due to acquired carbapenemases or the combination of ESBL-production and reduced outer membrane permeability. The focus of this thesis was to study the development of carbapenem resistance in Escherichia coli in the presence and absence of acquired β-lactamases. To this end we used the resistance plasmid pUUH239.2 that caused the first major outbreak of ESBL-producing Enterobacteriaceae in Scandinavia.

    Spontaneous carbapenem resistance was strongly favoured by the presence of the ESBL-encoding plasmid and different mutational spectra and resistance levels arose for different carbapenems. Mainly, loss of function mutations in the regulators of porin expression caused reduced influx of antibiotic into the cell and in combination with amplification of β-lactamase genes on the plasmid this led to high resistance levels. We further used a pharmacokinetic model, mimicking antibiotic concentrations found in patients during treatment, to test whether ertapenem resistant populations could be selected even at these concentrations. We found that resistant mutants only arose for the ESBL-producing strain and that an increased dosage of ertapenem could not prevent selection of these resistant subpopulations. In another study we saw that carbapenem resistance can even develop in the absence of ESBL-production. We found mutants in export pumps and the antibiotic targets to give high level resistance albeit with high fitness costs in the absence of antibiotics. In the last study, we used selective amplification of β-lactamases on the pUUH239.2 plasmid by carbapenems to determine the cost and stability of gene amplifications. Using mathematical modelling we determined the likelihood of evolution of new gene functions in this region. The high cost and instability of the amplified state makes de novo evolution very improbable, but constant selection of the amplified state may balance these factors until rare mutations can establish a new function.

    In my studies I observed the influence of β-lactamases on carbapenem resistance and saw that amplification of these genes would further contribute to resistance. The rapid disappearance of amplified arrays of resistance genes in the absence of antibiotic selection may lead to the underestimation of gene amplification as clinical resistance mechanism. Amplification of β-lactamase genes is an important stepping-stone and might lead to the evolution of new resistance genes.

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  • 24.
    Adler, Marlen
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Anjum, Mehreen
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Andersson, Dan I.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Sandegren, Linus
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Combinations of mutations in envZ, ftsI, mrdA, acrB and acrR can cause high-level carbapenem resistance in Escherichia coli2016Ingår i: Journal of Antimicrobial Chemotherapy, ISSN 0305-7453, E-ISSN 1460-2091, Vol. 71, nr 5, s. 1188-1198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The worldwide spread of ESBL-producing Enterobacteriaceae has led to an increased use of carbapenems, the group of beta-lactams with the broadest spectrum of activity. Bacterial resistance to carbapenems is mainly due to acquired carbapenemases or a combination of ESBL production and reduced drug influx via loss of outer-membrane porins. Here, we have studied the development of carbapenem resistance in Escherichia coli in the absence of beta-lactamases. We selected mutants with high-level carbapenem resistance through repeated serial passage in the presence of increasing concentrations of meropenem or ertapenem for similar to 60 generations. Isolated clones were whole-genome sequenced, and the order in which the identified mutations arose was determined in the passaged populations. Key mutations were reconstructed, and bacterial growth rates of populations and isolated clones and resistance levels to 23 antibiotics were measured. High-level resistance to carbapenems resulted from a combination of downstream effects of envZ mutation and target mutations in AcrAB-TolC-mediated drug export, together with PBP genes [mrdA (PBP2) after meropenem exposure or ftsI (PBP3) after ertapenem exposure]. Our results show that antibiotic resistance evolution can occur via several parallel pathways and that new mechanisms may appear after the most common pathways (i.e. beta-lactamases and loss of porins) have been eliminated. These findings suggest that strategies to target the most commonly observed resistance mechanisms might be hampered by the appearance of previously unknown parallel pathways to resistance.

  • 25.
    Adler, Marlen
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Anjum, Mehreen
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Berg, Otto, G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Beräknings- och systembiologi.
    Andersson, Dan I.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Sandegren, Linus
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    High Fitness Costs and Instability of Gene Duplications Reduce Rates of Evolution of New Genes by Duplication-Divergence Mechanisms2014Ingår i: Molecular biology and evolution, ISSN 0737-4038, E-ISSN 1537-1719, Vol. 31, nr 6, s. 1526-1535Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    An important mechanism for generation of new genes is by duplication-divergence of existing genes. Duplication-divergence includes several different sub-models, such as subfunctionalization where after accumulation of neutral mutations the original function is distributed between two partially functional and complementary genes, and neofunctionalization where a new function evolves in one of the duplicated copies while the old function is maintained in another copy. The likelihood of these mechanisms depends on the longevity of the duplicated state, which in turn depends on the fitness cost and genetic stability of the duplications. Here, we determined the fitness cost and stability of defined gene duplications/amplifications on a low copy number plasmid. Our experimental results show that the costs of carrying extra gene copies are substantial and that each additional kbp of DNA reduces fitness by approximately 0.15%. Furthermore, gene amplifications are highly unstable and rapidly segregate to lower copy numbers in absence of selection. Mathematical modelling shows that the fitness costs and instability strongly reduces the likelihood of both sub- and neofunctionalization, but that these effects can be off-set by positive selection for novel beneficial functions.

