INVESTIGADORES
ACOSTA Maria Cristina
artículos
Título:
B Chromosomes in Nierembergia aristata (Solanaceae): Nucleolar Activity and Competition with the A Chromosomes
Autor/es:
ACOSTA M. C.; MOSCONE E. A.
Revista:
CYTOGENETIC AND GENOME RESEARCH
Editorial:
KARGER
Referencias:
Lugar: Basel; Año: 2011 vol. 132 p. 105 - 112
ISSN:
1424-8581
Resumen:
B chromosomes are additional dispensable chromosomes that may be present in some individuals, populations, or species, which have probably arisen from the A chromosomes but follow their own evolutionary pathway. Supposedly, B chromosomes do not contain major genes except for ribosomal DNA (rDNA) sequences that have been mapped on the supernumerary chromosomes of many plants and animals. This paper is a new report of B chromosome occurrence in plants. B chromosomes with nucleolar organizing regions (NORs) were found in a diploid sample of Nierembergia aristata D. Don (sub nom. N. stricta Miers) (2n = 2x = 16). This is an extreme case in which B chromosomes possess not only strong nucleolar activity, as revealed by conventional staining methods, AgNOR and fluorescence banding, and fluorescent in situ hybridization (FISH), but also show nucleolar competition with the A chromosomes. The observed phenomenon could be analogous to the nucleolar dominance or ‘differential amphiplasty’ phenomenon that occurs in interspecific hybrids.