| 21. |
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| 22. |
- Stenberg, Simon, et al.
(författare)
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Control of mitochondrial superoxide production includes programmed mtDNA deletion and restoration
- 2020
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Deletion of mitochondrial DNA in eukaryotes is mainly attributed to rare accidental events associated with mitochondrial replication or repair of double-strand breaks. We report the discovery that yeast cells arrest harmful intramitochondrial superoxide production by shutting down respiration through genetically controlled deletion of mitochondrial oxidative phosphorylation genes. We show that the regulatory circuitry underlying this editing critically involves the antioxidant enzyme superoxide dismutase 2 and two-way mitochondrial-nuclear communication. While mitochondrial DNA homeostasis is rapidly restored after cessation of a short-term superoxide stress, long-term stress causes maladaptive persistence of the deletion process, leading to complete annihilation of the cellular pool of intact mitochondrial genomes and irrevocable loss of respiratory ability. Our results may therefore be of etiological as well as therapeutic importance with regard to age-related mitochondrial impairment and disease.One-Sentence SummaryGenetically controlled editing of mitochondrial DNA is an integral part of the yeast’s defenses against oxidative damage.
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| 23. |
- Wieloch, Thomas, 1979-, et al.
(författare)
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Intramolecular carbon isotope signals reflect metabolite allocation in plants
- 2022
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Ingår i: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 73:8, s. 2558-2575
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Stable isotopes at natural abundance are key tools to study physiological processes occurring outside the temporal scope of manipulation and monitoring experiments. Whole-molecule carbon isotope ratios (13C/12C) enable assessments of plant carbon uptake yet conceal information about carbon allocation. Here, we identify an intramolecular 13C/12C signal at tree-ring glucose C-5 and C-6 and develop experimentally testable theories on its origin. More specifically, we assess the potential of processes within C3 metabolism for signal introduction based (inter alia) on constraints on signal propagation posed by metabolic networks. We propose that the intramolecular signal reports carbon allocation into major metabolic pathways in actively photosynthesizing leaf cells including the anaplerotic, shikimate, and non-mevalonate pathway. We support our theoretical framework by linking it to previously reported whole-molecule 13C/12C increases in cellulose of ozone-treated Betula pendula and a highly significant relationship between the intramolecular signal and tropospheric ozone concentration. Our theory postulates a pronounced preference for leaf cytosolic triose-phosphate isomerase to catalyse the forward reaction in vivo (dihydroxyacetone phosphate to glyceraldehyde 3-phosphate). In conclusion, intramolecular 13C/12C analysis resolves information about carbon uptake and allocation enabling more comprehensive assessments of carbon metabolism than whole-molecule 13C/12C analysis.
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| 24. |
- Alström, Per, et al.
(författare)
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Multilocus phylogeny of the avian family Alaudidae (larks) reveals complex morphological evolution, non-monophyletic genera and hidden species diversity
- 2013
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 69:3, s. 1043-1056
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Tidskriftsartikel (refereegranskat)abstract
- The Alaudidae (larks) is a large family of songbirds in the superfamily Sylvioidea. Larks are cosmopolitan, although species-level diversity is by far largest in Africa, followed by Eurasia, whereas Australasia and the New World have only one species each. The present study is the first comprehensive phylogeny of the Alaudidae. It includes 83.5% of all species and representatives from all recognised genera, and was based on two mitochondrial and three nuclear loci (in total 6.4 kbp, although not all loci were available for all species). In addition, a larger sample, comprising several subspecies of some polytypic species was analysed for one of the mitochondrial loci. There was generally good agreement in trees inferred from different loci, although some strongly supported incongruences were noted. The tree based on the concatenated multilocus data was overall well resolved and well supported by the data. We stress the importance of performing single gene as well as combined data analyses, as the latter may obscure significant incongruence behind strong nodal support values. The multilocus tree revealed many unpredicted relationships, including some non-monophyletic genera (Calandrella, Mirafra, Melanocorypha, Spizocorys). The tree based on the extended mitochondrial data set revealed several unexpected deep divergences between taxa presently treated as conspecific (e.g. within Ammomanes cinctura, Ammomanes deserti, Calandrella brachydactyla, Eremophila alpestris), as well as some shallow splits between currently recognised species (e.g. Certhilauda brevirostris-C semitorquata-C curvirostris; Calendulauda barlowi-C. erythrochlamys; Mirafra