  • 26.
    Adlerz, Linda
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi.
    Holback, Sofia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi.
    Multhaup, Gerd
    Iverfeldt, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi.
    IGF-1-induced Processing of the Amyloid Precursor Protein Family Is Mediated by Different Signaling Pathways2007Ingår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 282, nr 14, s. 10203-10209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mammalian amyloid precursor protein (APP) protein family consists of the APP and the amyloid precursor-like proteins 1 and 2 (APLP1 and APLP2). The neurotoxic amyloid beta-peptide (Abeta) originates from APP, which is the only member of this protein family implicated in Alzheimer disease. However, the three homologous proteins have been proposed to be processed in similar ways and to have essential and overlapping functions. Therefore, it is also important to take into account the effects on the processing and function of the APP-like proteins in the development of therapeutic drugs aimed at decreasing the production of Abeta. Insulin and insulin-like growth factor-1 (IGF-1) have been shown to regulate APP processing and the levels of Abeta in the brain. In the present study, we show that IGF-1 increases alpha-secretase processing of endogenous APP and also increases ectodomain shedding of APLP1 and APLP2 in human SH-SY5Y neuroblastoma cells. We also investigated the role of different IGF-1-induced signaling pathways, using specific inhibitors for phosphatidylinositol 3-kinase and mitogen-activated protein kinase (MAPK). Our results indicate that phosphatidylinositol 3-kinase is involved in ectodomain shedding of APP and APLP1, but not APLP2, and that MAPK is involved only in the ectodomain shedding of APLP1.

  • 27.
    Afshari Kashanian, Elisa
    Uppsala universitet, Medicinska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Detection of celery (Apium graveolens) in food with Real-Time PCR2006Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [en]

    Directive EC 2003/89/EC of the European Parliament and of the Council states that certain

    ingredients and products derived there of known to cause allergen reactions must always be

    declared. Furthermore labelling is mandatory irrespective of the amount included. The National

    Food Administration therefore needs methods for monitoring the presence of allergens in food.

    Methods already exist for most of the allergens on the EU-list, but an operational method for

    celery (Apium graveolens) is missing.

    A specific DNA-method was developed, based on TaqMan Real-Time PCR with the celery

    mannitol dehydrogenase gene as target sequence. The analysis was started with homogenisation

    of the sample followed by extraction of DNA. The Real-Time PCR method was shown to be

    specific for celery, producing a 113 bp fragment with two celery varieties and negative results

    with other closely selected species commonly present together with celery in food products (12

    samples). The detection limit was 2-20 pg DNA, which corresponds to 1-7 haploid genome

    copies. When evaluated with model samples of celery in meat, a detection limit of less than

    0,01 % was determined. When used to analyse food products from the market, six out of seven

    products declared to contain celery were correctly identified as positive.

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    FULLTEXT01
  • 28.
    Aggarwal, Tanya
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Patil, Sourabh
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Eriksson, Mikaela
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Hayder, Maher
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Fredriksson, Robert
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Knockdown of SLC38 Transporter Ortholog-CG13743 Reveals a Metabolic Relevance in Drosophila2020Ingår i: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 10, artikel-id 1592Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Solute Carrier (SLC) is a cluster of families of membrane bound transporters, of which many members lack defined substrate profile, and many more are poorly characterized. Many play a vital role in regulating metabolic systems, protein synthesis, and post translational modifications. SLC38 is one of the families of SLCs, which are also known as sodium-coupled neutral amino acid transporters (SNATs). In mice, it has 11 members (SNAT1-11) but in Drosophila there are two homologs for the SLC38 family; CG13743 and CG30394. Here, we show characteristics of Drosophila CG13743 which closely resembles SLC38A11 in humans. SLC38A11 still remains an orphan member of the SLC38 family which has not been functionally well studied. We used the UAS-GAL4 system to investigate and control gene expression using RNAi lines for ubiquitous knockdown of the CG13743 gene. It was found to be expressed mainly in salivary gland and brain. Knockdown flies had reduced body weight and consumed less sugar compared with controls. The gene knockdown also affected stored energy pools (lipids and glycogen) and influenced feeding pattern and total activity. In all, this shows novel findings for the characterization of CG13743 in Drosophila and a possible role in maintaining general metabolic pathways and behavior of the fly.

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    fulltext
  • 29. Agnarsdottir, Margret
    et al.
    Sooman, Linda
    Bolander, Asa
    Stromberg, Sara
    Rexhepaj, Elton
    Bergqvist, Michael
    Ponten, Fredrik
    Gallagher, William
    Lennartsson, Johan
    Ekman, Simon
    Uhlen, Mathias
    KTH, Skolan för bioteknologi (BIO), Proteomik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Hedstrand, Hakan
    SOX10 expression in superficial spreading and nodular malignant melanomas2010Ingår i: Melanoma research, ISSN 0960-8931, E-ISSN 1473-5636, Vol. 20, nr 6, s. 468-478Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    SOX10 is a transcription factor expressed in nerve cells and melanocytes. The aim of this study was to investigate the protein expression pattern of SOX10 in malignant melanoma tumors and to analyze whether the results correlated with clinical parameters and the proliferation marker Ki-67. Furthermore, proliferation and migration were analyzed in three different cell lines employing SOX10 small interfering RNA-mediated silencing. Expression patterns were determined in 106 primary tumors and 39 metastases in addition to 16 normal skin samples and six benign nevi employing immunohistochemistry and tissue microarrays. The immunohistochemical staining was evaluated manually and with an automated algorithm. SOX10 was strongly expressed in the benign tissues, but for the malignant tumors superficial spreading melanomas stained stronger than nodular malignant melanomas (P = 0.008). The staining intensity was also inversely correlated with T-stage (Spearman's rho = -0.261, P = 0.008). Overall survival and time to recurrence were significantly correlated with SOX10 intensity, but not in multivariate analysis including T-stage. With the automated algorithm there was an inverse correlation between the SOX10 staining intensity and the proliferation marker, Ki-67 (rho = -0.173, P = 0.02) and a significant difference in the intensity signal between the benign tissues, the primary tumors and the metastases where the metastases stained the weakest (P <= 0.001). SOX10 downregulation resulted in variable effects on proliferation and migration rates in the melanoma cell lines. In conclusion, the SOX10 intensity level differed depending on the tissue studied and SOX10 might have a role in survival. No conclusion regarding the role of SOX10 for in-vitro proliferation and migration could be drawn. Melanoma Res 20:468-478

