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ABSTRACT: BACKGROUND: Monopartite begomoviruses (genus Begomovirus, family Geminiviridae) that infect sweet potato (Ipomoea batatas) around the world are known as sweepoviruses. Because sweet potato plants are vegetatively propagated, the accumulation of viruses can become a major constraint for root production. Mixed infections of sweepovirus species and strains can lead to recombination, which may contribute to the generation of new recombinant sweepoviruses. RESULTS: This study reports the full genome sequence of 34 sweepoviruses sampled from a sweet potato germplasm bank and commercial fields in Brazil. These sequences were compared with others from public nucleotide sequence databases to provide a comprehensive overview of the genetic diversity and patterns of genetic exchange in sweepoviruses isolated from Brazil, as well as to review the classification and nomenclature of sweepoviruses in accordance with the current guidelines proposed by the Geminiviridae Study Group of the International Committee on Taxonomy of Viruses (ICTV). Co-infections and extensive recombination events were identified in Brazilian sweepoviruses. Analysis of the recombination breakpoints detected within the sweepovirus dataset revealed that most recombination events occurred in the intergenic region (IR) and in the middle of the C1 open reading frame (ORF). CONCLUSIONS: The genetic diversity of sweepoviruses was considerably greater than previously described in Brazil. Moreover, recombination analysis revealed that a genomic exchange is responsible for the emergence of sweepovirus species and strains and provided valuable new information for understanding the diversity and evolution of sweepoviruses.
Virology Journal 10/2012; 9(1):241. · 2.34 Impact Factor
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ABSTRACT: As a result of surveys of okra begomoviruses (genus Begomovirus, family Geminiviridae) conducted over the last five years in Central Brazil, we report the complete genome sequence of an isolate of okra mottle virus (OMoV). The DNA-A and DNA-B components were 2660 and 2653 nucleotides (nt) long, respectively, and they were most closely related to the DNA-A (~99 % nt identity) and DNA-B (~98 % nt identity) components of an OMoV isolate from a soybean plant. A phylogenetic tree was generated based on these sequences, and it was shown that both of the OMoV DNA components were grouped in a branch with Brazilian begomoviruses known to infect weeds. By recombination analysis, strong evidence was observed that the OMoV genome may have been the product of a double inter-species recombination event.
Archives of Virology 09/2012; · 2.11 Impact Factor
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ABSTRACT: Tomato cultivation in Brazil is threatened by a number of tomato-infecting viruses belonging to the genus Begomovirus of the family Geminiviridae. Here, we report the full DNA-A sequences of three Brazilian begomoviruses: a potentially new tomato-infecting viruses, tomato interveinal chlorosis virus (ToICV), and two previously proposed begomoviruses for which only partial DNA-A sequences are available in the databases: tomato mottle leaf curl virus (TMoLCV) and tomato golden vein virus (TGVV). The complete sequences of the DNA-B components of TMoLCV and TGVV and the DNA-A components of a number of tomato severe rugose virus variants are also presented. Collectively, all of the analyzed sequences were phylogenetically clustered within the two major groups of Brazilian tomato-infecting begomoviruses.
Archives of Virology 01/2012; 157(4):747-52. · 2.11 Impact Factor
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ABSTRACT: Although adipocyte terminal differentiation has been extensively studied, the early steps of adipocyte development and the embryonic origin of this lineage remain largely unknown. Here we describe a novel role for the pre-B-cell leukemia transcription factor one (PBX1) in adipocyte development using both mouse embryonic stem cells (mESCs) and human multipotent adipose-derived stem (hMADS) cells. We show that Pbx1(-/-) mESCs are unable to generate adipocytes, despite normal expression of neuroectoderm and neural crest (NC) markers. Early adipocyte lineage markers are not induced in Pbx1(-/-) mESCs, suggesting that Pbx1 controls the generation and/or the maintenance of adipocyte progenitors (APs) from the NC. We further characterize the function of PBX1 in postnatal adipogenesis and show that silencing of PBX1 expression in hMADS cells reduces their proliferation by preventing their entry in the S phase of the cell cycle. Furthermore, it promotes differentiation of hMADS cells into adipocytes and partially substitutes for glucocorticoids and rosiglitazone, two key proadipogenic agents. These effects involve direct modulation of PPARγ activity, most likely through regulation of the biosynthesis of PPARγ natural endogenous ligand(s). Together, our data suggest that PBX1 regulates adipocyte development at multiple levels, promoting the generation of NC-derived APs during embryogenesis, while favoring APs proliferation and preventing their commitment to the adipocyte lineage in postnatal life.
Stem Cells 09/2011; 29(11):1837-48. · 7.78 Impact Factor
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Fernanda R Fernandes, Leonardo C Albuquerque,
Cristiane L de Oliveira,
Andréa R R Cruz,
Wesley B da Rocha,
Talita G Pereira,
Fernanda Y B Naito,
Natália de M Dias,
Tatsuya Nagata,
Josias C Faria,
Francisco M Zerbini,
Francisco J L Aragão,
Alice K Inoue-Nagata
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ABSTRACT: To date, no begomovirus has been fully characterized from Euphorbia heterophylla, a widely distributed weed, in Brazil. Here, we show the occurrence of a new begomovirus on E. heterophylla plants showing bright yellow mosaic. The bipartite viral genome was cloned from 10 samples, and all clones are almost identical to each other (95.6-98.8% nucleotide sequence identity). The DNA-A sequences shared a maximum nucleotide sequence identity of 87.3% with euphorbia mosaic Peru virus (EuMPV) and thus were classified as belonging to a novel begomovirus species, tentatively named Euphorbia yellow mosaic virus (EuYMV). The EuYMV DNA-B sequences share a maximum nucleotide sequence identity of 56.2% with a euphorbia mosaic virus (EuMV) isolate from Mexico. Phylogenetic analysis demonstrated that this new virus belongs to a different lineage than EuMV isolates from Central America.