cantillans-M. javanica). Based on our results, we propose a revised generic classification, and comment on some species limits. We also comment on the extraordinary morphological adaptability in larks, which has resulted in numerous examples of parallel evolution (e.g. in Melanocorypha mongolica and Alauda leucoptera [both usually placed in Melanocorypha]; Ammomanopsis grayi and Ammomanes cinctura/deserti [former traditionally placed in Ammomanes]; Chersophilus duponti and Certhilauda spp.; Eremopterix hova [usually placed in Mirafra] and several Mirafra spp.), as well as both highly conserved plumages (e.g. within Mirafra) and strongly divergent lineages (e.g. Eremopterix hova vs. other Eremopterix spp.; Calandrella cinerea complex vs. Eremophila spp.; Eremalauda dunni vs. Chersophilus duponti; Melanocorypha mongolica and male M. yeltoniensis vs. other Melanocoupha spp. and female M. yeltoniensis). Sexual plumage dimorphism has evolved multiple times. Few groups of birds show the same level of disagreement between taxonomy based on morphology and phylogenetic relationships as inferred from DNA sequences. (C) 2013 Elsevier Inc. All rights reserved.
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| 25. |
- Lindahl, Björn, et al.
(författare)
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Fungal community analysis by high-throughput sequencing of amplified markers – a user's guide
- 2013
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 199:1, s. 288-299
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Forskningsöversikt (refereegranskat)abstract
- * Novel high-throughput sequencing methods outperform earlier approaches in terms of resolution and magnitude. They enable identification and relative quantification of community members and offer new insights into fungal community ecology. These methods are currently taking over as the primary tool to assess fungal communities of plant-associated endophytes, pathogens, and mycorrhizal symbionts, as well as free-living saprotrophs. * Taking advantage of the collective experience of six research groups, we here review the different stages involved in fungal community analysis, from field sampling via laboratory procedures to bioinformatics and data interpretation. We discuss potential pitfalls, alternatives, and solutions. * Highlighted topics are challenges involved in: obtaining representative DNA/RNA samples and replicates that encompass the targeted variation in community composition, selection of marker regions and primers, options for amplification and multiplexing, handling of sequencing errors, and taxonomic identification. * Without awareness of methodological biases, limitations of markers, and bioinformatics challenges, large-scale sequencing projects risk yielding artificial results and misleading conclusions.
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| 26. |
- Nilsson, R. Henrik, 1976, et al.
(författare)
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A software pipeline for processing and identification of fungal ITS sequences
- 2009
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Ingår i: Source Code for Biology and Medicine. - 1751-0473. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Fungi from environmental samples are typically identified to species level through DNA sequencing of the nuclear ribosomal internal transcribed spacer (ITS) region for use in BLAST-based similarity searches in the International Nucleotide Sequence Databases. These searches are time-consuming and regularly require a significant amount of manual intervention and complementary analyses. We here present software - in the form of an identification pipeline for large sets of fungal ITS sequences - developed to automate the BLAST process and several additional analysis steps. The performance of the pipeline was evaluated on a dataset of 350 ITS sequences from fungi growing as epiphytes on building material. Results The pipeline was written in Perl and uses a local installation of NCBI-BLAST for the similarity searches of the query sequences. The variable subregion ITS2 of the ITS region is extracted from the sequences and used for additional searches of higher sensitivity. Multiple alignments of each query sequence and its closest matches are computed, and query sequences sharing at least 50 % of their best matches are clustered to facilitate the evaluation of hypothetically conspecific groups. The pipeline proved to speed up the processing, as well as enhance the resolution, of the evaluation dataset considerably, and the fungi were found to belong chiefly to the Ascomycota, with Penicillium and Aspergillus as the two most common genera. The ITS2 was found to indicate a different taxonomic affiliation than did the complete ITS region for 10 % of the query sequences, though this figure is likely to vary with the taxonomic scope of the query sequences. Conclusions The present software readily assigns large sets of fungal query sequences to their respective best matches in the international sequence databases and places them in a larger biological context. The output is highly structured to be easy to process, although it still needs to be inspected and possibly corrected for the impact of the incomplete and sometimes erroneously annotated fungal entries in these databases. The open source pipeline is available for UNIX-type platforms, and updated releases of the target database are made available biweekly. The pipeline is easily modified to operate on other molecular regions and organism groups.