  • 30. Agostinho, Ana
    et al.
    Manneberg, Otto
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    van Schendel, Robin
    Hernandez-Hernandez, Abrahan
    Kouznetsova, Anna
    Blom, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Brismar, Hjalmar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Höög, Christer
    High density of REC8 constrains sister chromatid axes and prevents illegitimate synaptonemal complex formation2016Ingår i: EMBO Reports, ISSN 1469-221X, E-ISSN 1469-3178, Vol. 17, nr 6, s. 901-913Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During meiosis, cohesin complexes mediate sister chromatid cohesion (SCC), synaptonemal complex (SC) assembly and synapsis. Here, using super-resolution microscopy, we imaged sister chromatid axes in mouse meiocytes that have normal or reduced levels of cohesin complexes, assessing the relationship between localization of cohesin complexes, SCC and SC formation. We show that REC8 foci are separated from each other by a distance smaller than 15% of the total chromosome axis length in wild-type meiocytes. Reduced levels of cohesin complexes result in a local separation of sister chromatid axial elements (LSAEs), as well as illegitimate SC formation at these sites. REC8 but not RAD21 or RAD21L cohesin complexes flank sites of LSAEs, whereas RAD21 and RAD21L appear predominantly along the separated sister-chromatid axes. Based on these observations and a quantitative distribution analysis of REC8 along sister chromatid axes, we propose that the high density of randomly distributed REC8 cohesin complexes promotes SCC and prevents illegitimate SC formation.

  • 31.
    Aguilar, Ximena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Folding and interaction studies of subunits in protein complexes2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Proteins function as worker molecules in the cell and their natural environment is crowded. How they fold in a cell-like environment and how they recognize their interacting partners in such conditions, are questions that underlie the work of this thesis.

    Two distinct subjects were investigated using a combination of biochemical- and biophysical methods. First, the unfolding/dissociation of a heptameric protein (cpn10) in the presence of the crowding agent Ficoll 70. Ficoll 70 was used to mimic the crowded environment in the cell and it has been used previously to study macromolecular crowding effects, or excluded volume effects, in protein folding studies. Second, the conformational changes upon interaction between the Mediator subunit Med25 and the transcription factor Dreb2a from Arabidopsis thaliana. Mediator is a transcriptional co-regulator complex which is conserved from yeast to humans. The molecular mechanisms of its action are however not entirely understood. It has been proposed that the Mediator complex conveys regulatory signals from promoter-bound transcription factors (activators/repressors) to the RNA polymerase II machinery through conformational rearrangements.

    The results from the folding study showed that cpn10 was stabilized in the presence of Ficoll 70 during thermal- and chemical induced unfolding (GuHCl). The thermal transition midpoint increased by 4°C, and the chemical midpoint by 0.5 M GuHCl as compared to buffer conditions. Also the heptamer-monomer dissociation was affected in the presence of Ficoll 70, the transition midpoint was lower in Ficoll 70 (3.1 μM) compared to in buffer (8.1 μM) thus indicating tighter binding in crowded conditions. The coupled unfolding/dissociation free energy for the heptamer increased by about 36 kJ/mol in Ficoll. Altogether, the results revealed that the stability effect on cpn10 due to macromolecular crowding was larger in the individual monomers (33%) than at the monomer-monomer interfaces (8%).

    The results from the interaction study indicated conformational changes upon interaction between the A. thaliana Med25 ACtivator Interaction Domain (ACID) and Dreb2a. Structural changes were probed to originate from unstructured Dreb2a and not from the Med25-ACID. Human Med25-ACID was also found to interact with the plant-specific Dreb2a, even though the ACIDs from human and A. thaliana share low sequence homology. Moreover, the human Med25-interacting transcription factor VP16 was found to interact with A. thaliana Med25. Finally, NMR, ITC and pull-down experiments showed that the unrelated transcription factors Dreb2a and

    VP16 interact with overlapping regions in the ACIDs of A. thaliana and human Med25.

    The results presented in this thesis contribute to previous reports in two different aspects. Firstly, they lend support to the findings that the intracellular environment affects the biophysical properties of proteins. It will therefore be important to continue comparing results between in vitro and cell-like conditions to measure the magnitude of such effects and to improve the understanding of protein folding and thereby misfolding of proteins in cells. Better knowledge of protein misfolding mechanisms is critical since they are associated to several neurodegenerative diseases such as Alzheimer’s and Parkinson's. Secondly, our results substantiate the notion that transcription factors are able to bind multiple targets and that they gain structure upon binding. They also show that subunits of the conserved Mediator complex, despite low sequence homologies, retain a conserved structure and function when comparing evolutionary diverged species.

