| 1. |
- Elfverson, Martin, et al.
(författare)
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Neurosteroids allosterically modulate the ion pore of the NMDA receptor consisting of NR1/NR2B but not NR1/NR2A
- 2008
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 372:2, s. 305-308
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Tidskriftsartikel (refereegranskat)abstract
- Neurosteroids are endogenously derived compounds, mediating rapid effects in the central nervous system. They participate in vital processes, including memory and learning, neuroplasticity, and neuroprotection in Alzheimer's disease. However, the mechanisms behind those effects remain to be elucidated. The neurosteroids pregnenolone sulphate (PS) and pregnanolone sulphate (3alpha5betaS) have recently been shown to allosterically alter the NMDA receptor in nanomolar concentrations. Those studies featured ifenprodil, which is a dirty drug, with affinity to many targets. In this study we compare the NMDA receptors in the hippocampus to recombinant NMDA receptors, using [3H]-MK-801 as radioligand. The results show that neurosteroids modulate the ifenprodil binding kinetics in a narrow concentration interval, addressing it to the NR2B subunit, since no effects were recorded at recombinant NR1/NR2A receptors. The effects were also seen as changes in the manner ifenprodil displaced or induced the dissociation of [3H]-MK-801. It indicates that the neurosteroidal effects indeed alter the ion pore of the NMDA receptor, why it is reasonable to believe that these findings have physiological relevance.
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| 2. |
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| 3. |
- Linde, Anna-Malin, et al.
(författare)
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Complete genome characterisation of a Newcastle disease virus isolated during an outbreak in Sweden in 1997
- 2010
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Ingår i: Virus Genes. - : Springer Science and Business Media LLC. - 0920-8569 .- 1572-994X. ; 41, s. 165-173
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Tidskriftsartikel (refereegranskat)abstract
- The complete genome sequence of a Newcastle disease virus (NDV) isolated from a chicken in Sweden was determined and compared with other NDV sequences. The isolate was shown to belong to genotype VIIb, which arose in the Far East and spread around the world during the 1990s. It had a length of 15,192 bases and consisted of six genes in the order 3'-NP-P-M-F-HN-L-5'. The F protein cleavage site was 112-RRQRRF-117, corresponding to that of a virulent pathotype.
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| 4. |
- Linde, Anna-Malin, et al.
(författare)
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Early evolution of the land plant circadian clock
- 2017
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 216:2, s. 576-590
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Tidskriftsartikel (refereegranskat)abstract
- While angiosperm clocks can be described as an intricate network of interlocked transcriptional feedback loops, clocks of green algae have been modelled as a loop of only two genes. To investigate the transition from a simple clock in algae to a complex one in angiosperms, we performed an inventory of circadian clock genes in bryophytes and charophytes. Additionally, we performed functional characterization of putative core clock genes in the liverwort Marchantia polymorpha and the hornwort Anthoceros agrestis. Phylogenetic construction was combined with studies of spatiotemporal expression patterns and analysis of M. polymorpha clock gene mutants. Homologues to core clock genes identified in Arabidopsis were found not only in bryophytes but also in charophytes, albeit in fewer copies. Circadian rhythms were detected for most identified genes in M. polymorpha and A. agrestis, and mutant analysis supports a role for putative clock genes in M. polymorpha. Our data are in line with a recent hypothesis that adaptation to terrestrial life occurred earlier than previously expected in the evolutionary history of charophyte algae. Both gene duplication and acquisition of new genes was important in the evolution of the plant circadian clock, but gene loss has also contributed to shaping the clock of bryophytes.
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| 5. |
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| 6. |
- Linde, Anna-Malin, et al.
(författare)
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Evolutionary History of the Marchantia polymorpha Complex
- 2020
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- The potential role of introgression in evolution has gained increased interest in recent years. Although some fascinating examples have been reported, more information is needed to generalize the importance of hybridization and introgression for adaptive divergence. As limited data exist on haploid dominant species, we analyzed genomes of three subspecies of the liverwort Marchantia polymorpha. We used available genomic data for subsp. ruderalis and carried out whole-genome (PacBio) sequencing for one individual each of subsp. montivagans and subsp. polymorpha as well as Illumina resequencing of additional genomes for all three subspecies. The three subspecies were compared against M. paleacea as outgroup. Our analyses revealed separation of the three taxa, but all three possible topologies were richly represented across the genomes, and the underlying divergence order less obvious. This uncertainty could be the result of the divergence of the three subspecies close in time, or that introgression has been frequent since divergence. In particular, we found that pseudo-chromosome 2 in subsp. montivagans was much more diverged than other parts of the genomes. This could either be explained by specific capture of chromosome 2 from an unknown related species through hybridization or by conservation of chromosome 2 despite intermittent or ongoing introgression affecting more permeable parts of the genomes. A higher degree of chromosomal rearrangements on pseudo-chromosome 2 support the second hypothesis. Species tree analyses recovered an overall topology where subsp. montivagans diverged first and subsp. ruderalis and subsp. polymorpha appeared as sister lineages. Each subspecies was associated with its own chloroplast and mitochondrial haplotype group. Our data suggest introgression but refute a previous hypothesis that subsp. ruderalis is a new stabilized hybrid between the other two subspecies.
