Encontrados 11 documentos, a visualizar página 1 de 2
Retrotransposons represent the most labile fraction for genomic rearrangements ...
Bento, M.; Tomás, D.; Viegas, W.; Silva, M.Understanding how increased genome size and diversity within polyploid genomes impacts plant evolution and breeding continues to be challenging. Although historical studies by McClintock suggested the importance of transposable elements mediated by polyploidisation on genomic changes, data from plant crosses remain scarce. Despite the absence of a conclusive proof regarding autonomous retrotransposon movement i...
Differential effects of high-temperature stress on nuclear topology and transcr...
Tomás, D.; Brazão, J.; Viegas, W.; Silva, M.The plant stress response has been extensively characterized at the biochemical and physiological levels. However, knowledge concerning repetitive sequence genome fraction modulation during extreme temperature conditions is scarce. We studied high-temperature effects on subtelomeric repetitive sequences (pSc200) and 45S rDNA in rye seedlings submitted to 40 ° C during 4 h. Chromatin organization patterns were e...
Size matters in Triticeae polyploids: larger genomes have higher remodeling
Bento, Miguel; Gustafson, J.P.; Viegas, W.; Silva, ManuelaReview ; Polyploidization is one of the major driving forces in plant evolution and is extremely relevant to speciation and diversity creation. Polyploidization leads to a myriad of genetic and epigenetic alterations that ultimately generate plants and species with increased genome plasticity. Polyploids are the result of the fusion of two or more genomes into the same nucleus and can be classified as allopoly...
Cochicine-induced polyploidization depends on tubulin polymerization in c-metap...
Caperta, A.; Delgado, M.; Ressurreição, F.; Meister, A.; Jones, R.N.; Viegas, W.; Houben, A.The microtubule cytoskeleton plays a crucial role in the cell cycle and in mitosis. Colchicine is a microtubule-depolymerizing agent that has long been used to induce chromosome individualization in cells arrested at metaphase and also in the induction of polyploid plants. Although attempts have been made to explain the processes and mechanisms underlying polyploidy induction, the role of the cytoskeleton still...
Ribosomal DNA heterochromatin in plants
Neves, N.; Delgado, M.; Silva, M.; Caperta, A.; Morais-Cecílio, L.; Viegas, W.The aim of this review is to integrate earlier results and recent findings to present the current state-of-the art vision concerning the dynamic behavior of the ribosomal DNA (rDNA) fraction in plants. The global organization and behavioral features of rDNA make it a most useful system to analyse the relationship between chromatin topology and gene expression patterns. Correlations between several heterochromat...
Different numbers of rye B chromosomes induce identical compaction changes in d...
Delgado, M.; Caperta, A.; Ribeiro, T.; Viegas, W.; Jones, R.N.; Morais-Cecilio, L.In rye each B chromosome (B) represents 5.5% of the diploid A genome. Rye Bs have several nuclear to whole plant effects although they seem to bear no genes except for the ones that lead to their maintenance within a population. In this context, and considering that rye Bs are enriched in repetitive non-coding regions that build up heterochromatin (het), we investigated the influence of Bs on the organization o...
Nucleolar dominance in triticales: control by unlinked genes
Neves, N.; Silva, M.; Heslop-Harrison, J.S.; Viegas, W.Hybrid plants and animals often show suppression of activity of ribosomal genes (rDNA) originating from one of the parental or ancestral species. In the wheat6rye amphiploid triticale, containing 28 chromosomes of wheat origin and 14 from rye, rDNA of rye origin (on chromosome 1R) is not normally expressed, while the 1B- and 6B-origin rDNA from wheat shows strong expression. Expression of rDNA can be accurately...
rRNA gene activity and control of expression mediated by methylation and imprin...
Neves, N.; Heslop-Harrison, J.S.; Viegas, W.Ribosomal RNA genes originating from one parent are often suppressed in interspecific hybrids. We show that treatments during germination with the cytosine analogue 5-azacytidine stably reactivate the expression of the suppressed rRNA genes of rye origin in the wheat x rye amphiploid, triticale, by preventing methylation of sites in the rye rDNA. When 5-azacytidine is applied to embryos of triticale and wheat x...
The developmental stage of inactivation of rye origin rRNA genes in the embryo ...
Castilho, A.; Queiroz, A.; Neves, N.; Barão, A.; Silva, M.; Viegas, W.To identify the developmental stage during which the preferential inactivation of rRNA genes from the rye parent occurs in wheat x rye hybrids, nucleolar activity was evaluated in the embryo and endosperm of developing seeds of the hybrids. The hybrids were obtained from crosses of euploid and aneuploid lines of hexaploid wheat, Triticum aestivum cv. Chinese Spring, with rye, Secale cereale cv. Centeio do Alto....
Reprogramming of rye rDNA in triticale during microsporogenesis
Silva, M.; Queiroz, A.; Neves, N.; Barão, A.; Castilho, A.; Morais-Cecilio, L.; Viegas, W.To test the hypothesis that interspecific genomic and chromosome interactions leading to nucleolar dominance could be reprogrammed in meiosis, we compared the expression of distinct nucleolar organizing region (NOR) loci in hexaploid triticale root tip meristematic cells, pollen mother cells and young pollen grains. Interphase and metaphase cells were silver stained to quantify nucleoli and active NOR loci resp...
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