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  • 32.
    Aguilar, Ximena
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Blomberg, Jeanette
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Olofsson, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Schleucher, Jurgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Björklund, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Interaction Studies of the Human and Arabidopsis thaliana Med25-ACID Proteins with the Herpes Simplex Virus VP16-and Plant-Specific Dreb2a Transcription Factors2014Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 5, s. e98575-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mediator is an evolutionary conserved multi-protein complex present in all eukaryotes. It functions as a transcriptional coregulator by conveying signals from activators and repressors to the RNA polymerase II transcription machinery. The Arabidopsis thaliana Med25 (aMed25) ACtivation Interaction Domain (ACID) interacts with the Dreb2a activator which is involved in plant stress response pathways, while Human Med25-ACID (hMed25) interacts with the herpes simplex virus VP16 activator. Despite low sequence similarity, hMed25-ACID also interacts with the plant-specific Dreb2a transcriptional activator protein. We have used GST pull-down-, surface plasmon resonance-, isothermal titration calorimetry and NMR chemical shift experiments to characterize interactions between Dreb2a and VP16, with the hMed25 and aMed25-ACIDs. We found that VP16 interacts with aMed25-ACID with similar affinity as with hMed25-ACID and that the binding surface on aMed25-ACID overlaps with the binding site for Dreb2a. We also show that the Dreb2a interaction region in hMed25-ACID overlaps with the earlier reported VP16 binding site. In addition, we show that hMed25-ACID/Dreb2a and aMed25-ACID/Dreb2a display similar binding affinities but different binding energetics. Our results therefore indicate that interaction between transcriptional regulators and their target proteins in Mediator are less dependent on the primary sequences in the interaction domains but that these domains fold into similar structures upon interaction.

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  • 33.
    Aguilar-Calvo, Patricia
    et al.
    University of Calif San Diego, CA 92093 USA; University of Calif San Diego, CA 92093 USA.
    Xiao, Xiangzhu
    Case Western Reserve University, OH 44116 USA.
    Bett, Cyrus
    University of Calif San Diego, CA 92093 USA; University of Calif San Diego, CA 92093 USA; US FDA, MD USA.
    Erana, Hasier
    CIC bioGUNE, Spain.
    Soldau, Katrin
    University of Calif San Diego, CA 92093 USA.
    Castilla, Joaquin
    University of Calif San Diego, CA 92093 USA; CIC bioGUNE, Spain; Ikerbasque, Spain.
    Nilsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Surewicz, Witold K.
    Case Western Reserve University, OH 44116 USA.
    Sigurdson, Christina J.
    University of Calif San Diego, CA 92093 USA; University of Calif San Diego, CA 92093 USA; University of Calif Davis, CA 95616 USA.
    Post-translational modifications in PrP expand the conformational diversity of prions in vivo2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 43295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Misfolded prion protein aggregates (PrPSc) show remarkable structural diversity and are associated with highly variable disease phenotypes. Similarly, other proteins, including amyloid-beta, tau, alpha-synuclein, and serum amyloid A, misfold into distinct conformers linked to different clinical diseases through poorly understood mechanisms. Here we use mice expressing glycophosphatidylinositol (GPI)anchorless prion protein, PrPC, together with hydrogen-deuterium exchange coupled with mass spectrometry (HXMS) and a battery of biochemical and biophysical tools to investigate how posttranslational modifications impact the aggregated prion protein properties and disease phenotype. Four GPI-anchorless prion strains caused a nearly identical clinical and pathological disease phenotype, yet maintained their structural diversity in the anchorless state. HXMS studies revealed that GPIanchorless PrPSc is characterized by substantially higher protection against hydrogen/deuterium exchange in the C-terminal region near the N-glycan sites, suggesting this region had become more ordered in the anchorless state. For one strain, passage of GPI-anchorless prions into wild type mice led to the emergence of a novel strain with a unique biochemical and phenotypic signature. For the new strain, histidine hydrogen-deuterium mass spectrometry revealed altered packing arrangements of beta-sheets that encompass residues 139 and 186 of PrPSc. These findings show how variation in posttranslational modifications may explain the emergence of new protein conformations in vivo and also provide a basis for understanding how the misfolded protein structure impacts the disease.

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  • 34. Ahad, Abdul
    et al.
    Keech, Olivier
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Sjödin, Andreas
    Lindén, Pernilla
    Brouwer, Bastiaan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Stenlund, Hans
    Moritz, Thomas
    Jansson, Stefan
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Comparison between leaves from darkened plants and individually-darkened leaves reveals differential metabolic strategies in response to darknessManuskript (preprint) (Övrigt vetenskapligt)
  • 35.
    Ahlman, B.
    et al.
    Department of Surgery, Karolinska Hospital, Metabolic Research Laboratory, St Göran's Hospital, Stockholm, Sweden.
    Ljungqvist, Olle
    Department of Surgery, Karolinska Hospital, Stockholm, Sweden.
    Persson, B.
    cDepartment of Radiology, Karolinska Hospital, Stockholm, Sweden.
    Bindslev, L.
    Department of Anesthesiology and Intensive Care, Karolinska Hospital, Department of Anesthesiology and Intensive Care, St Göran's Hospital, Stockholm, Sweden.
    Wernerman, J.
    Metabolic Research Laboratory, St Göran's Hospital, Stockholm, Sweden.
    Intestinal amino acid content in critically ill patients1995Ingår i: JPEN - Journal of Parenteral and Enteral Nutrition, ISSN 0148-6071, E-ISSN 1941-2444, Vol. 19, nr 4, s. 272-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: The purpose of the study was to determine the concentrations of free amino acids and the total protein content of the human intestinal mucosa during critical illness. Methods: The free amino acid and protein concentrations in endoscopically obtained biopsy specimens from the duodenum and the distal colonic segments were determined on 19 critically ill patients. The free amino acids were separated by ion exchange chromatography and detected by fluorescence, and the protein content was quantified by the method of Lowry. Results: In general, the typical amino acid pattern of the intestinal mucosa was seen, with very high levels of taurine, aspartate and glutamic acid. The main difference, as compared to a reference series of healthy subjects, was the elevated glutamine concentration of the duodenal mucosa. This amino acid was unaltered in the descending colon and depressed in the rectum. At the same time, the glutamatic acid concentrations were unaltered, suggesting that the degradation of glutamine was not increased in the septic state of the majority of the patients studied. Phenylalanine and the two branched-chain amino acids, valine and leucine, were elevated in the duodenal mucosa, and in the colonic mucosa, methionine and phenylalanine were elevated; otherwise, all the other individual amino acids were unaltered or depressed. Conclusions: The alterations seen in mucosal free amino acid and protein concentrations in connection with critical illness are different in many respects and contrast with the findings seen after starvation or moderate surgical trauma.

