| 1. |
- Amundsen, Silja Svanström, et al.
(författare)
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Four novel coeliac disease regions replicated in an association study of a Swedish-Norwegian family cohort.
- 2010
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Ingår i: Genes and immunity. - : Springer Science and Business Media LLC. - 1476-5470 .- 1466-4879. ; 11:1, s. 79-86
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Tidskriftsartikel (refereegranskat)abstract
- Recent genome-wide association studies have identified 1q31 (RGS1), 2q11-12 (IL18RAP), 3p21 (CCR1/CCR3/CCR2), 3q25-26 (IL12A/SCHIP1), 3q28 (LPP), 4q27 (IL2/IL21), 6q25 (TAGAP) and 12q24 (SH2B3) as susceptibility regions for coeliac disease (CD). We have earlier replicated association with the IL2/IL21 region. This study aimed at replicating the remaining regions in a family cohort using the transmission disequilibrium test, which is not prone to population stratification as a source of false-positive results. Nine single nucleotide polymorphisms (SNPs) within these regions were genotyped in 325 Swedish-Norwegian CD families. We found significant associations with the same alleles in the regions 1q31 (rs2816316; P(nc)=0.0060), 3p21 (rs6441961; P(nc)=0.0006), 3q25-26 (rs17810564; P(nc)=0.0316 and rs9811792; P(nc)=0.0434) and 3q28 (rs1464510; P(nc)=0.0037). Borderline, but non-significant, associations were found for rs917997 (IL18RAP), whereas no evidence for association could be obtained for rs13015714 (IL18RAP) or rs1738074 (TAGAP). The lack of replication of the latter SNPs could be because of limited power. rs3184504 (SH2B3) was not analysed because of assay failure. The most significantly associated region, 3p21 (CCR1/CCR3/CCR2), was further analysed by typing of 30 SNPs, with the aim of identifying the causal variant responsible for the initial association. Several SNPs showed association with CD, but none displayed associations stronger than rs6441961, nor did any of them add to the effect initially marked by rs6441961 in a conditional analysis. However, differential effects of rs6441961(*)C carrying haplotypes were indicated, and we thus cannot exclude the possibility that our inability to obtain evidence for multiple independent effects in the CCR1/CCR3/CCR2 gene region was related to a power issue.
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| 2. |
- Ottosson, Jakob, et al.
(författare)
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Bevattningsvatten : kunskapsunderlag
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Livsmedel från växtriket kan i vissa fall sprida mikrobiologisk smitta. Bär, bladgrönt och groddarmedför en särskild risk. Det beror på att de ofta äts råa eller efter minimal tillredning. Vi värmer deminte innan vi äter dem.Om livsmedlen är kontaminerade är det med stor sannolikhet orsakat av bevattningen. Vattnet kan havarit påverkat av avföring. Det kan också bero på spillning från vilda djur. Även naturgödsel kanförorena produkterna vid stänk från jord.Syftet med detta projekt var att se över kvaliteten på vatten för bevattning i Sverige. Vi ville koppladet till mikrobiologiska risker och utifrån det ta fram underlag till nationella råd och riktlinjer. Måletär ”en säkrare produktion av ätfärdiga bär och grönsaker som bättre förebygger sjukdomsutbrott”.Det visade sig att kvaliteten på vattnet generellt sett var god hos odlarna i projektet. Det samma gällergrödor. I vatten hittade vi enstaka sjukdomsframkallande mikroorganismer och ESBL-bildande E. coli.Dessa hittade vi dock endast i ytvatten som var mer förorenade av avföring och spillning. Men endastett fåtal prov på gröda visade på högre fekal förorening. Majoriteten av dessa kom från en och sammaodlare, som bevattnade med vatten från en damm. Vi hittade inga patogener på grödor. Däremot var ettprov på vitkål positivt för ESBL-bildande E. coli.Vi gjorde en kvantitativ riskvärdering av Shigatoxinproducerande E. coli (STEC) från isbergssallat.Den visade att även en liten förorening orsakad av avföring och utan påvisade STEC-bakterier ibevattningsvattnet kan utgöra en risk för mag-och tarminfektion. Riskvärderingen kan användas somunderlag för att föreslå mikrobiologiska kriterier, till exempel på vattenkvalitet. Vi behöver dockbeakta osäkerheterna med värderingen. De viktigaste osäkerheterna var utsöndringen av ochpatogeniciteten hos STEC från infekterade nötkreatur. Hur mycket av dessa fastnar på den bevattnadegrödan? Hur stor är sannolikheten att infekteras vid låga doser (enstaka STEC-bakterier)? Och hur storär risken av stänk från jord?Det finns olika åtgärder att ta till för att minska sannolikheten för utbrott och sjukdomsfall. Dessa är 1.Kriterier för vattenkvalitet. 2: Rening av vatten som inte uppnår dessa kriterier. 3. Införa enuppehållstid mellan sista bevattning och skörd. 4. Dessutom kan konsumenterna skölja produkternainnan de konsumerar dem. Det är också viktigt att se till att hålla utrustningen ren, exempelvis rör ochmunstycken. På så vis undviks föroreningar och tillväxt av bakterier.Om ytvatten måste användas för bevattning under de sista två veckorna innan skörd bör ettprovtagningsprogram utformas. Proven bör då visa på låg fekal förorening samt avsaknad avSalmonella. I bästa fall bör ytvatten renas före bevattning. Detta kan göras till exempel med hjälp avfotokatalys, UV-ljus eller filtrering. De sista två dagarna före skörd bör dock endast vatten avdricksvattenkvalitet användas.I en framtid med sjunkande grundvattennivåer, torrare somrar och blötare vintrar finns ett behov av attsamla in vatten för bevattning. Det bör göras under höstregn och vårfloder, samt vintertid. Vattnet fårsedan lagras i magasin. Vatten från bevattningsmagasin kan behöva renas innan det används förbevattning beroende på hur skyddat magasinet är från föroreningar.
