| 1. |
- Andreou, Dimitrios, et al.
(författare)
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d-amino acid oxidase activator gene (DAOA) variation affects cerebrospinal fluid homovanillic acid concentrations in healthy Caucasians
- 2012
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Ingår i: European Archives of Psychiatry and Clinical Neuroscience. - : Springer Science and Business Media LLC. - 0940-1334 .- 1433-8491. ; 262:7, s. 549-556
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Tidskriftsartikel (refereegranskat)abstract
- The d-amino acid oxidase activator (DAOA) protein regulates the function of d-amino oxidase (DAO), an enzyme that catalyzes the oxidative deamination of d-3,4-dihydroxyphenylalanine (D-DOPA) and d-serine. D-DOPA is converted to l-3,4-DOPA, a precursor of dopamine, whereas d-serine participates in glutamatergic transmission. We hypothesized that DAOA polymorphisms are associated with dopamine, serotonin and noradrenaline turnover in the human brain. Four single-nucleotide polymorphisms, previously reported to be associated with schizophrenia, were genotyped. Cerebrospinal fluid (CSF) samples were drawn by lumbar puncture, and the concentrations of the major dopamine metabolite homovanillic acid (HVA), the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and the major noradrenaline metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) were measured. Two of the investigated polymorphisms, rs3918342 and rs1421292, were significantly associated with CSF HVA concentrations. Rs3918342 was found to be nominally associated with CSF 5-HIAA concentrations. None of the polymorphisms were significantly associated with MHPG concentrations. Our results indicate that DAOA gene variation affects dopamine turnover in healthy individuals, suggesting that disturbed dopamine turnover is a possible mechanism behind the observed associations between genetic variation in DAOA and behavioral phenotypes in humans.
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| 2. |
- Andreou, Dimitrios, et al.
(författare)
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Dystrobrevin-binding protein 1 gene (DTNBP1) variants associated with cerebrospinal fluid homovanillic acid and 5-hydroxyindoleacetic acid concentrations in healthy volunteers
- 2011
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Ingår i: European Neuropsychopharmacology. - : Elsevier BV. - 0924-977X .- 1873-7862. ; 21:9, s. 700-704
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Tidskriftsartikel (refereegranskat)abstract
- The dystrobrevin binding protein-1 (DTNBP1) gene encodes dysbindin-1, a protein involved in neurodevelopmental and neurochemical processes related mainly to the monoamine dopamine. We investigated possible associations between eleven DTNBP1 polymorphisms and cerebrospinal fluid (CSF) concentrations of the major dopamine metabolite homovanillic acid (HVA), the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), and the major noradrenaline metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) in healthy human subjects (n=132). Two polymorphisms, rs2619538 and rs760666, were nominally associated with CSF HVA and 5-HIAA concentrations, whereas a third polymorphism, rs909706, showed association only with HVA. After correction for multiple testing only the associations between rs2619538 and HVA and 5-HIAA concentrations remained significant. No significant association was found between any of the investigated DTNBP1 polymorphisms and CSF MHPG concentrations. The results suggest that genetic variation in DTNBP1 gene affects the regulation of dopamine and serotonin turnover in the central nervous system of healthy volunteers.
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| 3. |
- Andreou, Dimitrios, et al.
(författare)
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Tryptophan hydroxylase gene 1 (TPH1) variants associated with cerebrospinal fluid 5-hydroxyindole acetic acid and homovanillic acid concentrations in healthy volunteers
- 2010
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Ingår i: Psychiatry Research. - : Elsevier BV. - 0165-1781 .- 1872-7123. ; 180:2-3, s. 63-67
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Tidskriftsartikel (refereegranskat)abstract
- Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in serotonin synthesis. We investigated possible relationships between five TPH1 gene polymorphisms and cerebrospinal fluid (CSF) concentrations of the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), the major dopamine metabolite homovanillic acid (HVA), and the major norepinephrine metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) in healthy volunteers (n = 132). The G-allele of the TPH1 rs4537731 (A-6526G) polymorphism was associated with 5-HIM and HVA, but not MHPG concentrations. None of the other four TPH1 polymorphisms (rs211105, rs1800532, rs1799913 and rs7933505) were significantly associated with any of the monoamine metabolite concentrations. Two (rs4537731G/rs211105T/rs1800532C/rs1799913C/rs7933505G and rs4537731A/rs211105T/rs1800532C/rs1799913C/rs7933505G) of five common TPH1 five-allele haplotypes were associated with 5-HIAA and HVA concentrations in opposite directions. None of the common haplotypes was associated with MHPG concentrations in the CSF. The results suggest that TPH1 gene variation participates in the regulation of serotonin and dopamine turnover rates in the central nervous system of healthy human subjects.
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| 4. |
- Backström, Niclas, et al.