  • 36. Ahlstrand, Tuuli
    et al.
    Tuominen, Heidi
    Beklen, Arzu
    Torittu, Annamari
    Oscarsson, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Sormunen, Raija
    Pöllänen, Marja T.
    Permi, Perttu
    Ihalin, Riikka
    A novel intrinsically disordered outer membrane lipoprotein of Aggregatibacter actinomycetemcomitans binds various cytokines and plays a role in biofilm response to interleukin-1β and interleukin-82017Ingår i: Virulence, ISSN 2150-5594, E-ISSN 2150-5608, Vol. 8, nr 2, s. 115-134Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Intrinsically disordered proteins (IDPs) do not have a well-defined and stable 3-dimensional fold. Some IDPs can function as either transient or permanent binders of other proteins and may interact with an array of ligands by adopting different conformations. A novel outer membrane lipoprotein, bacterial interleukin receptor I (BilRI) of the opportunistic oral pathogen Aggregatibacter actinomycetemcomitans binds a key gatekeeper proinflammatory cytokine interleukin (IL)-1β. Because the amino acid sequence of the novel lipoprotein resembles that of fibrinogen binder A of Haemophilus ducreyi, BilRI could have the potential to bind other proteins, such as host matrix proteins. However, from the tested host matrix proteins, BilRI interacted with neither collagen nor fibrinogen. Instead, the recombinant non-lipidated BilRI, which was intrinsically disordered, bound various pro/anti-inflammatory cytokines, such as IL-8, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10. Moreover, BilRI played a role in the in vitro sensing of IL-1β and IL-8 because low concentrations of cytokines did not decrease the amount of extracellular DNA in the matrix of bilRI− mutant biofilm as they did in the matrix of wild-type biofilm when the biofilms were exposed to recombinant cytokines for 22 hours. BilRI played a role in the internalization of IL-1β in the gingival model system but did not affect either IL-8 or IL-6 uptake. However, bilRI deletion did not entirely prevent IL-1β internalization, and the binding of cytokines to BilRI was relatively weak. Thus, BilRI might sequester cytokines on the surface of A. actinomycetemcomitans to facilitate the internalization process in low local cytokine concentrations.

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  • 37.
    Ahlström, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för biologisk grundutbildning.
    Testing the specificity of the pBAD arabinose reporter2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The project highlights Salmonella enterica subspecies enterica serovar Typhimurium (S. Tm)'s ability to metabolize simple sugars released from dead commensal bacteria, by using the pBAD (araBAD promoter) system as a reporter of L-arabinose availability. Using bioinformatics and homology of conserved L-arabinose transporter genes shared in Escherichia coli K12 (E. coli) and S. Tm, we aimed to create a S. Tm mutant strain unable to obtain L-arabinose from it environment. During the projects course of time it was discovered that L-arabinose transporters are not a shared gene trait between E. coli and S. Tm, and that putative L-arabinose transporter orthologues may exists in the S. Tm genome.

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  • 38.
    Ahlsén, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Structure-activity and resistance studies of HIV-1 protease inhibitors2000Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The present investigation was undertaken in order to identify inhibitors of HIV-1 protease that would be efficient in vivo and against HIV-1 protease carrying mutations known to confer resistance to inhibitors in clinical use. A second interest was to understand details of inhibitory mechanisms and to gain understanding of the molecular details of resistance.

    Linear inhibitors of transition-state type showed to have a resistance pattern similar to protease inhibitors in clinical use, whereas cyclic inhibitors of sulfonamide were somewhat different in their inhibitory profiles. It was found that mutation L90M in some situations could lessen the decrease in overall efficiency suffered by the enzyme when aquiring other mutations. Also presented are results from the characterization of double mutation I84V/L90M, formerly not investigated. Testing of triple and quadruple mutant confirmed the additive features of some mutations. In an attempt to find new leads for inhibitor development, extracts from bee propolis, a natural product, was investigated, and it was found that one extract inhibited wild-type enzyme with an I50-value of 0.2 μg/mL. Even more interesting is the result that propolis extract also inhibited all the investigated mutant enzymes.

  • 39.
    Ahlsén, Hanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    The Effects of Abiotic Stress on Alternative Splicing in Non-specific Lipid Transfer Proteins in Marchantia polymorpha2018Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Due to global warming, our planet will experience more extreme weather conditions. Plants can protect themselves against these abiotic stress conditions with their stress response, which includes alternative splicing of certain genes. Alternative splicing is a post-transcriptional process where a single gene gives rise to different mRNAs, which in turn produces different proteins. In plants, this is usually done by intron retention. One type of protein that may be involved in this stress response are the non-specific lipid transfer proteins (LTPs). Indeed, evidence of intron retention has been found in the LTP genes in the liverwort Marchantia polymorpha, called MpLTPd. To investigate whether this alternative splicing is caused by abiotic stress or not, I subjected the moss to two different types of stress trials, drought and cold, and compared the general expression of the intron in MpLTPd2 and MpLTPd3 from the stressed samples to samples from a moss grown under normal conditions. I found that the expression of the intron did change in the stressed moss, but none of the differences were significant. This suggests that alterative splicing in MpLTPd2 and MpLTPd3 is not caused by cold and drought and that the intron-containing protein plays no role in the protection of M. polymorpha against abiotic stress.

