| 1. |
- Brunhoff, Cecilia
(författare)
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Evolutionary History of the Root Vole (Microtus oeconomus) as Revealed by Y Chromosome and Mitochondrial DNA sequences
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The root vole (Microtus oeconomus) is a rodent with Holarctic distribution. In fact, it is the only Microtus vole found in both Eurasia and North America. Phylogeographic analyses of the root vole from across its distribution range were performed using mitochondrial and Y chromosome DNA sequences. Mitochondrial cytochrome b gene data demonstrate that the root vole is divided into four geographically distinct and well supported mtDNA phylogroups. Concordance between phylogeographic patterns in the root vole and other species suggest similarities in these species' responses to large-scale climatic change. The result of Y chromosome sequence analyses in the root vole is congruent with mtDNA, but the low sequence variability of the Y chromosome result in a phylogeographic pattern with much lower resolution. Differences between the mtDNA and Y chromosome phylogeographic patterns cannot be explained by differences in mutation rate alone, but is also affected by different evolutionary conditions and processes such as sex-biased dispersal, differences in male and female effective population sizes and local selective sweeps. Both mtDNA and Y chromosome data lend support for a subdivision of Fennoscandian root voles into two phylogroups with a complex history involving at least two colonization routes and, perhaps, glacial survival in northern Norway. These results contradict theoretical models that suggest low genetic diversity in previously glaciated areas. Analyses of two genetic markers, mtDNA and Y chromosome sequences, in concert have provided a more detailed picture of the evolutionary history of the root vole as well as the evolution of the two genetic systems. In addition, a phylogenetic study of 25 Microtus species based on mtDNA shows that the root vole belongs to an Asian group of Microtus voles.
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| 2. |
- Brunhoff, Cecilia, et al.
(författare)
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Glacial survival or late glacial colonization? Phylogeography of the root vole (Microtus oeconomus) in north-west Norway
- 2006
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Ingår i: Journal of Biogeography. - : Wiley. - 1365-2699 .- 0305-0270. ; 33:12, s. 2136-2144
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Tidskriftsartikel (refereegranskat)abstract
- Aim It has been proposed that the root vole subspecies, Microtus oeconomus finmarchicus, survived the last glacial period on islands on the north-west coast of Norway. The Norwegian island of Andoya may have constituted the only site with permanent ice-free conditions. Geological surveys and fossil finds from Andoya demonstrate that survival throughout the last glacial maximum was probably possible for some plants and animals. In this study we aim to infer the recent evolutionary history of Norwegian root vole populations and to evaluate the glacial survival hypothesis. Methods DNA sequence variation in the mitochondrial cytochrome b gene was studied in 46 root voles from 19 localities. Location Northern Fennoscandia and north-west Russia with a focus on islands on the north-west coast of Norway. Results The phylogeographical analyses revealed two North European phylogroups labelled 'Andoya' and 'Fennoscandia'. The Andoya phylogroup contained root voles from the Norwegian islands of Andoya, Ringvassoya and Reinoya and two localities in north-west Russia. The Fennoscandian phylogroup encompassed root voles from the three Norwegian islands of Kvaloya, Hakoya and Arnoya and the remaining specimens from Norway, northern Sweden and Finland. Nucleotide diversity within the Andoya and Fennoscandian phylogroups was similar, ranging from 0.5% to 0.7%. Main conclusions Both our genetic data and previously published morphological data are consistent with in situ glacial survival of root voles on Andoya during the last glacial maximum. However, the level of genetic diversity observed in the extant island populations, the past periods of severe climatic conditions on Andoya and the ecology of the root vole are somewhat difficult to reconcile with this model. A biogeographical scenario involving late glacial recolonization along the northern coasts of Russia and Norway therefore represents a viable alternative. Our results demonstrate that complex recolonization and extinction histories can generate intricate phylogeographical patterns and relatively high levels of genetic variation in northern populations.
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| 3. |
- Brunhoff, Cecilia, et al.
(författare)
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Holarctic phylogeography of the root vole (Microtus oeconomus): implications for late Quaternary biogeography of high latitudes
- 2003
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Ingår i: Molecular Ecology. - 0962-1083. ; 12:4, s. 957-968
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Tidskriftsartikel (refereegranskat)abstract
- A species-wide phylogeographical study of the root vole (Microtus oeconomus ) was performed using the whole 1140 base pair mitochondrial (mt) cytochrome b gene. We examined 83 specimens from 52 localities resulting in 65 unique haplotypes. Our results demonstrate that the root vole is divided into four main mtDNA phylogenetic lineages that seem to have largely allopatric distributions. Net divergence estimates (2.0-3.5%) between phylogroups, as well as relatively high nucleotide diversity estimates within phylogroups, indicate that the distinct phylogeographical structure was initiated by historical events that predated the latest glaciation. European root voles are divided into a Northern and a Central mtDNA phylogroup. The mtDNA data in concert with fossil records imply that root voles remained north of the classical refugial areas in southern Europe during the last glacial period. The currently fragmented populations in central Europe belong to a single mtDNA phylogroup. The Central Asian and the North European lineages are separated by the Ural Mountains, a phylogeographical split also found in collared lemmings (Dicrostonyx ) and the common vole (M. arvalis ). The Beringian lineage occurs from eastern Russia through Alaska to northwestern Canada. This distribution is congruent with the traditional boundaries of the Beringian refugium and with phylogeographical work on other organisms. In conclusion, similarities between the phylogeographical patterns in the root vole and other rodents, such as Arctic and subarctic lemmings, as well as more temperate vole species, indicate that late Quaternary geological and climatic events played a strong role in structuring northern biotic communities.
