Encontrados 16 documentos, a visualizar página 1 de 2
Involvement of disperse repetitive sequences in wheat/rye genome adjustment
Tomás, Diana; Bento, Miguel; Viegas, Wanda; Silva, ManuelaThe union of different genomes in the same nucleus frequently results in hybrid genotypes with improved genome plasticity related to both genome remodeling events and changes in gene expression. Most modern cereal crops are polyploid species. Triticale, synthesized by the cross between wheat and rye, constitutes an excellent model to study polyploidization functional implications. We intend to attain a deeper k...
Genome merger: from sequence rearrangements in triticale to their elimination i...
Silva, Manuela; Viegas, Wanda; Bento, Miguel; Gustafson, PerryAbstract Genetic and epigenetic modifications resulting from different genomes adjusting to a common nuclear environment have been observed in polyploids. Sequence restructuring within genomes involving retrotransposon/ microsatellite-rich regions has been reported in triticale. The present study uses inter-retrotransposon amplified polymorphisms (IRAP) and retrotransposon microsatellite amplified polymorphisms...
Rye Bs disclose ancestral sequences in cereal genomes with a potential role in ...
Pereira, H. Sofia; Barão, Augusta; Caperta, A.; Rocha, João; Viegas, Wanda; Delgado, MargaridaResearch Article ; Two sequence families, E3900 and D1100, are amplified on the subtelomeric domain of the long arm of rye B chromosomes, the region that controls its drive mechanism. In this work, polymerase chain reaction (PCR) with a number of primers spanning E3900 shows that the organization and nucleotide sequence of E3900-related portions are present and highly conserved on rye A chromosomes as well as ...
Distribution patterns of phosphorylated Thr 3 and Thr 32 of histone H3 in plant...
Caperta, A.; Rosa, M.; Delgado, M.; Karimi, R.; Demidov, D.; Viegas, Wanda; Houben, A.Cell cycle dependent phosphorylation of conserved N-terminal tail residues of histone H3 has been described in both animal and plant cells. Through cytogenetic approaches using different plant species we show a detailed description of distribution patterns of phosphorylated histone H3 at either threonine 3 or threonine 32 in mitosis and meiosis. In meristematic cells of the large genome species Secale cereale, ...
Polyploidization as a retraction force in plant genome evolution: sequence rear...
Silva, Manuela; Viegas, Wanda; Bento, Miguel; Pereira, H. Sofia; Rocheta, Margarida; Gustafson, PerryBackground. Polyploidization is a major evolutionary process in plants where hybridization and chromosome doubling induce enormous genomic stress and can generate genetic and epigenetic modifications. However, proper evaluation of DNA sequence restructuring events and the precise characterization of sequences involved are still sparse. Methodology/Principal Findings. Inter Retrotransposons Amplified Polymorphis...
Interplay of ribosomal DNA Loci in nucleolar dominance: dominant NORs are up-re...
Silva, Manuela; Viegas, Wanda; Pereira, H. Sofia; Bento, Miguel; Santos, Ana Paula; Shaw, Peter; Delgado, Margarida; Neves, NunoBackground: Chromatin organizational and topological plasticity, and its functions in gene expression regulation, have been strongly revealed by the analysis of nucleolar dominance in hybrids and polyploids where one parental set of ribosomal RNA (rDNA) genes that are clustered in nucleolar organizing regions (NORs), is rendered silent by epigenetic pathways and heterochromatization. However, information on the...
Transcriptionally active heterochromatin in rye B chromosomes
Carchilan, Mariana; Delgado, Margarida; Ribeiro, Teresa; Nunes, Pedro Costa; Caperta, A.; Morais-Cecílio, L.; Jones, R. Neil; Viegas, WandaB chromosomes (Bs) are dispensable components of the genomes of numerous species. Thus far, there is a lack of evidence for any transcripts of Bs in plants, with the exception of some rDNA sequences. Here, we show that the Giemsa bandingpositive heterochromatic subterminal domain of rye (Secale cereale) Bs undergoes decondensation during interphase. Contrary to the heterochromatic regions of A chromosomes, this...
Relationships between transcription, silver staining and chromatin organization...
Caperta, A.; Neves, Nuno; Viegas, Wanda; Pikaard, Craig S.; Preuss, SashaSummary. The nucleolar organizer regions (NORs) are composed of hundreds of rRNA genes, typically spanning several megabases. Cytologically, NORs include regions that are highly condensed and regions that are decondensed, the latter corresponding to regions at which associated proteins stain intensively with silver (Ag-NORs) and where active rRNA gene transcription is thought to occur. To test the relationship ...
Postembryonic establishment of megabase-scale gene silencing in nucleolar domin...
Silva, Manuela; Viegas, Wanda; Pontes, Olga; Lawrence, Richard; Preuss, Sasha; Costa-Nunes, Pedro; Earley, Keith; Neves, Nuno; Pikaard, CraigNucleolar dominance is an epigenetic phenomenon in plant and animal genetic hybrids that describes the expression of 45S ribosomal RNA genes (rRNA genes) inherited from only one progenitor due to the silencing of the other progenitor’s rRNA genes. rRNA genes are tandemly arrayed at nucleolus organizer regions (NORs) that span millions of basepairs, thus gene silencing in nucleolar dominance occurs on a scale se...
Epigenetics: the functional memory of ribosomal genes
Viegas, Wanda; Silva, Manuela; Neves, NunoThe functional importance of Epigenetics arise from DNA sequencing programs that show the need for another code to explain the dynamics of gene expression patterns observed along cell differentiation and organism development. In this context, the study of ribosomal gene silencing is in fact an excellent model to better understand the relationships that are established between gene transcription and chromatin to...
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