Archives of Virology 07/2011; 156(11):2063-9. · 2.11 Impact Factor
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ABSTRACT: The complete genome sequences of two monopartite begomovirus isolates (genus Begomovirus, family Geminiviridae) present in a single sweet potato (Ipomoea batatas) plant collected in São Paulo, Brazil, are presented. Based on the current taxonomic criteria for the genus Begomovirus, one of the isolates was shown to represent a novel species, tentatively named Sweet potato leaf curl Sao Paulo virus (SPLCSPV). The other isolate represented a new strain of sweet potato leaf curl virus, named sweet potato leaf curl virus-Sao Paulo (SPLCV-SP). The full genome sequence of the SPLCSPV isolate shared the highest nucleotide identity (87.6%) with isolates of sweet potato leaf curl Spain virus (SPLCESV). Phylogenetic and recombination analyses were used to investigate the relationships of these isolates to other monopartite Ipomoea-infecting begomoviruses.
Archives of Virology 05/2011; 156(7):1291-4. · 2.11 Impact Factor
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Nathalie Billon,
Raivo Kolde,
Jüri Reimand, Miguel C Monteiro,
Meelis Kull,
Hedi Peterson,
Konstantin Tretyakov,
Priit Adler,
Brigitte Wdziekonski,
Jaak Vilo,
Christian Dani
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ABSTRACT: The current epidemic of obesity has caused a surge of interest in the study of adipose tissue formation. While major progress has been made in defining the molecular networks that control adipocyte terminal differentiation, the early steps of adipocyte development and the embryonic origin of this lineage remain largely unknown.
Here we performed genome-wide analysis of gene expression during adipogenesis of mouse embryonic stem cells (ESCs). We then pursued comprehensive bioinformatic analyses, including de novo functional annotation and curation of the generated data within the context of biological pathways, to uncover novel biological functions associated with the early steps of adipocyte development. By combining in-depth gene regulation studies and in silico analysis of transcription factor binding site enrichment, we also provide insights into the transcriptional networks that might govern these early steps.
This study supports several biological findings: firstly, adipocyte development in mouse ESCs is coupled to blood vessel morphogenesis and neural development, just as it is during mouse development. Secondly, the early steps of adipocyte formation involve major changes in signaling and transcriptional networks. A large proportion of the transcription factors that we uncovered in mouse ESCs are also expressed in the mouse embryonic mesenchyme and in adipose tissues, demonstrating the power of our approach to probe for genes associated with early developmental processes on a genome-wide scale. Finally, we reveal a plethora of novel candidate genes for adipocyte development and present a unique resource that can be further explored in functional assays.
Genome biology 01/2010; 11(8):R80. · 6.63 Impact Factor
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ABSTRACT: Key events leading to terminal differentiation of preadipocytes into adipocytes have been identified in recent years. However, signaling pathways involved in the decision of stem cells to follow the adipogenic lineage have not yet been characterized. We have previously shown that differentiating mouse embryonic stem (mES) cells give rise to functional adipocytes upon an early treatment with retinoic acid (RA). The goal of this work was to identify regulators of RA-induced commitment of mES cells to the adipocyte lineage. First, we investigated the role of RA receptor (RAR) isotypes in the induction of mES cell adipogenesis. Using synthetic retinoids selective of RAR isotypes, we show that RARbeta activation is both sufficient and necessary to trigger commitment of mES cells to adipocytes. Then, we performed a small-scale drug screening to find signaling pathways involved in RARbeta-induced mES cell adipogenesis. We show that pharmacological inhibitors of glycogen synthase kinase (GSK) 3, completely inhibit RARbeta-induced adipogenesis in mES cells. This finding uncovers the requirement of active GSK3 in RARbeta-induced commitment of mES cells toward the adipocyte lineage. Finally, we investigated the role of the Wnt pathway, in which GSK3 is a critical negative regulator, in adipocyte commitment by analyzing Wnt pathway activity in RA- and RARbeta-induced mES cell adipogenesis. Our results suggest that although RARbeta and active GSK3 are required for RA-induced adipogenesis, they might be acting through a Wnt pathway-independent mechanism.
Stem cells and development 09/2008; 18(3):457-63. · 4.15 Impact Factor
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ABSTRACT: The bacteriophage phiDNA polymerase amplifies circular DNA in a rolling circle amplification mechanism. This characteristic was applied to amplify and clone the complete circular DNA genome of a begomovirus. Total DNA extracted from infected tissue was used as the template of an amplification reaction using the commercial kit TempliPhi (Amersham Biosciences). The amplified DNA could be used for direct sequencing and was cloned after digestion with a single cutting restriction endonuclease. The use of this enzyme simplified the cloning steps and increased the cloning efficiency of the complete genome of a circular plant DNA virus.
Journal of Virological Methods 04/2004; 116(2):209-11. · 2.01 Impact Factor