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| 3. |
- Svanström, Åsa, et al.
(författare)
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Intracellular trehalase activity is required for development, germination and heat-stress resistance of Aspergillus niger conidia
- 2013
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Ingår i: Research in Microbiology. - : Elsevier BV. - 0923-2508 .- 1769-7123. ; 164, s. 91-99
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Tidskriftsartikel (refereegranskat)abstract
- The disaccharide trehalose is known as a stress protectant in several kinds of organisms, including fungi, where it is a major carbohydrate in resting structures, e.g. asexual conidia. The gene encoding the enzyme responsible for degradation of intracellular trehalose, treB, was deleted and the phenotype was analyzed in terms of morphology, trehalose content during conidial outgrowth and stress tolerance. The mutant conidiophores produced fewer and less viable spores, and during early stages of germination the internal levels of trehalose were higher compared to the wild type. When subjecting the mutant to various stresses (weak acid and salt), no increased sensitivity could be observed, but in line with previous observations, e.g. in Aspergillus nidulans, Aspergillus niger Delta treB spores in a very early stage of germination were less sensitive to heat stress. In contrast, when subjecting resting spores to 55 degrees C, an intact treB gene was essential for survival. This finding suggests that trehalose mobilization is required to facilitate cell recovery after heat-induced damage. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
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| 4. |
- Svanström, Åsa
(författare)
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Trehalose metabolism and stress resistance in Aspergillus niger
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Food spoilage by filamentous fungi, moulds, is a global issue of great significance. Mould growth can cause food losses due to deterioration, and adverse health effects due to toxin production. Conidia, asexual spores, are the main factors of dispersal and infection in most food-relevant moulds. They therefore constitute important objects of study when trying to improve food safety. This thesis sought to increase understanding of conidial germination and stress resistance in the common food spoilage mould Aspergillus niger, by investigating the inhibitory properties of phenyllactic acid, a lactic acid bacteria metabolite, as well as the role and metabolism of trehalose. This sugar is a major component of spores and well known for its ability to protect proteins and membranes against various kinds of abiotic stress. A thorough examination in A. niger revealed that it contains six genes involved in trehalose synthesis: tpsA-C and tppA-C. All genes were expressed during conidial germination, and conserved orthologues could be identified in related Aspergilli. However, when creating deletion mutants, only ΔtpsA, ΔtppA and ΔtppB had significantly lowered trehalose content. These three genes therefore seem to be most significant for trehalose accumulation. Degradation of internal trehalose is catalysed by trehalase; in A. niger this enzyme is encoded by treB. Studies of ΔtppA, ΔtppB and ΔtreB demonstrated that a functional synthesis as well as utilisation of trehalose is crucial for heat stress resistance of A. niger conidia. Inability to produce or degrade trehalose also negatively affects the ability of the fungus to generate conidia. Lactic acid bacteria (LAB) have long been used to ferment foods, thereby extending the shelf life. Several LAB metabolites with antifungal properties have been identified, but the underlying mechanisms of inhibition are largel unknown. We have investigated the effect of phenyllactic acid (PLA) on growth and development of single A. niger conidia. Results showed that PLA inhibits moulds in a manner similar to that of weak acid preservatives, such as benzoic acid; but it also strongly restricts asexual development at sub-inhibitory concentrations. This effect is not seen by other acids, and therefore indicates a unique mechanism of action for PLA.
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| 5. |
- Svanström, Åsa, et al.
(författare)
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Trehalose synthesis in Aspergillus niger: characterization of six homologous genes, all with conserved orthologs in related species
- 2014
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background: The disaccharide trehalose is a major component of fungal spores and is released upon germination. Moreover, the sugar is well known for is protective functions, e.g.against thermal stress and dehydration. The properties and synthesis of trehalose have been well investigated in the bakers' yeast Saccharomyces cerevisiae. In filamentous fungi, such knowledge is limited, although several gene products have been identified.Results: Using Aspergillus niger as a model fungus, the aim of this study was to provide an overview of all genes involved in trehalose synthesis. This fungus has three potential trehalose-6-phosphate synthase encoding genes, tpsA-C, and three putative trehalose phosphate phosphatase encoding genes, tppA-C, of which two have not previously been identified. Expression of all six genes was confirmed using real-time PCR, and conserved orthologs could be identified in related Aspergilli. Using a two-hybrid approach, there is a strong indication that four of the proteins physically interact, as has previously been shown in S. cerevisiae. When creating null mutants of all the six genes, three of them,Delta tpsA,Delta tppA and Delta tppB, had lower internal trehalose contents. The only mutant with a pronounced morphological difference was Delta tppA, in which sporulation was severely reduced with abnormal conidiophores. This was also the only mutant with accumulated levels of trehalose-6-phosphate, indicating that the encoded protein is the main phosphatase under normal conditions. Besides Delta tppA, the most studied deletion mutant in this work was Delta tppB. This gene encodes a protein conserved in filamentous Ascomycota. The Delta tppB mutant displayed a low, but not depleted, internal trehalose content, and conidia were more susceptible to thermal stress.Conclusion: A. niger contains at least 6 genes putatively involved in trehalose synthesis. Gene expressions related to germination have been quantified and deletion mutants characterized: Mutants lacking tpsA, tppA or tppB have reduced internal trehalose contents. Furthermore, tppA, under normal conditions, encodes the functional trehalose-6-phosphate-phosphatase.
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