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  • 40.
    Ahmad, Shabbir
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Hysteretic Behavior, Regioselectivity, and Role of Salt Bridging Residues at the Domain Interface of Potato Epoxide Hydrolase StEH1, Site-Directed Mutagenesis and Kinetic Study2009Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
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  • 41.
    Ahmadova, Nigar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Mamedov, Fikret
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Formation of tyrosine radicals in photosystem II under far-red illumination2018Ingår i: Photosynthesis Research, ISSN 0166-8595, E-ISSN 1573-5079, Vol. 136, nr 1, s. 93-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photosystem II (PS II) contains two redox-active tyrosine residues on the donor side at symmetrical positions to the primary donor, P680. TyrZ, part of the water-oxidizing complex, is a preferential fast electron donor while TyrD is a slow auxiliary donor to P680 +. We used PS II membranes from spinach which were depleted of the water oxidation complex (Mn-depleted PS II) to study electron donation from both tyrosines by time-resolved EPR spectroscopy under visible and far-red continuous light and laser flash illumination. Our results show that under both illumination regimes, oxidation of TyrD occurs via equilibrium with TyrZ at pH 4.7 and 6.3. At pH 8.5 direct TyrD oxidation by P680 + occurs in the majority of the PS II centers. Under continuous far-red light illumination these reactions were less effective but still possible. Different photochemical steps were considered to explain the far-red light-induced electron donation from tyrosines and localization of the primary electron hole (P680 +) on the ChlD1 in Mn-depleted PS II after the far-red light-induced charge separation at room temperature is suggested.

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  • 42. Ahmed, Aisha S
    et al.
    Li, Jian
    Erlandsson-Harris, Helena
    Stark, André
    Bakalkin, Georgy
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Mahmood, Ahmed
    Suppression of pain and joint destruction by inhibition of the proteasome system in experimental osteoarthritis2012Ingår i: Pain, ISSN 0304-3959, E-ISSN 1872-6623, Vol. 153, nr 1, s. 18-26Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Osteoarthritis is a degenerative joint disease with pain and loss of joint function as major pathological features. Recent studies show that proteasome inhibitors reduce pain in various pathological conditions. We evaluated the effects of MG132, a reversible proteasome inhibitor on pain and joint destruction in a rat model of osteoarthritis. Osteoarthritis was induced by intraarticular injection of monosodium iodoacetate into the rat knee. Knee joint stiffness was scored and nociception was evaluated by mechanical pressure applied to the respective hind paw. Knee joint destruction was assessed by radiological and histological analyses. Expression of matrix metalloproteinase-3 (MMP-3) was analyzed by quantitative reverse transcription polymerase chain reaction in the knee articular cartilage. Expression of substance P (SP) and calcitonin gene-related peptide (CGRP) was studied in the dorsal root ganglia (L4–L6) by quantitative reverse transcription polymerase chain reaction and in the knee joints by immunohistochemistry. Our results indicate that daily treatment of osteoarthritic rats with MG132 significantly increases their mobility while the swelling, pain thresholds, and pathological features of the affected joints were reduced. Furthermore, the upregulated expression of MMP-3, SP, and CGRP in the arthritic rats was normalized by MG132 administration. We conclude that the proteasome inhibitor MG132 reduces pain and joint destruction, probably by involving the peripheral nervous system, and that changes in SP and CGRP expression correlate with alterations in behavioural responses. Our findings suggest that nontoxic proteasome inhibitors may represent a novel pharmacotherapy for osteoarthritis.

  • 43. Ahn, Young O.
    et al.
    Mahinthichaichan, Paween
    Lee, Hyun Ju
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Ouyang, Hanlin
    Kaluka, Daniel
    Yeh, Syun-Ru
    Arjona, Davinia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Rousseau, Denis L.
    Tajkhorshid, Emad
    Ädelroth, Pia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Gennis, Robert B.
    Conformational coupling between the active site and residues within the K-C-channel of the Vibrio cholerae cbb(3)-type (C-family) oxygen reductase2014Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, nr 42, s. E4419-E4428Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The respiratory chains of nearly all aerobic organisms are terminated by proton-pumping heme-copper oxygen reductases (HCOs). Previous studies have established that C-family HCOs contain a single channel for uptake from the bacterial cytoplasm of all chemical and pumped protons, and that the entrance of the K-C-channel is a conserved glutamate in subunit III. However, the majority of the K-C-channel is within subunit I, and the pathway from this conserved glutamate to subunit I is not evident. In the present study, molecular dynamics simulations were used to characterize a chain of water molecules leading from the cytoplasmic solution, passing the conserved glutamate in subunit III and extending into subunit I. Formation of the water chain, which controls the delivery of protons to the K-C-channel, was found to depend on the conformation of Y241(Vc), located in subunit I at the interface with subunit III. Mutations of Y241(Vc) (to A/F/H/S) in the Vibrio cholerae cbb(3) eliminate catalytic activity, but also cause perturbations that propagate over a 28-angstrom distance to the active site heme b(3). The data suggest a linkage between residues lining the KC-channel and the active site of the enzyme, possibly mediated by transmembrane helix alpha 7, which contains both Y241(Vc) and the active site crosslinked Y255(Vc), as well as two Cu-B histidine ligands. Other mutations of residues within or near helix alpha 7 also perturb the active site, indicating that this helix is involved in modulation of the active site of the enzyme.

