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- Sawangproh, Weerachon, et al.
(författare)
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Gene transfer across species boundaries in bryophytes : evidence from major life cycle stages in Homalothecium lutescens and H. sericeum
- 2020
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 125:4, s. 565-579
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: The mosses Homalothecium lutescens and H. sericeum are genetically, morphologically and ecologically differentiated; mixed populations sometimes occur. In sympatric populations, intermediate character states among gametophytes and sporophytes have been observed, suggesting hybridization and introgression in such populations. Methods: We determined genotypes using bi-allelic co-dominant single nucleotide polymorphism (SNP) markers, specific to either H. lutescens or H. sericeum, to estimate the degree of genetic mixing in 449 moss samples collected from seven sympatric and five allopatric populations on the island of Öland, south Sweden. The samples represented three generations: haploid maternal gametophytes; diploid sporophytes; and haploid sporelings. Key Results: Admixture analyses of SNP genotypes identified a majority as pure H. lutescens or H. sericeum, but 76 samples were identified as mildly admixed (17 %) and 17 samples (3.8 %) as strongly admixed. Admixed samples were represented in all three generations in several populations. Hybridization and introgression were bidirectional. Conclusions: Our results demonstrate that admixed genomes are transferred between the generations, so that the populations behave as true hybrid zones. Earlier studies of sympatric bryophyte populations with admixed individuals have not been able to show that admixed alleles are transferred beyond the first generation. The presence of true hybrid zones has strong evolutionary implications because genetic material transferred across species boundaries can be directly exposed to selection in the long-lived haploid generation of the bryophyte life cycle, and contribute to local adaptation, long-term survival and speciation.
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- Vogelmann, T C, et al.
(författare)
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Plants as light traps
- 1986
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 68:4, s. 704-708
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Tidskriftsartikel (refereegranskat)
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- Fall, Katja
(författare)
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Medical interventions and gastric cancer risk : an observational approach
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Helicobacter pylori infection is undoubtedly the most important risk factor for gastric cancer. A causal relationship with gastric cancer, however, has not been clearly established and the carcinogenic mechanism is still ambiguous. There is a growing consensus for introduction of large-scale eradication programs, but it is yet unknown if elimination of H. pylori would reduce the incidence of gastric cancer. To address this question, randomized intervention trials using gastric cancer as end-point have been initiated, but conclusive results will not be available in the near future since these trials require very large samples and lengthy follow-up. Using observational data on medical interventions, the aim of this thesis was to investigate characteristics of the relationship between H. pylori infection and gastric cancer, and to assess the risk of gastric cancer following antibiotic and anti-inflammatory treatments. In a previous cohort study of 39,000 hip replacement patients, identified in the Swedish Inpatient Register, a declining risk of gastric cancer was observed with increasing time after hip surgery. Here, we tested the hypothesis that the risk reduction was mediated through incidental eradication of H. pylori, caused by the prophylactic antibiotic treatment given at time of surgery. In a case-control study, 'nested' within the original cohort (174 cases, 462 controls), we found that both long-term antibiotic treatment before surgery (OR, 0.3 95% Cl, 0. 1-0.7) and prophylactic antibiotic treatment (OR, 0.7 95% Cl, 0.5- 1. 1) conferred a reduction in gastric cancer risk. To further test the hypothesis that exposure to heavy antibiotic treatment reduces the risk of gastric cancer, we assessed cancer risk among 336,017 patients hospitalized for one of ten selected infectious diseases, identified in the Swedish Inpatient Register. The gastric cancer risk in the infectious disease cohort was similar to that expected in the background population, and the data did thus not further support our hypothesis. As an alternative explanation, the apparent reduction in gastric cancer risk may have resulted from intense exposure to aspirin and other non-steroid anti-inflammatory drugs used by the hip replacement patients, who typically have intractable pain prior to their operations. Analysis of data from a population-based case-control study (567 cases, 1165 controls) showed a 30% (OR, 0.7 95% Cl, 0.6-1.0) reduced gastric cancer risk among users of aspirin compared to non-users, as well as an inverse trend with increased number of tablets used (p=0.02). Although largely unclear, the carcinogenic action of H. pylori is believed to be mediated through induction and maintenance of chronic inflammation. We aimed to test whether a noninfectious chronic inflammation, i.e. reactive gastritis induced by duodeno-gastric bile reflux following cholecystectomy, also increases the risk of gastric cancer. To address this issue, we assessed the gastric cancer risk within a cohort of 251,672 cholecystecomized patients that were followed for up to 27 years after surgery. A modest excess risk of gastric cancer was observed, but the association was inconsistent over gender strata and disappeared over time. Although not discarding the prospect of gastric cancer prevention by eradication of H. pylori, neither do these results unambiguously support the notion that antibiotic treatment reduces the risk of gastric cancer. Highlighting the role of inflammation - possibly H. pylori specific - a protective effect of nonsteroid anti-inflammatory drugs (aspirin) on gastric carcinogenesis was suggested.
