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Different numbers of rye B chromosomes induce identical compaction changes in distinct A chromosome domains
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Orientador(es)
Resumo(s)
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 of two
chromatin fractions, namely the ribosomal DNA (facultative
het) and satellite (non-het) domain of rye chromosome 1 by
silver staining on root tip metaphase cells. The results show that
rye Bs cause condensation both in the NOR and in the chromosome
1 satellite domain. Since the silver staining technique used is indicative of the transcriptional activity of the NORs,
the condensation observed at those loci demonstrates that the
rRNA gene arrays are down-regulated in the presence of Bs,
regardless of their number per individual. Furthermore, the
organizational changes of metaphase NORs find parallel with
the interphase organization of ribosomal chromatin, since the
frequency of cells with intranucleolar condensed rDNA regions
increases drastically and nuclear matrix attachment pattern is
altered in the presence of the Bs. Our results show an identical
effect of the Bs on the organization of two distinct chromosome
domains displaying a presence/absence dichotomy
Descrição
Palavras-chave
B chromosomes DNA rye
Contexto Educativo
Citação
"Cytogenetic and Genome Research". ISSN 1424-8581. 106 (2004) 320-324