  • 44.
    Ahnoff, Martin
    et al.
    Univ Gothenburg, Dept Chem Mol Biol, SE-41296 Gothenburg, Sweden.;Denator AB, Gothenburg, Sweden..
    Cazares, Lisa H.
    US Army Med Res Inst Infect Dis, Mol & Translat Sci, Frederick, MD 21702 USA.;US Army Med Res & Mat Command, DoD Biotechnol High Performance Comp Software App, Telemed & Adv Technol Res Ctr, Ft Detrick, MD 21702 USA..
    Sköld, Karl
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinska vetenskaper, Cancerfarmakologi och beräkningsmedicin. Denator AB, Gothenburg, Sweden.;Uppsala Univ, Dept Med Sci Canc Pharmacol & Computat Med, Uppsala, Sweden..
    Thermal inactivation of enzymes and pathogens in biosamples for MS analysis2015Ingår i: Bioanalysis, ISSN 1757-6180, E-ISSN 1757-6199, Vol. 7, nr 15, s. 1885-1899Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Protein denaturation is the common basis for enzyme inactivation and inactivation of pathogens, necessary for preservation and safe handling of biosamples for downstream analysis. While heat-stabilization technology has been used in proteomic and peptidomic research since its introduction in 2009, the advantages of using the technique for simultaneous pathogen inactivation have only recently been addressed. The time required for enzyme inactivation by heat (approximate to 1 min) is short compared with chemical treatments, and inactivation is irreversible in contrast to freezing. Heat stabilization thus facilitates mass spectrometric studies of biomolecules with a fast conversion rate, and expands the chemical space of potential biomarkers to include more short-lived entities, such as phosphorylated proteins, in tissue samples as well as whole-blood (dried blood sample) samples.

  • 45.
    Ahrenstedt, Lage
    KTH, Skolan för bioteknologi (BIO).
    Surface modification of cellulose materials: from wood pulps to artificial blood vessels2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes the improvement of two radically different cellulose materials, paper and artificial blood vessels, constructed from two diverse cellulose sources, wood pulp and Acetobacter xylinum. The improvement of both materials was possible due to the natural affinity of the hemicellulose xyloglucan for cellulose.

    Chemical and mechanical pulps were treated with xyloglucan in the wet-end prior to hand sheet formation or by spray application of dry hand sheets, loading a comparable amount of xyloglucan. The tensile strength increases for the wet-end treatment and spray application were 28% and 71% respectively for bleached soft wood, compared to untreated sheets (20.7 Nm/g). The corresponding strength increases for hand sheets made of thermo-mechanical pulp were 6% and 13% respectively compared to untreated sheets (42.4 Nm/g). The tendency for chemical pulp to be superior to mechanical pulp with respect to strength increase was valid even for tear strength and Scott-Bond. These results suggest, in agreement with other studies, that adhesion of xyloglucan to wood fibres is dependent on their degree of surface lignification.

    Also, a method was developed to increase the blood compatibility of artificial blood vessels constructed of bacterial cellulose. Xyloglucan was covalently linked to the endothelial cell adhesion motif (Arg-Gly-Asp). To obtain this, new solid-phase coupling chemistry was developed. Xyloglucan oligosaccharides (XGO) were transformed into XGO-succinamic acid via the corresponding XGO--NH2 derivative prior to coupling with the N-terminus of the solid-phase synthesised Gly-Arg-Gly-Asp-Ser peptide. The resin-bound glyco-peptide was then cleaved and enzymatically re-incorporated into high molecular weight xyloglucan. The glyco-peptide was further adsorbed onto bacterial cellulose scaffolds, increasing the adhesion and proliferation of endothelial cells and therefore blood compatibility.

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  • 46. Aili, Daniel
    et al.
    Enander, Karin
    Baltzer, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Liedberg, Bo
    Synthetic de novo designed polypeptides for control of nanoparticle assembly and biosensing2007Ingår i: Biochemical Society Transactions, ISSN 0300-5127, E-ISSN 1470-8752, Vol. 35, nr 3, s. 532-534Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This contribution describes how de novo designed synthetic helix–loop–helix polypeptides are utilized tocontrol the assembly of gold nanoparticles and as scaffolds for biosensing. The synthetic polypeptides aredesigned to fold into a four-helix bundle upon dimerization. When immobilized on gold nanoparticles,dimerization and folding occur between peptides on neighbouring particles as an effect of particleaggregation and the folded polypeptides are rigid enough to keep the particles separated at a distancecorresponding to the size of the four-helix bundle. Moreover, peptide dimerization offers a convenientroute to assemble nanoparticles into hybrid multilayers on planar substrates. The drastic change in theresonance conditions of the localized nanoparticle surface plasmon upon particle aggregation is shown tobe useful for optical detection of biomolecular interactions.

  • 47.
    Aisenbrey, Christopher
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bechinger, Burkhard
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Macromolecular Crowding at Membrane Interfaces: Adsorption and Alignment of Membrane Peptides2008Ingår i: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 375, s. 376-385Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Association of proteins to cellular membranes is involved in various biological processes. Various theoretical models have been developed to describe this adsorption mechanism, commonly implying the concept of an ideal solution. However, due to the two-dimensional character of membrane surfaces intermolecular interactions between the adsorbed molecules become important. Therefore previously adsorbed molecules can influence the adsorption behavior of additional protein molecules and their membrane-associated structure. Using the model peptide LAH4, which upon membrane-adsorption can adopt a transmembrane as well as an in-planar configuration, we carried out a systematic study of the correlation between the peptide concentration in the membrane and the topology of this membrane-associated polypeptide. We could describe the observed binding behavior by establishing a concept, which includes intermolecular interactions in terms of a scaled particle theory.

    High surface concentration of the peptide shifts the molecules from an in-planar into a transmembrane conformation, a process driven by the reduction of occupied surface area per molecule. In a cellular context, the crowding-dependent alignment might provide a molecular switch for a cell to sense and control its membrane occupancy. Furthermore, crowding might have pronounced effects on biological events, such as the cooperative behavior of antimicrobial peptides and the membrane triggered aggregation of amyloidogenic peptides.