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- Flanagan, Erin, et al.
(författare)
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Exposure to local, source-specific ambient air pollution during pregnancy and autism in children : a cohort study from southern Sweden
- 2023
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Evidence of air pollution exposure, namely, ambient particulate matter (PM), during pregnancy and an increased risk of autism in children is growing; however, the unique PM sources that contribute to this association are currently unknown. The aim of the present study was to investigate local, source-specific ambient PM exposure during pregnancy and its associations with childhood autism, specifically, and autism spectrum disorders (ASD) as a group. A cohort of 40,245 singleton births from 2000 to 2009 in Scania, Sweden, was combined with data on locally emitted PM with an aerodynamic diameter < 2.5 µm (PM2.5). A flat, two-dimensional dispersion model was used to assess local PM2.5 concentrations (all-source PM2.5, small-scale residential heating- mainly wood burning, tailpipe exhaust, and vehicle wear-and-tear) at the mother’s residential address during pregnancy. Associations were analyzed using binary logistic regression. Exposure to local PM2.5 during pregnancy from each of the investigated sources was associated with childhood autism in the fully adjusted models. For ASD, similar, but less pronounced, associations were found. The results add to existing evidence that exposure to air pollution during pregnancy may be associated with an increased risk of childhood autism. Further, these findings suggest that locally produced emissions from both residential wood burning and road traffic-related sources (tailpipe exhaust and vehicle wear-and-tear) contribute to this association.
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- Zdyb, Anna, et al.
(författare)
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Allene oxide synthase, allene oxide cyclase and jasmonic acid levels in Lotus japonicus nodules
- 2018
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Jasmonic acid (JA), its derivatives and its precursor cis-12-oxo phytodienoic acid (OPDA) form a group of phytohormones, the jasmonates, representing signal molecules involved in plant stress responses, in the defense against pathogens as well as in development. Elevated levels of JA have been shown to play a role in arbuscular mycorrhiza and in the induction of nitrogen-fixing root nodules. In this study, the gene families of two committed enzymes of the JA biosynthetic pathway, allene oxide synthase (AOS) and allene oxide cyclase (AOC), were characterized in the determinate nodule-forming model legume Lotus japonicus JA levels were to be analysed in the course of nodulation. Since in all L. japonicus organs examined, JA levels increased upon mechanical disturbance and wounding, an aeroponic culture system was established to allow for a quick harvest, followed by the analysis of JA levels in whole root and shoot systems. Nodulated plants were compared with non-nodulated plants grown on nitrate or ammonium as N source, respectively, over a five week-period. JA levels turned out to be more or less stable independently of the growth conditions. However, L. japonicus nodules formed on aeroponically grown plants often showed patches of cells with reduced bacteroid density, presumably a stress symptom. Immunolocalization using a heterologous antibody showed that the vascular systems of these nodules also seemed to contain less AOC protein than those of nodules of plants grown in perlite/vermiculite. Hence, aeroponically grown L. japonicus plants are likely to be habituated to stress which could have affected JA levels.
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