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| 27. |
- Andersson, Martin O., et al.
(författare)
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Molecular detection of Babesia capreoli and Babesia venatorum in wild Swedish roe deer, Capreolus capreolus
- 2016
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Ingår i: Parasites & Vectors. - : Springer Science and Business Media LLC. - 1756-3305. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The epidemiology of the zoonotic tick-transmitted parasite Babesia spp. and its occurrence in wild reservoir hosts in Sweden is unclear. In European deer, several parasite species, including Babesia capreoli and the zoonotic B. venatorum and B. divergens has been reported previously. The European roe deer, Capreolus capreolus, is an important and common part of the indigenous fauna in Europe, as well as an important host for Ixodes ricinus ticks, the vector of several Babesia spp. in Europe. Here, we aimed to investigate the occurrence of Babesia spp. in roe deer in Sweden. Findings: Roe deer (n = 77) were caught and sampled for blood. Babesia spp. was detected with a PCR assay targeting the 18S rRNA gene. The prevalence of Babesia spp. was 52 %, and two species were detected; B. capreoli and B. venatorum in 44 and 7.8 % of the individuals, respectively. Infection occurred both in summer and winter. Conclusions: We showed that roe deer in Sweden, close to the edge of their northern inland distributional range, are infected with Babesia spp. The occurrence of B. venatorum in roe deer imply that it is established in Sweden and the zoonotic implication of this finding should be regarded to a greater extent in future.
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| 28. |
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| 29. |
- Dukic Marinkov, Emilija, 1991, et al.
(författare)
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Chloroplast magnesium transporters play essential but differential roles in maintaining magnesium homeostasis
- 2023
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Ingår i: Frontiers in Plant Science. - 1664-462X. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Magnesium (Mg2+ ) is essential for photosynthesis in the chloroplasts of land plants and algae. Being the central ion of chlorophyll, cofactor and activator of many photosynthetic enzymes including RuBisCO, magnesium-deficient plants may suffer from leaf chlorosis symptoms and retarded growth. Therefore, the chloroplast Mg2+ concentration is tightly controlled by magnesium transport proteins. Recently, three different transporters from two distinct families have been identified in the chloroplast inner envelope of the model plant Arabidopsis thaliana: MGT10, MGR8, and MGR9. Here, we assess the individual roles of these three proteins in maintaining chloroplast Mg2+ homeostasis and regulating photosynthesis, and if their role is conserved in the model green alga Chlamydomonas reinhardtii. Phylogenetic analysis and heterologous expression revealed that the CorC-like MGR8 and MGR9 transport Mg2+ by a different mechanism than the CorA-like MGT10. MGR8 and MGT10 genes are highest expressed in leaves, indicating a function in chloroplast Mg2+ transport. MGR9 is important for chloroplast function and plant adaptation in conditions of deficiency or excess of Mg2+ . Transmission electron microscopy indicated that MGT10 plays a differential role in thylakoid stacking than MGR8 and MGR9. Furthermore, we report that MGR8, MGR9, and MGT10 are involved in building up the pH gradient across the thylakoid membrane and activating photoprotection in conditions of excess light, however the mechanism has not been resolved yet. While there are no chloroplast MGR-like transporters in Chlamydomonas, we show that MRS4 is a homolog of MGT10, that is required for photosynthesis and cell growth. Taken together, our findings reveal that the studied Mg2+ transporters play essential but differential roles in maintaining chloroplast Mg2+ homeostasis.
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| 30. |
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