(författare)
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A high-density scan of the Z chromosome in ficedula flycatchers reveals candidate loci for diversifying selection
- 2010
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 64:12, s. 3461-3475
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical and empirical data suggest that genes located on sex chromosomes may play an important role both for sexually selected traits and for traits involved in the build-up of hybrid incompatibilities. We investigated patterns of genetic variation in 73 genes located on the Z chromosomes of two species of the flycatcher genus Ficedula, the pied flycatcher and the collared flycatcher. Sequence data were evaluated for signs of selection potentially related to genomic differentiation in these young sister species, which hybridize despite reduced fitness of hybrids. Seven loci were significantly more divergent between the two species than expected under neutrality and they also displayed reduced nucleotide diversity, consistent with having been influenced by directional selection. Two of the detected candidate regions contain genes that are associated with plumage coloration in birds. Plumage characteristics play an important role in species recognition in these flycatchers suggesting that the detected genes may have been involved in the evolution of sexual isolation between the species.
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| 5. |
- Backström, Niclas, et al.
(författare)
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Inferring the demographic history of European Ficedula flycatcher populations
- 2013
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 13, s. 2-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Inference of population and species histories and population stratification using genetic data is important for discriminating between different speciation scenarios and for correct interpretation of genome scans for signs of adaptive evolution and trait association. Here we use data from 24 intronic loci re-sequenced in population samples of two closely related species, the pied flycatcher and the collared flycatcher. Results: We applied Isolation-Migration models, assignment analyses and estimated the genetic differentiation and diversity between species and between populations within species. The data indicate a divergence time between the species of <1 million years, significantly shorter than previous estimates using mtDNA, point to a scenario with unidirectional gene-flow from the pied flycatcher into the collared flycatcher and imply that barriers to hybridisation are still permeable in a recently established hybrid zone. Furthermore, we detect significant population stratification, predominantly between the Spanish population and other pied flycatcher populations. Conclusions: Our results provide further evidence for a divergence process where different genomic regions may be at different stages of speciation. We also conclude that forthcoming analyses of genotype-phenotype relations in these ecological model species should be designed to take population stratification into account.
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| 6. |
- Cramer, Emily R. A., et al.
(författare)
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Testing a post-copulatory pre-zygotic reproductive barrier in a passerine species pair
- 2014
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 1432-0762 .- 0340-5443. ; 68:7, s. 1133-1144
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Tidskriftsartikel (refereegranskat)abstract
- Sexual selection may drive speciation, but most research focuses on pre-copulatory sexual selection, overlooking post-copulatory processes. Post-copulatory sexual selection in allopatric populations could drive divergence in post-copulatory pre-zygotic (PCPZ) phenotypes, limiting gene flow upon secondary contact. Here, we performed in vitro experiments examining one potential PCPZ barrier between two closely related passerine species, house sparrows (Passer domesticus) and Spanish sparrows (Passer hispaniolensis). In birds, crossing in the vagina may be particularly challenging for sperm, so we tested the effect of female reproductive tract fluids on sperm swimming speed and motility. If a PCPZ barrier exists at this stage of the fertilization process, heterospecific female fluids are predicted to reduce sperm swimming speed or motility relative to conspecific female fluid. We found that house sparrow female fluids affected the two species' sperm asymmetrically, depending on the control sperm velocity and male species. Overall, however, sperm performed equally in conspecific and heterospecific female fluids, and the species had similar sperm morphology and sperm swimming performance. Low divergence in PCPZ phenotypes between species, perhaps because post-copulatory sexual selection is stabilizing or only moderately strong in these taxa, may be insufficient to cause an overall PCPZ barrier. Reinforcement may be unlikely to drive PCPZ barriers for this species pair, because relatively effective pre-copulatory barriers exist between the species, and because hybrids can be quite successful. Testing the role of PCPZ barriers in birds with more divergent PCPZ phenotypes will improve our understanding of speciation in passerines.
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| 7. |
- Haukvik, Unn Kristin, et al.
(författare)
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An exploratory model for G x E interaction on hippocampal volume in schizophrenia; obstetric complications and hypoxia-related genes
- 2010
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Ingår i: Progress in Neuro-Psychopharmacology and Biological Psychiatry. - : Elsevier BV. - 0278-5846 .- 1878-4216. ; 34:7, s. 1259-1265
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Forskningsöversikt (refereegranskat)abstract
- Background Smaller hippocampal volume has repeatedly been reported in schizophrenia patients Obstetric complications (OCs) and single nucleotide polymorphism (SNP) variation in schizophrenia susceptibility genes have independently been related to hippocampal volume We investigated putative independent and interaction effects of severe hypoxia-related OCs and variation in four hypoxia-regulated schizophrenia susceptibility genes (BDNF, DTNBP1, GRM3 and NRG1) on hippocampal volume in schizophrenia patients and healthy controls. Methods Clinical assessment, structural MRI scans, and blood samples for genotyping of 32 SNPs were obtained from 54 schizophrenia patients and 53 control subjects Information on obstetric complications was collected from original birth records Results Severe OCs were related to hippocampal volume in both patients with schizophrenia and healthy control subjects Of the 32 SNPs studied, effects of severe OCs on hippocampal volume were associated with allele variation in GRM3 rs13242038, but the interaction effect was not specific for schizophrenia. SNP variation in any of the four investigated genes alone did not significantly affect hippocampal volume. Conclusions. The findings suggest a gene-environment (G x E) interaction between GRM3 gene variants and severe obstetric complications on hippocampus volume, independent of a diagnosis of schizophrenia Due to the modest sample size, the results must be considered preliminary and require replication in independent samples. (C) 2010 Elsevier Inc All rights reserved
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| 8. |
- Hedberg, Petter, et al.