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| 7. |
- Linde, Anna-Malin, et al.
(författare)
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Genome Evolution in Plants: Complex Thalloid Liverworts (Marchantiopsida)
- 2023
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653. ; 15:3
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Tidskriftsartikel (refereegranskat)abstract
- Why do some genomes stay small and simple, while others become huge, and why are some genomes more stable? In contrast to angiosperms and gymnosperms, liverworts are characterized by small genomes with low variation in size and conserved chromosome numbers. We quantified genome evolution among five Marchantiophyta (liverworts), measuring gene characteristics, transposable element (TE) landscape, collinearity, and sex chromosome evolution that might explain the small size and limited variability of liverwort genomes. No genome duplications were identified among examined liverworts and levels of duplicated genes are low. Among the liverwort species, Lunularia cruciata stands out with a genome size almost twice that of the other liverwort species investigated here, and most of this increased size is due to bursts of Ty3/Gypsy retrotransposons. Intrachromosomal rearrangements between examined liverworts are abundant but occur at a slower rate compared with angiosperms. Most genes on L. cruciata scaffolds have their orthologs on homologous Marchantia polymorpha chromosomes, indicating a low degree of rearrangements between chromosomes. Still, translocation of a fragment of the female U chromosome to an autosome was predicted from our data, which might explain the uniquely small U chromosome in L. cruciata. Low levels of gene duplication, TE activity, and chromosomal rearrangements might contribute to the apparent slow rate of morphological evolution in liverworts.
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| 8. |
- Linde, Anna-Malin
(författare)
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Rates and patterns of bryophyte molecular evolution
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plants have been growing on land for at least 450 million years. The bryophytes comprising the three phyla liverworts, mosses and hornworts, are considered to be the closest extant relatives to the plants that colonized land. Bryophytes has been described as evolutionary “unchanging sphinxes of the past” regarding both morphological and genetic potential. This suggestion has some support in limited studies of molecular evolution within bryophytes, but has also been questioned based on e.g., studies of species diversification rates. To shed more light on this controversy, the overall aim of this thesis is to investigate rates and patterns of bryophyte molecular evolution.Our data suggest that the per nucleotide mutation rates in bryophytes are lower than those in angiosperms. Likewise, angiosperms are also more dynamic in terms of genome size, structural rearrangements, genome duplications and transposon activity. However, our data show that mutation rates of bryophytes are higher or at least on par with those of gymnosperms. Genome evolution in bryophytes is actually, in many aspects, similar to that of gymnosperms. Gymnosperms and bryophytes are both characterized by a low speciation rate, a low nucleotide mutation rate, low variation in chromosome numbers and relatively stable genome sizes. Studies have also suggested that macrosynteny is better conserved between conifer species compared with angiosperms, just as this study shows for bryophytes.Hybridization and introgression has been suggested to affect speciation and evolution. Recent genomic data shows that hybridization and introgression in angiosperms is more common then previously thought, but the question is less well studied in bryophytes. The present study gave some support to the occurrence of introgression between Marchantia polymorpha subspecies, but refute a previous hypothesis that M. polymorpha subsp. ruderalis is a new stabilized hybrid between M. polymorpha montivagans and polymorpha.An additional aspect of genome evolution and complexity is changes in gene regulatory networks. Gene regulatory networks generally appear more complex in angiosperms compared with bryophytes; also reflected in the circadian clock; with more gene components and more duplicated paralogous members, with possibly overlapping function, allowing a more robust and flexible system. Our studies of the plant circadian clock revealed that orthologs of most genes of the A. thaliana clock were present already in charophycean algae. Although gene numbers and complexity have generally increased during plant circadian clock evolution, our results suggest that gene loss has also been important in shaping the circadian clocks in the three bryophyte groups.
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| 9. |
- Linde, Anna-Malin, et al.
(författare)
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Rates and patterns of molecular evolution in bryophyte genomes, with focus on complex thalloid liverworts, Marchantiopsida
- 2021
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier. - 1055-7903 .- 1095-9513. ; 165
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Tidskriftsartikel (refereegranskat)abstract
- Plants commonly referred to as "bryophytes" belong to three major lineages of non-vascular plants: the liverworts, the hornworts and the mosses. They are unique among land plants in having a dominant haploid generation and a short-lived diploid sporophytic generation. The dynamics of selection acting on a haploid genome differs from those acting on a diploid genome: new mutations are directly exposed to selection. The general aim of this paper is to investigate the diversification rate of bryophytes - measured as silent site substitution rate representing neutral evolution (mutation rate) and the nonsynonymous to synonymous substitution rate ratio (dN/dS) representing selective evolution - and compare it with earlier studies on vascular plants. Results show that the silent site substitution rate is lower for liverworts as compared to angiosperms, but not as low as for gymnosperms. The selection pressure, measured as dN/dS, is not remarkably lower for bryophytes as compared to other diploid dominant plants as would be expected by the masking hypothesis, indicating that other factors are more important than ploidy.
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| 10. |
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