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Please use this identifier to cite or link to this item: http://hdl.handle.net/10400.5/2402

Title: Nucleolar dominance: A 'David and Goliath' chromatin imprint process
Authors: Viegas, Wanda
Silva, Manuela
Neves, N.
Keywords: chromatin imprinting
nucleus
genome
hybrid
nucleolar dominance
Issue Date: 2002
Publisher: Bentham Science Publishers, Ltd
Citation: "Current Genomics". ISSN 1389-2029. 3 (2002) 563-576
Abstract: Nucleolar dominance is an enigma. The puzzle of differential amphiplasty has remained unresolved since it was first recognised and described in Crepis hybrids by Navashin in 1934. Here we review the body of knowledge that has grown out of the many models that have tried to find the genetic basis for differential rRNA gene expression in hybrids, and present a new interpretation. We propose and discuss a chromatin imprinting model which re-interprets differential amphiplasty in terms of two genomes of differing size occupying a common space within the nucleus, and with heterochromatin as a key player in the scenario. Difference in size between two parental genomes induces an inherited epigenetic mark in the hybrid that allows patterns of chromatin organization to have positional effects on the neighbouring domains. This chromatin imprinting model can be also used to explain complex genomic interactions which transcend nucleolar dominance and which can account for the overall characteristics of hybrids. Gene expression in hybrids, relative to parentage, is seen as being based on the nuclear location of the sequences concerned within their genomic environment, and where the presence of particular repetitive DNA sequences are ‘sensed’, and render silent the adjacent information.
URI: http://hdl.handle.net/10400.5/2402
ISSN: 1389-2029
Appears in Collections:CBAA - Artigos de Revista

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