(författare)
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A functional trait approach to fen restoration analysis
- 2013
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Ingår i: Applied Vegetation Science. - : Wiley. - 1402-2001 .- 1654-109X. ; 16:4, s. 658-666
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Tidskriftsartikel (refereegranskat)abstract
- Questions: Ecological restoration has traditionally been evaluated with analyses focused on species identities and abundances. These analyses provide no ecological explanation to why certain species change in abundance. One solution may be a functional trait analysis. We asked whether shifts in functional traits could explain vegetation changes in fens restored through tree cutting and rewetting, and how the functional traits in the restored sites compare to those of the reference site? Location: Three former rich fens in east-central Sweden. Methods: Tree cutting and rewetting were applied in a factorial design, and species and abundance data were recorded for 8yrs. Abundance data and trait data of canopy height, specific leaf area (SLA) and diaspore mass were used to calculate functional richness (FRic), functional divergence (FDiv), functional dispersion (FDis) and community-weighted mean (CWM) of functional traits. Data were analysed in a linear mixed effect model for vascular plants and bryophytes jointly, and for vascular plants separately. Results of restoration treatments were compared to data from a reference site. Results: Among vascular plants, tree cutting caused a decrease in SLA, as shade-sensitive species increased. In accordance with the change in SLA, FDis increased. In the joint analysis, tree cutting led to increased FDis, FDiv and FRic, indicating reduced filtering caused by the removal of the shading canopy, which allowed shade-sensitive species to establish. The comparison to the reference site shows that even after 8yrs, the restoration treatments have higher trait diversity than the reference site, indicating that the restoration sites have a too relaxed trait filter compared to conditions in an undisturbed fen. Our interpretation is that this is primarily caused by insufficient rewetting (and increased nutrient availability) that allow species of both natural and degraded fen conditions to co-exist, and which failed to suppress the regrowth of trees. Conclusions: Analysis of functional diversity improves our understanding of the ecological mechanisms affecting restoration results, and allows comparison among regions and communities with different species composition.
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| 9. |
- Hedberg, Petter, et al.
(författare)
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Vegetation recovery after multiple-site experimental fen restorations
- 2012
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 147:1, s. 60-67
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Tidskriftsartikel (refereegranskat)abstract
- Large peatland areas have been drained for forestry and agricultural purposes, resulting in the decline of characteristic biodiversity. Two measures commonly suggested for restoring drained fens is ditch blocking and tree removal to raise the groundwater table and increase light availability, respectively. In 2002, we initiated factorial restoration experiments, including ditch blocking and tree removal, in three former rich fens that had been drained for forestry purposes. Species cover of vascular plants and bryophytes were monitored during 8 years in permanent plots along transects perpendicular to the ditch for all four treatment combinations. Both methods had positive and independent effects on the cover of wetland vegetation. Specifically, Sphagnum species and wetland bryophytes showed a persistent positive response to both clear cutting and rewetting. Wetland vascular plants and grasses showed a persistent positive response to clear cutting. Sedges and species number responded positively to both clear cutting and ditch blocking, but the response was partly transient, and for species richness the response was limited when restoration methods were applied separately. Rich fen indicators of vascular plants and bryophytes did not respond to any of the restoration treatments. This indicates that species introduction in combination with further habitat restorations may be necessary to re-establish the original rich fen flora. Nevertheless, we conclude that the combination of ditch blocking and clear cutting are effective measures to partly restore wetland vegetation on previously drained and forested fens, while peat subsidence along the ditch may restrict the success further away from ditches.
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| 10. |
- Hermansen, Jo S., et al.
(författare)
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Hybrid speciation through sorting of parental incompatibilities in Italian sparrows
- 2014
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083. ; 23, s. 5831-5842
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Tidskriftsartikel (refereegranskat)abstract
- Speciation by hybridization is emerging as a significant contributor to biological diversification. Yet, little is known about the relative contributions of (i) evolutionary novelty and (ii) sorting of pre-existing parental incompatibilities to the build-up of reproductive isolation under this mode of speciation. Few studies have addressed empirically whether hybrid animal taxa are intrinsically isolated from their parents, and no study has so far investigated by which of the two aforementioned routes intrinsic barriers evolve. Here, we show that sorting of pre-existing parental incompatibilities contributes to intrinsic isolation of a hybrid animal taxon. Using a genomic cline framework, we demonstrate that the sex-linked and mitonuclear incompatibilities isolating the homoploid hybrid Italian sparrow at its two geographically separated hybrid–parent boundaries represent a subset of those contributing to reproductive isolation between its parent species, house and Spanish sparrows. Should such a sorting mechanism prove to be pervasive, the circumstances promoting homoploid hybrid speciation may be broader than currently thought, and indeed, there may be many cryptic hybrid taxa separated from their parent species by sorted, inherited incompatibilities.
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