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| 4. |
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| 5. |
- Holm, Caroline, et al.
(författare)
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Cyclin A1 expression and associations with disease characteristics in childhood acute lymphoblastic leukemia
- 2006
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Ingår i: Leukemia Research. - : Elsevier. - 0145-2126 .- 1873-5835. ; 30:3, s. 254-261
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Tidskriftsartikel (refereegranskat)abstract
- A critical cell cycle regulatory protein, cyclin A1, has been implicated in the development of acute myeloid leukemia (AML). Here, we have examined the expression and clinical significance of cyclin A1 in childhood acute lymphoblastic leukemia (ALL). Cyclin A1 was highly expressed in lymphoblastic leukemic cell lines and in 22 of 30 ALL patients (73%). Cyclin A1 expression correlated with patient age (P=0.006), but not with cytogenetic abnormalities. Patients with high levels of cyclin A1 had poorer event-free survival (57.9%) compared to patients with lower levels (75%).
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| 6. |
- Jaarola, Maarit, et al.
(författare)
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Molecular phylogeny of the speciose vole genus Microtus (Arvicolinae, Rodentia) inferred from mitochondrial DNA sequences
- 2004
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1095-9513 .- 1055-7903. ; 33:3, s. 647-663
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Forskningsöversikt (refereegranskat)abstract
- Voles of the genus Microtus represent one of the most speciose mammalian genera in the Holarctic. We established a molecular phylogeny for Microtus to resolve contentious issues of systematic relationships and evolutionary history in this genus. A total of 81 specimens representing ten Microtus species endemic to Europe as well as eight Eurasian, six Asian and one Holarctic species were sequenced for the entire cytochrome b gene (1140 bp). A further 25 sequences were retrieved from GenBank, providing data on an additional 23, mainly Nearctic, Microtus species. Phylogenetic analysis of these 48 species generated four well-supported monophyletic lineages. The genus Chionomys, snow voles, formed a distinct and well-supported lineage separate from the genus Microtus. The subgenus Microtus formed the strongest supported lineage with two sublineage displaying a close relationship between the arvalis species group (common voles) and the socialis species group (social voles). Monophyly of the Palearctic pitymyid voles, subgenus Terricola, was supported, and this subgenus was also subdivided into two monophyletic species groups. Together, these groupings clarify long-standing taxonomic uncertainties in Microtus. In addition, the "Asian" and the Nearctic lineages reported previously were identified although the latter group was not supported. However, relationships among the main Microtus branches were not resolved. suggesting a rapid and potentially Simultaneous radiation of a widespread ancestor early in the history of the genus. This and subsequent radiations discernible in the cytochrome b phylogeny, show the considerable potential of Microtus for analysis of historical and ecological determinants of speciation in small mammals. It is evident that speciation is an ongoing process in the genus and that the molecular data provides a vital insight into current species limits as well as cladogenic events of the past. (C) 2004 Elsevier Inc. All rights reserved.
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| 7. |
- Wegiel, Barbara, et al.
(författare)
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A role for cyclin A1 in mediating the autocrine expression of vascular endothelial growth factor in prostate cancer
- 2005
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Ingår i: Oncogene. - : Nature Publishing Group. - 0950-9232 .- 1476-5594. ; 24:42, s. 6385-6393
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Tidskriftsartikel (refereegranskat)abstract
- Elevated levels of cyclin A1 expression have been implicated in acute myeloid leukemia and in male germ cell tumors. However, a role of cyclin A1 in tumorigenesis of prostate cancer has not been reported. In the present study, expression of cyclin A1 in patients with prostate cancer and a role of cyclin A1 in mediating expression of vascular endothelial growth factor (VEGF) were investigated. Cyclin A1 was highly expressed in aggressive tumors and was significantly correlated with VEGF expression in 96 patients with prostate cancer. Treatment of LNCaP cells with R1881, a synthetic androgen resulted in increased cyclin A1 expression. Induction of cyclin A1 expression in LNCaP cells led to an increase in VEGF expression and this effect was manifested upon the R1881 treatment. Cyclin A1 failed to mediate VEGF activation in DU-145 cells lacking a functional Rb and an androgen receptor (AR). Although AR expression was induced into DU-145 cells, cyclin A1 was unable to mediate VEGF expression. However, induced coexpression of cyclin A1, Rb and AR in DU-145 cells in the presence of R1881 greatly promoted VEGF promoter activity. This suggests that cyclin A1 mediates VEGF expression in cooperation with Rb- and androgen-dependent pathways in prostate cancer.
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