  • 48.
    Aisenbrey, Christopher
    et al.
    Institut de Chimie Universit0 Louis Pasteur Strasbourg—CNRS, UMR 7177 4, Rue Blaise Pascal, 67000 Strasbourg (France); Max-Planck-Institut f>r Biochemie Am Klopferspitz 18A, 82152 Martinsried (Germany).
    Cusan, Monica
    Lambotte, Stephan
    Jasperse, Pieter
    Georgescu, Julia
    Harzer, Ulrike
    Bechinger, Burkhard
    Specific Isotope Labeling of Colicin E1 and B Channel Domains For Membrane Topological Analysis by Oriented Solid-State NMR Spectroscopy2008Ingår i: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, nr 6, s. 944-951Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An approach is presented to selectively label the methionines of the colicin E1 and B channel domains, each about 200 residues in size, and use them for oriented solid-state NMR investigations. By combining site-directed mutagenesis, bacterial overexpression in a methionine auxotroph E. coli strain and biochemical purification, quantitative amounts of the proteins for NMR structural investigations were obtained. The proteins were selectively labeled with 15N at only one, or at a few, selected sites. Multidimensional heteronuclear correlation high-resolution NMR spectroscopy and mass spectrometry were used to monitor the quality of isotopic labeling. Thereafter the proteins were reconstituted into oriented phospholipid bilayers and investigated by proton-decoupled 15N solid-state NMR spectroscopy. The colicin E1 thermolytic fragment that carries a single 15N methionine within its hydrophobic helix 9 region exhibited 15N resonances that are characteristic of helices that are oriented predominantly parallel to the membrane surface at low temperature, and a variety of alignments and conformations at room temperature. This suggests that the protein can adopt both umbrella and pen-knife conformations.

  • 49.
    Akhras, Michael S.
    KTH, Skolan för bioteknologi (BIO).
    Nucleic Acid Based Pathogen Diagnostics2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Patogena organismer smittas till värd organismen genom alla möjliga kontaktnätverk och skapar en mångfald olika sjukdomstillstånd. Dock är det fortfarande vanligt förekommande behandlingsbara infektiösa sjukdomar som orsakar den största hälsoförlusten, sett från ett globalt perspektiv. Bill och Melinda Gates Stiftelsen samarbetade med RAND kooperation för att forma “The Global Health Diagnostics Forum”. Deras mål var att etablera och analysera matematiska modeller för vilka effekter en ny diagnostisk metod utrustat för fältarbete skulle ha i utvecklingsländer. Resultaten var häpnadsveckande, med potentiellt miljoner av liv som skulle kunna räddas på en årlig basis.

    Den etablerade standarden för diagnostik av patogena bakterier har länge varit kultiveringsmedia baserad. Miljö specialiserade biologer har estimerat att mindre än 1 % av alla bakterie arter går att kultivera. Dock erbjuder genetiska analyser potentialen att kunna identifiera alla mikrober från alla de biologiska rikena. Nukleinsyrebaserade diagnostiska metoder har märkbart förbättrats över de senaste årtionden. Nya tekniker erbjuder utökad sensitivitet, selektivitet, sänkta kostnader och parallella analyser av patient prover. Dock är de flesta metoderna begränsade till standardiserade laboratoriemiljöer. För att konstruera en väl fungerande diagnostisk fältutrustning för användning i problem områden, behöver världsledande tekniker identifieras och kombineras.

    Fokuseringsområdet för denna doktorsavhandling har varit att utveckla och utföra nukleinsyrebaserade metoder för patogen diagnostik. Metoder och experimentella utförande applicerades på två distinkta system i) sökning av antibiotika resistens relaterade mutationer i den patogena bakterien Neisseria gonorrhoeae och ii) genotypning av det cancer orsakande Humana Papillomaviruset (HPV). Den första delen av studien inriktade sig mot utveckling av snabba, direkta och multiplexa Pyrosekvenserings baserade nukleinsyreanalyser. Med förbättrad provprepareringsmetodologi kunde vi detektera multipla HPV infektioner med högre sensitivitet än vad tidigare beskrivits med liknande metodologi. Den andra delen av studien fokuserades på multiplexa nukleinsyre amplifikationer med “Molecular Inversion Probe” tekniken med sista steg Pyrosekvenserings analys. “PathogenMip assay” erbjuder ett komplett detektionsprotokoll för alla kända patogena organismer. Vi introducerar även den nya “Connector Inversion Probe”, en “Padlock Probe” kapabel att genomföra kompletta gap fyllningar för multiplex nukleinsyre amplifiering.

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  • 50.
    Akinbomi, Julius
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Brandberg, Tomas
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Sanni, Adebayo
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Development and dissemination strategies for accelerating biogas production in Nigeria2014Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, nr 3, s. 5707-5737Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Following the worsening energy crisis of unreliable electricity and unaffordable petroleum products coupled with the increase number of poverty-stricken people in Nigeria, the populace is desperately in need of cheap alternative energy supplies that will replace or complement the existing energy sources. Previous efforts by the government in tackling the challenge by citizenship sensitization of the need for introduction of biofuel into the country’s energy mix have not yielded the expected results because of a lack of sustained government effort. In light of the shortcomings, this study assesses the current potential of available biomass feedstock for biogas production in Nigeria, and further proposes appropriate biogas plants, depending on feedstock type and quantity, for the six geopolitical zones in Nigeria. Besides, the study proposes government-driven biogas development systems that could be effectively used to harness, using biogas technology, the estimated 270 TWh of potential electrical energy from 181 million tonnes of available biomass, in the advancement of electricity generation and consequent improvement of welfare in Nigeria.

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